Prognostic value of thallium-201 single-photon emission computed tomography for patients with multivessel coronary artery disease after revascularization (the Emory Angioplasty versus Surgery Trial [EAST]).

The aim of this study was to investigate the relation between reversible thallium single-photon emission computed tomography (SPECT) myocardial perfusion defects at 1-year after revascularization and quantitative indexes in Emory Angioplasty versus Surgery Trial (EAST) and outcomes 3 years after revascularization in 336 patients. EAST was a randomized controlled trial assessing cardiac outcomes for angioplasty versus bypass surgery for patients with multivessel coronary artery disease. During this prospective trial, a substudy included the evaluation of the prognostic value of reversible defects on quantitative thallium SPECT. At 1-year after revascularization, 336 patients underwent SPECT thallium-201 stress myocardial perfusion and 3-hour delayed imaging. Subsequent events, percutaneous transluminal coronary angioplasty, coronary artery bypass graft surgery, myocardial infarction, and death, were recorded at 3 years. A stress-induced reversible thallium-201 defect was defined using a quantitative index of a reversibility score >30% and severity score >500. Reversible defects were observed more frequently in the percutaneous transluminal coronary angioplasty than in the coronary artery bypass graft surgery treatment groups (46% vs 27%, p <0.001). A total of 123 patients had stress-induced, reversible thallium defects and more events than patients with other perfusion results (freedom from all events was 81.3% vs 94% [p <0.001], and freedom from myocardial infarction and death 88.3% vs 95.5% [p = 0.031]). Quantitative thallium SPECT at 1 year after revascularization risk stratifies patients as to their likelihood of major cardiac outcomes.

Reproducibility of thallium-201 exercise SPECT studies.

UNLABELLED: A detailed analysis of intrapatient reproducibility of exercise SPECT thallium studies is presented. METHODS: Twenty patients in stable condition were re-examined with exercise-redistribution SPECT201 Tl within 3-9 days without intervening procedures. At peak stress, 3.5 mCi 201Tl were given intravenously 1 min prior to exercise termination. SPECT imaging started at 5 and 180 min. Acquisition and processing protocols were the same for all studies. Coronary angiography was performed on 19 patients and showed coronary artery disease (CAD) in 18, and no CAD in one; one patient did not have coronary arteriography. RESULTS: For 16 of 20 patients, exercise levels and ECG were comparable for both studies. Ten patients reproduced ST-segment depression; two reproduced angina; one had left bundle branch block (LBBB) on both studies after 1 min of exercise. The remaining seven patients had no ECG changes or symptoms during exercise. Four of 20 (20%) thallium scans differed: three in degree of redistribution and one (5%) in presence of a second stress defect. In three of four patients whose thallium studies showed some nonreproducibility, there were differences in exercise. Thallium results were identical in 15 of 16 patients whose ECG/exercise tests were reproducible (94%). Interobserver agreement was 95%. CONCLUSION: There was excellent reproducibility of 201Tl SPECT scintigraphy in patients who reproduced exercise test performance and symptoms.

Hyperekplexia: report of a nonfamilial adult onset case associated with obstructive sleep apnea and abnormal brain nuclear tomography.

We report the unique occurrence of hyperekplexia and obstructive sleep apnea (OSA) in a 48-year-old male. Polysomnography and multiple sleep latency testing excluded cataplexy, which can be confused with startle attacks. A new imaging finding was a nuclear tomography abnormality in the left frontal lobe. We postulate that this finding may represent a functional cortical lesion of a descending pathway that normally inhibits the startle reflex. Serious complications of pharmacotherapy with clonazepam, the drug of choice for hyperekplexia, can be avoided by first evaluating for OSA.

Tc-99m DTPA and I-131 hippurate renography. Findings in hepatorenal syndrome.

Tc-99m DTPA and I-131 OIH renography were performed simultaneously in a patient with hepatorenal syndrome. Blood flow was delayed and diminished bilaterally; there was Tc-99m DTPA and I-131 OIH retention in the parenchyma with no evidence of tracer retention in the collecting systems. The I-131 OIH renogram curve demonstrated a steadily rising pattern, whereas the Tc-99m DTPA curve demonstrated an initial vascular peak and was subsequently flat. There was no appreciable response to furosemide. These findings are not specific for hepatorenal syndrome, and the diagnosis is based on the characteristic clinical setting and the exclusion of other causes of renal failure. A brief literature review and a discussion of differential diagnosis are included.

Comparison of Tc-99m MAG3 and Tc-99m DTPA in renal transplant patients with impaired renal function.

Tc-99m mercaptoacetyltriglycine (MAG3) is a new Tc-99m renal agent that compares favorably to I-131 Hippuran in animal models, normal volunteers, and patients. Based on the fact that Tc-99m MAG3 has a much more rapid clearance than Tc-99m DTPA and a smaller volume of distribution, it was postulated that the image quality of Tc-99m MAG3 studies should be superior to scans obtained using Tc-99m DTPA, particularly in patients with impaired renal function. To test this hypothesis, Tc-99m DTPA and MAG3 images were obtained in three transplant patients during periods of stable but impaired renal function. In one study, the Tc-99m DTPA study was potentially misleading, whereas the Tc-99m MAG3 examination assessed the clinical situation correctly. In all three cases, the Tc-99m MAG3 images were superior.

Clinical comparison of I-131 orthoiodohippurate and the kit formulation of Tc-99m mercaptoacetyltriglycine.

Previous studies in animals and humans have shown that technetium-99m mercaptoacetyltriglycine (MAG3) purified by high-performance liquid chromatography is a renal tubular agent with characteristics similar to those of iodine-131 orthoiodohippurate (OIH). A kit formulation for Tc-99m MAG3 has been developed and compared with I-131 OIH in 17 patients with suspected renal dysfunction and three potential kidney donors. There were no adverse reactions. Tc-99m MAG3 images were of good quality and consistently better than I-131 OIH images. There was no significant difference in the relative renal uptake of Tc-99m MAG3 and I-131 OIH. The 30-minute urinary excretion of Tc-99m MAG3 was 36.4%, versus 40.4% for I-131 OIH. The average plasma clearance of Tc-99m MAG3 (138 mL/min +/- 117) was less than that of I-131 OIH (272 mL/min +/- 205) (P less than .001); however, there was good correlation between the Tc-99m MAG3 and I-131 OIH clearances (r = .87). The volume of distribution of Tc-99m MAG3 (5.96 L +/- 1.94) was less than that of I-131 OIH (9.41 L +/- 3.73) (P less than .001). These characteristics and the advantages of a simple kit formulation should lead to widespread clinical use.

Ectopic parathyroid gland. Localization with thallium-201 SPECT.

Dual isotope Tl-201/Tc-99m subtraction is a useful technique for localization of abnormal parathyroid glands. A case of tomographic localization of nonsubtracted Tl-201 to a mediastinal parathyroid is reported and the possible benefit of this method discussed.

Crystallographic studies of bovine beta2-microglobulin.

Crystals of the bovine milk protein lactollin yield x-ray diffraction data extending to a resolution of 2.8 A. Lactollin is a bovine analogue of beta2-microglobulin, a protein that is homologous in amino acid sequence to the constant domains of immunoglobulins and is the light chain of the human and murine major histocompatability antigens. The protein crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 77.4, b = 47.9, and c = 34.3 A. The unit cell parameters and physical chemical solution studies indicate that the molecule exists in the crystal and in solution as a single polypeptide chain of 12,000 daltons.