Pulsed off-resonance magnetization transfer for brain tumor in patients

We investigated the clinical applicability of pulsed off-resonance magnetization transfer (MT) technique in magnetic resonance (MR) imaging for the estimation of the histological feature of brain tumor. The parameters were optimized using bovine serum albumin (BSA) solutions and gels in 1.5-tesla MR system as follows: TR, 50 msec; TE, 5 msec; flip angle, 30 degree; offset frequency, 1000 Hz. MT effect was evaluated by measuring the MT ratio (MTR) and reconstructing calculated MTR color image. The MTRs of the BSA solutions and gels increased with increasing concentrations of protein, while the MTRs of the gels were remarkably higher than those of the solutions. The optimized sequence was performed in 20 healthy volunteers and 30 patients with brain tumors. In normal brains, the MTRs were significantly higher in white matter than in gray matter (p < 0.05). The MTR in brain tumor was significantly lower than that in normal brain tissue (p < 0.05) and the calculated MTR image produced contrast between brain tumor and normal brain tissue. There was a statistically significant difference in MTR between benign (0.30 +/- 0.05, n = 17) and malignant (0.26 +/- 0.04, n = 13) tumors (p < 0.05). The optimized MT technique is quite sensitive for estimating the degree of intermolecular interaction between macromolecules and water within the central nervous system.