Tc-99m sestamibi scanning in the preoperative localization of mediastinal parathyroid adenomas

We report on two patients with mediastinal parathyroid adenomas who underwent preoperative Tc-99m sestamibi scintigraphy. Excellent physical characteristics of technetium and slow washout of Tc-99m sestamibi made possible clear delineation of mediastinal parathyroid adenomas by Tc-99m sestamibi imaging.     

Comparison of Tc-99m sestamibi and Tl-201 gated perfusion SPECT

BACKGROUND: To determine the interpretability of gated thallium-201 perfusion SPECT compared with that performed by use of technetium-99m sestamibi (MIBI), 33 patients with prior myocardial infarction were studied. Patients received 22 to 30 mCi (814 to 1110 MBq) MIBI at peak stress, and a 15-minute gated SPECT acquisition was begun 30 to 40 minutes thereafter. On a subsequent day gated Tl-201 SPECT was acquired for 15 minutes, 4 hours after a resting 3.5 mCi (130 MBq) injection. SPECT was performed over a 180-degree arc by use of a 90-degree angled 2-detector camera. RESULTS: Gated studies were interpreted independently by 4 experienced physicians. Study quality was graded (0 = uninterpretable to 4 = excellent). Wall motion (0 = normal to 2 = akinetic/dyskinetic) and wall thickening (0 = normal to 2 = absent) were graded for each of 10 segments viewed in orthogonal planes. Left ventricular ejection fraction (LVEF) was calculated by use of software thus far validated only for MIBI. The average count density of mid-ventricular end-diastolic short axis tomograms with sestamibi was 3.47 times greater than with thallium. Mean study quality was 3.4 for MIBI and 1.8 for thallium (P < 10(-6)). No gated MIBI SPECTs, but 2 gated thallium studies (6%) were judged uninterpretable. Among interpretable scans, interobserver agreement (Kendall statistic) in assessing wall motion was 0.73 for MIBI and 0.66 for thallium (P = .01). For assessing wall thickening, the Kendall statistic was 0.73 for MIBI and 0.69 for thallium (P = .05). Correlation (r) of LVEFs was 0.91, SEE = 6.4. CONCLUSIONS: We conclude that gated thallium SPECT is inferior to MIBI because of much poorer image quality and somewhat poorer interobserver agreement among experienced physicians. However, LVEF can be determined reliably from gated thallium SPECT.     

Tc-99m sestamibi gated SPECT in patients with left bundle branch block

PURPOSE: The purpose of this study was to assess the diagnostic role of a Tc-99m sestamibi gated SPECT technique in patients with left bundle branch block (LBBB) without known coronary artery disease. MATERIALS AND METHODS: Twenty consecutive patients with constant complete LBBB were included. A same-day rest-stress protocol was used, and dipyridamole stress (14 patients) or treadmill exercise (6 patients) was applied. Electrocardiograph (ECG)-gated SPECT images were acquired 15 minutes after the administration of 0.31 mCi/kg Tc-99m sestamibi at peak stress. Regional myocardial perfusion was analyzed in relation to the cardiac cycle. RESULTS: Eleven of 14 patients who underwent a dipyridamole stress test had hypoactivity in the left anterior descending (LAD) artery territory in the ungated (summed) stress-rest images (abnormality ratio, 78%). On the ungated images, the abnormality was completely reversible in one patient (9%), partially reversible in five patients (46%), irreversible in two patients (18%), and reverse perfusion was identified in three patients (27%). Abnormality ratios of end-systolic and end-diastolic data were 93% and 29%, respectively. Conversely, the ungated rest-stress and end-systolic images of all the patients who performed treadmill exercise were abnormal despite the presence of normal or nearly normal end-diastolic myocardial perfusion. The angiographic findings correlated best with those of end-diastolic images. In 13 patients without coronary artery disease, normal or nearly normal regional perfusion was observed on end-diastole, but four patients with abnormal end-diastolic perfusion, which involved the LAD territory in all but one, had substantial coronary artery disease. The number of the involved segments was similar on the end-systolic and ungated data. Most of these artifactual defects were localized to the anteroseptal, septal, and inferoseptal segments. CONCLUSIONS: These preliminary data indicate that end-diastolic images can significantly reduce artifactual defects in patients with LBBB. The resolution of an LBBB pattern on end-diastolic data would significantly improve the diagnostic role of myocardial perfusion studies in these patients.     

Multiple hepatic adenomas: Tc-99m RBC liver SPECT findings with pathologic correlation

A 24-year-old man with multiple hepatic masses incidentally detected by ultrasonography underwent Tc-99m RBC liver SPECT. SPECT images showed increased blood pooling mimicking hemangiomas in two of four masses or activity similar to normal liver in the others. The patient had a 3-year history of steroid therapy for rheumatoid arthritis. Computed tomography and magnetic resonance imaging showed multiple liver lesions. Angiography revealed three hypervascular and one hypovascular mass. Microscopic examination of the enucleated specimens disclosed hepatic adenomas with many dilated sinusoids in the masses showing blood pooling and fatty change, and adenomas without dilated sinusoids in the masses not showing blood pooling. This case report shows that the appearance of hepatic adenomas can vary on Tc-99m RBC liver SPECT, depending on whether dilated sinusoid and hepatic adenomas show blood pooling. This is one of the few examples of false-positive findings that can be mistaken for hemangioma.     

Long-term prognosis after a normal exercise stress Tc-99m sestamibi SPECT study

BACKGROUND: Patients with a normal stress technetium 99m sestamibi study were shown to have a favorable outcome at intermediate-term follow-up. However, long-term survival has not been studied. The aim of this study was to evaluate the incidence and predictors of mortality and cardiac events at long-term follow-up after a normal exercise stress sestamibi study.Methods and results We studied 218 patients (mean age, 53 +/- 10 years, 108 men) who had normal myocardial perfusion assessed by Tc-99m sestamibi single photon emission computed tomography at rest and during symptom-limited bicycle exercise stress test. Endpoints during a follow-up period of 7.4 +/- 1.8 years were hard cardiac events (cardiac death and nonfatal myocardial infarction) and all-cause mortality. During follow-up, 13 patients died of various causes (cardiac death in 1 patient). Ten patients had nonfatal myocardial infarction (a total of 11 hard cardiac events). By multivariate analysis, independent predictors of cardiac events were history of coronary artery disease (chi(2) = 5, P =.03) and lower exercise heart rate (chi(2) = 12, P =.001). Independent predictors of all-cause mortality were age (chi(2) = 4, P =.05) and exercise heart rate (chi(2) = 5, P =.03). The annual mortality rate was 0.6% in the first 5 years and 1.8% between the sixth and eighth years. The annual hard cardiac event rate was 0.7% in the first 5 years and 1.5% between the sixth and eighth years. Receiver operating characteristic curves identified an exercise heart rate lower than 130 beats/min as the cutoff value that separated patients with regard to their risk for mortality and hard cardiac events. CONCLUSIONS: It is concluded that the annual mortality and cardiac event rate is less than 1% during 5-year follow-up after a normal exercise sestamibi study. Therefore repeated testing would not be required unless there is a change in symptoms. Follow-up should be closer in patients with a history of coronary artery disease and in those who fail to achieve an exercise heart rate of 130 beats/min or greater.     

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.     

Discordance between dipyridamole stress Tc-99m sestamibi SPECT and coronary angiography in patients with Kawasaki disease

BACKGROUND: Kawasaki disease is an acute vasculitis syndrome of unknown etiology that mainly affects the coronary arteries. The purpose of this study was to assess the agreement between dipyridamole stress technetium 99m sestamibi single photon emission computed tomography (SPECT) and coronary angiography in these patients. METHODS AND RESULTS: Forty-one consecutive patients (29 boys and 12 girls) who underwent coronary angiography were studied prospectively. Their ages at onset of the disease ranged from 2 months to 4.8 years (mean +/- SD, 1.9 +/- 1.3 years). Their ages at the time of the study ranged from 8 months to 15.3 years (6.2 +/- 4.4 years). The duration between symptom onset and the study ranged from 2 months to 12 years (4.3 +/- 4.0 years). All patients underwent dipyridamole stress Tc-99m sestamibi SPECT within 1 month of their angiographic studies. They were divided into 3 groups according to coronary angiography findings. Group A consisted of 2 patients (1 boy and 1 girl, aged 10.3 and 1.9 years, respectively) with coronary stenoses who also had aneurysms. Group B consisted of 10 patients (8 boys and 2 girls, aged 0.7-15.3 years [mean, 3.8 years]) with coronary aneurysms. Group C consisted of 29 patients (20 boys and 9 girls, aged 1.2-13.8 years [mean, 7 years]) with normal coronary angiograms. Two patients in group A (100%), 3 of 10 patients in group B (30%), and 19 of 29 patients in group C (65.5%) had myocardial perfusion defects. There was poor agreement between Tc-99m sestamibi SPECT and coronary angiography for detecting coronary stenoses (kappa = 0.07; P =.222) and aneurysms (kappa = -0.184; P =.158). CONCLUSION: Significant discordance exists between Tc-99m sestamibi SPECT and coronary angiography in patients with Kawasaki disease.     

Comparison of Tc-99m HMPAO fast SPECT with Tc-99m HMPAO conventional SPECT in patients with acute stroke.

Tc-99m HMPAO SPECT is more likely to detect a stroke in early stages than CT. However, a conventional HMPAO SPECT study takes at least 30 minutes to complete. This paper compares fast Tc-99m HMPAO SPECT scans and conventional Tc-99m HMPAO SPECT scans with respect to spatial resolution and diagnostic efficacy in vitro and in a small series of patients, respectively. The spatial resolution of fast Tc-99m HMPAO SPECT did not match that of images obtained from conventional SPECT, though the difference proved to be of no clinical significance. Since fast SPECT requires only one-fourth to one-fifth the time necessary for conventional SPECT, it may be more suitable for investigating cases of acute stroke in critical clinical situations.     

Tc-99m sestamibi/F-18 FDG myocardial SPECT in Takayasu arteritis with coronary artery involvement

Coronary arteries may be involved in some patients with Takayasu arteritis. Evaluation of myocardial involvement due to coronary lesions may provide important information in the clinical management of these patients. We report Tc-99m sestamibi and F-18 FDG myocardial single photon emission computed tomography in 3 cases of such patients.     

Comparison of Tc-99m sestamibi SPECT with fractional flow reserve in patients with intermediate coronary artery stenoses

BACKGROUND: Myocardial single photon emission computed tomography (SPECT) is an established noninvasive method for the assessment of the functional significance of coronary artery stenoses. Intracoronary pressure measurements to determine fractional flow reserve (FFR) are increasingly performed during coronary angiography whenever an immediate decision regarding possible intervention is required. We hypothesized that the regional summed difference score (SDSr), reflecting reversible perfusion defects in the myocardial supply area of the FFR target vessel, would be the best predictor of an abnormal FFR in patients without prior myocardial infarction. Otherwise, a regional summed stress score (SSSr) should be the best predictor of an abnormal FFR in patients with prior myocardial infarction for different patient subgroups with coronary artery disease. METHODS AND RESULTS: In this study 50 patients (mean age, 65 +/- 9.1 years; 18 women) with coronary artery disease and a 50% to 75% coronary stenosis (target vessel) were prospectively investigated. Dobutamine myocardial SPECT was performed as a single-day stress/rest protocol by use of technetium 99m sestamibi. For image interpretation, semiquantitative analysis was conducted by calculating SSSr and SDSr. Within 8 (+/-14.9) days, coronary angiography was performed and FFR was calculated by use of a pressure wire (normal FFR, > or = 0.75). The mean FFR of all patients was 0.78 +/- 0.14. Of 50 patients, 17 had an FFR lower than 0.75 in the target vessel. Receiver operating characteristic analysis identified an SDSr of 1 or greater and an SSSr of 3 or greater as the best threshold values for predicting ischemic FFR. Sensitivity, specificity, and negative and positive predictive values of SDSr and SSSr for the detection of FFR values lower than 0.75 in the target vessel were 80%, 76%, 53%, and 92%, respectively, and 70%, 93%, 78%, and 90%, respectively, in patients without prior myocardial infarction and 57%, 50%, 67%, and 40%, respectively, and 100%, 50%, 78%, and 100%, respectively, in patients with prior myocardial infarction. Weak correlation was found between the single values of FFR with both SDSr and SSSr for the different patient subgroups. CONCLUSION: Among the dobutamine myocardial scintigraphy variables studied, SDSr was the best predictor of an abnormal FFR (cutoff value of 0.75) in patients without prior myocardial infarction. As assumed, SSSr was the best predictor of an abnormal FFR in patients with prior myocardial infarction in the target region.     

Clinical correlates of Tc-99m sestamibi lung uptake

BACKGROUND: Increased lung uptake of thallium 201 during myocardial perfusion scintigraphy is related to severe coronary artery disease (CAD), but a similar relationship for technetium 99m sestamibi has not been clearly established. METHODS AND RESULTS: Resting and stress lung-heart ratios (LHR) were retrospectively determined in 96 patients who underwent Tc-99m sestamibi stress testing and coronary angiography within 4 months of each other. A semiquantitative CAD severity score (CADSS) was derived from the coronary angiogram. Left ventricular (LV) function was assessed in a subgroup of 42 subjects. CADSS of 24 or higher was associated with increased stress LHR compared with angiographically normal individuals (P =.009). Patients with severely impaired LV function also had a higher mean stress LHR than those with normal LV function (P =.01). Stress LHR was significantly greater than resting LHR in patients with coronary disease (0.32 +/- 0.07 vs 0.30 +/- 0.07; P =.003) and impaired LV function (0.35 +/- 0.08 vs 0.31 +/- 0.07; P <.02). CADSS correlated with stress, but not resting, LHR (P =.006), whereas the degree of LV dysfunction correlated with both resting (P =.046) and stress (P =.004) LHR. Left anterior descending (P =.017) and left main (P =.03) stenoses were independent predictors of increased stress LHR. CONCLUSIONS: An increase in stress Tc-99m sestamibi lung uptake is a marker for severe CAD. Correlation of stress LHR, but not resting LHR, with CAD severity supports exercise-induced pulmonary congestion as the underlying mechanism.     

Parathyroid adenomas evaluated by Tl-201/Tc-99m pertechnetate subtraction scintigraphy and high-resolution ultrasonography

Thallium-201/technetium-99m pertechnetate subtraction scintigraphy of the parathyroid glands was performed in a prospective study of 33 patients who had undergone bilateral neck exploration for elevated serum calcium and serum parathyroid hormone levels. In 31 cases, the Tl-201/Tc-99m subtraction technique yielded an overall sensitivity of 81%, specificity of 99%, and accuracy of 94% for identifying solitary parathyroid adenomas. Tl-201/Tc-99m subtraction scintigraphy correctly identified 73% of parathyroid adenomas weighing less than 499 mg, 79% of those weighing 500-1,499 mg, and 100% of adenomas weighing more than 1,500 mg. In a subgroup of 24 patients with solitary parathyroid adenomas who underwent both scintigraphy and high-resolution sonography, the sensitivity, specificity, and accuracy of both procedures were similar.