Breathhold-regulated Blood Oxygenation Level-dependent (BOLD) MRI of Human Brain at 3 Tesla

Purpose: To investigate the cerebrovascular response to repeated breathhold challenges using blood oxygenation level-dependent (BOLD) MRI at 3T and compare the results with previous data at 1.5T.

Materials And Methods: Six normal volunteers and six patients with brain tumors were recruited for this 3T study. For the normal group, BOLD MRI during repeated breathholds of different durations (five to 30 seconds) were acquired. Maximum signal change, full-width at half-maximum (FWHM) and onset time (defined as the time to the first half-maximum) were determined by curve fitting. The fractional activation volume was also calculated. Patients performed a 10- or 15-second breathhold paradigm according to individual capability.

Results: Significant BOLD signal increases in the gray matter for a breathhold period as short as 5 seconds at 3T, instead of 10 seconds at 1.5T. The fractional activation volume vs. breathhold duration reached a plateau of 49.54 +/- 7.26% at 15 seconds at 3T, which was higher and shorter than that at 1.5T. The maximum signal changes were significantly larger (a 69% increase) at 3T than at 1.5T. In the patient group, there were BOLD signal increases in gray matter but not in tumor bulk or perifocal edema, which agreed with the results previously found at 1.5T.

Conclusion: BOLD MRI at 3T is more sensitive for detecting breathhold-regulated signal changes than at 1.5T, which allows a shorter and more feasible breathhold paradigm for clinical applications in patients with brain tumors.