Stress/rest myocardial perfusion scintigraphy in patients without significant coronary artery disease.

AIM: To define the prognostic impact of stress myocardial perfusion scintigraphy (MPS) in patients with angiographic exclusion of significant coronary artery disease. METHODS: Angiographic and MPS databases were matched to define patients without significant coronary artery disease by quantitative angiography (diameter stenosis <50%) who underwent stress MPS and coronary angiography within a time period of 3 months. A total of 118 patients were identified and followed for a mean of 6.3 +/- 1.2 years for death, a composite of death, myocardial infarction, bypass surgery, or percutaneous coronary intervention [MAE]) as well as occurrence of symptoms (angina or dyspnoe class CCS II to IV). Stress and rest MPS (using (99m)Tc-MIBI or tetrofosmin) were analyzed by quantitative perfusion SPECT (QPS) for summed stress and rest scores (SSS/SRS). RESULTS: There were 16 deaths, 29 MAE, and 76 patients with MAE or significant symptoms during follow-up. Significant differences in SSS were found between patients who died (9.5 +/- 6.9 vs. 5.4 +/- 5.6, P = 0.012), had MAE (8.7 +/- 7.2 vs. 5.2 +/- 5.0, P = 0.010), or had MAE or significant clinical symptoms (7.2 +/- 7.1 vs. 4.6 +/- 6.2, P = 0.042) compared to those without the respective event. Logistic regression analysis demonstrated SSS to be a predictor of death (OR = 1.074 [95% CI: 1.004-1.149], P = 0.026) and MAE (OR = 1.087 [95% CI: 1.004-1.181], P = 0.027). CONCLUSIONS: In patients without significant angiographic coronary artery disease, the result of stress MPS is a predictor of long-term prognosis. Quantitative analysis of MPS allows definition of patients with a higher likelihood to develop clinical events or symptoms.

Gated myocardial perfusion SPECT: algorithm-specific influence of reorientation on calculation of left ventricular volumes and ejection fraction.

UNLABELLED: Gated myocardial perfusion SPECT allows calculation of end-diastolic and end-systolic volumes (EDV and ESV, respectively) and left ventricular ejection fraction (LVEF). The quantification algorithms QGS (quantitative gated SPECT), 4D-MSPECT, and CARE heart show a good correlation with cardiac MRI. Nevertheless, differences in contour finding suggest algorithm-specific effects if heart axes vary. The effect of tilting heart axes on gated SPECT was quantified as a possible source of error. METHODS: Sixty men underwent gated SPECT (450 MBq of (99m)Tc-tetrofosmin or sestamibi, 8 gates/cycle). After correct reorientation (R(0)), datasets were tilted by 5 degrees , 10 degrees , 15 degrees , 20 degrees , 30 degrees , and 45 degrees along both long axes (R(5), R(10), R(15), R(20), R(30), and R(45), respectively). EDV, ESV, and LVEF were calculated using QGS, 4D-MSPECT, and CARE heart. Because a 15 degrees tilt could be a maximum possible misreorientation in routine, R(0) and R(15) results were analyzed in detail. Absolute-difference values between results of tilted and correctly reoriented datasets were calculated for all tilts and algorithms. RESULTS: QGS and CARE heart succeeded for R(0) and R(15) in all cases, whereas 4D-MSPECT failed to find the basal plane in 1 case (patient B). R(2) values between paired R(15)/R(0) results were 0.992 (QGS), 0.796 (4D-MSPECT; R(2) = 0.919 in n = 59 after exclusion of the failed case), and 0.916 (CARE heart) for EDV; 0.994 (QGS), 0.852 (4D-MSPECT; R(2) = 0.906 in n = 59), and 0.899 (CARE heart) for ESV; and 0.988 (QGS), 0.814 (4D-MSPECT; R(2) = 0.810 in n = 59), and 0.746 (CARE heart) for LVEF. Concerning all levels of misreorientation, 1 patient was excluded for all algorithms because of multiple problems in contour finding; additionally for 4D-MSPECT patient B was excluded. In the 45 degrees group, QGS succeeded in 58 of 59 cases, 4D-MSPECT in 58 of 58, and CARE heart in 33 of 59. Mean absolute differences for EDV ranged from 5.1 +/- 4.1 to 12.8 +/- 10.5 mL for QGS, from 6.7 +/- 6.3 to 34.2 +/- 20.7 mL for 4D-MSPECT, and from 5.4 +/- 5.6 to 25.2 +/- 16.1 mL for CARE heart (tilts between 5 degrees and 45 degrees ). Mean absolute differences for ESV ranged from 4.1 +/- 3.7 to 8.0 +/- 9.4 mL for QGS, from 5.6 +/- 8.0 to 10.0 +/- 10.5 mL for 4D-MSPECT, and from 5.4 +/- 5.6 to 25.5 +/- 16.1 mL for CARE heart. Mean absolute differences for LVEF ranged from 1.1% +/- 1.0% to 2.2% +/- 1.8% for QGS, from 4.0% +/- 3.5% to 8.0% +/- 7.1% for 4D-MSPECT, and from 3.4% +/- 2.9% to 9.2% +/- 6.0% for CARE heart. CONCLUSION: Despite tilted heart axes, QGS showed stable results even when using tilts up to 45 degrees . 4D-MSPECT and CARE heart results varied with reorientation of the heart axis, implying that published validation results apply to correctly reoriented data only.

Volume/perfusion ratio from lung SPECT/CT.

AIM: In pulmonary emphysema lung volume reduction procedures (LVRP) can optimize respiratory pump function. Identification of the most affected lobe can be reached using relative lobar volume (relVol) from CT, but this approach disregards the corresponding lobar perfusion. The aim of the study was therefore to establish a new parameter combining relVol from CT and relative perfusion (relPerf) from perfusion SPECT as a single parameter (volume/perfusion ratio (VPR)) to optimize the identification procedure. METHODS: As a proof of principle VPR was calculated from hybrid V-/P-SPECT/CT scans from 20 patients with severe pulmonary emphysema (SPE) before LVRP. Lung V-/P-SPECT/CT (Siemens SymbiaT) was done with Technegas and 99mTc-MAA. Quantification of lobar perfusion from scintigraphy and volume from CT was performed using "HERMES Hybrid 3D - Lung Lobe Quantification". Using normal ranges - from 12 patients with suspected pulmonary embolism and normal lung structure and perfusion - all lobes were classified as normal or abnormal to identify targets for LVRP. RESULTS: Normal values for VPR: right upper lobe 1.09 ± 0.10, middle lobe 1.31 ± 0.31, right lower lobe 0.87 ± 0.08; left upper lobe 1.09 ± 0.11, left lower lobe 0.87 ± 0.12. In the 20 SPE patients there were only 7 lobes with pathological values for rel- Vol, 14 lobes with pathological values for rel- Perf but 31 lobes with pathological VPR. CONCLUSION: Estimation of VPR from lung SPECT/CT enables a combined view of lobar volume and perfusion with one parameter. In SPE patients VPR allows identifying possible target structures with much higher sensitivity than when using relPerf or relVol alone. The specificity and the prognostic value of this new parameter have to be tested in a clinical trial.

Quantitative myocardial perfusion-SPECT: algorithm-specific influence of reorientation on calculation of summed stress score.

PURPOSE: Myocardial perfusion SPECT (MPS) with software-assisted determination of summed stress score (SSS) is of established importance for diagnosis/therapy planning in coronary artery disease. Differences in contour finding suggest algorithm-specific influence on quantification if heart axes are chosen incorrectly. Thus, this study quantified the influence of heart-axis tilt on SSS calculation using Quantitative Perfusion SPECT and 4D-MSPECT. PATIENTS AND METHODS: Stress MPS of 50 men acquired on a triple-head gamma camera were correctly reoriented by experienced technologists (R0) and then tilted by 5 degrees/10 degrees/15 degrees/20 degrees/30 degrees/45 degrees along both long axes (R5-R45). SPECT images were quantified for SSS using QPS and 4D-MSPECT. SSS values for R0 and R5-R45 were analyzed using correlation analysis. Weighted kappa values (κ) were calculated to measure agreement regarding perfusion abnormality severity (4-step SSS rating: 0-3, 4-8, 9-13, and ≥14). RESULTS: For QPS SSS correlation, R0 vs. tilted datasets remained very high (R > 0.97) up to 20 degrees, but degraded for higher tilts (R = 0.895/0.780 for 30 degrees/45 degrees). 4D-MSPECT showed comparable SSS correlation only up to 10 degrees (R > 0.95) and strong deterioration thereafter (R = 0.863-0.347 for 15-45 degrees). Deviation in severity class from R0 increased from 6/50 (R5; κ = 0.914) to 25/50 (R45; κ = 0.252) using QPS and from 7/50 (R5; κ = 0.899) to 33/50 (R45; κ = 0.065) using 4D-MSPECT. CONCLUSION: For tilted MPS datasets, considerable differences in SSS calculation emerge using QPS and 4D-MSPECT. QPS showed more stable results than 4D-MSPECT.

Results of interventional treatment of stress positive coronary artery disease.

The aim of this study was to define the impact of percutaneous coronary intervention (PCI) including stenting in patients with stress-positive stable coronary artery disease on long-term prognosis and symptoms. A group of 1,018 patients were identified from the angiographic and single-photon emission computed tomographic (SPECT) databases (technetium-99m sestamibi or tetrofosmin at rest and during stress) January 1, 2000, to December 31, 2003, to have significant coronary artery disease (>50% diameter stenosis on quantitative coronary angiography) and positive SPECT findings. Two hundred sixty-six patients were medically treated. Seven hundred fifty-two patients with positive SPECT findings who underwent PCI were matched to 266 patients of similar age, gender, number and location of stenotic arteries, left ventricular function, and size of SPECT perfusion defect who underwent medical treatment. Clinical events (death, nonfatal myocardial infarction, and revascularization) as well as clinical symptoms (angina or dyspnea, Canadian Cardiovascular Society class II to IV) were determined after a follow-up period of 6.4 +/- 1.2 years. In 524 of the 532 patients (98%), clinical follow-up was obtained. There were no differences between the PCI and medical groups in the frequencies of death (13.5% vs 10.9%) and myocardial infarction (5.3% vs 5.6%) during follow-up. PCI patients had more revascularization procedures <1 year after choice of treatment modality (14.7% vs 6.0%, p <0.002). During the subsequent follow-up period (>1 year), the 2 groups did not differ in the frequency of revascularization procedures. At the end of follow-up, patients in the PCI group complained less frequently of angina pectoris (38% vs 49%, p = 0.014). In conclusion, in patients with stress-positive stable coronary artery disease, PCI including stenting did not reduce mortality or rate of nonfatal myocardial infarction. The PCI group complained less frequently of angina pectoris at long-term follow-up.

Quantification of left ventricular volumes and ejection fraction from gated 99mTc-MIBI SPECT: MRI validation of the EXINI heart software package.

UNLABELLED: The aim of the study was to validate the accuracy of the EXINI heart software (EXINI) package in assessing left ventricular end-diastolic/systolic volumes (EDV, ESV) and ejection fraction (LVEF) from gated (99m)Tc-MIBI single-photon emission tomography (SPECT). Cardiac magnetic resonance imaging (cMRI) was used as reference. Furthermore, effects of perfusion defects and image quality in SPECT on correlation between gated SPECT and magnetic resonance imaging were investigated. METHODS: Seventy patients were examined using gated SPECT (rest study, eight gates per cardiac cycle). EDV, ESV and LVEF were calculated from gated SPECT using EXINI. Directly before or after SPECT, cMRI (20 gates cardiac per cycle) was performed. EDV, ESV and LVEF were calculated using Simpson's rule. Perfusion defects were quantified using the summed-rest-score (SRS). Total number of myocardial counts were used to rate image quality. RESULTS: Correlation between results of gated SPECT and cMRI was high for EDV (R = 0.89) and ESV (R = 0.94) and good for LVEF (R = 0.78). ESV (EXINI 54 +/- 31 ml versus cMRI 57 +/- 34 ml) and LVEF (EXINI 62.9 +/- 11.7% versus cMRI 60.6 +/- 13.9%) did not differ significantly whereas EXINI overestimated EDV significantly compared with cMRI (EXINI 144 +/- 41 ml versus cMRI 137 +/- 36 ml; P<0.005). No correlation was found between absolute differences of the results given by gated SPECT and cMRI and SRS or total myocardial counts (R < 0.18). CONCLUSION: End-diastolic volume, ESV and LVEF calculated from gated SPECT using EXINI agree with cMRI over a wide range of values. Correlation between both the methods was good for EDV and ESV, and acceptable for LVEF. No relevant influence of image quality or SRS on the accuracy of EXINI results was found.

Comparison of SSS and SRS calculated from normal databases provided by QPS and 4D-MSPECT manufacturers and from identical institutional normals.

PURPOSE: There is proven evidence for the importance of myocardial perfusion-single-photon emission computed tomography (SPECT) with computerised determination of summed stress and rest scores (SSS/SRS) for the diagnosis of coronary artery disease (CAD). SSS and SRS can thereby be calculated semi-quantitatively using a 20-segment model by comparing tracer-uptake with values from normal databases (NDB). Four severity-degrees for SSS and SRS are normally used: <4, 4-8, 9-13, and > or =14. Manufacturers' NDBs (M-NDBs) often do not fit the institutional (I) settings. Therefore, this study compared SSS and SRS obtained with the algorithms Quantitative Perfusion SPECT (QPS) and 4D-MSPECT using M-NDB and I-NDB. METHODS: I-NDBs were obtained using QPS and 4D-MSPECT from exercise stress data (450 MBq (99m)Tc-tetrofosmin, triple-head-camera, 30 s/view, 20 views/head) from 36 men with a low post-stress test CAD probability and visually normal SPECT findings. Patient group was 60 men showing the entire CAD-spectrum referred for routine perfusion-SPECT. Stress/rest results of automatic quantification of the 60 patients were compared to M-NDB and I-NDB. After reclassifying SSS/SRS into the four severity degrees, kappa values were calculated to objectify agreement. RESULTS: Mean values (vs M-NDB) were 9.4 +/- 10.3 (SSS) and 5.8 +/- 9.7 (SRS) for QPS and 8.2 +/- 8.7 (SSS) and 6.2 +/- 7.8 (SRS) for 4D-MSPECT. Thirty seven of sixty SSS classifications (kappa = 0.462) and 40/60 SRS classifications (kappa = 0.457) agreed. Compared to I-NDB, mean values were 10.2 +/- 11.6 (SSS) and 6.5 +/- 10.4 (SRS) for QPS and 9.2 +/- 9.3 (SSS) and 7.2 +/- 8.6 (SRS) for 4D-MSPECT. Forty four of sixty patients agreed in SSS and SRS (kappa = 0.621 resp. 0.58). CONCLUSION: Considerable differences between SSS/SRS obtained with QPS and 4D-MSPECT were found when using M-NDB. Even using identical patients and identical I-NDB, the algorithms still gave substantial different results.