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Rationale: Lung cancer screening using computed tomography (CT) is effective in detecting lung cancer in early stages. Concerns regarding false-positive rates and unnecessary invasive procedures have been raised. Objective: To study the efficiency of a lung cancer protocol using spiral CT and F-18-fluorodeoxyglucose positron emission tomography (FDG-PET). Methods: High-risk individuals underwent screening with annual spiral CTs. Follow-up CTs were done for noncalcified nodules of 5 mm or greater, and FDG-PET was done for nodules 10 mm or larger or smaller (> 7 mm), growing nodules. Results: A total of 911 individuals completed a baseline CT study and 424 had at least one annual follow-up study. Of the former, 14% had noncalcified nodules of 5 mm or larger, and 3.6% had nodules of 10 mm or larger. Eleven non-small cell lung cancers (NSCLC) and one small cell lung cancer (SCLC) were diagnosed in the baseline study (prevalence rate, 1.32%), and two NSCLCs in the annual study (incidence rate, 0.47%). All NSCLCs (92% of prevalence cancers) were diagnosed in stage I (12 stage IA, 1 stage IB). FDG-PET was helpful for the correct diagnosis in 19 of 25 indeterminate nodules. The sensitivity, specificity, positive predictive value, and negative predictive value of FDG-PET for the diagnosis of malignancy were 69, 91, 90, and 71%, respectively. However, the sensitivity and negative predictive value of the screening algorithm, which included a 3-month follow-up CT for nodules with a negative FDG-PET, was 100%. Conclusion: A protocol for early lung cancer detection using spiral CT and FDG-PET is useful and may minimize unnecessary invasive procedures for benign lesions. [ABSTRACT FROM AUTHOR]

Multiple myeloma (MM) is the second most common haematological malignancy and remains incurable despite therapeutic advances. 18 F-FDG (FDG) PET/CT is a relevant tool MM for staging and it is the reference imaging technique for treatment evaluation. However, it has limitations, and investigation of other PET tracers is required. Preliminary results with L-methyl-[ 11 C]- methionine (MET), suggest higher sensitivity than 18 F-FDG. This study aimed to compare the diagnostic accuracy and prognostic value of 1 FDG and MET in MM patients. We prospectively compared FDG and MET PET/CT for assessment of bone disease and extramedullary disease (EMD) in a series of 52 consecutive patients (8 smoldering MM, 18 newly diagnosed MM and 26 relapsed MM patients). Bone marrow (BM) uptake patterns and the detection of focal lesions (FLs) and EMD were compared. Furthermore, FDG PET parameters with known MM prognostic value were explored for both tracers, as well as total lesion MET uptake (TLMU). Median patient age was 61 years (range, 37-83 years), 54% were male, 13% of them were in stage ISS (International Staging System) III, and 31% had high-risk cytogenetics. FDG PET/CT did not detect active disease in 6 patients, while they were shown to be positive by MET PET/CT. Additionally, MET PET/CT identified a higher number of FLs than FDG in more than half of the patients (63%). For prognostication we focussed on the relapsed cohort, due to the low number of progressions in the two other cohorts. Upon using FDG PET/CT in relapsed patients, the presence of more than 3 FLs (HR 4.61, p = 0.056), more than 10 FLs (HR 5.65, p = 0.013), total metabolic tumor volume (TMTV) p50 (HR 4.91, p = 0.049) or TMTV p75 (HR 5.32, p = 0.016) were associated with adverse prognosis. In MET PET/CT analysis, TMTV p50 (HR 4.71, p = 0.056), TMTV p75 (HR 6.27, p = 0.007), TLMU p50 (HR 8.8, p = 0.04) and TLMU p75 (HR 6.3, p = 0.007) adversely affected PFS. This study confirmed the diagnostic and prognostic value of FDG in MM. In addition, it highlights that MET has higher sensitivity than FDG PET/CT for detection of myeloma lesions, including FLs. Moreover, we show, for the first time, the prognostic value of TMTV and TLMU MET PET/CT in the imaging evaluation of MM patients.

The implementation of immunotherapy has radically changed the treatment of oncological patients. Currently, immunotherapy is indicated in the treatment of patients with head and neck tumors, melanoma, lung cancer, bladder tumors, colon cancer, cervical cancer, breast cancer, Merkel cell carcinoma, liver cancer, leukemia and lymphomas. However, its efficacy is restricted to a limited number of cases. The challenge is, therefore, to identify which subset of patients would benefit from immunotherapy. To this end, the establishment of immunotherapy response criteria and predictive and prognostic biomarkers is of paramount interest. In this report, a group of experts of the Spanish Society of Medical Oncology (SEOM), the Spanish Society of Medical Radiology (SERAM), and Spanish Society of Nuclear Medicine and Molecular Imaging (SEMNIM) provide an up-to-date review and a consensus guide on these issues.

11 C-methionine ( 11 C-MET) is a new positron emission tomography (PET) tracer for the assessment of disease activity in multiple myeloma (MM) patients, with preliminary data suggesting higher sensitivity and specificity than 18 F-fluorodeoxyglucose ( 18 F-FDG). However, the value of tumor burden biomarkers has yet to be investigated. Our goals were to corroborate the superiority of 11 C-MET for MM staging and to compare its suitability for the assessment of metabolic tumor burden biomarkers in comparison to 18 F-FDG. Twenty-two patients with newly diagnosed, treatment-naïve symptomatic MM who had undergone 11 C-MET and 18 F-FDG PET/CT were evaluated. Standardized uptake values (SUV) were determined and compared with total metabolic tumor volume (TMTV) for both tracers: total lesion glycolysis (TLG) and total lesion 11 C-MET uptake (TLMU). PET-derived values were compared to Revised International Staging System (R-ISS), cytogenetic, and serologic MM markers such as M component, beta 2 microglobulin (B2M), serum free light chains (FLC), albumin, and lactate dehydrogenase (LDH). In 11 patients (50%), 11 C-MET detected more focal lesions (FL) than FDG ( p < 0.01). SUVmax, SUVmean, SUVpeak, TMTV, and TLMU were also significantly higher in 11 C-MET than in 18 F-FDG ( p < 0.05, respectively). 11 C-MET PET biomarkers had a better correlation with tumor burden (bone marrow plasma cell infiltration, M component; p < 0.05 versus p = n.s. respectively). This pilot study suggests that 11 C-MET PET/CT is a more sensitive marker for the assessment of myeloma tumor burden than 18 F-FDG. Its implications for prognosis evaluation need further investigation.

Current guidelines do not systematically recommend 18F-FDG PET/CT for breast cancer staging; and the recommendations and level of evidence supporting its use in different groups of patients vary among guidelines. This review summarizes the evidence about the role of 18F-FDG PET/CT in breast cancer staging and the therapeutic and prognostic impact accumulated in the last decade. Other related aspects, such as the association of metabolic information with biology and prognosis are considered and evidence-based recommendations for the use of 18F-FDG PET/CT in breast cancer staging are offered. We systematically searched MEDLINE for articles reporting studies with at least 30 patients related to clinical questions following the Problem/Population, Intervention, Comparison, and Outcome framework. We critically reviewed the selected articles and elaborated evidence tables structuring the summarized information into methodology, results, and limitations. The level of evidence and the grades of recommendation for the use of 18F-FDG PET/CT in different contexts are summarized. Level III evidence supports the use of 18F-FDG PET/CT for initial staging in patients with recently diagnosed breast cancer; the diagnostic and therapeutic impact of the 18F-FDG PET/CT findings is sufficient for a weak recommendation in this population. In patients with locally advanced breast cancer, level II evidence supports the use of 18F-FDG PET/CT for initial staging; the diagnostic and therapeutic impact of the 18F-FDG PET/CT findings is sufficient for a strong recommendation in this population. In patients with recently diagnosed breast cancer, the metabolic information from baseline 18F-FDG PET/CT is associated with tumor biology and has prognostic implications, supported by level II evidence. In conclusion, 18F-FDG PET/CT is not recommended for staging all patients with early breast cancer, although evidence of improved regional and systemic staging supports its use in locally advanced breast cancer. Baseline tumor glycolytic activity is associated with tumor biology and prognosis.

Objective: Our aim was to evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) fused with prone 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) in primary tumour staging of patients with breast cancer., Methods: This retrospective study evaluated 45 women with 49 pathologically proven breast carcinomas. MRI and prone PET-CT scans with time-of-flight and point-spread-function reconstruction were performed with the same dedicated breast coil. The studies were assessed by a radiologist and a nuclear medicine physician, and evaluation of fused images was made by consensus. The final diagnosis was based on pathology (90 lesions) or follow-up ≥ 24 months (17 lesions)., Results: The study assessed 72 malignant and 35 benign lesions with a median size of 1.8 cm (range 0.3-8.4 cm): 31 focal, nine multifocal and nine multicentric cases. In lesion-by-lesion analysis, sensitivity, specificity, positive and negative predictive values were 97%, 80%, 91% and 93% for MRI, 96%, 71%, 87%, and 89% for prone PET, and 97%. 94%, 97% and 94% for MRI fused with PET. Areas under the curve (AUC) were 0.953, 0.850, and 0.983, respectively (p < 0.01)., Conclusions: MRI fused with FDG-PET is more accurate than FDG-PET in primary tumour staging of breast cancer patients and increases the specificity of MRI., Key Points: • FDG PET-CT may improve the specificity of MRI in breast cancer staging. • MRI fused with prone 2-[fluorine-18]-fluoro-2-deoxy-D-glucose PET-CT has better overall diagnostic performance than MRI. • The clinical role of fused PET-MRI has not yet been established.

11 C-methionine (MET) has recently emerged as an accurate marker of tumor burden and disease activity in patients with multiple myeloma (MM). This dual-center study aimed at further corroboration of the superiority of MET as positron emission tomography (PET) tracer for staging and re-staging MM, as compared to 18 F-2`-deoxy-2`-fluoro-D-glucose (FDG). 78 patients with a history of solitary plasmacytoma (n=4), smoldering MM (SMM, n=5), and symptomatic MM (n=69) underwent both MET- and FDG-PET/computed tomography (CT) at the University Centers of Würzburg, Germany and Navarra, Spain. Scans were compared on a patient and on a lesion basis. Inter-reader agreement was also evaluated. In 2 patients, tumor biopsies for verification of discordant imaging results were available. MET-PET detected focal lesions (FL) in 59/78 subjects (75.6%), whereas FDG-PET/CT showed lesions in only 47 patients (60.3%; p<0.01), accordingly disease activity would have been missed in 12 patients. Directed biopsies of discordant results confirmed MET-PET/CT results in both cases. MET depicted more FL in 44 patients (56.4%; p<0.01), whereas in two patients (2/78), FDG proved superior. In the remainder (41.0%, 32/78), both tracers yielded comparable results. Inter-reader agreement for MET was higher than for FDG (κ = 0.82 vs κ = 0.72). This study demonstrates higher sensitivity of MET in comparison to standard FDG to detect intra- and extramedullary MM including histologic evidence of FDG-negative, viable disease exclusively detectable by MET-PET/CT. MET holds the potential to replace FDG as functional imaging standard for staging and re-staging of MM., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Background: A major drawback of lung cancer screening programs is the high frequency of false-positive findings on computed tomography (CT). We investigated the accuracy of selective 2-[fluorine-18]-fluoro-2-deoxy-d-glucose (FDG) Positron Emission Tomography/Computed Tomography (PET/CT) scan in assessing radiologically indeterminate lung nodules detected in lung cancer screening., Methods: FDG PET/CT was performed to characterize 64 baseline lung nodules >10mm and 36 incidence nodules detected on low-dose CT screening in asymptomatic current or former smokers (83 men, age range 40-83 years) at high risk for lung cancer. CT images were acquired without intravenous contrast. Nodules were analyzed by size, density, and metabolic activity and visual scored on a 5-point scale for FDG uptake. Nodules were classified as negative for malignancy when no FDG uptake was observed, or positive when focal uptake was observed in the visual analysis, and the maximum standardized uptake value (SUVmax) was measured. Final diagnosis was based on histopathological evaluation or at least 24 months of follow-up., Results: A total of 100 nodules were included. The prevalence of lung cancer was 1%. The sensitivity, specificity, NPV and PPV of visual analysis to detect malignancy were 84%, 95%, 91%, and 91%, respectively, with an accuracy of 91% (AUC 0.893). FDG PET/CT accurately detected 31 malignant tumors (diameters 9-42mm, SUVmax range 0.6-14.2) and was falsely negative in 6 patients. With SUVmax thresholds for malignancy of 1.5, 2, and 2.5, specificity was 97% but sensitivity decreased to 65%, 49%, and 46% respectively, and accuracy decreased to 85%, 79%, and 78% respectively (AUC 0.872)., Conclusions: The visual analysis of FDG PET/CT scan is highly accurate in characterizing indeterminate pulmonary nodules detected in lung cancer screening with low-dose CT. Semi-quantitative analysis does not improve the accuracy of FDG PET/CT over that obtained with a qualitative method for lung nodule characterization., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Purpose: The tumour molecular profile predicts the activity of epidermal growth factor receptor (EGFR) inhibitors in non-small-cell lung cancer (NSCLC). However, tissue availability and tumour heterogeneity limit its assessment. We evaluated whether [(18)F]FDG PET might help predict KRAS and EFGR mutation status in NSCLC., Methods: Between January 2005 and October 2011, 340 NSCLC patients were tested for KRAS and EGFR mutation status. We identified patients with stage III and IV disease who had undergone [(18)F]FDG PET/CT scanning for initial staging. SUVpeak, SUVmax and SUVmean of the single hottest tumour lesions were calculated, and their association with KRAS and EGFR mutation status was assessed. A receiver operator characteristic (ROC) curve analysis and a multivariate analysis (including SUVmean, gender, age and AJCC stage) were performed to identify the potential value of [(18)F]FDG PET/CT for predicting KRAS mutation., Results: From 102 patients staged using [(18)F]FDG PET/CT, 28 (27%) had KRAS mutation (KRAS+), 22 (22%) had EGFR mutation (EGFR+) and 52 (51%) had wild-type KRAS and EGFR profiles (WT). KRAS+ patients showed significantly higher [(18)F]FDG uptake than EGFR+ and WT patients (SUVmean 9.5, 5.7 and 6.6, respectively; p < 0.001). No significant differences were observed in [(18)F]FDG uptake between EGFR+ patients and WT patients. ROC curve analysis for KRAS mutation status discrimination yielded an area under the curve of 0.740 for SUVmean (p < 0.001). The multivariate analysis showed a sensitivity and specificity of 78.6% and 62.2%, respectively, and the AUC was 0.773., Conclusion: NSCLC patients with tumours harbouring KRAS mutations showed significantly higher [(18)F]FDG uptake than WT patients, as assessed in terms of SUVpeak, SUVmax and SUVmean. A multivariate model based on age, gender, AJCC stage and SUVmean might be used as a predictive marker of KRAS mutation status in patients with stage III or IV NSCLC.

Objectives: To investigate quantitative methods of tumor proliferation using 3'-[(18)F]fluoro-3'-deoxythymidine ([(18)F]FLT) PET in patients with breast cancer (BC), studied before and after one bevacizumab administration, and to correlate the [(18)F]FLT-PET uptake with the Ki67 index., Material and Methods: Thirty patients with newly diagnosed, untreated BC underwent a [(18)F]FLT-PET before and 14 days after bevacizumab treatment. A dynamic scan centered over the tumor began simultaneously with the injection of [(18)F]FLT (385 ± 56 MBq). Image derived input functions were obtained using regions of interest drawn on the left ventricle (LV) and descending aorta (DA). Metabolite corrected blood curves were used as input functions to obtain the kinetic Ki constant using the Patlak graphical analysis (time interval 10-60 min after injection). Maximum SUV values were derived for the intervals 40-60 min (SUV40) and 50-60 min (SUV50). PET parameters were correlated with the Ki67 index obtained staining tumor biopsies., Results: [(18)F]FLT uptake parameters decreased significantly (p<0.001) after treatment: SUV50=3.09 ± 1.21 vs 2.22 ± 0.96; SUV40=3.00 ± 1.18 vs 2.14 ± 0.95, Ki&#95;LV(10-3)=52[22-116] vs 38[13-80] and Ki&#95;DA(10-3)=49[15-129] vs 33[11-98]. Consistency interclass correlation coefficients within SUV and within Ki were high. Changes of SUV50 and Ki&#95;DA between baseline PET and after one bevacizumab dose PET correlated with changes in Ki67 index (r-Pearson=0.35 and 0.26, p=0.06 and 0.16, respectively)., Conclusions: [(18)F]FLT-PET is useful to demonstrate proliferative changes after a dose of bevacizumab in patients with BC. Quantification of tumor proliferation by means of SUV and Ki has shown similar results, but SUV50 obtained better results. A correlation between [(18)F]FLT changes and Ki67 index was observed., (Copyright © 2013 Elsevier España, S.L.U. and SEMNIM. All rights reserved.)

Objective: The objective of our study was to investigate whether fluorodeoxyglucose (FDG) positron emission tomography scanning uptake impacts the yield of transbronchial needle aspiration (TBNA)., Methods: We carried out a retrospective analysis of data from 140 consecutive patients (178 lymph nodes) undergoing positron emission tomography-computed tomography scanning and subsequent TBNA with rapid onsite cytologic evaluation of the specimen. Patient and lymph node characteristics, including nodal station, size, FDG uptake, number of passes with the needle, sample adequacy, and the final diagnosis were recorded., Results: The diagnostic yield of TBNA was 75%. Themean short axis lymph node diameter was 18.7±9 mm and mean maximum standardized uptake value (SUVmax) was 7.7±4. The diagnostic yield depended on the lymph node size [odds ratio (OR)=1.07 (1.00-1.14); P=0.04], clinical suspicion of malignancy [OR=5.13 (1.95-13.52); P=0.001], malignant diagnosis [OR=4.91 (1.71-14.09); P=0.003], and FDG uptake [for SUVmax cutoff of 3.0: OR=33.8 (9.2-124); P<0.001]. Only clinical suspicion of cancer [OR=6.2 (2.2-17.2); P=0.001] and FDG uptake [for SUVmax cutoff of 3.0: OR=33.8 (9.2-123.8); P<0.001] remained significant on multivariate analysis. Receiver operating characteristic curves combining 3 key variables (lymph node size, clinical suspicion of malignancy, and SUVmax) showed an area of 0.83 under the curve for a 2.5 SUVmax cutoff and 0.84 for a 3.0 cutoff., Conclusions: FDG uptake is the single most important variable impacting the TBNA yield. TBNA of lymph nodes with an SUVmax less than 3.0 is rarely diagnostic.

Sinonasal mucosal melanoma (MM), although very rare (<1% of the all MM), is second only to squamous cell carcinoma among cancers of the nasal region and still represents a challenging problem in head and neck cancer. A 60-year-old woman had nasal MM stage I, which was treated with concomitant probe-guided tumor excision and an elective neck dissection after sentinel lymph node biopsy. The radioactivity status of the tumor and lymph nodes were compared with the histopathologic specimen. Surgical margins, sentinel lymph node, and lymphadenectomy were free of tumor. The patient was seen in frequent and regular follow-up and was free of disease without any other treatment (radiotherapy, immunotherapy, or chemotherapy). Radioguided surgery is an easy and reproducible surgical technique that could increase the likelihood of adequate excision and minimize the development of nodal disease by performing a "guided" neck dissection after the sentinel lymph node biopsy. A multidisciplinary approach and further studies with a longer follow-up are needed to substantiate the accuracy and safety of this strategy in the treatment of an aggressive neoplasm like MM of the head and neck, which still has a very poor prognosis.

Objective: To determine the feasibility and safety of skeletal myoblast transplantation in patients with chronic myocardial infarction undergoing coronary artery bypass grafting., Methods: Twelve patients with a previous myocardial infarction and ischemic coronary artery disease underwent treatment with coronary artery bypass grafting surgery and intramyocardial injection of autologous skeletal myoblasts cultured with autologous serum. Global and regional cardiac function was assessed by echocardiogram. Fluorine 18 fluorodeoxyglucose and nitrogen 13-ammonia positron emission tomography studies were used to determine cardiac viability and perfusion. A group of historical control patients (n = 14) treated with coronary artery bypass grafting surgery without myoblast transplantation was analyzed., Results: The left ventricular ejection fraction improved from 35.5% +/- 2.3% (mean +/- SEM) before surgery to 55.1% +/- 8.2% at 12 months (P < .01) in the myoblast group and from 33.6% +/- 9.3% to 38.6% +/- 11% in the control group. Regional contractility also improved in the myoblast group, particularly in cardiac segments treated with skeletal myoblasts (wall motion score index: 3.02 +/- 0.17 at baseline vs 1.36 +/- 0.14 at 12 months; P < .0001). Quantitative fluorine 18-fluorodeoxyglucose and nitrogen 13-ammonia positron emission tomography showed an increase in viability and perfusion 12 months after surgery both globally and in segments treated with myoblasts (P = .012 and P = .004). Skeletal myoblast implantation was not associated with adverse events or an increased incidence of cardiac arrhythmias., Conclusions: In patients with previous myocardial infarction, treatment with skeletal myoblasts in conjunction with coronary artery bypass is safe and feasible and is associated with an increased global and regional left ventricular function, improvement in viability, and perfusion of cardiac tissue and no significant incidence of arrhythmias.

Aim: The presence of axillary involvement is the most important prognostic factor in breast cancer. This study analysis the value of 18F-FDG PET in the detection of the lymph node status., Methods: This study includes 200 breast cancer patients. The PET scans were obtained after the injection of 370 MBq of 18F-FDG; the breast areas, axillary, supraclavicular and internal mammary lymph node chains were evaluated. In a subgroup of 100 patients the PET-FDG scan was complemented with the study of the sentinel node (SN) in those cases which did not demonstrate pathological lymph node uptake. The standardized uptake value (SUV) was related to the tumour characteristics of size, histological type, axillary status and histological grading., Results: The sensitivity and specificity of PET-FDG in the detection of axillary involvement was 84.1 and 97.8%, respectively. Seventeen false negative cases were obtained, and were associated with low SUV in the mammary tumour. In 15 cases the PET-FDG scans revealed pathological uptake foci that suggested involvement of the internal mammary chain., Conclusions: The PET-FDG avoids routine SN study in those cases presenting axillary uptake, but it must be complemented by sentinel node study in those cases without pathological uptake. The association of PET-FDG and SN improves the sensitivity in the detection of axillary involvement. Its sensitivity and specificity in the analysis of axillary status can be extended to the evaluation of the internal mammary chain.

Aim: Experimental animal studies suggest that the use of skeletal myoblast in patients with myocardial infarction may result in improved cardiac function. The aim of the study was to assess the feasibility and safety of this therapy in patients with myocardial infarction., Methods and Results: Twelve patients with old myocardial infarction and ischaemic coronary artery disease underwent treatment with coronary artery bypass surgery and intramyocardial injection of autologous skeletal myoblasts obtained from a muscle biopsy of vastus lateralis and cultured with autologous serum for 3 weeks. Global and regional cardiac function was assessed by 2D and ABD echocardiogram. 18F-FDG and 13N-ammonia PET studies were used to determine perfusion and viability. Left ventricular ejection fraction (LVEF) improved from 35.5+/-2.3% before surgery to 53.5+/-4.98% at 3 months (P=0.002). Echocardiography revealed a marked improvement in regional contractility in those cardiac segments treated with skeletal myoblast (wall motion score index 2.64+/-0.13 at baseline vs 1.64+/-0.16 at 3 months P=0.0001). Quantitative 18F-FDG PET studies showed a significant (P=0.012) increased in cardiac viability in the infarct zone 3 months after surgery. No statistically significant differences were found in 13N-ammonia PET studies. Skeletal myoblast implant was not associated with an increase in adverse events. No cardiac arrhythmias were detected during early follow-up., Conclusions: In patients with old myocardial infarction, treatment with skeletal myoblast in conjunction with coronary artery bypass is safe and feasible and is associated with an increased global and regional left ventricular function,improvement in the viability of cardiac tissue in the infarct area and no induction of arrhythmias.

The aim of this article is to present our experience with positron emission tomography (PET) and localized fibrous mesothelioma and to review the literature on this issue. During the past five years we found three patients with a complete clinical history who underwent a CT scan of the thorax and (18)F-fluorodeoxyglucose positron emission tomography ([(18)F]-FDG-PET) and were diagnosed with localized fibrous mesothelioma. Two of the patients were asymptomatic men and the third was a woman with chest pain. The standardized uptake value was 2.1 in one case, and in the other two an absence of FDG uptake was seen. All three had complete resection of the tumor, and in one case the presurgery diagnosis was adenocarcinoma. In one patient the tumor relapsed twice, and the other two patients are alive without any evidence of disease. The value of FDG-PET in the differential diagnosis of pulmonary and pleural abnormalities has gained ground during the last few years. As in most benign tumors, the FDG uptake is usually low (< 2.5) in the localized fibrous mesothelioma. However, more studies are necessary to define the role of FDG-PET in assessing this tumor.

Positron emission tomography (PET) is a new diagnostic technique. It is used to differentiate benign from malignant pulmonary nodules and to detect metastasis and lymph node involvement in primary lung cancer, but little has been published about its possible interest for detection of unknown primary tumors. We report the case of a man who underwent resection of a cerebral tumor. A histological diagnosis of cerebral metastasis from adenocarcinoma with a probable pulmonary origin was made. Preoperative staging (including thoracoabdominal CT-scan and bone scan) did not show any pathologic image, particularly in the thorax. A whole body FDG-PET-scan was then performed. An isolated (1.5 cm of diameter) hypermetabolic focus was discovered in the left upper lobe. Bronchoscopy was normal An upper left lobectomy confirmed the presence of the primary lung adenocarcinoma. In this particular case, FDG-PET proved to be a very useful diagnostic method. New indications are being developed for it.