Myocardial Perfusion Single Photon Emission Computed Tomography Studies Research Articles

Diagnostic Value of Single-Photon Emission Tomography Stress Test in Patients With Suspected Coronary Artery Disease in Saudi Arabia.

BackgroundInvasive coronary angiography (ICA) is the gold standard procedure for the diagnosis of coronary artery disease (CAD). ICA allows for clear visualization of the coronary arterial blood flow. Single-photon emission computed tomography (SPECT) is currently in widespread use to non-invasively evaluate patients known or suspected of coronary artery disease (CAD). This study aimed to examine the association between (SPECT) stress test and elective ICA in terms of diagnostic value in patients suspected of coronary artery disease at the King Faisal Cardiac Center (KFCC), Jeddah, Saudi Arabia.MethodsThis study is a retrospective diagnostic validation study using a consecutive sampling technique to select the study sample at KFCC. The study included all patients who presented with chest pain that were investigated with either exercise or pharmacologic myocardial perfusion SPECT study followed by elective ICA within six months from January 2015 to January 2020.ResultsA total of 207 patients met the inclusion criteria, where 43% (n = 90) of patients were females and 57% (n = 117) were males; 68% (n = 141) of the patients had both test results concordant (both SPECT and ICA results were in agreement). In 32% of the patients (n = 66), there was a discordant result (discrepant result between SPECT and ICA). SPECT had a sensitivity of 92.4% and a specificity of 26.3%. SPECT had a negative predictive value of 0.68 and a positive predictive value of 0.66 compared to ICA. There was a low degree of reliability between SPECT and ICA.ConclusionReliability between the SPECT and ICA in exclusion of significant CAD is high. The rate of false-positive tests was high while the accuracy of SPECT in detecting CAD in patients with diabetes and hypertension was high. The overall reliability of SPECT to ICA in the Saudi population was low.

Myocardial flow reserve derived by dynamic perfusion single-photon emission computed tomography reflects the severity of coronary atherosclerosis.

A novel single-photon emission computed tomography (SPECT) camera was developed to evaluate dynamic myocardial perfusion flow. However, it is unclear whether myocardial flow reserve (MFR) derived by dynamic perfusion SPECT using the novel SPECT camera (D-SPECT) reflects the severity of coronary atherosclerosis. In the present study, we therefore examined the relationship between MFR using D-SPECT and severity of coronary lesions. The study population comprised 40 patients who underwent both a myocardial dynamic perfusion SPECT study and invasive coronary angiography. The severity of coronary atherosclerosis was evaluated using the Gensini score. All patients underwent a rest/stress SPECT imaging protocol using Tc-99m-sestamibi, and dynamic acquisition was performed. Stress and rest flow was evaluated, and the global and regional MFR was calculated. Global MFR showed a significant negative correlation with Gensini score (r = - 0.345, p = 0.037). Multiple linear regression analysis showed that only global MFR was independently related to Gensini score (p = 0.018). Regional MFR was significantly lower in regions with 90% ≤ stenotic lesions compared with regions with < 90% stenotic lesions (p = 0.009). Global MFR derived by dynamic perfusion SPECT using D-SPECT reflects the severity of coronary atherosclerosis. Further, regional MFR is modulated by severe coronary artery stenotic lesions.

心筋SPECT 検査での多焦点ファンビームコリメータにおける画像再構成条件の最適化

The aim of this study was to optimize the reconstruction parameters for ordered subset conjugate gradient minimization (OSCGM) reconstruction using a multifocus fan beam collimator in myocardial perfusion single photon emission computed tomography (SPECT). We attempted to validate the following performance of OSCGM reconstruction parameters (iteration and subset). SPECT images were acquired using a dual-head gamma camera with IQ mode acquisition systems from a RH-2 cardiac phantom containing a 99m-Tc solution. The performance was evaluated using reconstruction parameters (product of subset and iteration: SI) with image contrast, LV volume [using quantitative perfusion SPECT (QPS)], root mean square uncertainty (RMSU), and normalized mean squared error (NMSE). The best results (contrast, uniformity, LV volume, and NMSE) were found for SI: 30. LV volume indicated the true volume for subset: 1 and iteration: 30, and LV volume was underestimated by 10% for iteration >20, and subset >1. The results of this myocardial perfusion SPECT study suggest the optimal OSCGM reconstruction parameter to be subset: 1 and iteration: 30 using a multifocus fan beam collimator.

A simple method for calculating the trade-off between noise / sampling error and interval number in gated SPECT.

The introduction of cardiac gating to the myocardial perfusion SPECT (single photon emission computed tomography) study affords the ability to simultaneously assess both myocardial perfusion and function (1). The ease of its application for image acquisition, processing and display and automatic quantitation capabilities assured its rapid and widespread clinical implementation. While gating myocardial perfusion SPECT offers physical and clinical advantages that are well recognised, the improved temporal resolution over non gated SPECT may come at the expense of a deteriorating signal to noise ratio (SNR) (2). That is, gated SPECT results in lower count density per individual frame compared to the same SPECT acquisition without gating by a factor equal to the number of gate intervals. Not only does a poor SNR have an adverse effect on image quality but the lower count statistics also result in greater statistical uncertainty for data entering mathematical reconstruction.

Unusual Extracardiac Findings Detected on Myocardial Perfusion Single Photon Emission Computed Tomography Studies With Tc-99m Sestamibi

The authors describe the incidence and various uptake patterns of Tc-99m sestamibi (MIBI) in the extracardiac area due to unusual causes on myocardial perfusion single photon emission computed tomography (SPECT) studies. Seven patients are presented in whom incidental extracardiac findings were observed during the interpretation of the raw data besides the routine evaluation of myocardial reconstructed SPECT slices. These 7 patients were detected out of 582 consecutive patients (1.2%) who had myocardial perfusion SPECT with Tc-99m MIBI. The findings on the raw data led to additional reconstruction of thoracic SPECT images and eventually detailed examination of the extracardiac area. Two of the patients underwent surgery because of incidental extracardiac findings (thymoma and multinodular goiter) on cardiac scintigraphy. Other causes of increased extracardiac activity were the intestine protruded through the left hemithorax, uptake in the pulmonary arterial wall, and pulmonary interstitial fibrosis due to sarcoidosis. The reasons for decreased Tc-99m MIBI accumulation in the extracardiac area in the 2 other patients were significantly dilated pulmonary arteries and hydatic cyst, which were not defined before to our knowledge. Familiarity with the normal biodistribution and variable uptake patterns in the raw images becomes necessary during the interpretation of myocardial SPECT in order not to miss very unusual incidental extracardiac uptake or information that could lead to alteration in patient management. Potential underlying mechanisms of extracardiac Tc-99m MIBI accumulation are discussed, and the literature about noncardiac Tc-99m MIBI findings detected on myocardial perfusion SPECT studies was reviewed.

Thallium-201 myocardial SPECT in left bundle branch block: Diagnosis of myocardial ischemia with a disease-specific reference database

The aim of this study was to assess the value of a myocardial perfusion single photon emission computed tomography (SPECT) reference file for patients with left bundle branch block (LBBB). Tl-201 stress-redistribution myocardial perfusion SPECT studies of patients with complete, permanent LBBB were reviewed retrospectively. To develop a reference database, 18 patients with a low likelihood of coronary artery disease (CAD) were selected. Left ventricular regional average and standard deviation (SD) values of the reference file images were calculated. The diagnostic performance was tested on perfusion images of 49 patients with LBBB, undergoing both scintigraphic and coronary angiographic evaluation, and was compared with a commercial quantitative analysis system using a general reference database. The LBBB reference file performed significantly better in detecting epicardial CAD than did the general reference database (receiver operating characteristic area under the curve 0.835 +/- 0.06 vs 0.580 +/- 0.08, p < .01). Disease localization also was improved significantly in the territory of the left anterior descending and of the right coronary arteries. The use of a reference file of patients with LBBB and a low likelihood of CAD aids the detection and the localization of myocardial ischemia on Tl-201 myocardial SPECT images of this patient group.

The impact of acquisition protocol on the incidence of patient motion in 99mTc based myocardial perfusion SPECT

Myocardial perfusion single photon emission computed tomography (SPECT) artefacts introduced as a result of patient motion are known to produce artefacts that mimic the appearances of coronary artery disease. The advent of 99mTc based radiopharmaceuticals permits greater flexibility in patient scheduling, but variable physical demands of protocols may be associated with variations in the likelihood of patient motion. A prospective cross-sectional study of 177 myocardial perfusion SPECT patients using 99mTc tetrofosmin was used to compare the incidence of visually detectable motion for three protocol variations. The rotating cinematic display and sinograms of the datasets were visually assessed by two experienced technologist observers blinded to the second observer's responses and the clinical outcome. Among the 354 individual studies analysed, 43.8% contained visually detectable motion. 36.2% of rest studies demonstrated visually detectable motion compared to 51.4% for stress (P<0.05). Fifty per cent of 1 day rest/stress studies demonstrated motion, 39.3% of 2 day rest/stress studies demonstrated motion, and 46.8% of 2 day stress/rest studies demonstrated motion. One day 99mTc based myocardial perfusion SPECT studies are 1.3 times more likely to contain motion than the 2 day rest/stress protocol. The 2 day stress/rest protocol is 1.2 times more likely to contain motion than the 2 day rest/stress. The stress study is 1.4 times more likely to contain motion than the rest study while the stress study performed first in the sequence is 1.4 times more likely to contain motion than the stress study performed second. The 2 day rest/stress protocol is the preferred protocol to minimize patient motion.

Do myocardial perfusion SPECT and radionuclide angiography studies in adult patients with hypertrophic cardiomyopathy have prognostic implications?

Some myocardial perfusion single photon emission computed tomography (SPECT) and radionuclide ventriculography studies have suggested that the presence of regional perfusion defects and diastolic abnormalities could have prognostic implications in patients with hypertrophic cardiomyopathy (HC). The aim of this prospective study was to analyze the prognostic value of these techniques in adult patients with HC. One hundred one patients with HC (44 women; mean age, 54 +/- 16 years; 55% obstructive) were prospectively studied by means of myocardial perfusion SPECT and radionuclide angiography. Of these patients, 55 (54.4%) had an abnormal myocardial perfusion SPECT study: 28 (27.7%) had fixed defects and 41 (40.6%) had reversible defects; 15 (14.8%) of these patients had both types of defect. Of the patients, 16% had left ventricular ejection fraction lower than 60%, 25.7% had an abnormal peak filling rate, and 51% had an abnormal time to peak filling rate. During 5.6 +/- 2.7 years of follow-up, 13 patients (12.8%) died (heart failure 8 and sudden death in 5) and 14 had one or more severe complications develop (syncope in 6, angina III-IV in 4, dyspnea III-IV in 10, and acute myocardial infarction in 3). The summed difference score was higher in patients with cardiac death (2.2 +/- 2.3 vs 1.1 +/- 1.3, P = .008), and fixed defects were more prevalent in patients with severe complications (57% vs 21%, P = .01). In the Kaplan-Meier survival plot analysis, severe complications were more likely in patients with fixed defects (P = .01) or ejection fraction lower than 60% ( P = .01). Prognostic information from myocardial perfusion SPECT and radionuclide angiography has limited clinical significance with regard to cardiac death in adult patients with HC. However, the presence of fixed defects and lower ejection fraction in these patients has an adverse prognostic meaning for severe complications.

Gated stress-only 99mTc myocardial perfusion SPECT imaging accurately assesses coronary artery disease.

In today's cost containment environment it is important to consider changes to standard protocols which would reduce cost, particularly if there is no significant loss of diagnostic accuracy. The aim of the present study was to assess the usefulness of a gated stress-only Tc sestamibi protocol in comparison to conventional gated dual isotope rest-stress myocardial perfusion single photon emission computed tomography (SPECT) in the detection and localization of coronary artery disease (CAD). Sixty-five consecutive patients (65+/-10 years, 22 women) who had undergone conventional gated perfusion SPECT were chosen retrospectively. Fifty-three of these 65 patients had previous coronary arteriography, 45 with at least one stenosis, eight without stenosis, and 12 of these 65 patients had <5% likelihood of CAD. Three readers interpreted the gated stress-only and dual isotope studies in separate sessions blinded to (1). their previous readings, (2). the interpretation by others, and (3). the angiographic results. Readers used a five-point scale to score their visual and quantitative assessment of perfusion, function and compromised vascular territory. Their average score was used for determination of the accuracy by using receiver operating characteristic (ROC) analysis of the techniques. The areas under ROC curves were determined for the detection of CAD and localization of vascular territories. Fifty-four of these patients had 97 significant stress induced perfusion defects as determined by the CEqual quantitative program. The agreement between protocols for the assessment of reversibility in these 97 defects was analysed. There were no statistically significant differences between dual isotope rest/stress and gated stress-only studies for the detection and localization of CAD. The area under the dual isotope rest/stress ROC curve was 0.78+/-0.07 compared to the area under the gated stress-only ROC curve of 0.80+/-0.06, resulting in P=0.30. For the combined vessels comparison of the area under the dual isotope rest/stress ROC curve was 0.73+/-0.04 versus the area under the gated stress-only ROC curve of 0.74+/-0.04, resulting in P=0.27. Similar non-significant differences were obtained when comparing the area under the dual isotope versus gated stress-only ROC curves for the left anterior descending vascular territory (LAD, 0.61+/-0.08 vs 0.660.08, P=0.14), the left circumflex vascular territory (LCX, 0.82+/-0.07 vs 0.81+/-0.06, P =0.47) or the right coronary vascular territory (RCA, 0.80+/-0.06 vs 0.78+/-0.06, P=0.28). The analysis of the reversibility of stress induced perfusion defects yielded a global agreement between protocols of 93% (kappa=0.42). The differences were due to the expert readers, using the gated stress-only protocol, misinterpreting some patients with attenuation artefacts, subendocardial infarction and functional stunning. These results show that the lower cost gated stress-only myocardial Tc myocardial perfusion SPECT studies are comparable to the conventional dual isotope studies when the clinical question is the detection and localization of coronary artery disease. Nevertheless, we also showed that this approach is limited when attempting to interpret the reversibility of stress induced perfusion defects in patients who exhibit attenuation artefacts, subendocardial infarction and functional stunning.

Come on, baby, let's do the twist: Detecting and correcting cardiac torsion effects in myocardial perfusion SPECT

In this issue of the Journal of Nuclear Cardiology, Nichols et al describe a technique to detect cardiac torsion and use the information generated on a subjectby-subject basis to correct for any artifacts that cardiac torsion produces. Cardiac torsion is defined as the dynamic twisting component of cardiac motion about the apex-to-base axis as the heart contracts. This particular component of cardiac motion is not accounted for in routine myocardial perfusion single photon emission computed tomography (SPECT), even when such studies are acquired and processed in a gated fashion. Nichols et al hypothesized that maps of perfusion and wall thickening are motion-blurred by torsion and sought to “deblur” the maps based on the detected torsion. Imaging studies of cardiac motion, including torsion, in experimental animals and human beings have used a variety of modalities, including radiography, echocardiography, and magnetic resonance imaging (MRI). In general, these studies rely on “tagging” the myocardium with a series of reference points (eg, surgically attached steel markers for radiography, right ventricular insertion points or papillary muscles for echocardiography) or reference lines (eg, modulated magnetization grids for MRI) to directly assess movement (ie, change in location) of each point on or in the myocardium through the cardiac cycle. These studies have shown that most twisting occurs at the apex in normal persons, with different abnormal rotation patterns in the presence of cardiac disease. The study of cardiac torsion in the context of myocardial perfusion SPECT is potentially interesting in 2 ways: (1) cardiac torsion may generate artifacts that reduce diagnostic or quantitative accuracy, and (2) patterns of cardiac torsion may be (independently) diagnostic for cardiac disease. Nichols et al explicitly identified 3 goals for their work: (1) to document the frequency and degree of confidence with which it is feasible to detect torsion motion patterns, (2) to determine whether corrections for torsion improve myocardial perfusion and wall thickening quantitation, and (3) to discover whether abnormal twisting patterns seen by MRI are also detected by SPECT. In this regard, their work can be seen as the first step in addressing the two potential implications or uses of cardiac torsion detection in myocardial perfusion SPECT. Their first and third goals represent necessary prerequisites to accept their detection method as accurate; their second goal is the first step in determining whether cardiac torsion correction is important in myocardial perfusion SPECT. Nichols et al studied their approach in 52 subjects who underwent both technetium 99m sestamibi gated myocardial perfusion SPECT studies and contrast angiography. They divided the 52 subjects into 3 groups: (1) 12 subjects with normal angiography and gated myocardial perfusion SPECT results, (2) 12 subjects with abnormal angiography results and abnormal perfusion by SPECT, and (3) 28 subjects after angioplasty, representing a mixture of normal and abnormal perfusion, prior infarction, wall motion, and coronary artery bypass grafting. The authors developed a fully automated algorithm to detect and quantify torsion from the 8-frame gated SPECT data. The algorithm is based on determining the location of right ventricular insertion points (anterior and especially inferior wall insertion points) in the polar plot of each frame; the change in angular location of these points through the cardiac cycle represents torsion. In essence, their algorithm outputs a rotational (angular) shift at a given phase of the cardiac cycle; this shift is proportional to the magnitude of torsion, and torsion correction can be accomplished simply by rotating each polar map in the opposite direction by the corresponding shift. If this is performed before adding the 8 maps together (to simulate a “static” or ungated map), then the resultant static map does not contain the angular blurring that torsion would otherwise produce. Nichols et al found that torsion magnitude and patterns were consistent with those previously reported from MRI studies. They also found that torsion correcFrom Johns Hopkins University, Baltimore, Md. Reprint requests: Jonathan M. Links, PhD, Radiology Health Sciences/ Environmental Health, Johns Hopkins Medical Institute, 615 N Wolfe St, Baltimore, MD 21205-2179. J Nucl Cardiol 2002;9:561-2. Copyright © 2002 by the American Society of Nuclear Cardiology. 1071-3581/2002/$35.00 0 43/39/125917 doi:10.1067/mnc.2002.125917

Repeatability of automatic left ventricular cavity volume measurements from myocardial perfusion SPECT

Background. This study sought to assess the repeatability of automatic quantitative measurements of left ventricular (LV) cavity volumes in a large patient population (N = 926), to correlate those measurements to similarly obtained LV ejection fraction (LVEF) measurements, and to investigate the relationship between ungated and gated volumes. Methods. All 926 patients underwent ungated single photon emission computed tomography (SPECT) immediately followed by 8-frame gated SPECT. LV cavity volumes were automatically measured from ungated (V), summed gated (SUMV), end-systolic (ESV) and end-diastolic (EDV) images, and LVEFs derived from the latter 2. Results. Repeatability (SUMV vs V) was very good overall (6.4% ± 6.6%), further improving for volumes 25 mL (5.7% ± 5.5%) and 40 mL (5.2% ± 5.0%). Exponential regression between ESV and LVEF (r = 0.925, SEE = 15.0 mL), EDV and LVEF (r = 0.802, SEE = 24.2 mL), and SUMV and LVEF (r = 0.867, SEE = 19.7 mL) was also very good. Summed gated volumes were closer to ESV than to EDV (43.3% ± 8.8% of EDV-ESV range). SUMV <50 mL and SUMV 110 mL were good substitutes for LVEF 50% and LVEF <40% (93.4% and 97.1%, respectively). Conclusion. Automatic quantitative measurements of gated and ungated volumes with our algorithm are repeatable, correlate well with other global myocardial parameters, and may contribute important additional information to that conventionally provided by myocardial perfusion SPECT studies.

Quantitative single-photon emission computed tomography: Basic and clinical considerations

Although quantitative single-photon emission computed tomography (SPECT) has been the goal of much research effort for a number of years, only recently has it received wide interest, especially for clinical applications. It has been increasingly recognized that the achievement of quantitative SPECT will increase the accuracy of measurements, such as dimensions of specific regions of interest, absolute amount of radioactivity, and dosimetry calculations, and substantially reduce reconstruction image artifacts and distortions, thus, greatly improving clinical diagnosis. This article provides a review of the definition of terms, major factors affecting SPECT quantitation and their degrading effects on SPECT image quality, and methods to compensate for these effects. Compensation methods include those that make certain approximations for ease of implementation and those that provide more accurate compensation by modeling the imaging process more exactly, usually at the cost of increased complexity and computational requirements. Different reconstruction and compensation methods may be compared through the use of phantom cardiac and brain SPECT studies. The clinical efficacy of the methods may be demonstrated by applying them to a clinical thallium-201 myocardial perfusion SPECT study. The results clearly demonstrate that, by modeling the imaging process and/or image degrading factors three-dimensionally, quantitative reconstruction and compensation methods provide the best image quality and quantitative accuracy. Important research efforts and developmental work being conducted currently to bring quantitative SPECT into routine clinical use are also discussed.