Enhanced detection of reversible perfusion defects by Tc-99m sestamibi compared to Tc-99m tetrofosmin during vasodilator stress SPECT imaging in mild-to-moderate coronary artery disease.

OBJECTIVES: We prospectively compared dipyridamole single-photon emission computed tomography (SPECT) imaging with Tc-99m sestamibi and Tc-99m tetrofosmin for the detection of reversible perfusion defects in patients with mild-to-moderate coronary artery disease. BACKGROUND: Tc-99m tetrofosmin has a lower first-pass myocardial extraction fraction compared to Tc-99m sestamibi and thus could underestimate mild perfusion defects. METHODS: Eighty-one patients with 50% to 90% stenosis in one or two major epicardial vessels without previous myocardial infarction, and seven with <5% probability of coronary artery disease underwent dipyridamole SPECT imaging with both agents. The SPECT data were analyzed quantitatively. RESULTS: Tc-99m sestamibi detected reversible perfusion defects in a greater number of segments (total 363 and 285, p < 0.001, and mean +/- SD, 2.2 +/- 3.0 and 1.8 +/- 2.5 per patient, p = 0.008, for Tc-99m sestamibi and Tc-99m tetrofosmin, respectively), demonstrated a larger extent of perfusion defect (mean +/- SD, 15.8% +/- 12.3% and 12.0% +/- 11.4%, p < 0.03, for Tc-99m sestamibi and Tc-99m tetrofosmin, respectively) and more often correctly identified patients with disease in more than one coronary artery (p = 0.02). There was better defect contrast with Tc-99m sestamibi (defect/normal wall count ratios were 0.60 +/- 0.15 vs. 0.73 +/- 0.14 for Tc-99m sestamibi and Tc99m tetrofosmin, respectively, p = 0.01, for reversible defects seen in identical segments with both agents; and 0.73 +/- 0.16 vs 0.79 +/- 0.17, respectively, p <0.01, for reversible defects detected with either agent alone). There was no significant difference in diagnostic sensitivity or image quality. CONCLUSIONS: These differences between two commonly used tracers may have significant diagnostic and prognostic implications.

Comparative diagnostic accuracy of Tl-201 and Tc-99m sestamibi SPECT imaging (perfusion and ECG-gated SPECT) in detecting coronary artery disease in women.

OBJECTIVES: This prospective study was conducted in 115 women to directly compare the sensitivity and specificity of thallium-201 (Tl-201), technetium-99m (Tc-99m) sestamibi perfusion and Tc-99m sestamibi electrocardiographic (ECG)-gated single-photon emission computed tomographic (SPECT) studies for detection of coronary artery disease (CAD). BACKGROUND: Data on the comparative diagnostic accuracy of Tl-201 and Tc-99m sestamibi perfusion imaging for the detection of CAD, specifically in women, are very limited. METHODS: Eighty-five patients with suspected CAD, scheduled for coronary angiography, and 30 volunteers with a pretest likelihood of < or = 5% for CAD were evaluated. Within 1 week, each patient underwent Tl-201 and Tc-99m sestamibi SPECT imaging procedures (both perfusion and gated SPECT imaging). Treadmill stress testing was used in 78 patients and dipyridamole in the remaining 37 patients. All images were interpreted by three observers in a blinded manner (consensus reading). Technetium-99m sestamibi SPECT studies were read without and then with ECG gating. Technetium-99m sestamibi gated SPECT studies were used to differentiate scar tissue from soft tissue attenuation artifact. RESULTS: The overall sensitivities for detecting > or = 50% and > or = 70% stenoses were 75.0% and 84.3%, respectively, for Tl-201, and 71.9% and 80.4%, respectively, for Tc-99m sestamibi perfusion studies (p = 0.48). The specificity for lesions > or = 50% was 61.9% for Tl-201 and 85.7% for Tc-99m sestamibi perfusion (p = 0.07), whereas for lesions > or = 70% it was 58.8% for Tl-201 and 82.4% for Tc-99m sestamibi perfusion (p = 0.01). When the 34 patients with a normal coronary angiogram were added to the group of 30 normal volunteers, the "specificity" for lesions > or = 70% was 67.2% for Tl-201, 84.4% for Tc-99m sestamibi SPECT perfusion (p = 0.02) and 92.2% for Tc-99m sestamibi gated SPECT (p = 0.0004). CONCLUSIONS: Both Tl-201 SPECT and Tc-99m sestamibi SPECT perfusion studies had a similar sensitivity for the detection of CAD in women. However, Tc-99m sestamibi SPECT perfusion imaging shows a significantly better specificity, which is further enhanced by the use of ECG gating.

Incomplete redistribution in delayed thallium-201 single photon emission computed tomographic (SPECT) images: an overestimation of myocardial scarring.

To determine if incomplete redistribution at 4 h in exercise tomographic thallium-201 studies is always due to a myocardial scar, 141 patients were evaluated before and after a total of 160 successful percutaneous transluminal coronary angioplasty procedures. Thallium studies were analyzed using polar "bull's-eye" maps. For both immediate and delayed images, abnormalities were quantified as a thallium score by calculating a standard deviation-weighted sum of pixels greater than 2.5 SD below gender-matched normal limits. One hundred forty-four of 160 studies indicated abnormalities before angioplasty. Of these 144, incomplete redistribution occurred in 111 (77%): 16 (14%) in patients with and 95 (86%) in patients without prior Q wave myocardial infarction. After angioplasty, improvement in delayed image score occurred in 8 (50%) of 16 patients with prior infarction and 72 (76%) of 95 patients without prior infarction (p less than 0.05). After angioplasty, delayed images were normal in 1 (6%) of 16 patients with prior infarction and 32 (34%) of the 95 without (p less than 0.05). Before angioplasty, delayed image scores were positively correlated with scores in the immediate postexercise images in patients with (r = 0.84) and those without (r = 0.69) prior infarction. To determine if additional delayed images could help differentiate scar from ischemia, an 8 to 24 h delayed image was obtained in each of 40 other patients with incomplete redistribution at 4 h. Of 28 patients without prior infarction, 15 had no redistribution, and 13 had further redistribution at 8 to 24 h.

Restenosis after transluminal coronary angioplasty detected with exercise-gated radionuclide ventriculography.

Forty-one patients were evaluated with exercise-gated radionuclide ventriculography before and within 4 days after successful transluminal coronary angioplasty and 4 to 12 months later. Patients were subgrouped according to the degree of restenosis demonstrated angiographically at 4 to 12 months (Group I [n = 23]: less than or equal to 20%; Group II [n = 10]: greater than 20% but less than 50%; Group III [n = 8]: greater than or equal to 50%). Patients with abnormal findings on gated radionuclide ventriculography (less than 5 point increase in ejection fraction or wall motion deterioration) early after angioplasty were eventually found to have a greater degree of restenosis than were patients with normal findings (41.2 +/- 30.3 versus 19.0 +/- 25.4% restenosis, p less than 0.0001). The accuracy of abnormal radionuclide ventriculography in predicting 50% or greater restenosis was 73% immediately after angioplasty and 77% at the time of follow-up angiography. Gated radionuclide ventriculographic results were abnormal in 5% of Group I patients compared with 75% of Group III patients (p less than 0.01) early after angioplasty; at late follow-up, they were abnormal in 27% of Group I patients compared with 88% of Group III patients (p less than 0.01). Group I patients had a greater increase in ejection fraction than did Group III patients at early (+11.3 +/- 7.5 versus + 3.5 +/- 6.5 points, p less than 0.01) and late (+11.8 +/- 7.8 versus -1.9 +/- 8.7 points, p less than 0.0005) follow-up. It is concluded that gated radionuclide ventriculography is useful in predicting coronary restenosis after transluminal coronary angioplasty.

Sex steroids and bone density in premenopausal and perimenopausal women.

Bone density begins to decline in women before menopause, and the degree of bone loss is variable. We performed a cross-sectional analysis on the entry data of a 5-yr prospective study of risk factors for osteoporosis to determine the correlation of bone density with serum sex steroid concentrations and body weight. We studied 292 healthy white women, aged 35-50 yr, who were menstruating regularly or had had menses in the past 12 months. Blood samples were drawn in the early follicular phase for estradiol (E2), testosterone (T), dehydroepiandrosterone sulfate, and sex hormone-binding globulin (SHBG). Free levels of E2 (FE2) and T (FT) were calculated based on total T and E2, SHBG, and albumin levels. Women were classified as premenopausal (FSH, less than 12 U/L) and perimenopausal (FSH greater than or equal to 12 U/L; n = 46; 16%). Bone density was measured by dual photon absorptiometry of the lumbar spine (L2-L4) and hip and by single photon absorptiometry of the wrist. Perimenopausal women were older than premenopausal women (45.5 +/- 3.5 and 41.0 +/- 3.9 yr, respectively), but did not differ in height or weight. While bone density did not correlate with age in each group, perimenopausal women had significantly lower bone density at the L2-L4 and femoral neck (L2-L4, 1.18 +/- 0.14 in perimenopausal and 1.24 +/- 0.12 g/cm2 in premenopausal women; femur, 0.84 +/- 0.11 in perimenopausal and 0.90 +/- 0.11 g/cm2 in premenopausal women; P less than 0.005). Body weight showed the strongest positive correlation with bone density. Log FT, percent FT, and FE2 percent correlated positively with bone density, even after controlling for weight. Log SHBG was negatively correlated with bone density in premenopausal women at the hip and wrist after controlling for weight. FSH was inversely correlated with bone density, and E2 and T were lower in perimenopausal than premenopausal women. These data suggest that women who are still menstruating may have relative deficiencies in both E2 and T, with reduced bone densities as a consequence.

Exercise supplementation of dipyridamole for myocardial perfusion imaging.

The substitution of intravenous dipyridamole for symptom-limited treadmill exercise has provided a non-invasive means to diagnose coronary artery disease with 201Tl scintigraphy in patients unable to adequately exercise. Limitations of dipyridamole/thallium imaging are primarily due to suboptimal image quality secondary to hepatic tracer concentration and decreased test sensitivity in patients who are dipyridamole "non-responders." Low-level treadmill exercise supplementation improves image quality, whereas handgrip has little, if any, benefit. The effect of low-level exercise in augmenting coronary blood flow is unknown and reports regarding the effect of handgrip are conflicting. The diagnostic benefit of these maneuvers in improving test sensitivity and decreasing the number of "non-responders" has not been documented. The combination of maximal, symptom-limited treadmill exercise and intravenous dipyridamole is a theoretically attractive option to improve overall test sensitivity, but the physiologic consequences and potential side effects should be more thoroughly investigated.

How to detect and avoid myocardial perfusion SPECT artifacts.

Although myocardial perfusion imaging with SPECT is an accurate and reliable diagnostic study, artifacts must be avoided, or detected and corrected, to minimize the rate of false-positive results. Common sources of artifacts are nonuniformity in gamma camera detectors, center of rotation errors, misaligned cameras on multidetector scanner systems, errors in image reconstruction, patient motion, radiotracer uptake in nontarget organs and attenuation. Some of these artifacts can be avoided by quality control of instrumentation and by imaging the patient in a prone rather than supine position to separate radiotracer activity from the target and nontarget organs and to reduce the effect of inferior wall attenuation. Other artifacts can be detected by careful image inspection and corrected by reprocessing. The best way to avoid artifacts is to pay very close attention to the technical factors of image acquisition and processing, and to be aware of attenuation factors.

Optimal specificity of thallium-201 SPECT through recognition of imaging artifacts.

Artifacts are produced in 201TI cardiac single photon emission computed tomography (SPECT) imaging because of a variety of causes including soft-tissue attenuation, overlying abdominal viscera, variable myocardial thickness, left bundle branch block, cardiac rotation, patient motion, and technical errors. Careful attention to quality control, utilization of motion detectors, and familiarization with potential artifacts will improve the specificity and diagnostic accuracy of 201TI SPECT for coronary artery disease.

Using gated technetium-99m-sestamibi SPECT to characterize fixed myocardial defects as infarct or artifact.

UNLABELLED: Perfusion-scan fixed defects may result from soft tissue attenuation, decreasing test specificity for coronary disease and myocardial infarction (MI). Gated 99mTc-sestamibi SPECT may help differentiate MI from artifact since fixed defects with decreased function (wall motion and thickening) probably represent MI, whereas attenuation artifacts either have normal function or at least do not demonstrate markedly reduced function. METHODS: Ungated resting and gated stress 99mTc-sestamibi SPECT was performed in 551 consecutive patients referred for evaluation of coronary disease. From resting and summed gated stress images, 180 patients (33%) were identified with isolated fixed defects. Function of the defects was assessed subjectively from gated stress images and results were correlated with clinical (history and/or ECG Q-waves) evidence of MI. RESULTS: Of 102 patients with fixed defects and clinical MI, 98 (96%) had abnormal defect function. Of 78 patients with no clinical MI, 18 (23%) had decreased function of the defect, possibly indicating silent MI. In 60 of the 78 patients (77%) with no clinical MI, defect function was normal. Because most (91%) of fixed defects with normal systolic function occurred in women with anterior fixed defects (48%) or men with inferior fixed defects (43%), these were most likely attenuation artifacts. By reclassifying patients with fixed defects and normal function as normal, patients with unexplained fixed defects (no clinical MI) decreased from 14% to 3%. CONCLUSION: Gating provides a valuable adjunct to 99mTc-sestamibi SPECT in characterizing fixed defects and potentially improving test specificity.

Left ventricular ejection fraction assessed from gated technetium-99m-sestamibi SPECT.

By means of ECG gating of tomographic (SPECT) 99mTc-sestamibi (MIBI) images, myocardial perfusion and wall thickening have been evaluated after a single tracer injection. To determine if left ventricular ejection fraction (LVEF) can also be measured from gated MIBI SPECT, 30 patients 1 wk to 6 mo after myocardial infarction (MI) received 22-30 mCi 99mTc-MIBI during treadmill exercise. Eight frame per cardiac cycle gated MIBI 180 degrees SPECT was performed 60 min thereafter. Using 6.4-mm thick mid-ventricular vertical and horizontal long-axis slices from R-wave triggered end-diastolic and end-systolic frames, two independent observers manually drew endocardial borders at a count level of 34% of the maximum. LVEF was computed by the Simpson's rule method, corrected for the average point spread function of the SPECT camera. Results were correlated with LVEF determined from planar gated 99mTc-blood-pool studies performed within 4 days. LVEFs calculated from gated MIBI SPECT ranged from 0.21 to 0.73 and correlated linearly with gated blood-pool values (correlation coefficients ranged from 0.79 to 0.88; interobserver variability r = 0.75; intraobserver reproducibility r = 0.75). We conclude that in patients with MI resting LVEF can be determined from gated MIBI SPECT, thereby considerably augmenting the technique's diagnostic and prognostic value.

Thallium-201 SPECT in coronary artery disease patients with left bundle branch block.

Fourteen patients with left bundle branch block (LBBB) underwent immediate postexercise and 3-hr delayed 201Tl single photon emission computed tomography (SPECT) with quantitative analysis using bullseye polar maps. Test performance in detecting individual coronary artery stenosis greater than or equal to 50% demonstrated 100% sensitivity. Specificity was 100% for circumflex stenosis, 78% for right coronary stenosis, but only 10% for left anterior descending coronary stenosis. This very low specificity was due to the fact that 3/4 (75%) patients with left anterior descending stenosis and also 9/10 (90%) patients with normal left anterior descending coronary arteries had immediate septal perfusion defects with redistribution in all cases at 3 hr. Septal abnormalities were most marked in patients who achieved high peak heart rates (greater than 170 bpm). Thus, with LBBB, 201Tl SPECT is indeterminate for left anterior descending coronary disease.

Radionuclide computed tomography of the body using routine radiopharmaceuticals. II. Clinical applications.

A whole-body computed tomography system for single-photon emitters was used to investigate the clinical utility of this imaging modality. We have explored its application in brain, lung, liver, kidney, cardiac, bone, and gallium imaging in over 200 patients. Brain images demonstrated better lesion contrast than that in standard scintiphotos. Images of the lung and liver showed radionuclide distribution that was not readily apparent in standard scintiphotos. Moderate or strongly positive pyrophosphate myocardial images demonstrate the potential for infarct quantitation. ECG-gated cardiac blood-pool images in cross section, displayed in cine formate, permit evaluation of segmental motion of the free and septal walls of both ventricles. These results suggest significant clinical potential for this imaging modality using standard radiopharmaceuticals, but some increase in system sensitivity will likely be necessary to realize the full benefit of the technique.

Evaluation of right ventricular regional perfusion with technetium-99m-sestamibi SPECT.

To evaluate technetium-99m-sestamibi as a right ventricular perfusion imaging agent, 25 normal volunteers and 25 patients with suspected coronary disease were studied with both sestamibi and thallium-201 SPECT. All patients underwent cardiac characterization. Compared to thallium-201 images, visualization of the right ventricle was superior for sestamibi in all cases. After computer masking of the left ventricle, count profiles for each 6-mm right ventricular short-axis slice were extracted and plotted in a bull's-eye type polar map with images normalized to maximal right ventricular counts. On sestamibi right ventricular polar maps, 7 of 11 patients (64%) with right coronary stenosis had fixed or reversible inferior right ventricular defects. None of the 25 volunteers or patients without right coronary stenosis had right ventricular defects (true-negative rate = 100%). We conclude that sestamibi SPECT provides an accurate means to assess right ventricular regional perfusion, with data presentation and interpretation facilitated by the polar map display.

A review of cardiac imaging with sestamibi and teboroxime.

Overall, it is clear that the two new technetium-labeled compounds can provide diagnostic myocardial perfusion imaging both at stress (exercise and pharmacologic) and rest, but they have very different mechanisms of transport in comparison to each other and to thallium. Therefore, new imaging protocols will need to be developed and refined by practical experience as the use of these agents expands. Further investigative work needs to be done to optimize protocols and computer processing of images. In addition, special clinical situations will become associated with the use of these new compounds. Nuclear cardiology will continue to advance during this time of great changes and challenges if informational exchange on these topics continues to flourish and critical clinical trials are completed.

Simultaneous biplane first-pass radionuclide angiocardiography using a scintillation camera with two perpendicular detectors.

UNLABELLED: Generally performed in a single anterior or right anterior oblique (RAO) view, first-pass radionuclide angiocardiography (RNA) is limited due to its inability to evaluate septal and posterior wall motion. METHODS: Thirty-five patients undergoing stress/rest sestamibi SPECT (22 mCi/22 mCi 2-day protocol) underwent biplane RNA at the time of resting injection. The stress SPECT images (acquired with the patient at rest) were ECG-gated to evaluate resting regional myocardial wall thickening. By this means wall motion assessed by RNA was compared to the presence of a resting SPECT perfusion defect accompanied by a localized decrease in wall thickening. RESULTS: In 16 patients in whom both resting perfusion and wall thickening were normal one demonstrated apical hypokinesis by RNA in the RAO view. In the other 29 patients, a total of 58 resting segmental perfusion defects with abnormal wall thickening were present (12 anterior, 13 inferior, 14 apical, 11 septal and 8 posterolateral). Wall motion abnormalities were detected in all these patients and in 57/58 segments (98%) by biplane RNA. Septal and posterolateral wall motion abnormalities were detected in only the LAO RNA study. In three patients, wall motion abnormalities were detected by LAO imaging only. Of the remaining 87 normally perfused segments in these 29 patients, RNA wall motion was normal in 85. Two posterolateral segments demonstrated apparent hypokinesis, probably due to left atrial overlap in the LAO projection. CONCLUSION: Simultaneous biplane RNA accurately detects wall motion abnormalities frequently missed by single-plane RAO imaging.

Bone mineral content determined by functional imaging.

Quantitation of bone mineral by photon absorptiometry is a simple and accurate method for determining changes in bone volume and mineral content in serial studies. An extension of the scintillation camera method for studying such changes in the calcaneous is described. This technique is applicable to large areas of bone, thereby minimizing the effect of repositioning errors. Using a 40-mCi 241Am sheet source, a 2.1% reproducibility in bone phantoms and a 2.4% reproducibility in normal patients was achieved. Several case studies are presented to illustrate sensitivity and clinical application of the method. Although bone mineral determinations are now performed in a limited number of health care facilities, the scintillation camera method described in this report could increase the availability of these determinations significantly.

Automated patient report-generation in nuclear medicine.

The proliferation of computer-based office-management systems in the past few years has involved the private physician's office as well as the hospital laboratory. Many radiology departments have already adopted this approach for patient report generation and data storage. Due to the absence of commercially available software, some nuclear medicine departments will be interested in writing their own, but may not have enough experience in nonimaging computer applications to determine the performance needed for a practical system. A report-generation system for scintigraphic studies has been developed in our department over the past 2 yr. During this time an essential hardware/software performance level was established. Ideas for design of program flow that enhance staff acceptance of this concept are presented. Significant reduction of errors in report transcription and billing, together with reduced requirements for secretarial and clerical staff, make a general system like this cost effective.

Scintigraphic, electrocardiographic, and enzymatic diagnosis of perioperative myocardial infarction in patients undergoing myocardial revascularization.

To assess the incidence of perioperative myocardial infarction, 214 consecutive patients were evaluated 1-5 days after coronary bypass surgery, using Tc-99m pyrophosphate (TcPPi) myocardial imaging, serial electrocardiograms (ECG), and enzyme levels (SGOT, LDH, CPK). On the basis of the clinical course and scintigraphic, enzymatic, and ECG changes, the diagnosis of perioperative infarction was definite in 17 of 241 cases (7.9%) and probable in six of 241 (2.8%). In all of these 23 patients, TcPPi scans were abnormal; one additional patient had a false-positive scintigram. Only 13 of the 23 had ECG evidence of infarction, but there were no false positives. We set the threshold for abnormality of enzyme changes quite high, owing to experience in more than 900 postoperative patients (SGOT greater than 200, LDH greater than 500, CPK greater than 500 on the same day). Using these criteria, 22 of the 23 infarct patients had abnormal enzymes, and six others were falsely positive. These results indicate a relatively low sensitivity for the ECG in diagnosing perioperative infarction, but the lack of false positives suggests high specificity. The sensitivity and specificity of the enzymes and the TcPPi image were both excellent and quite similar; the main difference was a reduction of certainty of infarction with the enzyme criteria, caused by the six patients whose enzyme values were falsely positive. Considering its sensitivity, specificity, and ability to locate and to a certain extent quantitate necrosis. TcPPi imaging is probably the most valuable means of diagnosing perioperative myocardial infarction.

Image enhancement of severely hypoperfused myocardia for computation of tomographic ejection fraction.

UNLABELLED: Ejection fractions computed from 99mTc-sestamibi myocardial perfusion gated tomograms have demonstrated a high degree of accuracy and reproducibility. Although automated algorithms appear to provide reasonable endocardial outlines for patients over a broad spectrum of cardiac diseases, in cases of severe hypoperfusion, it is necessary to manually adjust contrast and brightness to judge whether borders are correct or must be altered. METHODS: Midventricular horizontal and vertical long axis gated tomograms were generated for 116 studies chosen on the basis of extensive, severe myocardial perfusion defects. Automated software transformed cinematic tomograms into images demonstrating uniform appearance of the myocardium throughout the cardiac cycle. Transformed images were introduced to edge detection algorithms for subsequent calculation of ventricular volumes and ejection fractions. RESULTS: Linear regression analysis demonstrated excellent intraobserver reproducibility for ejection fractions (r = 0.95) and volumes (r = 0.98). There was also good agreement of ejection fractions (r = 0.86) and volumes (r = 0.94) with values derived from an expert's manual drawings. In a subgroup of 22 patients, automated ejection fractions from transformed images demonstrated better agreement with independent first-pass values (r = 0.90) than did manual measurements derived from original data (r = 0.85). CONCLUSION: Image enhancement algorithms succeeded in providing accurate, reproducible gated SPECT ejection fractions in the most difficult class of patients exhibiting severe hypoperfusion.

First-pass ventricular ejection fraction using a single-crystal nuclear camera.

UNLABELLED: The purpose of the study was to evaluate the reliability of ejection fractions obtained from first-pass radionuclide ventriculography with a large field-of-view tomographic single-crystal gamma camera. METHODS: A SPECT camera had its electronics redesigned to improve counting efficiency and was equipped with an experimental ultra-high sensitivity collimator. Left ventricular ejection fraction (LVEF) was measured in 28 patients by 30 degrees RAO first-pass imaging and by "best septal view" LAO planar equilibrium radionuclide ventriculography on a conventional small field of view Anger camera. For 28 other patients, first-pass ejection fractions were compared to multicrystal gamma camera values. Visual analysis was performed to judge clinical acceptability of first-pass images for identification of wall-motion abnormalities. RESULTS: Linear regression analysis of first-pass against equilibrium ejection fraction demonstrated good correlation (r = 0.92; slope = 0.90; intercept = 3.8; s.e.e. = 6.4%). First-pass ejection fraction values also correlated linearly with multicrystal camera values for the left ventricle (r = 0.94; slope = 1.05; intercept = 1.3; s.e.e. = 5.3%). For a subgroup of 19 patients, single-crystal camera right ventricle ejection fraction demonstrated good correlation with multicrystal camera values (r = 0.82; slope = 1.15; intercept = 1.3; s.e.e. = 6.1%). Interobserver variability correlated as r = 0.99 for LVEF ejection fraction and r = 0.92 for RVEF. Chi-square analysis of single-crystal first-pass image visual scores versus those from the gated equilibrium acquisitions showed close agreement (p < 10(-8)). CONCLUSIONS: The evaluated camera/collimator system measured left and right ventricular ejection fraction accurately. Lung frame correction and dual regions were superior to paraventricular background correction and a fixed end-diastolic region.