Intra-individual comparison of PET/CT with different body weight-adapted FDG dosage regimens

Abstract

Background18F-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/ computed tomography (CT) imaging demands guidelines to safeguard sufficient image quality at low radiation exposure. Various FDG dose regimes have been investigated; however, body weight-adapted dose regimens and related image quality (IQ) have not yet been compared in the same patient.PurposeTo investigate the relationship between FDG dosage and image quality in PET/CT in the same patient and determine prerequisites for low dosage scanning.Material and MethodsThis study included 61 patients undergoing a clinically indicated PET/CT imaging study and follow-up with a normal (NDS, 5 MBq/kg body weight [BW]) and low dosage scanning protocol (LDS, 4 MBq/kg BW), respectively, using a Discovery VCT64 scanner. Two blinded and independent readers randomly assessed IQ of PET using a 5-point Likert scale and signal-to-noise ratio (SNR) of the liver.ResultsBody mass index (BMI) was significantly lower at LDS (P = 0.021) and represented a significant predictor of SNR at both NDS (P < 0.001) and LDS (P = 0.005). NDS with a mean administered activity of 340 MBq resulted in significantly higher IQ (P < 0.001) and SNR as compared with LDS with a mean of 264 MBq (F-value = 23.5, P < 0.001, mixed model ANOVA adjusted for covariate BMI). Non-diagnostic IQ at LDS was associated with a BMI > 22 kg/m2.ConclusionFDG dosage significantly predicts IQ and SNR in PET/CT imaging as demonstrated in the same patient with optimal IQ achieved at 5 MBq/kg BM. PET/CT imaging at 4 MBq/kg BW may only be recommended in patients with a BMI ≤ 22 kg/m2 to maintain diagnostic IQ.

Clinical evaluation of a block sequential regularized expectation maximization reconstruction algorithm in 18F-FDG PET/CT studies

“…As shown in a study by Geismar et al [35] a decreased signal-to-noise ratio in the liver parenchyma is one of the main limitations for dose reduction. Therefore, the radiation burden could potentially be reduced by using BSREM reconstructions.…”

A JAFROC study of nodule detection performance in CT images of a thorax acquired during PET/CT

“…5 Patient dose associated with PET/CT can be very high, and a high proportion of the dose is due to the diagnostic quality (DQ) CT examination. Recent technological improvements, notably time of flight (TOF), 6,7 have been implemented to enable the superior spatial resolution of modern PET/CT systems, and along with a strategy of calculating weight based injected activity [8][9][10] it has resulted in reduced radiation dose, with a preference to increase emission time rather than injected activity for obese patients. 6 Early reports of radiation dose in PET/CT, combining 18 F-FDG with DQ CT could produce effective dose in the range of 24-46 mSv.…”

Estimation of activity of administered 18F-fluorodeoxyglucose by measurement of the dose equivalent rate on the right temporal region of the head

“…Intravenous administration of FDG is sometimes halted due to extravasation of FDG, pain, or malfunction of injection devices. In such cases, estimations of the FDG dosage injected prior to halting administration may be helpful in making a decision on how to proceed, whether to perform venipuncture at a different site to inject additional FDG or to estimate the eventual influence of underdosing on standardized uptake values (SUVs) and image quality [4–6]. Thus, the activity remaining in the line and syringe may be estimated by using a radionuclide calibrator.…”