Three-Tesla High-Field Applications

Three-dimensional balanced steady state free precession myocardial perfusion cardiovascular magnetic resonance at 3T using dual-source parallel RF transmission: initial experience

BACKGROUND

The purpose of this study was to establish the feasibility of three-dimensional (3D) balanced steady-state-free-precession (bSSFP) myocardial perfusion cardiovascular magnetic resonance (CMR) at 3T using local RF shimming with dual-source RF transmission, and to compare it with spoiled gradient echo (TGRE) acquisition.

METHODS

Dynamic contrast-enhanced 3D bSSFP perfusion imaging was performed on a 3T MRI scanner equipped with dual-source RF transmission technology. Images were reconstructed using k-space and time broad-use linear acquisition speed-up technique (k-t BLAST) and compartment based principle component analysis (k-t PCA).

RESULTS

In phantoms and volunteers, local RF shimming with dual source RF transmission significantly improved B1 field homogeneity compared with single source transmission (P=0.01). 3D bSSFP showed improved signal-to-noise, contrast-to-noise and signal homogeneity compared with 3D TGRE (29.8 vs 26.9, P=0.045; 23.2 vs 21.6, P=0.049; 14.9% vs 12.4%, p=0.002, respectively). Image quality was similar between bSSFP and TGRE but there were more dark rim artefacts with bSSFP. k-t PCA reconstruction reduced artefacts for both sequences compared with k-t BLAST. In a subset of five patients, both methods correctly identified those with coronary artery disease.

CONCLUSION

Three-dimensional bSSFP myocardial perfusion CMR using local RF shimming with dual source parallel RF transmission at 3T is feasible and improves signal characteristics compared with TGRE. Image artefact remains an important limitation of bSSFP imaging at 3T but can be reduced with k-t PCA.

Integrated intra-operative room design

The design of intraoperative suites require significant inputs from the neurosurgeons. Prior consideration of specific surgical objectives before investment of capital resources will enable to surgeon to yield maximum value from the project. We describe the setup of the integrated neurosurgical centre at our institution which comprises of a hybrid high field MRI suite, an OR's consisting of a multi-slice CT scanner and iso-C 3D respectively. The iCT and ioMRI OR's carry ICG angiography capabilities. These ORs are linked to also the Novalis radiosurgery suites and outpatient clinics and offices to facilitate pre-surgical review, planning as well as treatment plans on a common interface via the BRAINSUITE net.Design considerations include right sit-ing of imaging equipment as well as a focus of ergonomics and design features to maximize workflow. Whenever possible, standard neurosurgical instrumentation is utilized. With widespread availability of technology, neuro-imaging in the operating room may become more prevalent. The surgeon is the lead individual in the team with regards to planning and designing the ORs to accommodate the new imaging equipment.