A fast protocol for multicenter and multiparametric quantitative MRI studies in brain tumor patients using vendor sequences

Background: Multiparametric quantitative MRI (mp-qMRI) provides noninvasive, quantitative measurements sensitive to a variety of tissue properties. In brain tumors (BTs), longitudinal relaxation time (T1), effective transverse relaxation time (T2*), transverse relaxation time (T2), water content (H₂O), and quantitative susceptibility (χ) give valuable insights into the microenvironment. To generate large multicenter datasets, protocols need to be short and implementable on any scanner. The goal of this work was to develop and validate an 8-min, 3T mp-qMRI protocol for BT patients solely using generalized pulse sequences (mGRE and EPI).

Methods: A protocol was developed and tested on a multicompartment phantom, 5 healthy subjects (mean age: 31.64 years), and 4 BT patients (mean age:39.5 years). Phantom and healthy subject longitudinal relaxation time (T1) maps were compared to those obtained using 2 reference methods. The 5 healthy subjects were scanned on 3T MRI scanners at 2 different sites and the reproducibility between scanners was assessed by computing Coefficients of Variance (COV) maps, performing Bland-Altman analysis and t-tests. Clinical feasibility was tested on 4 BT patients.

Results: T1 values obtained using the proposed mp-qMRI protocol agree with those obtained using the reference methods in volunteers (mean error = 8.94 ms). The qMRI maps (T1, T2*, H₂O, and χ) of the volunteers showed good reproducibility between scanners with no significant differences for mean WM and GM qMRI values. WM and GM mean qMRI values agreed well with literature values. H₂O gave the lowest COV and χ maps the highest.

Conclusion: The proposed vendor sequence-based 3T mp-qMRI protocol gives interpolated, high resolution (1 mm isotropic) T1, T2*, H₂O, and $\chi$ maps in 8 min of acquisition.