Utility of 18F-FDG uptake in various regions of Waldeyer's ring to differentiate benign from malignant lesions in the midline roof of the nasopharynx.

PURPOSE: Lymphoid hyperplasia is not uncommon in the midline roof of the nasopharynx. Most nasopharyngeal carcinoma patients present with primary tumors in the midline of the nasopharynx. The aim of this study was to evaluate the efficacy of 2-[fluorine-18] fluoro-2-deoxy-D-glucose ((18)F-FDG) PET/computed tomography (CT) to differentiate between benign and malignant lesions in the midline roof of the nasopharynx. MATERIALS AND METHODS: The data from the (18)F-FDG PET/CT images of 4846 participants were analyzed. Visual uptake, the lesions' standard uptake values (SUVs), and any abnormalities on the PET/CT images were evaluated. RESULTS: Sixty-six individuals with benign lesions and 25 with nasopharyngeal carcinoma were included in the analysis. The participants with benign and malignant lesions displayed increased (18)F-FDG uptake (SUV; mean±SD) in the midline roof of the nasopharynx (4.16±1.92 and 6.65±2.81, respectively), with SUVs significantly differing between the two types of lesions (P<0.001). An associated increased (18)F-FDG uptake in Waldeyer's ring and the salivary glands occurred in benign but not in malignant lesions. The ratio of uptake in the midline roof of the nasopharynx and the palatine tonsil in the benign lesions (0.92±0.42) was significantly lower than that in the malignant lesions (1.76±0.93) (P<0.001). CONCLUSION: The analysis of the intensity and patterns of (18)F-FDG uptake in various regions of Waldeyer's ring provides a feasible modality for the differentiation between benign lesions and malignant nasopharyngeal midline roof lesions.

The significance of alteration 2-[fluorine-18]fluoro-2-deoxy-(D)-glucose uptake in the liver and skeletal muscles of patients with hyperthyroidism.

RATIONALE AND OBJECTIVES: Hyperthyroidism leads to an enhanced demand for glucose. The hypothesis of the study is that 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) can demonstrate the alteration of systemic glucose metabolism in hyperthyroidism patients by measuring the FDG standard uptake value (SUV) in liver and skeletal muscle. MATERIALS AND METHODS: Forty-eight active hyperthyroidism patients and 30 control participants were recruited for the study. The intensity of FDG uptake in the liver and thigh muscles was graded subjectively, comprising three groups: group I, higher FDG uptake in the liver; group II, equal FDG uptake in the liver and muscles; and group III, higher FDG uptake in the muscles. Ten subjects with FDG PET scans at hyperthyroid and euthyroid status were analyzed. Serum levels of thyroxine (T4) and triiodothyronine (T3) correlated to the SUVs of the liver and muscles. RESULTS: Forty-one patients (41/48, 85.4%) showed symmetrically increased FDG uptake in the muscles (22 in group I, 9 in group II, and 17 in group III). Group I patients were significantly older than group II (P = .02) and group III (P = .001) patients. The correlation coefficient between the serum T3, T4, and SUV levels in the muscles was significant (r = 0.47-0.77, P < .01), particularly in liver and muscle FDG uptake between hyperthyroid and euthyroid states. In the 30 control subjects, there was normal physiological FDG uptake in the liver and muscles. CONCLUSION: In PET scans showing a pattern of decreased liver and increased skeletal muscle FDG uptake in hyperthyroidism patients, this change of FDG distribution is correspondence to the severity of hyperthyroidism status.

F-18 FDG PET for evaluation of bone marrow involvement in non-Hodgkin lymphoma: a meta-analysis.

BACKGROUND: In recent years, the use of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) has become widespread for the staging of lymphoma. In non-Hodgkin lymphoma (NHL), the bone marrow (BM) involvement is a sign of extensive disease, and the iliac crest BM biopsy (BMB) is the established method for the detection of BM infiltration. However, iliac crest BMB is associated with a high rate of false-negative results. We assess the ability of FDG PET or PET/CT scan to ascertain the presence of BM involvement in aggressive and indolent NHL. METHODS: The authors conducted a systematic MEDLINE search of articles published (last update, May 2010). Two reviewers independently assessed the methodological quality of each study. A meta-analysis of the reported sensitivity and specificity of each study was performed. RESULTS: Eight studies met the inclusion criteria. The studies had several design deficiencies. Pooled sensitivity and specificity for the detection of non-Hodgkin aggressive lymphoma were 0.74 (95% CI, 0.65-0.83) and 0.84 (95% CI, 0.80-0.89), respectively. Pooled sensitivity and specificity for the detection of non-Hodgkin indolent lymphoma were 0.46 (95% CI, 0.33-0.59) and 0.93 (95% CI, 0.88-0.98), respectively. CONCLUSIONS: The diagnostic accuracy of FDG PET or PET/CT scans was slightly higher but without significant statistical difference (P = 0.1507) in patients with non-Hodgkin aggressive lymphoma as compared with those with non-Hodgkin indolent lymphoma. The sensitivity to detect indolent lymphoma BM infiltration was low for FDG PET or PET/CT.

Use of laxative-augmented contrast medium in the evaluation of colorectal foci at FDG PET.

PURPOSE: To compare the diagnostic accuracy of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in the detection of colon lesions with that of delayed PET/computed tomography (CT) performed after the administration of a laxative-augmented contrast medium. MATERIALS AND METHODS: All patients gave written informed consent according to the guidelines issued by the institutional review board. In a prospective study performed from November 2005 to December 2006, images obtained in 847 patients were reviewed by two physicians in consensus. Colorectal FDG uptake on initial PET images that exceeded background FDG accumulation was graded as minimal, equivocal, or positive. When the initial PET scan revealed a colorectal region of increased uptake, either oral or anal laxative-augmented contrast medium was administered on the basis of the site of colorectal FDG focus and delayed PET/CT was performed. Initial PET findings were reevaluated and revised when necessary. Comparison was performed on a per-patient basis. Findings at histopathologic analysis and clinical follow-up served as the reference standard. The accuracy of PET was compared with that of PET/CT by using the McNemar test. RESULTS: Colorectal FDG foci were seen on initial images in 137 patients. Uptake on the initial images was reported as minimal in 14 patients, equivocal in 68, and positive in 55. With use of a laxative-augmented contrast medium and delayed PET/CT, the proportions of equivocal and positive results decreased by 84% (57 of 68 patients) and 58% (18 of 31 patients), respectively. The accuracy of delayed PET/CT in the depiction of colorectal cancer was greater than that of initial PET (93.4% [128 of 137 patients] vs 71.5% [98 of 137 patients], respectively; P < .01). CONCLUSION: Delayed PET/CT with laxative-augmented contrast medium is more accurate than initial PET alone in the detection of colorectal cancer. This approach has promise as a tool for guiding decisions about how to treat patients with colorectal FDG foci. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101193/-/DC1.