IMPROVEMENT OF BRAIN LESION DETECTION AT 0.1 T BY SIMULTANEOUS USE OFGD-DTPA AND MAGNETIZATION-TRANSFER IMAGING

Imaging parameters were optimized at 0.1 T to improve contrast-to-nois e ratios (CNR) when combining magnetization transfer (MT) imaging and the use of paramagnetic contrast medium. This was accomplished by imag ing a phantom containing serial concentrations of Gd-DTPA in cross-lin ked bovine serum albumin. With the use of simulations, the dependence of CNR on imaging parameters was studied. Conventional and MT images w ere obtained from 10 brain tumor patients with single and triple doses of Gd-DTPA. Simulations demonstrated the importance of TR in postcont rast sequences. The CNR in MT images is less sensitive to TR than in c onventional images. A significant CNR improvement caused by MT remains at longer TR when there is no contrast enhancement without MT. The cl inical results indicate that a single dose of Gd-DTPA combined with MT cannot replace imaging with a triple dose. However, MT significantly improved the CNR after single and triple Gd-DTPA-doses on T-1-weighted and proton-density images.