High field strength magnetic resonance imaging of brain lesion

ABSTRACT

The primary merit of a 3 tesla (T) magnetic resonance (MR) scanner is the increase in the signal-to-noise ratio (SNR). It can offer high spatial and temporal image resolution and its diagnostic potential for brain lesions can be improved at the magnetic strength of 3T. In addition to the increased SNR, strong prolongation of T1 relaxation time at high field MR leads to overall improvements in enhancing lesions versus non-enhancing tissue on contrast-enhanced T1-weighted images and blood versus tissue contrast on time-of-flight MR angiography. Increased chemical shift and susceptibility can improve the spectral resolution in MR spectroscopy and the sensitivities in the micro-hemorrhage detection of gradient echo image, the perfusion change of perfusion MRI, and the blood oxygen level-dependent effect of functional magnetic resonance imaging (MRI). The short acquisition time of diffusion MRI at 3T can decrease motion artifacts in irritable stroke patients and it can be easier to estimate anisotrophy and to increase the efficiency of tractography in diffusion tensor imaging with high numbers of gradient directions. On the other hand, the regulation of the specific absorption rate due to increased radio-frequency energy deposition and the controls for signal loss and increased artifacts at 3T are the main clinical problems. If the drawbacks can be addressed by parallel imaging or pulse sequence changes, 3T MRI can be a useful diagnostic tool and increase the diagnostic accuracy in various brain lesions, such as stroke, trauma, epilepsy, multiple sclerosis, dementia, and brain tumors.