Ultra Low Field Magnetic Resonance Imaging and Computed Tomography in the Diagnosis of Lumbar Disc Disease

Magnetic resonance (MR) examination of the lumbar spine was performed in 51 patients using a resistive magnet with a field strength of 0.02 T. The results at 105 intervertebral levels were compared with those of computed tomography (CT). Due to the extremely low field strength, an unfavourable signal-to-noise ratio degraded the image quality. Some improvement was achieved with the development of a dedicated surface coil. The diagnostic information was not comparable with that obtained with CT, nor was the image quality comparable to that obtained at higher field strengths. Compared with CT there was no false information. Therefore, it is suggested that extremely low field units may permit exclusion of pathology on the basis of a normal examination and in this way help in the selection of those patients who need further investigation and treatment.