Attenuation-corrected vs. nonattenuation-corrected 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography in oncology: a systematic review.

PURPOSE: To perform a systematic review and meta-analysis to determine the diagnostic accuracy of attenuation-corrected (AC) vs. nonattenuation-corrected (NAC) 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography (FDG-PET) in oncological patients. PROCEDURES: Following a comprehensive search of the literature, two reviewers independently assessed the methodological quality of eligible studies. The diagnostic value of AC was studied through its sensitivity/specificity compared to histology, and by comparing the relative lesion detection rate reported with NAC-PET vs. AC, for full-ring and dual-head coincidence PET (FR- and DH-PET, respectively). RESULTS: Twelve studies were included. For FR-PET, the pooled sensitivity/specificity on a patient basis was 64/97% for AC and 62/99% for NAC, respectively. Pooled lesion detection with NAC vs. AC was 98% [95% confidence interval (95% CI): 96-99%, n = 1,012 lesions] for FR-PET, and 88% (95% CI:81-94%, n = 288 lesions) for DH-PET. CONCLUSIONS: Findings suggest similar sensitivity/specificity and lesion detection for NAC vs. AC FR-PET and significantly higher lesion detection for NAC vs. AC DH-PET.

Initial experience with a prototype dual-crystal (LSO/NaI) dual-head coincidence camera in oncology.

The aim of this study was to evaluate the in vivo performance of a prototype dual-crystal [lutetium oxyorthosilicate (LSO)/sodium iodide (NaI)] dual-head coincidence camera (DHC) for PET and SPET (LSO-PS), in comparison to BGO-PET with fluorine-18 fluorodeoxyglucose (FDG) in oncology. This follows earlier reports that LSO-PS has noise-equivalent counting (NEC) rates comparable to partial ring BGO-PET, i.e. clearly higher than standard NaI DHCs. Twenty-four randomly selected oncological patients referred for whole-body FDG-PET underwent BGO-PET followed by LSO-PS. Four nuclear medicine physicians were randomised to read a single scan modality, in terms of lesion intensity, location and likelihood of malignancy. BGO-PET was considered the gold standard. Forty-eight lesions were classified as positive with BGO-PET, of which LSO-PS identified 73% (95% CI 60-86%). There was good observer agreement for both modalities in terms of intensity, location and interpretation. Lesions were missed by LSO-PS in 13 patients in the chest ( n=6), neck ( n=3) and abdomen ( n=4). The diameter of these lesions was estimated to be 0.5-1 cm. Initial results justify further evaluation of LSO-PS in specific clinical situations, especially if a role as an instrument of triage for PET is foreseen.

Biologic correlates of (18)fluorodeoxyglucose uptake in human breast cancer measured by positron emission tomography.

PURPOSE: Variable uptake of the glucose analog (18)fluorodeoxyglucose (FDG) has been noticed in positron emission tomography (PET) studies of breast cancer patients, with low uptake occurring especially in lobular cancer. At present, no satisfactory biologic explanation exists for this phenomenon. This study compared (18)FDG uptake in vivo with biomarkers expected to be involved in the underlying biologic mechanisms. PATIENTS AND METHODS: Preoperative (18)FDG-PET scans were performed in 55 patients. (18)FDG activity was assessed visually by three observers using a four-point score. Tumor sections were stained by immunohistochemistry for glucose transporter-1 (Glut-1); Hexokinase (HK) I, II, and III; macrophages; hypoxia-inducible factor-1-alfa (HIF-1alpha); vascular endothelial growth factor (VEGF(165)); and microvessels. Mitotic activity index (MAI), amount of necrosis, number of lymphocytes, and tumor cells/volume were assessed. RESULTS: There were positive correlations between (18)FDG uptake and Glut-1 expression (P <.001), MAI (P =.001), amount of necrosis (P =.010), number of tumor cells/volume (P =.009), expression of HK I (P =.019), number of lymphocytes (P =.032), and microvessel density (r =.373; P =.005). HIF-1alpha, VEGF(165), HK II, HK III, and macrophages showed no univariate correlation with (18)FDG. In logistic regression, however, HIF-1alpha and HK II added value to MAI and Glut-1. CONCLUSION: (18)FDG uptake in breast cancer is a function of microvasculature for delivering nutrients, Glut-1 for transportation of (18)FDG into the cell, HK for entering (18)FDG into glycolysis, number of tumor cells/volume, proliferation rate (also reflected in necrosis), number of lymphocytes (not macrophages), and HIF-1alpha for upregulating Glut-1. Together, these features explain why breast cancers vary in (18)FDG uptake and elucidate the low uptake in lobular breast cancer.