Impact of combined supine and prone myocardial perfusion imaging using an ultrafast cardiac gamma camera for detection of inferolateral coronary artery disease

Multi-center study of inter-rater reproducibility, image quality, and diagnostic accuracy of CZT versus conventional SPECT myocardial perfusion imaging

BACKGROUND

Cadmium-zinc-telluride (CZT)-based detectors exhibit higher diagnostic sensitivity in myocardial perfusion imaging (MPI) than conventional Anger-MPI for detection of coronary artery disease (CAD); however, reduced specificity and diagnostic accuracy of CZT-MPI were observed. This study aims to compare these different camera systems and to examine the degree of inter-rater reproducibility among readers with varying experience in MPI.

METHODS

83 patients who underwent double stress/rest examinations using both a CZT and conventional SPECT cameras within one visit were included. Anonymized and randomized MPI-images were distributed to 15 international readers using a standardized questionnaire. Subsequent coronary angiography findings of ten patients served as a reference for analysis of sensitivity and specificity.

RESULTS

Image quality was significantly better in CZT-MPI with significantly lower breast attenuation (P < 0.05). CZT-MPI exhibited higher sensitivity than Anger-MPI (87.5% vs. 62.5%) and significantly reduced specificity (40% vs. 100%). Readers experienced with both camera systems had the highest inter-rater agreement indicating higher reproducibility (CZT 0.54 vs. conv. 0.49, P < 0.05).

CONCLUSIONS

Higher diagnostic sensitivity of CZT-MPI offers advantages in detection of CAD yet potentially of at the cost of reduced specificity, therefore it requires special training and a differentiated evaluation approach, especially for non-experienced readers with such camera systems.

Diagnostic performance of prone-only myocardial perfusion imaging versus coronary angiography in the detection of coronary artery disease: A systematic review and meta-analysis

STUDY DESIGN

Although prone position is considered as a complementary protocol in myocardial perfusion imaging (MPI), there is no consensus on its capability to find coronary artery disease (CAD), independently. The primary aim of this review was to report pooled sensitivity and specificity for prone position MPI in detection of CAD. In addition, the results were compared to the supine position's performance.

METHODS

Electronic bibliographic databases, The Cochrane Library, Web of Science (Science and Social Science Citation Index), Scopus, PubMed, and EMBASE until the end of June 2020 were searched. Studies were included based on the inclusion criteria of (1) evaluated the prone position MPI, (2) defined CAD with coronary angiography (CAG), using the threshold of ≥ 50% stenosis, (3) Adequate data were provided to extract the diagnostic performance. QUADAS-2 tool was utilized to assess the quality of included studies. Pooled sensitivity and specificity were calculated for prone and supine positions, separately. The hierarchical summary ROC curves were also drawn.

RESULTS

Ten individual studies with the data of the 1490 patients for the prone position and 1138 patients for the supine position were included. Pooled sensitivity and specificity for the prone position were 83% and 79%, respectively. These results were calculated for the supine position as the sensitivity of 86% and specificity of 67%. The pooled sensitivity and specificity of the prone position in detecting the right coronary artery territory defects were 70% and 84%, in turn.

CONCLUSION

In the suspicion for the CAD, prone position with comparable sensitivity and higher specificity can be an acceptable alternative to the supine position as the standard method. Also, in the cases of possible defects in the RCA territory, prone position showed to be a superior standard.

Attenuation correction in CZT myocardial perfusion imaging comparison of supine-prone and low-dose CT-corrected supine acquisitions

AIMS

The study aimed to investigate whether additional prone imaging delivers comparable results to supine imaging with low-dose computed tomography (CT) attenuation correction (CTAC) in cadmium, zinc and telluride (CZT) myocardial perfusion imaging.

METHODS AND RESULTS

Thirty-four patients with an indication for myocardial perfusion imaging were studied with a CZT camera in the supine and then prone position. Furthermore, a low-dose CT was acquired. Three data sets were reconstructed and considered for analysis: (1) supine CZT, (2) supine CZT with CTAC and (3) supine CZT with additional prone CZT. Based on 17-segment polartomograms, we compared radiopharmaceutical uptake percentage, summed stress score (SSS), summed rest score (SRS), summed difference score (SDS), total ischemic and scarred segments, and finally scan classification and clinical decision-making. SSS of supine/supine-CTAC/supine-prone was 341/229/253 (P < 0.05), SRS was 246/156/164 (P < 0.05) and SDS was 104/88/96 (ns), respectively. Total ischemic segments were 65/67/65 (ns) and total scarred segments 96/62/69 (P < 0.05), respectively. The frequency of normal scans was highest for supine-prone, followed by supine-CTAC and supine (41/35/24%, respectively). Supine imaging indicated 23% of patients for invasive coronary angiography, both supine-CTAC and supine-prone 18%. These two showed a significant intercorrelation.

CONCLUSION

Additional prone imaging and CTAC are mainly correct for the amount and extent of myocardial scars. Both methods increase the frequency of normal scans and show a significant agreement in clinical decision-making. Additional prone imaging appears as a useful alternative when a low-dose CT for attenuation correction is not available.

Current Status of Myocardial Perfusion Imaging With New SPECT/CT Cameras

Myocardial perfusion imaging (MPI) with Single-Photon Emission Computed Tomography (SPECT) has a major role in the management of coronary artery disease. Recent technological advances regarding SPECT detectors with the use of solid-state detectors has allowed for improved imaging quality since a decade with dramatic dose and/or time reduction of imaging protocols due to improved sensitivity and spatial resolution, and is now performed as a routine exam. Interestingly, this new technology has modified our everyday practice, from acquisition protocols (low dose and ultra-fast protocols) to image semiology. Numerous studies have shown how these technical advances have allowed for improved patient management, with similar or improved diagnostic and prognostic information derived from MPI. These improvements have also led to the straightforward implementation of myocardial blood flow measurement. This article reviews the current status of MPI using new SPECT and SPECT/CT cameras.

Prospective diagnostic performance of semiconductor SPECT myocardial perfusion imaging: wall thickening analysis reduces the need for an additional prone acquisition

PURPOSE

To determine whether the assessment of regional wall thickening (WT) in addition to myocardial perfusion from stress supine acquisitions could compensate for the lack of prone acquisition and the corresponding decrease in the diagnostic performance of SPECT myocardial perfusion imaging (MPI) in patients with known or suspected coronary artery disease (CAD).

METHODS

The study group comprised 41 patients (123 vessels) with known or suspected CAD prospectively recruited for systematic prone and supine ²⁰¹Tl stress SPECT MPI. The diagnostic performance of SPECT MPI was determined for various image sets including nongated supine images (supine NG), nongated combined prone and supine images (prone and supine NG) and gated supine images, allowing WT evaluation from NG images in addition to perfusion (supine NG + WT) using invasive coronary angiography and fractional flow reserve as the gold standards.

RESULTS

The rate of false positives was significantly higher among the supine NG images (20.8%) than among either the prone and supine NG or the supine NG + WT images (3.3% and 2.7%, respectively, P < 0.05 vs. supine NG). Consequently, specificity was higher for the prone and supine NG images than for the supine NG images (96.1% vs. 76.1%, P < 0.01) and was highest for the supine NG + WT images (96.8%, P not significant vs. prone and supine NG), without significant differences in sensitivity (80.0%, 86.6% and 73.3%, respectively, P not significant for all comparisons).

CONCLUSION

The diagnostic performance of supine stress SPECT MPI is improved when WT assessment of ischaemic segments is used as an additional diagnostic criterion to values not significantly different from those with combined prone and supine acquisitions.

EANM procedural guidelines for myocardial perfusion scintigraphy using cardiac-centered gamma cameras

An increasing number of Nuclear Medicine sites in Europe are using cardiac-centered gamma cameras for myocardial perfusion scintigraphy (MPS). Three cardiac-centered gamma cameras are currently the most frequently used in Europe: the D-SPECT (Spectrum Dynamics), the Alcyone (Discovery NM 530c and Discovery NM/CT 570c; General Electric Medical Systems), and the IQ-SPECT (Siemens Healthcare). The increased myocardial count sensitivity of these three cardiac-centered systems has allowed for a decrease in the activities of radiopharmaceuticals injected to patients for myocardial perfusion imaging and, consequently, radiation exposure of patients. When setting up protocols for MPS, the overall objective should be to maintain high diagnostic accuracy of MPS, while injecting the lowest activities reasonably achievable to reduce the level of radiation exposure of patient and staff. These guidelines aim at providing recommendations for acquisition protocols and image interpretation using cardiac-centered cameras. As each imaging system has specific design and features for image acquisition and analysis, these guidelines have been separated into three sections for each gamma camera system. These recommendations have been written by the members of the Cardiovascular Committee of EANM and were based on their own experience with each of these systems and on the existing literature.

Diagnostic value of cadmium-zinc-telluride myocardial perfusion imaging versus coronary angiography in coronary artery disease: A PRISMA-compliant meta-analysis

BACKGROUND

Rapid progress has been made in research of cadmium-zinc-telluride (CZT) technology in the last few years, which might serve as a new method to diagnose coronary artery disease. However, compared with coronary angiography, the diagnostic value of CZT is still controversial. We aimed to evaluate diagnosis value of coronary angiography versus CZT in coronary artery disease.

METHODS

We searched the database for eligible researches associated with CZT- myocardial perfusion imaging (MPI) and invasive coronary angiography, extracted the relevant data, and rigorously screened it according to the inclusion and exclusion criteria. The accuracy indicators included sensitivity, specificity, accuracy, positive and negative likelihood ratios.

RESULTS

According to the inclusion and exclusion criteria, we finally found 20 studies containing 2350 patients in this search. Pooled results showed that sensitivity of CZT-MPI was 0.84% and 95% confidence interval (95% CI): 0.78 to 0.89, specificity was 0.72, 95% CI (0.62-0.76), the specificity was lower apparently. The positive likelihood ratio was 3.0, 95% CI (2.4-3.8), the negative likelihood ratio was 0.22, 95% CI (0.16-0.31), diagnostic odds ratio was 14, 95% CI (7.84-17.42).

CONCLUSION

This meta-analysis showed that CZT-MPI had satisfactory sensitivity and specificity for diagnosing coronary artery disease. Larger studies are required for further evaluation.

SPECT myocardial ischemia in the absence of obstructive CAD: Contribution of the invasive assessment of microvascular dysfunction

Coronary microvascular dysfunction has recently emerged as a major independent prognostic factor and can be invasively assessed by coronary flow reserve (CFR) and the index of microvascular resistance (IMR). The incremental prognostic value of myocardial ischemia from SPECT myocardial perfusion imaging (MPI) over clinical characteristics, cardiac risk factors, and stress test data for the prediction of hard cardiac events (myocardial infarction and cardiac death) has been well demonstrated over the last two decades regardless of the absence or presence of epicardial CAD. Recently developed semi-conductor, cardiac-dedicated cameras allow for decreased acquisition times and systematic procubitus and decubitus acquisitions thereby limiting the occurrence of false positives historically attributable to artefactual motion, attenuation, and digestive artifacts. It is therefore likely that pathophysiological causes rather than acquisition artifacts might underlie SPECT perfusion abnormalities. Here, we report four representative examples of patients presenting with ischemia in the setting of no obstructive CAD and normal fractional flow reserve together with elevated IMR and low CFR. The results indicate that ischemia from SPECT MPI could result from microvascular dysfunction in patients without obstructive CAD and should be considered as a prognostic factor for hard cardiac events.

Comparison of CTAC and prone imaging for the detection of coronary artery disease using CZT SPECT

Background

Cadmium-zinc-telluride (CZT) cameras have improved the evaluation of patients with chest pain. However, inferior/inferolateral attenuation artifacts similar to those seen with conventional Anger cameras persist. We added prone acquisitions and CT attenuation correction (CTAC) to the standard supine image acquisition and analyzed the resulting examinations.

Methods and results

Seventy-two patients referred for invasive coronary angiography (CAG), and who also underwent rest/stress myocardial perfusion imaging (MPI) on a CZT camera in the supine and prone positions plus CTAC imaging, to examine known or suspected CAD between April 2013 and March 2014 were included. A sixteen-slice CT scan acquired on a SPECT/CT scanner between rest and stress imaging provided data for iterative reconstruction. Sensitivity, specificity, accuracy, and positive and negative likelihood ratios (LRs) were calculated to compare MPI with CAG on a per-patient basis. Per-patient sensitivity, specificity, and accuracy of supine images to predict coronary abnormalities on CAG were 35% [95% confidence interval (CI) 19–52], 86% (95% CI 80–92), and 74% (95% CI 66–82); those of prone imaging were 65% (95% CI 45–81), 82% (95% CI 76–87), and 78% (95% CI 68–85); and those of CTAC were 59% (95% CI 41–71), 93% (95% CI 87–97), and 85% (95% CI 76–91), respectively.

Conclusions

Prone acquisition and CTAC images improve the ability to assess the inferior/inferolateral area.

Diagnostic Accuracy of Myocardial Perfusion Imaging With CZT Technology: Systemic Review and Meta-Analysis of Comparison With Invasive Coronary Angiography

OBJECTIVES

This study sought to summarize the evidence on stress myocardial perfusion imaging (MPI) using cadmium-zinc-telluride (CZT) technology for the diagnosis of obstructive coronary artery disease (CAD). The CZT cameras are newly introduced, and comparative data with the conventional Anger technology (Anger-MPI) are lacking.

BACKGROUND

The diagnostic accuracy of Anger-MPI for detection of angiographically significant CAD is well established; however, less evidence is available on the diagnostic accuracy of CZT-MPI.

METHODS

Clinical studies comparing CZT-MPI and invasive coronary angiography were systematically searched and abstracted. Calculations of diagnostic accuracy, including sensitivity, specificity, likelihood ratios, and diagnostic odds ratio, were obtained with fixed and random effects, reporting point estimates and 95% confidence intervals.

RESULTS

Based on our search, a total of 16 studies (N = 2,092) were included. The sensitivity of CZT-MPI was 0.84 (95% confidence interval [CI]: 0.78 to 0.89), whereas the specificity of 0.69 (95% CI: 0.62 to 0.76) was significantly reduced. The positive likelihood ratio was 2.73 (95% CI: 2.21 to 3.39), the negative likelihood ratio was 0.24 (95% CI: 0.17 to 0.31), and the diagnostic odds ratio was 11.93 (95% CI: 7.84 to 17.42). At subgroup and meta-regression analyses, the diagnostic accuracy between D-SPECT and Discovery cameras was similar (p = 0.711) and not impacted upon by smaller sample size studies (p = 0.573).

CONCLUSIONS

CZT-MPI has satisfactory sensitivity for angiographically significant CAD, but its suboptimal specificity warrants further development and research.

Performance of cardiac cadmium-zinc-telluride gamma camera imaging in coronary artery disease: a review from the cardiovascular committee of the European Association of Nuclear Medicine (EANM)

The trade-off between resolution and count sensitivity dominates the performance of standard gamma cameras and dictates the need for relatively high doses of radioactivity of the used radiopharmaceuticals in order to limit image acquisition duration. The introduction of cadmium-zinc-telluride (CZT)-based cameras may overcome some of the limitations against conventional gamma cameras. CZT cameras used for the evaluation of myocardial perfusion have been shown to have a higher count sensitivity compared to conventional single photon emission computed tomography (SPECT) techniques. CZT image quality is further improved by the development of a dedicated three-dimensional iterative reconstruction algorithm, based on maximum likelihood expectation maximization (MLEM), which corrects for the loss in spatial resolution due to line response function of the collimator. All these innovations significantly reduce imaging time and result in a lower patient's radiation exposure compared with standard SPECT. To guide current and possible future users of the CZT technique for myocardial perfusion imaging, the Cardiovascular Committee of the European Association of Nuclear Medicine, starting from the experience of its members, has decided to examine the current literature regarding procedures and clinical data on CZT cameras. The committee hereby aims 1) to identify the main acquisitions protocols; 2) to evaluate the diagnostic and prognostic value of CZT derived myocardial perfusion, and finally 3) to determine the impact of CZT on radiation exposure.

Temporal trends of stress myocardial perfusion imaging: Influence of diabetes, gender and coronary artery disease status

INTRODUCTION

Temporal trends of myocardial perfusion imaging (MPI) among diabetics and non-diabetics and the influence of gender and prior coronary artery disease (CAD) status has not been previously investigated.

MATERIALS AND METHODS

Consecutive patients who underwent clinically indicated stress-MPI over a 17-year period (1996 through 2012) were studied. Data were collected prospectively as a part of the ongoing clinical databases. Study patients were divided into 4 temporal subgroups (1996 to 2000, 2001 to 2004, 2005 to 2008 and 2009 to 2012) to compare the trends of cardiac risk factors and the frequency of abnormal and ischemic MPI.

RESULTS

Of 78,344 total stress MPI studies, 30.2% were in diabetics. The frequency of abnormal MPI studies, while substantially higher in diabetics, significantly declined over time both in diabetics (53.6% in 1996 to 39.8% in 2012) and non-diabetics (37% in 1996 to 27.4% in 2012), despite an increase in the cardiac risk factor profile. Furthermore, among patients with no known CAD, the temporal prevalence of abnormal MPI was highest in diabetic men (57.5% in 1996 to 31.9% in 2012), lowest in non-diabetic women (18.8% in 1996 to 11% in 2012), and both intermediate and comparable in non-diabetic men and diabetic women (36.4% and 35.7% in 1996 and 20.7% and 17.5% in 2012, respectively).

CONCLUSIONS

Despite a temporal reduction in the prevalence of abnormal studies from 1996 through 2012, stress MPI continues to play an important clinical role, particularly in diabetics, men and patients with known-CAD.

Radiation dose and prognosis of ultra-low-dose stress-first myocardial perfusion SPECT in patients with chest pain using a high-efficiency camera

Although SPECT myocardial perfusion imaging (MPI) provides valuable information about patients with chest pain, there is growing concern regarding its radiation burden and lengthy duration. New high-efficiency (HE) cameras and stress-first protocols both offer the potential to markedly reduce radiation. No previous study has assessed outcomes and radiation doses of patients undergoing MPI on an HE-SPECT camera using an ultra-low-dose stress-first protocol.

METHODS

One hundred patients presenting to the emergency department with chest pain who were candidates for stress-first MPI underwent injection of approximately 185 MBq (5 mCi) of (99m)Tc-tetrofosmin at peak stress, followed by supine and prone imaging on an HE-SPECT camera. Same-day rest imaging was performed on patients with any abnormality on imaging after stress. Radiation effective dose was calculated from administered and residual activities. Patients were contacted 3 mo after discharge, and electronic records were accessed to evaluate the need for reevaluation for chest pain, additional imaging, or cardiac events.

RESULTS

Stress-only imaging was performed in 69 patients, for whom radiation effective dose averaged 0.99 mSv and study duration, 117 min. Radiation dose averaged 2.22 mSv over all patients. At 3 mo, 96 patients were free of major adverse cardiac events, repeat hospital chest pain evaluation, and repeat imaging or stress testing. One year after MPI and hospital discharge, all patients were living and without acute coronary syndrome.

CONCLUSION

HE-SPECT stress-only imaging can be performed in more than two thirds of chest pain patients without a high pretest probability of a stress perfusion defect, with excellent prognosis, a radiation dose averaging 1 mSv, and a test duration of less than 2 h.

External validation of models for estimating pretest probability of coronary artery disease among individuals undergoing myocardial perfusion imaging

BACKGROUND

Clinical decisions regarding the appropriateness of noninvasive cardiac imaging among individuals with suspected coronary artery disease (CAD) rely heavily on the pretest probability of coronary artery disease (pCAD), often estimated from clinical prediction models. These models have not been validated among individuals undergoing noninvasive myocardial perfusion imaging (MPI) for suspected CAD. Thus, the objective of this study was to compare the extent of agreement and predictive performance between four published pCAD models among individuals undergoing positron emission tomography (PET MPI).

METHODS

This cross-sectional study performed at a cardiac referral center included 2383 patients with stable symptoms undergoing PET MPI for the evaluation of suspected CAD. pCAD was estimated on a per-patient basis using four distinct pCAD estimation models. All pCAD estimates were calibrated to a common standard to allow fair comparisons of agreement and predictive performance. Pairwise pCAD model disagreement was defined as percent discordance in classifying patients as low versus intermediate pCAD (<10% vs. ≥10%). Predictive performance was quantified by c-statistics with abnormal myocardial perfusion as a binary outcome.

RESULTS

Pairwise pCAD estimates demonstrated non-negligible disagreement with percent discordance between models ranging from 11% to 23%. Agreement worsened when higher thresholds for distinguishing low-intermediate pCAD were employed. All pCAD models demonstrated poor predictive performance for identifying abnormal stress perfusion with c-statistics ranging from 0.554 to 0.616.

CONCLUSIONS

pCAD estimation models showed suboptimal agreement and poor predictive performance in patients undergoing PET MPI. The transportability of pCAD models to MPI patients should be questioned and further evaluated in future studies.