Usefulness of the Helical CT in the Diagnosis of Periampullary Malignant Tumors

PURPOSE: To evaluate the usefulness of the helical CT in the differentiation of periampullary malignanttumors. MATERIALS AND METHODS: Fifty-five periampullary carcinoma patients (pancreatic head carcinoma (n=18);distal CBD carcinoma (n=17) ; carcinoma of the ampulla of Vater(n=16) ; periampullary duodenal cancers,(n=4), alldiagnosed by histopathologic study] underwent helical CT with 5mm scan thickness and 5mm/sec table speed. Afterscanning, retrospective reconstruction was performed at 2mm intervals, followed by multiplanar reformation. Inboth retrospective reconstructed axial and multiplanar reformation images, the authors analyzed the detection rateand size of the mass, and associated findings including invasion of peripancreatic fat, dilatation of CBD and itsnarrowing pattern, dilatation of the pancreatic duct and its degree of dilatation, wall thickening of CBD,extension of dilated bile duct into the ampulla, and of protruding mass into the duodenal lumen, and lymph nodemetastasis all according to the origin sites of tumors. Differential points were thus determined. RESULTS: Thedetection rate of the masses was 96% (53/55). Their size was 1-5cm, with a mean size of 2.4 +/-0.5cm in carcinomaof of ampulla of Vater and 3.5 +/-1.0cm in pancreatic head carcinoma. Invasion of peripancreatic fat was mostcommonly observed in pancreatic head carcinoma (100%, 18/18) (P >0 . 0 5 ), dilatation of CBD was observed in allcases except one of periampullary duodenal cancer (98%, 54/55), and abrupt termination of dilated bile duct wasnoted in all cases except one of the pancreatic head carcinoma (98%, 53/54). Dilatation of pancreatic duct wascommonly observed in pancreatic head carcinoma (94%, 17/18) and carcinoma of the ampulla of Vater (75%, 12/16).Its degree of dilatation was mostly moderate in pancreatic head carcinoma (56%, 10/18) and mostly mild incarcinoma of the ampulla of Vater (63%, 10/16) ( P >0.05). Wall thickening of the distal CBD was most commonlyobserved in distal CBD carcinoma (76%, 13/17). Extension of dilated bile duct into the ampulla was commonlyobserved in the carcinoma of the ampulla of Vater (81%, 13/16) and periampullary duodenal cancer (75%, 3/4) (P>0.05). A mass protruding into the duodenal lumen was commonly observed in periampullary duodenal cancer (100%,4/4) and carcinoma of the ampulla of Vater (94%, 15/16) (P >0.05). Lymph node meatastasis was observed inpancreatic head carcinoma (17%, 3/18) and distal CBD carcinoma (6%, 1/17). CONCLUSION: Because of improvement inthe rate at which the mass is detected, and a clear demonstration of associated findings, helical CT is useful inthe differentiation of periampullary carcinomas.

Dysphagia Following Stroke: Evaluation with Digital Radiography

PURPOSE: To evaluate the usefulness of digital radiography in the assessment of dysphagia following stroke. MATERIALS AND METHODS: Eighteen stroke patients (8 men, 10 women) referred for dysphagia and ten controls without known pharyngeal swallowing difficulty underwent digital radiography using a 1:1 mixture of barium and water. We evaluated oropharyngeal transit time and the location and severity of dysphagia; transit time was defined as the time from the first movement of the bolus to the return of the epiglottis to its original position. We sought to observe specific patterns of oropharyngeal dysfunction; dysphagia was classified as mild, moderate, or severe. RESULTS: In the control group, oropharyngeal transit time was 1.25sec (1.0-1.5sec), and for dysphagia patients, this was 4.32sec (1.75-6.5sec). Eleven patients (61%) had oral dysfunction, and 12 (67%), pharyngeal dysfunction; eight (44%) showed both oral and pharyngeal dysfunction. Mild swallowing difficulties occurred in six patients (33%), moderate dysfunction in six (33%), and severe dysfunction in three (17%). CONCLUSION: The dynamic image of the pharynx, as seen on a digital radiograph, may be diagnostically useful for defining the location and severity of dysphagia; in order to make feeding recommendations, this information is essential.

Usefulness of MR Urography in the Diagnosis of Hydroureteronephrosis

PURPOSE: To evaluate the clinical usefulness of the MR urography (MRU) in the diagnosis of hydroureteronephrosis. MATERIALS AND METHODS: Twenty-five patients with hydronephrosis (26 cases) underwent MR urography, using a 1.5T MR scanner (Signa Horizon, GE Medical Systems, Milwaukee, U.S.A). The causes of hydronephrosis included benign ureteral stricture (12), ureteral stones (8) and malignant strictures (6), and were confirmed by operation, biopsy, conventional urography or clinical follow up. For MRU, a fat suppressed, respiratory-triggered, heavily T2-weighted fast spin echo (FSE) pulse sequence was used, and the 3-dimensional MR images were subsequently processed by a maximum-intensity-projection algorithm. We evaluated the success rate of MRU and its accuracy in determining the level and cause of obstruction, and compared the degree of hydroureteronephrosis seen on MRU with that seen on conventional urography. RESULTS: In all cases, a urogram was successfully obtained. In determining the degree of hydroureteronephrosis and the level of obstruction (in the upper ureter in 11 cases, in the mid-ureter in four, and in the lower ureter in 11), MRU findings matched those of conventional urography. In 24/26 cases (92%), MRU accurately determined the cause of urinary tract obstruction ; the two exceptions were in cases involving ureteral stones. CONCLUSION: MRU is a promising, noninvasive diagnostic method for evaluating hydroureteronephrosis, especially in children, pregnant women and patients with an allergic reaction to iodinated contrast material.

Experimental Bacterial Meningitis in Rabbit : Evaluation with CT and MRI

PURPOSE: The purpose of this study was to evaluate the usefulness of computed tomography(CT) and magnetic resonance imaging(MRI) in experimental bacterial meningitis. MATERIALS AND METHODS: CT and MR images of experimental bacterial meningitis were obtained after inoculation of 1ml suspension of 106/ml Staphylococcusaureus directly into the supratentorial arachnoid space of 18 New Zealand white rabbits. Each animal was studied with both Pre-enhanced and post-enhanced CT and MRI at 12, 24, 48 hours and 1 week. Cerebrospinal fluid of all of18 rabbits were sampled and cultured for bacterial growth. RESULTS: All of 18 rabbits had the clinical symptoms such as neck stiffness and anorexia within 24 hours after the inoculation. Cerebrospinal fluid cultures werepositive for Staphylococcus sureus growth. Gd-enhanced MRI exhibited diffuse enhancement along the thickened supratentorial meninges earlier than CT. in Gd-enhanced MRI, the mean contrast enhancement ratio(CER) at supratentorial meninges increased to 1.93 at 12 hours and 2.99 at 24 hours from 1.06 at 0 hour. Histologic evaluation demonstrated inflammatory cell infiltration into the meninges. MRI also identified the complications of mening it is such as ependymitis and hydrocephalus more effectively than CT. CONCLUSION: These results indicatedthat Gd-enhanced MRI detected earlier the abnormal findings of bacterial meningitis and evaluated more effectively the complications of mening it is compared with CT. MRI was more useful than CT in evaluation of the bacterial meningitis.