The Value of Multi-Shot Echoplanar MR Imaging in the Diagnosis of Focal Hepatic Lesions: Comparison with OtherStandard MR Imagings

PURPOSE: To determine the diagnositic value of multi-shot echo-planar MR imaging (EPI) in focal hepaticlesions by quantitatively comparing this with other standard MR sequences such as FSE(fast spin echo) T2WI,SE(spin echo) T1WI with and without Gd enhancement, FMPSPGR(fast multiplanar spoiled GRASS) with and without Gdenhancement. MATERIALS AND METHODS: Seventeen patients with 18 focal hepatic lesions were retrospectivelyreviewed by two abdominal radiologists. The pathological or clinical results of hepatic lesions were nine cases ofhemangioma, four of hepatocellular carcinoma, one of peripheral cholangiocarcinoma, one of simple cyst, and ofhemangioma. By dividing the data acquisition period into eight interleaved segments, multi-shot EPI images wereobtained. This T2W spin echo eight-shot EPIs of the liver in one 18 second breath hold was compared with otherpulse sequences. The foci of review were lesion detectablity and characterization. For the former, SNR(signal tonoise ratio) of the liver and CNR(contrast to noise ratio) of the lesion to the liver were calculated ;to evaluatethe latter, a separate calculation of lesion to liver CNR for each solid and nonsolid lesion group was performed. RESULTS: Among six pulse sequences, multi-shot EPI provided the poorest liver SNR (p<.01). With regard to lesionto liver CNR, EPI was superior to FMPSPGR, SE, and Gd SE, but inferior to FSE, Gd FMPSPGR(p<.01). For nonsolidlesions(hemangioma, cyst), EPI provided higher liver CNR than FMPSPGR, SE, or Gd-SE, but one that was poorer thanthat provided by FSE and Gd-FMPSPGR(p<.05). Among six pulse sequences, there was no statistically significantdifference in lesion to liver CNR in solid lesions. In the evaluation of liver to lesion CNR, multi-shot EPI wasalways inferior to FSE. CONCLUSION: We concluded that with regard to sensitivity and suseptibility, multi-shotEPI is inferior to T2W FSE. For SNR, EPI was the least satisfactory, though with the exception of FSE, EPIprovided a higher or comparable CNR than other pulse sequences, and this made lesion depiction easy, especially innonsolid lesions. It was, however, difficult to characterize lesions by using EPI alone to determine whether alesion was solid or nonsolid.

Physical Property and MR Imaging of Self-expandable Metallic Stents

PURPOSE: In order to furnish basic information prior to their use, the physical properties of variousself-expandable metallic stents and their MR characteristics were evaluated. MATERIALS AND METHODS: Fourcommercially available self-expandable metallic stents - Gianturco-the R sch, Hanaro, Memotherm, and Wallstent -were used in this study. For evaluation of the physical properties of each, hoop strengths and changes in radiiaccording to the degrees of longitudinal flexion were compared. Stent characteristics seen on MR images wereevaluated by measuring magnetic torque and by comparing images obtained in the vascular phantom using SE T1WI, FSET2WI, and FMPSPGR sequences. These images were analyzed with special emphasis on artifact size and the apparantshepe of the stent. RESULTS: Hoop strength was greatest in the Gianturco-R sch stent, followed by the Memotherm,Hanaro, and Wallstent. When flexed in the longitudinal axis, the radius of the Hanaro and Memotherm stentdecreased slightly as a larger flexion angle was applied. When this was 90degree, however, the connection of theGianturco-R sch stent collapsed. In contrast, the radius of the Wallstent became larger as a larger flexion anglewas applied. At the portal of the MR imaging unit, neither the Memotherm nor Wallstent showed deflection ; exceptfor a thin hyperintense rim at both ends, their images were excellent, and the lumina of these stents were alsoclearly seen. In contrast, the Gianturco-R sch and Hanaro stent demonstrated large deflexion and showed a severeblack-hole artifact. As a result, visualization of the stents themselves and their lumina was impossible. CONCLUSION: The Gianturco-R sch stent showed greater hoop strength than the others. The Wallstent showed goodlongitudinal flexibility and was thought to be effective in tortuous vessels. For follow-up after placement,especially when the nonferromagnetic Memotherm and Wallstent are used, MR imaging appears to be safe and useful.

Sequential Changes of Fresh and Fixed Specimen on MRI: Optimal Time Interval and Fixatives for Good Correlation with in Vivo State

PURPOSE: With the development of MR Imaging techniques, MRI and MR spectroseopy can be used to evaluatespecimens both in vivo and in vitro. For extracted tissue specimens we wished to obtain MR images which correlatedwell with images obtained in vive; the purpose of this study was to determine which fixatives and time intervalbest facilitated this objective. MATERIALS AND METHODS: After in vivo MR imaging, sample tissues of liver, renalcortex and renal medulla were obtained from ten healthy rabbits. Each tissue sample was placed in 75% ethanol, 10%formalin, and 0.9% normal saline and MR scans of each sample were performed at 30 minutes, 11/2, 3, 6, and 12hours after resection. Signal intensities of the images were measured and their sequential changes were evaluated. RESULTS: On T1WI, signal intensities of both tissue specimens fixed in formalin and ethanol and untreatedspecimens increased significantly during the first 30 minutes. The increased signal intensity then seen for 12hours was greater than on T2WI. On T2WI, signal ntensities of tissue specimens fixed in formalin and ethanol anduntreated specimens showed no significant changes within the first 30 minutes; after that, they showed less signalintensity change for 12 hours than on T1WI. CONCLUSION: To obtain MR images with the same signal intensities as invivo tissue, MRI of tissue specimens in the untreated state should be performed as soon as possible afterresection. On T2WI, signal intensities of tissue specimens were more similar to in vivo tissue than on T1WI.

Peripheral Cholangiocarcinoma: Three-Phase Helical CT Appearance

PURPOSE: To analyze the enhancement patterns and morphology of peripheral cholangiocarcinomas (CCs), as seen on three-phase helical CT. MATERIALS AND METHODS: Three-phase helical CT scans of 25 cases of 24 patients with pathologically-proven CCs were retrospectively reviewed. After intravenous administration of contrast media, scans of the hepatic arterial phase (HAP) were obtained at 30 seconds, of the portal venous phase (PVP) at 70 seconds, and of the delayed phase (DP) at 3 minutes. RESULTS: Linear, dense, marginal enhancement was seen in 17 CCs (68%), mainly on HAP images (64%) while thick, band-like, peripheral enhancement was seen in 18 (72%), on either PVP (52%) or DP (44%). Internal enhancement was observed in 23 CCs (92%) on PVP (68%) and/or DP (88%), and 19 CCs (76%) among them showed incomplete enhancement of stippled and/or septated patterns. Most (76%) were seen throughout all three phases to be hypoattenuating, as compared to the surrounding parenchyma. On HAP, wedge-shaped parenchymal enhancement was demonstrated at the periphery of 19 CCs (76%) suggesting impaired portal flow. Associated morphologic findings were satellate nodules (n=15, 60%), lymphadenopathy (n=14, 56%), focal dilatation of intrahepatic ducts around the tumor (44%), umbilication of the liver surface (50%), and clonorchiasis (44%). CONCLUSION: On three-phase helical CT, peripheral cholangiocarcinoma showed linear marginal enhancement on HAP, thick peripheral enhancement on PVP and/or DP, stippled and septated enhancing foci on DP, and peritumoral wedge enhancement on HAP. Associcated findings such as satellite nodules, focal dilatation of the intrahepatic ducts, umbilication of the tumor, and clonorchiasis were helpful.

Primary Epiploic Appendagitis: 4 Case Report

Primary epiploic appendagitis of the colon is a rare cause of abdominal pain and is a self-limiting disease. Double contrast barium enema showed a smooth extrinsic compression located anterolateraly to the involved colon. Ultrasonography revealed a non-compressible echogenic ovoid mass attached to the colon wall. On abdominal CT, all lesions were seen as pedunculated ovel fatty masses with surrounding streaky densities connected to the serosal surface of the adjacent colon. Follow up CT performed 13-25(mean 18) days later showed that during this intrval, the volume of the mass and extent of surrounding infiltrations had decreased.

Adenosquamous Carcinoma of the Liver: A Case Report

A case of primary adenosquamous carcinoma of the liver is reported. A large cystic mass with irregular enhancing wall was seen in the left lobe of the liver; multiple hepatic cysts and metastatic nodules were scattered in both lobes. Sonoguided needle biopsy was performed and on histopathology, adenosquamous carcinoma was diagnosed. The radiologic and pathologic relationships of this unusual neoplasm are discussed.

Placement of Central Venous Access via Subclavian Vein under Fluoroscopic Guidance with Intravenous Contrast Injection

PURPOSE: To evaluate the safety and efficacy of Hickman catheter placement via the subclavian vein under fluoroscopic guidance with intravenous contrast injection. MATERIALS AND METHODS: During an eleven-month period, 187 Hickman catheters were percutaneously placed in 167 consecutive patients in an interventional radiology suite. Subclavian venous puncture was made with injection of contrast medium into the peripheral venous line. After subclavian venous access had been obtained, a subcutaneous tunnel was created using a peel-away sheath or a tunneler. The Hickman catheters were inserted through a peel-away sheath, the distal tip of which was at the junction of the right atrium and the superior vena cava. RESULTS: One hundred and eighty-six Hickman catheters were successfully placed; the one failure was due to an atomical tortuosity of the vein(0.53%). Complications included one case of subclavian vein occlusion (0.53%); three of line occlusion by thrombus (1.6%); one of oozing at the suture site (0.53%); six of infection or inflammation (3.2%); eight of natural removal (4.2%); one case of air embolism (0.53%) and two of malposition (0.1%). Major complications such as pneumothorax or arterial puncture leading to mediastinal hemorrhage did not, however, occur. CONCLUSION: The authors concluded that radiologic Hickman catheter placement offers advantages over traditional approaches in terms of safety, convenience, and time and cost savings.

Differential Diagnosis of Submandibular Gland Lesions by CT

PURPOSE: We designed this study to determine the potentiality of the conventional CT in the diagnosis of submandibular gland lesions, especially in solving the diagnostic difficulty between neoplasm and inflammation. MATERIALS AND METHODS: We performed retrospective study of 35 patients and 2 of them had bilateral lesion of chronic inflammation, hence we analysed 37 cases of submandibular gland lesions. There were 9 cases of tumor (including 1 basal cell carcinoma, and 8 pleomorphic adenomas), 22 cases of chronic inflammation, and 6 cases of acute inflammation. CT scans were evaluated for the degree of enlargement (graded as iso, mild or marked enlargement), pattern of contrast enhancement, contour deformity of the gland, and several other items. RESULTS: Neoplastic masses showed more marked enlargement of the gland (77%) than chronic inflammation (22%). Degree of enhancement showed no difference among the lesions. Enhancement pattern was more inhomogeneous in neoplasm (80%) than in chronic inflammation (5%). Deformity of the natural contour of the gland was more frequent in neoplasm (all of 9 cases) than in chronic inflammation (32%). Acute inflammation showed internal low attenuation probably by abscess formation (3/6 cases) and overlying soft tissue swelling (all of 6 cases), and the age of patients was characteristically younger than other diseases (mean, 9 years). Several findings were more specific to diseases, such as dystrophic calcifications to pleomorphic adenoma (37%) and calculi with or without ductal dilatation to chronic inflammation (45%). CONCLUSION: Pre and postcontrast enhanced CT scan can serve as a predictor of pathologic nature of the submandibular gland lesions.

CT Diagnosis of Intestinal Obstruction: Findings and Usefulness

PURPOSE: To present the findings of intestinal obstruction and evaluate the value of CT in the diagnosis of intestinal obstruction. MATERIALS AND METHODS: We prospectively analyzed CT scans of twenty-two patients who were suspected to have intestinal obstruction. All 22 patients were confirmed with surgery:10 patients with adhesion, four with primary intestinal tumor, one with metastatic intestinal tumor, two with inflammatory bowel disease, two with intussusception, two with extrinsic compression by ovarian tumor, and one with inguinal hernia. The CT scans were evaluated with special attention to their causes, locations, and CT findings of intestinal obstruction. CT diagnosis and findings were compared with surgical results. RESULTS: Their causes were diagnosed correctly on CT scans in seventeen of 22 cases(77.3%). Locations of the intestinal obstruction were diagnosed correctly in 16 cases(72.7% ). The CT findings of intestinal obstruction were categorized into dilated proximal bowel loops with normal distal loops, thickening of the affected bowel wall, presence of the transitional zone, and no detectable abnormalities. The associated extraluminal findings were fat infiltration around the dilated bowel loops, ascites, and mesenteric lymphnodes enlargement. There were two limitations of CT in our study:first, no detectable differences between jejunum and ileum on CT scans, and second, difficulty in differential diagnosis between thickened bowel wall mimicking normal non-dilated segment and mechanical obstruction from tumors or inflammatory bowel diseases. CONCLUSION: We conclude that CT is useful method in the evaluation of causes and locations of intestinal obstruction and the demonstration of the associated extraluminal abnormalities.