Carotid artery stenosis: contrast-enhanced MR angiography with two different scan times compared with digital subtraction angiography.

Contrast enhanced magnetic resonance angiography (CE MRA) is a non-invasive alternative to conventional digital subtraction angiography (DSA). CE MRA is increasingly used as a complement to Duplex in the preoperative assessment of carotid artery stenosis. The purpose of this study was to determine if CE MRA could replace preoperative DSA. CE MRA with a scan time of 10 or 28 s was performed in 24 consecutive patients who were scheduled for preoperative DSA because of Duplex-verified severe carotid artery stenosis. Two neuroradiologists measured the degree of stenosis with three different methods, and the image quality was evaluated. DSA was used as the gold standard. For detection of severe stenosis (N. American symptomatic carotid endarterectomy trial (NASCET) > or =70%; European symptomatic carotid endarterectomy trial (ECST) > or =80%; common carotid artery method (CCAM) > or =80%), the sensitivity of CE MRA maximum intensity projection (MIP) compared with DSA was 82%-100 %, the specificity was 74%-93% and the accuracy was 77%-90%. The inter-observer agreement was higher, the image quality was better and the intracranial main arteries were better visualized with the 28 s than with the 10 s scan time. The enhancement of the jugular veins seen in 17% of the 10 s scans and in 58% of the patients with the 28 s scans did not interfere with the evaluation of the carotid arteries. CE MRA, preferably with a scan time of 28 s, can replace DSA in the preoperative assessment of most patients with carotid artery stenosis.

Assessment of image post-processing and of measuring assistance tools in computed radiography. Evaluation of the weight-bearing knee.

PURPOSE: A system for the examination and measurement of the weight-bearing knee was adapted to computed radiography (CR) and to a picture archiving and communication system (PACS). The examination and measurement system was developed on examination equipment used for QUESTOR precision radiography (QPR). For an easier and more standardised localisation of bony landmarks on the screen, 4 measuring assistance tools (MATs) were developed. The aim of this study was to evaluate the usefulness of the tools developed and of image post-processing, specifically as magnification (zoom) and filtering (edge enhancement), by determining intra-observer variation in the measurement of angles and distances. MATERIAL AND METHODS: The original QPR measurement program, generating 19 angles and distances corrected for parallax and magnification, was converted and installed on a multi-modality workstation (Imtec Image 1200). A CR system (Fuji AC-2) was used for the generation of the related images and the measurements were made on the workstation. Four unilateral examinations of weight-bearing knees were undertaken. These examinations were measured twice under 5 different measurement conditions by 4 viewers. RESULTS AND CONCLUSIONS: The most important factor in reducing intra-observer variation was the ability to magnify (zoom) the images. The MATs also reduced variation. Filtering (edge enhancement), however, did not affect precision.

Leg temperature profiles with a simplified thermographic technique in the diagnosis of acute venous thromboses.

A simplified thermographic technique has been developed to provide continuous leg temperature profiles by manual scanning with a noncontactile infrared radiation transducer connected to a linera potentiometer for determination of the transducer position. The clinical value of the technique in the diagnosis of acute venous thromboses has been estimated in seventy patients and thirty controls, using plethysmography and phlebography as methods of reference. The thermographic diagnosis was based on side differences in temperature levels within different segments of the limbs, as calculated from the temperature profiles by means of planimetric technique. Standardized temperature profiles from the medial side of the limbs were found to demonstrate a side difference above the reference level in fifty-seven of fity-nine patients with acute venous thromboses, which means a diagnostic sensitivity corresponding to that of conventional thermography. Skin temperature profiles were superior to plethysmography, particularly in the diagnosis of thromboses located distally. Falsely positive results were obtained, as expected, in some cases of varicose veins or acute arthritis and skin infections. The presented type of thermography has obvious qualifications as a screening method in the early diagnosis of acute venous thromboses, being far less expensive but never the less more suited for objective numerical analyses and evaluation than conventional thermography with scanning cameras.