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, Fisher's 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.

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.

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.

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.

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.

Effect of triolein emulsion on the blood-testis barrier in cats.

PURPOSE: Although the blood-testis barrier (BTB) is beneficial physiologically, it acts as an obstacle to chemotherapy. We wished to determine whether a triolein emulsion could alter the permeability of the BTB in cats. MATERIALS AND METHODS: An emulsion of 0.05-mL triolein in 20 mL of saline was infused into the abdominal aorta just proximal to the branching of the renal arteries of each of 15 cats (embolic group). As controls, 12 cats were each similarly infused with 20 mL of normal saline (control group). Pre and postcontrast MR images were obtained 30 minutes and 2 hours after embolization. The images were analyzed for the presence and degree of contrast enhancement (qualitative analysis), and the contrast enhancement ratios (CER) derived from one testis of each animal were compared and statistically analyzed by the mixed linear model (quantitative analysis). RESULTS: Contrast enhancement of the testis was observed in both groups at both time points, but it was more prominent in the embolic group. The CERs in the embolic group (0.63 at 30 minutes, 0.42 at 2 hours) were significantly higher than in the control group (0.36 at 30 minutes, 0.28 at 2 hours; P = 0.0001). In each group, the CERs at 2 hours were significantly lower than those at 30 minutes (P = 0.006). CONCLUSION: Intra-arterial infusion of triolein emulsion increased the permeability of the BTB. This result may be useful in future studies of BTB disruptions caused by fat emulsions.

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.

Experimental cerebral fat embolism: embolic effects of triolein and oleic acid depicted by MR imaging and electron microscopy.

BACKGROUND AND PURPOSE: In fat embolism, free fatty acid is more toxic than neutral fat in terms of tissue damage. We evaluated the hyperacute embolic effects of triolein and oleic acid in cat brains by using MR imaging and electron microscopy. METHODS: T2-weighted imaging, diffusion-weighted imaging, and contrast-enhanced T1-weighted imaging were performed in cat brains after the injection of triolein (group 1, n = 8) or oleic acid (group 2, n = 10) into the internal carotid artery. MR images were quantitatively assessed by comparing the signal intensity ratios of the lesions with their counterparts on T2-weighted images, apparent diffusion coefficient (ADC) maps, and contrast-enhanced T1-weighted images. Electron microscopic findings in group 1 were compared with those in group 2. RESULTS: Qualitatively, MR images revealed two types of lesions. Type 1 lesions were hyperintense on diffusion-weighted images and hypointense on ADC maps. Type 2 lesions were isointense or mildly hyperintense on diffusion-weighted images and isointense on ADC maps. Quantitatively, the signal intensity ratios of type 1 lesions in group 2 specimens were significantly higher on T2-weighted images (P =.013)/(P =.027) and lower on ADC maps compared with those of group 1. Electron microscopy of type 1 lesions in both groups revealed more prominent widening of the perivascular space and swelling of the neural cells in group 2, in contrast to notable endothelial defects in group 1. CONCLUSION: MR and electron microscopic data on cerebral fat embolism induced by either triolein or oleic acid revealed characteristics suggestive of both vasogenic and cytotoxic edema in the hyperacute stage. Tissue damage appeared more severe in the oleic acid group than in the triolein group.