BACKGROUND:We wanted to assess whether there was a significant relationship between recruited lung volume (V rec ) and change in density on digital processed chest x-ray measured at 2 different levels of inspiratory plateau pressure corresponding to 2 PEEP levels in patients with acute lung injury or ARDS. METHODS: In 14 subjects, PEEP 5 cm H 2 O and 15 cm H 2 O were prospectively applied in a random order for 10 min. At the end of each period, chest x-ray was taken using a digital portable device, and a pressure-volume curve of the respiratory system was performed. We also assessed P aO 2 , and the static and the dynamic (C dyn,rs ) compliance of the respiratory system. Change in end-expiratory lung volume between tidal breath and relaxation volume of the respiratory system was determined. Radiological attenuation was measured on chest x-rays in 4 regions of interest in the right lung, and in 3 regions of interest in the left lung, drawn in posterior intercostal spaces from top to bottom, by using dedicated software. The ratio of lung density in each region between PEEP 15 and PEEP 5 (rP15/P5) and their arithmetic mean (P15/P5) were computed. V rec was determined from the pressure-volume curves. RESULTS: The median value of rP15/P5 in the 98 lung levels was 0.91 (0.80 -1.01), which was significantly different from 1 (P < .001). The values of rP15/P5 were not significantly different between the lung levels. The median values of V rec and P15/P5 were 288 (173-402) mL and 0.90 (0.80 -0.97), respectively. There was a significant negative correlation between V rec and P15/P5 (R ‫؍‬ ؊0.77, P ‫؍‬ .01). The reduction in P15/P5 tended to correlate with the increase in C dyn,rs (R ‫؍‬ ؊0.49, P ‫؍‬ .077) or in P aO 2 (R ‫؍‬ ؊0.53, P ‫؍‬ .05) between PEEP 15 cm H 2 O and PEEP 5 cm H 2 O. CONCLUSIONS: Digital chest x-ray done at the bedside in acute lung injury/ARDS subjects was able to detect a reduction in density between PEEP 5 cm H 2 O and PEEP 15 cm H 2 O, which correlated with V rec .

Objective: To evaluate the capacity of diffusion-weighted imaging (DWI) to determine the histological grade of small-sized hepatocellular carcinomas (HCCs) in liver cirrhosis in comparison with T 2 weighted imaging. Methods: 51 cirrhotic patients with 63 histologically proven HCCs #2 cm underwent abdominal MRI, including DWI (b-values 50, 400 and 800 s mm 22 ) and T 2 weighted sequences. HCCs were classified into well-differentiated HCCs (n 5 37) and moderately differentiated HCCs (n 5 26). Relative contrast ratios (RCRs) between the lesions and the surrounding liver were performed and compared between the two groups for T 2 weighted images, each b-value and apparent diffusion coefficients (ADCs). A receiver operating characteristic (ROC) analysis was performed to compare RCRs in T 2 and diffusion-weighted images.Results: We found significant differences in RCRs between well-differentiated vs moderately differentiated HCCs for b 5 50, 400 and 800 s mm 22 and T 2 weighted

Objective: To evaluate the correlation between the gastroduodenal artery (GDA) haemodynamic changes and the degree of coeliac axis (CA) stenosis using phasecontrast MRI. Methods: The study was institutional review board approved, and written informed consent was obtained from patients included prospectively. A two-dimensional phase-contrast MRI was performed in 23 patients scheduled for a potential complex supramesocolic surgery, in a plane perpendicular to the GDA, during inspiration and expiration. The peak and mean velocities (V p and V m ), mean flow rate (Q m ) and flow direction at inspiration and at expiration have been correlated with the degree of CA stenosis evaluated by CT. Results: 13 of 23 patients presented CA stenosis due to the median arcuate ligament (34-80% of stenosis), 4 of them had associated atheromatous calcifications. V p , V m and Q m of GDA presented a significant and linear relationship with the degree of CA stenosis, at inspiration as well as at expiration (r . 0.74, p , 0.001). Velocities and flow rates presented a different pattern depending on the degree of CA stenosis: ,34% (n 5 10), flow direction remained physiological with low velocities and flow rates; .60% of stenosis (n 5 5), a reverse flow direction with increased velocities and flow rates were observed; variable patterns between 34% and 60%. Conclusion: Phase-contrast MRI permits the evaluation of haemodynamic changes in GDA induced by CA stenosis, including median arcuate ligament compression, and could be of great interest in therapeutic decision making in supramesocolic surgery, such as liver transplantation or duodenopancreatectomy, by detecting haemodynamically significant stenoses. Advances in knowledge: Physiological phase-contrast MRI detects haemodynamically significant stenoses of the CA by evaluating haemodynamic parameters in the GDA. Physiological phase-contrast MRI demonstrates that flow in the GDA can be a direct marker of the real haemodynamic impact of a CA stenosis on the hepatic vascularization and could thus participate in the presurgical work-up of duodenopancreatectomy or hepatic graft, whereas existing pre-operative imaging are only morphological.