A method to create reference maps for evaluation of ultrasound images of carotid atherosclerotic plaque.

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 analyzed histologically. This gave a total of 123 slices. The plaque regions of the photographs were outlined and the outline adjusted to partly compensate for occasional displacement during slicing. Inside this outline, the material constitutions were found by incorporating the histologic information. From this set, slices with 1. too much tissue displacement due to cutting or 2. lack of identification of calcification as found by x ray, were removed. This resulted in 53 reference maps. The material types identified covered soft tissues, fibrous tissue, calcified tissue and unidentified tissues. The 53 reference maps can be used for direct automated quantitative comparison with US images.

Automatic screening of plain film mammography.

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 detecting microcalcifications, dense areas, and their borderlines and stellate configurations. There are problems with detecting skin changes, probably caused by insufficient digitizing.

Ultrasound versus intravenous urography in the initial evaluation of patients with suspected obstructing urinary calculi.

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 diagnosed renal outlet obstruction in 53 of the 102 cases. This was correctly diagnosed by US in 50 cases. In three cases where IVP described acute obstruction ("white kidney") no dilatation was visible on US. The false negative rate concerning obstruction was thus 6%. No false positive US investigations occurred. Five cases of uretero-pelvic stenosis were correctly diagnosed at both investigations. 18 kidney stones--two being obstructing--were found at both investigations. IVP diagnosed 40 of 46 ureteral stones. The remaining stones were diagnosed by other means (retrograde pyelography, ureteroscopy). US only visualized 18 ureteral stones. The overlooked stones were all less than 5 mm in size, the major part being situated in the middle and lower ureter. We conclude that US plays a role in the initial evaluation of patients with suspected obstructing urinary calculi. If obstruction is diagnosed emergency IVP may be substituted by an elective investigation or even omitted. If no obstruction is diagnosed IVP must be performed in order to rule out non-dilated obstruction. IVP remains the gold standard for visualization of the urinary tract in patients with suspected acute obstruction.

Sound velocity in the middle phalanges of the human hand.

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 children, and 2360 m/s in the haemodialysis group. One person had known halisteresis and had a velocity significantly lower than in the normal group. The method is fast and harmless and might be used in screening procedures or at follow-up examinations in patients at risk. However, a prerequisite for this is further investigation of the normal relationships of velocity to age and to actual bone mineral content.

Relative attenuation measurements of ultrasound in the liver using the zerocrossing method.

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 normal B-scan images. Increased attenuation was seen in one patient who had a nodular appearance of the liver during B-scanning; biopsy showed steatosis. These results indicate that the zerocrossing method makes it possible to quantify some of the changes seen in the B-scan image. A detailed description, including block diagrams, is given of a zerocrossing detector which can be connected to a commercially available scanner (Brüel & Kjaer Ultrasound Scanner Type 1846).

Three-dimensional ultrasonic scanning.

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 scanner and stored in eight digital memories. After recording, each image is displayed on an oscilloscope screen, which is viewed via a fast oscillating mirror. The position of the mirror determines which of the eight images are to be displayed and thereby ensures a correct spatial relationship of the images, resulting in a true 3-D scan presentation.

[A test object for quality control of the instrument for doppler (duplex) ultrasonography, based on the Draft IEC 61685 Standard]. / Ein Testobjekt für die apparative Qualitätssicherung bei Ultraschall-Doppler(Duplex)-Geräten, ausgehend vom Normenentwurf IEC 61685.

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 objects (Draft IEC 61685 Standard) and for the European Medical Device Directive (MD 93/42/EEC). METHODS: Within this project a test protocol was developed that includes a set of different procedures, suitable for checking Spectral and Colour Doppler systems. The performance parameters for describing the image quality as well as the accuracy and the correct functioning of a system are in accordance with the definitions made in the Draft IEC 61685 Standard. RESULTS: A survey of the design and materials used for this Doppler test object will be presented with a special emphasis on the suitability of the procedures for routine measurement of performance parameters in hospitals. CONCLUSION: The test object satisfies the requirements of the Draft IEC 61685 Standard. The test procedures in combination with this test object can be used for checking different transducer models with nominal frequencies between 2.5-10.0 MHz.

Bladder tumor staging by transurethral ultrasonic scanning.

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 (74.5%) were correctly staged, 16 tumors (16.3%) were overstaged and 5 tumors (5.1%) understaged. Transurethral ultrasound is regarded a useful supplement to cytoscopy and biopsy in staging of bladder tumors suspected of invasion.