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Biomedical subjects

Simon Wildermuth

Publications and source records attributed to Simon Wildermuth.

At least 37 records · Page 2Linked to original sources
PubMed2005

Cardiac arrest in a soccer player: a unique case of anomalous coronary origin detected by 16-row multislice computed tomography coronary angiography.

Anomalous origin of the coronary arteries may be present in otherwise normal subjects without clinical significance, but can also be the cause of myocardial ischemia and sudden death in both adults and teenagers. In particular, the origin of the left main coronary artery or left anterior descending artery from the right sinus of Valsalva or right coronary artery may result in compression of the vessel during or immediately after exercise. We present a unique case of coronary anomaly with four separate coronary ostia originating from the right coronary sinus in a soccer player with sudden cardiac arrest. Multislice contrast-enhanced computed tomography has emerged as a valid noninvasive method for the diagnosis of coronary artery anomaly.

Coronary Angiography↗
PubMed2005

Coarctation and aorto-aortic bypass: three-dimensional post-processing using multidetector row computed tomography.

We present the case of a 61-year-old man with a history of dyspnea and disparity in blood pressure of the arms and legs due to a stenotic biscupid aortic valve and a hemodynamically relevant restenosis of a resected coarctation. The coarctation was treated with an extra-anatomic transdiaphragmal aorto-aortic bypass graft. At the same time, the biscupid aortic valve was replaced. Postoperative follow-up contrast-enhanced multidetector row computed tomography (MDCT) and three-dimensional (3D) postprocessing of the axial data sets using the volume-rendering technique was performed. This case of complex vascular structures demonstrates the potency of MDCT combined with the 3D visualization technique.

Aortic Coarctation↗
PubMed2005

Multidetector-row CT angiography of upper- and lower-extremity peripheral arteries.

With the introduction of multidetector-row CT (MDCT) technology indications for MDCT angiography have expanded to include assessment of the peripheral arteries of the upper and lower extremities. Combined with patient- and scanner-adjusted CT data acquisition and contrast medium application strategies, an accurate and reliable evaluation of the peripheral arteries of the upper and lower extremities is possible. MDCT angiography is cost-effective and accurate for detection of arterial stenosis and occlusion in patients with peripheral arterial disease (PAD). MDCT angiography allows postoperative assessment of peripheral arterial bypass grafts, including bypass graft stenosis and occlusion, as well as presence of aneurysms or arteriovenous fistulas. In addition, MDCT angiography is helpful in particular for visualization of arterial bypass grafts with a complicated extra-anatomical course. Furthermore, pre-operative peripheral vascular mapping can be performed by using MDCT angiography. Finally, due to the integration of MDCT scanners in many trauma centres, MDCT angiography is increasingly being used for assessment of traumatic arterial injuries. This article gives an overview of technical aspects of peripheral MDCT angiography, including scanning parameters, contrast medium application, image postprocessing and radiation exposure, and summarizes the most frequent acute and non-acute indications of MDCT angiography for assessment of the upper- and lower-extremity peripheral arteries.

Angiography↗
PubMed2005

3-D CT for cardiovascular treatment planning.

The recently developed 64-slice CT scanner together with the use of 2-D and 3-D reconstructions can aid the cardiovascular surgeon and interventional radiologist in visualizing exact geometric relationships to plan and execute complex procedures via minimally invasive or standard approaches. Cardiac 64-slice CT considerably benefits from the high temporal and spatial resolution allowing the reliable depiction of small coronary segments. Similarly, abdominal vascular 64-slice CT became possible within short examination times and allowing an optimal arterial contrast bolus exploitation. We demonstrate four representative cardiac and abdominal examples using the new 64-slice CT technology which reveal the impact of the new scanner generation for cardiovascular treatment planning.

Cardiovascular Diseases↗
PubMed2005

Image quality of volume rendering of the bronchial tree: Kymogram-gated versus retrospectively ECG-gated and non-gated multi-row detector CT.

RATIONALE AND OBJECTIVE: To compare the image quality of three different heart-cycle-synchronized computed tomography (CT) reconstruction algorithms for volume-rendered (VR) 3D visualization of the bronchial tree. MATERIALS AND METHODS: Kymogram-gated, retrospectively ECG-gated, and non-ECG-gated reconstructions of the bronchial tree were performed from 4-detector-row CT data in 10 subjects. The raw data were reconstructed in 10 phases of the cardiac cycle using ECG-gated and kymogram-gated technique, respectively. For both reconstructions, the optimal artifact-free diastolic phase was determined. VR reconstructions of the bronchial tree were generated from these two data sets and from the non-gated data. Stairstep artifacts of the main bronchi, artifacts in the lung parenchyma, and the extent of bronchial tree visualization were rated by two blinded, independent readers. RESULTS: Kymogram-gated reconstruction showed stairstep artifacts in the main bronchi to the same extent as non-gated reconstruction, but less compared to ECG-gated reconstruction (P < .001). Artifacts in the lung parenchyma were similar with kymogram-gated and non-gated reconstruction, but less compared to ECG-gated reconstruction (P < 0.01). Kymogram-gated reconstruction showed no differences in visualization of segmental and subsegmental bronchi compared to ECG-gated reconstruction, but was inferior to the non-gated reconstruction (P < 0.05). CONCLUSION: Kymogram-gated reconstruction of CT data results in fewer artifacts when compared to the ECG-gated algorithm. Best visualization of the bronchial tree at a low artifact level is obtained with non-gated CT data. It remains therefore the method of choice for VR 3D data post-processing of the bronchial tree.

Adult↗
PubMed2005

Midterm outcome of endovascular repair of ruptured abdominal aortic aneurysms.

PURPOSE: We sought to analyze the clinical and morphologic outcomes of bifurcated stent grafts in patients with ruptured aortoiliac aneurysms at midterm follow-up. METHODS: Thirty-seven patients (4 women; mean age, 73 years; mean abdominal aortic aneurysm [AAA] diameter, 77 mm) underwent endovascular abdominal aneurysm repair between June 1997 and July 2003 for ruptured AAA. Devices inserted were as follows: Vanguard (Boston Scientific, Natick, Mass; n = 7), Excluder (W.L. Gore, Flagstaff, Ariz; n = 25), Talent (Medtronic Vascular, Santa Rosa, Calif; n = 2), and Zenith (Cook Inc, Bloomington, Ind; n = 3). Except for the adjunct postimplantation computed tomographic scanning, the imaging follow-up was the same as for nonruptured AAAs. RESULTS: The mean follow-up period was 24 months (range, 1-59) months. Thirty-day mortality was 10.8%. Three patients died during the follow-up of non-AAA-related causes. One patient was converted early for presumed renal overstenting. The late conversion rate was 9% because of stent graft migration (n = 2) or infection (n = 1). Freedom from endoleak was 57% +/- 8.5% and 48.8% +/- 9% at 2 and 4 years, respectively. Seventeen secondary interventions were performed during the follow-up period, 41% of these within 1 month of stent graft placement. Endoleaks, primary or secondary, were responsible for 58.8% of these interventions. The cumulative risk of a secondary intervention was 35.3% +/- 9% at 2 years and 44.6% +/- 11% at 3 years. Aneurysmal sac shrinkage was observed in 30.8% +/- 9.1% and sac enlargement was observed in 15.3% +/- 10.8% at 2 years. CONCLUSION: Endoluminal devices are able to convert the acute life-threatening situation of ruptured AAA to a controlled situation that results in good patient survival at midterm follow-up.

Aged↗
PubMed2005

Dynamic cine mode imaging of the normal aortic valve using 16-channel multidetector row computed tomography.

BACKGROUND: We investigated the feasibility and image quality of dynamic cine-mode imaging of the normal aortic valve using multidetector row computed tomography (MDCT). MATERIALS AND METHODS: We acquired contrast-enhanced retrospectively echocardiography (ECG)-gated cardiac MDCT datasets of 35 patients (mean age, 62 years; range, 53-77) who received a transoesophageal echocardiography (TOE) precedent to cardiac bypass graft surgery. Twenty data sets in 5% steps of the R-R interval were reconstructed, and data analysis was performed using a 4D software. Read-out of the MDCT data was performed in parallel and perpendicular planes, similar to TOE standard planes, by 2 independent, blinded readers using a 4-point Likert scale (best score: 4) for the following parameters: image quality of the aortic valve components, contrast media enhancement, contrast media inflow related artifacts, and ECG gating-related artifacts. The aortic valve area (AVA) was measured planimetrically and was compared between TOE and MDCT. RESULTS: The best phase for assessing the open valve using MDCT was at 5% and the closed valve at 65% of the cardiac cycle. The mean image quality scores for cine-mode MDCT ranged between 3.26 and 3.75, with inter-reader agreements ranging between good (kappa = 0.723) and excellent (kappa = 1.00). They did not differ significantly from TOE scores for assessment of the closed and open valve. In transitional phases (close-to-open and open-to-close) TOE performed significantly better when compared with static MDCT images, whereas no significant difference was present between cine-mode presentation of MDCT and TOE. Planimetric AVA measurements correlated significantly between TOE and MDCT (Pearson correlation coefficient, r = 0.96; P < 0.0001). Contrast media inflow-related and ECG gating related artifacts were rated as slightly compromising (scores 3.24 and 3.21). CONCLUSION: Retrospectively ECG-gated MDCT offers a noninvasive, accurate, and dynamic imaging method for quantitative and qualitative evaluation of the normal aortic valve allowing determination of morphology and function throughout the cardiac cycle. Further studies regarding assessment of diseased valves are necessary.

Aged↗
PubMed2005

Endovascular repair of inflammatory abdominal aneurysm: a retrospective analysis of CT follow-up.

Retrospective radiologic and clinical midterm follow-up is reported for 10 patients with inflammatory abdominal aortic aneurysm (IAAA) after endovascular aortic aneurysm repair (EVAR). At a mean follow-up of 33 months, regression of the thickness of the perianeurysmal fibrosis (PAF) and decrease of aneurysmal sac diameter was observed in nine patients. Four EVAR-associated complications were observed: periinterventional dissection of femoral artery (n = 1), blue toe syndrome (n = 1), and stent-graft disconnection (n = 2). EVAR is the less invasive method of aneurysm exclusion in patients with IAAA with a comparable evolution of the PAF as reported after open repair.

Aged↗
PubMed2005

Pulmonary Mycobacterium sherrisii infection in a human immunodeficiency virus type 1-infected patient.

We report the first case of a pulmonary infection with Mycobacterium sherrisii in a patient with advanced human immunodeficiency virus infection. Mycobacterium sherrisii is a newly described nontuberculous mycobacterium related to Mycobacterium simiae. Sequencing of the 16S rRNA gene was used for species identification. Treatment and antibiotic susceptibilities are described.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Sixteen-detector row CT angiography for lower-leg arterial occlusive disease: analysis of section width.

Institutional review board approval and written informed consent from all patients were obtained. Diagnostic accuracy of three reconstructions of 16-detector row computed tomographic (CT) angiography data with different section widths and increments (2.0 and 1.0 mm [CT data set 1], 1.0 and 0.5 mm [CT data set 2], and 0.75 and 0.4 mm [CT data set 3]) was compared with that of digital subtraction angiography (DSA) in 163 arterial segments in 17 patients with occlusive peripheral arterial disease (PAD). Arterial visibility was superior with CT as compared with DSA (P < .008). Sensitivity for stenosis detection did not differ between the CT reconstructions, whereas specificity was significantly improved when CT data set 3 was used (P < .017). Stenosis length did not differ significantly between CT angiography and DSA. Accuracy of stenosis detection was 88.2%, 90.8%, and 96.1% with CT data sets 1, 2, and 3, respectively. CT angiography has excellent diagnostic accuracy in the assessment of lower-leg PAD provided that the thinnest possible section width is used.

Aged↗
PubMed2005

Interosseous ligament tears of the wrist: comparison of multi-detector row CT arthrography and MR imaging.

PURPOSE: To compare the accuracy of multi-detector row computed tomographic (CT) arthrography and magnetic resonance (MR) imaging in depicting tears of dorsal, central, and palmar segments of scapholunate (SL) and lunotriquetral (LT) ligaments in cadavers. MATERIALS AND METHODS: Cadaver wrists were obtained and used according to institutional guidelines and with informed consent of donors prior to death. Nine cadaver wrists of eight subjects were evaluated. MR images were obtained with a 1.5-T MR unit. Imaging protocol included intermediate-weighted coronal and transverse fast spin-echo and coronal three-dimensional gradient-echo sequences. Multi-detector row CT arthrography was performed after tricompartmental injection of 3-6 mL of contrast material with a concentration of 160 mg per milliliter of iodine. Palmar, dorsal, and central segments of both ligaments were analyzed on transverse and coronal MR images and multiplanar multi-detector row CT reconstructions by two musculoskeletal radiologists working independently. Open inspection of the wrists was the reference standard. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated from the imaging and gross pathologic readings. Statistical significance was calculated with the McNemar test. Weighted kappa values for interobserver agreement were calculated for both imaging modalities. RESULTS: All ligament segments could be visualized in all cases with both imaging modalities. CT arthrography was more sensitive (100%) than MR imaging (60%) in detection of palmar segment tears (P = .62); specificity of both imaging modalities was 77%. Sensitivity (CT arthrography, 86%; MR imaging, 79%) and specificity (CT arthrography, 50%; MR imaging, 25%) for detection of the central segment tears were determined. Dorsal segment tears were detected only with CT arthrography, while all tears were missed with MR imaging (P = .02). Interobserver agreement was better for multi-detector row CT arthrography (kappa = 0.37-0.78) than for MR imaging (kappa = -0.33 to -0.10). CONCLUSION: Performance in depiction of palmar and central segment tears of SL and LT ligaments is almost equal for multi-detector row CT arthrography and MR imaging, with much higher interobserver reliability for CT arthrography. CT arthrography is significantly superior to MR imaging in the detection of dorsal segment tears of SL and LT ligaments.

Aged↗
PubMed2005

Dynamic cine imaging of the mitral valve with 16-MDCT: a feasibility study.

OBJECTIVE: Our aim was to assess the feasibility and image quality of dynamic cine-mode imaging of the mitral valve using retrospectively ECG-gated 16-MDCT. SUBJECTS AND METHODS: Contrast-enhanced MDCT was performed in 37 patients who have a normal mitral valve, as shown on transesophageal echocardiography. Twenty CT data sets covering the valve apparatus were reconstructed every 5% step of the R-R interval. Multiplanar reconstructions were performed in the parallel short axis and perpendicular long axis of the left ventricle. Two independent blinded reviewers evaluated the image quality for dynamic cine-mode visualization of the valve components in systole and diastole and during the transitional phases in between. RESULTS: Interobserver agreement for image quality ratings of valve components in all cardiac cycle phases ranged from good to excellent. Image quality for the visualization of valve leaflets, apposition zone, commissures, and mitral annulus (ranging from adequate to excellent) was significantly superior on perpendicular plane images than on parallel plane images for all cardiac phases (p < 0.05). Tendinous cords were visualized on both perpendicular and parallel planes with bad to adequate quality, whereas visualization of the papillary muscles was adequate to excellent on both imaging planes. Visualization of each valve component was superior in systole and diastole in both imaging planes as compared with the transitional phases (p <0.001). CONCLUSION: Noninvasive cine-mode imaging of the mitral valve using retrospectively ECG-gated MDCT is feasible and allows accurate visualization of the moving valve. Perpendicular long-axis reconstructions yield images of superior quality when compared with the short-axis reconstructions and enable a determination of its functional morphology.

Aged↗
PubMed2004

Evaluation of radiological workstations and web-browser-based image distribution clients for a PACS project in hands-on workshops.

The methodology and outcome of a hands-on workshop for the evaluation of PACS (picture archiving and communication system) software for a multihospital PACS project are described. The following radiological workstations and web-browser-based image distribution software clients were evaluated as part of a multistep evaluation of PACS vendors in March 2001: Impax DS 3000 V 4.1/Impax Web1000 (Agfa-Gevaert, Mortsel, Belgium); PathSpeed V 8.0/PathSpeed Web (GE Medical Systems, Milwaukee, Wis., USA); ID Report/ID Web (Image Devices, Idstein, Germany); EasyVision DX/EasyWeb (Philips Medical Systems, Eindhoven, Netherlands); and MagicView 1000 VB33a/MagicWeb (Siemens Medical Systems, Erlangen, Germany). A set of anonymized DICOM test data was provided to enable direct image comparison. Radiologists ( n=44) evaluated the radiological workstations and nonradiologists ( n=53) evaluated the image distribution software clients using different questionnaires. One vendor was not able to import the provided DICOM data set. Another vendor had problems in displaying imported cross-sectional studies in the correct stack order. Three vendors (Agfa-Gevaert, GE, Philips) presented server-client solutions with web access. Two (Siemens, Image Devices) presented stand-alone solutions. The highest scores in the class of radiological workstations were achieved by ID Report from Image Devices ( p<0.005). In the class of image distribution clients, the differences were statistically not significant. Questionnaire-based evaluation was shown to be useful for guaranteeing systematic assessment. The workshop was a great success in raising interest in the PACS project in a large group of future clinical users. The methodology used in the present study may be useful for other hospitals evaluating PACS.

Computer Communication Networks↗
PubMed2004

Computational simulation of intracoronary flow based on real coronary geometry.

OBJECTIVE: To assess the feasibility of computationally simulating intracoronary blood flow based on real coronary artery geometry and to graphically depict various mechanical characteristics of this flow. METHODS: Explanted fresh pig hearts were fixed using a continuous perfusion of 4% formaldehyde at physiological pressures. Omnipaque dye added to lead rubber solution was titrated to an optimum proportion of 1:25, to cast the coronary arterial tree. The heart was stabilized in a phantom model so as to suspend the base and the apex without causing external deformation. High resolution computerized tomography scans of this model were utilized to reconstruct the three-dimensional coronary artery geometry, which in turn was used to generate several volumetric tetrahedral meshes of sufficient density needed for numerical accuracy. The transient equations of momentum and mass conservation were numerically solved by employing methods of computational fluid dynamics under realistic pulsatile inflow boundary conditions. RESULTS: The simulations have yielded graphic distributions of intracoronary flow stream lines, static pressure drop, wall shear stress, bifurcation mass flow ratios and velocity profiles. The variability of these quantities within the cardiac cycle has been investigated at a temporal resolution of 1/100th of a second and a spatial resolution of about 10 microm. The areas of amplified variations in wall shear stress, mostly evident in the neighborhoods of arterial branching, seem to correlate well with clinically observed increased atherogenesis. The intracoronary flow lines showed stasis and extreme vorticity during the phase of minimum coronary flow in contrast to streamlined undisturbed flow during the phase of maximum flow. CONCLUSIONS: Computational tools of this kind along with a state-of-the-art multislice computerized tomography or magnetic resonance-based non-invasive coronary imaging, could enable realistic, repetitive, non-invasive and multidimensional quantifications of the effects of stenosis on distal hemodynamics, and thus help in precise surgical/interventional planning. It could also add insights into coronary and bypass graft atherogenesis.

Animals↗
PubMed2004

Resolution of hoarseness after endovascular repair of thoracic aortic aneurysm: a case of Ortner's syndrome.

We report the case of a 75-year-old man with a 6-month history of hoarseness due to a left recurrent laryngeal nerve palsy. Investigations revealed a thoracic aortic aneurysm compressing the left recurrent nerve; thus, the diagnosis of Ortner's syndrome, ie, cardiovocal syndrome, could be established. The aortic aneurysm was repaired by implantation of an endovascular stent graft under local anesthesia. The patient was discharged 5 days later, and at the 1-year follow-up visit the hoarseness had resolved completely. This case demonstrates for the first time the reversal of Ortner's syndrome after endoluminal aneurysm repair.

Aged↗
PubMed2004

Effects of ECG gating and postprocessing techniques on 3D MDCT of the bronchial tree.

OBJECTIVE: Our goal was to determine the impact of ECG gating and different postprocessing techniques on 3D imaging of the bronchial tree. SUBJECTS AND METHODS. Retrospective ECG-gated MDCT and non-ECG-gated MDCT of the chest were performed in 25 patients. ECG-gated MDCT data were reconstructed mid diastole using a fixed interval of -400 msec in 25 patients and then additionally at -200, -300, and -500 msec in 10 of those patients. Shaded surface display and volume rendering of the bronchial tree combined with virtual bronchoscopy were performed using all data sets. The extent of bronchial tree visualization in shaded surface display-virtual bronchoscopy and volume rendering-virtual bronchoscopy and the presence of artifacts in volume-rendered images were scored by three blinded reviewers. The effective radiation doses of the ECG-gated and nongated acquisitions were compared. RESULTS: The summary scores of all bronchial segments for gated shaded surface display-virtual bronchoscopy and gated volume rendering-virtual bronchoscopy did not differ significantly. The summary scores for nongated shaded surface display-virtual bronchoscopy and nongated volume rendering-virtual bronchoscopy were not significantly different. Non-gated acquisition yielded significantly better visualization of the bronchial tree for both post-processing techniques, regardless of the time interval used for reconstruction of the ECG-gated series. Artifact scores in volume-rendered images were significantly higher for ECG-gated MDCT compared with nongated MDCT. Effective radiation dose was significantly higher for the ECG-gated acquisition. CONCLUSION: Given the advantage of volume rendering for representing the entire data set and given the lower radiation dose and better 3D image quality of nongated acquisition, volume rendering performed on nongated MDCT data is the method of choice for 3D visualization of the bronchial tree.

Bronchography↗
PubMed2003

Thin-section CT of the lung: does electrocardiographic triggering influence diagnosis?

PURPOSE: To determine the impact of prospective electrocardiographic (ECG) triggering on image quality and diagnostic outcome of thin-section computed tomography (CT) of the lung. MATERIALS AND METHODS: Forty-five consecutive patients referred for thin-section CT of the lung were examined with prospectively ECG-triggered and nontriggered thin-section CT of the lung with a multi-detector row helical CT scanner. Subjective image quality criteria (image noise, motion artifacts, and diagnostic accessibility) were rated by three radiologists in consensus for the upper lobe, middle lobe and/or lingula, and lower lobe. Pathologic changes were assessed for the various lobes, and a diagnosis was assigned. The diagnoses were compared by two radiologists in consensus to determine the effects of CT technique on diagnostic outcome. Quantitative measurements were performed, including determination of image noise and signal-to-noise ratios in different anatomic regions. The Wilcoxon signed rank test and paired sign test (both with Bonferroni correction) were used for statistical analysis. RESULTS: Subjective assessment showed significant differences in motion artifact reduction in the middle lobe, lingula, and left lower lobe. The diagnostic assessibility of triggered CT was rated significantly higher only for the left lower lobe compared with nontriggered data acquisition. No differences in diagnostic outcome were determined between triggered and nontriggered techniques. Mean image noise in tracheal air was 68.2 +/- 17 (SD) for triggered CT versus 37.4 +/- 9 for nontriggered CT (P <.05). Mean signal-to-noise ratio in the upper versus lower lobes was 22.5 +/- 8 versus 25.4 +/- 10 for triggered and 35.6 +/- 9 versus 39.2 +/- 10 for nontriggered techniques (P <.05). CONCLUSION: Given the lack of improvement in diagnostic accuracy and the need for additional resources, ECG-triggered thin-section CT of the lung is not recommended for routine clinical practice.

Adult↗