Clinical fMRI: Evidence for a 7T benefit over 3T

Abstract

Despite there being an increasing number of installations of ultra high field MR systems (> 3 T) in clinical environments, no functional patient investigations have yet examined possible benefits for functional diagnostics. Here we performed presurgical localization of the primary motor hand area on 3 T and 7 T Siemens scanners with identical investigational procedures and comparable system specific sequence optimizations. Results from 17 patients showed significantly higher functional sensitivity of the 7 T system measured via percent signal change, mean t-values, number of suprathreshold voxels and contrast to noise ratio. On the other hand, 7 T data suffered from a significant increase of artifacts (ghosting, head motion). We conclude that ultra high field systems provide a clinically relevant increase of functional sensitivity for patient investigations.

Perspectives of Ultra-High-Field MRI in Neuroradiology

“…Some early studies at 7 T could confirm the enhanced SNR during motor tasks [58]. Even single block analyses at 7 T revealed similar or even higher response strength than multi-block measurements at 1.5 T or 3 T. Since those first results, many studies have confirmed the high impact for clinical fMRI at ultra-high field systems [59]. Exact mapping of the somatosensory cortex has been demonstrated at 7 T fMRI leading to the possibility of more dedicated clinical evaluation, for example, pre-surgically [60].…”

Improving Clinical fMRI: Better Paradigms or Higher Field Strength?

“…A first study comparing 3T and 7T motor cortex signals in patients with brain tumors provided promising results: Five of 6 functional parameters indicated improved sensitivity for 7T, even at a standard resolution (1.8 ϫ 1.8 ϫ 3 mm voxel size) and with standard clinical procedures. 4 Corresponding language data (work in progress) achieved with an overt response paradigm that includes various subcomponents of language processing 5 indicate a similar 7T benefit, provided that the artifacts situation can be controlled (Fig 1).…”

“…Improved functional signal strength in a patient with tumor generated by a 7T (Siemens Magnetom) ultra-high-field system within the Wernicke language area (overt speech design, Study Group Clinical fMRI 4 ).…”

基于表面的形态测量学：3t与7t高分辨磁共振结构成像受试者内比较

“…6 A recent study revealed that there was a small difference in the mean cortical thickness among five healthy volunteers between 3T and 7T MRI system. 7 However, the sensitivity of structural imaging on 7T MRI has not been fully investigated.…”

“…However, ultrahigh field strength could also be apt to produce ghosting, head motion artifacts and heterogeneous signal intensity, 6 which could affect the evaluation of subtle structures. There haven't been enough data on using 7T…”