Traditional Posters: Body Imaging

Gavin Hamilton¹, Michael S. Middleton¹, Takeshi Yokoo¹, Masoud Shiehmorteza¹, Claude B. Sirlin<sup>1

1</sup>Department of Radiology, University of California, San Diego, San Diego, CA, United States

We examined the repeatability of the liver fat fraction given by MR Spectroscopy. We measured the fat fraction at 3T in vivo by collecting five single average STEAM spectra at progressively longer of TEs of 10, 15, 20, 25 and 30 ms in a single breath-hold to generate T2 and T2-corrected peak areas. We repeated this measurement three times per subject and showed this method produced highly repeatable liver fat fraction and water T2 estimates. This method did not produce a repeatable estimate of fat T2.

2641. On the Evaluation of 31P MRS Human Liver Protocols.

Mikael F. Forsgren¹, Olof Dahlqvist Leinhard^2,3, Bengt Norén⁴, Stergios Kechagias, Fredrik H. Nyström, Örjan Smedby^2,3, Peter Lundberg, <sup>3,4

1</sup>Linköping University; ²Faculty of Health Sciences/IMH, Linköping University, Linköping, Sweden; ³Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden; ⁴Radiology, Linköping University Hospital

In this study the effect of proton decoupling, nuclear overhauser enhancement and repetition time was investigated in 31P liver MRS at 1.5T. An optimal protocol was determined and validate on 13 healthy volunteers.

2642. Reproducibility Evaluation of Liver Metabolite Parameters: ¹H Decoupled - ³¹P MRSI of Normal Volunteers at 1.5T

Jing Qi¹, Amita Shukla-Dave¹, Jason Koutcher¹, Mithat Gönen², Yuman Fong³, Lawrence H. Schwartz⁴, Kristen L. Zakian<sup>5

1</sup>Medical Physics, Memorial Sloan-Kettering Cancer Center; ²Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center; ³Surgery, Memorial Sloan-Kettering Cancer Center; ⁴Radiology, Sloan-Kettering Cancer Center; ⁵Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, United States

In order to evaluate reproducibility of liver metabolites measured by ¹H decoupled-³¹P MRSI technique, 13 normal subjects were investigated twice at 2 weeks interval. Concentration of PE, PC, PME, Pi, GPE, GPC, PDE and NTP were calculated. Inter- and intra- subject variations were analyzed. Inter- and intra-subject coefficient variation ranged from 11% to 25 % for all metabolite concentration. Intra-subject reproducibility was not superior to inter-subject reproducibility, indicating that the random biological differences don’t seem to exceed the differences generated by technical variation in normal volunteers. Both technical and biological factors should be considered when interpret liver ³¹P MRSI data.

2643. Comparison of Two Strategies to Improve Quality of in Vivo 1H MR Spectra in the Presence of Motion

Michael Germuska¹, Jian Xu², Martin Leach¹, Geoffrey Payne<sup>1

1</sup>CR-UK and EPSRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden Hospital, Sutton, London, United Kingdom; ²Siemens Healthcare U.S., New York, NY, United States

In vivo 1H MR spectroscopy has proved valuable for evaluating tumours. However, acquisition of spectra in the abdomen is complicated by respiratory motion. The motion degrades the spectral quality by phase and frequency distortions and by modification of the PSF. We compared two approaches to combat motion in liver spectroscopy. The first utilises a post-processing approach to correct phase and frequency distortions, the second employs prospective gating when acquiring the data. Both techniques showed an improvement in linewidth and SNR compared to free-breathing acquisitions. The post-processing methodology showed an advantage in SNR due to the increased number of signal averages.

2644. Ω-3 Fatty Acid Detection by L-COSY in Human Bone Marrow at 3T

Saadallah Ramadan¹, Robert V. Mulkern², Carolyn E. Mountford<sup>1

1</sup>Radiology, Brigham and Women's Hospital, Boston, MA, United States; ²Radiology, Children’s Hospital, Boston, MA, United States

3 is an essential fatty acid (FA) that cannot be synthesized in the body and is obtained by diet. In the human body, essential FA serve multiple functions including neuroprotective functions, mood, behavior and prevents inflammation. There are two types of £s-3 FAs: eicosapentaenoic acid (EPA) docosahexaenoic acid (DHA), both of these molecular structures end with R-HC=CH-CH2-CH3. We investigated possibility of detecting ƒç-3 in human bone marrow, at 3T, using localised one dimensional (1D) (PRESS) and localized two-dimensional (2D) correlation spectroscopy (L-COSY).