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Purpose: To study whether volume-based indices of fluorine 18 fluorodeoxyglucose positron emission tomographic (PET)/computed tomographic (CT) imaging is an accurate tool to predict the amount of residual viable tumor after induction chemotherapy in patients with locally advanced non-small cell lung cancer (NSCLC)., Materials and Methods: This study was approved by institutional review board with waivers of informed consent. Twenty-two patients with locally advanced NSCLC underwent surgery after induction chemotherapy. All had pre- and posttreatment FDG PET/CT scans. CT largest diameter, CT volume, maximum standardized uptake value (SUVmax), mean SUV (SUVmean), metabolic tumor volume (TV), and total lesion glycolysis of primary tumor were calculated. Changes in tumor measurements were determined by dividing follow-up by baseline measurement (ratio index). Amounts of residual viable tumor, necrosis, fibrous tissue, inflammatory infiltrate, and Ki-67 proliferative index were estimated on resected tumor. Correlations between imaging indices and histologic parameters were estimated by using Spearman correlation coefficients or Mann-Whitney tests., Results: No baseline or posttreatment indices correlated with percentage of residual viable tumor. TV ratio was the only index that correlated with percentage of residual viable tumor (r = 0.61 [95% confidence interval: 0.24, 0.81]; P = .003). Conversely, SUVmax and SUVmean ratios were only indices correlated with Ki-67 (r = 0.62 [95% confidence interval: 0.24, 0.82]; P = .003; and r = 0.60 [95% confidence interval: 0.21, 0.81]; P = .004, respectively). Total lesion glycolysis ratio was moderately correlated with residual viable tumor (r = 0.53 [95% confidence interval: 0.13, 0.78]; P = .01) and with Ki-67 (r = 0.57 [95% confidence interval: 0.18, 0.80]; P = .006). No ratios were correlated with presence of inflammatory infiltrate or foamy macrophages., Conclusion: TV and total lesion glycolysis ratios were the only indices correlated with residual viable tumor after induction chemotherapy in locally advanced NSCLC.

Background: There is currently little support to understand which pathological factors led to differences in tumor texture as measured from FDG PET/CT images. We studied whether tumor heterogeneity measured using texture analysis in FDG-PET/CT images is correlated with pathological prognostic factors in invasive breast cancer., Methods: Fifty-four patients with locally advanced breast cancer who had an initial FDG-PET/CT were retrospectively included. In addition to SUVmax, three robust textural indices extracted from 3D matrices: High-Gray-level Run Emphasis (HGRE), Entropy and Homogeneity were studied. Univariate and multivariate logistic regression was used to identify PET parameters associated with poor prognosis pathological factors: hormone receptor negativity, presence of HER-2 and triple negative phenotype. Receiver operating characteristic (ROC) curves and the (AUC) analysis, and reclassification measures, were performed in order to evaluate the performance of combining texture analysis and SUVmax for characterizing breast tumors., Results: Tumor heterogeneity, measured with HGRE, was higher in negative estrogen receptor (p = 0.039) and negative progesterone receptor tumors (p = 0.036), and in Scarff-Bloom-Richardson grade 3 tumors (p = 0.047). None of the PET indices could identify HER-2 positive tumors. Only SUVmax was positively correlated with Ki-67 (p<0.0004). Triple negative breast cancer (TNBC) exhibited higher SUVmax (Odd Ratio = 1.22, 95%CI [1.06-1.39],p = 0.004), lower Homogeneity (OR = 3.57[0.98-12.5],p = 0.05) and higher HGRE (OR = 8.06[1.88-34.51],p = 0.005) than non-TNBC. Multivariate analysis showed that HGRE remained associated with TNBC (OR = 5.27[1.12-1.38],p = 0.03) after adjustment for SUVmax. Combining SUVmax and HGRE yielded in higher area under the ROC curves (AUC) than SUVmax for identifying TNBC: AUC =  0.83 and 0.77, respectively. Probability of correct classification also increased in 77% (10/13) of TNBC and 71% (29/41) of non-TNBC (p = 0.003), when combining SUVmax and HGRE., Conclusions: Tumor heterogeneity measured on FDG-PET/CT was higher in invasive breast cancer with poor prognosis pathological factors. Texture analysis might be used, in addition to SUVmax, as a new tool to assess invasive breast cancer aggressiveness.

Objectives: We aimed to assess the clinical value of FDG-PET/CT in patients with ANCA-associated vasculitis., Materials and Methods: We retrospectively included 16 patients with ANCA-associated vasculitis who underwent 21 FDG-PET/CT between 2009 and 2013, in 2 university hospitals from the Paris suburb area. All FDG-PET/CTs were retrospectively analyzed and compared to clinical, biological and conventional imaging data at baseline and during the follow-up., Results: ANCA-associated vasculitis was granulomatosis with polyangiitis (GPA, n=10), microscopic polyangiitis (MPA, n=4), and eosinophilic GPA (EGPA, n=2). PET was performed at initial presentation in 14 cases and during the follow-up in 7 cases. At baseline, PET was positive in 100% of GPA patients (8/8) and in 50% (3/6) of patients with other ANCA-vasculitis (p=0.05). FDG uptake tended to be higher in patients with GPA in comparison to patients with MPA/EGPA (median SUVmax: 5 versus 2.5; p=0.08). Sinonasal, lung, cardio-vascular and kidney involvements were all accurately identified by PET, except in one MPA patient with glomerulonephritis. As expected, skin, joint, eye and peripheral nervous system impairments were not detected by PET. No occult site was detected by PET, except in 2 salivary gland FDG uptake without clinical abnormalities. Patients with GPA exhibited a higher number of positive sites on PET (2 [1.75-2.25] versus 0.5 [0-1], p=0.006) than patients with MPA/EGPA. In pooled data including our study and the literature data of GPA patients (n=31), SUVmax was associated with Birmingham Vasculitis Activity Score (BVAS) (r=0.49; p=0.03)., Conclusion: FDG-PET/CT accurately identifies organ localizations in GPA, other than in nervous system, eye and skin, but do not bring additional benefit to the usual organ screening. The value of FDG-PET/CT in other ANCA-associated vasculitis need to be further addressed., (© 2013.)

Positron emission tomography/computed tomography (PET/CT) is a sensitive method for detecting, staging, and therapy monitoring of many malignancies. It has modified the management of cancer. PET/CT allows for a "whole body" assessment of a metabolic process, depending on the type of tracer, combined with a CT scan. In the present article we review the different PET tracers available today and the most effective applications of PET-CT in oncology, but also in inflammatory diseases, heart diseases and dementia.

Purpose: We sought to determine whether metabolic volume-based measurements on FDG PET/CT scans could provide additional information for predicting outcome in patients with stage III non-small-cell lung cancer (NSCLC) treated with induction chemotherapy., Methods: Included in the study were 32 patients with stage III NSCLC who were treated with induction platinum-based chemotherapy followed in 21 by surgery. All patients had an FDG PET/CT scan before and after the induction chemotherapy. Tumours were delineated using adaptive threshold methods. The SUVmax, SUVpeak, SUVmean, tumour volume (TV), total lesion glycolysis (TLG), and volume and largest diameter on the CT images (CTV and CTD, respectively) were calculated. Index ratios of the primary tumour were calculated by dividing the follow-up measurements by the baseline measurements. The prognostic value of each parameter for event-free survival (EFS) was determined using Cox regression models., Results: The median follow-up time was 19 months (range 6-43 months). Baseline PET and CT parameters were not significant prognostic factors. After induction therapy, only SUVmax, SUVpeak, SUVmean, TV, TLG and CTV were prognostic factors for EFS, in contrast to CTD. Of the index ratios, only TV and TLG ratios were prognostic factors for EFS. Patients with a TLG ratio <0.48 had a longer EFS than those with a TLG ratio >0.48 (13.9 vs. 9.2 months, p = 0.04). After adjustment for the effect of surgical treatment, all the parameters significantly correlated with EFS remained significant., Conclusion: SUV, metabolic volume-based indices, and CTV after induction chemotherapy give independent prognostic information in stage III NSCLC. However, changes in metabolic TV and TLG under induction treatment provide more accurate prognostic information than SUV alone, and CTD and CTV.

Objectives: To assess the accuracy of FDG-PET/CT and MR with diffusion-weighted imaging (MR-DWI) for diagnosing peritoneal carcinomatosis (PC) from gastrointestinal malignancies., Methods: Thirty consecutive patients referred for staging of gastrointestinal malignancy underwent FDG-PET/CT and MR-DWI in this retrospective study. Extent of PC was characterised by dividing the peritoneal cavity into three sites in each patient: right and left supramesocolic areas and inframesocolic level (total 90 sites). Presence of PC was confirmed either by surgery (18/30) or by follow-up (12/30)., Results: PC was confirmed in 19 patients (19/30). At a total of 90 sites, 27 showed proven PC. On a patient-based analysis, sensitivity, specificity, PPV, NPV and accuracy were respectively 84%, 73%, 84%, 73% and 80% for PET/CT and 84%, 82%, 89%, 75% and 83% for MR-DWI. On a site-based analysis, overall sensitivity and specificity of PET/CT (63%, 90%) and MR-DWI (74%, 97%) were not statistically different (P = 0.27). In the supramesocolic area, MR-DWI detected more sites involved than PET/CT (7/9 vs. 4/9). The sensitivities of PET and MR were lower for subcentimetre tumour implants (42%, 50%). Interobserver agreement was very good for PET/CT and good for MR-DWI., Conclusions: FDG-PET/CT and MR-DWI showed similar high accuracy in diagnosing PC. Both techniques underestimated the real extent of PC because of decreased sensitivity for subcentimetre lesions., Key Points: FDG-PET/CT and MR-DWI showed similar high accuracy for diagnosing peritoneal carcinomatosis. • In the supramesocolic area, MR-DWI could be more sensitive than PET/CT. • Both techniques showed lower sensitivity for subcentimetre lesions. • Interobserver agreement was very good for PET/CT and good for MR-DWI.