Meta-analysis of the performance of (18)F-FDG PET in cutaneous melanoma.

INTRODUCTION: The aim of this study was to perform a systematic review of the literature to evaluate the accuracy of FDG-PET in staging and restaging of cutaneous melanoma. METHODS: Systematic methods were used to identify, select, and evaluate the methodologic quality of the studies as well as to summarize the overall findings of sensitivity and specificity. The search strategy consisted of identifying studies published between 2000 and 2006. Inclusion criteria were studies that evaluated the diagnostic performance of FDG-PET in staging/restaging of cutaneous melanoma. The results were compared and pooled with a meta-analysis published previously that included studies published until 1999. The meta-analysis included 95% confidence intervals (CI) of sensitivity, specificity, likelihood-ratio (LR), and diagnostic-odds-ratio (DOR). RESULTS: The quantitative meta-analysis included 24 studies that were analysed in two groups: eight studies were included only in the regional staging analysis (group I), 13 studies were included only in the detection of distant metastases analysis (group II), and three studies were included in both analyses. Compliance with the methodologic-quality criteria was acceptable. We analysed the results of data presented in patients, lesions, basins, lymph-nodes, areas, and scans. Regarding the performance of FDG-PET in the detection of metastases, the pooled studies presented homogeneity for the negative-LR (0.15; 95% CI, 0.10-0.22) when analyzing lesions. When analyzing scans, there was global homogeneity for specificity (0.86; 95% CI, 0.77-0.92), positive-LR (5.86; 95% CI, 3.64-9.43), and DOR (37.89; 95% CI, 15.80-90.86). The pooled studies presented heterogeneity for the other items analysed. Regarding the detection of regional metastases, when analyzing lymph-nodes there was global homogeneity for specificity (0.99; 95% CI, 0.97-0.99; P = 0.101). The meta-regression evidenced that the variable that most influenced the DOR of the different studies and that can explain the heterogeneity was the year of publication; this may be related to the evolution of PET technology and an improvement of sensitivity/specificity. CONCLUSION: FDG-PET is not useful in the evaluation of regional metastases, as it does not detect microscopic disease. However, FDG-PET could be useful in the detection of distant metastases, and could suggest its utility in the management of patients with cutaneous melanoma.

Evaluating early dementia with and without assessment of regional cerebral metabolism by PET: a comparison of predicted costs and benefits.

UNLABELLED: Evaluating dementia in patients with early symptoms of cognitive decline is clinically challenging. Growing evidence indicates that appropriate incorporation of PET into the clinical work-up can improve diagnostic and prognostic accuracy with respect to Alzheimer's disease (AD), the most common cause of dementia in the geriatric population. The precise diagnostic role of PET and its economic impact in this context, however, have not been systematically examined previously. METHODS: We compared the relative value of 2 strategies for assessing whether early AD is responsible for cognitive symptoms in geriatric patients: (a) a conventional approach, based largely on establishing clinical criteria for the presence of dementia and excluding non-AD etiologies that could contribute to the patient's symptoms, and (b) a proposed approach using PET to examine regional cerebral metabolism and look for characteristic patterns of abnormal metabolism. The total costs (measured in dollars) and benefits (measured in number of accurate diagnoses) of diagnostic testing and clinical outcomes accruing to each strategy were calculated using formalized tools of decision analysis. The primary outcome measure by which the strategies were compared was the ratio of costs to benefits obtained following each approach. RESULTS: Following the proposed approach led to improved accuracy in identifying early AD, without adding to the overall costs of diagnosis and treatment ($3,433 vs. $3,564 per patient approached by the proposed or conventional algorithm, respectively). The strategy making use of PET was associated with a reduced rate of false-negative and false-positive findings compared with the conventional approach (3.1% vs. 8.2% and 12.0% vs. 23.0%, respectively, at a prevalence of 51.6% in the studied symptomatic population) and a cost savings of $1,138 per correct diagnosis rendered ($4,047 vs. $5,185). The lower cost per unit benefit for the proposed strategy was maintained over a wide range of tested values for variables of sensitivity, specificity, costs of PET and long-term care, and varying approaches to the use of structural neuroimaging. CONCLUSION: Appropriate use of PET for evaluating early dementia in geriatric patients can add valuable information to the clinical work-up, without adding to the overall costs of evaluation and management, resulting in a greater number of patients being accurately diagnosed for the same level of financial expenditure. Thus, the opportunity exists for diminishing the morbidity of dementia economically, with earlier institution of more appropriate management in evaluated patients.