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1.
medRxiv ; 2024 Feb 03.
Article in English | MEDLINE | ID: mdl-38352354

ABSTRACT

Background: Fluorodeoxyglucose positron emission tomography (FDG PET) with glycolytic metabolism suppression plays a pivotal role in diagnosing cardiac sarcoidosis. Reorientation of images to match perfusion datasets is critical and myocardial segmentation enables consistent image scaling and quantification. However, both are challenging and labor intensive. We developed a 3D U-Net deep learning (DL) algorithm for automated myocardial segmentation in cardiac sarcoidosis FDG PET. Methods: The DL model was trained on 316 patients' FDG PET scans, and left ventricular contours derived from perfusion datasets. Qualitative analysis of clinical readability was performed to compare DL segmentation with the current automated method on a 50-patient test subset. Additionally, left ventricle displacement and angulation, as well as SUVmax sampling were compared to inter-user reproducibility results. Results: DL segmentation enhanced readability scores in over 90% of cases compared to the standard segmentation currently used in the software. DL segmentation performed similarly to a trained technologist, surpassing standard segmentation for left ventricle displacement and angulation, as well as correlation of SUVmax. Conclusion: The DL-based automated segmentation tool presents a marked improvement in the processing of cardiac sarcoidosis FDG PET, promising enhanced clinical workflow. This tool holds significant potential for accelerating clinical practice and improving consistency and quality. Further research with varied datasets is warranted to broaden its applicability.

2.
medRxiv ; 2023 Oct 25.
Article in English | MEDLINE | ID: mdl-37961713

ABSTRACT

Impaired microvascular and vasomotor function is a common consequence of aging, diabetes, and other risk factors, and is associated with adverse cardiac outcomes. Such impairments are not readily identified by standard clinical methods of cardiovascular testing such as coronary angiography and noninvasive single photon emission tomography (SPECT) myocardial perfusion imaging (MPI). We hypothesized that signals embedded within stress electrocardiograms (ECGs) identify individuals with microvascular and vasomotor dysfunction. Methods: We developed and validated a novel convolutional neural network (CNN) using stress and rest ECG data (ECG-Flow) to identify patients with impaired myocardial flow reserve (MFR) on quantitative positron emission tomography (PET) MPI (N=3887). Diagnostic accuracy was validated with an internal holdout set of patients undergoing stress PET MPI (N=963). The prognostic association of ECG-Flow with mortality was then evaluated in a separate cohort of patients undergoing SPECT MPI (N=5102). Results: ECG-Flow achieved good diagnostic accuracy for impaired MFR in the holdout PET cohort (AUC, sensitivity, specificity: 0.737, 71.1%, 65.7%). Abnormal ECG-Flow was found to be significantly associated with mortality in both PET holdout and SPECT MPI cohorts (adjusted HR 2.12 [95 ρ CI 1.45, 2.10], ρ = 0.0001, and 2.07 [1.82, 2.36], ρ < 0.0001, respectively). Conclusion: Signals predictive of microvascular and vasomotor dysfunction are embedded in stress ECG waveforms. These signals can be identified by deep learning methods and are related to prognosis in patients undergoing both stress PET and SPECT MPI.

3.
Eur J Nucl Med Mol Imaging ; 51(1): 123-135, 2023 12.
Article in English | MEDLINE | ID: mdl-37787848

ABSTRACT

BACKGROUND AND AIMS: Although treatment of ischemia-causing epicardial stenoses may improve symptoms of ischemia, current evidence does not suggest that revascularization improves survival. Conventional myocardial ischemia imaging does not uniquely identify diffuse atherosclerosis, microvascular dysfunction, or nonobstructive epicardial stenoses. We sought to evaluate the prognostic value of integrated myocardial flow reserve (iMFR), a novel noninvasive approach to distinguish the perfusion impact of focal atherosclerosis from diffuse coronary disease. METHODS: This study analyzed a large single-center registry of consecutive patients clinically referred for rest-stress myocardial perfusion positron emission tomography. Cox proportional hazards modeling was used to assess the association of two previously reported and two novel perfusion measures with mortality risk: global stress myocardial blood flow (MBF); global myocardial flow reserve (MFR); and two metrics derived from iMFR analysis: the extents of focal and diffusely impaired perfusion. RESULTS: In total, 6867 patients were included with a median follow-up of 3.4 years [1st-3rd quartiles, 1.9-5.0] and 1444 deaths (21%). Although all evaluated perfusion measures were independently associated with death, diffusely impaired perfusion extent (hazard ratio 2.65, 95%C.I. [2.37-2.97]) and global MFR (HR 2.29, 95%C.I. [2.08-2.52]) were consistently stronger predictors than stress MBF (HR 1.62, 95%C.I. [1.46-1.79]). Focally impaired perfusion extent (HR 1.09, 95%C.I. [1.03-1.16]) was only moderately related to mortality. Diffusely impaired perfusion extent remained a significant independent predictor of death when combined with global MFR (p < 0.0001), providing improved risk stratification (overall net reclassification improvement 0.246, 95%C.I. [0.183-0.310]). CONCLUSIONS: The extent of diffusely impaired perfusion is a strong independent and additive marker of mortality risk beyond traditional risk factors, standard perfusion imaging, and global MFR, while focally impaired perfusion is only moderately related to mortality.


Subject(s)
Atherosclerosis , Coronary Artery Disease , Fractional Flow Reserve, Myocardial , Myocardial Perfusion Imaging , Humans , Constriction, Pathologic , Coronary Artery Disease/diagnostic imaging , Positron-Emission Tomography , Perfusion , Ischemia , Myocardial Perfusion Imaging/methods , Coronary Circulation
4.
Eur J Nucl Med Mol Imaging ; 51(1): 136-146, 2023 12.
Article in English | MEDLINE | ID: mdl-37807004

ABSTRACT

PURPOSE: Distinguishing obstructive epicardial coronary artery disease (CAD) from microvascular dysfunction and diffuse atherosclerosis would be of immense benefit clinically. However, quantitative measures of absolute myocardial blood flow (MBF) integrate the effects of focal epicardial stenosis, diffuse atherosclerosis, and microvascular dysfunction. In this study, MFR and relative perfusion quantification were combined to create integrated MFR (iMFR) which was evaluated using data from a large clinical registry and an international multi-center trial and validated against invasive coronary angiography (ICA). METHODS: This study included 1,044 clinical patients referred for 82Rb rest/stress positron emission tomography myocardial perfusion imaging and ICA, along with 231 patients from the Flurpiridaz 301 trial (clinicaltrials.gov NCT01347710). MFR and relative perfusion quantification were combined to create an iMFR map. The incremental value of iMFR was evaluated for diagnosis of obstructive stenosis, adjusted for patient demographics and pre-test probability of CAD. Models for high-risk anatomy (left main or three-vessel disease) were also constructed. RESULTS: iMFR parameters of focally impaired perfusion resulted in best fitting diagnostic models. Receiver-operating characteristic analysis showed a slight improvement compared to standard quantitative perfusion approaches (AUC 0.824 vs. 0.809). Focally impaired perfusion was also associated with high-risk CAD anatomy (OR 1.40 for extent, and OR 2.40 for decreasing mean MFR). Diffusely impaired perfusion was associated with lower likelihood of obstructive CAD, and, in the absence of transient ischemic dilation (TID), with lower likelihood of high-risk CAD anatomy. CONCLUSIONS: Focally impaired perfusion extent derived from iMFR assessment is a powerful incremental predictor of obstructive CAD while diffusely impaired perfusion extent can help rule out obstructive and high-risk CAD in the absence of TID.


Subject(s)
Atherosclerosis , Coronary Artery Disease , Fractional Flow Reserve, Myocardial , Myocardial Perfusion Imaging , Humans , Constriction, Pathologic , Coronary Angiography/methods , Coronary Artery Disease/diagnostic imaging , Coronary Circulation , Myocardial Perfusion Imaging/methods , Positron-Emission Tomography/methods , Multicenter Studies as Topic , Clinical Trials as Topic
5.
Eur J Nucl Med Mol Imaging ; 51(1): 147-158, 2023 12.
Article in English | MEDLINE | ID: mdl-37721579

ABSTRACT

PURPOSE: To establish requirements for normal databases for quantitative rubidium-82 (82Rb) PET MPI analysis with contemporary 3D PET/CT technology and reconstruction methods for maximizing diagnostic accuracy of total perfusion deficit (TPD), a combined metric of defect extent and severity, versus invasive coronary angiography. METHODS: In total, 1571 patients with 82Rb PET/CT MPI on a 3D scanner and stress static images reconstructed with and without time-of-flight (TOF) modeling were identified. An additional eighty low pre-test probability of disease (PTP) patients reported as normal were used to form separate sex-stratified and sex-independent iterative and TOF normal databases. 3D normal databases were applied to matched patient reconstructions to quantify TPD. Per-patient and per-vessel performance of 3D versus 2D PET normal databases was assessed with receiver operator characteristic curve analysis. Diagnostic accuracy was evaluated at optimal thresholds established from PTP patients. Results were compared against logistic regression modeling of TPD adjusted for clinical variables, and standard clinical interpretation. RESULTS: TPD diagnostic accuracy was significantly higher using 3D PET normal databases (per-patient: 80.1% for 3D databases, versus 74.9% and 77.7% for 2D database applied to iterative and TOF images respectively, p < 0.05). Differences in male and female normal distributions for 3D attenuation-corrected reconstructions were not clinically meaningful; therefore, sex-independent databases were used. Logistic regression modeling including TPD demonstrated improved performance over clinical reads. CONCLUSIONS: Normal databases tailored to 3D PET images provide significantly improved diagnostic accuracy for PET MPI evaluation with automated quantitative TPD. Clinical application of these techniques should be considered to support accurate image interpretation.


Subject(s)
Coronary Artery Disease , Myocardial Perfusion Imaging , Humans , Male , Female , Coronary Artery Disease/diagnostic imaging , Positron Emission Tomography Computed Tomography , Myocardial Perfusion Imaging/methods , Sensitivity and Specificity , Coronary Angiography , Tomography, Emission-Computed, Single-Photon/methods
6.
Eur J Nucl Med Mol Imaging ; 50(4): 1028-1033, 2023 03.
Article in English | MEDLINE | ID: mdl-36401636

ABSTRACT

PURPOSE: Although SPECT myocardial perfusion imaging (MPI) is susceptible to artifacts from soft tissue attenuation, most scans are performed without attenuation correction. Deep learning-based attenuation corrected (DLAC) polar maps improved diagnostic accuracy for detection of coronary artery disease (CAD) beyond non-attenuation-corrected (NAC) polar maps in a large single center study. However, the generalizability of this approach to other institutions with different scanner models and protocols is uncertain. In this study, we evaluated the diagnostic performance of DLAC compared to NAC for detection of CAD as defined by invasive coronary angiography (ICA) in a large multi-center trial. METHODS: During the phase 3 flurpiridaz multi-center diagnostic clinical trial, conducted over 74 international sites, patients with known or suspected CAD who were referred for a clinically indicated ICA were enrolled. Using receiver operating characteristic (ROC) analysis, we evaluated the detectability of obstructive CAD, defined by quantitative coronary angiography by a core laboratory, using total perfusion deficit (TPD) as an integrated measure of defect extent and severity on DLAC polar maps compared to NAC polar maps. This was also compared against the visual scoring of three expert core lab readers. RESULTS: Out of 755 patients, 722 (69% male) had evaluable SPECT and ICA for this study. ROC analysis demonstrated significant improvement in detecting per-patient obstructive CAD with DLAC over NAC with area under the curve (AUC) of 0.752 (95% CI: 0.711-0.792) for DLAC compared to 0.717 (0.675-0.759) for NAC (p value = 0.016). Compared to the consensus of expert readers AUC = 0.743 (0.701-0.784), DLAC was comparable (p value = 0.913), whereas NAC underperformed (p value = 0.051). CONCLUSION: DL-based attenuation correction improves diagnostic performance of SPECT MPI for detecting CAD in data from a large multi-center clinical trial regardless of SPECT camera model or protocol. TRIAL REGISTRATION: A Phase 3 Multi-center Study to Assess PET Imaging of Flurpiridaz F 18 Injection in Patients With CAD, ClinicalTrials.gov Identifier: NCT01347710, registered on 4 May 2011. https://clinicaltrials.gov/ct2/show/study/NCT01347710.


Subject(s)
Coronary Artery Disease , Deep Learning , Myocardial Perfusion Imaging , Humans , Male , Female , Myocardial Perfusion Imaging/methods , Tomography, Emission-Computed, Single-Photon/methods , Coronary Artery Disease/diagnostic imaging , Coronary Angiography/methods
7.
Eur J Nucl Med Mol Imaging ; 49(9): 3140-3149, 2022 07.
Article in English | MEDLINE | ID: mdl-35312837

ABSTRACT

PURPOSE: Myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT) is widely used for coronary artery disease (CAD) evaluation. Although attenuation correction is recommended to diminish image artifacts and improve diagnostic accuracy, approximately 3/4ths of clinical MPI worldwide remains non-attenuation-corrected (NAC). In this work, we propose a novel deep learning (DL) algorithm to provide "virtual" DL attenuation-corrected (DLAC) perfusion polar maps solely from NAC data without concurrent computed tomography (CT) imaging or additional scans. METHODS: SPECT MPI studies (N = 11,532) with paired NAC and CTAC images were retrospectively identified. A convolutional neural network-based DL algorithm was developed and trained on half of the population to predict DLAC polar maps from NAC polar maps. Total perfusion deficit (TPD) was evaluated for all polar maps. TPDs from NAC and DLAC polar maps were compared to CTAC TPDs in linear regression analysis. Moreover, receiver-operating characteristic analysis was performed on NAC, CTAC, and DLAC TPDs to predict obstructive CAD as diagnosed from invasive coronary angiography. RESULTS: DLAC TPDs exhibited significantly improved linear correlation (p < 0.001) with CTAC (R2 = 0.85) compared to NAC vs. CTAC (R2 = 0.68). The diagnostic performance of TPD was also improved with DLAC compared to NAC with an area under the curve (AUC) of 0.827 vs. 0.780 (p = 0.012) with no statistically significant difference between AUC for CTAC and DLAC. At 88% sensitivity, specificity was improved by 18.9% for DLAC and 25.6% for CTAC. CONCLUSIONS: The proposed DL algorithm provided attenuation correction comparable to CTAC without the need for additional scans. Compared to conventional NAC perfusion imaging, DLAC significantly improved diagnostic accuracy.


Subject(s)
Coronary Artery Disease , Deep Learning , Myocardial Perfusion Imaging , Coronary Artery Disease/diagnostic imaging , Humans , Image Processing, Computer-Assisted/methods , Myocardial Perfusion Imaging/methods , Perfusion , Retrospective Studies , Tomography, Emission-Computed, Single-Photon
8.
J Nucl Cardiol ; 29(5): 2612-2623, 2022 Oct.
Article in English | MEDLINE | ID: mdl-34448094

ABSTRACT

BACKGROUND: As clinical use of myocardial blood flow (MBF) increases, dynamic series are becoming part of the typical workflow. The methods and parameters used to reconstruct these series require investigation to ensure accurate quantification. METHODS: Fifty-nine rest/stress dynamic 82Rb PET studies, acquired on a Biograph mCT, from a combination of normal volunteers and low-likelihood patients were reconstructed with and without time of flight (TOF) for varying iterations and processed to obtain relative perfusion and MBF polar maps. Regional values from mean polar maps were fit to a linear mixed-effect model to quantify convergence and select the optimal number of iterations. RESULTS: TOF reconstructions converged faster and yielded more uniform relative perfusion polar maps. However, the stress MBF distribution for TOF reconstructions was more heterogeneous, with a higher-intensity septal wall. This phenomenon requires further investigation, with right ventricle blood pool spillover possibly having an effect. Optimal reconstructions were defined as 5-iteration non-TOF (24-subset) reconstructions and 3-iteration TOF (21-subset) reconstructions. CONCLUSION: Optimal cardiac reconstructions were identified for non-TOF and TOF reconstructions of dynamic series. TOF reconstruction presents as the more accurate method, given the more uniform relative perfusion distribution.


Subject(s)
Myocardial Perfusion Imaging , Positron-Emission Tomography , Coronary Circulation , Humans , Myocardial Perfusion Imaging/methods , Normal Distribution , Perfusion , Positron-Emission Tomography/methods
9.
J Nucl Cardiol ; 29(5): 2078-2089, 2022 Oct.
Article in English | MEDLINE | ID: mdl-34426935

ABSTRACT

BACKGROUND: PET myocardial flow reserve (MFR) has established diagnostic and prognostic value. Technological advances have now enabled SPECT MFR quantification. We investigated whether SPECT MFR precision is sufficient for clinical categorization of patients. METHODS: Validation studies vs invasive flow measurements and PET MFR were reviewed to determine global SPECT MFR thresholds. Studies vs PET and a SPECT MFR repeatability study were used to establish imprecision in SPECT MFR measurements as the standard deviation of the difference between SPECT and PET MFR, or test-retest SPECT MFR. Simulations were used to evaluate the impact of SPECT MFR imprecision on confidence of clinically relevant categorization. RESULTS: Based on validation studies, the typical PET MFR categories were used for SPECT MFR classification (< 1.5, 1.5-2.0, > 2.0). Imprecision vs PET MFR ranged from 0.556 to 0.829, and test-retest imprecision was 0.781-0.878. Simulations showed correct classification of up to only 34% of patients when 1.5 ≤ true MFR ≤ 2.0. Categorization with high confidence (> 80%) was only achieved for extreme MFR values (< 1.0 or > 2.5), with correct classification in only 15% of patients in a typical lab with MFR of 1.8 ± 0.5. CONCLUSIONS: Current SPECT-derived estimates of MFR lack precision and require further optimization for clinical risk stratification.


Subject(s)
Coronary Artery Disease , Fractional Flow Reserve, Myocardial , Myocardial Perfusion Imaging , Coronary Circulation , Humans , Myocardial Perfusion Imaging/methods , Myocardium , Positron-Emission Tomography/methods , Tomography, Emission-Computed, Single-Photon/methods
10.
J Nucl Cardiol ; 29(2): 413-425, 2022 04.
Article in English | MEDLINE | ID: mdl-34341953

ABSTRACT

BACKGROUND: In ischemic cardiomyopathy patients, cardiac sympathetic nervous system dysfunction is a predictor of sudden cardiac arrest (SCA). This study compared abnormal innervation and perfusion measured by [11C]meta-hydroxyephedrine (HED) vs [13N]ammonia (NH3), conventional uptake vs parametric tracer analysis, and their SCA risk discrimination. METHODS: This is a sub-study analysis of the prospective PAREPET trial, which followed ischemic cardiomyopathy patients with reduced left ventricular ejection fraction (LVEF ≤ 35%) for events of SCA. Using n = 174 paired dynamic HED and NH3 positron emission tomography (PET) scans, regional defect scores (%LV extent × severity) were calculated using HED and NH3 uptake, as well as HED distribution volume and NH3 myocardial blood flow by kinetic modeling. RESULTS: During 4.1 years follow-up, there were 27 SCA events. HED defects were larger than NH3, especially in the lowest tertile of perfusion abnormality (P < .001). Parametric defects were larger than their respective tracer uptake defects (P < .001). SCA risk discrimination was not significantly improved with parametric or uptake mismatch (AUC = 0.73 or 0.70) compared to HED uptake defect scores (AUC = 0.67). CONCLUSION: Quantification of HED distribution volume and NH3 myocardial blood flow produced larger defects than their respective measures of tracer uptake, but did not lead to improved SCA risk stratification vs HED uptake alone.


Subject(s)
Cardiomyopathies , Myocardial Ischemia , Ammonia , Cardiomyopathies/diagnostic imaging , Death, Sudden, Cardiac , Ephedrine/analogs & derivatives , Heart/innervation , Humans , Kinetics , Myocardial Ischemia/diagnostic imaging , Positron-Emission Tomography , Prospective Studies , Risk Assessment , Stroke Volume , Sympathetic Nervous System , Ventricular Function, Left
11.
J Nucl Cardiol ; 29(5): 2262-2270, 2022 Oct.
Article in English | MEDLINE | ID: mdl-34780036

ABSTRACT

BACKGROUND: 13N-ammonia and 18F-flurpiridaz require longer delays between rest and stress studies to allow for decay, lowering clinical throughput. In this study, we investigated the impact of residual subtraction on MBF and MFR estimates, as well as its effects on diagnostic accuracy. METHODS: We retrospectively analyzed 63 patients who underwent a dynamic ammonia rest/stress study and 231 patients from the flurpiridaz 301 trial. Residual subtraction was performed by subtracting the mean pre-injection activity in each sampled region from that region's time activity curve. Corrected and uncorrected MBF and MFR were analyzed. Diagnostic accuracy was compared to quantitative coronary angiograms (QCA) for the flurpiridaz population. RESULTS: With delays between injections above 3 half-lives, and a doubled stress dose, residual activity did not meaningfully increase ammonia MBF (< 5%). For shorter injection delays, stress MBF was overestimated by 13.6% ± 5.0% (P < .001). Residual activity had a large effect on flurpiridaz stress MBF, overestimating it by 37.9% ± 23.2% (P < .001). Comparison to QCA showed a significant improvement in AUC with residual subtraction (from 0.748 to 0.831, P = .001). MFR yielded similar results. CONCLUSIONS: Accounting for residual activity has a marked impact on stress MBF and MFR and improves diagnostic accuracy relative to QCA.


Subject(s)
Coronary Artery Disease , Fractional Flow Reserve, Myocardial , Myocardial Perfusion Imaging , Ammonia , Clinical Trials as Topic , Coronary Artery Disease/diagnostic imaging , Coronary Circulation/physiology , Humans , Myocardial Perfusion Imaging/methods , Positron-Emission Tomography/methods , Retrospective Studies
13.
Eur J Nucl Med Mol Imaging ; 48(12): 3835-3846, 2021 11.
Article in English | MEDLINE | ID: mdl-33982174

ABSTRACT

PURPOSE: Clinical measurement of myocardial blood flow (MBF) has emerged as an important component of routine PET-CT assessment of myocardial perfusion in patients with known or suspected coronary artery disease. Although multiple society guidelines recommend patient-specific dosing, there is a lack of studies evaluating the efficacy of patient-specific dosing for quantitative MBF accuracy. METHODS: Two patient-specific dosing protocols (weight- and BMI-adjusted) were retrospectively evaluated in 435 consecutive clinical patients referred for PET myocardial perfusion assessment. MBF was estimated at rest and after regadenoson-induced hyperemia. The effect of dosing protocol on dose reduction, PET scanner saturation, relative perfusion, and image quality was compared. The effect of PET saturation on the accuracy of MBF and myocardial flow reserve (MFR) in remote myocardium was assessed with multivariable linear regression. RESULTS: BMI-adjusted dosing was associated with lower administered 82Rb activities (1036.0 ± 274 vs. 1147 ± 274 MBq, p = 0.003) and lower PET scanner saturation incidence (28 vs. 38%, p = 0.006) and severity (median saturation severity index 0.219 ± 0.33 vs. 0.397 ± 0.59%, p = 0.018) compared to weight-adjusted dosing. PET saturation that occurred with either dosing protocol was moderate and resulted in modest remote MBF and MFR biases ranging from 2 to 9% after adjusting for patient age, sex, BMI, rate-pressure product, and LV ejection fraction. No adverse effects of BMI dose adjustment were observed in relative perfusion assessment or image quality. CONCLUSIONS: Patient-specific dosing according to BMI is an effective method for guideline-directed dose reduction while maintaining image quality and accuracy for routine MBF and MFR quantification.


Subject(s)
Coronary Artery Disease , Myocardial Perfusion Imaging , Coronary Artery Disease/diagnostic imaging , Coronary Circulation , Humans , Positron Emission Tomography Computed Tomography , Positron-Emission Tomography , Retrospective Studies , Tomography, X-Ray Computed
14.
J Nucl Cardiol ; 28(3): 835-850, 2021 06.
Article in English | MEDLINE | ID: mdl-33389638

ABSTRACT

BACKGROUND: Myocardial flow reserve (MFR) measurement provides incremental diagnostic and prognostic information. The objective of the current study was to investigate the application of a simplified model for the estimation of MFR using only the stress/rest myocardial activity ratio (MAR) in patients undergoing rest-stress cardiac PET MPI. METHODS AND RESULTS: Rest and dipyridamole stress dynamic PET imaging was performed in consecutive patients using 82Rb or 13NH3 (n = 250 each). Reference standard MFR was quantified using a standard one-tissue compartment model. Stress/rest myocardial activity ratio (MAR) was calculated using the LV-mean activity from 2 to 6 minutes post-injection. Simplified estimates of MFR (MFREST) were then calculated using an inverse power function. For 13NH3, there was good correlation between MFR and MFREST values (R = 0.63), with similar results for 82Rb (R = 0.73). There was no bias in the MFREST values with either tracer. The overall diagnostic performance of MFREST for detection of MFR < 2 was good with ROC area under the curve (AUC) = 83.2 ± 1.2% for 13NH3 and AUC = 90.4 ± 0.7% for 82Rb. CONCLUSION: MFR was estimated with good accuracy using 82Rb and 13NH3 with a simplified method that relies only on stress/rest activity ratios. This novel approach does not require dynamic imaging or tracer kinetic modeling. It may be useful for routine quality assurance of PET MFR measurements, or in scanners where full dynamic imaging and tracer kinetic modeling is not feasible for technical or logistical reasons.


Subject(s)
Ammonia , Coronary Artery Disease/diagnostic imaging , Fractional Flow Reserve, Myocardial , Myocardial Perfusion Imaging/methods , Nitrogen Radioisotopes , Positron-Emission Tomography/methods , Rubidium Radioisotopes , Aged , Area Under Curve , Exercise Test , Female , Hemodynamics , Humans , Image Processing, Computer-Assisted , Imaging, Three-Dimensional , Kinetics , Male , Middle Aged , Positron Emission Tomography Computed Tomography , Pressure , Prognosis , ROC Curve , Reproducibility of Results , Retrospective Studies , Stress, Mechanical , Tomography, Emission-Computed, Single-Photon
15.
J Nucl Cardiol ; 28(1): 225-233, 2021 02.
Article in English | MEDLINE | ID: mdl-30834500

ABSTRACT

BACKGROUND: In addition to acquired photon counts, image noise depends on the image reconstruction algorithm. This work develops patient-specific activity or acquisition time protocols to standardize the average noise in a reconstructed image for different patients, cameras, and reconstruction algorithms. METHODS: Image noise was calculated for images from 43 patients acquired on both a conventional and a multiple-pinhole cardiac SPECT camera. Functions were found to relate image noise to radiotracer activity, scan time, and body mass and were validated by normalizing the image noise in a test set of 58 patients. RESULTS: There was a 3.6-fold difference in photon sensitivity between the two cameras but a 16-fold difference in activity-scan time was necessary to match the noise levels. Image noise doubled from 45 to 128 kg for the conventional camera (12.8 minutes) and tripled for the multiple-pinhole camera (5 minutes) for 350 MBq (9.5 mCi) 99mTc-tetrofosmin. It was 16.3% and 6.1% respectively for an average sized patient. CONCLUSIONS: A linear scaling of activity with respect to the patient weight normalizes image noise but the scaling factors depend on the choice of camera and image reconstruction parameters. Therefore, equivalent numbers of acquired photon counts are not sufficient to guarantee equivalent image noise.


Subject(s)
Gamma Cameras , Heart/diagnostic imaging , Image Processing, Computer-Assisted , Myocardial Perfusion Imaging , Tomography, Emission-Computed, Single-Photon , Adult , Aged , Aged, 80 and over , Algorithms , Artifacts , Body Weight , Clinical Protocols , Female , Humans , Male , Middle Aged , Radiopharmaceuticals , Reference Values , Retrospective Studies , Sensitivity and Specificity , Time Factors
16.
J Nucl Cardiol ; 28(6): 2712-2725, 2021 12.
Article in English | MEDLINE | ID: mdl-32185684

ABSTRACT

BACKGROUND: Qualification and interpretation standards are essential for establishing 99mTc-SPECT MPI accuracy vs. alternative modalities. METHODS: Rest-stress 99mTc-SPECT phantom scans were acquired on 35 cameras. LV defects were quantified with summed stress (SSS) and difference scores (SDS) at 2 core labs. SDS ≥ 2 in the right coronary artery (RCA) was the qualifying standard. Twenty rest (R)-stress (S) patient images were acquired on qualified cameras and interpreted by core labs. Global scoring differences > 3 between labs or discordant clinical interpretations underwent review. Scoring, interpretation, image quality, and diagnostic parameter agreement were assessed. RESULTS: Phantom scans: visual scoring confirmed RCA-ischemia on all cameras. Regional SSS, SDS agreement was moderate to very good: ICC-r = 0.57, 0.84. Patient scans: 90% of global SSS, 85% of SDS differences were ≤ 3. Regional SSS, SDS agreement: ICC-r = 0.87, 0.86, and global abnormal (SSS ≥ 4) and ischemic (SDS ≥ 2) interpretation: ICC-r = 0.90 were excellent. Clinical interpretation agreement was 100% following review. Image quality agreement was 70%. Automated metrics also agreed: ischemic total perfusion deficit ICC-r = 0.75, reversible perfusion defect, transient ischemic dilation, and S-R LV ejection fraction ICC-r ≥ 0.90. CONCLUSION: Quantitative scoring and interpretation of scans were highly repeatable with site qualification and clinical interpretation standardization, indicating that dual-core lab interpretation is appropriate to determine 99mTc-SPECT MPI accuracy.


Subject(s)
Myocardial Perfusion Imaging/methods , Phantoms, Imaging , Technetium , Tomography, Emission-Computed, Single-Photon/standards , Aged , Aged, 80 and over , Canada , Female , Humans , Male , Middle Aged
17.
J Nucl Cardiol ; 28(6): 2745-2757, 2021 12.
Article in English | MEDLINE | ID: mdl-32347526

ABSTRACT

BACKGROUND: Regional cardiac sympathetic denervation is predictive of sudden cardiac arrest in patients with ischemic cardiomyopathy. The reproducibility of denervation scores between automated software programs has not been evaluated. This study seeks to (1) compare the inter-rater reliability of regional denervation measurements using two analysis programs: FlowQuant® and Corridor4DM®; (2) evaluate test-retest repeatability of regional denervation scores. METHODS: N = 190 dynamic [11C]meta-hydroxyephedrine (HED) PET scans were reviewed from the PAREPET trial in ischemic cardiomyopathy patients with reduced left ventricular ejection fraction(LVEF ≤ 35%). N = 12 scans were excluded due to non-diagnostic quality. N = 178 scans were analyzed using FlowQuant and Corridor4DM software, each by two observers. Test-retest scans from N = 20 patients with stable heart failure were utilized for test-retest analysis. Denervation scores were defined as extent × severity of relative uptake defects in LV regions with < 75% of maximal uptake. Results were evaluated using intraclass correlation coefficient (ICC) and Bland-Altman coefficient of repeatability (RPC). RESULTS: Inter-observer, inter-software, and test-retest ICC values were excellent (ICC = 94% to 99%) and measurement variability was small (RPC < 11%). Mean differences between observers ranged .2% to 1.1% for Corridor4DM (P = .28), FlowQuant (P < .001), and between software programs (P < .001). Kaplan-Meier analysis demonstrated HED scores from both programs were predictive of SCA. CONCLUSION: Inter-rater reliability for both analysis programs was excellent and test-retest repeatability was consistent. The minimal difference in scores between FlowQuant and Corridor4DM supports their use in future trials.


Subject(s)
Contrast Media , Heart/innervation , Positron-Emission Tomography , Software , Surgery, Computer-Assisted , Sympathectomy/methods , Aged , Cardiac Imaging Techniques , Ephedrine/analogs & derivatives , Female , Humans , Male , Middle Aged , Observer Variation , Reproducibility of Results , Retrospective Studies
18.
J Nucl Cardiol ; 28(6): 2784-2795, 2021 12.
Article in English | MEDLINE | ID: mdl-32383088

ABSTRACT

BACKGROUND: Reduced left ventricular (LV) function is associated with increased myocardial oxygen consumption rate (MVO2) and altered sympathetic activity, the role of which is not well described in right ventricular (RV) dysfunction. METHODS AND RESULTS: 33 patients with left heart failure were assessed for RV function/size using echocardiography. Positron emission tomography (PET) was used to measure 11C-acetate clearance rate (kmono), 11C-hydroxyephedrine (11C-HED) standardized uptake value (SUV), and retention rate. RV MVO2 was estimated from kmono. 11C-HED SUV and retention indicated sympathetic neuronal function. A composite clinical endpoint was defined as unplanned cardiac hospitalization within 5 years. Patients with (n = 10) or without (n = 23) RV dysfunction were comparable in terms of sex (male: 70.0 vs 69.5%), LV ejection fraction (39.6 ± 9.0 vs 38.6 ± 9.4%), and systemic hypertension (70.0 vs 78.3%). RV dysfunction patients were older (70.9 ± 13.5 vs 59.4 ± 11.5 years; P = .03) and had a higher prevalence of pulmonary hypertension (60.0% vs 13.0%; P = .01). RV dysfunction was associated with increased RV MVO2 (.106 ± .042 vs .068 ± .031 mL/min/g; P = .02) and decreased 11C-HED SUV and retention (6.05 ± .53 vs 7.40 ± 1.39 g/mL (P < .001) and .08 ± .02 vs .11 ± .03 mL/min/g (P < .001), respectively). Patients with an RV MVO2 above the median had a shorter event-free survival (hazard ratio = 5.47; P = .01). Patients who died within the 5-year follow-up period showed a trend (not statistically significant) for higher RV MVO2 (.120 ± .026 vs .074 ± .038 mL/min/g; P = .05). CONCLUSIONS: RV dysfunction is associated with increased oxygen consumption (also characterized by a higher risk for cardiac events) and impaired RV sympathetic function.


Subject(s)
Heart Failure/metabolism , Myocardium/metabolism , Oxygen Consumption , Ventricular Dysfunction, Right/metabolism , Ventricular Remodeling , Aged , Aged, 80 and over , Female , Heart Failure/complications , Heart Failure/physiopathology , Humans , Male , Middle Aged , Progression-Free Survival , Retrospective Studies , Ventricular Dysfunction, Right/complications , Ventricular Dysfunction, Right/physiopathology
19.
J Nucl Med ; 62(2): 168-176, 2021 02.
Article in English | MEDLINE | ID: mdl-33067339

ABSTRACT

Quantitative analysis has been applied extensively to image processing and interpretation in nuclear cardiology to improve disease diagnosis and risk stratification. This is Part 2 of a two-part continuing medical education article, which will review the potential clinical role for emerging quantitative analysis tools. The article will describe advanced methods for quantifying dyssynchrony, ventricular function and perfusion, and hybrid imaging analysis. This article discusses evolving methods to measure myocardial blood flow with positron emission tomography and single-photon emission computed tomography. Novel quantitative assessments of myocardial viability, microcalcification and in patients with cardiac sarcoidosis and cardiac amyloidosis will also be described. Lastly, we will review the potential role for artificial intelligence to improve image analysis, disease diagnosis, and risk prediction. The potential clinical role for all these novel techniques will be highlighted as well as methods to optimize their implementation. (J Nucl Cardiol 2020).


Subject(s)
Cardiology/methods , Nuclear Medicine/methods , Humans , Multimodal Imaging , Single Photon Emission Computed Tomography Computed Tomography , Ventricular Function
20.
J Nucl Cardiol ; 28(1): 115-127, 2021 02.
Article in English | MEDLINE | ID: mdl-33067750

ABSTRACT

Quantitative analysis has been applied extensively to image processing and interpretation in nuclear cardiology to improve disease diagnosis and risk stratification. This is Part 2 of a two-part continuing medical education article, which will review the potential clinical role for emerging quantitative analysis tools. The article will describe advanced methods for quantifying dyssynchrony, ventricular function and perfusion, and hybrid imaging analysis. This article discusses evolving methods to measure myocardial blood flow with positron emission tomography and single-photon emission computed tomography. Novel quantitative assessments of myocardial viability, microcalcification and in patients with cardiac sarcoidosis and cardiac amyloidosis will also be described. Lastly, we will review the potential role for artificial intelligence to improve image analysis, disease diagnosis, and risk prediction. The potential clinical role for all these novel techniques will be highlighted as well as methods to optimize their implementation.


Subject(s)
Heart Diseases/diagnostic imaging , Image Processing, Computer-Assisted , Multimodal Imaging , Myocardial Perfusion Imaging , Humans
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