Suk Hong Lee

Biliary MR Imaging with Gd-EOB-DTPA and Its Clinical Applications

The hepatocyte-specific contrast agent gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) was developed to improve the detection and characterization of focal liver lesions at magnetic resonance (MR) imaging. Approximately 50% of the injected dose is taken up into the functional hepatocyte and is excreted via the biliary system. Because of this property, Gd-EOB-DTPA has the potential to be a biliary contrast agent. When combined with T2-weighted MR cholangiography, Gd-EOB-DTPA-enhanced MR imaging can allow morphologic and functional assessment of the biliary system. Gd-EOB-DTPA-enhanced MR cholangiography could be effective in evaluation of biliary anatomy, differentiation of biliary from extrabiliary lesions, diagnosis of cholecystitis, assessment of bile duct obstruction, detection of bile duct injury including leakage and stricture, evaluation of biliary-enteric anastomoses, postprocedure evaluation, differentiation of biloma from other pathologic conditions, and evaluation of sphincter of Oddi dysfunction. However, the clinical applications of this imaging technique have not yet been fully explored, and further investigations are needed to determine the utility of Gd-EOB-DTPA-enhanced MR cholangiography in a clinical setting.

T-Configured Dual Stent Placement in Malignant Biliary Hilar Duct Obstructions with a Newly Designed Stent

PURPOSE To evaluate the technical success and clinical efficacy of T-configured dual stent placement in the management of malignant biliary hilar duct obstructions with a newly designed stent. MATERIALS AND METHODS Between January 2001 and July 2002, 57 patients with malignant biliary hilar duct obstruction were treated with percutaneous transhepatic placement of two self-expandable metallic endoprostheses in a T configuration with use of a newly designed stent. The patients ranged in age from 46 to 85 years and included 37 men and 20 women. RESULTS Stent placement with two endoprostheses was successful in all patients. The mean survival and stent patency times were 193.6 days (range, 7-442 days) and 170.3 days (range, 7-305 days), respectively. There were no statistical differences in age, sex, or Bismuth type. CONCLUSION T-configured dual stent placement with a newly designed stent is simple, safe, and reliable in achieving bilateral internal bile drainage in patients with malignant biliary hilar obstructions.

Long-term follow-up after endovascular stent placement for treatment of nutcracker syndrome.

posed in which the intrahepatic PV is accessed directly via the intrahepatic inferior vena cava under intravascular US guidance and a shunt is subsequently created with use of a covered stent (2,3). Another nonsurgical approach to creation of a portosystemic shunt is the intravascular US– guided creation of a transvenous extrahepatic portacaval shunt (4). If the target PVs are located cranially to the hepatic veins or lie at the same caudocranial level but are separated anteroposteriorly from the hepatic veins, accessing the PV from the transjugular route can be difficult or impossible, as in our case (5). One technique to successfully deal with this anatomy is the creation of TIPS via the femoral route (6). Our approach also created a hemodynamically significant shunt by dilating and stent-implanting a small preexisting intrahepatic portovenous fistula. Portovenous shunts occur primarily in patients with chronic liver disease, especially liver cirrhosis. Doppler US with a pulsatile trior biphasic spectral pattern suggests the presence of a portosystemic shunt. Numerous alternative approaches to nonsurgical creation of a portosystemic shunt are available when standard approaches fail. In the rare instances in which a PV–hepatic vein fistula is present, TIPS can be created by placing a stent in this fistula.

Biliary abnormalities associated with portal biliopathy: evaluation on MR cholangiography.

OBJECTIVE The purpose of our study was to evaluate the MRI features of portal biliopathy. CONCLUSION MR cholangiography coupled with dynamic 3D gradient-echo imaging could not only detect portal vein occlusion, cavernous transformation, and gallbladder varices but is also suitable for delineating associated bile duct abnormalities.

Early development of vasogenic edema in experimental cerebral fat embolism in cats: correlation with MRI and electron microscopic findings.

Kim HJ, Lee CH, Lee SH, et al. Early development of vasogenic edema in experimental cerebral fat embolism in cats: Correlation with MRI and electron microscopic findings. Invest Radiol 2001;36:460–469. rationale and objectives. To evaluate the magnetic resonance imaging and electron microscopic findings of the hyperacute stage of cerebral fat embolism in cats and the time needed for the development of vasogenic edema. methods.Magnetic resonance imaging was performed at 30 minutes (group 1, n = 9) and at 30 minutes and 1, 2, 4, and 6 hours after embolization with triolein (group 2, n = 10). As a control for group 2, the same acquisition was obtained after embolization with polyvinyl alcohol particles (group 3, n = 5). Magnetic resonance images were analyzed qualitatively and quantitatively. Electron microscopic examination was done in all cats. results.In group 1, the lesions were iso- or slightly hyperintense on T2-weighted (T2W) and diffusion-weighted (DWIs) images, hypointense on the apparent diffusion coefficient (ADC) map image, and markedly enhanced on the gadolinium-enhanced T1-weighted images (Gd-T1WIs). In group 2 at 30 minutes, the lesions were similar to those in group 1. Thereafter, the lesions became more hyperintense on T2WIs and DWIs and more hypointense on the ADC map image. The lesions were enhanced on Gd-T1WIs at all acquisition times. In group 3, the lesions showed mild hyperintensity on T2WIs at 6 hours but hypointensity on the ADC map image from 30 minutes, with a tendency toward a greater decrease over time. The lesions were not enhanced on Gd-T1WIs at any time point. Electron microscopic findings revealed discontinuity of the capillary endothelial wall, perivascular and interstitial edema, and swelling of glial and neuronal cells in groups 1 and 2. Cellular swelling and interstitial edema were more prominent in group 2. In group 3, interstitial edema was seen; however, discontinuity of the endothelial wall was absent. conclusions.The lesions were hyperintense on T2WIs and DWIs, hypointense on the ADC map image, and enhanced on Gd-T1WIs. On electron microscopy, the lesions showed cytotoxic and vasogenic edema with disruption of the blood-brain barrier. Vasogenic edema seems to develop within 30 minutes in cerebral fat embolism in cats.

Magnetic resonance imaging and histologic findings of experimental cerebral fat embolism.

Rationale and Objectives:The purpose of this study was to determine whether cerebral fat embolism demonstrated reversible or irreversible findings in magnetic resonance (MR) imaging over time and to compare the features in MR images with histologic findings in a cat model. Materials and Methods:MR images were obtained serially at 2 hours, 1 and 4 days, and 1, 2, and 3 weeks after embolization with 0.05 mL of triolein into the internal carotid artery in 19 cats. Any abnormal signal intensity and change in the signal intensity were evaluated on T2-weighted images, T1-weighted images, diffusion-weighted images (DWIs; including apparent diffusion coefficient [ADC] maps), and gadolinium-enhanced T1-weighted images (Gd-T1WI) over time. After MR imaging at 3 weeks, brain tissue was obtained and evaluated for light microscopic (LM) examination using hematoxylin-eosin and Luxol fast blue staining. For electron microscopic examination, the specimens were obtained at the cortex. The histologic and MR findings were compared. Results:The embolization lesions showed hyperintensity on T2-weighted images, hyperintensity, or isointensity on DWIs, hypointensity, or isointensity on ADC maps and contrast enhancement on Gd-T1WIs at 2 hours. The T2-weighted hyperintensity extended to the white matter at day 1 and decreased thereafter. Contrast enhancement decreased continuously from day 1, and hyperintensity on DWI decreased after day 4. Hypointensity on ADC maps became less prominent after day 4. By week 3, most lesions had reverted to a normal appearance on MR images and were correlated with LM findings. However, small focal lesions remained in the gray matter of 8 cats and in the white matter of 3 cats on MR images, and this correlated with the cystic changes on LM findings. Electron microscopic examination of the cortical lesions that reverted to normal at week 3 in MR images showed that most of these lesions appeared normal but showed sporadic intracapillary fat vacuoles and disruption of the endothelial walls. Conclusions:The embolized lesions of the hyperacute stage were of 2 types: type 1 lesions, showing hyperintensity on DWIs and hypointensity on ADC maps, have irreversible sequelae, such as cystic changes; whereas type 2 lesions, showing isointensity or mild hyperintensity on DWIs and ADC maps, reverted to a normal appearance in the subacute stage.

Near drowning: thin-section CT findings in six patients.

Purpose The purpose of this study was to assess the thin-section CT findings of near drowning in six patients. Method Thin-section (1 mm collimation) CT scans of six patients who experienced near drowning were retrospectively analyzed. The CT scans were performed 0–5 days (median 1 day) after near drowning. Results Thin-section CT findings included bilateral patchy or diffuse areas of ground-glass attenuation (n = 6) with geographic pattern (n = 3) and fine intralobular reticular opacities (“crazy-paving” appearance) (n = 3), ill-defined centrilobular nodules (n = 4), and air-space consolidation (n = 1). Distribution of ground-glass attenuation was predominantly central (n = 4) or diffuse (n = 2). Interstitial pulmonary emphysema and pneumomediastinum were present in two patients. Conclusion The thin-section CT findings of near drowning consist of ground-glass opacities with or without associated reticular opacities and centrilobular nodules.

Localization of pulmonary nodules with lipiodol prior to thoracoscopic surgery

Background Preoperative localization with lipiodol for identifying small or deeply seated pulmonary nodules is simple and useful for thoracoscopic surgery. Although several studies about performance and complication rates of lipiodol localization have been reported, there has been no report about the performance and complication rates of lipiodol localization with regard to the CT appearance of pulmonary nodules. Purpose To evaluate the performance and complication rates of localization of pulmonary nodules with lipiodol prior to video-assisted thoracoscopic surgery with regard to the CT appearance of nodules. Material and Methods After institutional review board approval and informed consent were obtained, lipiodol marking was performed in 67 patients (33 men and 34 women; mean age 58 years) with 68 nodules. All nodules were marked with 0.4–0.5 mL lipiodol under CT guidance on the day of surgery. The size of the targeted nodule and the shortest distance to the accessible pleural surface were measured. Lipiodol accumulation of a targeted nodule was scored by use of a four-point scale (0: none, 1: within 1 cm around a nodule, 2: partial accumulation within a nodule, 3: total accumulation within a nodule). Any complications after localization of nodules were noted. We analyzed the score of lipiodol accumulation and the presence of complications for the CT appearance of pulmonary nodules using the Mann Whitney U test, Fishers exact test and the Kruskall Walis test. Results The average nodule size was 11.4 mm (range 3.0–28.3 mm) and the average distance to the pleural surface was 13.7 mm (range 0–51.4 mm). Lipiodol accumulation scores of nodules were as follows: score 3 (n = 19, 28%), score 2 (n = 37, 54%), score 1 (n = 11, 16%), and score 0 (n = 1, 2%). Lipiodol accumulation scores of nodules were different according to the size of nodules (Kruskal Wallis test, p = 0.023). Pneumothorax after localization occurred in 20 (29%) patients and the incidence was higher in nodules located in the subpleural area (Mann Whitney U test, p = 0.048). Pulmonary hemorrhage along the needle tract occurred in five (7%) patients and was more frequent in patients with deep nodules as compared to shallow nodules (Mann Whitney U test, p < 0.001). Conclusion Lipiodol marking under CT guidance is a useful and safe procedure for the intraoperative localization of pulmonary nodules. Of variable CT findings, lesion size is important to determine the degree of lipiodol accumulation and the lesion depth is the most important feature for the development of postprocedural complications.

Pulmonary tuberculosis in five young infants with nursery exposure: clinical, radiographic and CT findings

Abstract Clinical, radiographic (n = 5) and CT findings (n = 4) of five Korean infants ranging in age from 2 to 3 months with confirmed tuberculosis were retrospectively analysed. All of the patients were symptomatic, anergic to tuberculin, and had a positive culture of Myobacterium tuberculosis in gastric aspirates. The probable source of infection was the hospital in which they were born. CT scans demonstrated hilar and mediastinal lymph node enlargement with central low attenuation and peripheral enhancement in all cases. CT may be useful in diagnosis by demonstrating characteristic adenopathy and disseminated disease in young infants.

MR appearance of normal and abnormal bile: Correlation with imaging and endoscopic finding

Identification of abnormal bile related to various pathological processes in the pancreaticobiliary tract can be important in the diagnosis of disease and the determination of appropriate treatment. Magnetic resonance (MR) imaging can allow comprehensive evaluation of abnormal bile because MR usually provides better tissue characterization than other imaging modalities. A high-intensity signal from bile is frequently encountered on T1-weighted images and can be seen in concentrated bile, sludge, stones, or hemobilia. Contrast-enhanced MR features, such as inhomogeneous hepatic enhancement in the arterial phase and papillitis or mild-to-moderate bile duct wall thickening with enhancement, along with clinical characteristics, may suggest clinically significant bile, such as sludge or purulent bile, rather than merely concentrated bile. A history of trauma and appropriate imaging findings in the hepatobiliary tract can support a diagnosis of hemobilia. MR imaging may assist in diagnosing intraductal papillary mucinous neoplasm of the bile duct via detection of an intraductal mass or several indirect signs, suggesting a large amount of mucin. Additionally, Gd-EOB-DTPA-enhanced MR may delineate mucin as a filling defect surrounding hyperintense bile. A floating filling defect on all MR sequences is helpful in discriminating pneumobilia from other intraluminal filling defects. Familiarity with the various different MR features of abnormal bile signals can therefore facilitate accurate diagnosis and treatment.