KP Hwang*, J Yung, RJ Stafford, AM Venkatesan, The University of Texas MD Anderson Cancer Center, Houston, TX

TU-D930-IePD-F9-4 (Tuesday, 7/12/2022) 9:30 AM - 10:00 AM [Eastern Time (GMT-4)]

Exhibit Hall | Forum 9

Purpose: Apparent Diffusion Coefficient (ADC) as measured by diffusion weighted imaging is known to negatively correlate with prostate tumor aggressiveness. Heterogeneity in system and protocol performance causes potential variability in ADC acquired across a large scanner network, prompting a need to evaluate quantitative ADC results in phantom as part of quality assurance (QA). Since ADC varies with temperature, previous studies have performed repeatability and reproducibility assessments with phantoms in an ice water bath to maintain temperature at 0°C. In this study, we employ a model relating ADC to temperature as part of a QA procedure performed at room temperatures to assess reproducibility of ADC measured by our prostate protocols on multiple scanners in our institutional network.

Methods: A diffusion phantom was imaged with our diffusion protocols using 1.5T (n=4) and 3T (n=4) scanners in separate geographical locations (n=4). ROI’s were drawn in all 13 vials of the phantom to produce ADC measurements. Percent difference and coefficient of variation (CV) calculations were performed on ADC measurements normalized to reference values provided by the model at measured phantom temperatures, and compared to the same calculations assuming a fixed temperature of 20°C.

Results: The use of modeled reference values calculated from the measured temperatures did not significantly reduce mean percent difference but brought percent difference together within the tightest range. CV across all measured scanners was reduced from 4.65% to 3.58% when normalized to the temperature model, while CV of the central vial was reduced from 2.87% to 1.30%.

Conclusion: We have developed a QA procedure using a temperature model to assess DWI in a dedicated prostate MRI protocol that obviates the need for strict temperature control. ADC variation due to temperature differences can be corrected using this method, improving measurement of ADC reproducibility across scanners.

Funding Support, Disclosures, and Conflict of Interest: This work was supported by Siemens Healthineers.

Keywords

Diffusion, Quantitative Imaging, Quality Assurance

Taxonomy

IM- MRI : Quantitative Imaging

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