成人脳の3T磁気共鳴指紋法によるT1およびT2値測定：ファントム検証
Kalina V Jordanova1, Stephen E Ogier1, Stephen E Russek1
1National Institute of Standards and Technology, Boulder, Colorado, USA.
Background:
For clinical implementation of quantitative MRI methods, it is necessary to understand the expected range of nominally healthy tissue properties. Additionally, to compare measurements across MRI systems or provide guidance for clinically meaningful change, these nominally healthy measurements should be completed with phantom validation of the measurement system and method.
Purpose:
To measure T1 and T2 relaxation times on 20 participants using magnetic resonance fingerprinting (MRF) concurrently with phantom measurements for validation.
Methods:
T1 and T2 relaxation times were measured at 3 T using MRF on 20 participants. To assess longitudinal reproducibility, a phantom was scanned in the same session as each in vivo measurement, which resulted in 11 phantom measurements over the 99-day study duration. At each imaging session, phantom and in vivo test-retest measurements were made. Phantom test-retest repeatability was evaluated along with longitudinal reproducibility. Additionally, in vivo test-retest repeatability was evaluated for brain regions of various sizes, and mean in vivo measurements for cerebrospinal fluid (CSF), gray matter (GM), and white matter (WM) are presented.
Results:
Over the study duration, phantom measurements were repeatable and reproducible, and no changes were detected in the MRF measurement of T1 and T2 relaxation times on this system. For in vivo measurements, test-retest variation for CSF, GM, and WM was 2.3%, 0.31%, 0.57% for T1 and 8.3%, 1.9%, 1.3% for T2. We observed that the test-retest variation of T1 and T2 measurements increased as the segmented volume fell below 1 cm3. Mean and standard deviation of T1 and T2 were calculated over all participants for CSF, GM, and WM.
Conclusions:
Phantom measurements characterized the measurement accuracy, repeatability, and reproducibility throughout the study. The MRF T1 and T2 measurements of normal brain tissues at 3 T are validated through concurrent phantom measurements, and mean values were reported for each tissue. This study provides one data point to answer the question of how often phantom quality assessment must be done in tandem with in vivo measurements.
