Dynamic study of the Pancreas with Spiral CT: Comparison of Amount of The Contrast Medium

PURPOSE: To determine the hemodynamics of the pancreas by investigating the enhancement patterns of pancreaticparenchyma, as seen on spiral CT, after the administration of various amounts of contrast medium, and to determineoptimal scan time by knowing the peak time of normal pancreatic parenchyma. MATERIALS AND METHODS: Between January1995 and April 1997 55 cases of normal abdominal CT with dynamic enhancement study on pancreas, the subject were38 cases(28 persons) with good image, aged 21-65 years, men were twenty-one and women were seven. Non-ioniccontrast medium, 30ml(n=15), 60ml(n=9), 990ml(n=7), and 120ml(n=7) were injected at a rate of 3ml/sec. From 20sec. after the start of injection, 15 images were obtained at 3-sec intervals. Before and after injection, R.O.I.was applied to each image, and for the aorta and pancreatic parenchyma, Hounsfield units(H.U.) were measured; timeof enhancement and maximal H.U. were also measured. RESULTS: After 30, 60, 90, and 120ml of contrast mediuminjection, mean maximal H.U. of pancreatic parenchyma was 36+/-7, 54+/-6, 68V13, and 92+/-8, respectively; mean valueat peak parenchymal enhancement of the pancreas was 27+/-3, 32+/-3, 42+/-3, and 52+/-3, respectively. Time intervalsof maximal enhancement of aorta and pancreatic parenchyma could not be obtained in 30ml injection, but 5,4+/-2.5,4.2+/-1.6, and 6.0+/-2.1sec in 60, 90, and 120ml injection, respectively. CONCLUSION: Maximal H.U. of parenchymalenhancement of the pancreas is directly proportional to the amount of injected contrast medium and the peak timeof parenchymal enhancement was 12sec after the injection of contrast material. Time interval of maximalenhancement of aorta and pancreatic parenchyma was 5.2+/-2.1sec.

Comparison of Enhancement Pattern of Nodular and Massive Hepatocellular Carcinoma with and without Portal VeinThrombosis in Three-Phase Spiral CT

PURPOSE: To evaluate the enhancement patterns of nodular and massive hepatocellular carcinoma (HCC), with or without portal vein thrombosis, on three-phase spiral CT. MATERIALS AND METHODS: Contrast enhancement patterns in 61 patients with HCC were retrospectively analysed. Three-phase spiral CT images of the hepatic arterial dominant phase, portal dominant phase, and delayed phase were obtained 30, 60-70, and 360 seconds after the injection of contrast material was initiated. Tumors were divided into grossly nodular and massive type and enhancement patterns of HCC, with and without portal vein thrombosis, were compared. These patterns were divided into three groups, as follows: High/High/Low; High/Low/Low; Low/Low/Low. HCC with portal vein thrombosis was found in 21 of 61 cases ; this carcinoma without portal vein thrombosis was found in 40 cases. The nodular type accounted for 39 cases, and the massive type for 22. RESULTS: In 21 cases of HCC with portal vein thrombosis, the most common enhancement pattern was L/L/L, and was seen in 13 cases (62%); H/L/L was seen in eight (38%), but H/H/L was not seen. In 40 cases of HCC without portal vein thrombosis, the most common enhancement pattern was H/L/L, seen in 25 cases (63%) ; this was followed by L/L/L (11 cases ; 27%), and H/H/L (4 cases ; 10%). In the arterial dominant phase, among cases of HCC with portal vein thrombosis, low attenuation was more common (13/21) than high (8/21);among cases of HCC without portal vein thrombosis, high attenuation was more common (29/40) than low (11/40). Among 39 nodular-type cases, HCC with portal vein thrombosis was found in six (H/H/L and L/L/L: three each), and HCCwithout portal vein thrombosis was seen in 33 (H/L/L: 22; L/L/L: 7; H/H/L; 4). Among 22 cases of the massive type, HCC with portal vein thrombosis accounted for 15 (L/L/L: 10, H/L/L: 5), and seven cases without portal vein thrombosis were seen (L/L/L: 4 ; H/L/L : 3). CONCLUSION: On Three-phase spiral CT, HCC showed different enhancing patterns according tumor type and the presence of portal vein thrombosis.

Morphological Variation of the Kidney Secondary to Junctional Parenchyma on Ultrasound

PURPOSE: To evaluate the prevalance of morphological variation of the kidney secondary to junctional parenchyma, as well as to analyze the ultrasonographic features of junctional parenchyma. MATERIALS AND METHODS: Two hundred and eighty two kidneys of 141 patient without clinical or radiologic evidence of renal disease were prospectively analysed using ultrasound. In all patients, ultrasonograms were obtained in sagittal, coronal and transaxial planes. The kidney was considered to have morphological variation if the ulrasonogram demonstrated junctional parenchymal defect or line ; those showing such variation were classified as one of three types :continuous, discontinuous, or junctional parenchymal line or defect without junctional parenchyma. The prevalance and ultrasonographic features of the kidneys were evaluated. RESULTS: Morphological variation was noted in 71 cases(25%). the continuous type accounted for 54% of these, the discontinuous type for 38%, and junctional parenchymal defect or line without junctional parenchyma for 8%. In all cases, junctional parenchyma was located approximately at the junction of the upper and middle third of the kidny, and had the same echogenecity as the renal cortex. CONCLUSION: An understanding of the morphological variation of the kidney resulting from junctional renal parenchyma would be helpful in differentiating pseudo tumor from true renal neoplasm.

Correlation Between Contrast Enhancement of Portal Vein and Spleen Size in Dual-phase Spiral CT

URPOSE: To evaluate using spiral CT the effect of spleen size on blood flow in the portal venous system andto know the usefulness of this evaluation. MATERIALS AND METHODS: Fifty-one patients without evidence on spiralCT scan of abnormality thought to affect portal venous flow presented between December 1994 and June 1995. We measured spleen size and Hounsfield units of portal vein in dual-phase, and calculated the ratio of the unit inthe portal phase to that in the arterial phase. Spleen size was measured, using the length of X-axis by that of Z-axis on spiral CT scan. We then measured the correlation between the two values. CT was performed with a Somatom Plus-S scanner(Siemens, Erlangen, Germany). A total dose of 120ml of non-ionic contrast material(Ultravist) was administered at a rate of 3ml/sec. Arterial and portal phase were obtained after 30 seconds and 60 seconds fromthe beginning of the contrast agent injection. RESULTS: The correlation between spleen size and contrast enhancement of the portal vein was relatively significant(Pearson's correlation coefficient(r)=0.41801). CONCLUSIONS: Spleen size significantly affects portal venous flow on spiral CT scan. The evaluation of spleensize and contrast enhancement of the portal vein could be useful in the differential diagnosis of diseases which affect portal venous flow.