2018 Volume 30 Issue 1 Pages 1-10
Objective: The aim of this study was to show that 2-min inhalation xenon CT (Xe-CT) can create cerebral blood flow (CBF) images comparable with those by conventional 4-min inhalation Xe-CT. Methods: 2-min inhalation Xe-CT was conducted on consecutive 8 patients aged 75 or older who visited the department of neuropsychiatry. Basal ganglia and lateral ventricle levels were selected for Xe-CT. 30% xenon was inhaled for 2 minutes, then air was inhaled for 3 minutes (2-min wash-in/3-min washout protocol). Contiguous 20 and 18 circular regions of interest (ROIs) were placed around the cortex at the basal ganglia and lateral ventricle levels respectively, and CBF was calculated for each ROI. Utilizing AD patients’ CBF range (AD range) and healthy volunteers’ CBF range (normal range) for each ROI obtained by the 4-min wash-in/4-min washout protocol, the ROI distribution (number of ROIs in AD ranges minus number of ROIs in normal ranges) was obtained. Results: Using the optimal cutoff value of the ROI distribution obtained by the 4-min wash-in/4-min washout protocol, one patient diagnosed as normal was identified as “normal”, and 4 of the 5 patients diagnosed as AD were identified as “AD”. Since the conventional optimal cutoff value was effective, CBF values by the 2-min wash-in/3-min washout protocol were close to those by the 4-min wash-in/4-min washout protocol. Conclusions: We demonstrated that CBF images by 2-min inhalation Xe-CT would be close to those by conventional 4-min inhalation Xe-CT and could be effectively used for clinical evaluation.
