MR Imaging of Hepatocellular Carcinoma: Usefulness of Four-Phase Dynamic Imaging Including Early ArterialPhase

PURPOSE: To evaluate the usefulness of four-phase dynamic MR imaging technique by analyzing the imagingfeatures of hepatocellular carcinoma(HCC). MATERIALS AND METHODS: We reviewed four-phase dynamic MR images of 63lesions in 38 patients. MR imaging of the whole liver on gradient T1-weighted sequence was obtained at 10seconds(phase I), 35 seconds(phase II), 60 seconds(phase III), and 5 minutes(phase IV) after the start ofGd-DTPA(0.1mmol/kg) hand injection(3-4cc/sec) through the vein. We evaluated the degree of lesional contrastenhancement during each phase by comparing surrounding liver parenchyma, and analyzed signal intensity in lesionsover and less 2cm, respectively. RESULTS: The number of lesions showing high signal intensity compared withsurrounding liver parenchyma was 52(83%)during phase I, 30(48%) during phase II, 12(19%) during phase III, and 4(6%) during phase IV. During each phase, the number of lesions with signal intensity lower than that ofsurrounding liver parenchyma was 7(11%), 2(3%), 7(11%) and 21(33%), respectively. Thirty-four lesions wereenhanced only during phase I and eleven during only phase II. In tumors less than 2cm(n=40), more enhanced lesionswere during phase I(n=33) than more during phase II(n=16)(p=.0020). CONCLUSION: During each phase, four-phasedynamic MR imaging is useful for the effective detection of HCC showing varying degrees of contrast enhancement.

Infiltrating Ductal Carcinoma with Mammographic 'Halo Sign' Correlation with Histopathology

PURPOSE: To analyze and correlate mammographic/ sonographic features with pathologic findings in patientswith infiltrative ductal carcinoma with the mammographic 'halo sign'. MATERIALS AND METHODS: We retrospectivelyreviewed 27 cases of surgically confirmed infiltrative ductal breast carcinoma with the mammographic 'halo sign',analysing the mammographic/sonographic findings, clinical records and pathologic findings. RESULTS: Twenty-sevenpatients with infiltrating ductal breast carcinoma with the mammographic 'halo sign' were aged 32-72 (mean 49+/-12)years. For periods of between 2 days and 5 months(mean, 1.9 months), all had complained of a palpable mass.Histologic sections indicated parenchymal compression(27/27), microscopic infiltration of tumor margin(11/27) andparenchymal fat compression(15/27), without a true capsule. Infiltrating ductal carcinomas with the mammographic'halo sign' were nuclear grade 1 (17/27) or histologic grade III (14/27). Mammography (complete halo:3;partialhalo:24) showed a round(15/27) or macrolobulated (9/27) mass (size : 2.5+/-1cm) which showed partialspiculation(17/27) or-rarely-calcification(2/27). Sonography revealed a hypoechoic mass with a thinboundary(13/15);in five of these 13 cases, pathologic examination revealed microscopic infiltration of the tumormargin. Bilateral shadowing (8/15), posterior enhancement(13/15), and heterogeneous internal echogenicity(13/15)were also noted on sonography. CONCLUSION: When correlated with the histopathologic findings, infiltrating ductalbreast carcinoma with the 'halo sign' showed a relatively poor pathologic grade, which is known to be one of theprognostic factors. Surrounding parenchyma and fat compression at the margin of a tumor are considered to be oneof the causes of the mammographic 'halo sign'.

Differential Diagnosis of the Pancreatic Diseases: Significance of Perivascular Changes at Celiac trunk andSuperior Mesenteric Artery on CT

PURPOSE: To classify perivascular change in the celiac trunk and SMA occurring in pancreatic disease and toevaluate its significance in differential diagnosis. MATERIALS AND METHODS: In 73 patients with pancreaticdisease (42, acute pancreatitis; 14, chronic pancreatitis; 17, panreatic cancer) abdominal CT findings wereretrospectively reviewed. We defined " infiltration" as linear or irregular density and "thickening" as presenceof a soft tissue mantle surrounding the vessel, and statistically evaluated the usefulness of these factors forthe differential diagnosis of pancreatic diseases. RESULTS: In 13/42 cases of acute pancreatitis (31%), 4/14 ofchronic pancreatitis (28.6%), and 6/17 of pancreatic cancer (35.3%), periceliac infiltration was observed; thefrequencies were not statistically significant (p=0.916). Peri-SMA infiltration was demonstrated in 9/42 of acutepancreatitis (21.4%), 4/14 of chronic pancreatitis (28.6%), and 5/17 of pancreatic cancer (29.4%); again, thesefrequencies were not statistically significant (p=0.758). Thickening of the celiac trunk and SMA was observed onlyin pancreatic cancer, in 3/17 (17.6%) and 7/17(41.2%) cases, respectively, with statistical significance (p<0.05). CONCLUSION: Thickening of the celiac trunk and SMA is a valuable finding in the differential diagnosis ofpancreatic inflammatory disease and pancreatic cancer. When applied to the differential diagnosis of pancreaticdisease, perivaseular change should be classified as either infiltration or thickening.

Chemical Saturation Breath-hold Fast MR Imaging for Characterization of Regional Fatty Changes in Liver

PURPOSE: To assess the usefulness of breath-hold fast MR imaging of liver with fat suppression (FS) by application of chemical saturation technique in the diagnosis of regional fatty changed suspected in sonography. MATERIALS AND METHODS: Thirteen patients who had focal lesions with diffuse, homogeneous signal changes after FS through chemical saturation technique without additional changes of imaging parameter during MR imaging of liver were selected. T1-weighed fast low-angle shot and T2-weighted turbo spin-echo sequences were obtained with or without FS during each single breath-holding session. Subjective changes of signal intensity between the pre-FS and the FS images were compared with the sonographic findings in each lesion. RESULTS: Seven lesions of decreased signal intensity after FS on T1 or T2-weighted images, including three lesions only at FS T1 images, were regarded as focal fat infiltration. All seven lesions had compatible sonographic findings as homogenously echogenic areas. Another six lesions of subjectively increased signal intensity including two lesions only at FS T2 images were regarded as focal fat sparing. All six lesions had sonographic findings as homogenous echo poor areas suggesting focal fat sparing. In cases regarded as fat infiltration, score changes were more prominent at FS T1 images than FS T2 images(p=0.0002). In cases regarded as fat sparing, score changes were more prominent at FS T2 images than FS T1 images(p=0.042). CONCLUSION: Breath-hold fast T1 and T2-weighted MR imaging with and without chemical saturation pre-pulse may be sufficient for characterization of regional fatty changes in the different ferential diagnosis of focal hepatic lesion found at sonography.