Treatment with oral biphosphonates can increase the sensitivity of sestamibi radionuclide imaging in patients with primary hyperparathyroidism.

The sensitivity of 99mTc-sestamibi scan in detecting parathyroid disease in primary hyperparathyroidism (PHP) is almost 90%, and therefore facilitates successful parathyroidectomy. To enhance the diagnostic accuracy of the procedure, we repeated imaging with 99mTc-sestamibi in 15 patients with PHP and an initially negative (11 patients) or weakly positive (four patients) 99mTc-sestamibi scan after the administration of 10 mg of oral alendronate for 2 months. Serum calcium, phosphate and parathormone (PTH) measurements were obtained at presentation and after 1 and 2 months' treatment with alendronate. Eight patients with an initially negative 99mTc-sestamibi scan demonstrated at least one area of uptake in the repeated scan. Six of these patients underwent surgery and obtained a biochemical cure; a single adenoma was found in four and hyperplasia in the remaining two. In all four patients with an initially weakly positive 99mTc-sestamibi scan, the repeated scan demonstrated enhanced uptake and also revealed further areas of uptake. Two of these patients underwent surgery with a biochemical cure; an adenoma was found in one and hyperplasia in another. Compared with baseline there was a significant increase in PTH but not in calcium or phosphate levels during treatment with alendronate. We suggest that, in patients with PHP and a negative or weakly positive initial 99mTc-sestamibi scan, administration of oral alendronate may be associated with a positive repeated 99mTc-sestamibi scan and can thus enhance the sensitivity of the procedure.

Reverse of the differential uptake intensity of Tc-99m MIBI and Tc-99m V-DMSA by multiple myeloma lesions in response to therapy.

PURPOSE: The objective of this study was to compare the uptake changes of Tc-99m 2-methoxy isobutyl isonitrile (MIBI) and Tc-99m pentavalent dimercaptosuccinic acid (V-DMSA) in multiple myeloma (MM) lesions in response to high-dose chemotherapy (HDC). MATERIALS AND METHODS: The authors compared Tc-99m MIBI and Tc-99m V-DMSA scans before and after HDC in a patient with focal MM lesions without amyloidosis who had received previous standard chemotherapy as well. RESULTS: HDC had the effect of eliminating all Tc-99m MIBI uptake in the lesions. Tc-99m V-DMSA uptake was increased in lesions presenting significant initial Tc-99m MIBI uptake. In 1 particular lesion that demonstrated this phenomenon, magnetic resonance showed necrosis of the area of MM. CONCLUSION: The authors consider that the effect of increasing Tc-99m V-DMSA uptake in the absence of an increase in viable plasma cells possibly reflects the treatment-generated inflammatory and fibrotic changes and not necessarily viable tumor tissue. Exclusive focal Tc-99m V-DMSA uptake in this clinical setting could be considered as a sign of effectively treated lesions and not a sign of deterioration.

Effects of acute, transient coronary occlusion on global and regional right ventricular function in humans.

OBJECTIVES: The aim of this study was to investigate the changes in right ventricular function during acute coronary occlusion produced by inflating a coronary angioplasty balloon catheter. BACKGROUND: Alterations in right ventricular function are well known to occur in patients with acute myocardial infarction or ischemic cardiomyopathy. However, the changes in right ventricular function resulting from acute, transient coronary occlusion of each of the major coronary arteries have been scantily studied, perhaps because of serious limitations of currently available technology. METHODS: A newly designed, mobile, multiwire gamma camera, in combination with generator-produced tantalum-178, affords high count rate first-pass radionuclide angiography and is thus ideal for studying right ventricular function at the bedside. Accordingly, 46 patients underwent first-pass radionuclide angiography at baseline and during transient coronary occlusion induced by a coronary angioplasty balloon catheter. RESULTS: A significant, albeit modest, decrease in global right ventricular ejection fraction occurred during occlusion of the left anterior descending (from 42.9 +/- 9.3% to 39 +/- 8.7%, p < 0.05) and left circumflex (from 44 +/- 9.1% to 38.8 +/- 7.9%, p = 0.03) coronary arteries, but diagonal artery occlusion caused no significant change in right ventricular ejection fraction. Occlusion of the right coronary artery proximal (but not distal) to the acute marginal branch caused a significant decrease in right ventricular ejection fraction (from 42.6 +/- 4.7% to 35.7 +/- 7.2%, p < 0.01). Although occlusion of the left anterior descending, left circumflex and proximal right coronary arteries all caused significant deterioration in regional right ventricular function, only proximal right coronary occlusion caused right ventricular dilation (p < 0.005). CONCLUSIONS: Significant impairment of right ventricular function occurs during transient occlusion of the left anterior descending, left circumflex and proximal right coronary arteries, but only occlusion of the latter causes acute right ventricular dilation, probably as a result of ischemia.

Quantification of left ventricular performance during transient coronary occlusion at various anatomic sites in humans: a study using tantalum-178 and a multiwire gamma camera.

To study the functional significance of transient coronary occlusion on systolic and diastolic left ventricular function relative to the anatomic site of occlusion, first-pass radionuclide angiography with a mobile multiwire gamma camera using tantalum-178 (dose activity less than or equal to 84 mCi/elution) was performed in 46 patients undergoing balloon coronary angioplasty. First-pass images were acquired immediately before angioplasty and during the last 30 s of a 60-s balloon inflation in 23 left anterior descending arteries, 18 right coronary arteries, 8 circumflex arteries and 3 diagonal coronary arteries. Occlusion of the left anterior descending artery resulted in significant decreases in left ventricular ejection fraction (54.6 +/- 12.7% to 32.3 +/- 10.6%, p = 0.0001) and peak filling rate (2.48 +/- 0.68 to 1.75 +/- 0.64 end-diastolic volumes/s, p = 0.0001), accompanied by severe abnormalities in regional function and left ventricular dilation. Right coronary artery occlusion caused inferior hypokinesia, but did not significantly change left ventricular ejection fraction (48.5 +/- 12.4% vs. 45.8 +/- 12.5%, p = NS) or peak filling rate (2.05 +/- 0.81 vs. 2.09 +/- 0.81 end-diastolic volumes/s, p = NS). Circumflex artery occlusion resulted in mild wall motion deterioration and a borderline decrease in ejection fraction (54.7 +/- 11.4% to 50.5 +/- 12%, p = 0.057). Diagonal artery occlusion did not cause significant changes in left ventricular ejection fraction or filling rate. The decrease in left ventricular ejection fraction during coronary occlusion was 9 +/- 25% and 27 +/- 22%, respectively, in those arteries with and without collateral supply (p = 0.052). These data provide strong evidence for the critical importance of the left anterior descending artery and the secondary role of the other coronary arteries in maintaining global systolic and diastolic left ventricular function and suggest a protective role of collateral vessels during coronary occlusion.

Blood-pool radionuclide angiography in patients with a Novacor left ventricular assist device.

Blood-pool radionuclide angiography was used to investigate the left ventricular function in eight patients who received a Novacor assist device as a bridge-to-cardiac transplantation. Studies were performed during maximal and minimal tolerated assist device flows. The left ventricular ejection fraction, volumes, cardiac output, and the pump ejection fraction were computer-assessed. All patients had severe left ventricular dilation and hypokinesis before insertion of the assist device, with a mean ejection fraction of 18% +/- 4% which improved to 44% +/- 18% (p less than 0.01) during maximal assist device flows, but fell to 25% +/- 15% (p less than 0.01) during minimal flows. The ventricular volumes became normal at maximal assist device flow but increased significantly (p less than 0.05) during minimal flow. The pump was well visualized and had an ejection fraction of 82% +/- 7%. These data indicate that this assist device effectively unloads the left ventricle. The deterioration in ejection fraction following decrease in assist device flow is in keeping with the dependency of these patients on the device to sustain adequate hemodynamics.