Automated Deep Learning Segmentation of Cardiac Inflammatory FDG PET.

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.

Self-supervised deep representation learning of a foundation transformer model enabling efficient ECG-based assessment of cardiac and coronary function with limited labels.

Although deep learning methods have shown great promise for identification of structural and functional cardiac abnormalities using electrocardiographic data, these methods are data hungry, posing a challenge for critically important tasks where ground truth labels are relatively scarce. Impaired coronary microvascular and vasomotor function is difficult to identify with standard clinical methods of cardiovascular testing such as coronary angiography and noninvasive single photon emission tomography (SPECT) myocardial perfusion imaging (MPI). Gold standard data from positron emission tomography (PET) are gaining emphasis in clinical guidelines but are expensive and only available in relatively limited centers.

Integrated myocardial flow reserve (iMFR) assessment: diffuse atherosclerosis and microvascular dysfunction are more strongly associated with mortality than focally impaired perfusion.

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.

Improved diagnostic accuracy for coronary artery disease detection with quantitative 3D Rb PET myocardial perfusion imaging.

Purpose: To establish requirements for normal databases for quantitative rubidium-82 (Rb) 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 Rb 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.

"Virtual" attenuation correction: improving stress myocardial perfusion SPECT imaging using deep learning.

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.

The prognostic value of positron emission tomography in the evaluation of suspected cardiac sarcoidosis.

Objectives: To assess the prognostic value of positron emission tomography (PET) imaging in patients undergoing evaluation for known or suspected cardiac sarcoidosis (CS) while not on active immunotherapy.

Background: Previous studies have attempted to identify the value of PET imaging to aid in risk stratification of patients with CS, however, most cohorts have included patients currently on immunosuppression, which may confound scan results by suppressing positive findings.

Methods: We retrospectively analyzed 197 patients not on immunosuppression who underwent F-fluorodeoxyglucose (FDG) PET scans for evaluation of known or suspected CS.

Effect of iterations and time of flight on normal distributions of Rb PET relative perfusion and myocardial blood flow.

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 Rb 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.

Myocardial flow reserve estimation with contemporary CZT-SPECT and Tc-tracers lacks precision for routine clinical application.

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.

Effects of two patient-specific dosing protocols on measurement of myocardial blood flow with 3D Rb cardiac PET.

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.

Left ventricular mass on positron emission tomography: Validation against cardiovascular magnetic resonance.

Background: Left ventricular hypertrophy (LVH) is an important clinical finding that is independently associated with mortality and cardiovascular events. We aimed to assess the interstudy variability of LV mass quantitation between PET and CMR.

Methods: Patients who underwent both PET and CMR within 1 year were identified from prospective institutional registries.

Reducing motion-correction-induced variability in rubidium myocardial blood-flow quantification.

Background: Clinical use of myocardial blood flow (MBF) and flow reserve (MFR) is increasing. Motion correction is necessary to obtain accurate results but can introduce variability when performed manually. We sought to reduce that variability with an automated motion-correction algorithm.

Initial clinical experience of N13-ammonia myocardial perfusion PET/CT using a compact superconducting production system.

Background: Although N13-ammonia has favorable properties among FDA approved radiotracers, complexity of implementation has limited its use. We describe the initial patient experience of N13-ammonia PET imaging using a compact N13-ammonia production system.

Methods: N13 was produced using the ION-12SC, a 12MeV, 10uA superconducting minimally shielded cyclotron, and reduced to N13-ammonia in an automated multi-use purification unit.

The utility of Rb PET for myocardial viability assessment: Comparison with perfusion-metabolism Rb-F-FDG PET.

Background: Rb kinetics may distinguish scar from viable but dysfunctional (hibernating) myocardium. We sought to define the relationship between Rb kinetics and myocardial viability compared with conventional Rb and F-fluorodeoxyglucose (FDG) perfusion-metabolism PET imaging.

Methods: Consecutive patients (N = 120) referred for evaluation of myocardial viability prior to revascularization and normal volunteers (N = 37) were reviewed.

Automated dynamic motion correction using normalized gradient fields for rubidium PET myocardial blood flow quantification.

Background: Patient motion can lead to misalignment of left ventricular (LV) volumes-of-interest (VOIs) and subsequently inaccurate quantification of myocardial blood flow (MBF) and flow reserve (MFR) from dynamic PET myocardial perfusion images. We aimed to develop an image-based 3D-automated motion-correction algorithm that corrects the full dynamic sequence for translational motion, especially in the early blood phase frames (~ first minute) where the injected tracer activity is transitioning from the blood pool to the myocardium and where conventional image registration algorithms have had limited success.

Methods: We studied 225 consecutive patients who underwent dynamic rest/stress rubidium-82 chloride (Rb) PET imaging.