No abstract

Ultrasound techniques have been used for the non-invasive, quantitative characterisation of muscle tissue in normal subjects and volunteer patients. Radio frequency (RF) echoes from a volume of tissue have been digitised and analysed using computer techniques. Attention has been given to the correct positioning and orientation of the transducer during examination due to the importance of the angle dependence of the interaction of ultrasound with muscle fasciculi. Several different muscles in the leg, arm and back of normal subjects have been examined, whereas patient studies have concentrated on the vastus intermedius. Ultrasonic data from patients with muscular dystrophy have been correlated with measurements of muscle tissue density obtained using X-ray computerised tomography (X-ray CT). The technique shows that ultrasound can be used to differentiate between normal and diseased muscle quantitatively. Results indicate that pathological change can be detected and monitored earlier with ultrasound than with X-ray CT. These quantitative methods are now in use as a guide to the staging and monitoring of pathological change in muscle.

Five postmortem fetuses were scanned by magnetic resonance (MR) imaging. Of eight three-dimensional (3D) data sets reconstructed on an MGI workstation, five sets demonstrated detailed 3D fetal cardiac structures, and one depicted clear information regarding the disposition and compression of the heart and lungs in diaphragmatic hernia. This study has shown the potential of 3D MR imaging in support of postmortem examination and for interactive visual teaching of the fetal cardiac structures. The new technique may eventually be of significance in prenatal detection of cardiac abnormalities with the development of fast real-time MR imaging.

The technique has the potential for recording complete anatomic studies for review and visualization of detail that is difficult to perceive on conventional US scans.

No abstract

Left ventricular performance during percutaneous transluminal coronary angioplasty was assessed in 52 patients by intravenous digital subtraction ventriculography. After injection of contrast into the right atrium ventriculograms were obtained before and during balloon inflation. In 37 patients they were also obtained after the procedure. A 12 lead electrocardiogram was monitored throughout. During balloon inflation the left ventricular ejection fraction fell (from 73% to 57%) in all but one patient; the decreases in patients with single vessel or multivessel disease were similar. The fall in left ventricular ejection fraction during percutaneous transluminal coronary angioplasty ofthe left anterior descending artery (19%) was significantly greater than that during balloon inflation in the right coronary (10%) or circunflex (8%) coronary arteries. It also reduced anterobasal, anterior, and apical segmental shortening while right coronary percutaneous transluminal coronary angioplasty affected inferior and apical segments. In 33 (63%) patients the ST segment was altered during balloon inflation. The fall in left ventricular ejection fraction correlated significantly with the magnitude of both ST segment elevation (r = 0 637) and ST depression (r = 0 396). Left

To evaluate the significance of "reciprocal" ST segment depression resulting from coronary occlusion, 27 patients with single vessel coronary disease were studied with intravenous digital subtraction left ventriculography before and during angioplasty of the left anterior descending coronary artery. During balloon inflation, 13 patients developed inferior lead ST depression in addition to anterior lead ST elevation (Group 1), whereas the remaining 14 patients did not (Group 2). The degree of anterior lead ST elevation in Group 1 (5 mm) was greater than that in Group 2 (1.5 mm, p less than 0.001) as was the reduction in left ventricular ejection fraction (24% versus 13%, respectively; p less than 0.02). Anterior and apical regional shortening decreased in both groups similarly, but an additional decrease in anterobasal shortening was confined to Group 1 (from 38% to 21%; p less than 0.002). Despite the presence of inferior lead ST depression in Group 1, inferior regional shortening did not change and inferobasal contraction was enhanced (from 4% to 29%; p less than 0.01). Inferior lead ST segment depression during anterior descending coronary angioplasty reflects a greater degree of anterior wall ischemia. The concurrent preservation of inferior wall contraction and the augmentation of infero-basal shortening confirm that this electrocardiographic feature is a "reciprocal" phenomenon rather than a manifestation of remote ischemia.

This new tool represents a major advance in imaging techniques and promises to provide new knowledge in understanding the hydrodynamics of the lower urinary tract. The precise geometry of the 3-D urethra will also help in the design of new stents.