PurposeMR elastography (MRE) is a recent non-invasive technique that provides in vivo data on the viscoelasticity of the liver. Since the method is not well established, several different protocols were proposed that differ in results. The aim of the study was to analyze the variability of stiffness measurements in different regions of the liver.MethodsTwenty healthy adults aged 24–45 years were recruited. The examination was performed using a mechanical excitation of 64 Hz. MRE images were fused with axial T2WI breath-hold images (thickness 10 mm, spacing 10 mm). Stiffness was measured as a mean value of each cross section of the whole liver, on a single largest cross section, in the right lobe, and in ROIs (50 pix.) placed in the center of the left lobe, segments 5/6, 7, 8, and the parahilar region.ResultsWhole-liver stiffness ranged from 1.56 to 2.75 kPa. Mean segmental stiffness differed significantly between the tested regions (range from 1.55 ± 0.28 to 2.37 ± 0.32 kPa; P < 0.0001, ANOVA). Within-method variability of measurements ranged from 14 % for whole liver and segment 8–26 % for segment 7. Within-subject variability ranged from 13 to 31 %. Results of measurement within segment 8 were closest to the whole-liver method (ICC, 0.84).ConclusionsStiffness of the liver presented significant variability depending on the region of measurement. The most reproducible method is averaging of cross sections of the whole liver. There was significant variability between stiffness in subjects considered healthy, which requires further investigation.

SummaryBackgroundAtrial fibrillation (AF) is a common supraventricular arrhythmia. ECG-gated MDCT seems to be currently a method of choice for pre-ablation anatomical mapping due to an excellent resolution and truly isotropic three-dimensional nature. The aim of this study was to establish the between-subject variability and inter-observer reproducibility of anatomical evaluation of the pulmonary veins (PV) and the left atrium (LA) using computed tomography.Material/MethodsA retrospective analysis included 42 patients with AF, who were scheduled for a cardiac CT for ablation planning. Images were assessed by two independent radiologists using a semi-automatic software tool. The left atrium anatomy (volume, AP diameter), anatomy of the pulmonary veins (number, ostia diameters and surface area) were evaluated. The relative between-subject variability and the inter-observer variability of measurements were calculated.ResultsThe heart rate during scanning ranged from 50 to 133/min. (mean 79.1/min.) and all examinations were of adequate image quality. Accessory pulmonary veins were found in 24% of patients. Between-subject variability of the PV ostial cross-sectional area ranged from 33% to 48%. The variability of the left atrium size was 21% for the diameter and 35% for the volume. The inter-observer agreement for the detection of accessory pulmonary veins was good (κ=0.73; 95% CI, 0.54–0.93).ConclusionsBetween-subject variability of the pulmonary vein ostial cross-sectional area and the left artial volume is substantial. The anatomical assessment of the pulmonary vein ostia and the left atrium size in computed tomography presents a good inter-observer reproducibility.

SummaryBackgroundRoutine imaging follow-up after endovascular treatment of abdominal aortic aneurysms (EVAR) is mainly aimed at detection of endoleaks. The aim of the study was to assess changes in the size of the abdominal aortic aneurysm sack using CT angiography (CTA) after successful treatment using endovascular stent graft implantation.Material/MethodsA retrospective analysis of CTA results included 102 patients aged 54–88, who had no postoperative complications. Patients underwent CTA before EVAR and after the treatment (mean time between studies, 7.6 months). The largest cross-sectional area of the aneurysm sac was measured using a curved multiplanar reconstruction. A change of the aneurysm cross-sectional over 10% was considered significant.ResultsThe average cross-sectional area decreased after EVAR by 3% and this change was not statistically significant. Regression of the cross-sectional area was observed in 18.6% of patients, progression was in 23.5%, and no change was seen in 57.8%. Cross-sectional areas before and after EVAR were significantly correlated (r=0.75, p<0.0001). There was no correlation between the cross-sectional area change after EVAR and patients’ age or the time between the treatment and the follow-up CTA. Cross-sectional area before the treatment predicted changes in the aneurysm size after EVAR (p=0.0045).ConclusionsRemodeling of abdominal aortic aneurysms after EVAR is not uniform. The change of aneurysm size depends on the initial aneurysm size but not on the time from EVAR. The size of the aneurysm after EVAR should not be considered as a measure of the treatment efficacy.