Impact d’une acquisition TEP/TDM au 18FDG synchronisée à la respiration pour le diagnostic des lésions hépatiques

Abstract

IntroductionThe aim of this study was to evaluate the impact of a respiratory-gated PET-CT acquisition (multiphase method) on the liver lesions detectability and quantification. Patients and methodsTwenty-one patients with known or suspected liver lesions and referred to our department for 18F-fluorodeoxyglucose PET were prospectively included. The standard 3D PET-CT was followed by a 4D PET-CT acquisition (6 phases of 2minutes). The detectability was studied on a per-patient and a per-lesion basis. The following quantitative parameters have been compared: lesions SUVmax, normal liver SUVmax, SUVmean and SUVSD, target to background ratios (TBR), lesions metabolic volume and TLG. ResultsFifteen of the 21 patients were found to have 63 liver lesions on the clinical follow-up based on CT or MRI (13 patients) and histopathological examination (2 patients). On a per-patient basis, 4D PET did not improve the already high sensibility of the 3D PET (93%). On a per-lesion basis, the sensibility was not significantly improved (84 vs 80%), including the infracentimetric lesions subgroup. 4D PET led to a better contrast in images thanks to the decrease of normal liver SUVmean (−10%), SUVmax (−16%) and SUVSD (−35%), and the non-significant increase of TBR (+19%; P=0.07). The 4D CT attenuation correction did not modify the lesions SUVmax, including those near the diaphragm. ConclusionThe contribution of a 4D PET-CT acquisition (multiphase method) appears to be non-effective for the improvement of liver lesions diagnosis, even if an increased sensitivity seems present in infracentimetric lesions thanks to a better lesion-to-liver contrast. The use of standard CT for attenuation correction, which is equivalent to 4D CT, seems legitimate to limit the patient's dosimetry.