IMPROVED CT DIAGNOSIS OF ACUTE MIDDLE CEREBRAL-ARTERY TERRITORY INFARCTS WITH DENSITY-DIFFERENCE ANALYSIS

A new postprocessing method is described for CT detection of acute mid dle cerebral artery (MCA) territory infarcts by histograph analysis of density values. The density values in each CT slice were histographic ally recorded for each hemisphere. A density-difference diagram was ca lculated by digital subtraction of the histogram of the left hemispher e from that of the right. Pixels within the highest density-difference ranges were highlighted. To investigate the value of this method CT s tudies of 30 patients with acute MCA territory infarcts and of 15 norm al CT studies were analysed by two radiologists and neurosurgeons. CT images with and without postprocessing were assessed for the presence, site and size of infarcts. Follow-up CT was used as control. With den sity-difference analysis (DDA) the detection rate for infarcts increas ed significantly (96 % compared to 61 %). In no case was a correct dia gnosis made on the unpostprocessed images falsely revised with DDA. Al l normal CT studies were detected correctly using DDA.