Effects of DWI Pulse Sequence Parameters and Type On ADC Map Calculation at 3T in a Quantitative MRI Phantom
Presentations
TU-D930-IePD-F9-5 (Tuesday, 7/12/2022) 9:30 AM - 10:00 AM [Eastern Time (GMT-4)]
Exhibit Hall | Forum 9
Purpose: Diffusion weighted imaging (DWI) is commonly employed in MRI as a biomarker for many different pathologies. The apparent diffusion coefficient (ADC) maps generated by DWI sequences are affected by the acquisition parameters and pulse sequence type. This study was performed to compare the effects of using different b-values, inclusion of calculated/synthetic b-values, and pulse sequence on final ADC values in a quantitative prostate MRI phantom with diffusion inserts.
Methods: A standardized prostate MRI phantom with diffusion inserts was scanned on two identical 3T MRI scanners using a 30-channel body receive coil. The seven diffusion inserts were filled with aqueous solutions of polyvinylpyrrolidone (PVP) ranging from 0-50%. DWI images were acquired using standard SS-EPI, RESOLVE, and ZOOMit pulse sequences using four sets of b-values for each sequence: b50/400/800, b50/400/800/calculated 1600, b0/800 and b0/1600. ADC values were measured by drawing a circular ROI over each insert on the ADC map in PACS. Measured ADC values were compared to the ADC derived from a quantitative model of similar PVP solutions measured at 22.5°C and 3T published in previous peer-reviewed literature.
Results: ADC values generated by the ZOOMit sequence were approximately 13% lower than the literature model’s ADC value, while both the RESOLVE and SS-EPI sequences were within ~5% of the literature value. In some inserts, different b-values created variations in ADC measurement in the ZOOMit sequence, with b0/800 and b0/1600 measuring on average 10% difference from b50/400/800/c1600. Including the synthetic b-value in the ADC calculation did not noticeably affect the ADC values in the three DWI sequences tested.
Conclusion: Choice of ZOOMit sequences vs other DWI sequences may affect the final ADC calculation across a range of diffusion values. The magnitude of these ADC variations may be clinically significant for specific indications.
Keywords
Diffusion, Quantitative Imaging, MRI
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