Incidental focal hypermetabolic colorectal lesions identified by positron emission tomography: prevalence of malignancy.

Colorectal cancer is commonly diagnosed in the United State and is one of the leading causes of cancer deaths. Positron emission tomography has been used for the evaluation and management for patients with colorectal cancer. Frequently, abnormal incidental lesions are detected on positron emission tomography. This article will review current literature for the prevalence of malignancy and pre-malignancy in incidental focal hypermetabolic colorectal lesions detected by positron emission tomography and briefly discuss its clinical impact.

Systematic review: prevalence of malignant incidental thyroid nodules identified on fluorine-18 fluorodeoxyglucose positron emission tomography.

PURPOSE: To review current literature and determine the prevalence of malignant incidental focal hypermetabolic thyroid lesions detected by fluorine-18 fluorodeoxyglucose positron emission tomography (F-FDG-PET). MATERIALS AND METHODS: Studies evaluating thyroid carcinomas discovered incidentally on F-FDG-PET were systematically searched in the MEDLINE, CINAHL, and Evidence-Based Medicine (EBM) Reviews from 1998 to 2007. Studies were eligible for inclusion with the following criteria: F-FDG-PET studies carried out on humans, long-term clinical follow-up or presence of histological confirmation of thyroid disease, and if studies reported the prevalence of abnormal F-FDG-PET scans with thyroid lesions and confirmed pathological thyroid disease. Studies were excluded if (1) there was no confirmed diagnosis, (2) there was a history of thyroid cancer, (3) they were carried out for diagnoses of thyroid abnormalities, or (4) they were case series. Two reviewers independently reviewed each study's eligibility and abstracted the data. RESULTS: Eighteen articles met criteria resulting in a total of 55 160 patients with 571 patients (1%) having an unexpected focal abnormality in the thyroid gland. Diagnostic confirmations were obtained in 322 patients. Among the confirmed diagnoses, 200 (62.1%) were benign, 107 (33.2%) were malignant, and 15 (4.7%) were indeterminate or a patient without a clear diagnosis. Papillary thyroid carcinoma was the most prevalent thyroid malignancy (82.2%). Eight studies reporting individual maximum standard uptake values were included in a subanalysis. The mean maximum standard uptake value for 73 benign lesions was 4.6+/-2.1, and for the 52 malignant lesions was 6.8+/-4.6 (P<0.001). CONCLUSION: The high prevalence of malignancy associated with focal hypermetabolic thyroid nodules found on F-FDG-PET warrants further evaluation when detected.

Meta-analysis: comparison of F-18 Fluorodeoxyglucose-positron emission tomography and bone scintigraphy in the detection of bone metastases in patients with breast cancer.

PURPOSE: To evaluate the diagnostic properties of FDG-PET and bone scintigraphy in the detection of osseous metastases in patients with breast cancer. MATERIALS AND METHODS: Studies evaluating the diagnostic accuracy of FDG-PET and bone scintigraphy in the diagnosis of osseous metastasis were systematically searched for in the MEDLINE, CINAHL, and EBM Review databases from January 1995 to November 2006. Two reviewers independently abstracted data including research design, sample size, imaging technique and technical characteristics, reference standard, method of image interpretation, and totals of true positives, false positives, true negatives, and false negatives. Per-patient and per-lesion pooled sensitivity and specificity, and area under summary receiver operating characteristic curves were calculated using Meta-Test software. RESULTS: The pooled patient-based sensitivity for FDG-PET was 81% (95% CI: 70%-89%), specificity was 93% (95% CI: 84%-97%), and the area under the curve (AUC) was 0.08. The pooled sensitivity of bone scan was 78% (95% CI: 67%-86%), specificity was 79% (95% CI: 40%-95%), and the AUC was 0.43. The pooled lesion-based sensitivity for FDG-PET was 69% (95% CI: 28%-93%), specificity was 98% (95% CI: 87%-100%), and the AUC was 0.09. The pooled sensitivity for bone scan was 88% (95% CI: 82%-92%), specificity was 87% (95% CI: 29%-99%), and the AUC was 0.81. CONCLUSIONS: It remains inconclusive whether FDG-PET or bone scintigraphy is superior in detecting osseous metastasis from breast cancer. However, FDG-PET does have a higher specificity and may better serve as a confirmatory test than bone scintigraphy and used to monitor response to therapy.