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W S Rau

Publications and source records attributed to W S Rau.

At least 19 recordsLinked to original sources
PubMed2005

Quantification of in-stent restenosis parameters in rabbits by Micro-CT.

PURPOSE: The well-defined model of angioplasty and stent implantation in the rabbit aorta is useful in experimental studies of restenosis. This study was performed to evaluate the feasibility of Micro-CT for quantification of in-stent restenosis in a rabbit aortic in-stent-restenosis model. MATERIAL AND METHODS: To induce in-stent restenosis seven female New Zealand rabbits underwent balloon dilation and denudation prior to stenting the abdominal aorta. After six weeks on atherogenic diet, animals were killed and the aorta was perfused with contrast agent. Micro-CT morphometric analysis of balloon and stent injured arteries obtained by 700 transverse sections (voxel size 10 microm) was compared to conventional histological analysis. RESULTS: Intimal hyperplasia was present in stented and balloon injured arteries with a moderate intimal area assessed by Micro-CT and conventional histology (3.91 +/- 0.5 mm(2) vs. 4.18 +/- 0.42; r = 0.9). High significant correlations between Micro-CT image analysis and conventional histomorphometry were obtained for lesion size, size of media, size of lumen and stent area (r = 0.84 to 0.96). CONCLUSION: Micro-CT is feasible for quantitative information about restenosis following balloon angioplasty and stent implantation and has the potential to become a standard technique in many laboratories which will augment serial histology as the reference method for ex-vivo studies of restenosis.

Algorithms↗
PubMed2004

[Cardio-pulmonary vascular system. Three-dimensional quantitative evaluation by microcomputed tomography].

In recent years microcomputed tomography (microCT) has become more and more important in basic research. Now commercial microCT scanners are available. Thus, it is very likely that this new, accurate and promising method for three-dimensional and non-destructive quantitative evaluation of intact tissues including vessels will be applied more frequently. The review provides a survey of the basic technology of microCT and its current use for high resolution three-dimensional morphometric and functional analysis within the cardio-pulmonary vascular system.

Aorta, Thoracic↗
PubMed2004

[Micro-computed tomography of the vasculature in parenchymal organs and lung alveoli].

Micro-CT has become a powerful technique in non-destructive 3D imaging and morphometric analysis. First results were limited to the investigation of osteoporosis in cancellous bone. But the availability of systems with almost microscopic resolution and sufficient soft tissue contrast has opened up entirely new applications for laboratory investigation of blood vessels and soft tissues. This article gives an overview of micro-CT technology and the potential of three-dimensional imaging of the vessel wall and soft-tissue architecture imaging in different organs using different contrast perfusion and staining techniques. Micro-CT provides quantitative information on human plaque morphology equivalent to histomorphometric analysis. Based on differences in grey-scale attenuations, micro-CT also correctly identifies atherosclerotic lesions that are histologically classified as fibrous plaques, calcified lesions, fibroatheroma, and lipid rich lesions. Micro-CT is a promising method to visualize the architecture of the renal vasculature and, importantly, to separate cortex and medulla for the visualization of glomeruli and their afferent and efferent arterioles. Micro-CT can determine the vascular surface in a defined placental volume. Combining of micro-CT data and total placental volume enables an estimation of the approximate surface of the placental vasculature. The diameter of opacified vessels in the investigated samples ranged from 2 mm (chorion plate artery) to 14 micro m (smallest vessel diameter, terminal loop). Recognizing that lung parenchyma can only be visualized if the alveoli are completely expanded and the contrast of the thin alveolar walls is enhanced, we tested two preparation methods: (1) fixation of lung tissue with formalin vapour and staining with silver nitrate, and (2) intravenous injection of a barium sulfate-gelatine-thymol mixture in vivo in the anesthetized animal. We evaluated the ability of this mixture to enter the pulmonary microcirculation and the technical feasibility of micro-CT to assess lung micro-architecture.

Animals↗
PubMed2003

Measurement of glomerular filtration rate by low-dose iopromide plasma clearance.

PURPOSE: Glomerular filtration rate (GFR) can be measured by iopromide plasma clearance. As an injection of 120 ml nonionic contrast medium is expensive and especially in patients with nephropathy potentially nephrotoxic, we investigated whether iopromide plasma clearance could be measured using a tenth of that dose as 'low-dose' clearance. MATERIAL AND METHODS: Fifty adult patients scheduled for CT were recruited. Iopromide 300 mg I/ml was used for GFR measurement. Prior to CT, low-dose clearance was measured by injecting 12 ml iopromide per 75 kg b.w. At 3, 4 and 5 h after injection, plasma samples were obtained and the iodine concentration was measured by X-ray fluorescence analysis. Immediately after the last blood sample, CT was again performed following injection of 120 ml iopromide per 75 kg b.w. A further 3 plasma samples were then obtained 3, 4, and 5 h after CT and used for the determination of high-dose clearance. RESULTS: Low-dose clearance ranged from 20 ml/min to 141 ml/min (mean 78.3 ml/min). High-dose and low-dose clearance correlated excellently, with clearance (high-dose) = 1.4 + 0.994 clearance (low-dose); the correlation coefficient was r = 0.944, the standard deviation SDxy= 9.3 ml/min. CONCLUSION: Plasma clearance of iopromide is dose-independent on use of iodine amounts of 3.6 g and 36 g I/75 kg b.w. The GFR can be determined by high-dose and low-dose iopromide plasma clearance with identical accuracy.

Adult↗
PubMed2002

[Sonography in callus distraction of the hypoplastic mandible].

OBJECTIVES: Since the early 1990's when callus distraction of hypoplastic mandibles was developed, surgeons have been looking for a reliable method to monitor distraction treatment. X-rays films resulted in insufficient quality of images of low calcified structures and are only of little support in follow-up. Therefore, a standardised protocol using ultrasound was introduced. METHODS: 24 patients were included (aged 4 - 29 years with hemifacial microsomy [19], mandibulary micrognathia [5]), 20 intraoral (Howmedica-Leibinger/Mühlheim) and 9 extraoral distractors (Normed/Tuttlingen). Standard procedures for intra- and extraoral distraction were carried out and all postsurgical treatment steps were monitored by ultrasound. RESULTS: The mineralisation of the neocallus shows the following sequence: echogenic dots, needles directed along the distraction direction, bands, plaques, and modulation of the neocompacta. Additional therapeutically relevant questions of distraction distance, inflammation or occurrence of pus, arising during treatment were answered by sonography. Distance measurements could be performed reliably. CAT scan and MRI cannot be carried out because of metal artefacts. X-ray pictures like orthopantomogram and Clementschisch projection cannot show the early mineralisation and do not allow an exact distance measurement. CONCLUSIONS: Sonography is a effective, method to investigate the callus field without using X-rays and supports monitoring and decision making in distraction treatment of hypoplastic mandibles.

Adolescent↗
PubMed2001

Measurement of single kidney contrast media clearance by multiphasic spiral computed tomography: preliminary results.

OBJECTIVE: We present preliminary results of a new method (hereinafter called 'CT-clearance') to measure single kidney contrast media clearance by performing multiphasic helical CT of the kidneys. CT-clearance was calculated according to an extension of the Patlak-Plot. In contrast to prior investigators, who repeatedly measured a single slice, this method makes it possible to calculate single kidney clearance from at least three spiral CTs, utilizing the whole kidney volume. METHODS: Spiral CT of the kidneys was performed unenhanced and about 30 and 100 s after administration of about 120 ml iopromide. Sum-density of the whole kidneys and aortic density was calculated from this data. Using this data, renal clearance of contrast media was calculated by CT-clearance in 29 patients. As reference, Serum-clearance was calculated in 24 patients by application of a modified one-exponential slope model. Information on the relative kidney function was gained by renal scintigraphy with Tc99m-MAG-3 or Tc99m-DMSA in 29 patients. RESULTS: Linear regression analysis revealed a correlation coefficient of CT-clearance with Serum-clearance of r=0.78 with Cl (CT) [ml/min]=22.2+1.03 * Cl (serum), n=24. Linear regression of the relative kidney function (rkf) of the right kidney calculated by CT-clearance compared to scintigraphy results provided a correlation coefficient r=0.89 with rkf(CT)[%]=18.6+0.58 * rkf(scintigraphy), n=29. CONCLUSION: The obtained results of contrast media clearance measured by CT-clearance are in the physiological range of the parameter. Future studies should be performed to improve the methodology with the aim of higher accuracy. More specifically, better determination of the aortic density curve might improve the accuracy.

Contrast Media↗
PubMed2000

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

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.

Adult↗
PubMed2000

[Left ventricular heart volume determination with fast MRI in breath holding technique: how different are quantitative heart catheter, quantitative MRI and visual echocardiography?].

GOAL: Comparison of fast MRI, echocardiography (Echo), and ventricular angiography (Cath) in the assessment of left ventricular global function. METHODS: Fast MRI in short axis plane, biplane Cath, and 2D Echo were performed in 62 patients [35 coronary artery diseases, 16 acquired valvular diseases (VD), 9 dilated cardiomyopathies (DCM), 1 congenital heart disease and 1 heart transplantation]. Enddiastolic (EDV), endsystolic (ESV), stroke volumes (SV), cardiac output (CO), and ejection fraction (EF) were compared in MRI and Cath. EF was visually estimated in 2D Echo by an experienced observer. RESULTS: In comparison to MRI, Cath overestimated EF by 8.4%, and Echo underestimated EF by 5.6%. The limits of agreement between MRI and Cath in EF were +/- 23.8%, between MRI and Echo +/- 18%, and between Echo and Cath +/- 19.4%. Significant differences were found between Cath and MRI in EDV, SV, and CO, but not for ESV. The best agreement in EF was found in the group with DCM, the worst in the group with VD. CONCLUSION: Important systemic and random errors were found in the comparison of MRI, Echo, and Cath. For therapy decision and follow-up, the methods should not be exchanged unscrupulously.

Adult↗
PubMed1999

Right ventricular volumes and ejection fraction with fast cine MR imaging in breath-hold technique: applicability, normal values from 52 volunteers, and evaluation of 325 adult cardiac patients.

Our goal was to establish right ventricular (RV) volume and ejection fraction (EF) values in normal volunteers with fast magnetic resonance (MR) imaging using a breath-hold technique, to assess the frequency and severity of RVEF abnormality in cardiac patients and to compare RV with left ventricular (LV) data. We performed simultaneously derived RV and LV fast cine measurements in 52 normals and 325 patients with coronary artery disease (CAD), acquired valvular disease (VD), cardiomyopathy (CM), or congenital heart disease (CHD). RVEF was reduced in 31% (102) of all patients, in 50% dilated CM, 39% CHD, 34% CAD, and 22% acquired VD patients. Solitary abnormally low RVEF was found in only 15/325 (5%) of all patients, whereas combined with LVEF deterioration in 87/172 (51%) patients. RVEF reduction was mild in 64%, moderate in 25%, and severe in 11%. Although RVEF correlated significantly (r = 0.55, P < 0.001) with LVEF, the predictive value of LVEF for RVEF was low. We conclude that RV volumes can be routinely assessed with fast MRI and should be performed in addition to LV evaluation in CHD, in right-sided VD, and in all patients with an abnormal LVEF.J. Magn. Reson. Imaging 1999; 10:908-918.

Adolescent↗
PubMed1999

[Wish and reality in installation of a clinic-wide system for image and documentation access].

PROBLEM: This report describes the problems that can occur in the representation of the radiological workplace in a digital environment. On one hand the radiologist can sometimes access good equipment in "stand-alone" surroundings (CT, laser printer, workstations,...); on the other hand, the existing insufficient communication between different components is only rarely qualified to support the radiological workflow. This unsatisfactory framework handicaps the required clinic-wide distribution of radiological information. METHODS: From the beginning we defined user groups requiring different radiological data closely associated with specific hard- and software: The radiological workstation in the department for reporting and image processing. The demonstration workstation in wards/outpatient departments for clinicians involved in treatment. Standard PCs with access to the digital medical document for clinicians involved in treatment. At all workstations the medical as well as the legal unity of digital radiological images and the corresponding report is ensured. RESULTS: Only the first two user groups have unrestricted access to the RIS database and to the PACS archive. We have decided that the RIS should be the master of the RIS/PACS-System. For an effective master/slave relationship between RIS and PACS archive and PACS workstations we suggest to mark images and/or series of images. CONCLUSION: The third user group depends on the information exported by the radiologist from PACS. After the report is written and signed by the radiologist, the digital report is transferred from the RIS to the HIS. The report is automatically attached to these images. Authorized personnel at the wards and outpatient are able to read the combination of validated report and exported radiological images as part of the digital medical record with an intranet browser on standard PCs.

Computer Systems↗
PubMed1999

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

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.

Adolescent↗
PubMed1999

[The value of magnetic resonance imaging in the clinical course of osteochondrosis dissecans in the knee and ankle joints].

PURPOSE: Definition of the prognostic value of clinical and morphological findings in the mid-term follow-up of OCD of the femoral condyle and talus. Demonstration of the consolidation of OCD on MRI depending on different therapies. MATERIALS AND METHODS: 76 patients were examined before and at an average of 30 months after conservative or surgical therapy using T1 and T2 weighted SE and 3D-FISP sequences and contrast enhanced studies. Six clinical (age, gender, site, duration and severity of symptoms, therapy) and six morphological (size, signal intensity, fragmentation, contrast enhancement, condition of cartilage, staging) data were registered on first MRI and correlated with the degree of consolidation of OCD (partial and complete remission, no change and progression) on control MRI. RESULTS: Patients under 17 years showed partial or complete remissions in 73%, those of 17 years or older in 33%. Conservatively treated patients had a higher remission rate (54%) than those treated with different surgical techniques (drilling 50%, refixation 43%, abrasio 38%). Small OCDs had a higher remission rate than large lesions (63% vs. 33%). OCDs covered with intact cartilage healed better than lesions with chondral defects (61% vs. 26%). Contrast enhancing fragments had a better prognosis than non-enhancing lesions (100% vs. 40%). CONCLUSIONS: Prognosis of OCD can be better estimated when size of OCD, condition of cartilage and enhancement of contrast agent is graduated with MRI and patient age is registered. The consequences for therapy planning are great.

Ankle Joint↗
PubMed1999

[Accuracy of right and left ventricular heart volume and left ventricular muscle mass determination with cine MRI in breath holding technique].

PURPOSE: To assess the accuracy of right- (RV) and left-ventricular (LV) heart volume and muscle mass determinations by cine MR imaging. MATERIALS AND METHODS: Ten subjects were examined twice by a segmented, ECG-triggered cine sequence in the short axis plane and breath-hold technique by two independent operators and again 4 weeks later by one of the operators. The contours were evaluated manually by two independent examiners and again four weeks later by one of the examiners. LV and RV end-diastolic and end-systolic volumes, stroke volume, cardiac output, ejection fraction (EF), and left-ventricular muscle mass were compared. RESULTS: The RV evaluation variations (RV-EF: 6.46%) were higher than the LV (LV-EF: 4.46%). The intra-examiner variations were smaller than the inter-examiner variations. The generally operators did not cause a significantly increased variation (LV-EF: 5.77%). In contrast, the repeat examinations at different times did lead to a significant increase in the variation (LV-EF: 10.15%). CONCLUSIONS: The rapid ECG-triggered cine MRI in breath-hold technique allows the simultaneous RV and LV, artefact-free determination of heart volumes and LV muscle mass. The LV volumes can be determined more accurately than the RV. The examiner has a distinct influence on the accuracy, the operator has a lesser effect. Physiological fluctuations of cardiac activity significantly influence the follow-up.

Adult↗
PubMed1999

[The determination of left and right ventricular ejection and filling functions of the heart by fast cine MRT in the breath-hold technic in subjects].

PURPOSE: Evaluation and comparison of localized and global left and right ventricular ejection and filling with fast cine MR imaging in the breath-hold technique. MATERIALS AND METHODS: 10 healthy volunteers were examined with a 1.5 Tesla unit and phased-array-coil using a segmented FLASH-2D sequence in breath-hold technique. Peak ejection and peak filling rates [PER, PFR end-diastolic volume (EDV)/s)]. time to PER and PFR [TPER, TPFR ms] and time of end-systole [TSYS in % RR-interval] of all slices (complete-slice-evaluation) were evaluated and compared to three left ventricular and one right ventricular slices (reduced three-slice-evaluation). RESULTS: There were significant regional left ventricular differences of PER (p = 0.002) and PFR (p = 0.007), but not of TPER and TPFR. Ejection and filling indices of the left ventricular middle slice were closest to the overall evaluation of all sections. In the left-/right-side comparison the right ventricular PFR was higher than the left ventricular (5.1 and 4.2 EDV/s) and the right ventricular TPFR was earlier than the left (92.2 and 123.5 ms). CONCLUSIONS: With fast cine techniques, regional and global left and right ventricular ejection and filling indices can be evaluated in addition to the global heart volume indices. The three-slice-evaluation represents a comprehensive, clear and time-saving method for daily routine.

Adult↗
PubMed1999

[Comparison of left and right ventricular ejection and filling parameters of the heart using cine-MRI with breath holding technique. Clinical study of 42 patients with cardiomyopathy and coronary heart disease].

PURPOSE: Quantification of left and right ventricular filling and ejection of localized and diffuse heart diseases with fast cine MR imaging in breath-hold technique. METHODS: 42 patients (14 idiopathic dilated cardiomyopathies (DCM), 13 hypertrophic cardiomyopathies (HCM) and 15 coronary artery diseases (CAD)) and 10 healthy volunteers were examined. Time-volume-curves of three left ventricular and one right ventricular slices were evaluated and peak ejection and filling rates (PER, PFR end-diastolic volume (EDV)/s) time to PER and PFR (TPER, TPFR ms) and time of end-systole (TSYS in % RR-intervall) were calculated. RESULTS: There were significant regional and left-/right-sided differences of the filling and ejection of both ventricles within and between the different groups. In DCM the left ventricular PFR was reduced (DCM 3.1 EDV/s; volunteers 4.9 EDV/s) and Z-SYS prolonged (DCM 50.1%; volunteers 35.4%). In CAD there were localized decreased filling rates in comparison to the normal volunteer group (left ventricle: basal: 2.9 and 6.3 EDV/s, apical: 4.4 and 6.3 EDV/s; right ventricle: 3.6 and 5.7 EDV/s). HCM typically showed an isovolumetric lengthening of the endsystole. CONCLUSIONS: Cardiac MR imaging in breath-hold technique is suitable for measuring contraction and relaxation disturbances of localized and diffuse heart diseases by means of ejection and filling volume indices.

Adolescent↗