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Hersh Chandarana¹, Elizabeth Hecht¹, Bachir Taouli¹, Eric Edward Sigmund¹

¹New York University, New York, New York, USA

Diffusion tensor imaging (DTI) was performed in the kidneys of several healthy volunteers at 3 T, using an echo-planar imaging (EPI) sequence.  Using data from several breathhold acquisitions that were co-registered before processing to improve SNR, robust measures of mean diffusivity (MD) and fractional anisotropy (FA) were obtained in both the cortex and medulla.  Medullary compartments were found to have significantly FA than the cortex, and the principal diffusion eigenvectors were clearly observed to display the expected radial tubular orientation in the medulla.  This study shows the potential for FA and other DTI markers to probe renal microstructure and function.

Philip Martyn Robson¹, Ananth J. Madhuranthakam², Weiying Dai¹, David C. Alsop¹

¹Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; ²GE Healthcare, Boston, Massachusetts, USA

Quantitative perfusion imaging in the kidneys using arterial spin labeling (ASL) is of potential importance for imaging renal function without the use of gadolinium-based contrast agents.  We evaluate strategies for reducing respiratory motion artifacts enabling successful application of ASL in the abdomen.  Background suppression techniques used in ASL, breathing patterns, and retrospective sorting of acquired perfusion-weighted images are explored.  A strategy is established for overcoming the problem of respiratory motion that is suitable for application to clinical populations.  Imaging of volunteers is repeated both within the session and in a separate session to estimate the test-retest repeatability of quantitative renal perfusion imaging using ASL.

Jo V. Hajnal¹, Shaihan J. Malik¹, David J. Larkman¹, Declan O'Regan¹, Kay Nehrke², Ulrich Katscher², Ingmar Graesslin², Peter Börnert²

¹Hammersmith Hospital, Imperial College London, London, UK; ²Philips Research Europe, Hamburg, Germany

We report initial experience with RF shimming on a clinical 3T scanner equipped with a whole body 8 channel  transmit system. Three volunteers were studied. Transmit sensitivity was measured for each coil element on each subject using a multi TR method. Field echo pelvic imaging was then performed using independent drives on each coil optimised to produce a homogeneous transmit field and this was compared to a mode of operation with all elements driven as a single coil. Results showed improved uniformity in excitation, with reduction of regional signal dropout that is common in body imaging at 3T.

Shonit Punwani¹, ², Manuel Rodriguez-Justo², Alan Bainbridge¹, Enrico De Vita¹, ², Rebecca Greenhalgh², Steve Halligan¹, ², Stuart Taylor¹, ²

¹University College London, London, UK; ²University College London Hospital, London, UK

The aim of this study was to correlate in-vivo DCE-MRI parameters with histologically determined mural acute inflammatory change in small bowel resection specimens from patients with known ileal Crohn’s disease. In vivo DCE-MRI of disease affected bowel was performed pre-operation. Post surgical small bowel resection specimens were scanned to enable detailed imaging-histopathology matching. Histological sections were taken through the area of bowel corresponding to the DCE-MRI images and an acute inflammatory score (AIS) derived. AIS was inversely related to semi-quantitative DCE-MRI parameters of enhancement ratio (ERdyn) and slope of enhancement (SoE). This finding is  consistent with the hypothesis of reduced blood flow contributing to histopathological changes in acute Crohn's disease of the small bowel.

Tobias Binser¹, Thomas M. Kessler¹, Chris Boesch¹, Peter Vermathen¹, Harriet C. Thoeny¹

¹University & Inselspital Berne, Berne, Switzerland

The aim of this study was to determine whether DW MRI is able to detect changes in renal diffusion and microperfusion during acute unilateral ureteral obstruction in humans. The results with significantly decreased cortical and medullary perfusion fraction and significantly increased medullary ADC suggest that DW-MRI might provide information as to the degree of obstruction and might therefore help in the decision making of time point of therapeutic intervention. In addition, the results clearly demonstrate the validity and necessity to separate diffusion and microperfusion compartments, in order to prevent misleading findings and interpretations.

Paige Nicole Hopewell¹, Navin Bansal¹

¹Indiana University School of Medicine, Indianapolis, Indiana, USA

Due to excessive motion artifact with ADC calculation from DWI, SQ and MQF 23NaMRI is superior for acute hepatic ischemia evaluation in rats.

senta m. Berggruen¹, dava Grundhoefer, jenny Huang, nancy Hammond¹, paul Nikolaidis¹, frank h. Miller¹

¹Northwestern University, Chicago, Illinois, USA

With the advent of nephrogenic systemic fibrosis (NSF), the new restrictions of gadolinium usage pose an altered approach to MR imaging and interpretation in certain patients. The purpose of this study was to evaluate the accuracy of non-gadolinium enhanced sequences, in conjunction with diffusion-weighted sequences, to differentiate benign from malignant renal lesions. Our preliminary study demonstrates that differentiation of benign from malignant renal lesions and accurate evaluation of renal masses is possible with non-gadolinium enhanced sequences, in conjunction with diffusion-weighted MR imaging. Our data supports that AML have restricted diffusion with lower mean ADC values than renal cell carcinomas.

Adam Charles Braithwaite¹, Brian M. Dale², Daniel T. Boll¹, Elmar M. Merkle¹

¹Duke University Medical Center, Durham, North Carolina, USA; ²Siemens Medical Solutions, Cary, North Carolina, USA

With the emergence of high field strength magnets used in clinical practice, it would be useful to determine if there is any difference in ADC measurements at 3 T compared to the standard 1.5 T. If ADC values are indeed independent of field strength, then the monitoring of tumor response to treatment can be performed at both 1.5 T and 3 T. Our study shows that ADC values in abdominal organs are stable over 5 months but are highly sensitive to changes in post processing or sequences such as those that can occur during routine software upgrades.  Longitudinal studies will need to incorporate some calibration methods to properly compare data across such inevitable changes.  The ADC values in some tissues, such as liver, are sensitive to changes in field strength.  For those tissues care must be taken that follow-up studies are performed at the same field strength.

Anja C.S. Brau¹, Ersin Bayram², Manoj Saranathan³, Akira Kawashima⁴

¹GE Healthcare, Menlo Park, California , USA; ²GE Healthcare, Waukesha, Wisconsin, USA; ³GE Healthcare, Rochester, Minnesota, USA; ⁴Mayo Clinic, Rochester, Minnesota, USA

Three-dimensional coronal abdominal imaging is frequently performed for hepatic and renal imaging applications. However, applying the phase-encoding gradient in the left/right direction renders the acquisition vulnerable to foldover aliasing artifacts that potentially obscure the anatomy of interest. This work demonstrates the utility of a rotated slab excitation (ROSE) scheme for 3D coronal abdominal imaging that significantly reduces the severity of foldover artifacts for improved anatomical visualization with minimal, if any, effect on scan time, spatial resolution, or other imaging parameters.

Nora Frulio¹, Hervé Trillaud¹, Omer Eker¹, Roel Deckers¹, Sebastien Lepreux², Christophe Laurent³, Claire Corot⁴, Chrit Moonen¹, bruno Quesson¹

¹Laboratory IMF, Bordeaux, France; ²CHU Pellegrin, Bordeaux, France; ³CHU Saint André, Bordeaux, France; ⁴Guerbet, Paris, France