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Thermal Characterization and Initial Imaging Results From the Diffusive Quantitative Imaging Phantom (DQIP)

N Yanasak

N Yanasak1*, X Li2 , M Buzzelli1 , W Randazzo1 , (1) Georgia Regents University, Augusta, GA, (2) Georgia Regents University - Athens, Athens, Georgia


MO-G-18C-9 Monday 4:30PM - 6:00PM Room: 18C

Purpose: The goals of this project were a) to characterize thermal relaxation of the phantom and b) to demonstrate correlations between temperature, signal-to-noise ratio (SNR) and diffusion tensor imaging (DTI) metrics. A site-based clinical DTI protocol was used in this study. The hypothesis is that thermal stability of the phantom will be adequate such that temperature monitoring during a scan may be neglected.

Methods: The Diffusive Quantitative Imaging Phantom (DQIP) is a prototype phantom consisting of fifteen cylindrical compartments containing capillary arrays, encased in a larger compartment. Thermal stability of the phantom was established using a cork container and a Peltier incubator. After the phantom was cooled or heated, thermal relaxation was measured as the phantom was allowed to return to room temperature, with and without cork. A clinical-grade DTI protocol was used to collect scan and temperature-dependent data from the phantom over ten days. SNR and thermal dependences of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were characterized by scanning a heated or cooled phantom over several hours.

Results: The phantom temperature was stable within ±0.08°C/hour per degree difference from the scan room using the cork enclosure, compared to ±0.3°C/hour per degree difference without the cork enclosure. During scanning, temperature variation was ~ 0.1°C/hour. The dependences of (FA, ADC) on (SNR, temperature) were characterized for the heating and cooling experiments. However, for the range of temperature (1.2°C) and SNR (max: ±77%) variations in a particular compartment over all daily measurements, no significant improvement in total variation was achieved after regressing out temperature and SNR, although one compartment showed significant decline after regression.

Conclusion: Thermal stability of the DQIP phantom and incubator system is sufficient for neglecting temperature variations during scanning. For a standard clinical protocol, SNR dependence of FA and ADC are not sufficient to warrant correction.

Funding Support, Disclosures, and Conflict of Interest: Schott Glass North America and The Phantom Laboratory have donated materials and personnel time to this project.

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