Dataset Information

Consistent tracer administration profile improves test-retest repeatability of myocardial blood flow quantification with ⁸²Rb dynamic PET imaging.

ABSTRACT:

Objectives

Quantification of myocardial blood flow (MBF) and stress/rest flow reserve is used increasingly to diagnose multi-vessel coronary artery disease and micro-vascular disease with PET imaging. However, variability in the measurements may limit physician confidence to direct revascularization therapies based on specific threshold values. This study evaluated the effects of rubidium-82 (⁸²Rb) tracer injection profile using a constant-activity-rate (CA) vs a constant-flow-rate (CF) infusion to improve test-retest repeatability of MBF measurements.

Method

22 participants underwent single-session ⁸²Rb dynamic PET imaging during rest and dipyridamole stress using one of 2 test-retest infusion protocols: CA-CA (n = 12) or CA-CF (n = 10). MBF was quantified using a single-tissue-compartment model (1TCM) and a simplified retention model (SRM). Non-parametric test-retest repeatability coefficients (RPC_np) were compared between groups. Myocardium-to-blood contrast and signal-to-noise ratios of the late uptake images (2 to 6 minutes) were also compared to evaluate standard myocardial perfusion image (MPI) quality.

Results

MBF values in the CA-CA group were more repeatable (smaller RPC_np) than the CA-CF group using the 1TCM at rest alone, rest and stress combined, and stress/rest reserve (21% vs 36%, 16% vs 19%, and 20% vs 27%, P < 0.05, respectively), and using the SRM at Rest and Stress alone, Rest and Stress combined, and stress/rest reserve (21% vs 38%, 15% vs 25%, 22% vs 38%, and 23% vs 49%, P < 0.05, respectively). In terms of image quality, myocardium-to-blood contrast and signal-to-noise ratios were not significantly different between groups.

Conclusions

Constant-activity-rate 'square-wave' infusion of ⁸²Rb produces more repeatable tracer injection profiles and decreases the test-retest variability of MBF measurements, when compared to a constant-flow-rate 'bolus' administration of ⁸²Rb, especially with SRM, and without compromising standard MPI quality.

SUBMITTER: Klein R

PROVIDER: S-EPMC5966478 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Publications

Consistent tracer administration profile improves test-retest repeatability of myocardial blood flow quantification with <sup>82</sup>Rb dynamic PET imaging.

Klein Ran R Ocneanu Adrian A Renaud Jennifer M JM Ziadi Maria C MC Beanlands Rob S B RSB deKemp Robert A RA

Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology 20180601 3

<h4>Objectives</h4>Quantification of myocardial blood flow (MBF) and stress/rest flow reserve is used increasingly to diagnose multi-vessel coronary artery disease and micro-vascular disease with PET imaging. However, variability in the measurements may limit physician confidence to direct revascularization therapies based on specific threshold values. This study evaluated the effects of rubidium-82 (<sup>82</sup>Rb) tracer injection profile using a constant-activity-rate (CA) vs a constant-flow ...[more]

PMID: 27804067

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Project description:PurposeCardiac perfusion PET data can be reconstructed as a dynamic sequence and kinetic modeling performed to quantify myocardial blood flow, or reconstructed as static gated images to quantify function. Parametric images from dynamic PET are conventionally not gated, to allow use of all events with lower noise. An alternative method for dynamic PET is to incorporate the kinetic model into the reconstruction algorithm itself, bypassing the generation of a time series of emission images and directly producing parametric images. So-called "direct reconstruction" can produce parametric images with lower noise than the conventional method because the noise distribution is more easily modeled in projection space than in image space. In this work, we develop direct reconstruction of cardiac-gated parametric images for 82 Rb PET with an extension of the Parametric Motion compensation OSEM List mode Algorithm for Resolution-recovery reconstruction for the one tissue model (PMOLAR-1T).MethodsPMOLAR-1T was extended to accommodate model terms to account for spillover from the left and right ventricles into the myocardium. The algorithm was evaluated on a 4D simulated 82 Rb dataset, including a perfusion defect, as well as a human 82 Rb list mode acquisition. The simulated list mode was subsampled into replicates, each with counts comparable to one gate of a gated acquisition. Parametric images were produced by the indirect (separate reconstructions and modeling) and direct methods for each of eight low-count and eight normal-count replicates of the simulated data, and each of eight cardiac gates for the human data. For the direct method, two initialization schemes were tested: uniform initialization, and initialization with the filtered iteration 1 result of the indirect method. For the human dataset, event-by-event respiratory motion compensation was included. The indirect and direct methods were compared for the simulated dataset in terms of bias and coefficient of variation as a function of iteration.ResultsConvergence of direct reconstruction was slow with uniform initialization; lower bias was achieved in fewer iterations by initializing with the filtered indirect iteration 1 images. For most parameters and regions evaluated, the direct method achieved the same or lower absolute bias at matched iteration as the indirect method, with 23%-65% lower noise. Additionally, the direct method gave better contrast between the perfusion defect and surrounding normal tissue than the indirect method. Gated parametric images from the human dataset had comparable relative performance of indirect and direct, in terms of mean parameter values per iteration. Changes in myocardial wall thickness and blood pool size across gates were readily visible in the gated parametric images, with higher contrast between myocardium and left ventricle blood pool in parametric images than gated SUV images.ConclusionsDirect reconstruction can produce parametric images with less noise than the indirect method, opening the potential utility of gated parametric imaging for perfusion PET.

Project description:BackgroundPatient 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.MethodsWe studied 225 consecutive patients who underwent dynamic rest/stress rubidium-82 chloride (82Rb) PET imaging. Dynamic image series consisting of 30 frames were reconstructed with frame durations ranging from 5 to 80 seconds. An automated algorithm localized the RV and LV blood pools in space and time and then registered each frame to a tissue reference image volume using normalized gradient fields with a modification of a signed distance function. The computed shifts and their global and regional flow estimates were compared to those of reference shifts that were assessed by three physician readers.ResultsThe automated motion-correction shifts were within 5 mm of the manual motion-correction shifts across the entire sequence. The automated and manual motion-correction global MBF values had excellent linear agreement (R = 0.99, y = 0.97x + 0.06). Uncorrected flows outside of the limits of agreement with the manual motion-corrected flows were brought into agreement in 90% of the cases for global MBF and in 87% of the cases for global MFR. The limits of agreement for stress MBF were also reduced twofold globally and by fourfold in the RCA territory.ConclusionsAn image-based, automated motion-correction algorithm for dynamic PET across the entire dynamic sequence using normalized gradient fields matched the results of manual motion correction in reducing bias and variance in MBF and MFR, particularly in the RCA territory.

Dataset Information

Consistent tracer administration profile improves test-retest repeatability of myocardial blood flow quantification with ⁸²Rb dynamic PET imaging.

Objectives

Method

Results

Conclusions

Publications

Consistent tracer administration profile improves test-retest repeatability of myocardial blood flow quantification with <sup>82</sup>Rb dynamic PET imaging.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

Consistent tracer administration profile improves test-retest repeatability of myocardial blood flow quantification with 82Rb dynamic PET imaging.

Objectives

Method

Results

Conclusions

Publications

Consistent tracer administration profile improves test-retest repeatability of myocardial blood flow quantification with <sup>82</sup>Rb dynamic PET imaging.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Consistent tracer administration profile improves test-retest repeatability of myocardial blood flow quantification with ⁸²Rb dynamic PET imaging.