Uneven distribution of ventilation in acute respiratory distress syndrome

INTRODUCTION: The aim of this study was to assess the volume of gas being poorly ventilated or non-ventilated within the lungs of patients treated with mechanical ventilation and suffering from acute respiratory distress syndrome (ARDS). METHODS: A prospective, descriptive study was performed of 25 sedated and paralysed ARDS patients, mechanically ventilated with a positive end-expiratory pressure (PEEP) of 5 cmH(2)O in a multidisciplinary intensive care unit of a tertiary university hospital. The volume of poorly ventilated or non-ventilated gas was assumed to correspond to a difference between the ventilated gas volume, determined as the end-expiratory lung volume by rebreathing of sulphur hexafluoride (EELV(SF6)), and the total gas volume, calculated from computed tomography images in the end-expiratory position (EELV(CT)). The methods used were validated by similar measurements in 20 healthy subjects in whom no poorly ventilated or non-ventilated gas is expected to be found. RESULTS: EELV(SF6 )was 66% of EELV(CT), corresponding to a mean difference of 0.71 litre. EELV(SF6 )and EELV(CT )were significantly correlated (r(2 )= 0.72; P < 0.001). In the healthy subjects, the two methods yielded almost identical results. CONCLUSION: About one-third of the total pulmonary gas volume seems poorly ventilated or non-ventilated in sedated and paralysed ARDS patients when mechanically ventilated with a PEEP of 5 cmH(2)O. Uneven distribution of ventilation due to airway closure and/or obstruction is likely to be involved

Automatic pericardium segmentation and quantification of epicardial fat from computed tomography angiography

Recent findings indicate a strong correlation between the risk of future heart disease and the volume of adipose tissue inside of the pericardium. So far, large-scale studies have been hindered by the fact that manual delineation of the pericardium is extremely time-consuming and that existing methods for automatic delineation lack accuracy. An efficient and fully automatic approach to pericardium segmentation and epicardial fat volume (EFV) estimation is presented, based on a variant of multi-atlas segmentation for spatial initialization and a random forest classifier for accurate pericardium detection. Experimental validation on a set of 30 manually delineated computer tomography angiography volumes shows a significant improvement on state-of-the-art in terms of EFV estimation [mean absolute EFV difference: 3.8 ml (4.7%), Pearson correlation: 0.99] with run times suitable for large-scale studies (52 s). Further, the results compare favorably with interobserver variability measured on 10 volumes

A comparison of two imaging modalities for detecting lymphatic nodal spread in radiochemotherapy of locally advanced cervical cancer

Background and purpose: In uterine cervical cancer tumour spread reaching the para-aortic lymph nodes is the most significant independent pre-treatment predictor of progression-free survival. When introducing [18F]fluorodeoxyglucose-positron emission tomography (FDG-PET)/computed tomography (CT) in our clinic for patients with advanced cervical cancer planned for definitive radiochemotherapy, the purpose of this study was to quantify to what extent the added information lead to changes in radiotherapy planning. Material and methods: We included 25 consecutive patients with cervical cancer stages IB2 – IIIB planned for definitive radiochemotherapy between November 2010 and May 2012. The patients were examined both with magnetic resonance imaging (MRI) and FDG-PET/CT before treatment and after four weeks of treatment. Results: In 11/24 (46%) of the patients the FDG-PET/CT before treatment provided additional diagnostic information leading to changes in treatment planning compared to information from MRI. Seven of these eleven patients (64%) were alive and without evidence of disease at four-year follow-up. The MRI detected pelvic tumour spread not seen on the FDG-PET/CT in 2/24 patients. The disease-free four-year survival was 59%. Conclusions: Additional diagnostic information from FDG-PET/CT changed treatment strategy in almost half of the patients and may have increased chances of survival in this limited group of patients with locally advanced uterine cervical cancer. We recommend both modalities for nodal detection. Keywords: Cervical cancer, Nodal spread, Radiochemotherapy, FDG-PET/CT, MR