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Jørgen Frøkiær

Low-dose myocardial blood flow imaging using 82Rb-PET (RUBILOW 2.0)

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Aim: Relative and absolute measures of myocardial blood flow (MBF) can be derived from a 82Rb PET/CT scan using list mode data to extract static, gated and dynamic PET series. High doses of 82Rb are used to maximize image quality in especially static images. High doses require large eluate volumes, may degrade scanner dead time performance at first pass and decreases generator lifetime. Lower doses will expand the availability of 82Rb PET/CT and lower doses to personnel and patients. The aim of the current study was to examine MBF with a low dose (LD) 82Rb protocol compared to the institution’s standard (STD) protocol. Methods: Twenty-one patients referred to 82Rb PET were included in the study. Patients were examined during rest and stress with repeated LD (740 MBq) and STD dose (1110 MBq) Rb-PET during the same imaging session. Regional and global rest and stress MBF values, total perfusion deficit (TPD), ejection fraction (EF) and %-perfusion using the 17-segment model were calculated using commercially available software QPET (Cedars Sinai). Results: Five patients had to be excluded due to motion during STD (n=2) and LD (n=3). For the remaining patients, there was excellent correlation between STD and LD global MBF (STD=0.91xLD+ 0.08, R²=0.95, p<0.001). Mean global MBF (±SD) at rest was 1.01 ±0.31 and 1.06±0.30 mL/g/min at STD and LD (p=0.17), and at stress 2.44±0.48 and 2.57±0.55 mL/g/min at STD and LD (p=0.07), respectively. On the segmental level, correlation between STD and LD MBF was high (STD=0.91xLD+0.09, R2=0.92, p<0.001). Mean segmental MBF (±SD) at rest was 1.01 ±0.35 and 1.06±0.35 mL/g/min at STD and LD (p<0.001), respectively. At stress mean segmental MBF was 2.44±0.70 and 2.58 ±0.75 mL/g/min at STD and LD (p<0.001), respectively. There was an excellent correlation between STD and LD TPD (STD=0.90xLD-0.42, R2=0.95, p<0.001). Mean TPD with STD was 7.5±6.9% and 8.8±7.5% with LD (p<0.001). Mean %-perfusion with STD was 77.3±9.0% and 76.4±9.1% with LD patients (p<0.001) with a good correlation between STD and LD %-perfusion (STD=0.92xLD+7.15, R²=0.86, p<0.001). Mean EF with STD patients was 65±9% and 65±8% in LD patients (p=0.90) with a good correlation (STD=1.06xLD-3.70, R2=0.90, p<0.001). Conclusions: The 82Rb dose can be lowered to 740 MBq without loss of diagnostic accuracy for both absolute and relative measurements. The low dose protocol should be implemented into clinical routine if a modern scanner is available. This will reduce radiation burden and increase patient throughput per generator.
Original languageEnglish
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
IssueSuppl 2
Publication statusPublished - 2017

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