Accuracy of SPECT thallium studies in a community hospital.

The present study shows an overall accuracy to the Cedars-Sinai trial on a patient and a combined vascular territory basis. These results suggest SPECT thallium studies can provide information despite the referral biases and unselected patient population inherent in a busy clinical practice.

The correlation between three methods of skin perfusion pressure measurement: radionuclide washout, laser Doppler flow, and photoplethysmography.

The most accurate measurement of skin perfusion pressure is made with use of radioisotopic clearance techniques. We compared the skin perfusion pressure using radioisotope to the skin perfusion pressure measured simultaneously by placing laser Doppler and photoplethysmography probes within a transparent polyvinylchloride plastic blood pressure cuff in 13 subjects. A new device, which was created for this experiment, consisted of a plastic bladder into which light-emitting probes can be placed, so that the pressure applied to the skin was transmitted by the surface of the bladder, rather than by the surface of a rigid probe. The cuff was inflated to a supra-systolic pressure over the intradermal injection site of technetium Tc 99m, then deflated in 10 mm Hg decrements at 3-minute intervals. The pressures at which radioisotope clearance began, at which microcirculatory flow was detected by laser Doppler, and at which deflection of the photoplethysmography (DC mode) output occurred, were recorded as the skin perfusion pressure. The range of radioisotopic determined skin perfusion pressure was 0 to 100; skin perfusion pressure-laser Doppler was 0 to 100; and skin perfusion pressure-photoplethysmography was 60 to 100, with 7 of 13 limbs demonstrating no clear deflection point and thus an unobtainable skin perfusion pressure-photoplethysmography reading. Linear regression revealed a coefficient of correlation of 0.991 for skin perfusion pressure when the radioisotopic and laser Doppler methods were compared. Our study is not in agreement with previous reports of the successful determination of skin perfusion pressure with use of photoplethysmography. This may be due to differences in our technique when compared with previous reports of skin perfusion pressure-photoplethysmography determination.(ABSTRACT TRUNCATED AT 250 WORDS)

SPECT anti-CEA monoclonal antibody detection of occult colorectal carcinoma metastases.

Radioimmunodetection (RAID) using Tc-99m labeled Fab' fragments of the anti-CEA monoclonal antibody IMMU-4 was performed in a 68-year-old man for preoperative evaluation of colonic metastases. Planar images at 3 and 18 hours showed uptake within known metastases in the left lobe of the liver that had been observed with CT and at surgery during the preceding month. SPECT images at 3 hours demonstrated two additional unsuspected lesions. All sites were surgically confirmed the following day using intraoperative sonographic guidance, with the smallest occult lesion measuring only 6 x 9 mm. This case illustrates the limitations of CT and surgery, the potential of RAID for the detection of occult metastases, the increased sensitivity of SPECT over planar images for detecting lesions less than 1 cm in diameter, and the value of intraoperative guidance for small nonpalpable lesions.