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Masayuki Sasaki Last modified date:2019.04.17

Professor / Graduate School of Medical Sciences, Faculty of Medicine, Department of Health Sciences, Medical Quantum Science
Department of Health Sciences
Faculty of Medical Sciences


Graduate School
Undergraduate School
Other Organization
Administration Post
Director of the Research Center for Education in Health Care System


E-Mail
Phone
092-642-6746
Academic Degree
MD, PhD
Country of degree conferring institution (Overseas)
No
Field of Specialization
Radiology, Nuclear Medicine
Total Priod of education and research career in the foreign country
01years00months
Outline Activities
Research: Non-invasive in vivo molecular imaging of oncology using nuclear medicine technology,
maging of tumor metabolism and CNS function by positron emission tomography (PET)

Education: molecular imaging, nuclear medicine technology, Radiochemistry, History of Radiology
Research
Research Interests
  • Molecular imaging of the oncology using PET/CT and SPECT/CT
    keyword : PET/CT, SPECT/CT, molecular imaging
    1993.10.
  • Molecular imaging of the brain using PET/CT and SPECT/CT
    keyword : PET/CT, SPECT/CT, brain
    1993.10.
Academic Activities
Papers
1. Yoshiyuki Kitamura, Koichiro Abe, Akio Sakamoto, Shingo Baba, Takuro Isoda, Yasuhiro Maruoka, Yoshio Matsuo, Kubo Y, Hiroshi Nishimura, Masayuki Sasaki, Hiroshi Honda, Malignant triton tumor in the abdominal wall: a case report, Advances in Molecular Imaging (AMI) ., DOI: 10.4236/ami.2013.32002,, Advances in Molecular Imaging (AMI) . 2013; 3(2): 9-13. DOI: 10.4236/ami.2013.32002,, 2013.02, Advances in Molecular Imaging (AMI) . 2013; 3(2): 9-13. DOI: 10.4236/ami.2013.32002,.
2. Yasuhiro Maruoka, Koichiro Abe, Shingo Baba, Takuro Isoda, Yoshio Matsuo, Kubo Y, Ogawa S, Yano T, Masayuki Sasaki, Hiroshi Honda, A case of pulmonary choriocarcinoma metastasis with unusual FDG-PET and CT findings: correlation with pathology., Ann Nucl Med. , 10.1007/s12149-012-0644-x. , Ann Nucl Med. 2012 Dec;26(10):835-9. doi: 10.1007/s12149-012-0644-x. Epub 2012 Aug 15., 2012.12, Ann Nucl Med. 2012 Dec;26(10):835-9. doi: 10.1007/s12149-012-0644-x. Epub 2012 Aug 15..
3. Shinmura A, Koichiro Abe, Shingo Baba, Takuro Isoda, Yasuhiro Maruoka, Yasukawa F, Kiryu H, Masayuki Sasaki, Hiroshi Honda, Masutaka Furue, FDG PET/CT Findings in Acquired Perforating Dermatosis., Clin Nucl Med. , doi: 10.1097/PCR.0b013e3182675159., Clin Nucl Med. 2012 Oct;37(10):997-1000. doi: 10.1097/PCR.0b013e3182675159., 2012.10, Clin Nucl Med. 2012 Oct;37(10):997-1000. doi: 10.1097/PCR.0b013e3182675159..
4. Go Akamatsu, Katsuhiko Mitsumoto, Kaori Ishikawa, Takafumi Taniguchi, Nobuyoshi Oya, Shingo Baba, Koichiro Abe, Masayuki Sasaki, Benefits of point-spread-function and time-of-flight for PET/CT image quality in relation to the body mass index and injected dose., Clin Nucl Med., 10.1097/RLU.0b013e31828da3bd., 2013.06, Clin Nucl Med. 2013 Jun;38(6):407-12. doi: 10.1097/RLU.0b013e31828da3bd.  Epub 2013 Apr 18.

The PET image quality of overweight patients and patients who receive low injected doses deteriorates because of increases in statistical noise. The purpose of this study was to investigate the benefits of the point-spread-function (PSF) and time-of-flight (TOF) for PET/CT image quality in such patients. Methods: The PET images were reconstructed using the baseline ordered-subsets expectation-maximization algorithm (OSEM), OSEM+PSF, OSEM+TOF and OSEM+PSF+TOF. In the phantom study, we used a NEMA body phantom with different radioactivity concentrations, and analyzed image quality using the coefficient of variance in the background (CVphantom). In the clinical study, we retrospectively studied 39 patients who underwent clinical 18F-FDG PET/CT. The patients were classified into groups based on body mass index and injected dose. Image quality was evaluated using the CV in the liver (CVliver). Results: In the phantom study, PSF and TOF improved the CVphantom, especially in low-activity models. Among all of the reconstructions, the best CVphantom was obtained with OSEM+PSF+TOF. In the clinical study, the CVliver of the low-dose group with OSEM+PSF+TOF was comparable to that of the high-dose group with conventional OSEM. Conclusion: PSF and TOF improved PET/CT image quality for overweight patients who received a lower injected dose. Therefore, the use of PSF and TOF is suggested to maintain the image quality of such patients without extending scanning times. It is greatly beneficial to obtain sufficient image quality for larger patients, especially in delivery institutions where the injection dose cannot be easily increased..
5. Yasuhiro Maruoka, Koichiro Abe, Shingo Baba, Takuro Isoda, Hirofumi Sawamoto, Tanabe Y, Masayuki Sasaki, Hiroshi Honda, Incremental Diagnostic Value of SPECT/CT with 131I Scintigraphy after Radioiodine Therapy in Patients with Well-differentiated Thyroid Carcinoma., Radiology, 10.1148/radiol.12112108. , Radiology. 2012 Dec;265(3):902-9. doi: 10.1148/radiol.12112108. Epub 2012 Sep 25., 2012.12, Radiology. 2012 Dec;265(3):902-9. doi: 10.1148/radiol.12112108. Epub 2012 Sep 25..
6. Go Akamatsu, Kaori Ishikawa, Katsuhiko Mitsumoto, Takafumi Taniguchi, Nobuyoshi Oya, Shingo Baba, Koichiro Abe, Masayuki Sasaki, Improvement in PET/CT image quality with a combination of the point-spread-function and time-of-flight in relation to the reconstruction parameters., J Nucl Med, 10.2967/jnumed.112.103861., 53, 11, 1716-1722, 2012.11, J Nucl Med. 2012 Nov;53(11):1716-22. doi: 10.2967/jnumed.112.103861. Epub 2012 Sep 4.

The aim of this study was to investigate the effects of the point-spread-function (PSF) and time-of-flight (TOF) on improving 18F-FDG PET/CT images in relation to reconstruction parameters and noise equivalent counts (NEC). Methods: This study consisted of a phantom study and a retrospective analysis of 39 consecutive patients who underwent clinical 18F-FDG PET/CT. The NEMA IEC body phantom with a 10-mm-diameter sphere was filled with an 18F-FDG solution with a 4:1 radioactivity ratio compared with the background. The PET data were reconstructed with the baseline OSEM algorithm, with the OSEM+PSF model, with the OSEM+TOF model, and with the OSEM+PSF+TOF model. We evaluated the image quality by visual assessment, the signal-to-noise ratio of the 10-mm sphere (SNR10mm), the contrast of the 10-mm sphere, and the coefficient of variance (CV) in the phantom study, and then determined the optimal reconstruction parameters. We also examined the effects of PSF and TOF on the image quality of clinical images using the signal-to-noise ratio in the liver (SNRliver) in relation to the NEC in the liver (NECliver). Results: In the phantom study, the SNR10mm was the highest for the OSEM+PSF+TOF model, and the highest value was obtained at iteration 2 for algorithms with the TOF, and 3 for those without the TOF. In terms of a post-smoothing filter FWHM, the high SNR10mm was obtained with no filtering or was smaller than 2 mm for algorithms with PSF, and was 4–6 mm for those without PSF. The balance between the contrast recovery and noise is different for algorithms with either PSF and/or TOF. A combination of PSF and TOF improved the SNR10mm, contrast and CV, especially with a small-FWHM Gaussian filter. In the clinical study, the SNRliver of the low-NECliver group in the OSEM+PSF+TOF model was compared to that of high-NECliver group in the conventional OSEM. The PSF+TOF improved the SNRliver by about 24.9±9.81%. Conclusion: A combination of PSF and TOF clearly improves the image quality, while the optimization of the reconstruction parameters is necessary to obtain the best performance of PSF and/or TOF. Furthermore, this combination has the potential to provide good image quality with either lower activity or shorter acquisition time, thus improving the patient comfort and reducing the radiation burden..
7. Sasaki M, Sugio K, Kuwabara Y, Koga H, Nakagawa M, Chen T, Kaneko K, Hayashi K, Shioyama Y, Sakai S, Honda H, Alterations of tumor suppressor genes (Rb, p16, p27 and p53) and increased FDG uptake in lung cancer, Annals of Nuclear Medicine, 10.1007/BF02990021, 17, 3, 189-196, 17 (3): 189 - 196, 2003.05.
8. Sasaki M, Kuwabara Y, Koga H, Nakagawa M, Chen T, Kaneko K, Hayashi K, Nakamura K, Masuda K, Clinical impact of whole body FDG-PET on the staging and therapeutic decision making for malignant lymphoma, Annals of Nuclear Medicine, 10.1007/BF02988618, 16, 5, 337-345, 16 (5): 337 - 345, 2002.07.
9. Sasaki M, Fukumura T, Kuwabara Y, Yoshida T, Nakagawa M, Ichiya Y, Masuda K, Biodistribution and breast tumor uptake of 16α-[18F]-fluoro-17β-estradiol in rat, Ann Nucl Med, 10.1007/BF02988592, 14, 2, 127-130, Vol.14,No.2,pp.127 - 130, 2000.02.
10. Sasaki M, Kuwabara, Y, Ichiya, Y, Yoshida, T, Nakagawa, M, Soeda, H, Sugio, K, Maehara, Y, Masuda, Prediction of the chemosensitivity of lung cancer by 99mTc-hexakis-2-methoxyisobutyl isonitrile SPECT, J Nucl Med, 40, 11, 1778-1783, Vol.40,No.11,pp.1778 - 1783, 1999.11.
11. Sasaki M, Ichiya Y, Kuwabara Y, Yoshida T, Fukumura T, Masuda K., Benzodiazepine receptors in chronic cerebrovascular disease: comparison with blood flow and metabolism., J Nucl Med, 38, 11, 1693-1698, 1997.11.
12. Sasaki M, Kuwabara Y, Yoshida T, Nakagawa M, Fukumura T, Mihara F, Morioka T, Fukui M, Masuda K, A comparative study of thallium-201 SPET, carbon-11 methionine PET and fluorine-18 fluorodeoxyglucose PET for the differentiation of astrocytic tumors, Eur J Nucl Med, 10.1007/s002590050294, 25, 9, 1261-1269, Vol.25,No.9,pp.1262 - 1269, 1998.09.
13. Sasaki M, Ichiya Y, Kuwabara Y, Akashi Y, Yoshida T, Fukumura T, Murayama S, Ishida T, Sugio K, Masuda K., The usefulness of FDG positron emission tomography for the detection of mediastinal lymph node metastases in patients with non-small cell lung cancer: a comparative study with X-ray computed tomography., Eur J Nucl Med, 10.1007/BF00843701, 23, 7, 741-747, 1996.07.
14. Sasaki M, Sugio K, Sasazuki T., K-ras activation in colorectal tumors from patients with familial polyposis coli., Cancer, 10.1002/1097-0142(19900601)65:11<2576::AID-CNCR2820651130>3.0.CO;2-4, 65, 11, 2576-2579, 1990.06.
15. Okamoto M, Sasaki M, Sugio K, Sato C, Iwama T, Ikeuchi T, Tonomura A, Sasazuki T, Miyaki M., Loss of constitutional heterozygosity in colon carcinoma from patients with familial polyposis coli. , Nature (Lond.), 10.1038/331273a0, 331, 6153, 273-277, 1988.01.
16. Sasaki M, Okamoto M, Sato C, Sugio K, Soejima J, Iwama T, Ikeuchi T, Tonomura A, Miyaki M, Sasazuki T:, Loss of constitutional heterozygosity in colorectal tumors from patients with familial polyposis coli and those with non-polyposis colorectal carcinoma. , Cancer Res, 49, 16, 4402-4406, 1989.08.
Membership in Academic Society
  • Japanese Society of Nuclear Medicine
  • Japan Radiological Society
  • Japanese Society for Therapeutic Radiology and Oncology
  • Society of Nuclear Medicine
  • The Japanese Cancer Association
  • The Japan Lung Cancer Society
  • Japan Radioisotope Association
Educational
Educational Activities
Department of Health Sciences, School of Medicine,
Molecular imaging, Nuclear medicine technology, Radiochemistry, History of Radiology