Detection of air emboli in radiographic contrast media by microwave radiometry.

To evaluate the efficacy of a microwave radiometry system in detecting in-line air emboli in radiographic contrast media, air emboli ranging in volume from 0.1 to 0.005 ml were introduced into ionic (ioxaglate) and nonionic (iohexol) contrast media at 22 or 37 degrees pumped at flow rates of 16.7, 180 or 300 ml/min through polyvinlychloride tubing with an inner diameter of 0.100 inches (2.54 mm) over which was fitted a radiometer antenna connected to a Microwave Medical System F+ radiometer and a computerized data acquisition system. A total of 400 determinations were run, with 10 replicate determinations for each unique set of experimental conditions. The success of air emboli detection was not significantly related to contrast media (p = 0.73) or contrast temperature (p = 0.68). Embolus volume (p < 0.0001) and pump speed (p < 0.0001) were significant factors affecting system performance. The system could reliably detect small (0.005 ml) emboli in both ionic and nonionic low-osmolar contrast media.

Early detection of extravasation of radiographic contrast medium. Work in progress.

Microwave radiometry is a passive and noninvasive technique that allows quick detection of subcutaneous temperature changes. The feasibility of this technique for differentiating normal intravenous infusions of radiographic contrast medium from extravasations of contrast medium was tested in anesthetized dogs. Room-temperature and heated ionic and nonionic contrast media were administered at flow rates ranging from 0.2 to 9.9 mL/sec by means of a power injector. On the basis of these experiments, an algorithm to adjust for extravasation detection thresholds as a function of injection flow rates was developed. With this algorithm, results showed a false-positive rate of 0% at all infusion rates and false-negative rates of 2%, 2%, and 4% at pump speeds of 0.2, 1.0, and 9.9 mL/sec, respectively. The times of these extravasation "alarms" corresponded to maximum extravasated volumes, respectively, of 4, 6.5, and 8 mL. Microwave radiometry has clinical potential for early detection of extravasation of contrast medium administered with power injectors.

Absolute ethanol embolization for peripheral arteriovenous malformation: report of two cures.

We have reported two patients in whom absolute ethanol was used to sclerose arteriovenous malformations. Because of its low viscosity, liquid form, and devastating effect when injected intra-arterially, absolute ethanol is effective in treating AVMs, and it has been proven to have curative potential. For these same reasons it is also potentially harmful, particularly to nerves and possibly to skin.

Characteristics of spinal cord compression in adenocarcinoma of prostate.

Of 611 patients with biopsy-proved adenocarcinoma of the prostate, spinal cord compression developed in 41 (6.7%) at a median interval of twenty-four months after primary diagnosis. Spinal cord involvement most often occurred in the thoracic area, with 95 per cent of patients showing radiographic evidence of osseous vertebral metastasis at the level of cord compression. All lesions but one were located extradurally, and patients with Stage D2 disease, by virtue of bony metastases, were therefore at greatest risk for development of neurologically compressive disease. There was also a significant increase in the incidence of spinal cord involvement among the more poorly differentiated tumors, although tumor histology did not appear to influence the median interval between vertebral metastasis and cord compromise. Survival following spinal cord involvement was relatively poor and unrelated to tumor differentiation. Forty-six per cent of patients survived less than six months and 20 per cent less than two months. The two most noteworthy survivors are alive at thirty and ninety-seven months, the latter after combined treatment for an intradural lesion.

The management of clotted angiographic catheters.

In our experience, clotted angiographic catheters pulled back to near the puncture site and severed near the skin will spontaneously clear, facilitating insertion of a guidewire and catheter exchange without repuncture or other manipulation.