Biomedical subjects

Walter Heindel

Publications and source records attributed to Walter Heindel.

77 records · Page 5Linked to original sources

PubMed2002

Revealing in-stent stenoses of the iliac arteries: comparison of multidetector CT with MR angiography and digital radiographic angiography in a Phantom model.

OBJECTIVE: Our objective was to evaluate the detectability of in-stent stenoses in iliac artery stents using multidetector CT angiography in comparison with MR angiography and digital radiographic angiography. MATERIALS AND METHODS: Ten different metallic stents (made of steel, nitinol, tantalum, or cobalt) were implanted in plastic tubes (8 mm). The stent lumina were partially obstructed by wax (CT density, -30 H) resulting in 50-60% in-stent stenoses. The tubes were filled with diluted contrast material (25 mmol/L of gadopentetate dimeglumine or 6 mg I/mL of iodinated contrast material) and placed in a plastic container filled with oil or water, respectively. CT angiography was performed on a four-detector CT scanner (detector collimation, 4 x 1 mm; slice thickness, 1.25 mm; table feed, 4 mm per rotation). MR angiography was performed on a 1.5-T system with a three-dimensional gradient-echo sequence (TR/TE, 4.6/1.8; flip angle, 30 degrees; slice thickness, 1.88 mm). Axial and longitudinal reformations of CT and MR imaging data were evaluated regarding the in-stent attenuation and signal intensity, the visible lumen diameter inside the stent, and the delineation of the stenoses. For comparison, digital radiographic angiography was performed as the gold standard. RESULTS: The degree and character of stent-related artifacts differed in CT angiography and MR angiography. In CT angiography, only the tantalum stent caused artifacts that obscured the stenosis; in all other cases, the stenoses were visible. In MR angiography, depiction of stenoses was impaired in two steel stents but possible in the tantalum and most nitinol stents. CONCLUSION: CT angiography is suited for detection of relevant stenoses in steel, cobalt-based, and nitinol stents. MR angiography is superior only in tantalum products.

Angiography↗

PubMed2002

Using ECG-gated multidetector CT to evaluate global left ventricular myocardial function in patients with coronary artery disease.

OBJECTIVE: Retrospectively ECG-gated three-dimensional volume data from multidetector CT (MDCT) coronary angiography enable image reconstruction of the cardiac cycle in the diastolic and systolic phases. The objective of our study was to investigate the feasibility of determining left ventricular function from MDCT coronary angiography data sets in 22 patients with coronary artery disease and to study the correlation of MDCT results with those of functional data from biplane cineventriculography. CONCLUSION: Multiplanar reformations from three-dimensional MDCT data allowed good delineation of endocardial and epicardial left ventricular contours. In patients evaluated for coronary artery disease, MDCT coronary angiography with retrospective ECG gating provides functional data in an acceptable correlation (r = 0.8; p < 0.05) to biplane cineventriculography.

Adult↗

PubMed2001

Automatic detection of pulmonary nodules at spiral CT: clinical application of a computer-aided diagnosis system.

The aim of this study was to evaluate a computer-aided diagnosis (CAD) workstation with automatic detection of pulmonary nodules at low-dose spiral CT in a clinical setting for early detection of lung cancer. Eighty-eight consecutive spiral-CT examinations were reported by two radiologists in consensus. All examinations were reviewed using a CAD workstation with a self-developed algorithm for automatic detection of pulmonary nodules. The algorithm is designed to detect nodules with diameters of at least 5 mm. A total of 153 nodules were detected with at least one modality (radiologists in consensus, CAD, 85 nodules with diameter < 5 mm, 68 with diameter > or = 5 mm). The results of automatic nodule detection were compared to nodules detected with any modality as gold standard. Computer-aided diagnosis correctly identified 26 of 59 (38%) nodules with diameters > or = 5 mm detected by visual assessment by the radiologists; of these, CAD detected 44% (24 of 54) nodules without pleural contact. In addition, 12 nodules > or = 5 mm were detected which were not mentioned in the radiologist's report but represented real nodules. Sensitivity for detection of nodules > or = 5 mm was 85% (58 of 68) for radiologists and 38% (26 of 68) for CAD. There were 5.8+/-3.6 false-positive results of CAD per CT study. Computer-aided diagnosis improves detection of pulmonary nodules at spiral CT and is a valuable second opinion in a clinical setting for lung cancer screening despite of its still limited sensitivity.

Adult↗

PubMedDate not supplied

Transbrachial thrombolysis, PTA and stenting in the lower extremities.

We present an analysis of 37 interventions in the arteries of the lower limbs via a transbrachial arterial approach. Twenty-six patients (42-79 years) underwent 37 interventional procedures in the lower extremities (iliac n = 6, iliac + femoro-popliteal n = 1, femoro-popliteal n = 30) with a vascular approach via the brachial artery (33 left sided, 4 right sided, introducer sheath 4-7 F). The transbrachial approach was chosen to avoid puncture of femoral bypass graft material. Technical success could be achieved in 11/13 thrombolyses, 8/9 PTAs, 7/10 combinations of thrombolysis and percutaneous transluminar angioplasty (PTA) and in the placement of two stents. One patient suffered from periprocedural severe re-thrombosis due to insufficient anticoagulation during fibrinolysis, and twice thrombolysis was incomplete. One puncture-related false aneurysm of the brachial artery had to be corrected surgically. One transient ischemic attack (TIA) and four minor complications occurred. Transbrachial vascular approach for arterial interventions in iliac and femoro-popliteal pathologies is a reasonable alternative to the transaxillary access if transfemoral puncture has to be avoided. The technical success rate is comparable with the results of the transaxillary and transfemoral approach. To minimize, at least theoretically, the risk of cerebral complications, the left-sided approach should be preferred and intravenous heparin should be administered routinely.

Adult↗

PubMedDate not supplied

Cine and tagged magnetic resonance imaging in short-term stunned versus necrotic myocardium.

We investigated the potential of Cine and 2D Tagged Cardiac Magnetic Resonance (CMR) Imaging to distinguish stunned from necrotic left ventricular (LV) myocardium in the early postischemic phase in an open-chest animal model (N = 12). Reversible and permanent occlusion of the LAD coronary artery resulted in global LV dysfunction in both groups without significant differences. LAD perfused segments revealed significant higher values for end systolic wall thickening (ESWT) and percentual systolic wall thickening in animals with stunned myocardium. Analysis of strain parameters showed significant regional differences (maximal principal strain lambda1, deviation angle beta) between postischemic and remote myocardium within both groups, however results were not significantly different comparing animals with stunned myocardium to animals with myocardial necrosis. In conclusion, at rest neither global LV functional nor regional strain parameters derived from Cine and 2D Tagged CMR Imaging can distinguish animals with short-term stunned myocardium from respective animals with necrotic myocardium. Diagnostic value of ESWT is limited due to the spatial resolution of the gradient-echo sequence used.

Animals↗