High resolution MRI of the brain at 4.7 Tesla using fast spin echo imaging

Abstract

Over recent years, high field MR scanners (3 T and above) have become increasingly widespread due to potential advantages such as higher signal-to-noise ratio. However, few examples of high resolution images covering the whole brain in reasonable acquisition times have been published to date and none have used fast spin echo (FSE), a sequence commonly employed for the acquisition of T(2) weighted images at 1.5 T. This is mostly due to the increased technical challenges associated with uniform signal generation and the increasingly restrictive constraints of current safety guidelines at high field. We investigated 10 volunteers using an FSE sequence optimized to the 4.7 T environment. This sequence allows the acquisition of 17- and 34-slice data sets with an in-plane resolution of approximately 500 microm x 500 microm and a slice thickness of 2 mm, in 5 min 40 s and 11 min 20 s, respectively. The images appear T(2) weighted, although the contrast is due to the combined effects of chosen echo time, magnetization transfer, direct radio frequency saturation and diffusion as well as the T(1) and T(2) relaxation times of the tissue. The result is an excellent detailed visualization of anatomical structures, demonstrating the great potential of 4.7 T MRI for clinical applications. This paper shows that, with careful optimization of sequence parameters, FSE imaging can be used at high field to generate images with high spatial resolution and uniform contrast across the whole brain within the prescribed power deposition limits.

Fatal newborn head enlargement: high resolution magnetic resonance imaging at 4.7 T

“…1 The resulting T 2 weighted images confirmed the clinical diagnosis of subgaleal haemorrhage. In addition to uncal and transtentorial herniation, haemorrhagic infarction involving deep grey matter, cerebellum, and spinal cord were observed (fig 1).…”

Potential role of high‐field MRI for studies in Parkinson's disease

“…MRI studies at 3 T demonstrated substantial increase of 1/T 0 2 in the SN of PD patients but not 1/T 2 , 16 as predicted. In subsequent studies, the results were confirmed and also extended to the basal ganglia, 17,18 clearly indicating that 1/T 0 2 yields stronger correlations with brain iron in PD than 1/T 2 . In principle, iron content could also be investigated using 1/T Ã 2 (those signal changes caused by the sum of 1/T 0 2 and 1/ T 2 ).…”

Comparing real‐world advantages for the clinical neuroradiologist between a high field (3 T), a phased array (1.5 T) vs. a single‐channel 1.5‐T MR system

“…3-T clinical systems are now commercially available and 7-T and 8-T human research systems are in use (6,7). Early reports demonstrate the utility of modern high field systems in detecting different types of brain lesions (8 -10) and in demonstrating underlying anatomy with high spatial resolution (11,12). Early measurements on high field systems have shown increased SNR and CNR and also increased artifact conspicuity (12).…”