Prospective, intraindividual comparison of MRI versus MDCT for endoleak detection after endovascular repair of abdominal aortic aneurysms

This study compares MRI and MDCT for endoleak detection after endovascular repair of abdominal aortic aneurysms (EVAR). Forty-three patients with previous EVAR underwent both MRI (2D T1-FFE unenhanced and contrast-enhanced; 3D triphasic contrast-enhanced) and 16-slice MDCT (unenhanced and biphasic contrast-enhanced) within 1 week of each other for endoleak detection. MRI was performed by using a high-relaxivity contrast medium (gadobenate dimeglumine, MultiHance). Two blinded, independent observers evaluated MRI and MDCT separately. Consensus reading of MRI and MDCT studies was defined as reference standard. Sensitivity, specificity, and accuracy were calculated and Cohen's k statistics were used to estimate agreement between readers. Twenty endoleaks were detected in 18 patients at consensus reading (12 type II and 8 indeterminate endoleaks). Sensitivity, specificity, and accuracy for endoleak detection were 100%, 92%, and 96%, respectively, for reader 1 (95%, 81%, 87% for reader 2) for MRI and 55%, 100%, and 80% for reader 1 (60%, 100%, 82% for reader 2) for MDCT. Interobserver agreement was excellent for MDCT (k = 0.96) and good for MRI (k = 0.81). MRI with the use of a high-relaxivity contrast agent is significantly superior in the detection of endoleaks after EVAR compared with MDCT. MRI may therefore become the preferred technique for patient follow-up after EVAR

Progression of human carotid and femoral atherosclerosis: a prospective follow-up study by magnetic resonance vessel wall imaging

Aims The time course of atherosclerosis burden in distinct vascular territories remains poorly understood. We longitudinally evaluated the natural history of atherosclerotic progression in two different arterial territories using high spatial resolution magnetic resonance imaging (HR-MRI), a powerful, safe, and non-invasive tool. Methods and results We prospectively studied a cohort of 30 patients (mean age 68.3, n = 9 females) with high Framingham general cardiovascular disease 10-year risk score (29.5%) and standard medical therapy with mild-to-moderate atherosclerosis intra-individually at the level of both carotid and femoral arteries. A total of 178 HR-MRI studies of carotid and femoral arteries performed at baseline and at 1- and 2-year follow-up were evaluated in consensus reading by two experienced readers for lumen area (LA), total vessel area (TVA), vessel wall area (VWA = TVA − LA), and normalized wall area index (NWI = VWA/TVA). At the carotid level, LA decreased (−3.19%/year, P = 0.018), VWA increased (+3.83%/year, P = 0.019), and TVA remained unchanged. At the femoral level, LA remained unchanged, VWA and TVA increased (+5.23%/year and +3.11%/year, both P < 0.01), and NWI increased for both carotid and femoral arteries (+2.28%/year, P = 0.01, and +1.8%/year, P = 0.033). Conclusion The atherosclerotic burden increased significantly in both carotid and femoral arteries. However, carotid plaque progression was associated with negative remodelling, whereas the increase in femoral plaque burden was compensated by positive remodelling. This finding could be related to anatomic and flow differences and/or to the distinct degree of obstruction in the two arterial territorie

Influence des traits des résidus des cultures des couverts sur la disponibilité du phosphore et son acquisition ultérieure par les plantes

International audienceCover crops are typically thought to increase the P nutrition of crops. However, there are mixed reports on this with some studies reporting a negative effect. An improved understanding of cover crop residues and their P release dynamics could offer new insight with the benefit of improved management for optimal P availability in cropping systems. Here, we examined the influence of cover crop residue traits for six different crop types on soil P availability and subsequent plant (ryegrass) P uptake over a four-month period in a soil with moderate P availability. Among the residue traits examined (residue P concentration, N concentration, C:P ratio, C:N ratio, N:P ratio and specific leaf area), only residue P concentration and C:P ratio were related to soil P availability and subsequent crop P uptake. Important short-term effects of residue C:P ratio on P availability were highlighted. Strong to moderate negative correlations between residue C:P ratio and subsequent crop P uptake (R² between 0.4 and 0.8) were observed. Decreases in subsequent crop uptake of up to 43 % compared to unfertilized pots occurred for residues with high C:P ratios for the first cut, strongly suggesting microbial P immobilization. Effects faded with time, with most cover crop residue additions having little to no influence on ryegrass P uptake over a four month period. Residues with the highest C:P ratio nonetheless resulted in a 22 % decrease in cumulative P uptake compared to unfertilized pots. Our study highlighted that cover crop C:P ratio should be managed in order to ensure minimized adverse effects of microbial P immobilization. The observed low effects of cover crop residues on P uptake in a subsequent crop suggest that improving P availability in context with moderate P limitations via cover cropping may require relying on other services provided by cover crops such as mobilization of sparingly available P pools