Thomas Frohlich

Spatiotemporal filtering of digital angiographic image sequences corrupted by quantum mottle

A method is described for the spatio-temporal filtering of digital angiographic image sequences corrupted by simulated quantum mottle. An x-ray dosage reduction in coronary imaging studies inevitably leads to the introduction of quantum mottle --a Poisson distributed, signal dependent noise that occurs as a result of statistical fluctuations in the arrival of photons at the image intensifier tube. Although spatial filtering of individual frames in the sequence is often performed to improve image quality, this technique does not utilize valuable information from temporal correlations between images. The spatio-temporal filter here estimates motion trajectories for individual pixels and then filters along the direction of motion. This method is different from temporal filtering techniques that do not use motion compensation as the latter always blur the edges of the coronary arteries. Although the method is derived for the estimation of a single frame from two degraded frames of a sequence, it is easily generalized to multi-frame estimates. The performance of the above filter is examined using real image sequences corrupted by quantum mottle.

Coronary artery stenting postcardiac transplant: A report of two cases

Coronary atherosclerosis remains a significant cause of morbidity and mortality following cardiac transplantation. Coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, and directional coronary atherectomy have all been presented as attempted treatment options in this population with generally suboptimal results. Endovascular stenting is a new transcatheter treatment modality with unique potential advantages as compared to other transcatheter revascularization techniques. This report presents the use of endovascular stenting and 6-mo follow-up in two orthotopic cardiac transplant recipients with proximal stenotic posttransplant graft atherosclerosis.

CLINICAL VALIDATION OF ASE 2016 GUIDELINES FOR EVALUATING LEFT VENTRICULAR DIASTOLIC DYSFUNCTION

Background: The new 2016 American Society of Echocardiography (ASE) guidelines aim to improve echocardiographic evaluation of diastolic dysfunction (DD) and left ventricular filling pressure (LVFP). The goal of this study was to compare DD severity grading and estimated LVFP using algorithms from