Tc-99m Sestamibi Study Research Articles

Accuracy of 18F-Fluorocholine PET for the Detection of Parathyroid Adenomas: Prospective Single-Center Study.

The purpose of this prospective study was to determine the correct localization rate (CLR) of 18F-fluorocholine PET for the detection of parathyroid adenomas in comparison to 99mTc-sestamibi imaging. Methods: This was a single-arm prospective trial. Ninety-eight patients with biochemical evidence of primary hyperparathyroidism were imaged before parathyroidectomy using 18F-fluorocholine PET/MRI. 99mTc-sestamibi imaging performed separately from the study was evaluated for comparison. The primary endpoint of the study was the CLR on a patient level. Each imaging study was interpreted by 3 masked readers on a per-region basis. Lesions were validated by histopathologic analysis of surgical specimens. Results: Of the 98 patients who underwent 18F-fluorocholine PET, 77 subsequently underwent parathyroidectomy and 60 of those had 99mTc-sestamibi imaging. For 18F-fluorocholine PET in patients who underwent parathyroidectomy, the CLR based on the masked reader consensus was 75% (95% CI, 0.63-0.82). In patients who underwent surgery and had an available 99mTc-sestamibi study, the CLR increased from 17% (95% CI, 0.10-0.27) for 99mTc-sestamibi imaging to 70% (95% CI, 0.59-0.79) for 18F-fluorocholine PET. Conclusion: In this prospective study using masked readers, the CLR for 18F-fluorocholine PET was 75%. In patients with a paired 99mTc-sestamibi study, the use of 18F-fluorocholine PET increased the CLR from 17% to 70%. 18F-fluorocholine PET is a superior imaging modality for the localization of parathyroid adenomas.

Role of scintimammography in assessing the response of neoadjuvant chemotherapy in locally advanced breast cancer.

Locally advanced breast cancer (LABC) is a common cancer in the developing countries. Neoadjuvant chemotherapy (NACT) is a very important step in the treatment of such tumors and hence that the disease can be down staged and made amenable for surgery. All the tumors do not respond to the therapy equally. Hence, it becomes very important to predict the response of chemotherapy in such cases. This study evaluated the role of scintimammography in assessing the response to NACT in 23 patients with LABC. Histologically proven 23 patients of LABC were recruited in this study. Prechemotherapy tumor size was measured clinically in all patients and technitium (Tc)-99m sestamibi test was performed before NACT for each patient. Early (10 min) and delayed (2 h) image of the breast were acquired in anterior and lateral views after Tc-99m sestamibi intravenous injections and wash out rate (WOR) was computed. After 3-4 cycles of chemotherapy, surgery in the form of modified radical mastectomy was performed in 20 out of 23 patients (3 patients lost to follow-up) with pathologic evaluation of the residual tumor size. The pretherapy Tc-99m sestamibi WOR ranged from 8.3% to 68% with mean ± SD of 34.5% ±16.5%. The prechemotherapy Tc-99m sestamibi study predicted chemoresistance (WOR >45%) in 6 out of 20 patients and no chemoresistance (WOR <45%) in 14 out of 20 patients. When the WOR cut-off was set at >45%, the predictivity of the test was indicated by sensitivity of 91.7%, specificity of 62.5%, positive predictive value of 78.6%, and negative predictive value of 82.3% with a likelihood ratio of 0.1. Tc-99m sestamibi WOR is a reliable test for predicting tumor response to NACT. WOR >45% is highly predictive of chemoresistance with likelihood ratio of 0.1 than WOR <45% being predictive of chemoresponsiveness.

Non‐localizing Parathyroid Adenomas: Radiologic Error or True Entity

Objectives: Investigate radiographic assessment of non-localizing parathyroid adenomas (NLPA). Our goal was to determine whether non-localization is a result of radiologic interpretive error, or truly representative of non-visible parathyroid adenoma. Methods: We performed a retrospective chart review of 364 patients who underwent parathyroidectomy over a 5-year period. Thirty patients who were identified as having NLPA on pre-operative imaging were included. All available patient images were re-reviewed by two senior radiologists. Both readers were blinded to surgical outcomes and adenoma location on the first read of the imaging studies. Surgical outcomes were then revealed and the imaging was re-reviewed. The two reader’s results were subsequently compared for inter-reader reliability using Cohen’s kappa test. Results: All 30 patients with NLPA had pre-operative 99mTc sestamibi imaging available and 18 also had an ultrasound performed. Adenomas were identified intra-operatively and removed in all cases. Twenty-nine of the thirty (97%) 99mTc sestamibi studies were scored by the two readers as either negative or equivocal. There was excellent inter-observer agreement between the readers, with a kappa value of 0.706. For the ultrasound studies, however, the two readers’ inter-observer agreement was only fair, with a kappa value of 0.351. Conclusions: The inter-reader agreement in our series supports the conclusion that, for a sub-population of patients with parathyroid adenoma, pre-operative imaging will be truly negative/non-localizing.

Quantification of diagnostic accuracy using nitrate enhanced Tc-99m sestamibi gated myocardial SPECT in assessing myocardial viability: prospective analysis

The aim of this prospective study was to assess myocardial viability with nitrate-enhanced Tc-99m sestamibi gated single-photon emission computed tomography in patients with known coronary artery disease. We enrolled 48 consecutive patients (39 men, 9 women) aged 24-82 years, with coronary artery disease and history of myocardial infarction. A Tc-99m sestamibi study was conducted at rest as baseline, followed by a nitrate-enhanced study the next day. Of 960 segments analyzed, 244 of 480 in the left anterior descending coronary artery territory showed viability on the baseline study, and 276 were viable according to the nitrate-enhanced study. Similarly, of 192 right coronary segments analyzed, 148 showed viability on the baseline study compared to 153 on the nitrate study. Of 288 left circumflex territory segments analyzed, 206 showed viability on the baseline study compared to 241 on the nitrate study. The overall improvement of viability with the nitrate study was 12.04%. On the gated studies, the overall improvement with nitrate was 2.02%. The gated study also allowed grading of wall motion and thickness. It was concluded that nitrate-augmented Tc-99m sestamibi myocardial imaging significantly improved the detection of hibernating myocardium, with gated images further improving the accuracy of detection in borderline cases.

Exanthema after a stress Tc-99m sestamibi study: continue with a rest sestamibi study?

A mild allergic reaction assumed to be caused by injection of Tc-99m sestamibi for a stress myocardial perfusion imaging (MPI) is presented. We want to discuss the risk involved in completing the MPI with another sestamibi injection, and the precautions and possible treatment in case of a further reaction. A patient experienced a maculo-papular exanthema, i.e. a mild, probably allergic, adverse event (AE) after a stress MPI including administration of a dose of Tc-99m sestamibi. A rest MPI was needed to decide whether coronary bypass surgery should be performed. After prophylactic treatment with antihistamine and corticosteroid, an uneventful rest MPI was performed. International recommendations or guidelines related to treatment of AEs after nuclear medicine studies do not exist. Serious AEs in nuclear medicine are very rare, but anaphylactic reactions have been reported and may be life threatening. If repeated administration of the radio-pharmaceutical must be given, the prophylactic and therapeutic interventions should follow general international guidelines for allergic reactions.

Investigation of Respiratory Gating in Quantitative Myocardial SPECT.

The purpose of this study is to investigate optimal respiratory gating schemes using different numbers of gates and placements within the respiratory cycle for reduction of respiratory motion (RM) artifacts in myocardial SPECT. The 4D NCAT phantom with its realistic respiratory model was used to generate 96 3D phantoms equally spaced over a complete respiratory cycle modeling the activity distribution from a typical Tc-99m Sestamibi study with the maximum movement of the diaphragm set at 2 cm. The 96 time frames were grouped to simulate various gating schemes (1, 3, 6, and 8 equally spaced gates) and different placements of the gates within a respiratory cycle. Projection data, including effects of attenuation, collimator-detector response and scatter, from each respiratory gate and each gating scheme were generated and reconstructed using the OS-EM algorithm with correction for attenuation. Attenuation correction was done with average attenuation maps for each gate and over the entire respiratory cycle. Bull's-eye polar plots generated from the reconstructed images for each gate were analyzed and compared to assess the effect of RM. RM artifacts were found to be reduced the most when going from the ungated to the gated case. No significant difference was found in attenuation compensated images between the use of gated and average attenuation maps. Our results indicate that the extent of RM artifacts is dependent on the placement of the gates in a gating scheme. Artifacts are less prominent in gates near end-expiration and more prominent near end-inspiration. This dependence on gate placement decreases when going to higher numbers of gates (6 and higher). However, it is possible to devise a non-uniform time interval gating scheme with 3 gates that will produce results similar to those using a higher number of gates. We conclude that respiratory gating is an effective way to reduce RM artifacts. Effective implementation of respiratory gating to further improve quantitative myocardial SPECT requires optimization of the gating scheme based on the amount of respiratory motion of the heart during each gate and the placement of the gates within the respiratory cycle.

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Comparison of cardiac MR and 99mtc Sestamibi Spect in the evaluation of myocardial perfusion and viability in coronary artery disease

AbstractObjective - The present study was designed to compare the role of 99mTc sestamibi sciintigraphy (SPECT) and cardiac MR (CMR) in the detection of viable myocardium and to delineate myocardial scar tissue in patients with established chronic ischemic heart disease. Methods - Thirty six patients with established chronic ischemic heart disease on coronary angiograms which was the gold standard underwent both stress CMR and 99mTc sestamibi studies. Out of these 11 patients who had reduced end diastolic thickness &lt; 5.5mm alongwith wall motion abnormalities also underwent dobutamine MR (DMR) for determining the contractile myocardial reserve. Results- Both CMR and SPECT showed a good correlation in the detection of perfusion defects (r=0.89) with the diagnostic region of operating characteristics being 0.97. The sensitivity and specificity of SPECT to detect perfusion defects were 82.6% and 90.4% respectively. In comparison CMR had a sensitivity, specificity of 92.8% and 98.2% respectively in identifying such defects.It was also superior in defining transmural infarcts(TMI) with sensitivity being 100% vs 79.3% of SPECT (p=&lt; 0.0001) and all the 10 segments with TMI showed irreversible myocardial dysfunction on DMR. This was the only imaging parameter that indicated myocardial non viability with a specificity of 100%. Conclusions - CMR is a useful diagnostic tool in the evaluation of patients with chronic myocardial ischemia and is superior to SPECT in the detection and quantification of myocardial infarctions. Demonstration of a TMI on CMR is a finding strongly associated with non viability of the myocardium and may preclude the need for doing a DMR in such cases.

???Shine Through??? on Dual Tracer Parathyroid Scintigraphy: A Potential Pitfall in Interpretation

Dual tracer scintigraphy has become the procedure of choice for preoperative localization of parathyroid adenomas. The typical protocol used by most laboratories is to initially perform a Tc-99m sestamibi (MIBI) study with early and delayed (2-3 hours) washout phase images. This is followed by a thyroid-specific Tc-99m pertechnetate study. A potential pitfall exists if the delayed phase of the initial MIBI study shows an intense, abnormal focus of retention. This focus may interfere with interpretation of the subsequent pertechnetate study because of a "shine through" effect. To differentiate a parathyroid adenoma from a thyroid adenoma, it may be necessary to repeat the thyroid-specific pertechnetate scan on a separate day after the dual tracer study.

Acute beta-blockade reduces the extent and severity of myocardial perfusion defects with dipyridamole Tc-99m sestamibi SPECT imaging

ObjectivesThe goal of this study was to examine the effect of acute beta-blockade on dipyridamole Tc-99m sestamibi myocardial perfusion imaging (DMPI). BackgroundStudies suggest that antianginal drugs may reduce the presence and severity of myocardial perfusion defects with dipyridamole stress. However, there are no data regarding specific drugs. MethodsPatients with catheterization-proven coronary artery disease (CAD) were enrolled in this prospective, double-blind, placebo-controlled study and randomly assigned to DMPI after placebo, low-dose metoprolol (up to 10 mg), and high-dose metoprolol (up to 20 mg). Patients underwent one Tc-99m sestamibi study at rest on a separate day. The interval between DMPI studies was ≤14 days. Images were interpreted by three observers blinded to clinical data using a 17-segment, five-point model. For each image, a summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) were calculated (SDS = SSS − SRS). Images with an SSS <4 were considered normal. ResultsTwenty-one patients completed all four Tc-99m sestamibi studies. The sensitivity of DMPI for detection of CAD was 85.7% with placebo versus 71.4% with low- and high-dose metoprolol. In comparison with placebo, the SSS was significantly lower (p < 0.05) with low- and high-dose metoprolol (12.0 ± 10.1 vs. 8.7 ± 9.0 and 9.3 ± 10.6, respectively). The SDS also was significantly lower (8.4 ± 8.8 with placebo vs. 5.0 ± 6.7 [p < 0.001] and 5.4 ± 7.9 [p < 0.01] with low- and high-dose metoprolol, respectively). ConclusionsThe presence and severity of CAD may be underestimated in patients receiving beta-blocker therapy undergoing dipyridamole stress myocardial perfusion imaging.

Incremental value of exercise technetium-99m tetrofosmin myocardial perfusion single-photon emission computed tomography for the prediction of cardiac events

This study assessed the incremental prognostic implications of normal and equivocal exercise technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) and sought to determine its incremental prognostic value, impact on patient management and cost implications.The prognostic implications of Tc-99m sestamibi SPECT are not well defined, and risk stratification using this test has not been explored.We studied 1,702 patients referred for exercise Tc99m sestamibi SPECT who were followed up for a mean (±SD) of 20 ± 5 months. Patients with previous percutaneous transluminal coronary angioplasty or coronary artery bypass surgery were excluded. The SPECT studies were assessed using semiquantitative visual analysis. Cardiac death and myocardial infarction were considered “hard” events, and coronary angioplasty and bypass surgery >60 days after testing were considered “soft” events.Of the 1,702 patients studied, 1,131 had normal or equivocal scan results. A total of 10 events occurred in this group (1 cardiac death and 1 myocardial infarction [0.2% hard events]; 4 coronary angioplasty and 4 bypass surgery procedures [0.7% soft events]). The rates of hard events and referral to catheterization after SPECT were similarly low in patients with a low (< 0.15), intermediate (0.15 to 0.85) and high (>0.85) post-exercise treadmill test (ETT) likelihood of coronary artery disease. With respect to scan type, patients with normal, probably normal or equivocal scan results had similarly low hard event rates. In the 571 patients with abnormal scan results, there were 43 hard events (7.5%) and 42 soft events (7.4%) (p < 0.001 vs. 1,131 patients with normal scan results for both). When the complete spectrum of scan responses was considered, SPECT provided incremental prognostic value in all patient subgroups analyzed. However, the nuclear scan was cost-effective only in patients with interpretable exercise ECG responses and an intermediate to high post-ETT likelihood of coronary artery disease and in those with uninterpretable exercise ECG responses and an intermediate to high pre-ETT likelihood of coronary artery disease.Normal or equivocal exercise Tc-99m sestamibi study results are associated with a benign prognosis, even in patients with a high likelihood of coronary artery disease. Although incremental prognostic value is added by nuclear testing in all patient subgroups, a testing strategy incorporating nuclear testing proved to be cost-effective only in the groups with an intermediate to high likelihood of coronary artery disease before scanning.

Influence of patient height and weight and type of stress on myocardial count density during SPECT imaging with thallium-201 and technetium 99msestamibi

Background. The aim of this study was to determine the variability in myocardial activity with 99mTc-labeled sestamibi and 201T1 tomographic imaging, and to correlate this variability with patient anthropometric data and type of stress. Methods and Results. Conventional tomographic acquisition (all-purpose collimator, 30 views, 40 sec/view) was performed in 249 patients (155 with 99mTc-sestamibi, 84 with 201T1). Normal myocardium was identified in three short-axis tomographic slices between the base and mid-ventricle. To exclude abnormal myocardium, all myocardial activity below an 85% threshold of peak counts was excluded. The average counts per pixel in the remaining myocardium was determined. All data were normalized to a collimator sensitivity of 8.1 counts/min/kBq and corrected for decay. Myocardial count densities in both 201T1 and 99mTc-sestamibi studies exhibited a high degree of variability and varied by factors of 3 to 4 and 2.5 to 3 respectively, between the 10th and 90th percentile of count densities. All 99mTc-sestamibi studies showed an inverse correlation ( R ∼ 0.7) between myocardial count density and patient weight. For stress 201T1 studies in male patients, a similar inverse correlation ( R = 0.63) was found between patient weight and myocardial count density. No correlation was found for female patients. For rest 99mTc-sestamibi studies, the average myocardial count density was 1245 ± 297 counts/pixel for a 1.11 GBq (30 mCi) injection. This was similar with pharmacologic stress (1224 ± 297 counts/pixel per 1.11 GBq (30 mCi), but significantly higher with exercise (1569 ± 363 counts/pixel per 1.11 GBq (30 mCi) ( p < 0.005).201Tl studies averaged 327 ± 97 counts/pixel (111 MBq [3mci]injection) with exercise and 374 ± 145 counts/pixel/111 MBq (3 mCi) with pharmacologic stress ( p = NS). Redistribution studies after exercise/pharmacologic stress (with a 37 MBq [1 mci]reinjection) averaged 267 ± 83 counts/pixel (148 MBq [3+1 mci]) . Conclusions. Measured count densities in the myocardium demonstrate a high degree of variability that is only weakly correlated with patient anthropometric data. Nevertheless, knowledge of the mean values of myocardial activity as a function of administered dose may be useful in the optimization of rapid imaging procedures for 99mTc-based perfusion agents.

Sestamibi uptake in brown tumor simulating a lung mass.

A 28-year-old man with severe secondary hyperparathy-roidism and on hemodialysis for 11 years underwent a Tc-99m sestamibi study for preoperative localization of hyperfunctioning parathyroid glands. Laboratory data included a serum calcium of 10.8 mg/100 mL and a parathormone level of 1722 pg/mL. There were no palpable neck masses. In addition to bilateral localization of hyperplastic parathyroid glands, the scintigram showed an intense focus of uptake in the left hemithorax, suggesting a lung mass. Radiographic correlation revealed the MIBI uptake to be in a large expansile lytic lesion of the second rib consistent with a brown tumor.

The role of nuclear medicine in primary bone and soft tissue tumors

Although there is a limited role initially for staging the disease of primary bone and soft tissue tumors and for differentiation of benign from malignant lesions, nuclear medicine studies are recommended before starting treatment. A total body bone scan that includes a three phase study for the involved region helps to outline the vascularity of the lesion and both soft tissue and bony involvement, as well as involvement of other bones. A thallium 201 chloride or technitium 99m methoxy isobutyl isonitrile (SestaMIBI) tumor imaging study is recommended for baseline study and for future reference to evaluate the response to preoperative chemotherapy. This is of special importance to determine whether the patient needs an amputation or a limb-salvaging procedure. A follow-up thallium or 99mTc sesta MIBI study is not recommended early after surgery. A waiting period of at least 2 months is essential to avoid false-positive uptake caused by postoperative changes although this could be differentiated by comparing the ratios of lesion uptake in both early and delayed thallium imaging and with the ratios from the blood pool phase of the bone scan. Persistent thallium uptake in delayed images accompanied by ratios that are higher than the blood pool ratios is highly indicative of early recurrence. In the future, F-18 FDG tumor imaging acquired either on dedicated positron-emission tomography (PET) systems or by using a dual head gamma camera for coincidence detection will replace thallium and 99mTc sesta MIBI in those centers that have access to this technology. This is especially important at sites where thallium and MIBI have limitations because of normal uptake in adjacent organs.

Muscular uptake of Tc-99m sestamibi showing collateral flow in a case of venous thrombosis.

A 70-year-old man had preoperative cardiac evaluation prior to a Whipple procedure for pancreatic carcinoma. A resting Tc-99m sestamibi study showed obstruction of the left brachiocephalic vein. The radiopharmaceutical eventually reached the heart, but extraction of a portion of the Tc-99m sestamibi occurred in muscles of the left arm and chest wall, which provided indirect, static documentation of collateral flow. This observation of signal amplification may provide a new basis for performing radionuclide venography in cases of suspected deep vein thrombosis.

Segmentation of the body and lungs from Compton scatter and photopeak window data in SPECT: a Monte-Carlo investigation

In SPECT imaging of the chest, nonuniform attenuation correction requires use of a patient specific attenuation (mu) map. Such a map can be obtained by estimating the regions of (1) the lungs and (2) the soft tissues and bones, and then assigning an appropriate value of attenuation coefficient (mu) to each region. The authors proposed a method to segment such regions from the Compton scatter and photopeak window SPECT slices of Tc-99m Sestamibi studies. The Compton scatter slices are used to segment the body outline and to estimate the regions of the lungs. Locations of the back bone and sternum are estimated from the photopeak window slices to assist in the segmentation. To investigate the accuracy of using Compton scatter slices in estimating the regions of the body and the lungs, a Monte-Carlo SPECT simulation of an anthropomorphic phantom with an activity distribution and noise characteristics similar to patient data was conducted. Energy windows of various widths were simulated for use in locating a suitable Compton scatter window for imaging, The effects of attenuation correction using a mu map based on segmentation were also studied. The results demonstrated for the activity and mu maps studied herein that: (1) reasonable contrast could be obtained from Compton scatter data for the segmentation of the lung regions, (2) true positive rates of 99% and 89% for determining the body and lung regions, respectively, with total error rates of 4% and 29%, could be achieved, (3) usage of a mu map based on segmentation for attenuation correction improved relative quantification over filtered backprojection, (4) variations in the assigned mu value of 40% smaller or 40% larger in the lung regions had an insignificant impact on the results of relative quantification, (5) a wide energy window away from the photopeak window for recording scattered events could benefit both the segmentation of the lung regions and the attenuation correction of the activity in the myocardium region, and (6) usage of a smaller than true mu value in the lung regions of an assigned mu map might benefit attenuation correction for absolute quantification.

Hyperparathyroidism in high-risk surgical patients: evaluation with double-phase technetium-99m sestamibi imaging.

To evaluate the accuracy of technetium-99m sestamibi as a single agent in the detection and localization of hyperfunctioning parathyroid tissue in patients who underwent prior neck exploration or who otherwise are high surgical risks. Thirty-nine patients with hyperparathyroidism underwent 40 double-phase Tc-99m sestamibi studies. Histopathologic correlation was obtained for all studies. Thirty patients had solitary adenomas, and nine had hyperplastic glands. One developed recurrent hypercalcemia after five-gland resection and underwent repeat imaging and operation. Double-phase sestamibi imaging prospectively enabled localization of 46 (77%) of 60 abnormal glands. Twenty-eight (93%) of 30 adenomas were correctly localized, whereas 18 (60%) of 30 hyperplastic glands were localized. The overall specificity of the study was 98% with one false-positive study. Gland weight and vascularity were statistically significant predictors of uptake of sestamibi. Double-phase Tc-99m sestamibi imaging is a promising technique for localization of parathyroid adenomas in high-risk surgical patients. Localization of multiple hyperplastic glands remains a challenge.

Incremental value of prognostic testing in patients with known or suspected ischemic heart disease: A basis for optimal utilization of exercise technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography

This study assessed the incremental prognostic implications of normal and equivocal exercise technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) and sought to determine its incremental prognostic value, impact on patient management and cost implications. The prognostic implications of Tc-99m sestamibi SPECT are not well defined, and risk stratification using this test has not been explored. We studied 1,702 patients referred for exercise Tc-99m sestamibi SPECT who were followed up for a mean (+/- SD) of 20 +/- 5 months. Patients with previous percutaneous transluminal coronary angioplasty or coronary artery bypass surgery were excluded. The SPECT studies were assessed using semiquantitative visual analysis. Cardiac death and myocardial infarction were considered "hard" events, and coronary angioplasty and bypass surgery > 60 days after testing were considered "soft" events. Of the 1,702 patients studied, 1,131 had normal or equivocal scan results. A total of 10 events occurred in this group (1 cardiac death and 1 myocardial infarction [0.2% hard events]; 4 coronary angioplasty and 4 bypass surgery procedures [0.7% soft events]). The rates of hard events and referral to catheterization after SPECT were similarly low in patients with a low (< 0.15), intermediate (0.15 to 0.85) and high (> 0.85) post-exercise treadmill test (ETT) likelihood of coronary artery disease. With respect to scan type, patients with normal, probably normal or equivocal scan results had similarly low hard event rates. In the 571 patients with abnormal scan results, there were 43 hard events (7.5%) and 42 soft events (7.4%) (p < 0.001 vs. 1,131 patients with normal scan results for both). When the complete spectrum of scan responses was considered, SPECT provided incremental prognostic value in all patient subgroups analyzed. However, the nuclear scan was cost-effective only in patients with interpretable exercise ECG responses and an intermediate to high post-ETT likelihood of coronary artery disease and in those with uninterpretable exercise ECG responses and an intermediate to high pre-ETT likelihood of coronary artery disease. Normal or equivocal exercise Tc-99m sestamibi study results are associated with a benign prognosis, even in patients with a high likelihood of coronary artery disease. Although incremental prognostic value is added by nuclear testing in all patient subgroups, a testing strategy incorporating nuclear testing proved to be cost-effective only in the groups with an intermediate to high likelihood of coronary artery disease before scanning.

Use of Tc-99m sestamibi infusion for detection of hibernating myocardium. A preliminary report.

To evaluate whether a prolonged infusion of Tc-99m sestamibi allows for visualization of viable myocardium in areas of hypoperfused myocardium, 25 patients were prospectively studied. Each patient was imaged four times in two consecutive days in the following manner: day 1:1) immediately after injection of Tl-201 at rest, 2) 1 hour after a bolus injection of Tc-99m sestamibi at rest; and day 2: 1) imaging in the Tl-201 window for 24 hour redistribution, 2) imaging after a 1-hour infusion of Tc-99m sestamibi. The two Tc-99m sestamibi and two Tl-201 studies were evaluated for presence of redistribution. This was present both on the Tl-201 and Tc-99m sestamibi studies (concordant) in 13 cases, and absent on both the Tl-201 and Tc-99m sestamibi studies (concordant) in 9 cases. In two cases redistribution was seen on the Tl-201 images only, and in one case it was seen on the Tc-99m sestamibi images only (discordant). Tc-99m sestamibi infusion may provide information about the presence of viable myocardium which is similar to that provided by Tl-201 24-hour imaging.

Evaluation of hypoperfusion at lateral wall in hypertensive patients with TL201 and Tc99m sestamibi studies

Evaluation of hypoperfusion at lateral wall in hypertensive patients with TL201 and Tc99m sestamibi studies