Angiotensin-converting enzyme inhibitor-enhanced MR renography: repeated measures of GFR and RPF in hypertensive patients.

This study aims to assess the feasibility of a protocol to diagnose renovascular disease using dual MR renography acquisitions: before and after administration of angiotensin-converting enzyme inhibitor (ACEi). Results of our simulation study aimed at testing the reproducibility of glomerular filtration rate (GFR) and renal plasma flow demonstrate that for a fixed overall dose of 12 ml gadolinium-based contrast material (500 mmol/l), the second dose should be approximately twice as large as the first dose. A three-compartment model for analyzing the second-injection data was shown to appropriately handle the tracer residue from the first injection.

Cognition in healthy aging is related to regional white matter integrity, but not cortical thickness.

It is well established that healthy aging is accompanied by structural changes in many brain regions and functional decline in a number of cognitive domains. The goal of this study was to determine (1) whether the regional distribution of age-related brain changes is similar in gray matter (GM) and white matter (WM) regions, or whether these two tissue types are affected differently by aging, and (2) whether measures of cognitive performance are more closely linked to alterations in the cerebral cortex or in the underlying WM in older adults (OA). To address these questions, we collected high-resolution magnetic resonance imaging (MRI) data from a large sample of healthy young adults (YA; aged 18-28) and OA (aged 61-86 years).

Body and cardiovascular MR imaging at 3.0 T.

Potential advantages of magnetic resonance (MR) imaging at 3 T include higher signal-to-noise ratios, better image contrast, particularly in gadolinium-enhanced applications, and better spectral separation for spectroscopic applications. In terms of clinical imaging, these advantages can mean higher-spatial-resolution images, faster imaging, and improved MR spectroscopy. However, achieving superior imaging and spectroscopic quality at 3 T can be challenging.

Renal function measurements from MR renography and a simplified multicompartmental model.

The purpose of this study was to determine the accuracy and sources of error in estimating single-kidney glomerular filtration rate (GFR) derived from low-dose gadolinium-enhanced T1-weighted MR renography. To analyze imaging data, MR signal intensity curves were converted to concentration vs. time curves, and a three-compartment, six-parameter model of the vascular-nephron system was used to analyze measured aortic, cortical, and medullary enhancement curves.