René Müller-Wille

Assessment of Clinical Signs of Liver Cirrhosis Using T1 Mapping on Gd-EOB-DTPA-Enhanced 3T MRI

Objectives To assess the differences between normal and cirrhotic livers by means of T1 mapping of liver parenchyma on gadoxetic acid (Gd-EOB-DTPA)-enhanced 3 Tesla (3T) MR imaging (MRI). Methods 162 patients with normal (n = 96) and cirrhotic livers (n = 66; Child-Pugh class A, n = 30; B, n = 28; C, n = 8) underwent Gd-EOB-DTPA-enhanced 3T MRI. To obtain T1 maps, two TurboFLASH sequences (TI = 400 ms and 1000 ms) before and 20 min after Gd-EOB-DTPA administration were acquired. T1 relaxation times of the liver and the reduction rate between pre- and post-contrast enhancement images were measured. Results The T1 relaxation times for Gd-EOB-DTPA-enhanced MRI showed significant differences between patients with normal liver function and patients with Child-Pugh class A, B, and C (p < 0.001). The T1 relaxation times showed a constant significant increase from Child-Pugh class A up to class C (Child-Pugh class A, 335 ms ± 80 ms; B, 431 ms ± 75 ms; C, 557 ms ± 99 ms; Child-Pugh A to B, p < 0.001; Child-Pugh A to C, p < 0.001; Child-Pugh B to C, p < 0.001) and a constant decrease of the reduction rate of T1 relaxation times (Child-Pugh class A, 57.1% ± 8.8%; B, 44.3% ± 10.2%, C, 29.9% ± 6.9%; Child-Pugh A to B, p < 0.001; Child-Pugh A to C,p < 0.001; Child-Pugh B to C, p < 0.001). Conclusion Gd-EOB-DTPA-enhanced T1 mapping of the liver parenchyma may present a useful method for determining severity of liver cirrhosis.

Impact of liver cirrhosis on liver enhancement at Gd-EOB-DTPA enhanced MRI at 3 Tesla

PURPOSE The purpose of this study was to assess differences in enhancement effects of liver parenchyma between normal and cirrhotic livers on dynamic, Gd-EOB-DTPA enhanced MRI at 3T. MATERIALS AND METHODS 93 patients with normal (n=54) and cirrhotic liver (n=39; Child-Pugh class A, n=18; B, n=16; C, n=5) underwent contrast-enhanced MRI with liver specific contrast media at 3T. T1-weighted volume interpolated breath hold examination (VIBE) sequences with fat suppression were acquired before contrast injection, in the arterial phase (AP), in the late arterial phase (LAP), in the portal venous phase (PVP), and in the hepatobiliary phase (HBP) after 20 min. The relative enhancement (RE) of the signal intensity of the liver parenchyma was calculated for all phases. RESULTS Mean RE was significantly different among all evaluated groups in the hepatobiliary phase and with increasing severity of liver cirrhosis, a decreasing, but still significant reduction of RE could be shown. Phase depending changes of RE for each group were observed. In case of non-cirrhotic liver or Child-Pugh Score A cirrhosis mean RE showed a significant increase between AP, LAP, PVP and HBP. For Child-Pugh B+C cirrhosis RE increased until PVP, however, there was no change in case of B cirrhosis (p=0.501) and significantly reduced in case of C cirrhosis (p=0.043) during HBP. CONCLUSION RE of liver parenchyma is negatively affected by increased severity of liver cirrhosis, therefore diagnostic value of HBP could be limited in case of Child Pugh B+C cirrhosis.

Dynamic magnetic resonance defecography in 10 asymptomatic volunteers

AIM Evaluation of the wide range of normal findings in asymptomatic women undergoing dynamic magnetic resonance (MR) defecography. METHODS MR defecography of 10 healthy female volunteers (median age: 31 years) without previous pregnancies or history of surgery were evaluated. The rectum was filled with 180 mL gadolinium ultrasound gel mixture. MR defecography was performed in the supine position. The pelvic floor was visualized with a dynamic T2-weighted sagittal plane where all relevant pelvic floor organs were acquired during defecation. The volunteers were instructed to relax and then to perform straining maneuvers to empty the rectum. The pubococcygeal line (PCGL) was used as the line of reference. The movement of pelvic floor organs was measured as the vertical distance to this reference line. Data were recorded in the resting position as well as during the defecation process with maximal straining. Examinations were performed and evaluated by two experienced abdominal radiologists without knowledge of patient history. RESULTS Average position of the anorectal junction was located at -5.3 mm at rest and -29.9 mm during straining. The anorectal angle widened significantly from 93° at rest to 109° during defecation. A rectocele was diagnosed in eight out of 10 volunteers showing an average diameter of 25.9 mm. The bladder base was located at a position of +23 mm at rest and descended to -8.1 mm during defecation in relation to the PCGL. The bladder base moved below the PCGL in six out of 10 volunteers, which was formally defined as a cystocele. The uterocervical junction was located at an average level of +43.1 mm at rest and at +7.9 mm during straining. The uterocervical junction of three volunteers fell below the PCGL; described formally as uterocervical prolapse. CONCLUSION Based on the range of standard values in asymptomatic volunteers, MR defecography values for pathological changes have to be re-evaluated.

Added value of Gd-EOB-DTPA-enhanced Hepatobiliary phase MR imaging in evaluation of focal solid hepatic lesions

BackgroundCorrect characterization of focal solid hepatic lesions has always been a challenge and is of great diagnostic and therapeutic relevance. The purpose of this study was to determine the added value of hepatobiliary phase images in Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) for differentiating focal solid hepatic lesions.MethodsIn this retrospective trial 84 consecutive patients underwent Gd-EOB-DTPA-enhanced MR examinations. MRI was conducted for 64 patients with malignant focal hepatic lesions (34 hepatocellular carcinoma (HCC), 30 metastases) and for 20 patients with benign hepatic lesions (14 focal nodular hyperplasia (FNH), 3 adenoma, 3 hemangioma). Five radiologists independently reviewed three sets of MR images by means of a 5-point confidence scale from score 1 (definitely benign) to score 5 (definitely malignant): set 1: unenhanced images; set 2: unenhanced and Gd-EOB-DTPA-enhanced dynamic images; set 3: hepatobiliary phase images in addition to set 2. Accuracy was assessed by the alternative free-response receiver operating characteristic curve (Az) and the index of diagnostic performance was calculated.ResultsDiagnostic accuracy was significantly improved by the addition of Gd-EOB-DTPA-enhanced dynamic images: Az in set 1 was 0.708 and 0.833 in set 2 (P = 0.0002). The addition of hepatobiliary phase images increased the Az value to 0.941 in set 3 (set 3 vs set 2, P < 0.0001; set 3 vs set 1, P < 0.0001). The index of diagnostic performance was lowest in set 1 (45%), improved in set 2 (71%), and highest in set 3 (94%).ConclusionsHepatobiliary phase images obtained after Gd-EOB-DTPA-enhanced dynamic MRI improve the differentiation of focal solid hepatic lesions.

Multidetector computed tomography for detection and characterization of pulmonary hypertension in consideration of WHO classification.

Objective We evaluated the reliability of various multidetector computed tomography (MDCT) parameters for diagnosis and severity assessment of pulmonary hypertension (PH) with consideration of World Health Organization (WHO) classification. Methods A total of 172 patients were included in this retrospective study. One hundred fourteen patients had a diagnosis of PH (mean pulmonary artery pressure ≥25 mm Hg), and 58 patients without PH (mean pulmonary artery pressure <20 mm Hg) served as control subjects. The patients with PH were grouped according to the WHO classification based on PH etiology. Results The patients with PH had significantly greater main, left, and right pulmonary artery diameters than the control subjects (P < 0.001). No significant differences within the PH subgroups were found. Receiver operating characteristic analysis showed reasonable sensitivity and specificity for selected MDCT parameters. The severity of PH did not correlate with MDCT parameters. Conclusions Easy-to-determine MDCT parameters allow detection of PH independent of the WHO group. In patients with dilated aorta, the vertebra can be an alternative internal standard. Severity of PH cannot be estimated by MDCT parameters.

Onyx (Ethylen-Vinyl-Alkohol-Kopolymer) – Ein neuer Anwendungsbereich in der endovaskulären Behandlung akuter peripherer Blutungen

PURPOSE The purpose of our retrospective study was to determine the feasibility and efficacy of the endovascular embolization of peripheral acute arterial hemorrhage using Onyx. MATERIALS AND METHODS Between October 2003 and February 2007, 14 patients with acute arterial bleeding underwent percutaneous arterial embolization using Onyx. Bleeding was caused by iatrogenic vessel injury (6 patients), malignancy/inflammation (5 patients) and trauma (3 patients). Hematomas were located in the pelvis (5 patients), followed by liver (3 patients), retroperitoneal space (2 patients), thorax (2 patients), pancreas (1 patient), and thigh (1 patient). The number of embolized arteries, the volume and viscosity of embolic agent (Onyx), the number of additionally used coils, the embolization time, and the technical and clinical outcome were documented. Procedure-related complications, recurrent bleeding during hospital stay and outcome were recorded. RESULTS In 14 patients selective endovascular embolization of 15 arteries was performed. The average volume of injected Onyx was 1.3 +/- 0.8 ml. In 6 cases (42.9%) Onyx was used in conjunction with coils. The average time between the correct placement of microcatheter and complete embolization was 24.9 +/- 12.6 minutes. In 13 of 14 patients (92.8%), embolization was technically successful. In one case, procedure-related complications occurred and embolization was performed in a second session a day later. After technically successful embolization, no recurrent bleeding occurred during hospitalization. Out of 14 patients, six (42.9%) died 1 - 38 days after technically successful embolization due to multiple organ failure (2 patients), hypoxic brain injury (2 patients), septic shock (1 patient) or malignancy-associated death (1 patient). CONCLUSION We conclude that transcatheter embolization with the new liquid embolic agent Onyx is technically feasible and effective in patients with acute arterial hemorrhage.

CT Features of Early Type II Endoleaks after Endovascular Repair of Abdominal Aortic Aneurysms Help Predict Aneurysm Sac Enlargement

PURPOSE To determine computed tomographic (CT) features of early type II endoleaks associated with aneurysm sac enlargement after endovascular aortic aneurysm repair (EVAR) of abdominal aortic aneurysm. MATERIALS AND METHODS Institutional review board approval was not required for this retrospective study. The authors reviewed imaging and clinical data from 56 patients (seven women, 49 men; mean age ± standard deviation, 71 years ± 7.9; age range, 52-85 years) with early type II endoleak who had undergone EVAR between December 2002 and December 2011 and who had been followed up with imaging and clinical evaluation for at least 6 months. The number and diameter of all feeding and/or draining arteries were measured, and endoleaks were classified according to their sources into simple inferior mesenteric artery (IMA), simple lumbar artery (LA), complex LA, and complex IMA-LA type II endoleaks. Volume and attenuation of the nidus were measured. Aneurysm enlargement was defined as an increase in the aneurysm volume of more than 5% during follow-up. Simple and multivariate logistic regression analyses were performed to identify independent clinical and imaging variables associated with aneurysm enlargement. RESULTS Twenty-three of the 56 patients (41%) showed aneurysm sac enlargement during follow-up (mean follow-up, 3.0 years ± 2.0). With the multivariate model, the variables that showed the strongest indicators for aneurysm sac enlargement were complex IMA-LA type II endoleak (odds ratio [OR] = 10.29, P = .004) and the diameter of the largest feeding and/or draining artery (OR = 4.55, P = .013). Patients without complex IMA-LA type II endoleak in whom the largest feeding and/or draining artery was larger than 3.8 mm and patients with a complex IMA-LA type II endoleak in whom the largest feeding and/or draining artery was larger than 2.2 mm were at high risk for aneurysm sac enlargement. CONCLUSION The strongest indicators for aneurysm sac enlargement are complex IMA-LA type II endoleak and the diameter of the largest feeding and/or draining artery.

Irreversible Electroporation of Malignant Hepatic Tumors - Alterations in Venous Structures at Subacute Follow-Up and Evolution at Mid-Term Follow-Up

Purpose To evaluate risk factors associated with alterations in venous structures adjacent to an ablation zone after percutaneous irreversible electroporation (IRE) of hepatic malignancies at subacute follow-up (1 to 3 days after IRE) and to describe evolution of these alterations at mid-term follow-up. Materials and Methods 43 patients (men/women, 32/11; mean age, 60.3 years) were identified in whom venous structures were located within a perimeter of 1.0 cm of the ablation zone at subacute follow-up after IRE of 84 hepatic lesions (primary/secondary hepatic tumors, 31/53). These vessels were retrospectively evaluated by means of pre-interventional and post-interventional contrast-enhanced magnetic resonance imaging or computed tomography or both. Any vascular changes in flow, patency, and diameter were documented. Correlations between vascular change (yes/no) and characteristics of patients, lesions, and ablation procedures were assessed by generalized linear models. Results 191 venous structures were located within a perimeter of 1.0 cm of the ablation zone: 55 (29%) were encased by the ablation zone, 78 (41%) abutted the ablation zone, and 58 (30%) were located between 0.1 and 1.0 cm from the border of the ablation zone. At subacute follow-up, vascular changes were found in 19 of the 191 vessels (9.9%), with partial portal vein thrombosis in 2, complete portal vein thrombosis in 3, and lumen narrowing in 14 of 19. At follow-up of patients with subacute vessel alterations (mean, 5.7 months; range, 0 to 14 months) thrombosis had resolved in 2 of 5 cases; vessel narrowing had completely resolved in 8 of 14 cases, and partly resolved in 1 of 14 cases. The encasement of a vessel by ablation zone (OR = 6.36, p<0.001), ablation zone being adjacent to a portal vein (OR = 8.94, p<0.001), and the usage of more than 3 IRE probes (OR = 3.60, p = 0.035) were independently associated with post-IRE vessel alterations. Conclusion Venous structures located in close proximity to an IRE ablation zone remain largely unaffected by this procedure, and thrombosis is rare.

Inferior Mesenteric Arterial Type II Endoleaks after Endovascular Repair of Abdominal Aortic Aneurysm: Are They Predictable?

PURPOSE To evaluate the association of inferior mesenteric arterial (IMA) type II endoleaks in patients undergoing endovascular aortic aneurysm repair (EVAR) for infrarenal abdominal aortic aneurysm with several morphologic parameters. MATERIALS AND METHODS Approval of the institutional ethical review committee was not required. This was a retrospective review of 322 computed tomographic angiographic studies that were performed in patients before they underwent elective EVAR for infrarenal abdominal aortic aneurysm. Morphologic parameters evaluated were IMA patency, origin of the IMA in relation to the aneurysm sac, diameter of the IMA, the cross-sectional area of the contrast material-enhanced aortic lumen at the level of the IMA ostium, and the number of additional patent aortic side branches from the aneurysm sac. The association of IMA type II endoleaks with each variable was analyzed by using univariate and multivariate logistic regression models. RESULTS The diameter of the IMA did not influence the development of IMA type II endoleaks (P = .51). The incidence of these endoleaks was significantly higher in patients with greater cross-sectional area of the aortic lumen at the IMA ostium (P < .001). Patients with an IMA type II endoleak had significantly more patent aortic side branches before EVAR than did patients without an endoleak (3.6 ± 1.7 vs 2.2 ± 1.4; P < .001). According to the final logistic regression model that included cross-sectional area of the aortic lumen at the IMA and the number of aortic side branches as independent predictors, risk for IMA type II endoleaks was determined with a sensitivity of 78% (39 of 50) and a specificity of 79% (92 of 116). CONCLUSION Cross-sectional area of the contrast-enhanced aortic lumen at the level of the IMA ostium and the number of additional patent aortic side branches are associated with the development of IMA type II endoleaks.

Analysis of thrombotic deposits in extracorporeal membrane oxygenators by multidetector computed tomography.

Oxygenator thrombosis is a serious complication in extracorporeal membrane oxygenation (ECMO) and may necessitate a system exchange. Coagulation and fibrinolysis parameters, flow dynamics, and gas transfer performance are currently used to evaluate the degree of oxygenator thrombosis, but there is no technical approach for direct visualization and quantification of thrombotic deposits within the membrane oxygenator (MO). We used multidetector computed tomography (MDCT) with three-dimensional postprocessing to assess the incidence of oxygenator thrombosis, to quantify thrombus extent, and to localize clot distribution. Twenty heparin-coated MOs after successful weaning were analyzed. Mean ECMO support time was 7 ± 4 days, mean activated partial thromboplastin time (aPTT) during ECMO was 59 ± 20 seconds. Thrombotic deposits were detected in all MOs. The mean clot volume was 51.7 ± 22.3 cm3. All thrombotic deposits were located in the venous, i.e., inlet part of the device, without apparent evidence of embolization in patients. There was no correlation between clot volume and ECMO support time or aPTT. Clot formation within the MO is a common finding in ECMO despite adequate systemic anticoagulation. The clinical significance of thrombus formation and its influence on gas exchange capacity and hemostatic complications have to be addressed in further studies.