Utility of Diffusion-weighted MR Imaging in Acute Stage of Small Cerebral Infarction

PURPOSE: To demonstrate the usefulness of diffusion-weighted MR imaging(DWI) in patients with small acuteinfarction by comparing it with fast spin-echo T2-weighted MR imaging(FSE T2WI). MATERIAL AND METHOD: Weretrospectively analyzed the results of FSE T2WI in 26 consecutive patients who on DWI showed small discretehyperintensities of less than 1.5cm and whose final clinical diagnosis, within one week of clinical attack, wasacute inforction. Lacunar infarcts accounted for 24 cases and 2 small cortical infarcts for two. The onset ofsymptoms occurred within 12 hours (hyperacute stage) in two patients, within 24 hours in seven, within 3 days innine, and within one week in eight. Infarcts as seen on FSE T2WI were categorized as follows : (-) for cases ofimpossible localization with non-visualization ; (+/-) for cases of equivocal localization with faint visualizationand/or poor differentiation from combined chronic infarcts and chronic ischemic changes, or from subarachnoid CSFin cases of cortical infarction ; and (+) for cases of adequate localization with clear visualization andmoderately good differentiation from the associated brain changes, or from subarachnoid CSF in cases of corticalinfarction. These infarcts were analyzed according to the time of onset of symptoms. RESULT: For the localizationof small acute infarctions, DWI was markedly superior to the category(-), moderately superior to the category(+/-).With regard to the onset of symptoms, DWI was markedly or moderately superior to FSE T2WI in 2/2 (100%) ofhyperacute stage diagnosed within 12 hour of clinical attack, in 4/7(57%) diagnosed within 24 hours, in 5/9 (56%)diagnosed within 3 days, and in 1/8 (13%) diagnosed within 1 week(p<0.05). In 12/26 cases(46%), small acuteinfarcts were localized by DWI better than by FSE T2WI. CONCLUSION: Because the signal was unchanged or itsintensity was poor, small infarcts at the acute stage were frequently difficult to localize by FSE T2WI. Inaddition, differentiation of these from combined chronic infarcts and chronic ischemic change was poor. DWI canlocalize small acute infarcts even when the results of FSE T2WI are negative or inconclusive.

Non-obstructive Biliary Dilatation After Gastrectomy for Gastric Carcinoma

PURPOSE: To evaluate the incidence,. degree, and clinical significance of non-obstructive intrahepatic bile duct di'latation encountered on follow up CT after gastrectomy for gastric carcinoma. MATERIALS AND METHODS: We retrospectively analyzed follow-up abdominal CT of 65 patients who had undergone gastrectomy with truncal vagotomy and subtotal gastrectomy for gastric carcinoma. We classified those patients who showed intrahepatic duct dilatation into non-obstructive or obstructive groups depending on the presence or absence of the lesions obstructing the duct. We also evaluated the incidence, degree and pattern, and appearance time of non-obstructive type of duct dilatation. RESULTS: Non-obstructive and obstructive biliary dilatations were present in 8 cases(12.3%) and 9 cases(13. 8%), respectively. The degree of non-obstructive group was mild in 6 cases(75%) and moderate in 2 cases (25%) who had taken cholecystectomy during the follow up period, and patterns were proportional dilatation of the central and peripheral intrahepatic ducts. It appeared on follow up CT obtained 6 to 12 months after operation in 7 cases and 3.5 months in one case. No statistical significance was noted between the type of surgery and the incidence of non-obstructive dilatation(p>0.05). CONCLUSION: Mild dilatation of the central intrahepatic ducts without evidence of mechanical biliary obstruction can be seen on follow-up CT obtained more than 6 months after gastrectomy for gastric carcinoma, and the incidence is about 12%. We think that this finding is non-obstructive and clinical evaluation is unnecessary.