Imaging of Primary Brain Tumors and Metastases with Fast Quantitative 3-Dimensional Magnetization Transfer

Abstract

Background and purpose: This study assesses whether magnetization transfer (MT) imaging provides additive information to conventional MRI in brain tumors.

Methods: MT data of 26 patients with neoplastic and metastatic brain tumors were analyzed at 1.5 T. For the 3 largest tumor groups investigated in this study--glioblastoma multiforme (GBM), meningiomas, and metastases-statistical comparisons were performed. Analyzed MT parameters included the magnetization transfer ratio (MTR) and 4 quantitative MT parameters (qMT): Relaxation times (T1, T2), exchange rate (kf), and macromolecular content (F). Total imaging time of high-resolution whole brain MTR and qMT imaging with balanced steady-state free precession required 9 minutes. Five ROIs were chosen: Contrast-enhancing (T1W-CE), noncontrast-enhancing (T1W-non-CE), proximal hyperintensity (T2W-pSI), distal hyperintensity (T2W-dSI), and a reference (ref).

Results: Pathologies showed significant (P < .05) MT changes (MTR and qMT) compared to the reference. The T1W-CE, T1W-non-CE, and T2W-pSI ROIs of GBMs, meningiomas, and metastases showed significant differences in MTR and qMT estimates. Similar MTR with significant different qMT values were observed in several ROIs among different lesions. MT maps (MTR and qMT) indicated changes in tissue appearing unaffected on MRI in most glial tumors.

Conclusions: MTR and qMT imaging enables a better differentiation between brain tumors and provides additive information to MRI.

Keywords: Magnetic resonance imaging; magnetization transfer contrast imaging; metastases; neuroimaging; primary brain neoplasms.