Knud-Erik Fredfeldt

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This prospective study evaluates the usefulness of the twinkling artefact (TA) seen on colour-Doppler ultrasound (US) in diagnosing urolithiasis. US and standard computed tomography (CT) were performed blinded on 105 patients. B-mode US and colour-Doppler used separately and in combination showed 55% sensitivity and 99% specificity (positive predictive(More)
Simple experiments which form the basis for a true 3-D demonstration of sectional images are presented and a method for genuine 3-D display of dynamic ultrasound images is described. Eight ultrasound images are recorded with a slightly different angulation of the transducer. The images are extracted from the video signal from a conventional ultrasound(More)
To determine tumor stage, 115 bladder cancer patients with cystoscopic suspicion of invasion underwent transurethral ultrasonic scanning. Seventeen patients who had received radiotherapy were excluded because it proved impossible to differentiate between tumor and irradiation sequelae. Of the remaining 98 examinations, 4 (4.1%) were inconclusive, 73 tumors(More)
Determination of the velocity of ultrasound seems a promising way of monitoring diffuse bone mineral disease. Measurements have been made on 13 healthy adults, 3 healthy children, and 17 patients submitted to haemodialysis. The mean ultrasound velocity in the middle phalanges of the hand was found to be 2403 m/s in the normal adults, 2109 m/s in the(More)
PURPOSE The authors, forming part of a multicenter project funded by the European Community, summarize the validation of a tissue-mimicking flow Doppler test object and of procedures for testing medical diagnostic Doppler equipment. The results of the project are expected to contribute to a future international IEC Standard concerning flow Doppler test(More)
A consecutive series of 102 patients admitted to the radiology department for emergency intravenous urography (IVP) due to suspected obstructing urinary calculus, had an ultrasound scanning (US) performed immediately prior to the requested IVP. The scannings were performed by US-specialists who had access to all patient data except the IVP result. IVP(More)
The zerocrossing method for measurement of the frequency dependence of ultrasound attenuation was used to study the livers of 10 healthy subjects and 9 patients. Increased attenuation in vivo was observed in 5 patients who were seen to have a 'bright liver' during B-scanning. Normal attenuation was seen in 3 patients who had pathologic liver biopsies, but(More)
Ten formalin-fixed atherosclerotic carotid plaques removed by endarterectomy were molded into rectangular agar blocks containing fiducial markers on the top surface. Plaque and fiducial markers were imaged with 3-D multiangle ultrasound (US) spatial compounding as well as planar X ray. Subsequently, the blocks were decalcified, sliced, photographed and(More)
Using the computer as a diagnostic tool is a normal everyday function of modern radiology departments with CT, MRI, and ultrasound. This article describes the preliminary results using the computer as a coworker in a diagnostic scrutinizing process. Conventional analogous mammographic films were digitized and analyzed. Promising results were obtained(More)