So Yeon Kim MD, Presenter: Nothing to Disclose

Seung Soo Lee MD, Abstract Co-Author: Nothing to Disclose

Ja-Heung Koo, Abstract Co-Author: Nothing to Disclose

Jae Ho Byun MD, Abstract Co-Author: Research Consultant, Bayer AG

Seong Ho Park MD, Abstract Co-Author: Research Consultant, INFINITT Healthcare Co, Ltd

Jeong Kon Kim MD, Abstract Co-Author: Nothing to Disclose

Namkug Kim MS, Abstract Co-Author: Nothing to Disclose

Bum Woo Park, Abstract Co-Author: Nothing to Disclose

Moon-Gyu Lee MD, Abstract Co-Author: Nothing to Disclose

The purpose of our study was to prospectively evaluate apparent diffusion coefficient (ADC) values of hepatic parenchyma and their short-term reproducibility according to the scan methods (breath-hold vs. respiratory-triggered), and ADC calculation methods (two b-values vs. multiple b-values with regression).

Forty-two patients underwent both breath-hold (b factor, 0,50,500 s/mm2) and respiratory-triggered (0,50,300,500,1000 s/mm2) diffusion-weighted imaging (DWI) on an 1.5T MR system twice. The mean ADCs were measured on both right and left hepatic lobe on both breath-hold and respiratory-triggered DWI an the first and second DWI, respectively. ADC values were calculated using two different methods: 1) two b-value method, i.e. using two different b-values and 2) linear regression method, i.e. calculating ADC using linear regression with multiple different b-values. Coefficient of variation (CV) was obtained for assessing the reproducibility of ADC measurement. ADC values and CV were compared according to the scan methods, ADC calculation methods, and ROI locations, using the paired t-test or repeated-measure analysis of variance.

ADC values for respiratory-triggered DWI (1.345-1.904x10-3mm2/sec), two b-value method (1.343-1.904 x10-3mm2/sec), and left hepatic lobe (1.493-2.151 x10-3mm2/sec) were higher than those for breath-hold DWI (1.343-1.651x x10-3mm2/sec), linear regression method(1.345-1.773 x10-3mm2/sec) and right hepatic lobe (1.117-1.658 x10-3mm2/sec), respectively (all P<.001). CV values for respiratory-triggered DWI (6.09-8.56%), linear regression method (6.13-8.48%), and right hepatic lobe (4.62-8.30%) showed tendency toward a better reproducibility than those for breath-hold DWI (8.38-9.92%), two b-value method (6.09-9.92%), and left hepatic lobe (7.19-11.68%), respectively (P=.01-.88).

There are significant differences in ADC values of hepatic parenchyma depending on the scan method, ADC calculation method, and the location of ADC measurement. For more reproducible ADC measurement of hepatic parenchyma, it would be preferred to measure ADC on right hepatic lobe using respiratory-triggered DWI and linear regression method.

The factors affecting the ADC values and the reproducibility should be taken into consideration, when we use ADC values for the diagnosis and longitudinal follow-up of hepatic parenchymal disease.

Kim, S, Lee, S, Koo, J, Byun, J, Park, S, Kim, J, Kim, N, Park, B, Lee, M, Apparent Diffusion Coefficient (ADC) of Hepatic Parenchyma: Factors Affecting ADC Values and Measurement Reproducibility.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9008411.html