[en] Published in summary form only

[en] Published in summary form only

[en] Aim: We evaluated the accuracy of combined BMIPP and sestamibi SPECT to detect residual viability in 18 patients with recent acute myocardial infarction and in 20 patients with severe chronic left ventricular dysfunction. The evolution of both global and segmental function at six-month follow-up was used as gold standard. Results: Function improved in most dysfunctional segments showing less BMIPP than sestamibi uptake (mismatching). A significant relationship was found between the number of mismatched segments and the improvement in cardiac function. In contrast, segments with matched defects contain only scar tissue. The predictive accuracy was similar in patients with acute (85%) and with chronic left ventricular dysfunction (90%). Conclusion: The additional information provided by BMIPP substantially increased the accuracy of sestamibi uptake alone and of low-dose dobutamine echocardiography to predict long-term functional outcome. (orig.)

[en] We have evaluated the biodistribution and metabolism of iodine-123-15-(p-iodophenyl)-3-R,S-methyl pentadecanoic acid (BMIPP) in the presence of increased lactate levels induced by short-term heavy exercise. Five healthy male subjects received 159 MBq (±13 MBq) ¹²³I-BMIPP at rest and a week later after they performed a maximal exercise test using a bicycle ergometer. Planar and tomographic images were obtained with a dual-head gamma camera up to 4 h after administration of the tracer. Multiple blood samples were taken at different time points for blood clearance, substrate concentration measurements and for HPLC analysis of metabolites. The exercise test did not alter plasma glucose and non-esterified fatty acid concentrations, but blood lactate increased from 1.12 mmol/l at rest to 9.26 mmol/l with maximal exercise. After exercise, BMIPP showed a significantly faster plasma clearance than at rest and the production of PIPA, the end metabolite of BMIPP oxidation, was reduced. Activity in the heart was similar after exercise and at rest on planar images 15 min after injection (4.83±0.50%ID vs 4.80±0.43%ID, P=NS), although the myocardium-to-cavity activity ratio, as determined on the SPET images 20 min after tracer injection, was slightly increased after the exercise test (4.20±0.63 vs 3.78±1.34 at rest, P=NS). Significantly increased activity was observed in a leg muscle region of interest after exercise (4.98±0.50%ID vs 3.93±0.44%ID at rest, P=0.02). Between early and late images, tracer washout from the myocardium increased from 20.72% at rest to 36.72% after exercise (P<0.05), but was unchanged for liver and leg muscles. The metabolic and physiological alterations induced by exercise do not degrade image quality of BMIPP scintigraphy. On the contrary, exercise-induced hyperlactatemia seems to enhance myocardium-to-cavity activity ratios on SPET images, although this effect does not reach statistical significance in this small group of normal subjects. These findings further support the robustness of BMIPP SPET in varied metabolic environments. (orig.)

[en] Short communication

[en] The present study was set up (1) to investigate the potential occurrence of mismatches between β-methyl-iodophenyl pentadecanoic acid (BMIPP), a fatty acid analogue, and Sestamibi, and to describe their nature, and (2) to relate these mismatches to clinical characteristics such as whether or not thrombolysis or percutaneous transluminal coronary angioplasty (PTCA) had been performed. Twenty-six patients were studied within 2 weeks after myocardial infarction. Sestamibi and BMIPP single-photon emission tomography (SPET) were performed within 4 days of one another. Activity of both tracers was scored in 16 basal, 16 midventricular and 8 apical segments, using a four-point grading system: 3 = normal (≥ 65% of maximum activity), 2 = mildly decreased (45%-64%), 1 = moderately decreased (25%-44%), 0 = severely decreased (0%-24%). Coronary arteriography was obtained during the same hospital stay. Four hundred and seventy-seven segments out of 1040 studied were abnormal for at least one tracer: 197 with higher Sestamibi activity (group I), 226 with equal scores for Sestamibi and BMIPP (group II) and 54 with higher BMIPP activity (group III). Seventy-five percent of group I segments and 84% of group III segments were found in infarct-related artery territories. Group I segments were associated with acute thrombolysis and/or PTCA, and with the absence of prior infarction in the territory of the infarct-related artery. Group III segments were associated with the absence of thrombolysis or PTCA, with occlusion of the infarct-related artery, with previous infarction in the same territory and with a- or dyskinesia in this territory. (orig./MG)

[en] Dual-isotope studies with technetium-99m and iodine-123 may be useful for various organs, including brain and myocardium. For the images obtained with each of the tracers to be comparable, it is important that activity ratios (activity in one part of the image/reference activity in the image) are preserved by the imaging method. We have used a Rollo phantom to study how collimator response affects such ratios. All investigations were performed with ¹²³I(p, 5n) and on a Siemens Orbiter 3700 camera fitted with either a low-energy high-resolution (LEHR) or a medium-energy (ME) collimator. Images were made of a Rollo phantom filled with an aqueous solution of either ⁹⁹Tc or ¹²³I, and placed on the collimator surface with 8 cm of methyl-methacrylate interposed. Count densities were measured in ROIs drawn in each cell of the phantom, and normalised to the maximal ROI value in the image. The mean square error (MSE) was used to assess how well the ratios of count densities approximated the known activity ratios based on the dimensions of the cells of the phantom. For ^99mTc, regardless of the collimator used, the count density ratios approximated the activity ratios fairly well (LEHR: MSE=0.008; ME: MSE=0.020). for ¹²³I, count density ratios obtained with the LEHR were consistently higher than activity ratios (MSE=0.235), whereas the differences between the measured and the theoretical values were less with the ME collimator (MSE=0.013). Contrast fidelity of the ¹²³I images obtained with the LEHR collimator could be improved with Jaszczak scatter correction with k=1, but this led to unfavourable signal-to-noise ratios. For sequential ^99mTc/¹²³I studies with extended sources, ME is to be preferred because of its higher contrast accuracy. (orig./VHE)