Presence of a focal colonic FDG uptake incidental finding on a PET/CT scan justifies a colonoscopy to detect (pre-)malignant lesions. The fusion of PET and CT images allows an accurate localization of the lesions. PET/CT is a useful tool to differentiate pathologic from physiologic FDG uptake.
This prospective study aimed to compare the diagnostic performance of 18 F-fluorocholine and 18 F-FDG for detecting and staging hepatocellular carcinoma (HCC) in patients with chronic liver disease and suspected liver nodules. Methods: Whole-body PET/CT was performed in a random order at 10 min after injection of 4 MBq of 18 F-fluorocholine per kilogram and at 1 h after injection of 5 MBq of 18 F-FDG per kilogram. PET/CT results were read in a masked manner by 2 specialists, and diagnostic performance was assessed from the results of consensus masked reading. Those focal lesions appearing with increased or decreased activity, compared with background, on 18 F-fluorocholine PET/CT were considered positive for malignancy. The standard of truth was determined on a per-site basis using data from a histologic examination and a follow-up period of more than 6 mo; on a per-patient basis, the Barcelona criteria were also accepted as a proof of HCC in 5 patients. Results: Eighty-one patients were recruited; standard of truth was determined in 59 cases. HCC was diagnosed in 34 patients. Therefore, sensitivity was 88% for 18 F-fluorocholine and 68% for 18 F-FDG (P 5 0.07), and in 70 sites, sensitivity was 84% for 18 F-fluorocholine, significantly better than the 67% for 18 F-FDG (P 5 0.01). Of the 11 patients with well-differentiated HCC, 6 had a positive result with 18 F-fluorocholine alone, whereas 18 F-FDG was never positive alone; corresponding site-based sensitivity was 94% for 18 F-fluorocholine and 59% for 18 F-FDG (P 5 0.001). The detection rate of 18 sites corresponding to other malignancies was 78% for 18 F-fluorocholine and 89% for 18 F-FDG. In nonmalignant sites, 18 F-fluorocholine appeared less specific than 18 F-FDG (62% vs. 91% P , 0.01) because of uptake by focal nodular hyperplasia. Conclusion: 18 F-fluorocholine was significantly more sensitive than 18 F-FDG at detecting HCC, in particular in well-differentiated forms. In contrast, 18 F-FDG appeared somewhat more sensitive at detecting other malignancies and was negative in focal nodular hyperplasia. Thus 18 F-fluorocholine appears to be a useful PET/CT tracer for the detection and surveillance of HCC; however, performing PET/CT with both radiopharmaceuticals seems to be the best option.
FCH provides a high detection rate for HCC, making it potentially useful in the initial evaluation of HCC or in the detection of recurrent disease. The favourable result of this proof-of-concept study opens the way to a phase III prospective study.
Our study demonstrated that for patients undergoing the 2-day protocol for sentinel node procedure in early stage breast cancer, the optimal imaging time would be to perform lymphoscintigraphy 1 h after injection, with the possibility of imaging patients the following day in cases where lymphoscintigraphy was negative.
In this population of patients with ground-glass opacities selected on CT suggestive of BAC or with a history of BAC and a recent lung anomaly on CT, FCH detected all malignant lesions with at least a 2.0 cm short axis. However, FDG had similar performance.
Iterative reconstruction algorithms, such as the ordered subsets expectation maximisation (OS-EM), are a promising alternative to filtered backprojection (FBP). The aims of this study were first to optimise the OS-EM algorithm in terms of iteration number and to study the usefulness of post-filtering, and second to compare OS-EM and FBP for image reconstruction on a fluorine-18 fluorodeoxyglucose ((18)F-FDG) dual-head camera (DHC). These two goals were addressed using phantom acquisitions. The performances of these algorithms were also studied in patient acquisitions performed on a DHC and a PET on the same day. Phantom experiments were performed on a DHC using a Jaszczak phantom containing six spheres filled with (18)F-FDG, two background levels (0.95, 6.80 kBq/ml) and three object contrasts (5.9, 3.7, 2.7). The reconstruction algorithms were FBP with a Gaussian filter (FWHM 0.5-2 pixel width) and OS-EM using 8-128 equivalent iterations (equivalent to the ML-EM algorithm) with and without Gaussian post-filtering [OS-EM (iterations, pixel width)]. Contrast recovery coefficient (CRC) and noise characteristics were assessed. Twenty-two patients (21 male, one female; age 55+/-15 years) with lung cancer underwent, on the same day, PET (1 h post injection of 37 MBq/kg (18)F-FDG) and DHC acquisitions (3 h post injection). DHC data were reconstructed using six methods: FBP (1), OS-EM (16), (40), (40,1), (64) and (64,1). These sets were evaluated by two observers and compared to PET reconstructed with OS-EM (16). The number of detected lesions and the visual quality were assessed. A marked improvement in CRC was observed with OS-EM as compared with FBP when more than 24 iterations were used. The CRC increased markedly from 8 to 40 iterations and then reached a plateau. The noise was stable until 40 iterations and then increased. The best compromise was obtained for OS-EM (32) and OS-EM (40,1). For the patient study, OS-EM provided images of better visual quality, but with no significant difference in detection sensitivity. OS-EM was superior to FBP in terms of contrast recovery and noise level. The optimal compromise between contrast recovery and noise was obtained for OS-EM (32) and (40,1) on the phantom study. The clinical study showed that OS-EM yielded images of better visual quality but with no improvement in terms of detection of lung cancer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.