T 1ρ magnetic resonance fingerprinting

T 1ρ relaxation imaging is a quantitative imaging technique that has been used to assess cartilage integrity, liver fibrosis, tumors, cardiac infarction, and Alzheimer's disease. T 1 , T 2 , and T 1ρ relaxation time constants have each demonstrated different degrees of sensitivity to several markers of fibrosis and inflammation, allowing for a potential multi‐parametric approach to tissue quantification. Traditional magnetic resonance fingerprinting (MRF) has been shown to provide quick, quantitative mapping of T 1 and T 2 relaxation time constants. In this study, T 1ρ relaxation is added to the MRF framework using spin lock preparations. An MRF sequence involving an RF‐spoiled sequence with T R , flip angle, T 1ρ , and T 2 preparation variation is described. The sequence is then calibrated against conventional T 1 , T 2 , and T 1ρ relaxation mapping techniques in agar phantoms and the abdomens of four healthy volunteers. Strong intraclass correlation coefficients (ICC > 0.9) were found between conventional and MRF sequences in phantoms and also in healthy volunteers (ICC > 0.8). The highest ICC correlation values were seen in T 1 , followed by T 1ρ and then T 2 . In this study, T 1ρ relaxation has been incorporated into the MRF framework by using spin lock preparations, while still fitting for T 1 and T 2 relaxation time constants. The acquisition of these parameters within a single breath hold in the abdomen alleviates the issues of movement between breath holds in conventional techniques.