Multidetector CT features of mesenteric vein thrombosis.

Mesenteric vein thrombosis (MVT) accounts for 5%-15% of all mesenteric ischemic events and is classified as either primary or secondary. Primary MVT is idiopathic, whereas secondary MVT can result from a variety of underlying diseases and risk factors, including primary hypercoagulable states or prothrombotic disorders, myeloproliferative neoplasms, cancer (most frequently of the pancreas or liver), diverse inflammatory conditions, recent surgery, portal hypertension, and miscellaneous causes such as oral contraceptives or pregnancy. Clinical symptoms of MVT are rather nonspecific and are mainly characterized by abdominal pain. The mortality rate for MVT remains high, since even now the diagnosis is often delayed. Multidetector computed tomography (CT) is the modality of choice in this context. Although venous bowel ischemia occurs only infrequently with MVT, radiologists should be familiar with its multidetector CT features. Familiarity with the possible causes of MVT, the underlying pathogenic mechanisms associated with MVT, and the correlation between multidetector CT features and these pathogenic mechanisms is necessary to optimize medical management and improve patient care.

Experimental and clinical radiofrequency ablation: proposal for standardized description of coagulation size and geometry.

BACKGROUND: Radiofrequency (RF) ablation is used to obtain local control of unresectable tumors in liver, kidney, prostate, and other organs. Accurate data on expected size and geometry of coagulation zones are essential for physicians to prevent collateral damage and local tumor recurrence. The aim of this study was to develop a standardized terminology to describe the size and geometry of these zones for experimental and clinical RF. METHODS: In a first step, the essential geometric parameters to accurately describe the coagulation zones and the spatial relationship between the coagulation zones and the electrodes were defined. In a second step, standard terms were assigned to each parameter. RESULTS: The proposed terms for single-electrode RF ablation include axial diameter, front margin, coagulation center, maximal and minimal radius, maximal and minimal transverse diameter, ellipticity index, and regularity index. In addition a subjective description of the general shape and regularity is recommended. CONCLUSIONS: Adoption of the proposed standardized description method may help to fill in the many gaps in our current knowledge of the size and geometry of RF coagulation zones.

Pulse-inversion harmonic imaging improves lesion conspicuity during US-guided biopsy.

PURPOSE: To assess the feasibility of percutaneous biopsy of low-conspicuity focal liver lesions with use of pulse-inversion harmonic imaging (PIHI) guidance in the late phase after injection of microbubble contrast agent. MATERIALS AND METHODS: Twelve patients referred for ultrasound (US)-guided biopsy had liver lesions lacking adequate conspicuity to undergo biopsy under conventional ultrasound (US) guidance. They underwent biopsy procedures performed with the use of PIHI guidance in the late phase after injection of Levovist. The conspicuity of lesions, procedure time, number of passes, and success and complication rates were documented and compared to a control group. The control group consisted of retrospective analysis of 19 patients who had undergone conventional US-guided biopsy procedures performed by the same radiologist. RESULTS: After contrast material injection, all lesions had sufficient increases in conspicuity to be targeted under PIHI guidance. Procedure time was prolonged in the PIHI group (66 minutes; range, 30-120 min; vs control, 33 min; range, 15-77 min; P <.01, Wilcoxon signed-rank test). The number of passes was greater in the PIHI group (1.9 +/- 0.3; vs control, 1.4 +/- 0.6; P <.01, chi(2) test). No statistically significant difference was observed when comparing success and complication rates. CONCLUSION: PIHI in the late phase after injection of Levovist generated clear delineation of focal liver lesions in all cases, allowing an accurate and safe sampling. This technique broadens the scope of US-guided biopsy to lesions lacking adequate conspicuity on conventional US.

Feasibility and effectiveness of using coronary stents in the treatment of hepatic artery stenoses after orthotopic liver transplantation: preliminary report.

OBJECTIVE: Our aim is to evaluate the feasibility, efficacy, and patency of using coronary stents for the treatment of hepatic artery stenosis after liver transplantation. CONCLUSION: Hepatic artery stenosis after liver transplantation can be treated using coronary stents. The low rate of complication, high technical success, and 1-year patency rates are encouraging.

Radio-frequency tissue ablation of the liver: in vivo and ex vivo experiments with four different systems.

The aim of this study was to test the efficacy of four different radio-frequency ablation (RFA) systems in normal hepatic parenchyma in large animals. The RFA was applied to pig livers in vivo and to calf livers ex vivo using the Radionics cluster needle, RITA starburst XL needle, Radiotherapeutics Le Veen 4.0 needle, and the Berchtold 14-G saline-perfused 15-mm active-tip needle based on constructor specifications. The volume of tissue coagulation from RF was calculated from measurements of the vertical diameter (Dv) and transverse diameter (Dt). Lesion shape was characterized using the ratio between Dt/Dv. Radiotherapeutics and RITA produced in vivo lesion volume of 42+/-10, 39+/-4 cm3 with a reproducible spherical shape (Dt/Dv of 1.01+/-0.16 and 0.97+/-0.1, respectively). Radionics produced in vivo RF lesions volume of 29+/-11 cm3) with an ovoid shape (Dt/Dv 0.88+/-0.09). The RF lesions with the Berchtold device could not be assessed in vivo as 5 of 8 animals died during treatment. Ex vivo RF lesions had similar volumes with each system; however, the Radiotherapeutics device produced more reproducible shaped lesions than the other systems. In our experimental study, we found no difference between expandable needle systems in vivo. Cooled needles produced slightly smaller and ovoid shape in vivo lesions.