Emilien Micard

Chronic Urinary Obstruction: Evaluation of Dynamic Contrast-enhanced MR Urography for Measurement of Split Renal Function

PURPOSE To evaluate if measurement of split renal function ( SRF split renal function ) with dynamic contrast material-enhanced ( DCE dynamic contrast enhanced ) magnetic resonance (MR) urography is equivalent to that with renal scintigraphy ( RS renal scintigraphy ) in patients suspected of having chronic urinary obstruction. MATERIALS AND METHODS The study protocol was approved by the institutional ethics committee of the coordinating center on behalf of all participating centers. Informed consent was obtained from all adult patients or both parents of children. This prospective, comparative study included 369 pediatric and adult patients from 14 university hospitals who were suspected of having chronic or intermittent urinary obstruction, and data from 295 patients with complete data were used for analysis. SRF split renal function was measured by using the area under the curve and the Patlak-Rutland methods, including successive review by a senior and an expert reviewer and measurement of intra- and interobserver agreement for each technique. An equivalence test for mean SRF split renal function was conducted with an α of 5%. RESULTS Reproducibility was substantial to almost perfect for both methods. Equivalence of DCE dynamic contrast enhanced MR urography and RS renal scintigraphy for measurement of SRF split renal function was shown in patients with moderately dilated kidneys (P < .001 with the Patlak-Rutland method). However, in severely dilated kidneys, the mean SRF split renal function measurement was underestimated by 4% when DCE dynamic contrast enhanced MR urography was used compared with that when RS renal scintigraphy was used. Age and type of MR imaging device had no significant effect. CONCLUSION For moderately dilated kidneys, equivalence of DCE dynamic contrast enhanced MR urography to RS renal scintigraphy was shown, with a standard deviation of approximately 12% between the techniques, making substitution of DCE dynamic contrast enhanced MR urography for RS renal scintigraphy acceptable. For severely dilated kidneys, a mean underestimation of SRF split renal function of 4% should be expected with DCE dynamic contrast enhanced MR urography, making substitution questionable.

Comprehensive monitoring of cardiac remodeling with aortic stroke volume values provided by a phase-contrast MRI sequence.

Objectives: Blood pressure (BP) and its changes with antihypertensive therapy are key parameters when monitoring left ventricular (LV) remodeling. This dual cross-sectional and longitudinal MRI study aimed to determine whether this monitoring is enhanced by aortic stroke volume (SV) values provided by a phase-contrast sequence. Methods: The study involved 334 MRI examinations from 247 study participants who had no significant cardiac disease (18–85 years old, 40% with hypertension) and among whom 48 had a 2–4-year MRI follow-up. Left ventricular hypertrophy and concentric geometry were: respectively assessed according to LV mass indexed to body surface area (g/m2) and mass/end-diastolic volume ratio (concentric remodeling index); and correlated with vascular parameters involving BP and the indexed SV (ml/m2) determined in the ascending aorta with a phase-contrast sequence. Results: Stroke volume was highly variable, ranging from 22 to 74 ml/m2. The best cross-sectional correlates were: mean BP × SV product, reflecting cardiac work, for LV mass (r2 = 0.21); and mean BP/SV ratio, reflecting arterial load, for concentric geometry (r2 = 0.29). These two SV-derived parameters led to more than two-fold enhancements in cross-sectional predictions compared with BP parameters alone, whereas their longitudinal changes over time paralleled those of concentric geometry (P = 0.003 for mean BP/SV) and LV mass (P = 0.006 for mean BP × SV), suggesting direct links with cardiac remodeling. Conclusion: The determination of aortic SV with a phase-contrast sequence leads to a significant enhancement in the characterization and monitoring of cardiac remodeling.

HIPPOCAMPUS VOLUMETRY AND VASCULAR DAMAGE IN A COHORT OF OLDER PATIENTS WITH HYPERTENSION: INSIGHTS FROM THE ADELAHYDE STUDY

Objective: Hypertension has been considered as a modifiable risk factor associated with the development of dementia. Various indices of micro- and macro-circulation have been correlated with progressive Alzheimers disease, but little is known about their association with hippocampal atrophy, especially in the early stages of the disease. The aim of this study is to investigate the association between hippocampal volume (HV) and cardiovascular risk factors in a cohort of individuals from the ADELAHYDE, a longitudinal study, investigating the role of vascular factors in the evolution of cognitive functions in a cohort of treated hypertensive patients over 60 years without dementia at inclusion, who were evaluated at inclusion (V1) and after 8 years (V2). Design and method: HV was measured automatically in brain MRIs with Free Surfer Software during V2 in all subjects who have participated to both visits of the ADELAHYDE study. A detailed medical history, somatometric measurements, cognitive tests, leukoraiosis severity (Fazekas score), vascular parameters including pulse wave velocity, central blood pressure and carotid artery plaques,as well as several biochemical parameters were also measured. Results: In the study participated 113 hypertensive patients, 47% male, aged 75.1 ± 5.6 years. At V2 in the multivariate model, male sex (p = 0.009), older age (p = 0.004), lower BMI (p = 0.025), longer duration of hypertension (p = 0.014) and a higher Fazekas score (p = 0.018) and a reduced Cognitive Test Score (p = 0.002), were all independent predictors of lower HV. The total model was able to explain 36.2% of the variation of the hippocampal volume. No association was observed between HV and aortic stiffness of carotid artery geometry. The V1 predictors of lower HV at V2 were older age (p = 0.001), male sex (p = 0.006) and duration of hypertension (p = 0.026). Conclusions: Age, sex, BMI, duration of hypertension, cognitive decline and microvascular cerebral status (leukoaraiosis), were independent factors of HV. Future studies could investigate whether the preventive strategies against these factors could prevent hippocampal atrophy and delay or even reverse the progression and its clinical consequences.

ArchiMed: A Data Management System for Clinical Research in Imaging

Context: There is a great need in clinical research with imaging to collect, to store, to organize and to process large amount of varied data according to legal requirements and research obligations. In practice, many laboratories or clinical research centers working in imaging domain have to manage innumerous images and their associated data without having sufficient IT (Information Technology) skills and resources to develop and to maintain a robust software solution. Since conventional infrastructure and data storage systems for medical image such as “Picture Archiving and Communication System” (PACS) may not be compatible with research needs, we propose a solution: ArchiMed, a complete storage and visualization solution developed for clinical research. Material and methods: ArchiMed is a service oriented server application written in Java EETM which is integrated into local clinical environments (imaging devices, post-processing workstations, others devices...) and allows to safely collect data from other collaborative centers. It ensures all kinds of imaging data storage with a “study centered” approach, quality control and interfacing with mainstream image analysis research tools. Results: With more than 10 millions of archived files for about 4TB stored with 116 studies, ArchiMed, in function for 5 years at CIC-IT of Nancy-France, is used every day by about 60 persons, among whom are engineers, researchers, clinicians and clinical trial project managers.