FDG PET/CT early dynamic blood flow and late standardized uptake value determination in hepatocellular carcinoma.

PURPOSE: To prospectively determine whether fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) early dynamic blood flow estimates could be used to discriminate hepatocellular carcinoma (HCC) from background liver and to characterize HCC in patients with and those without angioinvasion; and to evaluate the association between blood flow measures at FDG PET/CT with metabolism in HCCs. MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained for this prospective study. Twenty-one consecutive patients (mean age, 65 years) with 30 established HCCs (mean size, 5.5 cm; seven lesions in five patients with angioinvasion) underwent a blood flow study with an FDG dynamic scan divided into 18 sequences of 5 seconds each and a standard PET/CT scan. On the dynamic study, three independent operators obtained volumes of interest (VOIs) for which three blood flow estimates were calculated (hepatic perfusion index [HPI], time to peak [TTP], and peak intensity [PI]). On the late study, a VOI was placed on the fused scan for each HCC, and maximum standardized uptake value (SUV(max)) was obtained. By using a mixed-effects model analysis, comparison of blood flow estimates between HCC with and that without angioinvasion and background liver was performed. The association between blood flow estimates and SUV(max) was also assessed. RESULTS: HPI and TTP showed better performance than did SUV(max) for discriminating HCC and background liver (areas under receiver operating characteristic curve: 0.96, 0.95, and 0.83, respectively; P < .05). HPI was higher in HCC in patients with angioinvasion (0.91 ± 0.15 [standard deviation]) than in those without angioinvasion (0.80 ± 0.18; P = .03). There was no difference in SUV(max) between HCC in patients with and those without angioinvasion (7.8 ± 2.9 vs 6.3 ± 3.4; P = .85). No clear association was found between HPI, PI, or TTP and SUV(max) (P = .49, .77, and .91, respectively). CONCLUSION: Early dynamic blood flow FDG PET/CT may be used to help discriminate and characterize HCC tumors.

Dual-energy based spectral electronic cleansing in non-cathartic computed tomography colonography: an emerging novel technique.

Computed tomography colonography (CTC) with reduced or without bowel catharsis and with fecal tagging has emerged to improve CTC tolerability in patients and their subsequent compliance with colorectal cancer screening. With fecal tagging, electronic cleansing is performed by postprocessing software that removes remnants of contrast material. However, because the technique is threshold based, artifacts that lower the image quality and accuracy of the examination may be noted. Spectral electronic cleansing, based on dual-energy CT and on material-specific cleansing, decreases the number of artifacts and improves image quality. In this review we describe spectral cleansing with reduced catharsis CTC and illustrate its potential benefits.