Journal of magnetic resonance imaging : JMRI · 2025
Contrast-Enhanced MR Fingerprinting With Delta-Relaxometry: Investigating a New Avenue for Tumor Characterization.
СтатьяНаблюдательное исследованиеНазвание и аннотация: Перевод в очереди
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Deng Shengwen, Zhao Walter, Gongala Sree, Sun Jessie E P, Jordan David W, Flask Chris A, Griswold Mark A, Ma Dan, Badve Chaitra
Аннотация
BACKGROUND: MRI contrast agents enhance lesion characterization by altering tissue relaxation properties. However, quantitative assessment of contrast enhancement is limited by variability in contrast administration parameters, and lack of efficient and precise contrast concentration independent relaxivity (r 1, r 2) measurement techniques. MR Fingerprinting (MRF) rapidly, simultaneously and accurately measures T 1 and T 2, enabling for the first time efficient clinical estimation of relaxivity ratios (r 1/r 2).
PURPOSE: To introduce an MRF-derived delta-relaxometry method for mapping contrast-specific relaxivity ratios (r 1/r 2) by accurately measuring ΔR 1/ΔR 2. We hypothesize that delta-relaxometry ratios offer dose-independent, reproducible measures of tissue enhancement, with potential advantages over conventional contrast-enhanced MRI.
STUDY TYPE: Prospective, observational.
POPULATION: Phantom studies and 29 patients (15 glioblastoma, 14 brain metastases).
FIELD STRENGTH/SEQUENCE: 3 T; pre- and post-contrast 3D whole-brain MR Fingerprinting.
ASSESSMENT: Mathematical derivations established a relationship between ΔR 1/ΔR 2 and r 1/r 2. Phantom studies assessed the concentration-dependency of ΔR 1/ΔR 2 compared to ΔT 1 and ΔT 2. Reproducibility was assessed by the inter-subject coefficient of variation (CoV). In vivo tumor type differentiation was assessed with whole-lesion histograms.
STATISTICAL TEST: Coefficient of variation; coefficient of determination; Mann-Whitney U tests with Benjamini-Hochberg correction.
RESULTS: ΔR 1/ΔR 2 is theoretically equivalent to r 1/r 2, showing contrast-dose independence in phantom studies. ΔR 1/ΔR 2 showed no dependence on injected dose or timing (p > 0.05), unlike ΔT 1 and ΔT 2. Delta-relaxometry ratios were highly reproducible, selectively elevated in tumors versus normal tissue, and showed a difference between tumor core and edema (p < 0.05). ΔR 1/ΔR 2 showed higher intra-subject reproducibility (median CoV: GBM = 27.3%, MET = 22.0%) as compared to ΔT 1 (GBM = 57.1%, MET = 106.2%; p < 0.001). Whole-lesion histogram analysis of delta-relaxometry ratios demonstrated GBM versus metastasis differentiation (p < 0.05). "DATA" CONCLUSIONS: In this proof-of-concept study, MRF-derived ΔR 1/ΔR 2 ratios show potential for reproducible, clinically feasible, dose-independent relaxivity quantification. Delta-relaxometry ratios may offer a novel approach to tissue characterization with minimal background enhancement, distinct from perfusion imaging. Our results suggest delta-relaxometry as a tumor imaging marker worthy of further investigation.
EVIDENCE LEVEL: 3 (retrospective cohort study with imperfectly applied reference standard).
TECHNOLOGY EFFICACY: 1 (feasibility study with quantitative assessment, requires a comparison with standard of care).
PURPOSE: To introduce an MRF-derived delta-relaxometry method for mapping contrast-specific relaxivity ratios (r 1/r 2) by accurately measuring ΔR 1/ΔR 2. We hypothesize that delta-relaxometry ratios offer dose-independent, reproducible measures of tissue enhancement, with potential advantages over conventional contrast-enhanced MRI.
STUDY TYPE: Prospective, observational.
POPULATION: Phantom studies and 29 patients (15 glioblastoma, 14 brain metastases).
FIELD STRENGTH/SEQUENCE: 3 T; pre- and post-contrast 3D whole-brain MR Fingerprinting.
ASSESSMENT: Mathematical derivations established a relationship between ΔR 1/ΔR 2 and r 1/r 2. Phantom studies assessed the concentration-dependency of ΔR 1/ΔR 2 compared to ΔT 1 and ΔT 2. Reproducibility was assessed by the inter-subject coefficient of variation (CoV). In vivo tumor type differentiation was assessed with whole-lesion histograms.
STATISTICAL TEST: Coefficient of variation; coefficient of determination; Mann-Whitney U tests with Benjamini-Hochberg correction.
RESULTS: ΔR 1/ΔR 2 is theoretically equivalent to r 1/r 2, showing contrast-dose independence in phantom studies. ΔR 1/ΔR 2 showed no dependence on injected dose or timing (p > 0.05), unlike ΔT 1 and ΔT 2. Delta-relaxometry ratios were highly reproducible, selectively elevated in tumors versus normal tissue, and showed a difference between tumor core and edema (p < 0.05). ΔR 1/ΔR 2 showed higher intra-subject reproducibility (median CoV: GBM = 27.3%, MET = 22.0%) as compared to ΔT 1 (GBM = 57.1%, MET = 106.2%; p < 0.001). Whole-lesion histogram analysis of delta-relaxometry ratios demonstrated GBM versus metastasis differentiation (p < 0.05). "DATA" CONCLUSIONS: In this proof-of-concept study, MRF-derived ΔR 1/ΔR 2 ratios show potential for reproducible, clinically feasible, dose-independent relaxivity quantification. Delta-relaxometry ratios may offer a novel approach to tissue characterization with minimal background enhancement, distinct from perfusion imaging. Our results suggest delta-relaxometry as a tumor imaging marker worthy of further investigation.
EVIDENCE LEVEL: 3 (retrospective cohort study with imperfectly applied reference standard).
TECHNOLOGY EFFICACY: 1 (feasibility study with quantitative assessment, requires a comparison with standard of care).