Technetium 99m-labeled Sestamibi Research Articles

Association of Posttraumatic Stress Disorder With Mental Stress–Induced Myocardial Ischemia in Adults After Myocardial Infarction

Posttraumatic stress disorder (PTSD) is prevalent among patients who survived an acute coronary syndrome and is associated with adverse outcomes, but the mechanisms underlying these associations are unclear. To evaluate the association of PTSD with mental stress-induced myocardial ischemia among individuals who survived a myocardial infarction (MI). This cross-sectional study included 303 patients aged 18 to 60 years enrolled from a university-affiliated network. Participants had a verified history of MI within 8 months. Data were collected from June 2011 to March 2016, and data analysis was conducted from March to June 2019. A clinical diagnosis of PTSD (lifetime and current) was obtained using the Structured Clinical Interview from the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition), and PTSD symptom subscales were assessed with the civilian version of the PTSD Symptom Checklist. Patients received technetium 99m-labeled sestamibi myocardial perfusion imaging at rest, with mental stress (ie, a speech task) and conventional stress (ie, exercise or pharmacologic). A summed difference score (ie, the difference between stress and rest scores) was used to assess ischemia under both stress conditions. Among 303 participants (148 [48.8%] women; 198 [65.3%] African American; mean [SD] age, 51 [7] years), the prevalence of PTSD was 14.5% (44 patients). Patients with PTSD had a higher rate of ischemia with mental stress than those without PTSD (12 of 44 [27.3%] vs 38 of 259 [14.7%]; P = .04) and more than twice the mean number of ischemic segments (1.2 [95% CI, 0.5-1.8] vs 0.5 [95% CI, 0.3-0.7]; P < .001), but there was no difference in conventional stress ischemia (10 of 44 [22.7%] vs 60 of 259 [23.2%]; P = .91). Increasing levels of PTSD symptoms were associated with higher odds of ischemia with mental stress (adjusted odds ratio [OR] per 5-point score increase, 1.18; 95% CI 1.04-1.35; P = .01) but not with conventional stress (adjusted OR per 5-point score increase, 1.05; 95% CI, 0.92-1.21; P = .47). Reexperiencing trauma was the symptom cluster most robustly associated with the presence of ischemia with mental stress (adjusted OR per 5-point score increase, 1.87; 95% CI 1.21-2.91; P = .005), followed by avoidance and numbing (adjusted OR per 5-point score increase, 1.51; 95% CI, 1.07-2.14; P = .02). In this study of young and middle-aged individuals with MI, with a large representation of women and patients from racial/ethnic minority groups, PTSD was associated with the development of myocardial ischemia with mental stress. A higher ischemic response to mental stress represents a potential pathway associating PTSD with adverse outcomes after MI.

Hyperparathyroidism in celiac disease: always secondary?

It is well known that in celiac disease, malabsorption of calcium leads to secondary hyperparathyroidism as a response to hypocalcemia, and that secondary hyperparathyroidism is probably also due to concomitant vitamin D deficiency [1]. In patients with celiac disease, bone loss and derangement are extremely frequent, and there are recent data that show in celiac disease the release of proinflammatory cytokines activating osteoclasts may contribute to osteopenia and osteoporosis. Although the risk of fractures in celiac disease patients seems only slightly increased, it remains a clinical concern. Furthermore, osteomalacia in celiac patients is sometimes seen even if its exact prevalence remains unknown. A possible association between primary hyperparathyroidism and celiac disease has been reported recently [2, 3]. Here, we describe and discuss two cases of patients who simultaneously had both clinical conditions. Patient A: A 45-year-old woman hospitalized for severe osteomalacia, with inability to walk, history of nephrolithiasis, and iron-deficiency anemia unresponsive to oral iron therapy, was diagnosed with celiac disease which was confirmed by characteristic histologic changes on duodenal biopsy. At the time of her diagnosis, laboratory findings were as follows: hemoglobin 8.5 g/dL with mean corpuscular volume (MCV) 66 fl (83–97); serum calcium 2.38 mmol/L (2.1–2.55); phosphorus 0.53 mmol/L (0.87–1.45); parathyroid hormone (PTH) 478 pg/mL (11–64); 25-hydroxyvitamin D 3 ng/mL (9–38); ferritin 2 ng/mL (12–200); vitamin B12 168 pg/mL (211–911). The patient was started on a gluten-free diet, calcitriol 0.75 lg, calcium lactate-gluconate/calcium carbonate 2,000 mg daily and parenteral administration of iron and vitamin B12. With the start of the therapy, there was a marked improvement in the overall clinical picture with normalization of blood counts, and after 9 months, a return to the normal range of levels of antigliadin antibodies IgA—from 359.6 ng/mL to 5.5 ng/mL (0–5.9)—and antiendomysial antibodies IgA—positive from 1:2,560 to 1:5 (\1:5). However, despite correction of vitamin D deficiency (25-hydoxyvitamin D increased to 31 ng/mL), PTH levels remained high, 393 pg/mL, with evidence of hypercalcemia, 2.7 mmol/L and persistence of hypophosphatemia, 0.47 mmol/L. Her therapy was stopped (at that time calcitriol 0.25 lg, calcium lactate-gluconate/calcium carbonate 500 mg daily) and an ultrasound examination of the neck was performed with evidence of a hypoechoic oval structure, 1.8 cm in diameter, near the left lower pole of a normal thyroid gland, which suggested the possibility of an enlarged parathyroid gland. The patient underwent a technetium-99 m-labeled sestamibi scintigraphy that revealed a focus of activity consistent with a single left inferior parathyroid adenoma. The excision of the left parathyroid gland was carried out by an endocrine surgeon and then the histopathological examination showed a parathyroid adenoma. Thereafter, the patient experienced a progressive increase in bone mass density (with normal serum levels related to osteo-calcium metabolism), and she is now leading a normal life albeit with gluten-free diet. Patient B: A 42-year-old woman was examined for evaluation of a syndrome characterized by generalized weakness, anxiety and depression, and iron deficiency anemia unresponsive to oral iron therapy. By clinical S. C. Wu S. Caravita M. B. Secchi (&) Azienda Ospedaliera Istituti Clinici di Perfezionamento, U.O.C. Medicina Interna, Ospedale Bassini, via Massimo Gorki 50, 20092 Cinisello Balsamo, Milan, Italy e-mail: beatrice.secchi@fastwebnet.it

Évaluation de la réponse thérapeutique en cancérologie : place de l’imagerie isotopique

In comparison with conventional imaging, nuclear medicine offers an original metabolic approach for the assessment of the therapeutic response. Gallium 67, thallium 201, technetium 99m-labeled sestamibi and diphosphonates can be performed for therapeutic response assessment in lymphoma, brain and breast tumours, sarcoma, or bone metastasis. PET-CT facilities are now easily available in France and are ready to provide a new and accurate tool in oncology, specially for therapeutic evaluation. The procedure consists in the injection of fluor-18-fluoro-déoxyglucose (18FDG), an analogue of glucose, followed by a PET then a CT acquisition for FDG uptake abnormalities location. Therapeutic response is assessed by a decrease of 18FDG tumoral uptake between two consecutive studies. Methodology and interpretation criteria have been recently defined in international guidelines. 18FDG-PET-CT seems to be a valuable tool for therapeutic response assessment of patients with Hodgkin or non Hodgkin malignant lymphoma. Promising preliminary results have been recently published for lung, gastro-intestinal and head and neck cancers. PET-CT could also be able to predict the therapeutic response after the first courses of chemotherapy, allowing an early treatment optimization. Finally, new PET agents pave the way for molecular imaging with promising results in gene therapy and targeted treatment in oncology.

Section 1. Parathyroid: Prognosis of parathyroid function after minimally invasive radioguided parathyroidectomy (MIRP) and percutaneous ethanol injection therapy (PEIT) for primary hyperparathyroidism

During parathyroidectomy (PTx) for primary hyperparathyroidism (PHP), we surgically explored the contralateral parathyroid glands as well as those whose localization was clarified by ultrasonography and parathyroid scintigraphy. Although it is important to explore the contralateral side and other glands, we frequently treat only the gland whose localization is confirmed. Recently, we have performed minimally invasive radioguided parathyroidectomy (MIRP) that resects only one gland observed on the imaging under technetium 99m-labeled sestamibi (MIBI) scanning guidance after obtaining prior informed consent. In this surgery, even if recurrence is observed contralaterally, it is possible to apply a similar procedure to the contralateral side again. We examined six PHP patients who underwent MIRP and two PHP patients treated with percutaneous ethanol injection therapy (PEIT). The follow-up period was 2 years. PEIT was selected as a treatment method for two patients based on the patients’ characteristics. When only one gland is treated, the efficacy of PEIT was considered to be similar to that of MIRP.

Comparison of the accumulation and efflux kinetics of technetium-99m sestamibi and technetium-99m tetrofosmin in an MRP-expressing tumour cell line

The potential clinical use of technetium-99m labeled sestamibi (Tc-MIBI) and tetrofosmin (Tc-Tfos) to image tumours is currently being evaluated. In this study. the accumulation and efflux of Tc-MIBI and Tc-Tfos in the nasopharyngeal carcinoma cell line CNE-1 were examined in the presence or absence of various inhibitors of P-glycoprotein (PGP) and/or multidrug resistance associated protein (MRP) activity [GG918, PSC833, verapamil (Vrp), cyclosporin A (CsA) and buthionine sulfoximine (BSO)]. Reverse-transcriptase polymerase chain reaction analysis and immunodetection of the CNE-1 cells detected expression of MRP, MRPI and MRP2 but not PGP. Tc-MIBI and Tc-Tfos accumulation was increased (P < 0.0001) and efflux decreased (P < 0.05) in the presence of BSO, CsA, Vrp and PSC833 but not GG918, which is a specific inhibitor of PGP. The absolute accumulation of Tc-MIBI was approximately twofold higher than that seen with Tc-Tfos, whereas the addition of inhibitors caused a much greater suppression of Tc-Tfos transport (>2 times greater than for Tc-MIBI). However, no qualitative differences in inhibitors were seen between Tc-MIBI and Tc-Tfos. These results suggest that both Tc-MIBI and Tc-Tfos are substrates for the MRP transporter and that PSC833, Vrp, CsA and BSO but not GG918 can inhibit MRP activity. These results indicate that Tc-MIBI and Tc-Tfos may be suitable imaging agents for detecting MRP-mediated drug resistance in human cancers.

Direct comparison of technetium 99m—sestamibi and technetium 99m—tetrofosmin cardiac single photon emission computed tomography in patients with coronary artery disease

Background. Technetium 99m-labeled sestamibi and tetrofosmin tomography have shown high diagnostic accuracy in the detection of coronary artery disease (CAD) . However, few data are available comparing sestamibi and tetrofosmin imaging in the same patients. The aim of the study was to determine the image quality of the two tracers and to compare the results of exercise sestamibi and tetrofosmin tomography in the same patients. Methods. The results of exercise-rest sestamibi and tetrofosmin myocardial tomography were compared in 32 patients with suspected or known CAD who underwent coronary angiography. Image quality was evaluated subjectively. Regional tracer distribution was visually assessed and quantitatively measured in 22 segments/patient. Results. At coronary angiography, 7 patients had normal coronary vessels, 11 single-vessel, and 14 multivessel CAD (≥50 % luminal stenosis) . Image quality judged visually was comparable with the two tracers. Heart/lung and heart/liver ratios for sestamibi and tetrofosmin were not different. At visual analysis, 68 % of the patients with CAD had abnormal findings with sestamibi and 76% with tetrofosmin ( p = NS) . At quantitative analysis, 92% of the patients with CAD had abnormal findings with sestamibi and 96 % with tetrofosmin ( p = NS) . At both visual and quantitative analyses, sensitivity, specificity, and diagnostic accuracy in the detection of individual stenosed vessels were not different between the two tracers. Moreover, for both tracers sensitivity, specificity, and diagnostic accuracy in the detection of diseased vessels were significantly higher (all p < 0.05) at quantitative compared with visual analysis. Finally, defect size and severity were similar for the two tracers.p ] Conclusions. Exercise-rest sestamibi and tetrofosmin tomography yielded images of comparable quality and provided similar results in the identification of patients with CAD and in the detection of the individual stenosed coronary vessels.

Minimally invasive parathyroidectomy facilitated by intraoperative nuclear mapping

Background. The inability to predict the location and number of diseased parathyroid glands has precluded the wide acceptance of unilateral neck exploration for primary hyperparathyroidism. We used intraoperative nuclear mapping in patients identified by sestamibi scanning to have a single adenoma in hopes of minimizing operative intervention while maintaining the efficacy of a full exploration. Methods. Fifteen consecutive patients with primary hyperparathyroidism underwent technetium 99m-labeled sestamibi scanning 3.0 ± 0.1 hours before operation. Placement of the initial 2.0 cm incision and all dissection were guided by quantitative gamma counting in four neck quadrants with an 11 mm Neoprobe. Ex vivo radioactivity was determined for parathyroid glands, fat, and lymph nodes. Potential radiation hazards were assessed. Results. Intraoperative nuclear mapping discriminated between 14 solitary adenomas and one patient with four-gland hyperplasia that was not predicted on preoperative sestamibi scanning. Removal of the adenoma resulted in a decline in radioactivity in that quadrant (p < 0.001) and the entire neck (p < 0.05), with equalization of all neck quadrants. Ex vivo counts always identified parathyroid tissue (p < 0.0001 versus fat and lymph node). Adenomas were located in 19 ± 1.7 minutes through a 2.3 ± 0.1 cm incision. No significant radiation hazard existed, and no special handling of the specimen was required (0.06 ± 0.01 mR/hr). Conclusions. Intraoperative nuclear mapping complements sestamibi scanning to help distinguish single-gland from multigland disease. This technique allows for a minimally invasive operation under local anesthesia in a true outpatient setting.

Prediction of severe coronary artery disease by combined rest and exercise radionuclide angiocardiography and tomographic perfusion imaging with technetium 99m-labeled sestamibi: A comparison with clinical and electrocardiographic data

Background. The purpose of this study was to compare the incremental value of clinical information, electrocardiographic data, myocardial perfusion imaging, and radionuclide angiography for predicting severe coronary artery disease at a single testing interval. Clinical information, treadmill exercise studies, radionuclide angiography, and myocardial perfusion imaging are important predictors of severe coronary artery disease. However, the relative and absolute diagnostic importance of each of these methods has not been addressed at a single testing interval. Methods and Results. A same-day rest/treadmill exercise perfusion and function study was performed in 167 patients within 90 days of coronary angiography. A multivariable regression model was used to assess the independent informational content of these predictors. Clinical and electrocardiographic data were related strongly to the presence of severe coronary artery disease ( ξ 2 = 12.2 and p < 0.001; ξ 2 = 11.8 and p < 0.001, respectively). Combined perfusion and functional studies contributed 31% of the diagnostic information beyond that provided by clinical and electrocardiographic data alone ( p < 0.05). Conclusions. These data demonstrate that combined studies of myocardial perfusion and left ventricular function are able to improve prediction of the extent of coronary artery disease, even when clinical and electrocardiographic data are also available.

Residual area at risk after anterior myocardial infarction: Are ST segment changes during coronary angioplasty a reliable indicator? A comparison with technetium 99m-labeled sestamibi single-photon emission computed tomography

Background. The aim of this study was to assess whether, after anterior myocardial infarction, ST segment changes during percutaneous transluminal coronary angioplasty (PTCA) of the left anterior descending coronary artery correlated with the amount of ischemic myocardium in the area at risk, measured with 99mTc-labeled sestamibi single-photon emission computed tomography (SPECT) during balloon inflation. Methods and Results. Quantitative continuous monitoring of the ST segment was performed during PTCA of the left anterior descending coronary artery in 11 patients, and corresponding SPECT imaging was compared with a rest acquisition performed before PTCA. SPECT was quantified by a bull's-eye analysis according to main criteria: (1) the planimetered defect size during PTCA as an indicator of the size of the area at risk, (2) the change in the pathologic/normal area count ratio in the area at risk as an index of the severity of ischemia, and (3) the difference between the size of the defect during PTCA and at baseline. ST segment changes were correlated to the variation in pathologic/normal area count ratio (19% ± 14%; r = 0.61; p < 0.05) but not to the sizes of the scintigraphic defects. Conclusion. ST segment changes induced by occlusion of the infarct-related coronary artery during PTCA are related mostly to the severity of ischemia rather than to the size of the area at risk.

Combined analysis of resting regional wall thickening and stress perfusion with electrocardiographic-gated technetium 99m-labeled sestamibi single-photon emission computed tomography: Prediction of stress defect reversibility

Background. The high photon flux and stable distribution of the myocardial perfusion agent 99mTc-labeled sestamibi allow the perfusion data to be acquired in an electrocardiographic (ECG)-gated mode, such that information on resting regional wall thickening may be obtained simultaneously with stress perfusion data. The objective of this study was to assess whether visual analysis of resting regional wall thickening provided by ECG-gated acquisition of 99mTc-labeled sestamibi stress perfusion images correlates with and predicts the reversibility of stress-induced perfusion defects, potentially obviating the need for rest imaging. Methods and Results. Fifty-nine patients referred for myocardial perfusion imaging were studied with rest and stress single-photon emission computed tomographic (SPECT) sestamibi imaging, and the stress perfusion data were acquired in an ECG-gated mode. Visual analysis of the presence and reversibility of stress perfusion defects on standard imaging was correlated with the wall thickening data from the poststress gated SPECT images. Quantitative circumferential profile analysis of the short-axis images was performed to assess the influence of relative stress perfusion defect severity on the correlation between wall thickening and defect reversibility. Among the 72 segments with stress-induced perfusion defects and visually apparent wall thickening on ECG-gated SPECT images, 69 were reversible on rest imaging (positive predictive value of 96% for wall thickening to predict stress defect reversibility). Of the 35 segments with stress-induced defects and no apparent wall thickening on ECG-gated SPECT images, however, 14 (40%) demonstrated significant stress defect reversibility on rest imaging. This result represents a negative predictive value of only 60% for the lack of apparent wall thickening to predict correctly an irreversible stress defect. Among the segments with reversible stress perfusion defects and visually apparent wall thickening, relative stress sestamibi activity was higher (51% ± 10% [percentage of peak]) than in segments with reversible stress defects and no visually apparent wall thickening (39% ± 4% of peak activity [ p < 0.0001]). Conclusions. Visual evidence of wall thickening by poststress ECG-gated SPECT sestamibi imaging in the territory of a stress-induced perfusion defect correlates highly with stress defect reversibility on rest imaging and may obviate the need to perform rest imaging, thereby potentially reducing the time and cost involved in myocardial perfusion imaging. The absence of visually apparent wall thickening, however, underestimates the prevalence of stress defect reversibility on rest imaging; in such instances, rest imaging must be performed to differentiate ischemia from infarction in the territory of a stress perfusion defect.

Estimation of attenuation maps from scatter and photopeak window single photon-emission computed tomographic images of technetium 99m-labeled sestamibi

Background. In single photon-emission computed tomographic imaging of the chest, nonuniform attenuation correction requires use of a patient-specific attenuation map. The aim of this study was to determine whether an estimate of the regions of the lungs and nonpulmonary tissues of the chest could be obtained by segmenting the photopeak and Compton scatter window images in a phantom and in patients to estimate patient-specific attenuation maps. Methods and Results. The photopeak and scatter window slices from 16 consecutive 99mTc-labeled sestamibi perfusion studies were segmented interactively. In these studies, visually reasonable regions could be obtained by estimating a “cold” lung region from scatter window data with additional anatomic information of the myocardium region, the backbone and sternum locations, the liver, and the rib cage from the photopeak window data. In an anthropomorphic torso phantom study and a patient study, comparison was made between the attenuation maps based on segmentation of the emission images and transmission imaging with a slant-hole collimator. It was determined that good agreement in the estimation of the body regions can be achieved with segmentation of the emission images in both the phantom and patient data. Attenuation correction using the maximum-likelihood expectation maximization method was performed on the phantom and the patient data. In both studies, attenuation correction with the segmented attenuation map improved uniformity of the inferior wall region in comparison with the other walls. Conclusions. The estimation of patient-specific attenuation maps by segmenting the scatter and photopeak window slices of 99mTc-labeled sestamibi studies may be a way of reducing the loss of specificity due to attenuation artifacts. The potential limitations on the accuracy of correction inherent in the method due to the estimation of the regions and assignment of the attenuation coefficients need to be determined further, and the method needs to be further automated before it can be considered for routine clinical use.

Diagnostic accuracy of dipyridamole technetium 99m-labeled sestamibi myocardial tomography for detection of coronary artery disease

Background. The diagnostic accuracy of exercise 99mTc-labeled sestamibi and intravenous dipyridamole 201T1-labeled myocardial tomography is established. The accuracy of dipyridamole stress 99mTc-labeled sestamibi myocardial tomography for the detection of coronary artery disease has not been reported. Methods and Results. Our purpose was to determine the diagnostic accuracy of same-day, rest-dipyridamole stress 99mTc-labeled sestamibi myocardial single-photon emission computed tomography (SPECT) compared with coronary angiography. Two hundred forty-four patients who were unable to exercise adequately underwent both dipyridamole 99mTc-labeled sestamibi SPECT and coronary angiography within 6 months. Dipyridamole was administered intravenously in a standard dose of 0.56 mg/kg for 4 minutes. Cardiac and noncardiac side effects were recorded. The presence of coronary stenoses of 50% or greater diameter reduction in each of the major coronary arteries was compared with imaging data in corresponding myocardial perfusion beds. The patient population was predominately (98.8%) male with a mean age of 63 ± 9 years (range 33 to 83 years). The majority of patients had stable angina (88%). Eighty-four patients (35%) gave a prior history of myocardial infarction; 44 patients (18%) had a history of congestire heart failure. The principal limitation to exercise stress was peripheral vascular disease in 62 patients (26%). No serious side effects occurred during dipyridamole stress; 14% of patients had chest pain and 8% of patients had 1 mm or greater ST segment depression. Of the 204 patients with documented coronary stenoses, 43 (21%) had single-vessel disease and 161 (79%) had multivessel disease. The sensitivity was 93% ( 40 43 in patients with single-vessel disease) and 91% ( 146 161 in patients with multivessel disease). Overall sensitivity was 91%. The specificity was 28% ( 11 40 ) in this population with a high prestest probability of coronary artery disease and posttest referral for cardiac catheterization. Conclusion. 99mTc-labeled sestamibi myocardial tomography in conjunction with intravenous dipyridamole stress is a safe and sensitive method for the detection of coronary artery disease. The diagnostic accuracy of dipyridamole stress 99mTc-labeled sestamibi SPECT for the detection of coronary artery disease is similar to that reported for exercise stress 99mTc-labeled sestamibi tomography, making this a suitable alternative for the evaluation of patients who are unable to exercise adequately.

Preoperative parathyroid localization with sestamibi

Results of noninvasive preoperative parathyroid localization with technetium99m-labeled sestamibi are reported in a series of 51 patients. Forty-four patients had hyperparathyroidism surgically treated for the first time and seven patients underwent reexploration for recurrent or persistent hyperparathyroidism. Preoperative scintigraphy with sestamibi was performed in all patients before surgical exploration. Results of the radionuclide studies were compared with surgical and pathologic findings. Twenty-six patients had solitary adenomas. All 26 were localized preoperatively by the scans. Among 18 patients with multiglandular pathology, 69 pathological glands were found at surgery. Thirty-six of these glands, in 15 patients, were localized by the scans. Among the 7 patients evaluated after failed exploration or recurrent hyperparathyroidism, 7 pathologic glands were found, of which 6 were correctly localized by the scan. Ectopic lesions in 2 patients were correctly localized by the scan. The authors conclude that sestamibi parathyroid localization is an effective method for preoperative parathyroid localization, with accuracy exceeding that of other noninvasive studies.

Quantitative comparison of single-isotope and dual-isotope stress-rest single-photon emission computed tomographic imaging for reversibility of defects

Background. Dual-isotope rest/stress single-photon emission computed tomographic (SPECT) imaging is a time-saving imaging protocol. However, the stress radiotracer, technetium 99m-labeled sestamibi, and the rest radiotracer, thallium 201, have different physical properties and myocardial kinetics. In patients with abnormal resting myocardial perfusion, these differences may affect quantification of rest defect size and defect reversibility. The purpose of the study was to compare myocardial perfusion defect reversibility quantitatively by single-isotope (rest/stress sestamibi) and dual-isotope (rest thallium/stress sestamibi) SPECT. Methods and Results. Thirty patients with prior myocardial infarction underwent rest/stress sestamibi SPECT imaging and rest thallium SPECT imaging. Defects were quantified according to circumferential count profiles with a normal sestamibi database. The images of a subgroup of 21 patients were processed with radiotracer-specific normal databases. Defect size and defect reversibility were compared quantitatively for single-isotope and dual-isotope SPECT. Rest sestamibi defect size was significantly larger than rest thallium defect size (19 ± 15 vs 14 ± 16; p = 0.007). Defect reversibility was larger with thallium than with sestamibi (10 ± 9 vs 6 ± 6; p = 0.002). With radiotracer-specific normal databases, mean rest sestamibi and thallium defect sizes in 21 patients were not different (23 ± 19 vs 21 ± 17; difference not significant). With radiotracer-specific normal databases, mean defect reversibility was not different with either sestamibi or thallium (6 ± 6 vs 8 ± 9; difference not significant), although correlation among individual patients was only fair ( r 2 = 0.48). Conclusion: In patients with prior myocardial infarction, stress-induced defect reversibility is quantitatively larger with dual-isotope imaging than with single-isotope imaging. Quantitative processing of dual-isotope images requires radiotracer-specific normal databases. Because of different characteristics of sestamibi and thallium, assessment of defect reversibility on dual-isotope images should be made with caution. Only relatively large defect reversibility can be assumed to represent true stress-induced myocardial ischemia.

Detection of coronary artery disease: Comparison between technetium 99m-labeled sestamibi single-photon emission computed tomography and two-dimensional echocardiography with dipyridamole low-level exercise-stress

Background. Myocardial perfusion imaging in conjunction with dipyridamole low-level exercise stress has proved its value in the evaluation of patients with coronary artery disease (CAD). Simultaneous wall motion analysis by two-dimensional (2D) echocardiography may provide additional information beyond that obtained by myocardial perfusion imaging alone. The purpose of this study was to compare 99mTc-labeled sestamibi single-photon emission computed tomography (SPECT) and 2D echocardiography for the evaluation of CAD according to a dipyridamole low-level bicycle exercise stress protocol. Methods and Results. We studied 35 consecutive patients referred for the evaluation of chest pain who had undergone coronary arteriography. 99mTc-labeled sestamibi SPECT and 2D echocardiography agreed in 27 patients (80%) studied for overall detection of CAD. On a segmental basis, agreement was found between SPECT and 2D echocardiography in 124 (73%) of 170 segments (Cohen's kappa = 0.43). The accuracy of the combined assessment of myocardial perfusion and echocardiographic wall motion in detecting CAD was 86%, which was not different from the accuracy of SPECT alone (80%; difference not significant) but significantly higher than for 2D echocardiography alone (71%; p = 0.03). In the detection of individual coronary artery stenoses, SPECT had a significantly higher accuracy for detecting left anterior descending coronary artery lesions than had 2D echocardiography (80% vs 60%; p < 0.01); combining the two methods did not improve the accuracy (80%). The combined assessment slightly improved the accuracy for detecting left circumflex coronary artery stenoses from 71% to 83% ( p = 0.05). Conclusion. The combined simultaneous assessment of myocardial perfusion by 99mTc-labeled sestamibi SPECT and wall motion by 2D echocardiography did not significantly improve overall accuracy over that obtained by 99mTc-labeled sestamibi SPECT alone. Therefore 99mTc-labeled sestamibi SPECT with dipyridamole low-level exercise stress appears the preferred imaging modality for the evaluation of patients with CAD.

Ninety-day follow-up of patients in the emergency department with chest pain who undergo initial single-photon emission computed tomographic perfusion scintigraphy with technetium 99m-labeled sestamibi

Background. Patients in the emergency department with typical chest pain and a normal or nondiagnostic electrocardiogram have a 10% to 20% risk of nonfatal myocardial infarction. These patients can be stratified into groups of very low and very high risk for inpatient adverse cardiac events on the basis of initial 99mTc-labeled sestamibi single-photon emission computed tomographic (SPECT) perfusion imaging performed during symptoms. However, the intermediate or posthospital discharge prognosis of such patients has not been reported. Methods and Results. Patients ( n = 150) with typical chest pain (based on a semiquantitative chest pain questionnaire) and a normal or nondiagnostic electrocardiogram underwent injection of 15 to 45 mCi 99mTc-labeled sestamibi injected during symptoms. Ninety-day follow-up history (telephone questionnaire and review of medical records) was obtained in 140 patients, and follow-up electrocardiography was performed in 72 patients. Cardiac events (death, nonfatal myocardial infarction, thrombolysis, percutaneous transluminal coronary angioplasty, or coronary artery bypass grafting) occurred before hospital discharge in 33 patients (18%), and these patients were excluded from further analysis. At follow-up, two (8%) of 25 patients with an abnormal initial scintigram and none of 87 patients with a normal scan had cardiac events ( p = 0.008). Conclusions. In patients with typical angina and a normal or nondiagnostic electrocardiogram, initial SPECT scintigraphy allows early accurate risk stratification. The previously observed excellent inpatient prognosis of patients with a normal scintigram appears to extend for at least 90 days of follow-up. These observations may provide a rational basis for safe and cost-effective outpatient evaluation of selected patients in the emergency department with typical angina, a normal or nondiagnostic electrocardiogram, and a normal initial 99mTc-labeled SPECT perfusion scintigram performed during symptoms.

Quantification of technetium 99m-labeled sestamibi single-photon emission computed tomography based on mean counts improves accuracy for assessment of relative regional myocardial blood flow: Experimental validation in a canine model

Background. Quantification of single-photon emission computed tomographic (SPECT) images is generally based on determination of maximal counts on radial sectors of short-axis slices. We hypothesized that analysis of mean counts may reduce estimation error. Methods and Results. We compared quantitative 99mTc-labeled sestamibi (MIBI) SPECT based on maximal myocardial counts with that based on mean myocardial counts for accuracy of quantifying relative regional myocardial perfusion in a canine model of permanent left anterior descending coronary artery occlusion. MIBI and radiolabeled microspheres were injected during left anterior descending coronary artery occlusion. Relative microsphere myocardial blood flow was expressed as a percentage of normal (left circumflex coronary artery territory) blood flow. SPECT imaging was performed in vivo and ex vivo. Relative MIBI uptake on SPECT short-axis slices was quantified with normalized circumferential profiles based on maximal and mean counts. In vivo and ex vivo SPECT relative myocardial count density was compared to relative myocardial blood flow in six dogs. In the comparisons, percent errors in estimating the relative blood flow and relative flow deficit with MIBI SPECT imaging were calculated. There was an excellent correlation between absolute myocardial tissue MIBI activity and regional myocardial blood flow for each of the six dogs ( r = 0.90 to 0.98). The correlations between relative myocardial count density on SPECT and relative blood flow for individual sectors were similar for maximal and mean count profiles (maximal, 0.79 to 0.83; mean, 0.77 to 0.82). Comparing the nadirs of in vivo and ex vivo circumferential count profiles, the correlations were slightly better (maximal, 0.82 to 0.91; mean, 0.87 to 0.91). Average percent errors in assessing relative blood flow and relative flow deficit were decreased significantly by use of mean count profiles ( p < 0.05). Conclusions. Relative SPECT count density with either maximal or mean count profiles correlated well with relative myocardial blood flow. Compared with maximal count profiles, quantification with mean count profiles improved estimation of relative flow.

Incremental diagnostic value of dobutamine stress echocardiography and dobutamine scintigraphy (technetium 99m-labeled sestamibi single-photon emission computed tomography) for assessment of presence and extent of coronary artery disease

Background. The incremental diagnostic value of dobutamine stress echocardiography (DSE) and 99mTc-labeled sestamibi single-photon emission computed tomography for the evaluation of the presence and extent of coronary artery disease (CAD) was assessed with ordered logistic regression and receiver-operating characteristic curves. Methods and Results. Forty-five consecutive patients (33 men and 12 women; 53 ± 6.8 years) underwent exercise electrocardiography and simultaneous DSE and sestamibi single-photon emission computed tomographic imaging. Coronary angiography was performed in all patients (significant coronary stenosis >50%). On the basis of the results of exercise electrocardiography, the pretest probability for CAD (Diamond's algorithm) was low (45.6% ± 12.7%). According to ordered logistic regression analysis, some models were estimated that performed a diagnostic accuracy level for CAD. In particular, we evaluated a clinical model (model 1) determined by the following parameters: sex, age, presence of chest pain, and positivity of electrocardiogram during dobutamine stress test. This model was 64.3% ± 10.7% accurate for the prediction of CAD. The addition to model 1 of DSE parameters (wall motion stress and rest score index and relative difference) (model 2) yielded a diagnostic accuracy of 81.4% ± 4.3% ( p < 0.045), whereas the addition to model 1 of single-photon emission computed tomographic parameters (the difference between perfusional stress and rest score index) (model 3) improved diagnostic accuracy to 92.3% ± 5.5% ( p < 0.003), a level that appeared significantly higher than that of model 2 ( p < 0.016). Conclusion. Both noninvasive methods for the detection of CAD showed a good diagnostic accuracy, especially when test-derived parameters were combined with clinical data. Nevertheless, the single-photon emission computed tomographic model showed a higher sensitivity compared with the DSE model.

Influence of the assessment of defect severity and intravenous nitrate administration during tracer injection on the detection of viable hibernating myocardium with data-based quantitative technetium 99m-labeled sestamibi single-photon emission computed tomography

Background. This study aimed to verify whether the assessment of defect severity and the infusion of nitrates during tracer injection improve the capability of data-based 99mTc-labeled sestamibi single-photon emission computed tomography (SPECT) to recognize hibernating myocardium. Methods and Results. Of 66 asynergic coronary territories in 40 patients with left ventricular dysfunction, 28 had postrevascularization functional recovery (hibernating) and 38 had unchanged dysfunction (fibrotic). Defect severity was lower in the hibernating than in the fibrotic territories on both baseline ( p < 0.01) and nitrate SPECT ( p < 0.002). Nitrate was superior to baseline SPECT to differentiate the hibernating from the fibrotic territories (sensitivity 96% vs 75%, p < 0.05; receiver-operating characteristic curve area 0.75 vs 0.63, p < 0.001) and to identify the patients with improved left ventricular ejection fraction (receiver-operating characteristic curve area 0.68 vs 0.58; p < 0.05). Conclusions. The analysis of defect severity in combination with nitrate infusion clearly improves the value of 99mTc-labeled sestamibi SPECT for the recognition of hibernating myocardium and the prediction of postrevascularization recovery.

Fast technetium 99m-labeled sestamibi gated single-photon emission computed tomography for evaluation of myocardial function

Background. This study assesses the feasibility of 99mTc-labeled sestamibi electrocardiographic gated single-photon emission computed tomography (SPECT) with a short acquisition time (6.7 minutes, “fast” gated SPECT) for the evaluation of stress myocardial perfusion and poststress myocardial function. Simultaneous assessment of stress perfusion and poststress function is possible with standard gated SPECT acquisition (19.3 minutes) of stress-injected sestamibi. Sestamibi gated SPECT can be used to evaluate regional wall motion (RWM), thickening, and left ventricular ejection fraction (LVEF); the feasibility of fast gated SPECT has not been evaluated previously. Methods and Results. Fifty patients were studied who underwent treadmill exercise, sestamibi injection (25 to 30 mCi), and standard gated SPECT 15 minutes after exercise, immediately followed by fast gated SPECT. All patients underwent rest 201 Tl SPECT before exercise testing. All studies were analyzed by semiquantitative visual scoring. Both standard and fast gated SPECT were read for stress perfusion and poststress wall motion and thickening, dividing the left ventricle into 20 segments, on a 5-point scale described previously. The measurement of LVEF used a previously described automatic algorithm. Average myocardial counts per pixel were 58 ± 19 for standard gated SPECT and 13 ± 4 for fast gated SPECT ( p = 0.0001). Heart/lung ratio was 10.2 ± 4.8 for regular gated SPECT and 10.3 ± 5.7 for fast gated SPECT (difference not significant). Perfusion analysis showed exact agreement in 92% of the segments (κ = 0.76; p <0.01). Correlation between LVEFs measured from standard and fast gated SPECT was 0.94. Analysis of 998 segments (two segments were uninterpretable) showed exact agreement in 96% (κ = 0.89; p < 0.001) for RWM and 94% (κ = 0.83; p < 0.001) for thickening between standard and fast gated SPECT. In 225 segments with abnormal RWM and 189 segments with abnormal thickening by both standard and fast gated SPECT, exact agreements were 0.92 for RWM (κ = 0.90; p < 0.001) and 0.87 for thickening (κ = 0.80; p < 0.01). Conclusions. Our data demonstrate that fast sestamibi gated SPECT is feasible and yields results equivalent to those of standard sestamibi gated SPECT with respect to left ventricular regional and global function.