Wigbert S. Rau

Measurement of single-kidney glomerular filtration rate using a contrast-enhanced dynamic gradient-echo sequence and the Rutland-Patlak plot technique.

To determine the accuracy of single‐kidney glomerular filtration rate (GFR) determination using contrast‐enhanced dynamic magnetic resonance imaging (MRI) and the Rutland‐Patlak plot technique.

Correlation of Vasa Vasorum Neovascularization and Plaque Progression in Aortas of Apolipoprotein E−/−/Low-Density Lipoprotein−/− Double Knockout Mice

Objective—We hypothesized that apolipoprotein E (apoE)−/−/low-density lipoprotein (LDL)−/− double knockout mice might develop vasa vasorum (VV) in association with advanced lesion formation. Methods and Results—Aortas from apoE−/−/LDL−/− mice aged 16, 18, 20, or 80 weeks were infused in situ with Microfil, harvested, and scanned with micro-computed tomography (CT). We characterized plaque volume and CT “density” as well as VV luminal volume along the aorta using Analyze 6.0 software. Results were complemented by a detailed histological plaque classification according to American Heart Association guidelines. From 16 to 80 weeks, plaque volume and VV opacified lumen volume increased with age (P<0.001). The 3-dimensional micro-CT images of arterial and venous VV trees allowed perfusion territories to be delineated. The spatial location and magnitude of VV density and adventitial inflammation were strongly correlated in advanced atherosclerotic lesions (r=0.91) and identified as an independent correlate to advanced lesions. At age 80 weeks, VV luminal volume was increased 20-fold compared with animals at age 16 weeks (P<0.001). Micro-CT showed that adventitial VV communicate with intraplaque microvessels. Conclusion—Our results show that apoE−/−/LDL−/− double knockout mice develop VV and advanced atheromas along the aorta. Lesion volume was closely associated with amount of neovascularization in advanced atheromas.

Glomerular filtration rate measured using the Patlak plot technique and contrast-enhanced dynamic MRI with different amounts of gadolinium-DTPA.

We determined the optimum gadolinium (Gd)‐DTPA dose and time window for calculating the glomerular filtration rate (GFR) using contrast‐enhanced (CE) dynamic MRI and the Patlak plot technique. Twelve adult volunteers with healthy kidneys were included in the study. As a reference method the GFR was measured by iopromide plasma clearance. A three‐dimensional gradient‐echo (GRE) sequence with a flip angle of 50° was used for MRI. Signal was measured using a body surface coil with four elements. Each volunteer was examined on four days using 2 mL, 4 mL, 8 mL, or 16 mL of Gd‐DTPA 0.5 mmol/mL dissolved with sodium chloride (NaCl) 0.9% to a total of 60 mL. The injection rate was 1 mL/second. A Patlak plot was calculated from the kidney and aorta signals. The mean reference GFR was 133 mL/min (min‐max, 116–153 mL/min). The best correlation of GFR calculated from MRI data compared to the reference method was found in a time window 30–90 seconds after aortic signal rise using 16 mL Gd‐DTPA. Pearsons correlation coefficient was r = 0.83, and the standard deviation (SD) from the line of regression was 10.5 mL/minute. We found a significantly lower average GFR(MR) using 16 mL Gd‐DTPA compared to 4 mL and 2 mL in the late time window 60–120 seconds post aortic rise. A dose of 16 mL Gd‐DTPA was optimal for measuring GFR using dynamic MRI and the Patlak plot technique. The slope should be measured in a time window of 30–90 seconds post aortic rise. J. Magn. Reson. Imaging 2005.

Effectiveness of therapeutic lymphography on lymphatic leakage

Background The number of conventional lymphographies has declined markedly since the introduction of cross-sectional imaging techniques. Nevertheless, lymphography has a high potential as a reliable method to visualize and directly occlude lymphatic leaks. When used as a distinct radiological procedure with the intention to treat, this application can be described as therapeutic lymphography. Purpose To investigate if therapeutic lymphography is a reliable method to treat lymphatic leakage when conservative treatment fails and to investigate which parameters influence the success rate. Material and Methods Between August 1995 and January 2008, 50 patients with lymphatic leakage in form of chylothorax, chylous ascites, lymphocele, and lymphatic fistulas underwent conventional therapeutic lymphography after failure of conservative therapy. Of these 50 patients, seven could not be statistically evaluated in our retrospective study: one patient died of cancer 1 day after lymphography, and six were excluded due to various technical problems. The remaining 43 patients were evaluated. Therapeutic success was evaluated and correlated to the volume of lymphatic leakage (more or less than 500 mL/day), as assessed by drainage. Results In nearly 79% of patients, the location of the leak could be detected, and surgical intervention could be planned when therapeutic lymphography failed. Due to the irrigating effect of the contrast medium (lipiodol), the lymphatic leak could be completely occluded in 70% of patients when the lymphatic drainage volume was less than 500 mL/day. Even when lymphatic drainage was higher than 500mL/day, therapeutic lymphography was still successful in 35% of the patients. The overall success rate in patients with failed conservative treatment was 51%. Success did not depend on other factors such as age and sex, cause of lymph duct damage, or time elapsed between lymphatic injury and intervention. Conclusion Therapeutic lymphography is an effective method in the treatment of lymphatic leakage when conservative therapy fails. The volume of lymphatic drainage per day is a significant predictor of the therapeutical success rate.

Percutaneous transhepatic catheterization of the portal vein: A combined CT- and fluoroscopy-guided technique.

Combined CT- and fluoroscopy-guided transhepatic portal vein catheterization was performed in 44 patients selected for pancreatic islet cell transplantation. The method allowed catheterization with a single puncture attempt in 39 patients. In four patients two attempts and in one patient four attempts were necessary. One minor hematoma of the liver capsule occurred that required no further treatment. Compared with other methods the average number of puncture attempts was reduced.

The role of magnetic resonance imaging and scintigraphy in the diagnosis of pathologic changes of the mandible after radiation therapy

A prospective study of 85 patients with oral cancer, treated with high-dose radiation therapy, was performed to assess the value of magnetic resonance imaging (MRI) and scintigraphy for diagnosis of pathologic changes in the mandible. During postradiotherapeutic monitoring, radiation osteomyelitis occurred in 12 cases, tumor recurrences infiltrating the mandible in five cases, and progressive periodontal disease in nine cases. MRI permitted early diagnosis of radiation osteomyelitis in 11 out of 12 cases; only two cases were false positive. In scintigraphy with 99mTc-HDP, all alterations of the mandible, such as osteoradionecrosis, tumor infiltration, and periodontitis, showed a high uptake, resulting in a sensitivity of up to 100%, but a low specificity of 57%. Scintigraphy permitted assessment of the extension and location of the lesions. Both methods were superior to conventional radiography and clinical examination and should be integrated into a comprehensive follow-up program after radiation therapy.

Tracheal rupture caused by blunt chest trauma: radiological and clinical features

Abstract. The aim of this study was to assess radiomorphologic and clinical features of tracheal rupture due to blunt chest trauma. From 1992 until 1998 the radiomorphologic and clinical key findings of all consecutive tracheal ruptures were retrospectively analyzed. The study included ten patients (7 men and 3 women; mean age 35 years); all had pneumothoraces which were persistent despite suction drainage. Seven patients developed a pneumomediastinum as well as a subcutaneous emphysema on conventional chest X-rays. In five patients, one major hint leading to the diagnosis was a cervical emphysema, discovered on the lateral cervical spine view. Contrast-media-enhanced thoracic CT was obtained in all ten cases and showed additional injuries (atelectasis n = 5; lung contusion n = 4; lung laceration n = 2; hematothorax n = 2 and hematomediastinum n = 4). The definite diagnosis of tracheal rupture was made by bronchoscopy, which was obtained in all patients. Tracheal rupture due to blunt chest trauma occurs rarely. Key findings were all provided by conventional chest X-ray. Tracheal rupture is suspected in front of a pneumothorax, a pneumomediastinum, or a subcutaneous emphysema on lateral cervical spine and chest films. Routine thoracic CT could also demonstrate these findings but could not confirm the definite diagnosis of an tracheal rupture except in one case; in the other 9 cases this was done by bronchoscopy. Thus, bronchoscopy should be mandatory in all suspicious cases of tracheal rupture and remains the gold standard.

Hepatobiliary and Pancreatic MRI and MRCP Findings in Patients with HIV Infection

OBJECTIVE The purpose of this article is to describe the spectrum of MRI and MR cholangiopancreatography (MRCP) findings of hepatic, pancreatic, and biliary manifestations in patients with HIV infection. CONCLUSION The spectrum of MRI and MRCP findings in HIV-infected patients includes acute or chronic hepatitis (or both), pancreatitis, cholangitis, acalculous cholecystitis, and biliary strictures that may resemble primary sclerosing cholangitis. The presence of segmental extrahepatic biliary strictures is characteristic of AIDS cholangiopathy.

MRI and MRCP Findings of the Pancreas in Patients With Diabetes Mellitus : Compared Analysis With Pancreatic Exocrine Function Determined by Fecal Elastase 1

Goals To review magnetic resonance imaging and magnetic resonance cholangiopancreatography (MRCP) findings in patients with diabetes mellitus (DM), with pancreatic exocrine insufficiency, and with combined pancreatic exocrine insufficiency and DM. Study MRI/MRCP findings of 82 consecutive patients with DM (n=28), pancreatic exocrine insufficiency (n=25), and combination of both (n=29) were evaluated and compared with MRI/MRCP findings of 21 healthy volunteers with normal pancreatic exocrine function. Pancreatic exocrine function was determined by fecal elastase 1. MRCP images were evaluated according to the Cambridge classification. MRI of the pancreas was assessed for pancreatic size, signal intensity ratio (SIR), and arterial/venous enhancement ratio (A/V). Results On MRI, significant difference was present in terms of mean values of pancreatic size (P<0.0001), A/V (P<0.02), and SIR (P<0.005) between the control group and groups of patients with DM, pancreatic exocrine insufficiency, and combined DM and pancreatic exocrine insufficiency. No significant difference was observed between groups of patients with DM and pancreatic exocrine function alone in terms of pancreatic size, A/V, and SIR. Chronic pancreatitis MRCP findings were present with increasing frequency in groups of DM, pancreatic exocrine insufficiency, and combination of both. Conclusions MRI/MRCP findings suggesting chronic pancreatitis may exist in patients with DM comparable to patients with pancreatic exocrine insufficiency. The frequency and severity of MRI/MRCP findings increase when the patients have combined DM and pancreatic exocrine insufficiency.

Degenerative joint disease on MRI and physical activity: a clinical study of the knee joint in 320 patients

Abstract. We examined 320 patients with MRI and arthroscopy after an acute trauma to evaluate MRI in diagnosis of degenerative joint disease of the knee in relation to sports activity and clinical data. Lesions of cartilage and menisci on MRI were registered by two radiologists in consensus without knowledge of arthroscopy. Arthroscopy demonstrated grade-1 to grade-4 lesions of cartilage on 729 of 1920 joint surfaces of 320 knees, and MRI diagnosed 14 % of grade-1, 32 % of grade-2, 94 % of grade-3, and 100 % of grade-4 lesions. Arthroscopy explored 1280 meniscal areas and showed degenerations in 10 %, tears in 11.4 %, and complex lesions in 9.2 %. Magnetic resonance imaging was in agreement with arthroscopy in 81 % showing more degenerations but less tears of menisci than arthroscopy. Using a global system for grading the total damage of the knee joint into none, mild, moderate, or severe changes, agreement between arthroscopy and MRI was found in 82 %. Magnetic resonance imaging and arthroscopy showed coherently that degree of degenerative joint changes was significantly correlated to patient age or previous knee trauma. Patients over 40 years had moderate to severe changes on MRI in 45 % and patients under 30 years in only 22 %. Knee joints with a history of trauma without complete structural or functional reconstitution showed marked changes on MRI in 57 %, whereas stable joints without such alterations had degenerative changes in only 26 %. There was no correlation of degenerative disease to gender, weight, type, frequency, and intensity of sports activity. Therefore, MRI is an effective non-invasive imaging method for exact localization and quantification of chronic joint changes of cartilage and menisci that recommends MRI for monitoring in sports medicine.