Assessment of the diagnostic accuracy of 18F-FDG PET/CT in prosthetic infective endocarditis and cardiac implantable electronic device infection: comparison of different interpretation criteria.

PURPOSE: The diagnosis of prosthetic valve (PV) infective endocarditis (IE) and infection of cardiac implantable electronic devices (CIEDs) remains challenging. The aim of this study was to assess the usefulness of 18F-FDG PET/CT in these patients and analyse the interpretation criteria. METHODS: We included 41 patients suspected of having IE by the Duke criteria who underwent 18F-FDG PET/CT. The criteria applied for classifying the findings as positive/negative for IE were: (a) visual analysis of only PET images with attenuation-correction (AC PET images); (b) visual analysis of both AC PET images and PET images without AC (NAC PET images); (c) qualitative analysis of NAC PET images; and (d) semiquantitative analysis of AC PET images. 18F-FDG PET/CT was considered positive for IE independently of the intensity and distribution of FDG uptake. The gold standard was the Duke pathological criteria (if tissue was available) or the decision of an endocarditis expert team after a minimum 4 months follow-up. RESULTS: We studied 62 areas with suspicion of IE, 28 areas (45 %) showing definite IE and 34 (55 %) showing possible IE. Visual analysis of only AC PET images showed poor diagnostic accuracy (sensitivity 20 %, specificity 57 %). Visual analysis of both AC PET and NAC PET images showed excellent sensitivity (100 %) and intermediate specificity (73 %), focal uptake being more frequently associated with IE. The accuracy of qualitative analysis of NAC PET images depended on the threshold: the maximum sensitivity, specificity and accuracy achieved were 88 %, 80 %, 84 %, respectively. In the semiquantitative analysis of AC PET images, SUVmax was higher in areas of confirmed IE than in those without IE (∆SUVmax 2.2, p < 0.001). When FDG uptake was twice that in the liver, IE was always confirmed, and SUVmax 5.5 was the optimal threshold for IE diagnosis using ROC curve analysis (area under the curve 0.71). CONCLUSION: The value of 18F-FDG PET/CT in the diagnosis of suspected IE of PVs and CIEDs is highly dependent on patient preparation and the method used for image interpretation. Based on our results, the best method is to consider a study positive for IE when FDG uptake is present in both AC PET and NAC PET images.

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.

[Positron emission tomography (PET) and PET-CT in renal, bladder and prostate cancer: update]. / La tomografía por emisión de positrones (PET) y PET-TAC en riñón, vías urinarias y próstata: actualización.

PET has demonstrated its utility in management decisions in several types of tumors. In urologic tract tumors and prostate cancer its diagnostic performance has been lower due to the urinary excretion of the radiotracer, which can mask the presence of lesions. However, specific protocols must be applied that improve the diagnostic performance of PET with 18F-FDG in the evaluation of pelvic lesions. Furthermore, prostate cancer is a low-grade tumor with low avidity for 18F-FDG. In spite of these limitations, with PET new and interesting possibilities have been presented. The availability of PET-CT systems has improved its diagnostic performance. On the other hand, the development of new radiotracers that allow targeting other molecular processes and that are metabolized by pathways different to the urinary tract signifies an important advantage compared to 18F-FDG and has evidenced interesting results.

Predictive value of PET-CT for pathological response in stages II and III breast cancer patients following neoadjuvant chemotherapy with docetaxel.

PURPOSE: To prospectively study the value of PET-CT with fluorine-18 fluorodeoxyglucose (FDG) to predict neoadjuvant chemotherapy (NAC) response of locoregional disease of stages II and III breast cancer patients. MATERIAL AND METHODS: A written informed consent and approval were obtained from the Ethics Committee. PET-CT accuracy in the prediction of pathologic complete response (pCR) after NAC was studied in primary tumors and lymph node metastasis in 43 women (mean age: 50 years: range: 27-71 years) with histologically proven breast cancer between December 2009 and January 2011. PET-CT was performed at baseline and after NAC. SUV(max) percentage changes (ΔSUV(max)) were compared with pathology findings at surgery. Receiver-operator characteristic (ROC) analysis was used to discriminate between locoregional pCR and non-pCR. In patients not achieving pCR, it was investigated if ΔSUV(max) could accurately identify the residual cancer burden (RCB) classes: RCB-I (minimal residual disease (MRD)), RCB-II (moderate RD), and RCB-III (extensive RD). RESULTS: pCR was obtained in 11 patients (25.6%). Residual disease was found in 32 patients (74.4%): 16 (37.2%) RCB-I, 15 (35.6%) RCB-II and 2 (4.7%) RCB-III. Sensitivity, specificity, and accuracy to predict pCR were 90.9%, 90.6%, and 90.7%, respectively. Specificity was 94.1% in the identification of a subset of patients who had either pCR or MRD. CONCLUSION: Accuracy of ΔSUV(max) in the locoregional disease of stages II and III breast cancer patients after NAC is high for the identification of pCR cases. Its specificity is potentially sufficient to identify a subgroup of patients who could be managed with conservative surgery.