Hepatic MR Imaging for Differentiation of Biopsy-Proven Steatosis, Iron Deposition, and Combined Disease: One-Dimensional in / Opposed Phase Analysis Vs. Two-Dimensional Computer-Aided Dixon Discrimination
Mustafa Rifaat Bashir¹, Elmar Max Merkle¹, Daniel Tobias Boll^1
1Radiology, Duke University Medical Center, Durham, NC, United States

Steatosis hepatis functions as an inducer of hepatic iron metabolism dysregulation.  MR two-point Dixon T1w imaging with subsequent comprehensive four-phase decomposition analysis facilitated not only metabolite decomposition of intrahepatic lipids and iron ions in steatosis hepatis and hepatic iron overload, but also allowed decomposition of metabolites in combined disease in an in-vivo patient population employing manual as well as computer-aided two-dimensional metabolite discrimination algorithms, with liver biopsy functioning as reference standard.

Simultaneous Measurement of Hepatic Lipid and Iron with High-Speed T2-Corrected Single-Voxel Spectroscopy (HISTO): Analysis of Water-Lipid Compartments
Puneet Sharma¹, Hiroumi D. Kitajima¹, Khalil N. Salman², Bobby Kalb³, Diego R. Martin^3
1Radiology, Emory Healthcare, Atlanta, GA, United States; ²Radiology, Emory University, Atlanta, GA, United States; ³Radiology, Emory University School of Medicine, Atlanta, GA, United States

This investigation analyzes use of a fast T2-corrected MRS method (HISTO) for the simultaneous measurement of hepatic lipid and iron. The multi-echo acquisition allows correction of lipid fraction, while providing R2 measures of water and lipid separately. HISTO was performed in lipid phantoms with variable iron content, and in 3 patients with induced iron susceptibility. It was found that R2-water exhibited strong correlation with iron amount, while R2-lipid showed no dependence, suggesting compartmental division of iron effects. Since imaging evaluates bulk R2*, correlation with iron may be influenced by lipid content. HISTO isolates R2-water and R2-lipid for robust iron assessment.

Preliminary Clinical Experience with a Multiecho 2-Point DIXON (MDIXON) Sequence at 3T as an Efficient Alternative for Both the SAR-Intensive Acquired In- And Out-Of-Phase Chemical Shift Imaging as Well as for 3D Fat-Suppressed T1-Weighted Sequences Used
Thomas G. Perkins¹, Jeremy L. Van Tilburg², Gwenael Herigault³, Holger Eggers⁴, Adri Duijndam³, Gabriele Beck³, Shahid M. Hussain^2,5
1Philips Healthcare, Cleveland, OH, United States; ²The Nebraska Medical Center, Omaha, NE, United States; ³Philips Healthcare, Best, Netherlands; ⁴Philips Research, Hamburg, Germany; ⁵The University of Nebraska Medical Center, Omaha, NE, United States

Body MRI protocols at 3T are often lengthy due to decreased duty cycle, high SAR, and general inefficiencies of the sequences used.  This study (n=22) assessed a new sequence, 2-point mDIXON (mDIXON), which, like the original DIXON, can provide in-phase (IP), out-of-phase (OP), water, and fat images with increased duty cycle and better image quality compared to existing methods. New mDIXON is a more efficient alternative and can replace the existing 2D IP and OP as well as gadolinium-enhanced 3D T1-weighted (eTHRIVE) sequences. The new strategy based on mDIXON will lead to much shorter body MRI exam times at 3T.

Is There an Effect of Gd-EOB-DTPA on Hepatic T2 Signal Intensity and Apparent Diffusion Coefficient?
Hersh Chandarana¹, Ely Felker¹, Bachir Taouli^1,2
1Radiology, NYU Langone Medical Center, New York, NY, United States; ²Radiology, Mount Sinai Medical Center, New York, NY, United States

Gd-EOB-DTPA is recently FDA approved liver-specific contrast agent which has shown potential in liver lesion detection and characterization when delayed (~ 20 min.) post-contrast imaging is performed. However, extending imaging protocol by 20 minutes is not convenient. One approach to decrease imaging time is to perform T2 (T2WI) and diffusion imaging (DWI) after contrast injection between equilibrium and delayed phases of enhancement. In this study, we evaluated effect of Gd-EOB-DTPA on liver and lesion signal intensity on T2WI and DWI and demonstrated minimal effect on liver T2 SI, and no significant change on liver and lesion apparent diffusion coefficient (ADC).

Gd-EOB-DTPA-Enhanced MRI in Cirrhotic Liver in Rats; with Reference to Transporter Activity and Morphological Change of Bile Canaliculi
Natsuko Tsuda¹, Osamu Matsui^2
1Bayer Yakuhin, Ltd, Osaka, Japan; ²Kanazawa University Graduate School of Medical Science, Kanazawa, Japan

The purpose of this study was to analyze the difference of signal intensity on Gd-EOB-DTPA-enhanced MRI between normal and cirrhotic livers in rats in correlation with the expressions of the transporters of Gd-EOB-DTPA and the morphopathological change of bile canaliculi and to discuss the possible mechanisms of the signal profile of Gd-EOB-DTPA-enhanced MRI in cirrhotic livers. As a result, it was found that liver cirrhosis would interfere with the uptake of Gd-EOB-DTPA mediated by oatp1 and promote the elimination of Gd-EOB-DTPA mediated by mrp2. Therefore, the combination of oatp1 down-regulation and mrp2 up-regulation would lead to significant signal loss on Gd-EOB-DTPA-enhanced MRI. In addition to the up-regulation of mrp2, the morphological change in bile canaliculi and microvilli would have an impact on Gd-EOB-DTPA elimination.

Lesion Detectability on T2-Weighted Liver Imaging with Parallel RF Transmission at 3.0 Tesla:  Intraindividual Comparison with Conventional MR Imaging
Guido Matthias Kukuk¹, Juergen Gieseke^1,2, Sebastian Weber¹, Frank Traeber¹, Jan Ullrich¹, Nuschin Morakkabati-Spitz¹, Daniel Thomas¹, Hans Heinz Schild¹, Winfried Albert Willinek^1
1Department of Radiology, University of Bonn, Bonn, NRW, Germany; ²Philips Healthcare, Best, Netherlands

High field MRI has introduced new challenges especially for body imaging with respect to B1 field non-uniformities. Parallel RF transmission allows for more homogeneous excitation, thus improving image quality especially for T2-weighted liver imaging at 3.0 Tesla. Therefore, we evaluated 52 patients in an intraindividual study design to determine the effect of parallel RF transmission on lesion detectability for T2-weighted imaging as compared to conventional MR imaging. Our data demonstrate a significantly higher detection rate of focal liver lesions using parallel RF transmission.

Respiratory Self-Gating for Free-Breathing Abdominal R2* Mapping
Ning Jin¹, Andrew C. Larson^1,2
1Departments of Radiology and Biomedical Engineering, Northwestern University, Chicago, IL, United States; ²Robert H. Lurie Comprehensive Cancer Center, Chicago, IL, United States

Accurate R2* measurements are critical for a wide range of applications. Abdominal R2* mapping requires breath-holding (BH) to avoid respiratory motion artifacts. However, overall spatial resolution and slice coverage is limited by the requisite BH duration. We developed a respiratory self-gated (RSG) imaging strategy for free-breathing abdominal R2* mapping.  The purpose of our study was to compare conventional BH R2* measurements to FB RSG R2* measurements in the liver and kidneys. 3D RSG-mGRE effectively reduced respiratory motion induced artifacts and produced accurate FB R2* maps in the liver and kidneys.

Hemodynamics of Portal Hypertension with 4D Radial Phase Contrast Imaging: Feasibility at 3.0T
Rakhee Wadhwa Verma¹, Kevin Johnson², Benjamin Landgraf¹, Alex Frydrychowicz¹, Christopher J. Francois¹, Oliver Wieben^1,2, Scott B. Reeder^1,2
1Radiology, University of Wisconsin-Madison, Madison, WI, United States; ²Medical Physics, University of Wisconsin-Madison, Madison, WI, United States

Portal hypertension (PHTN) is a secondary complication in patients with cirrhosis and is associated significant morbidity, including varices and variceal bleeding, ascites, and portal venous thrombosis. The purpose of this study is to demonstrate the feasibility of high spatial resolution time resolved 3D radial phase contrast (PC) for evaluation of the hemodynamics of PHTN using a 32-channel phased array coil at 3.0T. The feasibility of comprehensive evaluation of the hemodynamics of PHTN is demonstrated in patients with cirrhosis.