title: Extraction of arterial input function for measurement of brain perfusion index with 99mTc compounds using fuzzy clustering.
abstract: Cerebral blood flow (CBF) can be quantified non-invasively using the brain perfusion index (BPI) determined from radionuclide angiographic data generated with 99mTc-hexamethylpropylene amine oxime (99mTc-HMPAO). When measuring the BPI, manual drawing of regions of interest (ROIs) (manual ROI method) for the extraction of the arterial input function (AIF) can lead to serious individual differences. The purpose of this study was to apply the fuzzy c-means (FCM) clustering method to determine AIF, and to investigate its usefulness in comparison with the manual ROI method. Radionuclide angiography was performed using a bolus injection of about 555 MBq of 99mTc-HMPAO, followed by sequential imaging (1 sec/frame x 120 s) using a solid-state gamma camera, and the BPI values were calculated using spectral analysis. To investigate the dependence of BPI on the ROI size, we drew five ROIs with different sizes over the aortic arch, and calculated the BPI using the manual ROI method [BPI(manual)] and the FCM clustering method [BPI(FCM)]. Furthermore, we asked 10 individuals to draw ROIs to investigate the inter-operator variability of the two methods. The mean and standard deviation (SD) of BPI(manual) increased with increasing ROI size, whereas the mean of BPI(FCM) was almost constant regardless of the ROI size; the SD of BPI(FCM) was smaller than that of BPI(manual). The inter-operator variability of the FCM clustering method was smaller than that of the manual ROI method. These results suggest that the FCM clustering method appears to be useful for the measurement of BPI, because it allows a reliable and objective determination of AIF.
authors.affiliation: Department of Medical Physics and Engineering, Division of Medical Technology and Science, Course of Health Science, Graduate School of Medicine, Osaka University, Osaka, Japan. murase@sahs.med.osaka-u.ac.jp
authors.forename: Kenya
authors.initials: K
authors.lastname: Murase
authors.forename: Makoto
authors.initials: M
authors.lastname: Nagayoshi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Uenishi
authors.forename: Minoru
authors.initials: M
authors.lastname: Kawamata
authors.forename: Youichi
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Masashi
authors.initials: M
authors.lastname: Takasawa
authors.forename: Naohiko
authors.initials: N
authors.lastname: Oku
authors.forename: Jun
authors.initials: J
authors.lastname: Hatazawa
mesh_terms: D000368:Aged; D000465:Algorithms; D001158:Arteries / Q000000981:diagnostic imaging; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging*; D001927:Brain Diseases / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation; D016000:Cluster Analysis; D005260:Female; D017143:Fuzzy Logic; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011865:Radioisotope Dilution Technique; D011875:Radionuclide Angiography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019690:Technetium Tc 99m Exametazime
chemical_list: D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime