Sestamibi Imaging Research Articles

The false positive sestamibi scan: Influence of thyroid disease

Objectives: Develop a protocol for the localization of parathyroid adenoma and characterization of nodular thyroid lesions in order to optimize the application of a minimally invasive approach to hyperparathyroidism. Methods: A retrospective evaluation of 466 patients with primary hyperparathyroidism in whom directed exploration was performed by a single surgeon at an academic tertiary care medical center. The study population consisted of patients for whom surgical findings indicated a false-positive preoperative technetium 99m sestamibi scan. Results: The accuracy of sestamibi imaging in predicting the location of parathyroid adenoma was 92%. Thirty-two patients were found to have surgical findings inconsistent with the location predicted by the scan (false-positive scans). The presence of concurrent thyroid abnormalities was noted in all 32 patients, the location of the abnormality coinciding with the area of delayed uptake noted on the scan. In total, 60 patients demonstrated obvious thyroid abnormalities at exploration. All thyroid lesions demonstrating retained radiotracer were solid whereas the remaining 28 nodules were cystic and did not concentrate sestamibi. Twenty-three of the 32 patients with false-positive imaging demonstrated clinically palpable thyroid nodules preoperatively. Conclusions: In the presence of a known or clinically demonstrated thyroid abnormality in patients with hyperparathyroidism and focal uptake of sestamibi, a high resolution ultrasound of the thyroid gland will be of benefit in assessing the risk for a false positive localization scan, ie, cystic vs solid nodule. This will determine the applicability of a directed minimally invasive approach.

Differential prognostic significance of peri-infarction versus remote myocardial ischemia on stress technetium-99m sestamibi tomography in patients with healed myocardial infarction

Peri-infarction and remote myocardial ischemia involve different myocardial substrates, but their differential clinical implications have not been previously studied. We assessed the differential prognostic significance of peri-infarction and remote ischemia during long-term follow-up in patients with healed myocardial infarction. We studied 345 patients (59 ± 12 years old; 282 men) with previous myocardial infarction who demonstrated reversible perfusion abnormalities on exercise or dobutamine stress technetium-99m sestamibi tomography. Follow-up events for 5.5 ± 2.6 years were 60 deaths (17%; 40 cardiac deaths) and 25 reinfarctions (7%). Reversible perfusion abnormalities were detected in the remote region in 129 patients (37%), the peri-infarction region in 142 patients (41%), and in both regions in 74 patients (21%). The annual rates of cardiac death in these groups were 1.2%, 2.8%, and 2.9%, respectively (p <0.01). The annual rates of reinfarction were 1%, 1.5%, and 0.9%, respectively (p = NS). In a multivariate analysis model, independent predictors of cardiac death were history of heart failure (risk ratio [RR] 2.8, 95% confidence interval [95% CI] 1.2 to 7), diabetes mellitus (RR 4.1, 95% CI 1.9 to 8.9), summed score at rest (RR 1.4, 95% CI 1.1 to 3.1), and peri-infarction ischemia (RR 2.6, 95% CI 1.1 to 6.1). Predictors of reinfarction were age (RR 1.03, 95% CI 1.01 to 1.07) and diabetes mellitus (RR 3.3, 95% CI 1.2 to 9.1). Peri-infarction ischemia assessed by stress technetium-99m sestamibi tomography is associated with a greater risk of cardiac death than is remote ischemia. The risk of reinfarction is not related to the location of ischemia.

Upright vs. supine imaging–a clinical comparison

Background: Recently small, portable, upright cameras for myocardial perfusion SPECT (mps) have been increasingly utilized in the outpatient setting. To date, there have been no direct comparisons of this imaging technique to the more standard supine approach. We therefore sought to compare these two techniques. Methods: 59 consecutive outpatients referred for MPS were imaged in the standard supine position (on a Phillips Vertex Plus™) as well as in the upright position (on a DIGIRAD Cardiu™-2). Both rest and stress images were acquired on both cameras and the order of acquisition, for both rest and stress, was chosen randomly. All patients were imaged using a low-dose rest/high-dose stress Tc99m sestamibi protocol and imaging time on both systems was the same (35 seconds/stop × 64 stops for rest and 25 seconds/stop × 64 stops). Processing was performed using iterative reconstruction and no attenuation correction was used. The gold-standard (GS) was the clinical imaging protocol, which included both supine and prone imaging at stress, as well as review of raw and clinical data at the time of interpretation. The images were then read blindly, in random order, and the clinical results were compared for the two systems. Raw data was not reviewed during the blind read as this would allow the reader to identify the camera used (based on the differing size of the field of view). Results: The patients were 68.8±10.5 years old and 66% male. 39 % underwent exercise stress and 61% underwent pharmacologic stress using adenosine (of these 66% underwent concomitant low-level treadmill exercise during the adenosine infusion). In 50/59 (85%) cases there was no difference in the clinical impression between the two systems. In the remaining cases 5/59 (9%) were deemed to be false positive (compared to GS) on upright imaging and 4/59 (7%) were deemed to be false positive (compared to GS) on supine imaging. Conclusion: Upright MPS imaging offers clinically similar results to the standard method.

Assessment of Response to Neoadjuvant Chemotherapy in Breast Cancer: Imaging Considerations

This article reviews current imaging techniques for assessing response to neoadjuvant chemotherapy in women with breast cancer. The rationale for the use of neoadjuvant chemotherapy is presented along with the need to accurately monitor response to therapy. Clinical examination, mammography, sonography, magnetic resonance imaging (MRI), sestamibi imaging, and positron emission tomography (PET) are assessed as techniques for monitoring response to preoperative chemotherapy. Also, placement of metal markers into the tumor bed in patients who demonstrate a favorable response to neoadjuvant chemotherapy is discussed.

Clinical value of attenuation correction in stress-only Tc-99m sestamibi SPECT imaging

Background Attenuation artifact remains a substantial limitation to confident interpretation of images and reduces laboratory efficiency by requiring comparison of stress and rest image sets. Attenuation-corrected stress-only imaging has the potential to ameliorate these limitations. Methods and results Ten experienced nuclear cardiologists independently interpreted 90 stress-only electrocardiography (ECG)–gated technetium 99m sestamibi images in a sequential fashion: myocardial perfusion imaging (MPI) alone, MPI plus ECG-gated data, and attenuation-corrected MPI with ECG-gated data. Images were interpreted for diagnostic certainty (normal, probably normal, equivocal, probably abnormal, abnormal, and perceived need for rest imaging). With stress MPI data alone, only 37% of studies were interpreted as definitely normal or abnormal, with a very high perceived need for rest imaging (77%). The addition of gated data did not alter the interpretations. However, attenuation-corrected data significantly increased the number of studies characterized as definitely normal or abnormal (84%, P < .005) and significantly reduced the perceived need for rest imaging (43%, P < .005). These results were confirmed by use of a nonsequential consensus interpretation of three readers. Conclusion Attenuation correction applied to studies with stress-only Tc-99m ECG-gated single photon emission computed tomography images significantly increases the ability to interpret studies as definitely normal or abnormal and reduces the need for rest imaging. These findings may improve laboratory efficiency and diagnostic accuracy.

Best for breasts: 99mTc sestamibi or 99mTc oxidronate?

Aim: The aim of this study was to compare 99mTc sestamibi and 99mTc oxidronate in patients with either equivocal or indeterminate triple assessment or for evaluation of co-existent disease in known breast cancer appearing suitable for management by wide local excision. Method: One hundred patients (199 breasts) underwent scintimammography with both 99mTc sestamibi and 99mTc oxidronate, with a maximum of 6 days between studies. Four experienced, ‘blinded’ observers scored each digital image on a scale of 1 (normal) through 3 (equivocal) to 5 (definitely malignant). Images were also ‘consensus’ reported by two observers aware of each patient's clinical history. Results: Sensitivity, specificity and ROC curves were calculated for each observer. ROC curves for each of the ‘blinded’ observers were significantly different from the ‘consensus’ observers for both 99mTc oxidronate (P=0.001) and 99mTc sestamibi (P=0.02). However, only borderline significant difference (P=0.04) exists between the ‘consensus’ ROC curves when scoring 99mTc sestamibi (sensitivity 87%, specificity 90%) or 99mTc oxidronate (sensitivity 90%, specificity 90%) images. Conclusions: Scintimammography, using either 99mTc sestamibi or 99mTc oxidronate, has high sensitivity, specificity and accuracy in the diagnosis of primary breast cancer. Although 99mTc sestamibi scintimammography is significantly better than 99mTc oxidronate scintimammography for ‘blind’ reporting, there is little difference in a ‘consensus’ clinical reporting context.

A Patient with Classic Severe Primary Hyperparathyroidism in Whom both Tc-99m MIBI Scintigraphy and FDG-PET Failed to Detect the Parathyroid Tumor

A 24-year-old woman was admitted to our department for further examination of hypercalcemia, a high level of intact parathyroid hormone (PTH) and a right parathyroid tumor. She complained of bone pain throughout her body and was unable to walk due to systemic cystic osteofibrosis, including a brown tumor of the left lower extremities. Neck ultrasonography (US) and magnetic resonance imaging (MRI) revealed a tumor 2 cm in diameter in the upper side of the right thyroid lobe. 99mTc sestamibi (99mTc-MIBI) imaging and F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) were performed to diagnose primary hyperparathyroidism and examination of other parathyroid glands. However, neither imaging modality detected the parathyroid tumor. To confirm the diagnosis, we performed selective venous sampling around the parathyroid and the patient was diagnosed with primary hyperparathyroidism due to a right parathyroid tumor. Resection of the right parathyroid tumor was performed and the pathological diagnosis was parathyroid adenoma. To date, both 99mTc-MIBI and FDG-PET are useful to localize parathyroid tumors. In this case, however, neither modality detected the tumor. Although recent studies state that expression of P-glycoprotein (P-gp) in parathyroid tumors plays an important role in the false-negative results of both 99mTc-MIBI scans and FDG-PET, immunohistological study detected no P-gp expression in the parathyroid tumor in the current case.

Double adenomas revisited: Nonuniform distribution favors enlarged superior parathyroids (fourth pouch disease)

Background A double adenoma (DA) is a recognized clinical entity of primary hyperparathyroidism (HPT) and is presumed to have uniform location distribution. We reviewed our experience with 2-gland parathyroid disease to identify anatomic patterns and implications for surgical management. Methods Clinical characteristics were reviewed for 828 consecutive patients with HPT at 2 endocrine referral centers that practice bilateral neck exploration with intraoperative parathyroid hormone (IOPTH) measurement. Results Fifteen percent (127 of 828) of HPT patients demonstrated 2 enlarged glands; 13% (107 of 828), 3- or 4-gland hyperplasia; and 71% (592 of 828), single adenomas. DAs in superior parathyroids affected 57 of 127 (45%) patients, an observed frequency 3-fold higher than expected ( P<.001, chi-square test). DAs were larger than normal glands (240±575 mg vs 28±23 mg, P<.001), and superior parathyroid adenomas were larger than adenomas at other sites (421±983 mg vs 202±353 mg, P = .002). Technetium 99 metastable (Tc99m)-sestamibi imaging and IOPTH identified DAs correctly in only 5 of 84 (6%) and 19 of 75 (25%) of patients tested, respectively. Conclusions DAs have nonuniform anatomic distribution with predilection for abnormal growth in bilateral superior parathyroids—embryologic remnants of the fourth branchial pouch. Since additional abnormal glands were detected by observation with technetium 99 metastable (Tc99m)-sestamibi imaging and IOPTH rarely aiding detection, unilateral neck exploration may predispose to persistent or recurrent HPT.

Directed parathyroid exploration: Evolution and evaluation of this approach in a single‐institution review of 346 patients

Critical evaluation of a directed exploration protocol used by a single surgeon in the management of surgical parathyroid disease. Retrospective chart review was made of patients surgically managed for hyperparathyroidism at an academic tertiary care center. Three hundred forty-six patients were evaluated for biochemically proven hyperparathyroidism between March 1995 and February 2002. A directed exploration protocol was implemented in appropriately selected patients with primary hyperparathyroidism and in patients with secondary or tertiary hyperparathyroidism requiring repeat operation. The protocol included preoperative technetium-99m sestamibi imaging for hyperfunctional parathyroid localization, targeted neck exploration, rapid intraoperative parathyroid hormone determination, and limited-stay discharge from the ambulatory surgical recovery unit. Data collection was accomplished by entering patient evaluation, management, and outcome information prospectively into collective case report forms. A retrospective analysis of the data was conducted for the purpose of evaluating the effectiveness of the protocol. Sustained normocalcemia beyond 6 months postoperatively was achieved in 323 of 327 (99%) patients with primary hyperparathyroidism. Eighty-four percent (84%) of patients with secondary or tertiary hyperparathyroidism achieved normocalcemia or had resolution of symptoms as a measure of therapeutic success. The complication rate for the entire series of patients was 2.8%. Ninety-two percent of positive findings on sestamibi scan correctly predicted the location of an adenoma, whereas a negative finding accurately predicted the absence of an enlarged gland in a "usual" location in 81% of patients. Twenty-six patients (9%) had a false-positive finding on the scan, whereby a solitary adenoma was found contralateral to the side indicated by the scan. Overall, the positive predictive value for sestamibi imaging in the series was 91%. Intraoperative parathyroid hormone determination yielded an overall rate of reduction of 80% from preoperative levels during directed exploration. Sustained normocalcemia was achieved in all patients in whom intraoperative parathyroid hormone determination demonstrated a minimum decline of 50% from preoperative levels following resection of hyperfunctional parathyroid tissue (adenoma[s]). The majority (72%) of patients were managed in an outpatient (ambulatory surgery) setting and were discharged to home within 8 to 12 hours after surgery. The directed exploration protocol for surgical management of hyperparathyroidism generated surgical rates of success that were as good as and, in most cases, improved over that of traditional bilateral exploration. This achievement was associated with low morbidity and reduced time and facility utilization, conveying improved cost-effectiveness. This surgical strategy should serve to enhance the capability of the surgeon to safely and efficiently manage the majority of patients with surgical parathyroid disease.

Selective intracoronary injection of sestamibi to detect myocardial viability: prediction of perfusion and contractile recovery after percutaneous transluminal coronary angioplasty

Background The main limitation of myocardial single photon emission computed tomography (SPECT) in detecting hibernating myocardium is the poor delivery of radiotracers in hypoperfused areas supplied by severely stenotic coronary arteries. Increasing local availability of radiotracers by intracoronary injection might represent an attractive solution. The hypothesis that the intracoronary administration of sestamibi could improve myocardial SPECT accuracy in detecting hibernating myocardium was addressed in this pilot study. Methods and results Seven patients with prior myocardial infarction and severe stenosis of the infarct-related artery underwent myocardial SPECT after intracoronary injection of technetium 99m sestamibi immediately before percutaneous transluminal coronary angioplasty (PTCA). Wall motion and perfusion were evaluated, before and 1 month after PTCA, by 2-dimensional echocardiography and rest-redistribution thallium 201 SPECT. A “low-flow area” was identified on the pre-PTCA Tl-201 SPECT image as the area with less than 50% of maximum radiotracer uptake. Changes in wall motion and perfusion in the low-flow area were compared with results of intracoronary sestamibi imaging. On a pixel-by-pixel analysis, intracoronary sestamibi predicted perfusion recovery within the low-flow area with a 91% sensitivity, a 78% specificity, and an 82% overall accuracy. Only in the 5 patients with an extent of sestamibi uptake greater than one third of the low-flow area was an improved regional and global left ventricular wall motion observed after PTCA (wall motion score index decreased from 1.95 ± 0.28 to 1.60 ± 0.34, P = .007; left ventricular ejection fraction increased from 42% ± 7% to 49% ± 7%, P = .001; asynergic segments in the low-flow area decreased from 3.6 ± 0.9 to 1.8 ± 1.5, P = .021). Conclusions In patients with prior myocardial infarction and severe stenosis of the infarct-related artery, sestamibi uptake after intracoronary administration identified viable myocardium that was undetected after rest-redistribution thallium SPECT but capable of clinically significant contractile improvement after revascularization.

Accuracy of detection of myocardial viability and residual infarct vessel stenoses with rest Tl-201 and adenosine Tc-99m sestamibi imaging after coronary reperfusion in dogs with experimental acute myocardial infarction

Background We sought to determine whether a dual-isotope imaging strategy (rest thallium 201/stress technetium 99m sestamibi) might be useful for assessing myocardial viability and residual ischemia in the infarct zone very early after reperfusion. Methods and results Fifteen open-chest dogs had left anterior descending coronary artery occlusion for 60 minutes, followed by full reperfusion (group 1, n = 8) or reperfusion through a residual critical stenosis (group 2, n = 7). Tl-201 was injected at rest 45 minutes after reperfusion, and initial and 2-hour redistribution images were acquired. Tc-99m sestamibi was then injected during vasodilator stress, followed by imaging. Infarct size was similar in both groups (risk area, 21% ± 4% vs 22% ± 3%). Rest Tl-201 defect count ratios (left anterior descending coronary artery/left circumflex artery) were comparable (0.71 ± 0.03 vs 0.74 ± 0.02) and reflected infarct size. With vasodilation, Tc-99m sestamibi defect count ratio in group 1 (0.71 ± 0.02) was comparable to rest Tl-201 and was significantly greater than in group 2 (0.62 ± 0.02) with residual stenoses ( P < .01). Although vasodilator Tc-99m sestamibi imaging unmasked the presence of residual stenoses, Tc-99m sestamibi uptake underestimated their functional severity (flow ratio, 0.38 ± 0.03). Conclusions Dual-isotope imaging very early after reperfusion may have limited utility for detecting residual stenoses in the infarct zone. Underestimation of the flow disparity by Tc-99m sestamibi may make the detection of stenoses more difficult, and impaired flow reserve after ischemic insult may complicate the detection of fully reperfused segments.

Quantitative regional wall motion analysis with early contrast ventriculography for the assessment of myocardium at risk in acute myocardial infarction

Background Several techniques have been used to quantify the myocardium at risk, including measurement of regional ventricular function with contrast ventriculography and measurement of perfusion defect size with tomographic technetium-99m-sestamibi imaging. This study evaluates the correlation between these 2 techniques. Methods Twenty-three patients with angiographically documented coronary occlusion and acute myocardial infarctions (10 anterior, 13 inferior) were studied. All patients had contrast left ventriculography at the time of their acute angiogram before any revascularization therapy. Regional wall motion parameters measured with the centerline method were the severity, circumferential extent, and global circumferential extent of hypokinesis and the mean standardized motion in predefined areas. Technetium-99m-sestamibi was injected before reperfusion therapy with measurement of the myocardium at risk using single photon emission computed tomography imaging. Results The tomographic sestamibi-measured myocardium at risk was significantly greater for anterior infarctions compared with inferior infarctions (40% ± 18% vs 14.0 ± 8.5%, P = .0001). The only parameter of regional wall motion to show a significant difference by infarct location was global circumferential extent of hypokinesis (43% ± 25% vs 22% ± 15%, P = .02). The other parameters were not significantly different between anterior and inferior myocardial infarctions. For anterior infarctions, these parameters of regional wall motion correlated with myocardium at risk assessed with sestamibi: global circumferential extent of hypokinesis ( r = .88, P < .01), circumferential extent of hypokinesis ( r = .78, P < .01), mean standardized motion in predefined areas ( r = –.74, P < .05), and severity of hypokinesis ( r = –.70, P < .05). For inferior infarctions, there was no significant correlation between any of these parameters of regional wall motion and myocardium at risk assessed with sestamibi imaging. Conclusion The assessment of regional ventricular function with contrast ventriculography correlates with the area of myocardium at risk measured with tomographic technetium-99m-sestamibi for anterior, but not for inferior, myocardial infarctions. Therefore, these parameters of regional wall motion are a poor measure of the efficacy of reperfusion therapies.

In vivo detection of resistance to anthracycline based neoadjuvant chemotherapy in locally advanced and inflammatory breast cancer with technetium-99m sestamibi scintimammography

Neoadjuvant chemotherapy (NACT) is the treatment of choice in patients (pts) with locally advanced (LABC) and inflammatory breast cancer (IBC). To evaluate the role of Tc-99m sestamibi imaging in the prediction of response to NACT and in the in vivo functional detection of intrinsic or acquired chemoresistance, 24 female pts with LABC (n=21) or IBC (n=3) were prospectively studied. Tc-99m scintimammography was performed 1-3 days before treatment (first) and 2-5 days after the completion (second) of NACT (epirubicin and cyclophosphamide for LABC and doxorubicin and vinorelbine for IBC). Three planar images (2 lateral prone and one anterior supine, 10 min/each) were obtained 10 min postinjection and a lateral prone image (10 min) of the affected breast (B) was obtained at 4 h. To calculate the tumor to normal B ratio (TBR), 2 identical irregular regions of interest (ROIs) were drawn around the tumor (T) and in adjacent ipsilateral normal B on both early (E) and delayed (D) prone lateral images. The TBR was obtained as the ratio of the mean counts per pixels in the 2 ROIs. Then Tc-99m sestamibi retention index (RI) in the T was determined by dividing the D-TBR by the E-TBR. Afterwards, NACT response was assessed pathologically or clinically in inoperable disease. Scintigraphic sensitivity for correct prediction of T presence after NACT was 81% (17/21), whereas specificity for correct prediction of T absence was 100% (3/3). In LABC, 3 patients had a pathological complete response: first RI was high (>0.56) in all 3, while no T uptake was visible on the second scintigraphy. Eighteen patients did not show a pathological complete response: in 5, both first and second RI were low (</=0.56); 9 had high first RI but low second; 4 had high first RI and no T detected on the second scan. In IBC, the only patient with a clinical complete response had both first and second RI high, whereas the 2 non-responsive pts had both first and second RI low. These results indicate that Tc-99m sestamibi scintimammography can predict LABC and IBC response to NACT. The scintigraphy protocol, including 2 studies before and after NACT, is useful for detecting intrinsic and acquired chemoresistant BC in vivo, which is important for planning therapy and predicting prognosis.

Sestamibi Imaging to Triage Patients With Acute Chest Pain—Reply

Sestamibi Imaging to Triage Patients With Acute Chest Pain—Reply

The False Negative Technetium-99m-Sestatnibi Scan in Patients with Primary Hyperparathyroidism: Correlation with Clinical Factors and Operative Findings

False negative (FN) results limit the efficacy of technetium-99m-sestamibi scanning for parathyroid localization. We determined the incidence of FN results and attempted to correlate it with clinical and operative findings. One hundred forty-six patients underwent parathyroidectomy; 89 had primary hyperparathyroidism (76 single adenoma and 13 multiglandular disease) and underwent sestamibi scanning. The false negative rate was 22 per cent with an overall sensitivity of 77 per cent and a positive predictive value of 99 per cent. Patients with single adenomas were more likely to have a true positive scan than those with multiglandular disease [83% vs 38%; odds ratio (OR) = 7.754, 95% confidence interval (CI) = 2.184–27.524; P ≤ 0.0001]. Inferior adenomas (90% vs 59%; OR = 6.261,95% CI = 2.037–19.243; P ≤ 0.0001) and larger adenomas (1422.3 ± 1576.2 vs 474.6 ± 193.2 g; P ≤ 0.0001) were more likely to be detected by sestamibi imaging. Patients with normal preoperative calcium levels were more likely to have an FN sestamibi scan. Sestamibi parathyroid imaging is limited by a 22 per cent FN rate and is less accurate for detecting abnormal parathyroid tissue in patients with small adenomas, multiglandular disease, superior adenomas, or preoperative normocalcemia.

Comparison of the predischarge exercise thallium-201 perfusion defect after myocardial infarction with myocardium at risk measured during acute infarction with technetium-99m sestamibi imaging

Background Exercise thallium-201 imaging provides a noninvasive estimate of the amount of myocardium presumed to be at risk of infarcting should a complete occlusion of the coronary stenosis occur. The relationship between the size of the exercise thallium perfusion defect and the extent of myocardium supplied by a diseased coronary artery has not been established. This study evaluates that presumed correlation. Methods Patients were injected intravenously with technetium-99m sestamibi during acute myocardial infarction before thrombolysis or conventional therapy to quantify the myocardium at risk. Twenty-six patients who underwent risk-area assessment subsequently underwent clinically driven, predischarge, submaximal exercise imaging with thallium-201. The exercise testing was performed on day 7 ± 2 days. A conventional polar map display was used to quantify the perfusion defect. Results The myocardium at risk determined by technetium-99m sestamibi at the time of infarction was 30% ± 20% of the left ventricle. The mean exercise thallium-201 defect was 34% ± 22% of the left ventricle. The exercise defect tended to be slightly larger than the myocardium at risk (4% ± 10% of the left ventricle, P =.05). There was a close correlation between the 2 measurements (r = 0.89, SE = 9.4, P <.0001). Conclusions This study shows a close correlation between the myocardium “at risk” assessed acutely by technetium-99m sestamibi and the “presumed at-risk area” determined by thallium-201 imaging on predischarge exercise testing. This finding supports the concept that the size of the exercise thallium defect caused by coronary stenosis indicates the likely size of a myocardial infarction resulting from occlusion of that stenosis. (Am Heart J 2003;145:357-63.)

Prediction of Left Ventricular Functional Recovery by Dobutamine Echocardiography, F-18 Deoxyglucose or 99mTc Sestamibi Nuclear Imaging in Patients with Chronic Myocardial Infarction

Background: Currently, several modalities are available to predict viability, however, studies comparing various modalities validated by functional recovery after revascularization are scarce. This study analyzed the relative merits of low-dose dobutamine echocardiography, F-18 deoxyglucose (FDG) positron emission tomography (PET) and ^99mTc sestamibi single-photon emission computed tomography to predict functional recovery after revascularization in patients with chronic myocardial infarction. Methods: Patients with chronic coronary occlusion (duration: 3.1 ± 4.8 years) and impaired left ventricular function (ejection fraction: 42 ± 13%) underwent low-dose dobutamine echocardiography (20 µg/kg/min), FDG-PET and ^99mTc sestamibi imaging before revascularization. Revascularization was performed irrespective of any viability data. Follow-up angiography was obtained 4.8 ± 2.5 months after revascularization. Results: Viability analysis was performed in 34 patients with patent target vessel at follow-up, of whom 9 (27%) exhibited functional recovery on left ventricular angiography. For dobutamine echocardiography, improvement of ≧2 adjacent akinetic segments resulted in improved sensitivity of 89% and specificity of 80% to predict functional recovery. For glucose metabolism, FDG uptake >55% was an optimal threshold yielding a sensitivity of 89% and a specificity of 68%. With respect to perfusion, ^99mTc sestamibi uptake >60% was the best cutoff resulting in a sensitivity and a specificity of 56 and 88%, respectively. A concordant match of FDG >55% and of ^99mTc sestamibi >50% resulted in optimized sensitivity (78%) and specificity (80%) with dual imaging. Conclusions: Recovery of chronically dysfunctional myocardium can be predicted with high accuracy by stimulation of contractile reserve or by concordant match of preserved glucose metabolism and residual perfusion.

Impact of revascularization and myocardial viability determined by nitrate-enhanced Tc-99m sestamibi and Tl-201 imaging on mortality and functional outcome in ischemic cardiomyopathy

Background. Nitrate-enhanced perfusion imaging has been shown to detect viability in dysfunctional myocardium, but nitrate-enhanced technetium 99m sestamibi has not been compared with nitrate-enhanced thallium 201. Methods and Results. Fifty-six patients with ischemic cardiomyopathy and heart failure (New York Heart Association classes II-IV) were scheduled for revascularization. Through use of a matching 12-segment model, nitrate-enhanced Tl-201 and Tc-99m sestamibi uptake at rest was assessed by 2 sets of blinded investigators. All single photon emission computed tomography data sets were read separately. Additional exercise Tc-99m sestamibi single photon emission computed tomography was performed on a separate day. Myocardial viability was thought to be present when the tracer uptake score was less than 3 (normal, 0; absent, 4). Of the 56 patients scheduled to undergo revascularization, only 23 (41%) underwent the procedure and the remainder continued medical therapy. Functional assessment by rest echocardiography was performed at 21 ± 8 months, and survival was determined at 40 ± 18 months. The baseline clinical and hemodynamic parameters were similar in the revascularization (n = 23) and medical therapy (n = 33) groups. Perfusion scores with nitrate-enhanced Tl-201 and Tc-99m sestamibi were similar in dysfunctional segments. Stress Tc-99m sestamibi reversible defects predicted significant improvement in left ventricular function compared with those without defects (P < .01) after revascularization. Cox regression model showed that when at least 5 reversible segments were viable, revascularization produced greater improvements in New York Heart Association class, a better trend toward survival (P = .07 for Tl-201 and P = .06 for Tc-99m), and a significantly greater impact on reverse remodeling. Conclusions. Myocardial viability determined by nitrate-enhanced Tl-201 and myocardial viability determined by Tc-99m sestamibi are equivalent for predicting functional improvements, remodeling, and survival after revascularization in patients with ischemic cardiomyopathy. (J Nucl Cardiol 2002;9:454-62)

Release Characteristics of Cardiac Biomarkers and Ischemia-modified Albumin as Measured by the Albumin Cobalt-binding Test after a Marathon Race

Numerous studies have monitored the appearance of both cardiac and skeletal muscle proteins and enzymes after short- and long-term exercise regimens. Both animal and human exercise models have attempted to determine whether the stress of long-duration exercise, such as a marathon race (42.2 km), could cause myocardial necrosis and the release of cardiac-specific proteins, such as cardiac troponin I (cTnI) or T (cTnT) (1)(2)(3)(4). In a rat animal model, the severe stress of swimming for 5 h caused microscopic evidence of myocardial necrosis, which led to substantially increased serum cTnT concentrations (1). However, in a less stressful regimen of 1–3 h of swimming, no evidence of ischemic injury and only very minor alterations in serum cTnT concentrations were detected. Middle-aged male marathon runners had increases in inflammatory and prothrombotic markers within 4 h after completion of a race (5). Increases in cTnI were also observed (6). However, no evidence of microinfarction was found by sestamibi imaging, nor was evidence of left ventricular dysfunction found by B-natriuretic peptide testing (6). Ischemia-modified albumin (IMA), measured by the albumin cobalt-binding (ACB) test (7), is reported to predict subsequent cTnI results for patients presenting with symptoms of acute coronary syndromes. Furthermore, studies that included percutaneous transluminal coronary angioplasty as a model of transient myocardial ischemia have demonstrated that serum IMA concentrations, as measured by the ACB test, were increased very early after an ischemic event (8); thus, IMA may be a very early indicator of myocardial ischemia before necrosis. To test this hypothesis in healthy persons at very low risk for cardiac disease but at high risk for skeletal muscle damage, we studied the appearance and clearance characteristics of the IMA marker compared with cTnI, cTnT, and myoglobin in runners after a marathon race. Nineteen Caucasian runners, …

High-dose dipyridamole and gated sestamibi SPECT imaging provide diagnostic resting and stress ejection fractions useful for predicting extent of coronary artery disease.

A decline in ejection fraction at stress compared with rest images has been associated with increased severity of coronary artery disease (CAD) and suggests a poorer prognosis. Myocardial perfusion imaging (MPI) using high-dose dipyridamole (HDD) has been shown to more accurately detect CAD than either standard dose dipyridamole (SDD) or exercise-induced stress (EST), but has not been looked at to determine its usefulness in detecting changes in stress and rest ejection fractions. To determine the relationship between changes in left ventricular ejection fraction (LVEF) and the severity of CAD, 36 Individuals underwent gated single photon emission computed tomography (SPECT) MPI using HDD. In each case resting and stress LVEFs were determined along with MPI results. Subjects with single-vessel CAD demonstrated an increase in LVEF from 77.8% (sd +/-8.8%) to 85.6% (sd +/-8.4%) resulting in a statistically significant increase in LVEF of 7.8% (p = 0.009). Patients with two-vessel disease showed a smaller increase from 73.2% (sd + 8.3%) to 79.8% (sd + 9.8%) following HDD stress. This increase was statistically (p = 0.008) significant. Patients with triple-vessel CAD showed a reduction in LVEF from 67.4% (sd +/-14.07) to 65.1% (sd +/-16.5%) which represented a decrease in LVEF of 2.7% and approached (p = 0.25) but did not reach statistical significance. Both the resting and stress LVEFs were statistically lower (p<0.05) in patients with triple-vessel CAD. Changes in resting LVEF (REF) and HDD pharmacologically induced stress LVEF (SEF) provide a valuable diagnostic marker as to the number of significantly diseased coronary arteries and can be acquired from gated SPECT sestamibi images.