Getting the Most Out of 3 Tesla MRI of the Spine

High-field imaging of the spine with the use of 3 Tesla MRI promises improved image quality and clinical efficiency, providing excellent capability for better diagnosis and prognosis. Advanced techniques related to the spine include 3D imaging, whole-body MRI, magnetic resonance neurography, magnetic resonance spectroscopy, and functional imaging. These techniques are being used in patients with rheumatologic diseases, such as spondyloarthropathy. The main advantage of 3 Tesla MRI scans is a higher signal to noise ratio. The most widely used sequences are T1and T2-weighted sagittal, T2-weighted axial and, sometimes, T1-weighted axial. The T1 sequence is the most important for detecting bone marrow pathologies. Whole-body MRI and whole-spine MRI, both somewhat new techniques, are gaining ground in oncology for detection of metastasis. (J Musculoskel Med. 2012;29:56-C3) The use of 3 Tesla MRI scans is becoming increasingly common in clinical practice. These images offer several advantages over those obtained on the lower-field scanners, including improved image quality (higher spatial and contrast resolution) and clinical efficiency (higher temporal resolution). With the development of advanced techniques related to the spine—such as 3D imaging, whole-body MRI (WBMRI), magnetic resonance neurography (MRN), magnetic resonance spectroscopy (MRS), and functional (diffusion) imaging—high-field imaging promises excellent capability for improved diagnosis and prognosis. In this article, we review the advantages and the technical challenges related to 3 Tesla MRI of the spine to provide information on optimizing the protocol and getting the most out of 3 Tesla MRI scanners. We also review some recent advances in the techniques.FIGURE 1 Shown are coronal proton density spectral adiabatic inversion recovery fat-saturated (A) and sagittal T2-weighted turbo spin-echo (B) sequences of the lumbar spine with high resolution. Note the exit of the nerve roots (arrows). TECHNICAL CONSIDERATIONS The main advantage of 3 Tesla MRI scans can be summarized in 1 phrase: signal to noise ratio (SNR). This, the ratio between the intensity of the image’s signal and the background noise, is roughly double that of 1.5 Tesla MRI.1 Higher Spatial and Temporal Resolution A higher SNR allows for higher spatial resolution or higher temporal resolution or both (Figures 1 and 2).2 Higher spatial resolution is crucial in detecting lesions in small but important and complex anatomical structures—such as labrum pathology in the shoulder or hip and triangular fibrocartilage complex pathology in the wrist—where having a higher contrast to noise ratio also is mandatory. In the spine, high spatial and high contrast resolution play a special role in detecting nerve root, spinal cord, and neuroforaminal pathologies.3 The higher SNR also allows for higher spectral resolution; this is a substantial advantage in proton MRS and other advanced techniques. In addition,