Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Koji Sagiyama Last modified date:2021.05.11

Assistant Professor / Department of Clinical Radiology / Radiology / Kyushu University Hospital

1. Yuzo Yamasaki, Mayumi Yoshikawa, Koji Sagiyama, Takeshi Kamitani, Active Cardiac Sarcoidosis Imitating Cardiac Metastases., Radiology. Cardiothoracic imaging, 10.1148/ryct.2020200310, 2, 6, e200310, 2020.12.
2. Yuzo Yamasaki, Kohtaro Abe, Takeshi Kamitani, Koji Sagiyama, Tomoyuki Hida, Kazuya Hosokawa, Yuko Matsuura, Kazuhito Hioki, Michinobu Nagao, Hidetake Yabuuchi, Kousei Ishigami, Right Ventricular Extracellular Volume with Dual-Layer Spectral Detector CT: Value in Chronic Thromboembolic Pulmonary Hypertension., Radiology, 10.1148/radiol.2020203719, 298, 3, 589-596, 2021.03, Background Right ventricular (RV) extracellular volumes (ECVs), as a surrogate for histologic fibrosis, have not been sufficiently investigated. Purpose To evaluate and compare RV and left ventricular (LV) ECVs obtained with dual-layer spectral detector CT (DLCT) in chronic thromboembolic pulmonary hypertension (CTEPH) and investigate the clinical importance of RV ECV. Materials and Methods Retrospective analysis was performed on data from 31 patients with CTEPH (17 were not treated with pulmonary endarterectomy [PEA] or balloon pulmonary angioplasty [BPA] and 14 were) and eight control subjects who underwent myocardial delayed enhancement (MDE) DLCT from January 2019 to June 2020. The ECVs in the RV and LV walls were calculated by using iodine density as derived from spectral data pertaining to MDE. Statistical analyses were performed with one-way repeated analysis of variance with the Tukey post hoc test or the Kruskal-Wallis test with the Steel-Dwass test and linear regression analysis. Results The PEA- and BPA-naive group showed significantly higher ECVs than the PEA- or BPA-treated group and control group in the septum (28.2% ± 2.9 vs 24.3% ± 3.6, P = .005), anterior right ventricular insertion point (RVIP) (32.9% ± 4.6 vs 25.3% ± 3.6, P < .001), posterior RVIP (35.2% ± 5.2 vs 27.3% ± 4.2, P < .001), mean RVIP (34.0% ± 4.2 vs 26.3% ± 3.4, P < .001), RV free wall (29.5% ± 3.3 vs 25.9% ± 4.1, P = .036), and mean RV wall (29.1% ± 3.0 vs 26.1% ± 3.1, P = .029). There were no significant differences between the PEA- or BPA-treated group and control subjects in these segments (septum, P = .93; anterior RVIP, P = .38; posterior RVIP, P = .52; mean RVIP, P = .36; RV free wall, P = .97; and mean RV, P = .33). There were significant correlations between ECV and mean pulmonary artery pressure (PAP) or brain natriuretic peptide (BNP) in the mean RVIP (mean PAP: R = 0.66, P < .001; BNP: R = 0.44, P = .014) and the mean RV (mean PAP: R = 0.49, P = .005; BNP: R = 0.44, P = .013). Conclusion Right ventricular and right ventricular insertion point extracellular volumes could be noninvasive surrogate markers of disease severity and reverse tissue remodeling in chronic thromboembolic pulmonary hypertension. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Sandfort and Bluemke in this issue..
3. Yuzo Yamasaki, Takeshi Kamitani, Koji Sagiyama, Yuko Matsuura, Tomoyuki Hida, Hazumu Nagata, Model-based iterative reconstruction for 320-detector row CT angiography reduces radiation exposure in infants with complex congenital heart disease., Diagnostic and interventional radiology (Ankara, Turkey), 10.5152/dir.2020.19633, 27, 1, 42-49, 2021.01, PURPOSE: We investigated the impact of model-based iterative reconstruction (MBIR) on 320-detector row computed tomography angiography (CTA) in infants with complex congenital heart disease (CHD). METHODS: Seventy infants with complex CHD who underwent 320-detector row CTA (40 boys and 30 girls; age range, 0-22 months; median age, 60 days) were retrospectively evaluated. First, the images were reconstructed by filtered back projection (FBP), hybrid iterative reconstruction (HIR), or MBIR in 20 cases, and variables were compared among the three iterative reconstruction methods (IR test). Second, the variables were compared between 25 cases scanned using HIR and 25 cases scanned using MBIR, with a 20 standard deviation noise level for both. Attenuation values and contrast-to-noise ratios (CNRs) of the great vessels and heart chambers were calculated. Total dose-length products were recorded for all patients (radiation dose: RD test). RESULTS: In the IR test, the mean CNR values were 4.8±1.3 for FBP, 6.9±1.4 for HIR, and 8.2±1.7 for MBIR (P < 0.0001). The best subjective image qualities in the great vessels and heart chambers were obtained with MBIR. In RD testing, no significant differences between HIR and MBIR in image quality (CNR: HIR, 8.4±2.4; MBIR, 8.3±2.4) were observed. The effective dose was significantly lower for MBIR than for HIR (0.7±0.2 vs. 1.1±0.3 mSv; P < 0.001). CONCLUSION: The MBIR algorithm significantly improved image quality and decreased radiation exposure in 320-row CTA of infants with complex CHD, providing an alternative to FBP or HIR that is both safer and produces better results..
4. Ken Sakaie, Masaya Takahashi, Koji Sagiyama, Ivan Dimitrov, Teresa Frohman, Gina Remington, Elliot Frohman, Robert J. Fox, INJURY TO A SPECIFIC NEURAL PATHWAY DETECTED BY ULTRA-HIGH-FIELD MRI, NEUROLOGY, 10.1212/WNL.0000000000000016, 82, 2, 182-183, 2014.01, We present evidence for the potential of ultra-high-field MRI to reveal injury due to multiple sclerosis (MS) not appreciated using lower field imaging. Internuclear ophthalmoplegia (INO) is an eloquent ocular motor syndrome that frequently affects patients with MS. The medial longitudinal fasciculus (MLF) is a periventricular, dorsomedial brainstem tegmentum pathway that yokes the 2 eyes in many types of eye movements.(1,2) Further, T2 lesions localized in the region containing the MLF strongly associate with INO.(3) However, the small diameter of the MLF and lack of contrast between the MLF and the surrounding neural tissue on conventional MRI hinder direct visualization.(4) We recently demonstrated that the MLF is clearly visible on T2*-weighted images at 7T among healthy controls.(4) In this contribution, we demonstrate that hallmarks of the MLF are at most weakly evident among patients with MS with chronic INO. Three patients with MS with bilateral chronic INO (as shown in the figure, D-F: aged 43/52/32 years, male/female/female, primary progressive/relapsing-remitting/relapsing-remitting, Expanded Disability Status Scale score 6.0/5.0/6.0) and 3 healthy controls participated in an institutional review board-approved study. Images were acquired on a 7T Philips Achieva (Philips Healthcare, Cleveland, OH). As T2-weighted (as opposed to T2*-weighted) contrast on 7T images was not optimal for lesion detection, images were also acquired on a 3T system to assess conventional T2 lesions. Imaging at 7T included a multiecho fast field echo scan with high spatial resolution and T2* weighting (0.13 x 0.13 x 3 mm voxels, echo time = 12, 16, 20, 24 ms), with scan planes lying perpendicular to the brainstem. Subsequent coregistration with FSL5 put all images in a common space. The MLF is clearly visible on all healthy controls at all echo times over a range of as much as 15 mm in the inferior-superior direction (figure, A-C) but considerably less conspicuous or not visible in any of the patients with MS with INO (figure, D-F). Conventional T2-weighted imaging at 3T indicates, in each patient, bilateral lesions in the pons overlapping with locations expected for the MLF and (figure, G-I) extensive and typical T2 cerebral lesions of MS. Differences in contrast between the MLF and surrounding neural tissue may arise from microscopic changes to myelin structure, readily observed at ultra-high fields, which are inaccessible to technology commonly used in clinical centers. Myelin sheaths result in enhanced contrast in T2*-weighted images.(6) The lack of contrast in our MS cohort with INO likely arises from the reduction in myelin content and axons secondary to MS inflammatory injury..
5. Kazufumi Kikuchi, Osamu Togao, Koji Yamashita, Daichi Momosaka, Tomohiro Nakayama, Yoshiyuki Kitamura, Yoshitomo Kikuchi, Shingo Baba, Koji Sagiyama, Keisuke Ishimatsu, Ryotaro Kamei, Nobutaka Mukae, Koji Iihara, Satoshi O Suzuki, Toru Iwaki, Akio Hiwatashi, Diagnostic accuracy for the epileptogenic zone detection in focal epilepsy could be higher in FDG-PET/MRI than in FDG-PET/CT., European radiology, 10.1007/s00330-020-07389-1, 31, 5, 2915-2922, 2021.05, OBJECTIVES: To examine the utility of FDG-PET/MRI in patients with epilepsy by comparing the diagnostic accuracy of PET/MRI and PET/CT in epileptogenic zone (EZ) detection. METHODS: This prospective study included 31 patients (17 males, 14 females) who underwent surgical resection for EZ. All patients were first scanned using FDG-PET/CT followed immediately with FDG-PET/MRI. Two series of PET plus standalone MR images were interpreted independently by five board-certified radiologists. A 4-point visual score was used to assess image quality. Sensitivities and visual scores from both PETs and standalone MRI were compared using the McNemar test with Bonferroni correction and Dunn's multiple comparisons test. RESULTS: The EZs were confirmed histopathologically via resection as hippocampal sclerosis (n = 11, 35.5%), gliosis (n = 8, 25.8%), focal cortical dysplasia (n = 6, 19.4%), and brain tumours (n = 6, 19.4%) including cavernous haemangioma (n = 3), dysembryoplastic neuroepithelial tumour (n = 1), ganglioglioma (n = 1), and polymorphous low-grade neuroepithelial tumour of the young (n = 1). The sensitivity of FDG-PET/MRI was significantly higher than that of FDG-PET/CT and standalone MRI (FDG-PET/MRI vs. FDG-PET/CT vs. standalone MRI; 77.4-90.3% vs. 58.1-64.5% vs. 45.2-80.6%, p < 0.0001, respectively). The visual scores derived from FDG-PET/MRI were significantly higher than those of FDG-PET/CT, as well as standalone MRI (2.8 ± 1.2 vs. 2.0 ± 1.1 vs. 2.1 ± 1.2, p < 0.0001, respectively). Compared to FDG-PET/CT, FDG-PET/MRI increased the visual score (51.9%, increased visual scores of 2 and 3). CONCLUSIONS: The diagnostic accuracy for the EZ detection in focal epilepsy could be higher in FDG-PET/MRI than in FDG-PET/CT. KEY POINTS: • Sensitivity of FDG-PET/MRI was significantly higher than that of FDG-PET/CT and standalone MRI (FDG-PET/MRI vs. FDG-PET/CT vs. standalone MRI; 77.4-90.3% vs. 58.1-64.5% vs. 45.2-80.6%, p < 0.0001, respectively). • Visual scores derived from FDG-PET/MRI were significantly higher than those of FDG-PET/CT and standalone MRI (2.8 ± 1.2 vs. 2.0 ± 1.1 vs. 2.1 ± 1.2, p < 0.0001, respectively). • Compared to FDG-PET/CT, FDG-PET/MRI increased the visual score (51.9%, increased visual scores of 2 and 3)..
6. Ryoji Mikayama, Hidetake Yabuuchi, Ryoji Matsumoto, Koji Kobayashi, Yasuo Yamashita, Mitsuhiro Kimura, Takeshi Kamitani, Koji Sagiyama, Yuzo Yamasaki, Development of a new phantom simulating extracellular space of tumor cell growth and cell edema for diffusion-weighted magnetic resonance imaging., Magma (New York, N.Y.), 10.1007/s10334-019-00823-6, 33, 4, 507-513, 2020.08, OBJECTIVE: A phantom for diffusion-weighted imaging is required to standardize quantitative evaluation. The objectives were to develop a phantom simulating various cell densities and to evaluate repeatability. MATERIALS AND METHODS: The acrylic fine particles with three different diameters were used to simulate human cells. Four-degree cell density components were developed by adjusting the volume of 10-μm particles (5, 20, 35, and 50% volume, respectively). Two-degree components to simulate cell edema were also developed by adjusting the diameter without changing number (17% and 40% volume, respectively). Spearman's rank correlation coefficient was used to find a significant correlation between apparent diffusion coefficient (ADC) and particle density. Coefficient of variation (CV) for ADC was calculated for each component for 6 months. A p value < 0.05 represented a statistically significance. RESULTS: Each component (particle ratio of 5, 17, 20, 35, 40, and 50% volume, respectively) presented ADC values of 1.42, 1.30, 1.30, 1.12, 1.09, and 0.89 (× 10-3 mm2/s), respectively. A negative correlation (r =  - 0.986, p < 0.05) was observed between ADC values and particle ratio. CV for ADC was less than 5%. DISCUSSION: A phantom simulating the diffusion restriction correlating with cell density and size could be developed..
7. Takuya Hino, Takeshi Kamitani, Koji Sagiyama, Yuzo Yamasaki, Yuko Matsuura, Soichiro Tsutsui, Yuki Sakai, Tadashi Furuyama, Hidetake Yabuuchi, Detectability of the artery of Adamkiewicz on computed tomography angiography of the aorta by using ultra-high-resolution computed tomography., Japanese journal of radiology, 10.1007/s11604-020-00943-3, 38, 7, 658-665, 2020.07, PURPOSE: To evaluate the detectability of AKA on aortic computed tomography angiography (CTA) using ultra-high-resolution computed tomography (UHRCT). MATERIALS AND METHODS: Twenty-eight patients were enrolled. They underwent aortic CTA with UHRCT (UHRCTA) and had previously undergone aortic conventional CTA (CCTA). The injection protocol of UHRCTA was the same as that of CCTA. The bolus tracking technique was used. UHRCTA images were reconstructed with adaptive iterative dose reduction (strong) and with forward-projected model-based iterative reconstruction solution. The matrix size and slice thickness on UHRCT were 1024 and 0.25 mm, respectively, and those on conventional CT were 512 and 0.5 or 0.67 mm, respectively. The UHRCTA and CCTA images were visually compared by using four scales. A score of 4 or 3 indicated that the AKA was assessable. In this instance, the contrast-to-noise ratios of each UHRCTA were measured. The exposure dose and signal-to-noise ratios were also investigated. RESULTS: The AKA visualization scores obtained with UHRCTA with forward-projected model-based iterative reconstruction solution were significantly higher than those with adaptive iterative dose reduction (p = 0.018) and CCTA (p = 0.0024). CONCLUSION: UHRCT can contribute to the better visualization of the AKA on aortic CTA..
8. Ryoji Mikayama, Hidetake Yabuuchi, Ryoji Matsumoto, Koji Kobayashi, Yasuo Yamashita, Mitsuhiro Kimura, Takeshi Kamitani, Koji Sagiyama, Yuzo Yamasaki, Correction to: Development of a new phantom simulating extracellular space of tumor cell growth and cell edema for diffusion-weighted magnetic resonance imaging., Magma (New York, N.Y.), 10.1007/s10334-020-00830-y, 33, 4, 515-516, 2020.08, The original version of this article unfortunately contained a mistake. Second column of "Cell edema" should read as..
9. Hidetake Yabuuchi, Takeshi Kamitani, Koji Sagiyama, Yuzo Yamasaki, Tomoyuki Hida, Yuko Matsuura, Takuya Hino, Yuriko Murayama, Ryuji Yasumatsu, Hidetaka Yamamoto, Characterization of parotid gland tumors: added value of permeability MR imaging to DWI and DCE-MRI., European radiology, 10.1007/s00330-020-07004-3, 30, 12, 6402-6412, 2020.12, OBJECTIVES: To determine added value of permeability MRI in parotid tumor characterization to T2-weighted imaging (T2WI), semi-quantitative analysis of time-intensity curve (TIC), and intra-voxel incoherent motion diffusion-weighted imaging (IVIM-DWI). METHODS: This retrospective study was approved by the institutional review board, and the informed consent was waived. Sixty-one parotid tumors in 61 patients were examined using T2WI, IVIM-DWI, and permeability MRI. TIC patterns were categorized as persistent, washout, or plateau. Signal intensity ratio of lesion-to-muscle on T2WI, apparent diffusion coefficients (ADCs), D and f values from IVIM-DWI, and Ktrans, kep, Ve, and Vp values from permeability MRI were measured. Multiple comparisons were applied to determine whether any differences among 4 histopathologic types (pleomorphic adenomas, Warthin's tumors, other benign tumors, and malignant tumors) existed. Diagnostic accuracy was compared before and after modification diagnosis referring to permeability MRI. In a validation study, 60 parotid tumors in 60 patients were examined. RESULTS: ADC and D values of malignant tumors were significantly lower than those of benign tumors other than Warthin's tumors, but higher than those of Warthin's tumors. kep and Vp values of Warthin's tumors were significantly higher than those of malignant tumors. Multivariate analyses showed that TIC pattern, D, and kep values were suitable parameters. McNemar's test showed a significant increase of sensitivity (11/12, 92%) and specificity (46/49, 94%) with adding kep. The validation study yielded high sensitivity (14/16, 88%) and specificity (41/44, 93%). CONCLUSION: Permeability MRI offers added value to IVIM-MRI and semi-quantitative TIC analysis of DCE-MRI in characterization of parotid tumors KEY POINTS: • Permeability MR imaging offers added value in the characterization of parotid gland tumors in combination with semi-quantitative TIC analysis and IVIM analyses with D parameter. • The combination of TIC pattern, D, and kep might facilitate accurate characterization of parotid gland tumor, thereby avoiding unnecessary surgery for benign tumors or delayed treatment for malignant tumors. • A combination of permeability and diffusion MR imaging can be used to guide the selection of an appropriate biopsy site..
10. Yuzo Yamasaki, Kohtaro Abe, Takeshi Kamitani, Kazuya Hosokawa, Masateru Kawakubo, Koji Sagiyama, Tomoyuki Hida, Yuko Matsuura, Yuriko Murayama, Ryohei Funatsu, Hiroyuki Tsutsui, Hidetake Yabuuchi, Balloon pulmonary angioplasty improves right atrial reservoir and conduit functions in chronic thromboembolic pulmonary hypertension., European heart journal cardiovascular Imaging, 10.1093/ehjci/jeaa064, 21, 8, 855-862, 2020.08, AIMS: Right atrial (RA) function largely contributes to the maintenance of right ventricular (RV) function. This study investigated the effect of balloon pulmonary angioplasty (BPA) on RA functions in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH) using cardiac magnetic resonance imaging (CMRI). METHODS AND RESULTS: CMRI and RV catheterization were performed before BPA sessions and at the follow-up periods in 29 CTEPH patients. Reservoir [RA longitudinal strain (RA-LS)], passive conduit [RA early LS rate (LSR)], and active (RA late LSR) phases were assessed by using cine CMRI and a feature-tracking algorithm. The relationships between the changes in RA functions and in brain natriuretic peptide (BNP) were evaluated in both the dilated and non-dilated RA groups. RA-LS (32.4% vs. 42.7%), RA LSR (6.3% vs. 8.3%), and RA early LSR (-2.3% vs. -4.3%) were improved after BPA, whereas no significant change was seen in RA late LSR. The changes in RA peak LS and in RA early LSR were significantly correlated with the changes in BNP (ΔRA-LS: r = -0.63, ΔRA-early LSR: r = 0.65) and pulmonary vascular resistance (PVR) (ΔRA-LS: r = -0.69, ΔRA-early LSR: r = 0.66) in the nondilated RA group. CONCLUSION: The RA reservoir and passive conduit functions were impaired in inoperable CTEPH, whereas RA active function was preserved. BPA markedly reversed these impaired functions. The improvements in RA reservoir and conduit functions were significantly correlated with the changes in BNP levels and PVR in CTEPH patients with normal RA sizes..
11. Takeshi Kamitani, Koji Sagiyama, Osamu Togao, Yuzo Yamasaki, Tomoyuki Hida, Yuko Matsuura, Yuriko Murayama, Ryuji Yasumatsu, Hidetaka Yamamoto, Hidetake Yabuuchi, Amide proton transfer (APT) imaging of parotid tumors: Differentiation of malignant and benign tumors., European journal of radiology, 10.1016/j.ejrad.2020.109047, 129, 109047-109047, 2020.08, PURPOSE: To assess the usefulness of amide proton transfer (APT) imaging in differentiating parotid tumors. MATERIAL AND METHODS: We retrospectively analyzed 43 histopathologically proven parotid solid tumors with diameters ≥2 cm. Twenty-one tumors were benign and 12 tumors were malignant. Two-dimensional APT imaging was performed using a saturation pulse with a duration of 2 s and a saturation power level of 2 μT. For acquiring Z-spectra, the imaging was repeated at 25 saturation frequency offsets from ω = -6 to +6 ppm with a step of 0.5 ppm as well as one scan acquired far off-resonance (-1560 ppm) for signal normalization. For the APT imaging, the asymmetry analysis at 3.5 ppm downfield from the water signal was calculated. The mean APT signal intensity (SI) was compared between the benign and malignant tumors. RESULTS: The mean APT SI was 2.23 ± 0.80 % in the benign tumors and significantly higher at 2.99 ± 0.99 % in the malignant tumors (P = 0.01). A receiver operating curve analysis revealed that the optimal APT SI threshold was 2.40 for distinguishing malignant tumors from benign tumors with an area under the curve of 0.74. The sensitivity, specificity, and accuracy were 83.3%, 61.3%, and 67.4%, respectively. CONCLUSION: The mean APT SI of the malignant parotid tumors was significantly higher than that of the benign parotid tumors..
12. Masateru Kawakubo, Yuzo Yamasaki, Takeshi Kamitani, Koji Sagiyama, Yuko Matsuura, Takuya Hino, Kohtaro Abe, Kazuya Hosokawa, Hidetake Yabuuchi, Hiroshi Honda, Clinical usefulness of right ventricular 3D area strain in the assessment of treatment effects of balloon pulmonary angioplasty in chronic thromboembolic pulmonary hypertension: comparison with 2D feature-tracking MRI., European radiology, 10.1007/s00330-019-6008-3, 29, 9, 4583-4592, 2019.09, OBJECTIVES: To evaluate the usefulness of right ventricular (RV) area strain analysis via cardiac MRI (CMRI) as a tool for assessing the treatment effects of balloon pulmonary angioplasty (BPA) in inoperable chronic thromboembolic pulmonary hypertension (CTEPH), RV area strain was compared to two-dimensional (2D) strain with feature-tracking MRI (FTMRI) before and after BPA. METHODS: We retrospectively analyzed 21 CTEPH patients who underwent BPA. End-systolic global area strain (GAS), longitudinal strain (LS), circumferential strain (CS), and radial strain (RS) were measured before and after BPA. Changes in GAS and RV ejection fraction (RVEF) values after BPA were defined as ΔGAS and ΔRVEF. Receiver operating characteristic (ROC) analyses were performed to determine the optimal cutoff of the strain at after BPA for detection of improved patients with decreased mean pulmonary artery pressure (mPAP) less than 30 mmHg and increased RVEF more than 50%. RESULTS: ROC analysis revealed the optimal cutoffs of strains (GAS, LS, CS, and RS) for identifying improved patients with mPAP < 30 mmHg (cutoff (%) = - 41.2, - 13.8, - 16.7, and 14.4: area under the curve, 0.75, 0.56, 0.65, and 0.75) and patients with RVEF > 50% (cutoff (%) = - 37.2, - 29.5, - 2.9, and 14.4: area under the curve, 0.81, 0.60, 0.56, and 0.56). CONCLUSIONS: Area strain analysis via CMRI may be a more useful tool for assessing the treatment effects of BPA in patients with CTEPH than 2D strains with FTMRI. KEY POINTS: • Area strain values can detect improvement of right ventricular (RV) pressure and function after balloon pulmonary angioplasty (BPA) equally or more accurately than two-dimensional strains. • Area strain analysis is a useful analytical method that reflects improvements in complex RV myocardial deformation by BPA. • Area strain analysis is a robust method with reproducibility equivalent to that of 2D strain analysis..
13. Mitsuhiro Kimura, Hidetake Yabuuchi, Ryoji Matsumoto, Koji Kobayashi, Yasuo Yamashita, Kazuya Nagatomo, Ryoji Mikayama, Takeshi Kamitani, Koji Sagiyama, Yuzo Yamasaki, The reproducibility of measurements using a standardization phantom for the evaluation of fractional anisotropy (FA) derived from diffusion tensor imaging (DTI)., Magma (New York, N.Y.), 10.1007/s10334-019-00776-w, 33, 2, 293-298, 2020.04, OBJECTIVES: It is necessary to standardize the examination procedure and diagnostic criteria of diffusion tensor imaging (DTI). Thus, the purpose of this study was to examine the reproducibility of measurements using a standardization phantom composed of different fibre materials with different fibre densities (FDs) for the evaluation of fractional anisotropy (FA) derived from DTI. MATERIALS AND METHODS: Two types of fibre materials wrapped in heat-shrinkable tubes were used as fibre phantoms. We designed fibre phantoms with three different FDs of each fibre material. The standardization phantom was examined using DTI protocol six times a day, and each examination session was repeated once a month for 7 consecutive months. Fibre tracking was performed by setting regions of interest in the FA map, and FA was measured in each fibre phantom. Coefficients of variation (CVs) were used to evaluate the inter-examination reproducibility of FA values. Furthermore, Bland-Altman plots were used to evaluate the intra-operator reproducibility of FA measurements. RESULTS: All CVs for each fibre phantom were within 2% throughout the 7-month study of repeated DTI sessions. The high intra-operator reproducibility of the FA measurement was confirmed. DISCUSSION: High reproducibility of measurements using a standardization phantom for the evaluation of FA was achieved..
14. Takamitsu Okada, Hidehiko Yuge, Takeshi Kamitani, Takahiro Senju, Naohide Takeuchi, Koji Sagiyama, Naoya Kozono, Yoshitaka Nakanishi, Hiroshi Honda, Yasuharu Nakashima, Evaluation of humeral head cartilage using magnetic resonance imaging T1 rho mapping for patients with small-to-medium rotator cuff tears: A pilot study., Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association, 10.1016/j.jos.2018.10.002, 24, 2, 258-262, 2019.03, BACKGROUND: It is unclear whether smaller rotator cuff tears cause cartilage degeneration. This study was designed to detect early humeral head cartilage degeneration in patients with small-to-medium cuff tears using magnetic-resonance-imaging T1 rho mapping. METHODS: Five male and 5 female volunteers without shoulder symptoms (control group) and 5 male and 5 female patients with small-to-medium (<3 cm) rotator cuff tears underwent 3.0-T magnetic resonance imaging of a single shoulder. T1 rho values of the humeral head cartilage were measured and analyzed. RESULTS: The total mean T1 rho value was 40.4 ± 3.4 ms for the control group and 45.0 ± 5.3 ms for the patient group. In the control group, the T1 rho values in the inferior articular cartilage were significantly higher than those in the superior and middle articular cartilage. In the patient group, there was no significant difference between all regions. A comparison between the patient and control groups showed that the mean T1 rho values in the superior-to-middle articular cartilage were significantly higher for the patient group than for the control group. However, in the inferior articular cartilage, there was no significant difference between both groups. CONCLUSIONS: This study showed the possibility of early cartilage degenerative changes in the superior-to-middle humeral head articular cartilage of patients with small-to-medium rotator cuff tears..
15. Akihiro Nishie, Yoshiki Asayama, Kousei Ishigami, Yasuhiro Ushijima, Yukihisa Takayama, Daisuke Okamoto, Nobuhiro Fujita, Daisuke Tsurumaru, Osamu Togao, Koji Sagiyama, Tatsuya Manabe, Eiji Oki, Yuichiro Kubo, Tomoyuki Hida, Minako Hirahashi-Fujiwara, Jochen Keupp, Hiroshi Honda, Amide proton transfer imaging to predict tumor response to neoadjuvant chemotherapy in locally advanced rectal cancer., Journal of gastroenterology and hepatology, 10.1111/jgh.14315, 34, 1, 140-146, 2019.01, BACKGROUND AND AIM: The amount of proteins and peptides can be estimated with amide proton transfer (APT) imaging. Previous studies demonstrated the usefulness of APT imaging to predict tumor malignancy. We determined whether APT imaging can predict the tumor response to neoadjuvant chemotherapy (NAC) in patients with locally advanced rectal cancer (LARC). METHODS: Seventeen patients with LARC who underwent a pretherapeutic magnetic resonance examination including APT imaging and NAC (at least two courses) were enrolled. The APT-weighted imaging (WI) signal intensity (SI) (%) was defined as magnetization transfer ratio asymmetry (MTRasym ) at the offset of 3.5 ppm. Each tumor was histologically evaluated for the degree of degeneration and necrosis and then classified as one of five histological Grades (0, none; 1a, less than 1/3; 1b, 1/3 to 2/3; 2, more than 2/3; 3, all). We compared the mean APTWI SIs of the tumors between the Grade 0/1a/1b (low-response group) and Grade 2/3 (high-response group) by Student's t-test. We used receiver operating characteristics curves to determine the diagnostic performance of the APTWI SI for predicting the tumor response. RESULTS: The mean APTWI SI of the low-response group (n = 12; 3.05 ± 1.61%) was significantly higher than that of the high-response group (n = 5; 1.14 ± 1.13%) (P = 0.029). The area under the curve for predicting the tumor response using the APTWI SI was 0.87. When ≥2.75% was used as an indicator of low-response status, 75% sensitivity and 100% specificity of the APTWI SI were obtained. CONCLUSION: Pretherapeutic APT imaging can predict the tumor response to NAC in patients with LARC..
16. Tetsuro Ushio, Ken Okazaki, Kanji Osaki, Yukihisa Takayama, Koji Sagiyama, Hideki Mizu-Uchi, Satoshi Hamai, Yukio Akasaki, Hiroshi Honda, Yasuharu Nakashima, Degenerative changes in cartilage likely occur in the medial compartment after anterior cruciate ligament reconstruction., Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 10.1007/s00167-019-05468-5, 27, 11, 3567-3574, 2019.11, PURPOSE: Magnetic resonance imaging with T1ρ mapping is used to quantify the amount of glycosaminoglycan in articular cartilage, which reflects early degenerative changes. The purposes of this study were to evaluate early degenerative changes in knees after anterior cruciate ligament (ACL) reconstruction by comparing T1ρ values before and 2 years after surgery and investigate whether surgical factors and clinical outcomes are related to differences in T1ρ values. METHODS: Fifty patients who underwent unilateral primary ACL reconstruction were evaluated using T1ρ mapping before and 2 years after surgery. Three regions of interest (ROIs) were defined in the cartilage associated with the medial (M) and lateral (L) weight-bearing areas of the femoral condyle (FC) (anterior: MFC1 and LFC1, middle: MFC2 and LFC2, and posterior: MFC3 and LFC3). Two ROIs associated with the tibial plateau (T) were defined (anterior: MT1 and LT1, and posterior: MT2 and LT2). T1ρ values within the ROIs were measured before and 2 years after surgery and compared using the paired t test. Correlations between the difference in T1ρ values at these two time points and patient characteristics, presence of a cartilaginous lesion, graft type, and postoperative anteroposterior laxity were also evaluated using Pearson's and Spearman's correlation coefficients. RESULTS: There was a significant increase in T1ρ before versus 2 years after surgery in the MT1, MT2, LFC1, and LT1 areas, and a significant decrease in the LFC3 and LT2 areas. There was a significant correlation between postoperative anterior-posterior laxity and a postoperative increase in T1ρ values in the MFC3 (r = 0.37, P = 0.013) and MT2 (r = 0.35, P = 0.021) areas. Increases in T1ρ values in the MFC2 area were negatively correlated with KOOS symptoms (ρ = - 0.349, P = 0.027) and quality of life (ρ = - 0.374, P = 0.017) subscale scores. CONCLUSION: Early degenerative changes in medial articular cartilage were observed with T1ρ mapping at 2 years after ACL reconstruction. Postoperative anterior-posterior laxity is correlated with an increase in T1ρ values in the posteromedial femur and tibia. An increase in T1ρ values in the central medial femoral condyle was associated with knee symptoms. LEVEL OF EVIDENCE: III..
17. Takuya Hino, Takeshi Kamitani, Koji Sagiyama, Yuzo Yamasaki, Isamu Okamoto, Tetsuzo Tagawa, Kayo Ijichi, Hidetaka Yamamoto, Hidetake Yabuuchi, Hiroshi Honda, Localized malignant pleural mesothelioma mimicking an anterior mediastinal tumor, European Journal of Radiology Open, 10.1016/j.ejro.2019.01.006, 6, 72-77, 2019.01, Localized malignant pleural mesothelioma (LMPM) is an extremely rare tumor. We report the case of a 40-year-old Japanese male with an LMPM mimicking an anterior mediastinal tumor due to invasion to the anterior mediastinum, and we discuss mainly the differentiation of LMPM from an anterior mediastinal tumor. The present tumor had a long shape along the pleura, and LMPM could be one of the differential diagnoses..
18. Hidetake Yabuuchi, Takeshi Kamitani, Koji Sagiyama, Yuzo Yamasaki, Yuko Matsuura, Takuya Hino, Soichiro Tsutsui, Masatoshi Kondo, Takashi Shirasaka, Hiroshi Honda, Clinical application of radiation dose reduction for head and neck CT., European journal of radiology, 10.1016/j.ejrad.2018.08.021, 107, 209-215, 2018.10, CT has advantages over MRI including rapid acquisition, and high spatial resolution for detailed anatomical information on the head and neck region. Therefore, CT is the first choice of imaging modality for the larynx, hypopharynx, sinonasal region, and temporal bone. Introduction of multi-detector CT (MDCT) scanning has allowed reduction in scan time, availability of isovoxel image, and relevant 3D image reconstruction; however, it leads to over-ranging due to helical scanning, and increased radiation dose due to 3D-volume imaging, and small detector size. In head and neck CT, reduction and optimization of radiation dose is very important, especially for prevention of the occurrence of cataract development due to radiation to lens, and prevention of the development of malignant tumour development from radiosensitive organs such as the salivary gland, thyroid gland, and retina, especially in children. The goal of dose reduction is "as low as reasonably achievable" (ALARA) level with preservation of appropriate image quality in clinical practice. Reduction of radiation dose per examination is essential; however, indication of repeat examination such as perfusion CT, dynamic contrast-enhanced CT, and follow-up study of malignant tumours should be optimized..
19. Yuzo Yamasaki, Satoshi Kawanami, Takeshi Kamitani, Koji Sagiyama, Seitaro Shin, Takuya Hino, Hazumu Nagata, Hidetake Yabuuchi, Michinobu Nagao, Hiroshi Honda, Patient-related factors influencing detectability of coronary arteries in 320-row CT angiography in infants with complex congenital heart disease., The international journal of cardiovascular imaging, 10.1007/s10554-018-1363-8, 34, 9, 1485-1491, 2018.09, To investigate the performance of second-generation 320-row computed tomographic (CT) angiography (CTA) in detecting coronary arteries and identify factors influencing visibility of the coronary arteries in infants with complex congenital heart disease (CHD). Data of 60 infants (aged 0-2 years, median 2 months) with complex CHD who underwent examination using 320-row CTA with low-dose prospective electrocardiogram-triggered volume target scanning were reviewed. The coronary arteries of each infant were assessed using a 0-4-point scoring system based on the number of coronary segments with a visible course. Clinical parameters, the CT value in the ascending aorta, image noise, and the radiation dose were subjected to univariate and multivariate analyses. The mean coronary score for all examinations was 2.6 ± 1.5 points. The mean attenuation in the ascending aorta was 306.7 ± 66.2 HU and the mean standard deviation was 21.7 ± 4.4. The mean effective radiation dose was 1.27 ± 0.39 mSv. Multivariate regression analysis showed significant correlations between coronary score and body weight (p < 0.05) and between coronary score and the CT value in the ascending aorta (p < 0.02). Second-generation 320-row CTA with prospective electrocardiogram-triggered volume target scanning and hybrid iterative reconstruction allows good visibility of the coronary arteries in infants with complex CHD. Body weight and the CT value in the ascending aorta are important factors influencing the visibility of the coronary arteries in infants..
20. Ryotaro Kamei, Yuji Watanabe, Koji Sagiyama, Takuro Isoda, Osamu Togao, Hiroshi Honda, Optimal monochromatic color combinations for fusion imaging of FDG-PET and diffusion-weighted MR images., Annals of nuclear medicine, 10.1007/s12149-018-1263-y, 32, 7, 437-445, 2018.08, OBJECTIVE: To investigate the optimal monochromatic color combination for fusion imaging of FDG-PET and diffusion-weighted MR images (DW) regarding lesion conspicuity of each image. METHODS: Six linear monochromatic color-maps of red, blue, green, cyan, magenta, and yellow were assigned to each of the FDG-PET and DW images. Total perceptual color differences of the lesions were calculated based on the lightness and chromaticity measured with the photometer. Visual lesion conspicuity was also compared among the PET-only, DW-only and PET-DW-double positive portions with mean conspicuity scores. Statistical analysis was performed with a one-way analysis of variance and Spearman's rank correlation coefficient. RESULTS: Among all the 12 possible monochromatic color-map combinations, the 3 combinations of red/cyan, magenta/green, and red/green produced the highest conspicuity scores. Total color differences between PET-positive and double-positive portions correlated with conspicuity scores (ρ = 0.2933, p < 0.005). Lightness differences showed a significant negative correlation with conspicuity scores between the PET-only and DWI-only positive portions. Chromaticity differences showed a marginally significant correlation with conspicuity scores between DWI-positive and double-positive portions. CONCLUSIONS: Monochromatic color combinations can facilitate the visual evaluation of FDG-uptake and diffusivity as well as registration accuracy on the FDG-PET/DW fusion images, when red- and green-colored elements are assigned to FDG-PET and DW images, respectively..
21. Yuzo Yamasaki, Satoshi Kawanami, Takeshi Kamitani, Koji Sagiyama, Seitaro Shin, Takuya Hino, Kenichiro Yamamura, Hidetake Yabuuchi, Michinobu Nagao, Hiroshi Honda, Free-breathing 320-row computed tomographic angiography with low-tube voltage and hybrid iterative reconstruction in infants with complex congenital heart disease, Clinical Imaging, 10.1016/j.clinimag.2018.02.008, 50, 147-156, 2018.07, We explored the clinical value of low-tube voltage prospective second-generation ECG-triggered 320-row CT angiography in infants with complex CHD (37 male, 23 female, aged 0–2 years). The diagnostic accuracy of 320-row CT in complex CHD was 99.4% for intracardiac cardiovascular malformations, 99.8% for extracardiac cardiovascular malformations, and 100% for other malformations. The average subjective overall image quality score for cardiac structures was 3.7 ± 0.5 points. Second-generation 320-row CT angiography with low-tube voltage and prospective ECG-triggered volume target scanning allows accurate diagnosis of cardiovascular anomalies in infants with complex CHD..
22. Yuzo Yamasaki, Satoshi Kawanami, Takeshi Kamitani, Koji Sagiyama, Ichiro Sakamoto, Ken-Ichi Hiasa, Hidetake Yabuuchi, Michinobu Nagao, Hiroshi Honda, Noninvasive quantification of left-to-right shunt by phase contrast magnetic resonance imaging in secundum atrial septal defect: the effects of breath holding and comparison with invasive oximetry., The international journal of cardiovascular imaging, 10.1007/s10554-018-1297-1, 34, 6, 931-937, 2018.06, To investigate the effect of breath-holding on left-to-right shunts in patients with a secundum atrial septal defect (ASD). Thirty-five consecutive patients with secundum ASDs underwent right heart catheterization and invasive oximetry. Phase-contrast magnetic resonance imaging (MRI) was performed for the main pulmonary artery and ascending aorta. All measurements were obtained during free breathing (FB) (quiet breathing; no breath-hold), expiratory breath-hold (EBH), and inspiratory breath-hold (IBH). Pulmonary circulation flow (Qp) and systemic circulation flow (Qs) were calculated by multiplying the heart rate by the stroke volume. Measurements during FB, EBH, and IBH were compared, and the differences compared to invasive oximetry were evaluated. There were significant differences among the measurements during FB, EBH, and IBH for Qp (FB, 7.70 ± 2.68; EBH, 7.18 ± 2.34; IBH, 6.88 ± 2.51 l/min); however, no significant difference was found for Qs (FB, 3.44 ± 0.74; EBH, 3.40 ± 0.83; IBH, 3.40 ± 0.86 l/min). There were significant differences among the measurements during FB, EBH, and IBH for Qp/Qs (FB, 2.38 ± 1.12; EBH, 2.24 ± 0.95; IBH, 2.14 ± 0.97). Qp/Qs during FB and EBH correlated better with Qp/Qs measured by invasive oximetry than did IBH. The limit of agreement was smaller for EBH than for FB and IBH. In patients with secundum ASDs, Qp/Qs significantly decreased with breath-holding. The accuracy of the Qp/Qs measurement by MRI compared with invasive oximetry during EBH was higher than during FB and IBH..
23. Hidetake Yabuuchi, Satoshi Kawanami, Eiji Iwama, Isamu Okamoto, Takeshi Kamitani, Koji Sagiyama, Yuzo Yamasaki, Hiroshi Honda, Prediction of Therapeutic Effect of Chemotherapy for NSCLC Using Dual-Input Perfusion CT Analysis: Comparison among Bevacizumab Treatment, Two-Agent Platinum-based Therapy without Bevacizumab, and Other Non-Bevacizumab Treatment Groups., Radiology, 10.1148/radiol.2017162204, 286, 2, 685-695, 2018.02, Purpose To determine whether dual-input perfusion computed tomography (CT) can predict therapeutic response and prognosis in patients who underwent chemotherapy for non-small cell lung cancer (NSCLC). Materials and Methods The institutional review board approved this study and informed consent was obtained. Sixty-six patients with stage III or IV NSCLC (42 men, 24 women; mean age, 63.4 years) who underwent chemotherapy were enrolled. Patients were separated into three groups: those who received chemotherapy with bevacizumab (BV) (n = 20), those who received two-agent platinum-based therapy without BV (n = 25), and those who received other non-BV treatment (n = 21). Before treatment, pulmonary artery perfusion (PAP) and bronchial artery perfusion (BAP) of the tumors were calculated. Predictors of tumor reduction after two courses of chemotherapy and prognosis were identified by using univariate and multivariate analyses. Covariates included were age, sex, patient's performance status, baseline maximum diameter of the tumor, clinical stage, pretreatment PAP, and pretreatment BAP. For multivariate analyses, multiple linear regression analysis for tumor reduction rate and Cox proportional hazards model for prognosis were performed, respectively. Results Pretreatment BAP was independently correlated with tumor reduction rate after two courses of chemotherapy in the BV treatment group (P = .006). Pretreatment BAP was significantly associated with a highly cumulative risk of death (P = .006) and disease progression after chemotherapy (P = .015) in the BV treatment group. Pretreatment PAP and clinical parameters were not significant predictors of therapeutic effect or prognosis in three treatment groups. Conclusion Pretreatment BAP derived from dual-input perfusion CT seems to be a promising tool to help predict responses to chemotherapy with BV in patients with NSCLC. © RSNA, 2017..
24. Koji Sagiyama, Yuji Watanabe, Ryotaro Kamei, Sungtak Hong, Satoshi Kawanami, Yoshihiro Matsumoto, Hiroshi Honda, Multiparametric voxel-based analyses of standardized uptake values and apparent diffusion coefficients of soft-tissue tumours with a positron emission tomography/magnetic resonance system: Preliminary results, EUROPEAN RADIOLOGY, 10.1007/s00330-017-4912-y, 27, 12, 5024-5033, 2017.12, To investigate the usefulness of voxel-based analysis of standardized uptake values (SUVs) and apparent diffusion coefficients (ADCs) for evaluating soft-tissue tumour malignancy with a PET/MR system.
Thirty-five subjects with either ten low/intermediate-grade tumours or 25 high-grade tumours were prospectively enrolled. Zoomed diffusion-weighted and fluorodeoxyglucose ((18)FDG)-PET images were acquired along with fat-suppressed T2-weighted images (FST2WIs). Regions of interest (ROIs) were drawn on FST2WIs including the tumour in all slices. ROIs were pasted onto PET and ADC-maps to measure SUVs and ADCs within tumour ROIs. Tumour volume, SUVmax, ADCminimum, the heterogeneity and the correlation coefficients of SUV and ADC were recorded. The parameters of high- and low/intermediate-grade groups were compared, and receiver operating characteristic (ROC) analysis was also performed.
The mean correlation coefficient for SUV and ADC in high-grade sarcomas was lower than that of low/intermediate-grade tumours (-0.41 +/- 0.25 vs. -0.08 +/- 0.34, P < 0.01). Other parameters did not differ significantly. ROC analysis demonstrated that correlation coefficient showed the best diagnostic performance for differentiating the two groups (AUC 0.79, sensitivity 96.0%, specificity 60%, accuracy 85.7%).
SUV and ADC determined via PET/MR may be useful for differentiating between high-grade and low/intermediate-grade soft tissue tumours.
aEuro cent PET/MR allows voxel-based comparison of SUVs and ADCs in soft-tissue tumours.
aEuro cent A comprehensive assessment of internal heterogeneity was performed with scatter plots.
aEuro cent SUVmax or ADCminimum could not differentiate high-grade sarcoma from low/intermediate-grade tumours.
aEuro cent Only the correlation coefficient between SUV and ADC differentiated the two groups.
aEuro cent The correlation coefficient showed the best diagnostic performance by ROC analysis..
25. Michinobu Nagao, Yuzo Yamasaki, Satoshi Kawanami, Takeshi Kamitani, Koji Sagiyama, Taiki Higo, Tomomi Ide, Atsushi Takemura, Umiko Ishizaki, Kenji Fukushima, Yuji Watanabe, Hiroshi Honda, Quantification of myocardial oxygenation in heart failure using blood-oxygen-level-dependent T2*magnetic resonance imaging: Comparison with cardiopulmonary exercise test, MAGNETIC RESONANCE IMAGING, 10.1016/j.mri.2017.02.005, 39, 138-143, 2017.06, Purpose: Quantification of myocardial oxygenation (MO) in heart failure (HF) has been less than satisfactory. This has necessitated the use of invasive techniques to measure MO directly or to determine the oxygen demand during exercise using the cardiopulmonary exercise (CPX) test. We propose a new quantification method for MO using blood-oxygen-level-dependent (BOLD) myocardial T2* magnetic resonance imaging (M-T2* MRI), and investigate its correlation with CPX results.
Methods: Thirty patients with refractory HF who underwent cardiac MRI and CPX test for heart transplantation, and 24 healthy, age-matched volunteers as controls were enrolled. M-T2* imaging was performed using a 3-Tesla and multi-echo gradient-echo sequence. M-T2* was calculated by fitting the signal intensity data for the mid-left ventricular septum to a decay curve. M-T2* was measured under room-air (T2*-air) and after inhalation of oxygen for 10 min at a flow rate of 10 L/min (T2*-oxy). MO was defined as the difference between the two values (AT2*). Changes in M-T2* at the two conditions and AT2* between the two groups were compared. Correlation between AT2* and CPX results was analyzed using the Pearson coefficient.
Results: T2*-oxy was significantly greater than T2*-air in patients with HF (29.9 +/- 7.3 ms vs. 26.7 +/- 6.0 ms, p < 0.001), whereas no such difference was observed in controls (25.5 +/- 4.0 ms vs. 25.4 +/- 4.4 ms)..6,T2* was significantly greater for patients with HF than for controls (3.2 +/- 4.5 ms vs.-0.1 +/- 13 ms, p < 0.001). A significant correlation between AT2* and CPX results (peak V02, r = 0.46, p < 0.05; 02 pulse, r = 0.54, p < 0.005) was observed.
Conclusion: AT2* is increased T2*-oxy is greater in patients with HF, and is correlated with oxygen metabolism during exercise as measured by the CPX test. Hence, AT2* can be used as a surrogate marker of MO instead of CPX test. (C) 2017 Elsevier Inc. All rights reserved..
26. Yuzo Yamasaki, Michinobu Nagao, Satoshi Kawanami, Takeshi Kamitani, Koji Sagiyama, Torahiko Yamanouchi, Ichiro Sakamoto, Kenichiro Yamamura, Hidetake Yabuuchi, Hiroshi Honda, One-stop shop assessment for atrial septal defect closure using 256-slice coronary CT angiography, EUROPEAN RADIOLOGY, 10.1007/s00330-016-4407-2, 27, 2, 697-704, 2017.02, To investigate the feasibility and accuracy of measurement of the pulmonary to systemic blood flow ratio (Qp/Qs) and defect and rim sizes in secundum atrial septal defects (ASDs) using 256-slice CT, compared to the reference transoesophageal echocardiography (TEE) and right heart catheterization (RHC) measurements.
Twenty-three consecutive adult patients with secundum ASDs who underwent retrospective ECG-gated coronary CT angiography (CCTA), TEE and RHC were enrolled in this study. Right ventricular (RV) and left ventricular (LV) stroke volumes (SV) were calculated by biventricular volumetry of CCTA. Qp/Qs-CT was defined as RVSV/LVSV. The sizes of the defect and rim were measured by multi-planar reconstruction CT images. Correlations between Qp/Qs-CT and Qp/Qs-RHC and between the defect diameter obtained by CT and TEE were analyzed by Pearson's coefficient analysis. Rim sizes by CT and TEE were compared by paired t-test.
Qp/Qs-CT was significantly correlated with Qp/Qs-RHC (r = 0.83, p < 0.0001), and the defect diameter by CT was significantly correlated with that by TEE (r = 0.95, p < 0.0001). There was no significant difference between CT and TEE in measurements of rim size.
256-slice CCTA allows measuring Qp/Qs and size of defects and rims in patients with secundum ASDs, accomplishing pretreatment evaluation non-invasively and comprehensively.
aEuro cent Quantification of left-to-right shunting can be performed reliably and accurately by CT.
aEuro cent The sizes of defects and rims can be measured accurately using 256-slice CT.
aEuro cent 256-slice CT permits pretreatment evaluation of ASD non-invasively and comprehensively..
27. Torahiko Yamanouchi, Satoshi Kawanami, Takeshi Kamitani, Koji Sagiyama, Yuzo Yamasaki, Yuko Tanaka, Michinobu Nagao, Hidetake Yabuuchi, Naoki Hamada, Tatsuro Okamoto, Hidetaka Yamamoto, Hiroshi Honda, Lymphomatoid Granulomatosis Two Different Phenotypes of Computed Tomography Findings, JOURNAL OF THORACIC IMAGING, 10.1097/RTI.0000000000000243, 31, 6, W80-W82, 2016.11.
28. Osamu Togao, Akio Hiwatashi, Jochen Keupp, Koji Yamashita, Kazufumi Kikuchi, Takashi Yoshiura, Masami Yoneyama, Marijn J. Kruiskamp, Koji Sagiyama, Masaya Takahashi, Hiroshi Honda, Amide Proton Transfer Imaging of Diffuse Gliomas: Effect of Saturation Pulse Length in Parallel Transmission-Based Technique, PLOS ONE, 10.1371/journal.pone.0155925, 11, 5, e0155925, 2016.05, In this study, we evaluated the dependence of saturation pulse length on APT imaging of diffuse gliomas using a parallel transmission-based technique. Twenty-two patients with diffuse gliomas (9 low-grade gliomas, LGGs, and 13 high-grade gliomas, HGGs) were included in the study. APT imaging was conducted at 3T with a 2-channel parallel transmission scheme using three different saturation pulse lengths (0.5 s, 1.0 s, 2.0 s). The 2D fast spin-echo sequence was used for imaging. Z-spectrum was obtained at 25 frequency offsets from -6 to +6 ppm (step 0.5 ppm). A point-by-point B0 correction was performed with a B0 map. Magnetization transfer ratio (MTRasym) and Delta MTRasym (contrast between tumor and normal white matter) at 3.5 ppm were compared among different saturation lengths. A significant increase in MTRasym (3.5 ppm) of HGG was found when the length of saturation pulse became longer (3.09 +/- 0.54% at 0.5 s, 3.83 +/- 0.67% at 1 s, 4.12 +/- 0.97% at 2 s), but MTRasym (3.5 ppm) was not different among the saturation lengths in LGG Delta MTRasym (3.5 ppm) increased with the length of saturation pulse in both LGG (0.48 +/- 0.56% at 0.5 s, 1.28 +/- 0.56% at 1 s, 1.88 +/- 0.56% at 2 s and HGG (1.72 +/- 0.54% at 0.5 s, 2.90 +/- 0.49% at 1 s, 3.83 +/- 0.88% at 2 s). In both LGG and HGG, APT-weighted contrast was enhanced with the use of longer saturation pulses..
29. Michinobu Nagao, Yuzo Yamasaki, Takeshi Kamitani, Satoshi Kawanami, Koji Sagiyama, Torahiko Yamanouchi, Yamato Shimomiya, Tetsuya Matoba, Yasushi Mukai, Keita Odashiro, Shingo Baba, Yasuhiro Maruoka, Yoshiyuki Kitamura, Akihiro Nishie, Hiroshi Honda, Quantification of coronary flow using dynamic angiography with 320-detector row CT and motion coherence image processing: Detection of ischemia for intermediate coronary stenosis, EUROPEAN JOURNAL OF RADIOLOGY, 10.1016/j.ejrad.2016.02.027, 85, 5, 996-1003, 2016.05, Objectives: Anatomical coronary stenosis is not always indicative of functional stenosis, particularly for intermediate coronary lesions. The purpose of this study is to propose a new method for quantifying coronary flow using dynamic CT angiography for the whole heart (heart-DCT) and investigate its ability for detecting ischemia from intermediate coronary stenosis.
Methods: Participants comprised 36 patients with coronary artery disease who underwent heart-DCT using 320 -detector CT with tube voltage of 80 kV and myocardial perfusion scintigraphy (MPS). Heart-DCT was continuously performed at mid -diastole throughout 15-25 cardiac cycles with prospective ECG-gating after bolus injection of contrast media (12-24m1). Dynamic datasets were computed into 90-100 data sets by motion coherence image processing (MCIP). Next, time-density curves (TDCs) for coronary arteries with a diameter >3 mm were automatically calculated for all phases using MCIP. On the basis of the maximum slope method, coronary flow index (CFI) was defined as the ratio of the maximum upslope of coronary artery attenuation to the upslope of ascending aorta attenuation on the TDC, and was used to quantify coronary flow. CFIs for the proximal and distal sites of coronary arteries with mild -to moderate stenosis were calculated. Coronary territories were categorized as non-ischemic or ischemic by MPS. Receiver-operating -characteristic (ROC) analysis was performed to determine the optimal cutoff for CFI to detect ischemia.
Results: Distal CFI was significantly lower for ischemia (0.26 +/- 0.08) than for non-ischemia (0.50 +/- 0.17, p < 0.0001). No significant difference in proximal CFI was seen between ischemia (0.55 +/- 0.23) and nonischemia (0.62 +/- 0.24). ROC analysis revealed 0.39 as the optimal cutoff for distal CFI to detect ischemia, with C-statistics of 0.91, 100% sensitivity, and 75% specificity.
Conclusions: This novel imaging technique allows coronary flow quantification using heart-DCT. Distal CFI can detect myocardial ischemia derived from intermediate coronary stenosis. (C) 2016 Elsevier Ireland Ltd. All rights reserved..
30. Koji Sagiyama, Yuji Watanabe, Ryotaro Kamei, Daiki Shinyama, Shingo Baba, Hiroshi Honda, An improved MR sequence for attenuation correction in PET/MR hybrid imaging, MAGNETIC RESONANCE IMAGING, 10.1016/j.mri.2015.10.037, 34, 3, 345-352, 2016.04, The aim of this study was to investigate the effects of MR parameters on tissue segmentation and determine the optimal MR sequence for attenuation correction in PET/MR hybrid imaging. Eight healthy volunteers were examined using a PET/MR hybrid scanner with six three-dimensional turbo-field-echo sequences for attenuation correction by modifying the echo time, k-space trajectory in the phase-encoding direction, and image contrast. MR images for attenuation correction were obtained from six MR sequences in each session; each volunteer underwent four sessions. Two radiologists assessed the attenuation correction maps generated from the MR images with respect to segmentation errors and ghost artifacts on a five-point scale, and the scores were decided by consensus. Segmentation accuracy and reproducibility were compared. Multiple regression analysis was performed to determine the effects of each MR parameter. The two three-dimensional turbo-field-echo sequences with an in-phase echo time and radial k-space sampling showed the highest total scores for segmentation accuracy, with a high reproducibility. In multiple regression analysis, the score with the shortest echo time (-3.44, P < 0.0001) and Cartesian sampling in the anterior/posterior phase-encoding direction (-2.72, P = 0.002) was significantly lower than that with in-phase echo time and Cartesian sampling in the right/left phase-encoding direction. Radial k-space sampling provided a significantly higher score (+5.08, P < 0.0001) compared with Cartesian sampling. Furthermore, radial sampling improved intrasubject variations in the segmentation score (-828%, P = 0.002). Image contrast had no significant effect on the total score or reproducibility. These results suggest that three-dimensional turbo-field-echo MR sequences with an in-phase echo time and radial k-space sampling provide improved MR-based attenuation correction maps. (C) 2015 Elsevier Inc. All rights reserved..
31. Koji Sagiyama, Yuji Watanabe, Ryotaro Kamei, Shingo Baba, Hiroshi Honda, Comparison of positron emission tomography diffusion-weighted imaging (PET/DWI) registration quality in a PET/MR scanner: Zoomed DWI vs. Conventional DWI, JOURNAL OF MAGNETIC RESONANCE IMAGING, 10.1002/jmri.25059, 43, 4, 853-858, 2016.04, PurposeTo compare zoomed diffusion-weighted imaging (z-DWI) with reduced field of view (FOV) by spatially selective radiofrequency pulses and conventional echo planar imaging (EPI) DWI (c-DWI) with regard to registration quality using positron emission tomography / magnetic resonance (PET/MR) in patients with malignant tumors.
Materials and MethodsFludeoxyglucose (18(F)) PET imaging, c-DWI, and z-DWI were conducted simultaneously in 21 patients with known or suspected malignancy using a PET/MR system. A fusion image showing the largest tumor area was generated for analysis. Registration accuracy between PET and DWI was assessed based on the area of maximum overlap and central point displacement of the tumor. EPI factor, echo time (TE), matching area, and displacement were compared between c-DWI and z-DWI by paired t-test. Agreement of apparent diffusion coefficient (ADC) acquired by the two sequences were also assessed with linear regression s and Bland-Altman plot analysis.
ResultsThirty-two lesions were detected on both PET and DWI (mean size 536.3471.8mm(2)). At least one lesion was found in all subjects. In all cases, EPI factor was smaller with z-DWI than c-DWI (43.1 +/- 15.6 vs. 62.0 +/- 10.0, P < 0.0001), and TE was also shorter for z-DWI (53.6 +/- 3.6 msec vs. 65.2 +/- 3.6 msec, P < 0.0001). Registration accuracy was better with z-DWI in 30 of 32 lesions (93.8%), and both average matching area and central point displacement were significantly improved (79.8 +/- 18.1% vs. 61.8 +/- 22.9%, P < 0.0001 and 3.92 +/- 2.69mm vs. 7.51 +/- 4.07mm, P < 0.0001). ADC values calculated with c-DWI and z-DWI showed good agreement.
ConclusionZoomed DWI reduces image distortion and provides better registration accuracy with PET images. J. Magn. Reson. Imaging 2016;43:853-858.
32. Ken Sakaie, Masaya Takahashi, Gina Remington, Xiaofeng Wang, Amy Conger, Darrel Conger, Ivan Dimitrov, Stephen Jones, Ashley Frohman, Teresa Frohman, Koji Sagiyama, Osamu Togao, Robert J. Fox, Elliot Frohman, Correlating Function and Imaging Measures of the Medial Longitudinal Fasciculus, PLOS ONE, 10.1371/journal.pone.0147863, 11, 1, e0147863, 2016.01, Objective
To test the validity of diffusion tensor imaging (DTI) measures of tissue injury by examining such measures in a white matter structure with well-defined function, the medial longitudinal fasciculus (MLF). Injury to the MLF underlies internuclear ophthalmoparesis (INO).
40 MS patients with chronic INO and 15 healthy controls were examined under an IRB-approved protocol. Tissue integrity of the MLF was characterized by DTI parameters: longitudinal diffusivity (LD), transverse diffusivity (TD), mean diffusivity (MD) and fractional anisotropy (FA). Severity of INO was quantified by infrared oculography to measure versional disconjugacy index (VDI).
LD was significantly lower in patients than in controls in the medulla-pons region of the MLF (p < 0.03). FA was also lower in patients in the same region (p < 0.0004). LD of the medullapons region correlated with VDI (R = -0.28, p < 0.05) as did FA in the midbrain section (R = 0.31, p < 0.02).
This study demonstrates that DTI measures of brain tissue injury can detect injury to a functionally relevant white matter pathway, and that such measures correlate with clinically accepted evaluation indices for INO. The results validate DTI as a useful imaging measure of tissue integrity..
33. Osamu Togao, Akio Hiwatashi, Jochen Keupp, Koji Yamashita, Kazufumi Kikuchi, Takashi Yoshiura, Yuriko Suzuki, Marijn J. Kruiskamp, Koji Sagiyama, Masaya Takahashi, Hiroshi Honda, Scan-rescan reproducibility of parallel transmission based amide proton transfer imaging of brain tumors, JOURNAL OF MAGNETIC RESONANCE IMAGING, 10.1002/jmri.24895, 42, 5, 1346-1353, 2015.11, PurposeTo evaluate the reproducibility of amide proton transfer (APT) imaging of brain tumors using a parallel transmission-based technique.
Materials and MethodsThirteen patients with brain tumors (four low-grade gliomas, three glioblastoma multiforme, five meningiomas, and one malignant lymphoma) were included in the study. APT imaging was conducted at 3T using a 2-channel parallel transmission scheme with a saturation time of 2 seconds and B-1 amplitude of 2 T. A 2D fast spin-echo sequence with driven-equilibrium refocusing was used for imaging. Z-spectra were obtained at 25 frequency offsets from -6 to +6 ppm (step 0.5 ppm). A point-by-point B-0 correction was performed with a B-0 map. A scan-rescan reproducibility test was performed in two sessions on separate days for each patient. The interval between the two sessions was 4.83.5 days. Regions-of-interest (ROIs) were placed to include the whole tumor for each case. A mean and 90-percentile value of APT signal for the whole tumor histogram was calculated for each session. The between-session and within-session reproducibility was evaluated using linear regression analysis, intraclass correlation coefficient (ICC), and a Bland-Altman plot.
ResultsThe mean and 90-percentile values of the APT signal for whole tumor ROI showed excellent agreements between the two sessions, with R-2 of 0.91 and 0.96 in the linear regression analysis and ICC of 0.95 and 0.97, respectively.
ConclusionParallel transmission-based APT imaging of brain tumors showed good reproducibility. J. Magn. Reson. Imaging 2015;42:1346-1353..
34. Amit Kumar, Shanrong Zhang, Guiyang Hao, Gedaa Hassan, Saleh Ramezani, Koji Sagiyama, Su-Tang Lo, Masaya Takahashi, A. Dean Sherry, Orhan K. Oez, Zoltan Kovacs, Xiankai Sun, Molecular Platform for Design and Synthesis of Targeted Dual Modality Imaging Probes, BIOCONJUGATE CHEMISTRY, 10.1021/acs.bioconjchem.5600028, 26, 3, 549-558, 2015.03, We report a versatile dendritic structure based platform for construction of targeted dual-modality imaging probes. The platform contains multiple copies of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) branching out from a 1,4,7-triazacyclononane-N,N',N"-triacetic acid (NOTA) core. The specific coordination chemistries of the NOTA and DOTA moieties offer specific loading of Ga-68/67(3+) and Gd3+, respectively, into a common molecular scaffold. The platform also contains three amino groups which can potentiate targeted dual-modality imaging of PET/MRI or SPECT/MRI (PET: positron emission tomography; SPECT: single photon emission computed tomography; MRI: magnetic resonance imaging) when further functionalized by targeting vectors of interest. To validate this design concept, a bimetallic complex was synthesized with six peripheral Gd-DOTA units and one Ga-NOTA core at the center, whose ion T1 relaxivity per gadolinium atom was measured to be 15.99 mM(-1) s(-1) at 20 MHz. Further, the bimetallic agent demonstrated its anticipated in vivo stability, tissue distribution, and pharmacokinetic profile when labeled with Ga-67. When conjugated with a model targeting peptide sequence, the trivalent construct was able to visualize tumors in a mouse xenograft model by both PET and MRI via a single dose injection..
35. Osamu Togao, Takashi Yoshiura, Jochen Keupp, Akio Hiwatashi, Koji Yamashita, Kazufumi Kikuchi, Yuriko Suzuki, Satoshi O. Suzuki, Toru Iwaki, Nobuhiro Hata, Masahiro Mizoguchi, Koji Yoshimoto, Koji Sagiyama, Masaya Takahashi, Hiroshi Honda, Amide proton transfer imaging of adult diffuse gliomas: correlation with histopathological grades, NEURO-ONCOLOGY, 10.1093/neuonc/not158, 16, 3, 441-448, 2014.03, Background. Amide proton transfer (APT) imaging is a novel molecular MRI technique to detect endogenous mobile proteins and peptides through chemical exchange saturation transfer. We prospectively assessed the usefulness of APT imaging in predicting the histological grade of adult diffuse gliomas.
Methods. Thirty-six consecutive patients with histopathologically proven diffuse glioma (48.1 +/- 14.7 y old, 16 males and 20 females) were included in the study. APT MRI was conducted on a 3T clinical scanner and was obtained with 2 s saturation at 25 saturation frequency offsets omega = -6 to + 6 ppm (step 0.5 ppm). delta B-0 maps were acquired separately for a point-by-point delta B-0 correction. APT signal intensity (SI) was defined as magnetization transfer asymmetry at 3.5 ppm: magnetization transfer ratio (MTR)(asym) = (S[-3.5 ppm] -S[+ 3.5 ppm])/S-0. Regions of interest were carefully placed by 2 neuroradiologists in solid parts within brain tumors. The APT SI was compared with World Health Organization grade, Ki-67 labeling index (LI), and cell density.
Results. The mean APT SI values were 2.1 +/- 0.4% in grade II gliomas (n = 8), 3.2 +/- 0.9% in grade III gliomas (n = 10), and 4.1 +/- 1.0% in grade IV gliomas (n = 18). Significant differences in APT intensity were observed between grades II and III (P < .05) and grades III and IV (P < .05), as well as between grades II and IV (P < .001). There were positive correlations between APT SI and Ki-67 LI (P = .01, R = 0.43) and between APT SI and cell density (P < .05, R = 0.38). The gliomas with microscopic necrosis showed higher APT SI than those without necrosis (P < .001).
Conclusions. APT imaging can predict the histopathological grades of adult diffuse gliomas..
36. Koji Sagiyama, Tomoyuki Mashimo, Osamu Togao, Vamsidhara Vemireddy, Kimmo J. Hatanpaa, Elizabeth A. Maher, Bruce E. Mickey, Edward Pan, A. Dean Sherry, Robert M. Bachoo, Masaya Takahashi, In vivo chemical exchange saturation transfer imaging allows early detection of a therapeutic response in glioblastoma, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 10.1073/pnas.1323855111, 111, 12, 4542-4547, 2014.03, Glioblastoma multiforme (GBM), which account for more than 50% of all gliomas, is among the deadliest of all human cancers. Given the dismal prognosis of GBM, it would be advantageous to identify early biomarkers of a response to therapy to avoid continuing ineffective treatments and to initiate other therapeutic strategies. The present in vivo longitudinal study in an orthotopic mouse model demonstrates quantitative assessment of early treatment response during short-term chemotherapy with temozolomide (TMZ) by amide proton transfer (APT) imaging. In a GBM line, only one course of TMZ (3 d exposure and 4 d rest) at a dose of 80 mg/kg resulted in substantial reduction in APT signal compared with untreated control animals, in which the APT signal continued to increase. Although there were no detectable differences in tumor volume, cell density, or apoptosis rate between groups, levels of Ki67 (index of cell proliferation) were substantially reduced in treated tumors. In another TMZ-resistant GBM line, the APT signal and levels of Ki67 increased despite the same course of TMZ treatment. As metabolite changes are known to occur early in the time course of chemotherapy and precede morphologic changes, these results suggest that the APT signal in glioma may be a useful functional biomarker of treatment response or degree of tumor progression. Thus, APT imaging may serve as a sensitive biomarker of early treatment response and could potentially replace invasive biopsies to provide a definitive diagnosis. This would have a major impact on the clinical management of patients with glioma..
37. Ken Sakaie, Masaya Takahashi, Koji Sagiyama, Ivan Dimitrov, Teresa Frohman, Gina Remington, Elliot Frohman, Robert J. Fox, Clinical/scientific notes, Neurology, 10.1212/WNL.0000000000000016, 82, 2, 182-183, 2014.01.
38. Osamu Togao, Chase W. Kessinger, Gang Huang, Todd C. Soesbe, Koji Sagiyama, Ivan Dimitrov, A. Dean Sherry, Jinming Gao, Masaya Takahashi, Characterization of Lung Cancer by Amide Proton Transfer (APT) Imaging: An In-Vivo Study in an Orthotopic Mouse Model, PLOS ONE, 10.1371/journal.pone.0077019, 8, 10, e77019, 2013.10, Amide proton transfer (APT) imaging is one of the chemical exchange saturation transfer (CEST) imaging methods which images the exchange between protons of free tissue water and the amide groups (-NH) of endogenous mobile proteins and peptides. Previous work suggested the ability of APT imaging for characterization of the tumoral grade in the brain tumor. In this study, we tested the feasibility of in-vivo APT imaging of lung tumor and investigated whether the method could differentiate the tumoral types on orthotopic tumor xenografts from two malignant lung cancer cell lines. The results revealed that APT imaging is feasible to quantify lung tumors in the moving lung. The measured APT effect was higher in the tumor which exhibited more active proliferation than the other. The present study demonstrates that APT imaging has the potential to provide a characterization test to differentiate types or grade of lung cancer noninvasively, which may eventually reduce the need invasive needle biopsy or resection for lung cancer..
39. Xiaonan Huang, Gang Huang, Shanrong Zhang, Koji Sagiyama, Osamu Togao, Xinpeng Ma, Yiguang Wang, Yang Li, Todd C. Soesbe, Baran D. Sumer, Masaya Takahashi, A. Dean Sherry, Jinming Gao, Multi-Chromatic pH-Activatable F-19-MRI Nanoprobes with Binary ON/OFF pH Transitions and Chemical-Shift Barcodes, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 10.1002/anie.201301135, 52, 31, 8074-8078, 2013.07.
40. Hironori Kamano, Takashi Yoshiura, Akio Hiwatashi, Koji Yamashita, Yukihisa Takayama, Eiki Nagao, Koji Sagiyama, Ivan Zimine, Hiroshi Honda, Accelerated territorial arterial spin labeling based on shared rotating control acquisition: an observer study for validation, NEURORADIOLOGY, 10.1007/s00234-011-0919-2, 54, 1, 65-71, 2012.01, Introduction Shared rotating control acquisition can shorten the imaging time of territorial arterial spin labeling (tASL) by 33% compared with the normal control acquisition scheme but potentially results in an inaccurate estimate of vascular territories due to imperfect magnetization transfer compensation. Our purpose was to validate the accuracy of the shared rotating control acquisition method in evaluation of vascular territories.
Methods Twenty-four patients underwent tASL at a 3.0-T MRI with the conventional normal control acquisition method. Composite vascular territory maps, in which the blood flows from the right and left internal carotid arteries and the posterior circulation were encoded in red-green-blue, were generated as a normal averaged control-label scheme and as a simulated shared rotating control scheme. Two observers independently reported the most dominant territorial flow in 26 brain regions corresponding to the arterial segments at three post-labeling time points. Inter-reader and inter-method agreements were analyzed using kappa statistics.
Results Overall inter-reader agreements were excellent for both the normal control and the shared rotating control methods (kappa = 0.98, respectively). Overall inter-method agreement was also excellent (kappa = 0.98), although relatively low agreement was noted in the bilateral posterior cerebral artery territories (kappa = 0.79 to 0.93).
Conclusion Our results suggested that tASL using shared rotating control acquisition can provide information on the vascular territories comparable to that obtained using the normal control acquisition while substantially shortening the imaging time..