Gated Myocardial Perfusion Single-photon Emission Computed Tomography Research Articles

Diastolic dyssynchrony assessment by gated myocardial perfusion-SPECT in subjects who underwent cardiac resynchronization therapy

BackgroundLeft ventricular diastolic dyssynchrony (LVDD) can be assessed by gated myocardial perfusion single-photon emission computed tomography (GMP-SPECT). LVDD is an area of interest in subjects who underwent cardiac resynchronization therapy (CRT). The aim of this post hoc analysis was to assess the role of LVDD in subjects with CRT who were followed up at 6-month period. Material & MethodsLeft ventricular diastolic dyssynchrony was assessed by GMP-SPECT at baseline and after CRT procedure in 160 subjects from 10 different cardiological centers. CRT procedure was performed as per current guidelines. Outcomes were defined as improvement in ≥1 New York Heart Association (NYHA) class, left ventricular ejection fraction (LVEF) by 5%, and reduction in end-systolic volume (ESV) by 15% and 5% points in Minnesota Living with Heart Failure Questionnaire. LVDD was defined as diastolic phase standard deviation ≥40 ± 14°. ResultsImprovement in NYHA functional class occurred in 105 (65.6%), LVEF in 74 (46.3%), decrease in ESV in 86 (53.8%), and Minnesota score in 85 (53.1%) cases. Baseline LV diastolic standard deviation was 53.53° ± 20.85 and at follow-up 40.44° ± 26.1283; (P < 0.001). LVDD was not associated with improvement in clinical outcomes at follow-up. ConclusionCRT improves both systolic and diastolic dyssynchrony values at 6-month follow-up. LVDD at baseline is correlated with cardiac functionality at follow-up, but not with overall favorable clinical outcomes.

Assessment of Left Ventricular Diastolic Function Using ECG-gated Myocardial Perfusion SPECT in Small Heart: Comparison with Ultrasound Echocardiography

Assessment of left ventricular (LV) diastolic function is important because it is possible to detect early sign of myocardial ischemia by this assessment. The purpose of this study was to compare between electrocardiogram (ECG) -gated myocardial perfusion single photon emission computed tomography (G-SPECT) and ultrasound echocardiography in assessment of LV diastolic function in the small heart (SH). The study population consisted of 144 patients who underwent both G-SPECT and ultrasound echocardiography. Peak filling rate (PFR), one-third mean filling rate (1/3 MFR) and the ratio of time to PFR to the RR interval (TPFR/RR) were calculated by quantitative gated SPECT (QGS) and heart risk view-F (HRV-F). Peak early mitral annular velocity (e') was used as the reference standard of LV diastolic function. There were 33 patients with end-systolic volume (ESV) of ≤10 ml (SH10), 51 patients with ESV of 11-20 ml (SH 20) and 60 patients with ESV of >20 ml (normal-sized heart: NH). In SH10, PFR calculated by QGS was not correlated with e'. However, that by HRV-F was significantly correlated with e' (r=0.47, p=0.006). On the other hand, 1/3 MFR and TPFR/RR calculated by QGS and HRV-F were not correlated with e' in SH10 and SH20. PFR, 1/3 MFR and TPFR/RR calculated by QGS and HRV-F were correlated with e' in NH.

The assessment of septal wall motion in patients undergoing CABG by myocardial perfusion-gated SPECT

In this study, we aimed to assess the presence and prevalence of paradoxical septal motion (PSM) by myocardial perfusion-gated single-photon emission computed tomography (SPECT) imaging in patients undergoing coronary artery bypass grafting (CABG). A total of 172 patients (145 men and 27 women, with a mean age of 64.81 ± 8.93 years) undergoing CABG surgery were included in the study. All selected scintigraphic studies of the patients undergoing CABG were reprocessed. Semiquantitative interpretation of septal perfusion, wall motion, and wall thickening was performed with QPS and QGS programs. Phase analysis parameters were also obtained using the Emory Cardiac Toolbox. According to myocardial perfusion-gated SPECT results, the patients were trichotomized as follows: group 1 (nonischemic PSM): regular perfusion and thickening of the septal wall and abnormal motion of the septal wall; group 2 (ischemic PSM): abnormal perfusion, motion, and thickening of the septal wall; group 3 (non-PSM): normal perfusion, motion, and thickening of the septal wall. The data in each of the three groups were compared using Student's t-test and one-way analysis of variance. No PSM (normal perfusion, motion, and thickening of the septal wall) was observed in 19.2% of patients undergoing CABG, whereas nonischemic PSM (regular perfusion and thickening of the septal wall and abnormal motion of the septal wall) was observed in 60.5% of patients and ischemic PSM (abnormal perfusion, motion and thickening of the septal wall) was seen in 20.3% of patients. According to our study results, PSM is fairly common in patients undergoing CABG. It will be beneficial to use myocardial perfusion scintigraphy-gated SPECT, which is a noninvasive examination method, to identify the presence of PSM and investigate whether it is accompanied by ischemia or infarction.

Stress-induced myocardial ischemia modifies phase analysis indices obtained from Tc-99m sestamibi gated single photon emission computed tomography myocardial perfusion imaging

Purpose: Phase analysis of gated myocardial perfusion single photon emission computed tomography (GSPECT) images allows the assessment of left ventricle (LV) mechanical synchrony. The aim of our study was to determine whether stress-induced ischemia modifies the two most commonly used phase analysis synchrony parameters: Histogram bandwidth (HB) and Standard deviation (SD) obtained from Tc 99m sestamibi of GSPECT images and to evaluate the correlation between these indices and different amounts of ischemia. Methods: We included 92 consecutive ischemic patients defined by SDS≥2 who underwent a two-day stress-rest protocol Tc99 sestamibi GSPECT between August 2011 and July 2012 and we compared them to a group of 22 normal subjects defined as asymptomatic, without known coronary artery disease, with low pretest of coronary artery disease, and normal ECG, stress test, left ventricular function and perfusion (SSS: 0), who followed the same GSPECT protocol. Patients with left bundle branch block, ventricular pacing and fixed perfusion defects were excluded. Phase analysis indices HB and SD were obtained from stress and rest images in both groups. We obtained the change (stress minus rest) of SD and HB indices for each patient. The ischemic group was divided into moderate-to-severe ischemia (SDS≥5), and severe ischemia (SDS≥8). Results: The ischemic group had a mean age of 63±10 years, 47 were men, 21 had moderate-to-severe ischemia and 10 severe ischemia. Ischemic patients showed higher stress SD and HB values than normal subjects (SD 15.65 vs 11.76, p=0.0002 and HB 47.74 vs 38.04, p=0.002 respectively) and larger amounts of ischemia showed higher values: moderate to severe ischemia (SD 20.08 vs 11.76, p<0.001 and HB 59.61 vs 38.04 p=0.001 respectively) and severe ischemia (SD 19 vs 11.76, p<0.0001 and HB 60.4 vs 38, p<0.0001 respectively). Changes in SD and HB were significatively higher in ischemic patients than in normal subjects (SD -0.19 vs -0.58, p<0.0001; HB 1.27 vs -0.95, p=0.0002 respectively). These differences were even higher in moderate to severe ischemia (SD 2.49 vs -0.58, p=0,0002; HB 4.76 vs -0.95, p<0.0001) and severe ischemia (SD 2.42 vs -0.58, p=0,0001; HB 12.5 vs -0.95, p<0.0001). Conclusion: In our population left ventricular mechanical synchrony indices obtained by phase analysis of Tc99sestamibi GSPECT imaging, HD and SD are altered in the presence of myocardial ischemia. Larger amounts of ischemia are related to higher dyssynchrony values of the phase-derived indices HB and SD.

Long-Term Follow-up Assessment After the Arterial Switch Operation for Correction of Dextro-Transposition of the Great Arteries by Means of Exercise Myocardial Perfusion-Gated SPECT

The arterial switch operation (ASO) is the preferred technique for correcting transposition of the great arteries, but translocation and reimplantation of the coronary arteries can produce myocardial ischemia. This report aims to describe the authors' experience with exercise single-photon emission computed tomography (SPECT) used to evaluate myocardial perfusion. Exercise-rest gated-myocardial perfusion SPECT was performed for 69 patients (49 boys; median age, 9years; 5th percentile [6.4years] to 95th percentile [15.6years]), 64 of whom were asymptomatic 9.98±3.20years after ASO. During exercise testing, the patients reached 9.85±3.05 metabolic equivalents (METs) and a median heart rate of 160beats per minute (bpm), 5th percentile (106bpm) to 95th percentile (196bpm). Whereas 61 patients (88.41%) had normal myocardial perfusion, 2 patients (2.9%) had reversible defects, and 6 patients (8.7%) had fixed defects. All the patients with perioperative ischemic complications (4/4, 100%) had myocardial perfusion defects, whereas four patients (4/65, 6.15%) without ischemic complications had abnormal perfusion (p=0.0005). Age at the time of surgery did not differ significantly (p=0.234) between the patients with perfusion defects and those with normal study results. No significant difference was observed between the patients who had an A coronary pattern (left coronary artery originating from the left sinus and the right coronary artery originating from the right sinus, n=47) and those who had a non-A coronary pattern (n=22) (p=1). The high rate for normality of exercise myocardial perfusion in our study suggests that myocardial perfusion gated-SPECT should be reserved for patients who have experienced perioperative ischemic complications or those with symptoms, at least during the first 10years after the surgery.

Risk stratification and prognostic assessment by myocardial perfusion-gated SPECT in patients with left bundle-branch block and low-intermediate cardiac risk

In high-risk patients with left bundle-branch block (LBBB), functional but not perfusion parameters yield incremental prognostic information. The aim of our study was to evaluate the prognostic value of gated single photon emission computed tomography (SPECT) in low-intermediate risk LBBB patients. One hundred seventy-six subjects underwent stress-rest dual-day protocol 99mTc sestamibi-gated SPECT and were dichotomized in two groups: without LBBB (Group 1, n = 86) and with LBBB (Group 2, n = 90). Patients were followed for 32 ± 18 months. Cox regression multivariate analysis was used to determine which variable was the best predictor of cardiac event. Event-free survival curves were computed by Kaplan-Meier method. Myocardial perfusion scintigraphy was abnormal in 32 and 60 patients for Groups 1 and 2, respectively (37 vs. 67 %, p < 0.001). In Groups 1 and 2, the mean summed stress score (SSS) was 3.7 ± 5.6 versus 6.7 ± 6.4, while the mean summed difference score (SDS) was 1.6 ± 2.5 versus 2.7 ± 3.3 (both p < 0.005); therefore 34 % of patients in Group 1 and 53 % of those in Group 2 presented myocardial ischemia. All functional parameters were significantly different between the two subsets (all p < 0.005). Follow-up was completed in 161 patients (92 %); 10 events occurred in Group 1 and 20 in Group 2 (14 vs. 25 %). The event-free survival was significantly higher in patients with normal than in those with abnormal scan (85 vs. 63 %, p < 0.005); moreover, the prognosis of patients with LBBB was significantly worse. At multivariate analysis, SDS was found to be the only independent predictor of cardiac events both in all patients and in LBBB population (HR 3.08, and HR 4.99, p < 0.05). This is the first study to assess the prognostic value of gated SPECT in patients with LBBB and low-intermediate cardiac risk. Both perfusion and functional data obtained by gated SPECT are different between patients with and without LBBB. However, SDS is the only predictor of events. Thus, the amount of reversible ischemia at gated SPECT has a discriminative power in stratifying the cardiac risk of LBBB population.

Impact of image reconstruction on phase analysis of ECG-gated myocardial perfusion SPECT studies

Phase analysis (SyncTool) has been developed to assess left-ventricular (LV) dyssynchrony from gated myocardial perfusion single-photon emission computed tomography (GSPECT) studies. Conventionally, GSPECT data are reconstructed using filtered backprojection (FBP). This study is intended to determine the impact of various iterative reconstruction methods on SyncTool. Thirty consecutive patients, acquired using a Philips CardioMD system, were enrolled in this study. The GSPECT data were reconstructed using FBP, maximum likelihood expectation maximization (MLEM), MLEM with three-dimensional resolution recovery (Astonish), MLEM with Vantage attenuation correction (AC), and MLEM with Vantage AC and three-dimensional Monte Carlo-based scatter correction (ACSC), respectively. The reconstructed data were then submitted to SyncTool to measure LV dyssynchrony (phase standard deviation and histogram bandwidth). The paired t-test was used to compare the LV dyssynchrony indices given by MLEM, Astonish, AC, and ACSC, respectively, with those given by the FBP. No statistical significance was observed for any comparison between iterative reconstruction methods and the FBP. Reconstruction methods have insignificant impact on the LV dyssynchrony indices, indicating that the standard FBP reconstruction is sufficient for accurate phase analysis, supporting the widespread clinical use of SyncTool in measuring LV dyssynchrony.

Temporal resolution of multiharmonic phase analysis of ECG-gated myocardial perfusion SPECT studies

Multiharmonic phase analysis (MHPA) was developed to assess left-ventricular dyssynchrony from gated myocardial perfusion single-photon emission computed tomography (GSPECT) studies. This study was intended to determine the temporal resolution of MHPA. A reference normal GSPECT study with 128 frames/cycle was simulated using NCAT, a nonuniform rational B-splines-based cardiac torso phantom. It was shifted in the time domain to insert phase delays. Realistic GSPECT studies (8 or 16 frames/cycle) were then obtained by down-sampling the reference and shifted studies. All GSPECT projections were generated with attenuation, scatter, collimator blurring, and Poisson noise. Seventeen regional phases were calculated from the GSPECT reconstructions (filtered back-projection without compensation for physical factors), using linear interpolation for the reference study, and MHPA for the realistic studies. Comparing the regional phases between the realistic studies without and with shifts determined whether MHPA could identify certain phase delays. When there were enough counts/pixel (>10 counts/pixel), MHPA with either 1, 2, or 3 harmonics could resolve a phase difference of 5.6 degrees , corresponding to 1/64 of the cardiac cycle. With clinically equivalent counts, the temporal resolution of MHPA is 1/64 of a cardiac cycle. Achieving this high temporal resolution from data with low temporal resolution demonstrates the benefit of replacing discrete points with continuous harmonic functions.

Respiratory Motion Detection and Correction in ECG-Gated SPECT: a New Approach

ObjectiveGated myocardial perfusion single-photon emission computed tomography (GSPECT) has been established as an accurate and reproducible diagnostic and prognostic technique for the assessment of myocardial perfusion and function. Respiratory motion is among the major factors that may affect the quality of myocardial perfusion imaging (MPI) and consequently the accuracy of the examination. In this study, we have proposed a new approach for the tracking of respiratory motion and the correction of unwanted respiratory motion by the use of respiratory-cardiac gated-SPECT (RC-GSPECT). In addition, we have evaluated the use of RC-GSPECT for quantitative and visual assessment of myocardial perfusion and function.Materials and MethodsTwenty-six patients with known or suspected coronary artery disease (CAD)-underwent two-day stress and rest 99mTc-Tetrofosmin myocardial scintigraphy using both conventional GSPECT and RC-GSPECT methods. The respiratory signals were induced by use of a CT real-time position management (RPM) respiratory gating interface. A PIO-D144 card, which is transistor-transistor logic (TTL) compatible, was used as the input interface for simultaneous detection of both ECG and respiration signals.ResultsA total of 26 patients with known or suspected CAD were examined in this study. Stress and rest myocardial respiratory motion in the vertical direction was 8.8-16.6 mm (mean, 12.4 ± 2.9 mm) and 7.8-11.8 mm (mean, 9.5 ± 1.6 mm), respectively. The percentages of tracer intensity in the inferior, inferoseptal and septal walls as well as the inferior to lateral (I/L) uptake ratio was significantly higher with the use of RC-GSPECT as compared to the use of GSPECT (p < 0.01). In a left ventricular ejection fraction (LVEF) correlation analysis between the use of rest GSPECT and RC-GSPECT with echocardiography, better correlation was noted between RC-GSPECT and echocardiography as compared with the use of GSPECT (y = 0.9654x + 1.6514; r = 0.93, p < 0.001 versus y = 0.8046x + 5.1704; r = 0.89, p < 0.001). Nineteen (19/26) patients (73.1%) showed abnormal myocardial perfusion scans with reversible regional myocardial defects; of the 19 patients, 14 (14/26) patients underwent coronary angiography.ConclusionRespiratory induced motion can be successfully corrected simultaneously with the use of ECG-gated SPECT in MPI studies using this proposed technique. Moreover, the use of ECG-gated SPECT improved image quality, especially in the inferior and septal regions that are mostly affected by diaphragmatic attenuation. However, the effect of respiratory correction depends mainly on the patient respiratory pattern and may be clinically relevant in certain cases.

Impact of Operator on Determining Functional Parameters of Nuclear Medicine Procedures

Objective: The study was designed to assess the significance of the interoperator variability in theestimation of functional parameters forfour nuclear medicine procedures. Materials andMethods: Three nuclear medicine technologists with varying years of experience processed the following randomly selected 20 cases with diverse functions of each study type: renography, renal cortical scans, myocardial perfusion gated single-photon emission computed tomography (MP-GSPECT) and gated blood pool ventriculography (GBPV). The technologists used the same standard processing routines and were blinded to the results of each other. The means of the values and the means of differences calculated case by case were statistically analyzed by one-way ANOVA. The values were further analyzed using Pearson correlation. Results: The range of the mean values and standard deviation of relative renal function obtained by the three technologists were 50.65 ± 3.9 to 50.92 ± 4.4% for renography, 51.43 ± 8.4 to 51.55 ± 8.8% for renal cortical scans, 57.40 ± 14.3 to 58.30 ± 14.9% for left ventricular ejection fraction from MP-GSPECT and 54.80 ± 12.8 to 55.10 ± 13.1% for GBPV. The difference was not statistically significant, p > 0.9. The values showed a high correlation of more than 0.95. Calculated case by case, the mean of differences ± SD was found to range from 0.42 ± 0.36% in renal cortical scans to 1.35 ± 0.87% in MP-GSPECT with a maximum difference of 4.00%. The difference was not statistically significant, p >0.19. Conclusion: The estimated functional parameters were repro ducible and operator independent as long as the standard processing instructions were followed.