Ultra High Field MRI

Visualising small brain structures and their functioning has fascinated me since I first discovered functional MRI. Using an ultra-high field scanner (7T) to do so has several advantages. The two most important ones are: (1) the higher signal-to-noise ratio, SNR which is much higher than at lower fields and (2) the stronger BOLD signal.

I study functional responses all over the brain; from the touch of different fingers, to hearing different tones and more abstract concepts such as different time lags. Within the mapped regions (for example for the index finger), I study responses to different types of stimuli (for example touch with a brush versus with a finger).

To optimally benefit from the advantages of 7T, I develop imaging pulse sequences to acquire data either very fast or at very high spatial resolution. I often use specially developed rf-coils to further improve the images. I also work on the characterisation and removal of physiological noise, signal fluctuations caused by breathing and the heartbeat, which are a specific concern at 7T.

I work on improving both the functional imaging and the anatomical data the functional data is mapped onto. One approach is the acquisition of T₁-weighted functional images as intermediate step in the co-registration process. Another is the simultaneous acquisition of quantitative T₁ and T₂^* maps.

Cerebellar imaging at UHF

One of the most challenging brain structures to image (highlighted in yellow) is the cerebellum. The cerebellum, or little brain, is relatively small and has an intricately folded cortex. Because of this fine-scaled anatomy, high resolution is essential in cerebellar imaging.

To distinguish, for example, the somatotopic representations of the fingers in lobules V and VIII, as we did in 2013, millimetre resolution is required. Because of the high degree of cortical folding in the cerebellum, responses to quite different tasks can be found in very nearby regions. Averaging accross subjects further complicates matters. Hence, my research is based on high-resolution data and single-subject analysis. If at all possible, results are visualised on the cerebellar cortex instead of in 3D.

In a recent project with Tomas Knapen, we looked at the involvement of the cerebellum in vision. Although the cerebellum is traditionally thought to be a motor network, there is much recent work that indicates its involvement in a wide range of tasks.

In 2019, I received an NWO Vidi grant to establish a research group in the field of ultra-high field cerebellar imaging, which was further bolstered by an Aspasia grant. In 2022, we returned to live conferences with a flourish. Two prizes for cerebellar presentations were won at the UHF workshop in Lisbon, by Nikos Priovoulos and Emma Brouwer (left). Two poster prizes were won at the ISMRM meeting in London later that spring, by Wietske Zuiderbaan and Nikos Priovoulos (right).