Automatic extraction of forward stroke volume using dynamic PET/CT: a dual-tracer and dual-scanner validation in patients with heart valve disease

Abstract

BackgroundThe aim of this study was to develop and validate an automated method for extracting forward stroke volume (FSV) using indicator dilution theory directly from dynamic positron emission tomography (PET) studies for two different tracers and scanners.Methods35 subjects underwent a dynamic 11C-acetate PET scan on a Siemens Biograph TruePoint-64 PET/CT (scanner I). In addition, 10 subjects underwent both dynamic 15O-water PET and 11C-acetate PET scans on a GE Discovery-ST PET/CT (scanner II). The left ventricular (LV)-aortic time-activity curve (TAC) was extracted automatically from PET data using cluster analysis. The first-pass peak was isolated by automatic extrapolation of the downslope of the TAC. FSV was calculated as the injected dose divided by the product of heart rate and the area under the curve of the first-pass peak. Gold standard FSV was measured using phase-contrast cardiovascular magnetic resonance (CMR).ResultsFSVPET correlated highly with FSVCMR (r = 0.87, slope = 0.90 for scanner I, r = 0.87, slope = 1.65, and r = 0.85, slope = 1.69 for scanner II for 15O-water and 11C-acetate, respectively) although a systematic bias was observed for both scanners (p < 0.001 for all). FSV based on 11C-acetate and 15O-water correlated highly (r = 0.99, slope = 1.03) with no significant difference between FSV estimates (p = 0.14).ConclusionsFSV can be obtained automatically using dynamic PET/CT and cluster analysis. Results are almost identical for 11C-acetate and 15O-water. A scanner-dependent bias was observed, and a scanner calibration factor is required for multi-scanner studies. Generalization of the method to other tracers and scanners requires further validation.

Automatic Extraction of Myocardial Mass and Volume Using Parametric Images from Dynamic Nongated PET

“…Therefore, care has to be taken in interpretation of LVEF and stroke volume values. Indicator-dilution methods can be applied to dynamic PET data for assessing forward stroke volume (15), which may serve as an alternative.…”

“…Arterial (C A (t)), venous (C V (t)), and plasma (C P (t)) input functions were obtained using cluster analysis as described previously (15), applying a previously described metabolite correction (16). Using these input functions, parametric images were calculated using a basis-function approach (12,17) of the single-tissue-compartment model (18):…”

“…Recently, automatic parametric imaging became available for 15 O-water (12), and the same methodology can be applied to most other tracers. Parametric images visualize tracer kinetic parameters on the pixel level and are generated during routine quantitative analysis of dynamic PET images.…”

“…The need for separate reconstructions to assess LV volume and to quantify molecular processes increases workload significantly and has limited the use of combined functional and molecular assessments of the heart. In addition, for some PET tracers such as 15 O-water, no specific uptake is seen in the myocardium, ruling out the use of electrocardiogram-gated reconstructions to assess myocardial function.…”

“…Parametric images visualize tracer kinetic parameters on the pixel level and are generated during routine quantitative analysis of dynamic PET images. For a single-tissue-compartment model, used for tracers such as 82 Rb, 15 O-water, and 11 C-acetate, images of tracer uptake, tracer washout, and the arterial and rightventricular blood fractions are obtained. Combining these parametric images, it might be possible to identify the LV cavity, the LV wall, and LV geometry with a sufficiently high accuracy for use in clinical reporting and research.…”