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Myocardial perfusion images from patient (patient 99 in this study) with anterior and septal ischemia. (A) High-efficiency SPECT image. Radiation effective dose from myocardial perfusion imaging was 0.77 mSv for stress, 2.57 mSv for rest. (B) Invasive coronary angiogram shows 99% stenosis of left anterior descending artery (arrowhead).
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While SPECT 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 potential to markedly reduce radiation. No previous study assessed outcomes and radiation doses of patients undergoing MPI...
Context in source publication
Context 1
... the development of HE-SPECT cameras and the validation of stress-first/stress-only protocols (13) offer the potential to mark- edly reduce radiation dose from MPI. Their combination makes possible the performance of a complete nuclear stress test using 99m Tc-tetrofosmin at a radiation dose of 1 mSv or less (Fig. 2) and identification of ischemia with a single-day protocol at a radiation dose under 5 mSv (Fig. 3). However, clinical outcomes in patients scanned with such a stress-first ULD HE-SPECT protocol have not been previously ...
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Citations
... This is particularly relevant since patients with normal regional myocardial perfusion on SPECT MPI may be more effectively risk stratified by using measures such as absolute myocardial blood flow (8,9) or coronary artery calcification (10,11). Additionally, patients with a low likelihood of abnormal perfusion may be candidates for stress-first imaging (and evaluated for stress only imaging) to reduce radiation exposure (12). However, SPECT (or PET) MPI could be particularly useful in patients with a high risk of ischemia since this may help target more aggressive therapies. ...
Background:
Accurately predicting which patients will have abnormal perfusion on MPI based on pre-test clinical information may help physicians make test selection decisions. We developed and validated a machine learning (ML) model for predicting abnormal perfusion using pre-test features.
Methods:
We included consecutive patients who underwent SPECT MPI, with 20,418 patients from a multi-center (5 sites) international registry in the training population and 9019 patients (from 2 separate sites) in the external testing population. The ML (extreme gradient boosting) model utilized 30 pre-test features to predict the presence of abnormal myocardial perfusion by expert visual interpretation.
Results:
In external testing, the ML model had higher prediction performance for abnormal perfusion (area under receiver-operating characteristic curve [AUC] 0.762, 95% CI 0.750-0.774) compared to the clinical CAD consortium (AUC 0.689) basic CAD consortium (AUC 0.657), and updated Diamond-Forrester models (AUC 0.658, p < 0.001 for all). Calibration (validation of the continuous risk prediction) was superior for the ML model (Brier score 0.149) compared to the other models (Brier score 0.165 to 0.198, all p < 0.001).
Conclusion:
ML can predict abnormal myocardial perfusion using readily available pre-test information. This model could be used to help guide physician decisions regarding non-invasive test selection.
... Аналогичные данные получили J. Oddstig с соавт., при этом используемый низкодозный протокол дал возможность уменьшить лучевую нагрузку с 9,3 до 5,8 мЗв за счет снижения вводимой активности с 4,0 до 2,5 МБк на килограмм массы тела при сохранении сопоставимого качества изображения [7]. В дальнейшем было проведено большое количество исследований, в которых показали, что использование низкодозного протокола на CZT-камерах дает возможность не только получить качественные изображения перфузии миокарда левого желудочка (ЛЖ), но и сократить время исследования, а также значительно снизить лучевую нагрузку на пациента [9][10][11][12][13][14][15][16]. ...
p>Myocardial perfusion imaging is considered one of the leading non-invasive diagnostic tools for the assessment of patients with known or suspected coronary artery disease and other cardiac pathologies. The technical improvement of the currently used gamma-tomographic devices has increased the diagnostic capability of this technique. In recent years, the use of dedicated cardiac SPECT cameras with solid-state cadmium–zinc–telluride (CZT) technology has increased in nuclear imaging. These new CZT technologies have several advantages over existing scanner models. The development of new CZT detectors and their collimator configuration has increased scanning sensitivity and spatial resolution values. Also, due to the significantly higher sensitivity of new CZT detectors and new methods of data processing, radiologists have already introduced new scanning protocols and methods for radionuclide assessment of myocardial blood flow, reserve and non-invasive visualisation of the functioning of the sympathetic nervous system into clinical practice. The purpose of this review is to provide data on the main technical characteristics of gamma cameras equipped CZT detectors as well as the current possibilities of using CZT cameras for examining patients with various cardiovascular diseases.
Received 1 April 2020. Revised 22 April 2020. Accepted 30 April 2019.
Funding: The work is supported by a grant of the Russian Science Foundation No. 17-75-20118.
Conflict of interest: Authors declare no conflict of interest.
Author contributions
Conception and study design: S.M. Minin, K.V. Zavadovky, A.B. Romanov
Drafting the article: S.M. Minin, K.V. Zavadovky, N.A. Nikitin, A.V. Mochula, A.B. Romanov
Critical revision of the article: S.M. Minin, K.V. Zavadovky
Final approval of the version to be published: S.M. Minin, K.V. Zavadovky, N.A. Nikitin, A.V. Mochula, A.B. Romanov</p
... In symptomatic patients who present to the ED (or inpatients) with ACS features that are consistent with non-STEMI or ACS (increase in Tn levels or dynamic ECG changes) (scenario 11), MPI PET is not indicated, as these patients are at high risk and, thus, they are commonly referred to further triage with invasive coronary angiography and potential intervention according to standard clinical practice (49,50). In scenario 12, this group of patients with some type of unstable angina or ACS and with positive Tn results but with neither an increase in Tn levels later nor dynamic ECG changes, PET MPI was seen as appropriate for further cardiovascular risk stratification and triage of the patient (27,28,32,(49)(50)(51)(52)(53)(54). ...
... Scenarios 13-15 address the role of PET MPI in patients who present to the ED (or inpatients) with chest pain or equivalent symptoms with or without known CAD who have equivocal Tn levels or a temporal Tn pattern not consistent with ACS (scenario 13); patients who present to the ED (or inpatients) with symptoms of chest pain that may be due to ACS, with normal Tn levels and no dynamic ECG changes (scenario 14); and patients who present to the ED (or inpatients) with symptoms of chest pain that are unlikely to be due to ACS, with normal Tn levels and no dynamic ECG changes (scenario 15). Given the clinical constellation and standard clinical practice (27,28,32,(49)(50)(51)(52)(53)(54), these scenarios were seen as appropriate. ...
... Following the ASNC guidelines, the range of total radiation exposure of a 70 kg patient undergoing a stress/rest 99m Tc perfusion study is now 9-13.5 mSv with an Anger camera and a ratio of rest to stress activity of 3:1. 5 The technical advancements of solid-state SPECT cameras has been used to reduce patient's radiation exposure up to 50% while preserving diagnostic accuracy, 15 regional perfusion defect size and functional parameters 16 The lowest total radiation exposure with current SPECT MPI (1 mSv) can be accomplished clinically by performing stress-only imaging with a solid-state camera system. 17 Noteworthy, since each gamma camera has specific design and features for image acquisition and analysis, the last EANM guidelines have been separated into three different sections, one for each cardiac-centered camera commercially available. 7 The results of the present study referred to a stress followed by rest imaging procedure (stress-first protocol), which is advantageous in term of patient doses since, in the case of normal stress study (normal perfusion, volumetric, kinetics and function), the study at rest can be avoided (stress-only protocol). ...
Background
This investigation used image data generated by an anthropomorphic phantom to determine the minimal 99mTc rest-stress activity concentration ratio (R) able to minimize the ghosting effect in the single-day stress-first myocardial perfusion imaging, using different positions of the perfusion defect (PD), scanners and reconstruction protocols.MethodsA cardiac phantom with a simulated PD was imaged under different R using different gamma cameras and reconstruction algorithms. The residual activity from precedent stress administration was simulated by modeling effective half-times in each compartment of the phantom and assuming a delay of 3 hours between the stress and rest studies. The net contrast (NC) of the PD in the rest study was assessed for different R, PD positions and scanner/software combinations. The optimal R will be the one that minimize the NC in the rest imagesResultsThe activity concentration ratio R, the position of the PD and the scanner/software combinations were all main effects with a statistically significant impact on the NC, in decreasing order of relevance. The NC diminished significantly only for R values up to 2. No further improvement was observed for NC for R values above 2 and up to 3. NC was significantly higher in anteroseptal than in posterolateral positions of the PD and higher for solid-state cameras.ConclusionsA rest-stress activity concentration ratio R of 2 in single-day stress-first myocardial perfusion imaging is enough to achieve the maximum net contrast in the PD. This ratio should be used to optimize patient’s radiation exposure.
... A low-dose stress MPI protocol by CZT camera provides a high diagnostic performance and a dramatic reduction in patient radiation doses [24]. Tracer activity may be reduced using CZT-SPECT, resulting in a radiation dose exposure of 2-3 mSv for a complete rest and stress study, placing nuclear MPI at the same level with PET and even below diagnostic invasive angiography [25,26]. Our results suggest that MPR by dynamic CZT-SPECT, with a tracer dose lower than previous studies, is useful in predicting the presence of obstructive CAD. ...
Background
We measured myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) by a dynamic low-dose CZT-SPECT protocol in patients with suspected or known coronary artery disease (CAD) and investigated the capability of dynamic data in predicting obstructive CAD. A total of 173 patients with suspected or known CAD underwent dynamic CZT-SPECT after the injection of 155 MBq and 370 MBq of 99mTc-sestamibi for rest and stress imaging, respectively. Standard rest and stress imaging were performed at the end of each dynamic scan. A total perfusion defect (TPD) < 5% were considered normal. Obstructive CAD was defined as ≥ 70% stenosis at coronary angiography.
Results
Global MPR was lower (p < 0.05) in patients with abnormal compared with those with normal MPI (2.40 ± 0.7 vs. 2.70 ± 0.8). A weak, albeit significant correlation between TPD and MPR (r = − 0.179, p < 0.05) was found. In 91 patients with available angiographic data, hyperemic MBF (2.59 ± 1.2 vs. 3.24 ± 1.1 ml/min/g) and MPR (1.96 ± 0.7 vs. 2.74 ± 0.9) were lower (both p < 0.05) in patients with obstructive CAD (n = 21) compared with those without (n = 70). At univariable analysis, TPD, hyperemic MBF, and MPR were significant predictors of obstructive CAD, whereas only MPR was independent predictor at multivariable analysis (p < 0.05). At per vessels analysis, regional hyperemic MBF (2.59 ± 1.2 vs. 3.24 ± 1.1 ml/min/g) and regional MPR (1.96 ± 0.7 vs. 2.74 ± 0.9) were lower in the 31 vessels with obstructive CAD compared with 242 vessels without (both p < 0.05).
Conclusions
In patients with suspected or known CAD, MPR assessed by low-dose dynamic CZT-SPECT showed a good correlation with myocardial perfusion imaging findings and it could be useful to predict obstructive CAD.
... An abundance of literature has reported the benign prognosis of patients with normal stress-only testing in different patient populations, 1-3 radiotracers, 4 and imaging approaches. 1,3,5,6 Stress-only imaging is associated with up to 60% reduction in effective radiation exposure compared with a standard 1day stress-rest exam 7 and shortening of examination time. Despite these substantial benefits, stress-only MPI protocols remain severely under-utilized (11.9% of SPECT MPI worldwide and <3% in the USA) 8,9 suggesting that optimal implementation of stress-only imaging has not yet been achieved. ...
... While the variables were specified by Chang et al., 1 exact cut-offs were not reported, therefore the thresholds were derived from a related study. 5 To be consistent, the rest scan cancellation criteria were applied in a similar fashion to the 13.5% patients who actually underwent stress-only protocols. ...
Aims:
Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) stress-only protocols reduce radiation exposure and cost but require clinicians to make immediate decisions regarding rest scan cancellation. We developed a machine learning (ML) approach for automatic rest scan cancellation and evaluated its prognostic safety.
Methods and results :
In total, 20 414 patients from a solid-state SPECT MPI international multicentre registry with clinical data and follow-up for major adverse cardiac events (MACE) were used to train ML for MACE prediction as a continuous probability (ML score), using 10-fold repeated hold-out testing to separate test from training data. Three ML score thresholds (ML1, ML2, and ML3) were derived by matching the cancellation rates achieved by physician interpretation and two clinical selection rules. Annual MACE rates were compared in patients selected for rest scan cancellation between approaches. Patients selected for rest scan cancellation with ML had lower annualized MACE rates than those selected by physician interpretation or clinical selection rules (ML1 vs. physician interpretation: 1.4 ± 0.1% vs. 2.1 ± 0.1%; ML2 vs. clinical selection: 1.5 ± 0.1% vs. 2.0 ± 0.1%; ML3 vs. stringent clinical selection: 0.6 ± 0.1% vs. 1.7 ± 0.1%, all P < 0.0001) at matched cancellation rates (60 ± 0.7, 64 ± 0.7, and 30 ± 0.6%). Annualized all-cause mortality rates in populations recommended for rest cancellation by physician interpretation, clinical selection approaches were higher (1.3%, 1.2%, and 1.0%, respectively) compared with corresponding ML thresholds (0.6%, 0.6%, and 0.2%).
Conclusion:
ML, using clinical and stress imaging data, can be used to automatically recommend cancellation of rest SPECT MPI scans, while ensuring higher prognostic safety than current clinical approaches.
... Specifically, stressfirst imaging has been shown to reduce radiation exposure to patients by 25% to 80% (16,17), and technologists and nurses by 40% to 50% (18). As the current radiation reduction goal of ASNC is to reduce median doses to <9 mSv (9), and a combination of stress-only imaging with CZT cameras is shown to achieve radiation reduction to 1 mSv (19,20), such protocols will assist in minimizing patient harm and meeting these goals (21). By minimizing the need for rest imaging, this would potentially reduce cost and allow for increased patient throughput as well (16,17). ...
Objectives
This study sought to develop a clinical model that identifies a lower-risk population for coronary artery disease that could benefit from stress-first myocardial perfusion imaging (MPI) protocols and that can be used at point of care to risk stratify patients.
Background
There is an increasing interest in stress-first and stress-only imaging to reduce patient radiation exposure and improve patient workflow and experience.
Methods
A secondary analysis was conducted on a single-center cohort of patients undergoing single-photon emission computed tomography (SPECT) and positron emission tomography (PET) studies. Normal MPI was defined by the absence of perfusion abnormalities and other ischemic markers and the presence of normal left ventricular wall motion and left ventricular ejection fraction. A model was derived using a cohort of 18,389 consecutive patients who underwent SPECT and was validated in a separate cohort of patients who underwent SPECT (n = 5,819), 1 internal cohort of patients who underwent PET (n=4,631), and 1 external PET cohort (n = 7,028).
Results
Final models were made for men and women and consisted of 9 variables including age, smoking, hypertension, diabetes, dyslipidemia, typical angina, prior percutaneous coronary intervention, prior coronary artery bypass graft, and prior myocardial infarction. Patients with a score ≤1 were stratified as low risk. The model was robust with areas under the curve of 0.684 (95% confidence interval [CI]: 0.674 to 0.694) and 0.681 (95% CI: 0.666 to 0.696) in the derivation cohort, 0.745 (95% CI: 0.728 to 0.762) and 0.701 (95% CI: 0.673 to 0.728) in the SPECT validation cohort, 0.672 (95% CI: 0.649 to 0.696) and 0.686 (95% CI: 0.663 to 0.710) in the internal PET validation cohort, and 0.756 (95% CI: 0.740 to 0.772) and 0.737 (95% CI: 0.716 to 0.757) in the external PET validation cohort in men and women, respectively. Men and women who scored ≤1 had negative likelihood ratios of 0.48 and 0.52, respectively.
Conclusions
A novel model, based on easily obtained clinical variables, is proposed to identify patients with low probability of having abnormal MPI results. This point-of-care tool may be used to identify a population that might qualify for stress-first MPI protocols.
... The image quality for very low-dose rest scans (mean effective dose, 1.15 mSv) was superior to conventional SPECT imaging (mean effective dose, 2.39 mSv) (23). Einstein et al. reported stress-only imaging in 69 patients with a mean effective radiation dose of 0.99 mSv (24). In a study of 284 patients undergoing SPECT MPI, Sharir et al. demonstrated similar diagnostic accuracy with low-dose imaging compared with standard dose imaging, but with 50% radiation reduction (25). ...
There has been an evolutionary leap in single photon emission computed tomography (SPECT) imaging with the advent of camera systems which utilize solid-state crystals and novel collimator designs configured specifically for cardiac imaging. Solid-state SPECT camera systems have facilitated dramatic reductions in both imaging time and radiation dose, while maintaining high diagnostic accuracy. These advances are due to simultaneous improvement in photon sensitivity due to the collimator and imaging geometry as well as image resolution due to the improved energy resolution of the new crystals. Improved photon sensitivity has facilitated fast or low dose myocardial perfusion imaging and early dynamic imaging has emerged as a technique for assessing myocardial blood flow with SPECT. Lastly, general purpose solid-state camera systems and hybrid SPECT/CT systems have also been developed which may have important clinical roles in cardiac imaging. This review, summarizes state-of-art solid-state SPECT myocardial perfusion imaging (MPI) technology and clinical applications, including emerging techniques for SPECT MPI flow estimation. We also discuss imaging protocols used with the new cameras, potential imaging pitfalls and review the latest data providing large scale validation of the diagnostic and prognostic value of this new technology.
... A stress-first MPI protocol was used to significantly reduce radiation. (19) (20) Tc-99m sestamibi was injected either at peak treadmill exercise, dobutamine or adenosine stress. (21) (22) MPI imaging was performed with GE Millennium MPR gamma camera. ...
Aims: Cardiovascular disease is the leading cause of death in Jamaica. The aim of this study was to recognize the independent predictors of coronary artery disease (CAD) detected by stress myocar- dial perfusion imaging (MPI), and identify the predictive ability of MPI in detecting significant CAD in a Caribbean population who were referred to a cardiology clinic in Jamaica.
Methods: Retrospective analysis of a cohort of 202 patients who had a stress MPI from 2015-2016. Ninety-one patients underwent symptom-limited treadmill stress MPI, one hundred and nine pa- tients had dobutamine stress MPI and two patients had adenosine stress test.
Results: Exercise stress testing showed a significantly higher hemodynamic response compared to dobutamine stress test (p 0.00034), though there was no significant correlation between the type of stress and test results (p 0.077). Logistic regression model demonstrated that age (odds ratio 1.043; p=0.08), male gender (odds ratio, 0.34; P = .006) and history of hypertension (odds ratio, 0.046 p value 0.0001) were significant independent predictors of a positive MPI. Twenty one patients with abnormal MPI had invasive coronary angiography. The predictive ability of abnormal vascular territory perfusion to correlate with assigned coronary artery was 64.3%, while the predic- tive ability of abnormal MPI to detect CAD was 95.2%.
Conclusion: The prevalence of abnormal myocardial perfusion findings is relatively greater in el- derly, male and hypertensive Caribbean patients with high probability of significant CAD. There- fore, MPI scan may be advocated in assessment workup of patients with presumed greater prob- ability of CAD.
... Use of stress imaging can be performed rapidly and increasingly through protocol optimization, with lower radiation doses [42]. Patients who undergo SPECT imaging have outcomes similar to CCTA in terms of outcomes [25,43]. ...
Chronic chest pain (CCP) of a cardiac etiology is a common clinical problem. The diagnosis and classification of the case of chest pain has rapidly evolved providing the clinician with multiple cardiac imaging strategies. Though scintigraphy and rest echocardiography remain as appropriate imaging tools in the diagnostic evaluation, new technology is available. Current evidence supports the use of alternative imaging tests such as coronary computed tomography angiography (CCTA), cardiac MRI (CMRI), or Rb-82 PET/CT. Since multiple imaging modalities are available to the clinician, the most appropriate noninvasive imaging strategy will be based upon the patient’s clinical presentation and clinical status.
The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.
