Susan Moyher Noworolski PhD, Presenter: Nothing to Disclose

Maggie Lam MD, Abstract Co-Author: Nothing to Disclose

Michelle Nystrom BSc, Abstract Co-Author: Nothing to Disclose

Bill Chu PhD, Abstract Co-Author: Nothing to Disclose

Linda Ferrell MD, Abstract Co-Author: Nothing to Disclose

Aliya Qayyum MD, Abstract Co-Author: Spouse, Employee, Koninklijke Philips Electronics NV

To compare magnetic resonance spectroscopy (MRS) and opposed-phase (IPOP) MR imaging quantification of liver fat to histopathological steatosis grade at standard and high magnification levels in subjects with non-alcoholic fatty liver disease (NAFLD).

Nineteen healthy volunteers and 26 patients with NAFLD were scanned with MRI and free breathing MRS at 1.5T. Committee on Human Research approval and patient consent were obtained, and compliance with the Health Insurance Portability and Accountability Act was observed. MRS was acquired from an 8cc single voxel using TR/TE=2500ms/30ms, with- (128 acquisitions) and without- (8 acquisitions) water suppression. Respiratory motion artifacts were corrected or removed and lipids to (lipids + unsuppressed water) ratios (L/(L+W)) calculated. IPOP images were acquired with a breathheld dual echo (TE=2.2, 4.4ms) FSPGR sequence. Liver signal intensity loss was measured on IPOP images with 10 (2cm2) ROIs using the spleen as an internal standard. Patients underwent a liver biopsy within a median time of 13 days of imaging (range 0 – 78). Estimates of the steatosis were determined histopathologically using standard clinical grading, with 1) conventional 40x and 100x magnification, and 2) high, 200x and 400x, magnification. Estimates of liver fat based upon MRS L/(L+W) and IPOP MRI were compared to the histopathological fat grade.  

Histopathological steatosis grade was increased in 69% of patients using high magnification levels as compared to conventional. When using high magnification levels, linear correlations versus steatosis grade improved (R2= 0.75 from 0.66 for MRS, 0.85 from 0.84 for IPOP). There was a significant difference in fat estimate intensities among grades for IPOP at both magnification levels and for MRS at high magnification only, p<0.05, Kruskal-Wallis.

Histologic assessment of steatosis appears to vary with level of magnification in subjects with NAFLD and correlation of MRS and IPOP fat estimation is greater with histopathological steatosis grade determined at high magnification levels versus conventional levels.

Correlation of MRS and IPOP MRI liver fat estimation with steatosis grade is greater at high magnification, suggestive of an underestimation of small fat droplets at the standard lower magnification.

Noworolski, S, Lam, M, Nystrom, M, Chu, B, Ferrell, L, Qayyum, A, Estimation of Liver Fat with MRS and MRI: Influence of Magnification Level Used for Histopathologic Grading on Imaging Correlation.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8016714.html