ESTRO 2023 - Abstract Book

S1854

Digital Posters

ESTRO 2023

0°C. However, due to this being logistically challenging, quality assurance of ADC values at room temperature is appealing. ADC calibration at room temperature was investigated. Materials and Methods The CaliberMRI diffusion phantom contains 0%, 10%, 20%, 30%, 40%, and 50% w/w PVP solutions. The phantom allows integrated room temperature measurements with a novel liquid crystal MR-readable thermometer [1]. NIST-traceable reference ADC values are provided for each solution at 0°C and 16-24°C, so either the phantom thermometer or an ice bath can be used. To compare the two methods, an ice bath scan was performed between two room temperature sessions. Conformance to the QIBA DWI profile is assessed using the central water vial at 0°C. QIBA performance metrics were obtained using qCal- MR software from CaliberMRI and assessed according to the profile specifications.

Results The results of the central water vial at 0°C were within the QIBA DWI profile tolerances. Across ice bath and room temperature scans, bias of the central water vial ranged from and -3.1 to 1.3% and for linearity the slope 95% CI was 0.965, 0.972 (R2 0.998). Applying the QIBA tolerances across all vials, vials with lowest ADC had inferior performance metrics, associated with an increase in artefacts with increasing %PVP. Room temperature measurements of the central water vial showed good accuracy and precision, generally within the QIBA tolerances defined for 0°C, supporting that room temperature ADC calibration is possible.