Jean-Pierre Cercueil

Quantification of Liver Fat Content: Comparison of Triple-Echo Chemical Shift Gradient-Echo Imaging and in Vivo Proton MR Spectroscopy

PURPOSE To validate a triple-echo gradient-echo sequence for measuring the fat content of the liver, by using hydrogen 1((1)H) magnetic resonance (MR) spectroscopy as the reference standard. MATERIALS AND METHODS This prospective study was approved by the appropriate ethics committee, and written informed consent was obtained from all patients. In 37 patients with type 2 diabetes (31 men, six women; mean age, 56 years), 3.0-T single-voxel point-resolved (1)H MR spectroscopy of the liver (Couinaud segment VII) was performed to calculate the liver fat fraction from the water (4.7 ppm) and methylene (1.3 ppm) peaks, corrected for T1 and T2 decay. Liver fat fraction was also computed from triple-echo (consecutive in-phase, opposed-phase, and in-phase echo times) breath-hold spoiled gradient-echo sequence (flip angle, 20 degrees), by estimating T2* and relative signal intensity loss between in- and opposed-phase values, corrected for T2* decay. Pearson correlation coefficient, Bland-Altman 95% limit of agreement, and Lin concordance coefficient were calculated. RESULTS Mean fat fractions calculated from the triple-echo sequence and (1)H MR spectroscopy were 10% (range, 0.7%-35.6%) and 9.7% (range, 0.2%-34.1%), respectively. Mean T2* time was 14.7 msec (range, 5.4-25.4 msec). Pearson correlation coefficient was 0.989 (P < .0001) and Lin concordance coefficient was 0.988 (P < .0001). With the Bland-Altman method, all data points were within the limits of agreement. CONCLUSION A breath-hold triple-echo gradient-echo sequence with a low flip angle and correction for T2* decay is accurate for quantifying fat in segment VII of the liver. Given its excellent correlation and concordance with (1)H MR spectroscopy, this triple-echo sequence could replace (1)H MR spectroscopy in longitudinal studies.

Visceral fat area is an independent predictive biomarker of outcome after first-line bevacizumab-based treatment in metastatic colorectal cancer

Background Adipose tissue releases angiogenic factors that may promote tumour growth. Objective To determine whether body mass index (BMI), subcutaneous fat area (SFA) and visceral fat area (VFA) are associated with outcomes in patients given first-line bevacizumab-based treatment for metastatic colorectal cancer (MCC). Patients CT was used to measure SFA and VFA in 120 patients with MCC who received bevacizumab-based treatment (bevacizumab group, n=80) or chemotherapy alone (chemotherapy group, n=40) as first-line treatment. Associations linking BMI, SFA and VFA to tumour response, time-to-progression (TTP) and overall survival (OS) were evaluated. Results In the bevacizumab group, median follow-up lasted for 24 months (3–70). BMI, SFA and VFA values above the median (ie, high BMI, high VFA and high SFA) were significantly associated with absence of a response. TTP was shorter in patients with high BMI (9 vs 12 months; p=0.01) or high VFA (9 vs 14 months; p=0.0008). High VFA was associated with shorter OS (p=0.0493). By multivariate analysis, high VFA was independently associated with response, TTP and OS (HR=7.18, p=0.008, HR=5.79, p=0.005 and HR=2.88, p=0.027, respectively). In the chemotherapy group, median follow-up lasted for 30 months (4–84). BMI, SFA and VFA were not associated with response, TTP or OS. In the whole population, interaction between VFA and bevacizumab administration was significant for response (OR=3.31, p=0.005) and TTP (HR=1.64, p=0.022), thereby confirming the results. Conclusion This study provides the first evidence that high VFA independently predicts a poorer outcome in patients given first-line bevacizumab-based treatment for MCC. However, this predictive biomarker needs to be validated in a different dataset.

Nonalcoholic fatty liver is not associated with carotid intima-media thickness in type 2 diabetic patients.

OBJECTIVE Nonalcoholic fatty liver disease (NAFLD) is commonly associated with obesity, metabolic syndrome, and type 2 diabetes. Several studies suggest that NAFLD is independently associated with an increased risk of cardiovascular disease in nondiabetic subjects. In type 2 diabetic subjects, the link between fatty liver and atherosclerosis is less clear. In this study, we set out to determine, whether fatty liver content, evaluated using 1H-magnetic resonance spectroscopy, a very precise imaging technique, was associated with atherosclerosis in people with type 2 diabetes. RESEARCH DESIGN AND METHODS A total of 101 patients with type 2 diabetes mellitus were included in this study. Liver fat (1H-magnetic resonance spectroscopy) and carotid intima media thickness (IMT) were measured. RESULTS Sixty-one (60.3%) patients had steatosis (hepatic triglyceride content greater than 5.5%). Liver fat content was correlated with fasting serum triglycerides (r = 0.22; P = 0.02) and alanine aminotransferase (r = 0.42; P = 0.0001). Sixty-eight percent of subjects with severe steatosis (hepatic triglyceride content greater than 15%) had aspartate aminotransferase in the normal range. Age was strongly correlated with IMT (r = 0.37; P = 0.0002). Steatosis did not correlate with IMT (r = -0.03; P = 0.75). There was no significant difference between the two groups (with and without hepatic steatosis) for IMT values. CONCLUSIONS this study suggests that in people with type 2 diabetes, fatty liver is not associated with cardiovascular disease. In a diabetic population, it seems that fatty liver is not a determinant factor associated with carotid IMT.

Liver diffusion-weighted MR imaging: the tower of Babel?

There is a growing amount of literature regarding diffusion-weighted imaging (DWI) of the liver. The apparent diffusion coefficient (ADC) was introduced in 1986 and is used extensively in studies. However, methods for calculating ADC vary considerably and the value of the ADC strongly depends on the b values chosen for its calculation. Indeed, the ADC incorporates the effects of both diffusion and perfusion, which can vary independently. Since signal attenuation as a function of b follows a bi-exponential pattern, other diffusion/perfusion coefficients can be calculated using DWI, and these may provide more meaningful measurements than the ADC. The absence of standardization for both the terminology and the methodology in DWI of the liver makes it difficult for readers to understand the technique used and strongly limits comparisons between studies. Here, we review the main principles of DWI of the liver, the limits of the ADC, and the exciting capabilities of multi-parametric DWI. We also insisted on the need for a common language for DWI of the liver.

Transcatheter Arterial Embolization of Splenic Artery Aneurysms and Pseudoaneurysms: Short- and Long-Term Results

We evaluated outcomes of endovascular treatment of splenic artery aneurysms and pseudoaneurysms. From April 2002 to May 2007, 17 patients (mean age 55.2 years, range 17-82) with splenic artery aneurysms (n = 7) or pseudoaneurysms (n = 10) underwent endovascular treatment. Six patients were asymptomatic, three had symptomatic nonruptured aneurysms, and eight had ruptured aneurysms. Lesions were in the proximal splenic artery (n = 5), intermediate splenic artery (n = 3), splenic hilum (n = 6), or parenchyma (n = 3). Embolization was with microcoils by sac packing (n = 8), sandwich occlusion of the main splenic artery (n = 4), or cyanoacrylate glue into the feeding artery (n = 4). Computed angiotomography was done within the first month and magnetic resonance angiography after 6 and 12 months, then yearly. Mean follow-up was 29 months (range 1-62). Exclusion of the aneurysm was achieved in 16 (94.1%) patients. One patient with an intraparenchymal pseudoaneurysm underwent splenectomy after failed distal catheterization. No major complications occurred. Postembolization syndrome developed in four patients, who had radiographic evidence of splenic microinfarcts. Transcatheter embolization of splenic artery aneurysms/pseudoaneurysms is safe and effective and may induce less morbidity than open surgery, in particular by preserving the spleen. Coil artifacts may make magnetic resonance angiography preferable over computed tomography for follow-up.

Endovascular Therapeutic Embolisation: An Overview of Occluding Agents and their Effects on Embolised Tissues

Vascular embolisation agents are particles or fluids that can be released into the bloodstream through a catheter to mechanically and/or biologically occlude the target vessel, either temporarily or permanently. This definition excludes vessel-blocking agents or devices such as balloons and coils, which are positioned at the target site, as opposed to released in the bloodstream. Vascular embolisation agents are available as solids, liquids and suspensions. Careful selection of the agent based on the size and calibre of the target vessel ensures that the occlusion is confined to the desired site. In this review, we discuss the 2 main categories of embolisation agents: particles (either non-spherical or microspherical), which are the most widely used; and liquids (glues, gels, sclerosing agents and viscous emulsions). For each agent, we review the characteristics, mechanisms of action, main indications and modalities of use, advantages and drawbacks. The use of embolisation in clinical practice requires a thorough understanding of the behaviour (rheology and vascular topology) and biocompatibility of each agent. To improve the accuracy of targeting, we need new, more sophisticated, bioactive agents, which are being developed.

Refractory bleeding from gastroduodenal ulcers: arterial embolization in high-operative-risk patients.

Goals and Background We evaluated the efficacy and medium-term outcomes of transcatheter embolization to control massive bleeding from gastroduodenal ulcers after failed endoscopic treatment in high-operative-risk patients. Study Retrospective study of 35 consecutive emergency embolization procedures in hemodynamically unstable patients (24 men, 11 women, mean age 71±11.6 y) referred from 1999 to 2006 for selective angiography after failed endoscopic treatment. Mean follow-up was 27 months. Results Endovascular treatment was feasible in 33 patients and consistently stopped the bleeding. “Sandwich” coiling of the gastroduodenal artery was performed in 11 patients and superselective occlusion of the terminal feeding artery with glue, coils, or gelatine particles in 22 patients. Early rebleeding occurred in 6 patients and was managed successfully using endoscopy (n=2), reembolization (n=1), or surgery (n=3). No major complications related to catheterization occurred. Seven patients died within 30 days of embolization and 3 died later during the follow-up, but none of the deaths were due to rebleeding. No late bleeding recurrences were reported. Conclusions Selective angiographic embolization is safe and effective for controlling life-threatening bleeding from gastroduodenal ulcers, usually obviating the need for emergency surgery in critically ill patients, whose immediate survival depends on their underlying conditions.

MRI for evaluating Congenital bile duct abnormalities

Congenital bile duct diseases consist of ductal plate development abnormalities and are genetically determined. These biliary abnormalities are encountered mainly in congenital fibrocystic diseases, represented by congenital hepatic fibrosis and different forms of Caroli disease. On the other hand, polycystic hepatic diseases also present cystic abnormalities, which could be confused with biliary dilatations, especially in the perihilar area. Further, intricate forms between Caroli and polycystic hepatic diseases are possible. In congenital bile duct paucity, which is extremely rare, the biliary tree, located on the opposite, is not visible. MRI modalities for the analysis of the biliary tree are mainly represented by T2-weighted sequence, also known as MR cholangiography (MRCP), and T1 gadolinium-enhanced sequences. Familiarity with the most common appearances of congenital bile duct dilations, its variants, and related complex diseases facilitates accurate diagnosis and allows and helps avoid misinterpretation.

Caroli's disease: magnetic resonance imaging features

Abstract. Our objective was to describe the main aspects of MR imaging in Carolis disease. Magnetic resonance cholangiography with a dynamic contrast-enhanced study was performed in nine patients with Carolis disease. Bile duct abnormalities, lithiasis, dot signs, hepatic enhancement, renal abnormalities, and evidence of portal hypertension were evaluated. Three MR imaging patterns of Carolis disease were found. In all but two patients, MR imaging findings were sufficient to confirm the diagnosis. Moreover, MR imaging provided information about the severity, location, and extent of liver involvement. This information was useful in planning the best therapeutic strategy. Magnetic resonance cholangiography with a dynamic contrast-enhanced study is a good screening tool for Carolis disease. Direct cholangiography should be reserved for confirming doubtful cases.

Arterial embolization for massive hematuria following transurethral prostatectomy.

The management of significant hematuria following transurethral prostatectomy is most frequently surgical. We report on a patient who benefited from arteriography with arterial embolization for severe hematuria following transurethral prostatectomy. This method is an interesting alternative to surgical intervention. CASE REPORT A 66-year-old man presented with incapacitating dysuria due to benign prostatic hyperplasia. -Blockers had had no effect on the symptoms. Rectal examination revealed a soft and regular prostate. Prostate specific antigen (PSA) was 1.1 ng./ml. (normal less than 4). Ultrasound showed a trabeculated bladder without upper tract dilatation, with a post-void residual urine volume of 100 ml. Prostatic volume was estimated at 30 gm. The patient underwent transurethral prostatectomy, during which 25 gm. prostatic tissue was resected. No gross bleeding or perforation of the prostatic capsule was noted during surgery. Postoperative course was uneventful with normal voiding following catheter ablation. At 25 days postoperatively the patient was hospitalized for macroscopic hematuria. Irrigation through the bladder catheter was initially successful. However, 4 days later massive hematuria recurred, with red blood draining through the catheter until hemodynamic compromise necessitated a transfusion. Cystoscopy was impossible due to the significant bleeding. Emergent arteriography demonstrated active bleeding through the prostatic branch of the left hypogastric artery. Superselective arteriography revealed bleeding from a capsular artery (fig. 1). This artery was embolized and the bleeding stopped (fig. 2). Post-arteriography followup was uncomplicated. Bladder catheter was removed on day 2 and the patient was discharged home the following day. He was seen again at 5 weeks and 1 year postoperatively, at which time he was voiding comfortably without macroscopic hematuria.