Purpose Simultaneous brain and spinal cord functional MRI is emerging as a new tool to study the central nervous system but is challenging. Poor B0 homogeneity and small size of the spinal cord are principal obstacles to this nascent technology. Here we extend a dynamic shimming approach, first posed by Finsterbusch, by shimming per slice for both the brain and spinal cord. Methods We shim dynamically by a simple and fast optimization of linear field gradients and frequency offset separately for each slice in order to minimize off‐resonance for both the brain and spinal cord. Simultaneous acquisition of brain and spinal cord fMRI is achieved with high spatial resolution in the spinal cord by means of an echo‐planar RF pulse for reduced FOV. Brain slice acquisition is full FOV. Results T2*‐weighted images of brain and spinal cord are acquired with high clarity and minimal observable image artifacts. Fist‐clenching fMRI experiments reveal task‐consistent activation in motor cortices, cerebellum, and C6‐T1 spinal segments. Conclusions High quality functional results are obtained for a sensory‐motor task. Consistent activation in both the brain and spinal cord is observed at individual levels, not only at group level. Because reduced FOV excitation is applicable to any spinal cord section, future continuation of these methods holds great potential.

Purpose Imaging using reduced FOV excitation allows higher resolution or SNR per scan time, but often requires long RF pulses. Here, a recent reduced FOV method that uses a second-order shim gradient to decrease the pulse length, was improved and evaluated for fMRI applications. Theory and Methods The method, initially limited to excite thin disc-shaped regions at isocenter, was extended to excite thicker regions off isocenter, and produced accurate excitation profiles on a grid phantom. Visual stimulation fMRI scans were performed with full and reduced FOV. The resolution of the time-series images and functional activation maps were assessed by the full-width half-maxima of the autocorrelation functions (FACFs) of the noise images and the activation map values, respectively. Results The resolution was higher in the reduced FOV time-series images (4.1 ± 3.7% FACF reduction, P < 0.02) and functional activation maps (3.1 ± 3.4% FACF reduction, P < 0.01), but the SNR was lower (by 26.5 ± 16.9%). However, for a few subjects the targeted region could not be localized to the reduced FOV due to the low Z2 gradient strength. Conclusion Given these results, the authors conclude that the proposed method is feasible, but would benefit from a stronger gradient coil.

Purpose Simultaneous multi-slice (SMS) imaging is a powerful technique that can reduce image acquisition time for anatomical, functional, and diffusion weighted magnetic resonance imaging. At higher magnetic fields, such as 7 Tesla, increased radiofrequency (RF) field inhomogeneity, power deposition, and changes in relaxation parameters make SMS spin echo imaging challenging. We designed an adiabatic 180° Power Independent of Number of Slices (PINS) pulse and a matched-phase 90° PINS pulse to generate a SEmi-Adiabatic Matched-phase Spin echo (SEAMS) PINS sequence to address these issues. Methods We used the adiabatic Shinnar Le-Roux (SLR) algorithm to generate a 180° pulse. The SLR polynomials for the 180° pulse were then used to create a matched-phase 90° pulse. The pulses were sub-sampled to produce a SEAMS PINS pulse-pair and the performance of this pulse-pair was validated in phantoms and in vivo. Results Simulations as well as phantom and in vivo results, demonstrate multi-slice capability and improved B1-insensitivity of the SEAMS PINS pulse-pair when operating at RF amplitudes of up to 40% above adiabatic threshold. Conclusion The SEAMS PINS approach presented here achieves multi-slice spin echo profiles with improved B1-insensitivity when compared to a conventional spin echo.