Partial volume effect estimation and correction in the aortic vascular wall in PET imaging.

We evaluated the impact of partial volume effect (PVE) in the assessment of arterial diseases with (18)FDG PET. An anthropomorphic digital phantom enabling the modeling of aorta related diseases like atherosclerosis and arteritis was used. Based on this phantom, we performed GATE Monte Carlo simulations to produce realistic PET images with a known organ segmentation and ground truth activity values. Images corresponding to 15 different activity-concentration ratios between the aortic wall and the blood and to 7 different wall thicknesses were generated. Using the PET images, we compared the theoretical wall-to-blood activity-concentration ratios (WBRs) with the measured WBRs obtained with five measurement methods: (1) measurement made by a physician (Expert), (2) automated measurement supposed to mimic the physician measurements (Max), (3) simple correction based on a recovery coefficient (Max-RC), (4) measurement based on an ideal VOI segmentation (Mean-VOI) and (5) measurement corrected for PVE using an ideal geometric transfer matrix (GTM) method. We found that Mean-VOI WBRs values were strongly affected by PVE. WBRs obtained by the physician measurement, by the Max method and by the Max-RC method were more accurate than WBRs obtained with the Mean-VOI approach. However Expert, Max and Max-RC WBRs strongly depended on the wall thickness. Only the GTM corrected WBRs did not depend on the wall thickness. Using the GTM method, we obtained more reproducible ratio values that could be compared across wall thickness. Yet, the feasibility of the implementation of a GTM-like method on real data remains to be studied.

[Are there any dosimetric advantages in using VMAT for treatment of locally advanced non-small cell lung cancer?]. / La radiothérapie avec modulation d'intensité rotationnelle apporte-t-elle un avantage dosimétrique dans le traitement du cancer bronchique localement évolué ?

PURPOSE: To analyse the dosimetric differences between the conventional conformal radiation therapy (CR) and the volumetric modulated arc therapy (VMAT) for non-small-cell locally advanced lung cancer (NSCLC). PATIENTS AND METHODS: Two plans (CR and VMAT) were calculated for ten NSCLC patients. Dose to PTV, organs at risk and external contours (body), conformity index (PTV volume/volume of the 95% reference isodose) and homogeneity index ([maximal dose-minimal dose]/dose prescription) were compared. RESULTS: Doses delivered to PTV (homogeneity index, maximal, minimal and mean dose) are similar with both techniques but conformity index is improved by 60% with VMAT: from 0.55±0.07 with CR to 0.89±0.07 with VMAT (P=0.002). Pulmonary protection is improved with VMAT: with CR and VMAT, respectively, the mean lung dose is 14.1±5.2Gy and 12.2±4.5Gy, the lung volume which receives at least 30Gy (V30) is 20±8% and 14±5%, and the V20 is 24±11% and 20±10% (P=0.002). The mean dose received by the body is also 9% lower (P=0.004) and V5 is 13% higher (P=0.004) with VMAT. V10 and V15 were similar with both modalities. From 20Gy and higher, irradiated body volume is larger with CR than with VMAT. The relative difference increases with the dose: from 10% for 20Gy (P=0.014) up to 39% for 62.7Gy (P=0.002). CONCLUSION: Compared to CR, VMAT greatly improves conformity and reduces mean dose and dose delivered from 20Gy and higher to the lungs and the body.

Contribution of CXCR4 and SMAD4 in predicting disease progression pattern and benefit from adjuvant chemotherapy in resected pancreatic adenocarcinoma.

BACKGROUND: Prognosis of patients with pancreatic adenocarcinoma is poor. Many prognostic biomarkers have been tested, but most studies included heterogeneous patients. We aimed to investigate the prognostic and/or predictive values of four relevant biomarkers in a multicentric cohort of patients. PATIENTS AND METHODS: A total of 471 patients who had resected pancreatic adenocarcinoma were included. Using tissue microarray, we assessed the relationship of biomarker expressions with the overall survival: Smad4, type II TGF-ß receptor, CXCR4, and LKB1. RESULTS: High CXCR4 expression was found to be the only independent negative prognostic biomarker [hazard ratio (HR) = 1.74; P < 0.0001]. In addition, it was significantly associated with a distant relapse pattern (HR = 2.19; P < 0.0001) and was the strongest prognostic factor compared with clinicopathological factors. In patients who did not received adjuvant treatment, there was a trend toward decrease in the overall survival for negative Smad4 expression. Loss of Smad4 expression was not correlated with recurrence pattern but was shown to be predictive for adjuvant chemotherapy (CT) benefit (HR = 0.59; P = 0.002). CONCLUSIONS: CXCR4 is a strong independent prognostic biomarker associated with distant metastatic recurrence and appears as an attractive target to be evaluated in pancreatic adenocarcinoma. Negative SMAD4 expression should be considered as a potential predictor of adjuvant CT benefit.

[Value of echography in the diagnosis of post traumatic pathology of the ulnar artery, in manual workers]. / Intérêt de l'échographie dans le diagnostic de la pathologie post traumatique de l'artère cubitale, chez le travailleur manuel.

Three cases of hypothenar hammer syndrome are reported in manual workers who experienced repeated traumatism of the palm of the hand either because of personal habit or the use of professional tools. Hemodynamic examination of the upper limb was performed by plethysmography (Perivein Etna) and Doppler ultrasound (8 MHz) complemented by angiography by direct puncture of the humeral artery. Ultrasonography was performed using a 7.5 MHz probe (Sononranger) for exploration of the ulnar artery at the wrist and in its course through the palm. The 3 patients presented aneurysmal dilatation of the ulnar artery in the palm, complicated by postembolic thrombosis of the collateral arteries of the fingers. The ulnar artery lesion was permeable 1 time, already thrombosed 1 time and thrombosed secondarily 1 time. Ultrasonography of the palm showed suspected aneurysm of the ulnar artery in 2 patients: one case was confirmed by angiography, whereas the other remained only suspect since the thrombosed ulnar artery was not opacified. The third patient presented an ulnar artery thrombosis without true aneurysmal dilatation. It may be concluded that ultrasonography can show suspected aneurysmal dilatation of the ulnar artery and be complementary to arteriography when the ulnar artery is thrombosed.