Objective:We aimed to improve prediction of outcome for patients with colorectal liver metastases, via prognostic models incorporating PET-derived measures, including radiomic features that move beyond conventional standard uptake value (SUV) measures.
Patients and Methods:A range of parameters including volumetric and heterogeneity measures were derived from FDG PET images of 52 patients with colorectal intrahepatic-only *
BackgroundPET/CT with the radioactively labelled galactose analogue 2-18F-fluoro-2-deoxy-D-galactose (18F-FDGal) can be used to quantify the hepatic metabolic function and visualise regional metabolic heterogeneity. We determined the day-to-day variation in humans with and without liver disease. Furthermore, we examined whether the standardised uptake value (SUV) of 18F-FDGal from static scans can substitute the hepatic systemic clearance of 18F-FDGal (K
met, mL blood/min/mL liver tissue/) quantified from dynamic scans as measure of metabolic function.Four patients with cirrhosis and six healthy subjects underwent two 18F-FDGal PET/CT scans within a median interval of 15 days for determination of day-to-day variation. The correlation between K
met and SUV was examined using scan data and measured arterial blood concentrations of 18F-FDGal (blood samples) from 14 subjects from previous studies. Regional and whole-liver values of K
met and SUV along with total metabolic liver volume and total metabolic liver function (total SUV, average SUV multiplied by total metabolic liver volume) were calculated.ResultsNo significant day-to-day differences were found for K
met or SUV. SUV had higher intraclass correlation coefficients than K
met (0.92–0.97 vs. 0.49–0.78). The relationship between K
met and SUV was linear. Total metabolic liver volume had non-significant day-to-day variation (median difference 50 mL liver tissue; P = 0.6). Mean total SUV in healthy subjects was 23,840 (95% CI, 21,609; 26,070), significantly higher than in the patients (P < 0.001).ConclusionsThe reproducibility of 18F-FDGal PET/CT was good and SUV can substitute K
met for quantification of hepatic metabolic function. Total SUV of 18F-FDGal is a promising tool for quantification of metabolic liver function in pre-treatment evaluation of individual patients.
BackgroundPositron emission tomography (PET) with the liver-specific galactose tracer 2-[18F]fluoro-2-deoxy-d-galactose (18F-FDGal) may improve diagnosis of hepatocellular carcinoma (HCC). The aim of this study was to test which of three different 18F-FDGal PET protocols gives the highest tumour-to-background (T/B) ratio on PET images and thus better detection of HCC tumours.MethodsTen patients with a total of 15 hepatic HCC tumours were enrolled prior to treatment. An experienced radiologist defined volumes of interest (VOIs) encircling HCC tumours on contrast-enhanced CT (ce-CT) images. Three PET/CT protocols were conducted following an intravenous 18F-FDGal injection: (i) a 20-min dynamic PET/CT of the liver (to generate a 3D metabolic image), (ii) a traditional static whole-body PET/CT after 1 h, and (iii) a late static whole-body PET/CT after 2 or 3 h. PET images from each PET/CT protocol were fused with ce-CT images, and the average standardized uptake values (SUV) in tumour and background liver tissue were used to calculate (T/B) ratios. Furthermore, Tpeak/B ratios were calculated using the five hottest voxels in all hot tumours. The ratios for the three different PET protocols were compared.ResultsFor the individual tumours, there was no significant difference in the T/B ratio between the three PET protocols. The metabolic image yielded higher Tpeak/B ratios than the two static images, but it was easier to identify tumours on the static images. One extrahepatic metastasis was detected.ConclusionsNeither metabolic images nor static whole-body images acquired 2 or 3 h after 18F-FDGal injection offered an advantage to traditional whole-body PET/CT images acquired after 1 h for detection of HCC.
The clinical study demonstrates the feasibility for FTP in patients with liver metastases and it was possible to minimize the radiation dose to the best functioning liver tissue.
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