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Evaluation of Apparent Diffusion Coefficient Repeatability and Reproducibility for Preclinical MRIs Using
Dariya Malyarenko1, Ghoncheh Amouzandeh1,2, Stephen Pickup3
1Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA.
Abstract:
Relevant to co-clinical trials, the goal of this work was to assess repeatability, reproducibility, and bias of the apparent diffusion coefficient (ADC) for preclinical MRIs using standardized procedures for comparison to performance of clinical MRIs. A temperature-controlled phantom provided an absolute reference standard to measure spatial uniformity of these performance metrics. Seven institutions participated in the study, wherein diffusion-weighted imaging (DWI) data were acquired over multiple days on 10 preclinical scanners, from 3 vendors, at 6 field strengths. Centralized versus site-based analysis was compared to illustrate incremental variance due to processing workflow. At magnet isocenter, short-term (intra-exam) and long-term (multiday) repeatability were excellent at within-system coefficient of variance, wCV [±CI] = 0.73% [0.54%, 1.12%] and 1.26% [0.94%, 1.89%], respectively. The cross-system reproducibility coefficient, RDC [±CI] = 0.188 [0.129, 0.343] µm2/ms, corresponded to 17% [12%, 31%] relative to the reference standard. Absolute bias at isocenter was low (within 4%) for 8 of 10 systems, whereas two high-bias (>10%) scanners were primary contributors to the relatively high RDC. Significant additional variance (>2%) due to site-specific analysis was observed for 2 of 10 systems. Base-level technical bias, repeatability, reproducibility, and spatial uniformity patterns were consistent with human MRIs (scaled for bore size). Well-calibrated preclinical MRI systems are capable of highly repeatable and reproducible ADC measurements.
Insights
Preclinical MRI scanners show excellent repeatability and reproducibility for apparent diffusion coefficient (ADC) measurements. Standardized procedures ensure reliable data comparable to clinical MRI performance.
Area of Science:
- Preclinical Imaging
- Magnetic Resonance Imaging (MRI)
- Quantitative Imaging
Background:
- Co-clinical trials require reliable preclinical MRI data for translation to human studies.
- Assessing the performance of apparent diffusion coefficient (ADC) measurements in preclinical MRI is crucial for standardization.
Purpose of the Study:
- To evaluate the repeatability, reproducibility, and bias of ADC measurements in preclinical MRI systems.
- To compare the performance of preclinical MRI scanners to clinical MRI standards using standardized protocols.
Main Methods:
- Multi-institutional study involving 10 preclinical MRI scanners from 3 vendors across 6 field strengths.
- Utilized a temperature-controlled phantom for absolute reference and spatial uniformity assessment.
- Acquired diffusion-weighted imaging (DWI) data over multiple days, comparing centralized and site-based analysis.
Main Results:
- Excellent short-term (intra-exam) and long-term (multiday) repeatability with within-system coefficient of variance (wCV) of 0.73% and 1.26%, respectively.
- Cross-system reproducibility coefficient (RDC) was 0.188 µm²/ms (17% relative to reference standard).
- Most systems (8/10) exhibited low absolute bias (<4%); two high-bias scanners impacted overall RDC. Site-specific analysis introduced >2% additional variance for 2/10 systems.
Conclusions:
- Well-calibrated preclinical MRI systems demonstrate high repeatability and reproducibility for ADC measurements.
- Performance metrics are comparable to clinical MRI, scaled for bore size, supporting co-clinical trial applications.
- Standardized procedures are essential for minimizing variance and ensuring data integrity in preclinical quantitative MRI.
