MO‐EE‐A4‐01: Stability of T1 Relaxation Time and DCE‐MRI Measures

Abstract

Purpose: With the increased interest in using MR as a means of assessing therapy response, it is important to assess longitudinal systematic variations. In this study, T1 and contrast‐to‐noise ratio (CNR) variations during a dynamic contrast enhanced (DCE) acquisition were assessed on three scanners at three time points. Method and Materials: CNR and T1 measures were calculated from images of a modified Eurospin TO‐5 phantom (DiagnosticSonar, Scotland) consisting of 19 compartments with T1 values ranging from 208–1630 ms. Three GE Excite HD scanners were evaluated. Multiple TI (N=10) inversion recovery (IR), multiple flip angle (N=7) fast spoiled gradient echo (FSPGR), and FSPGR DCE data were acquired at three time points (baseline, 1 hr, 1 week). T1 measurements were obtained using both IR and FSPGR data. CNR measurements were computed using the longest T1 sample as a reference. Correlation and Bland‐Altman repeatability (same scanner) and agreement (different scanners) measures were computed. Results: Correlations of the IR‐ and FSPGR‐based T1 measures were significant for all three scanners (R2>0.996; slopes ranging from 0.84–1.11). Short‐term (1 hr) and one‐week FSPGR repeatability results ranged from 7.0–9.1ms and 10.0–17.4 ms, respectively, with limits of agreement ranging from −15.5–15.1 ms and −21.5–31.7 ms, respectively. The FSPGR BA analyses indicated a linear increase in T1 differences with increasing T1 and the maximum difference was 343 ms. The IR based measurements did not demonstrate such a linear trend and differences were less than 40 ms. Short‐term (1 hr) IR/FSPGR repeatability and limits of agreement results ranged from 91.3–185.1 ms and −330.7–39.5 ms, respectively. Intra‐DCE scan CNR variations ranged from 0.3–0.6% across scanners and time points. Conclusion: The clinical scanners evaluated demonstrate good repeatability of T1 and CNR measurements on a given scanner with larger variations seen between different scanners, even from the same vendor.