Abstract
Purpose: To evaluate the impact of field strength and respiratory motion control on diffusion-weighted MR imaging (DWI) of the liver at 1.5 and 3 T. Material and Methods: Three DWI sequences using seven b-values from 20 - 400 s/mm2 were designed with identical parameters but with different handling of respiratory motion [respiratory triggered (RT), free breathing (FB), breath hold (BH)] on 3 T and 1.5 T. Thirteen volunteers were examined at a 3 T and six of them also at a 1.5 T magnet. DW images were analyzed quantitatively and qualitatively. Regions of interest were placed in cranial, middle and caudal parts of the right liver lobe (RLL) and ADC and SNR were calculated. Results: ADC in RLL tended to be lower at 3 T MRI. Least inter-subject ADC variability was found with RT in the middle RLL at 3 T. Highest ADCs were found caudally in the RLL. Significant differences in ADC between middle and caudal RLL were calculated in FB and RT at 3 T and FB and BH at 1.5 T, respectively. No significant difference in SNR was found between 3 T and 1.5 T. There were significantly more artifacts in the left liver lobe (LLL) compared to the RLL in all sequences and in the LLL at 3 T compared to 1.5 T. Conclusion: Our study suggests that longitudinal hepatic ADC measurements should be performed using equivalent field strength, b-values, and acquisition technique, given influence of these factors on ADC measurements.
Highlights
MR imaging is the only method available today which can evaluate the molecular diffusion process in vivo noninvasively
Works conducted in normal subjects comparing the apparent diffusion coefficient (ADC) in the right liver lobe (RLL) on 3 T and 1.5 T have resulted in partly contradictory conclusions, one study observed that the ADC increased at 3 T compared to 1.5 T [11], whereas another study found the ADC to decease at 3 T compared to 1.5 T [12]
For measurement of the apparent diffusion coefficient (ADC) in the liver, three pulse sequences with different strategies for handling of respiratory motion were designed (Table 1): respiratory triggered (RT): A SE-EPI sequence acquired under free breathing with prospective acquisition correction (PACE) navigator respiratory triggering technique
Summary
MR imaging is the only method available today which can evaluate the molecular diffusion process in vivo noninvasively. The potential of DWI has sparked interest in evaluating diffuse and focal liver disease [4], as metabolic, infectious and malignant diseases may involve the liver. Most liver DWI studies have been conducted at 1.5 T. Different DWI techniques, such as breath-hold (BH), respiratory-triggered (RT) or free breathing (FB) [5,6,7,8], were employed. Very few DWI studies were performed at a magnetic field strength of 3 T, either with RT [9] or FB [10]. Works conducted in normal subjects comparing the ADCs in the right liver lobe (RLL) on 3 T and 1.5 T have resulted in partly contradictory conclusions, one study observed that the ADC increased at 3 T compared to 1.5 T [11], whereas another study found the ADC to decease at 3 T compared to 1.5 T [12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
