Biomedical subjects

Wigbert S Rau

Publications and source records attributed to Wigbert S Rau.

9 recordsLinked to original sources

PubMed2006

Split renal function measured by triphasic helical CT.

PURPOSE: To present a method for calculating split renal function solely from routine triphasic helical computed tomography (CT). SUBJECTS AND METHODS: We retrospectively included 26 adult patients who received renal scintigraphy and triphasic CT within 4 weeks in the years 2003 and 2004. All scans were performed using a standard abdominal protocol. Split renal function was calculated as relative single-kidney glomerular filtration rate (GFR) using a simplified "two-point Patlak plot" technique. As a reference method, split renal function was determined from renal scintigraphy using the standard technique. RESULTS: Linear correlation between the two methods was r=0.91, split renal function (CT)=0.0266+0.9573 x split renal function (scintigraphy). CONCLUSION: Split renal function can be measured accurately by minimally extended triphasic CT.

Adult↗

PubMed2005

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. CONCLUSIONS: 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.

Animals↗

PubMed2005

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 degrees 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. Pearson's 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.

Adult↗

PubMed2005

A 22-year-old woman with lower limb arteriopathy. Buerger's disease, or methamphetamine- or cannabis-induced arteritis?

This case report describes a 22-year-old woman with severe arterial ischemia leading to claudication and ulceration of the feet, presumably due to long-term abuse of amphetamine derivates, such as "speed" or "ecstasy," and cannabis. Known causes for peripheral occlusive disease, such as atherosclerosis, vasculitis, or collagen vascular disease, were excluded. Laboratory test results did not show evidence of risk factors for thromboembolic diseases. Conventional angiography and magnetic resonance-angiography showed occlusions of medium- and small-sized arteries of both calves and feet. In the past, vasculitis-like arteriopathy was attributed to the abuse of amphetamines as well as of cannabis. However, amphetamines have been reported to be associated with necrotizing vasculitis mainly of cerebral arteries. Therefore, the abuse of methamphetamine or "ecstasy" also appears to play a role in the development of peripheral arterial occlusions and seems to have broad similarities with Buerger's disease.

Adult↗

PubMed2003

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

PURPOSE: 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. MATERIALS AND METHODS: Twenty-eight adult patients were included. As reference method, the GFR was measured by plasma clearance using a small bolus injection of iopromide. A three-dimensional gradient-echo (GRE) sequence with a flip angle of 50 degrees was used for MRI; this showed a good linear relationship between gadolinium (Gd)-DTPA concentration and signal change when measured up to a Gd-DTPA concentration of 10 mmol/liter. A slab containing both kidneys and the abdominal aorta was measured 30 times in approximately 3.5 minutes. During this measurement, 15 mL of Gd-DTPA, 0.5 mol/liter diluted to a volume of 60 mL, was injected over 60 seconds. A Rutland-Patlak plot was calculated from the signal changes in the aorta and the renal parenchyma. Single-kidney GFR was calculated for different time windows from the Rutland-Patlak plot slope. RESULTS: The best correlation compared to the reference method was found with the GFR calculated from the slope of the Rutland-Patlak plot 40-110 seconds postaortic rise. Pearson's correlation coefficient was r = 0.86, SD was 14.8 mL/minute. In many of the patients, a decrease of the renal signal was observed in the excretory phase, which was probably caused by very high Gd-DTPA concentrations in the collecting tubules. CONCLUSION: Single-kidney GFR can be calculated from dynamic contrast-enhanced MRI. We found a promising correlation of global GFR calculated by MRI compared to the reference method. In any future study, the amount of Gd-DTPA should by reduced to avoid artificial signal drop in the excretory phase induced by the T2* effect.

Adult↗

PubMed2002

Puncture of the popliteal artery using a Doppler-equipped (SMART) needle in transpopliteal interventions.

The puncture of the popliteal artery for percutaneous intervention is usually performed under fluoroscopic guidance or with the assistance of percutaneous ultrasound to avoid accidental arteriovenous fistulas. We present our experience in 119 cases with the use of a Doppler ultrasound equipped Seldinger needle (SMART needle) for the detection and puncture of the popliteal artery. In 119 interventions in 103 patients, the puncture of the popliteal artery was performed with the SMART needle. The puncture was successful in 94.1% (112 of 119) of cases. Six (5.2%) complications occurred during puncture: four hematomas (no therapy required) and two arteriovenous fistulas (treated by manual compression solely). The subsequent 112 interventions in 103 patients [98 percutaneous transluminal angioplasty (PTA), 8 PTA with stent implantations, 4 PTA with thrombolysis, 2 thrombolyses] were technically successful in 79.5% (89 of 112). The SMART-needle-guided popliteal puncture showed to be safe, fast, and easy to perform, which allowed the use of this technique by radiologists in training. The rates of success and complications are comparable to reported results for other visualization techniques, whereas time, effort, and training required are lower. This may contribute to a more widespread use of the transpopliteal access for interventions and therefore offers a therapeutic option in addition to vascular surgery.

Angioplasty, Balloon↗

PubMed2002

Lopromide one-sample clearance as a measure of glomerular filtration rate.

OBJECTIVE: The pharmacokinetics of iopromide were analysed using a two-compartment model. The optimal point of time for blood withdrawal for calculation of a one-sample clearance was determined. METHODS: Plasma concentration of iodine was measured up to 8 h postinjection (p.i.) in 62 adult patients who received 120 ml iopromide for computed tomography (CT). A two exponential function was fitted by a weighted least error square method. As reference method, clearance was calculated from this function and the injected amount of iodine. Empirical parameters for calculation of one-sample clearance were determined. This one-sample clearance was compared with one-sample clearance calculated according to formulas developed for Tc99m-DTPA by Jacobsson as well as a two sample method. RESULTS: Total distribution volume of iopromide was calculated as 0.242 Lkg(-1)+/- 5.9%. A high correlation of all one-sample method and the two-sample method with reference to clearance was found. Best estimation of iopromide plasma clearance was achieved by determining one-sample clearance 270 or 285 min p. i. with SD(y.x) of 5.8 ml min(-1). CONCLUSIONS: After administration of 120 ml iopromide, one-sample plasma clearance can be calculated with low estimation error taking one blood sample at an appropriate time point. Late phase pharmacokinetics of iopromide found in the present study showed to be virtually identical to results published for iohexol and Tc99m-DTPA.

Adult↗

PubMed2002

Contrast media clearance in a single kidney measured on multiphasic helical CT: results in 50 patients without acute renal disorder.

OBJECTIVE: Single kidney contrast media clearance was measured using multiphasic CT in patients without acute renal disorder. The aim of this study was to answer two questions. First, how accurate is CT in measuring contrast media clearance compared with plasma clearance? Second, is the accuracy of CT clearance measurements dependent on the timing of CT scans with respect to the contrast media injection? SUBJECTS AND METHODS: Fifty adult patients without acute renal disorder were included in this study. Each patient underwent CT for clinical indications. The CT protocol consisted of an unenhanced scan and three contrast-enhanced scans 45, 75, and 105 sec after starting an injection of 120 mL of iopromide using an injection rate of 3 mL/sec. All scans included both kidneys. As a reference, plasma clearance of contrast media was determined as a slope clearance by measuring iodine concentration in eight blood specimens up to 8 hr postinjection. RESULTS: CT clearance was calculated three times for each patient, including early CT clearance, 45-75 sec postinjection; late CT clearance, 75-105 sec postinjection; and overall CT clearance, 45-105 sec postinjection. An overall CT clearance yielded the best correlation with plasma clearance with a correlation coefficient of r = 0.84 and a regression line of y = 7.5 + 0.94x. The mean difference was -3 mL/min (95% confidence interval, -35 to 29 mL/min). CONCLUSION: CT clearance calculated from data acquired with a minimally modified diagnostic abdominal CT protocol was well correlated with the reference method in determining contrast media clearance for patients without acute renal disorders. The presented method can be used to calculate single kidney contrast media clearance in patients receiving contrast-enhanced abdominal CT for clinical indications.

Adult↗

PubMedDate not supplied

Informatics in radiology (infoRAD): new tools for computer assistance in thoracic CT. Part 1. Functional analysis of lungs, lung lobes, and bronchopulmonary segments.

Owing to the rapid development of scanner technology, thoracic computed tomography (CT) offers new possibilities but also faces enormous challenges with respect to the quality of computer-assisted diagnosis and therapy planning. In the framework of the Virtual Institute for Computer Assistance in Clinical Radiology cooperative research project, a prototypical software application was developed to assist the radiologist in functional analysis of thoracic CT data. By identifying the anatomic compartments of the lungs, the software application enables assessment of established functional CT parameters for each individual lung, pulmonary lobe, and pulmonary segment. Such region-based assessment allows a more localized diagnosis of lung diseases such as emphysema and more accurate estimation of regional lung function from CT data. With close cooperation between computer scientists and radiologists, the software application was tested and optimized to achieve a high degree of usability. Several clinical studies were carried out, the results of which indicated that the software application improves quantification in diagnosis, therapy planning, and therapy monitoring with respect to accuracy and time required.

Algorithms↗