|Talare||Olof Dahlqvist Leinhard|
|Titel||Abdominal quantitative MRI and applications in clinical research|
|Sammanfattning||Quantitative parameter mapping of relaxation times, T1 and T2, and proton density in MRI enables direct comparison of tissue values between different subjects and scans. The possibility to determine values which is observer independent simplifies the design and statistical analysis in clinical studies. During the last years several rapid methods for accurate quantitative imaging of the brain have presented [1,2].
The application of quantitative MR-methods in the abdomen is strongly limited by respiratory motion in combination with the presence of fat tissue. Most MR pulse sequences designed for quantitative parameter mapping suffer from long scan time not compatible with breath hold or respiratory triggering techniques. Furthermore, they usually cannot handle fatty infiltration in the tissue due to the chemical shift offset and the extremely short T1 of the lipids.
In this presentation I will discuss the quantitative MRI-methods used in the on-going liver study, NILB, (the Non-Invasive Liver Biopsy) and the recently published fast food study . For these studies we have developed new imaging techniques based on Dixon imaging where the fat and water signals is acquired in-phase and 180? out-of-phase. For these images new methods for phase sensitive reconstruction , intensity correction  and for removal of the chemical shift artefact have been developed.
In the fast food study the techniques were used in combination with morphon based image segmentation to perform automatic quantification of intra-abdominal and subcutaneous fat tissue . In the NILB-study we use the techniques to perform accurate analysis of dynamic contrast enhanced imaging using the hepatocyte specific contrast agent Gd-EOB-DTPA.
 Warntjes JBM, Dahlqvist O, Lundberg P. A Novel Method for Rapid, Simultaneous T1, T2* and proton density quantification, MRM, 2007 Mar;57(3):528-37.  Warntjes JB, Dahlqvist Leinhard O, West J, Lundberg P. Rapid magnetic resonance quantification on the brain: Optimization for clinical usage. MRM. 2008 Aug;60(2):320-9.  Kechagias S, Ernersson A, Dahlqvist O, Lundberg P, Lindström T, Nystrom FH. Fast-food-based hyper-alimentation can induce rapid and profound elevation of serum alanine aminotransferase in healthy subjects. Gut. 2008 May;57(5):649-54.  Rydell J, Knutsson H, Pettersson J, Johansson A, Farnebäck G, Dahlqvist O, Lundberg P, Nyström F, Borga M. Phase sensitive reconstruction for water/fat separation in MR imaging using inverse gradient. MICCAI'07) Brisbane, Australia, 2007: 10(Pt 1):210-8.  O. Dahlqvist Leinhard, A. Johansson, J. Rydell, Ö. Smedby, F. Nyström, P. Lundberg, M. Borga. Quantitative Abdominal Fat Estimation Using MRI .ICPR?08, FL, USA, 2008.
Lic. Olof Dahlqvist Leinhard is an MR-physicist at Linköping University Hospital and a PhD student at the Dept. of Medical and Health Sciences, Linköping University, on doctoral training at Center for Medical Image Science and Visualization (CMIV) research school. The main focus of his work is to develop new methods for quantitative magnetic resonance imaging and spectroscopy with applications in clinical research projects in neurology, hepatology and obesity research.