Clinical NMR Imaging of the Brain: 140 Cases

Abstract

Cranial nuclear magnetic resonance (NMR) scans were performed on 13 healthy volunteers and 140 patients with a broad spectrum of neurologic disease and compared with x-ray computed tomography (CT) scans. The NMR scans included a variety of sequences reflecting proton density, blood flow, T₁, and T₂ as well as transverse, sagittal, and coronal images. White matter, gray matter, and cerebrospinal fluid were clearly distinguished in the normal brain with inversion-recovery (IR) sequences, and normal progressive myelination was demonstrated in infants and children.

Acute hemorrhages displayed short T₁ values, but other pathologic processes such as infarction, infection, demyelination, edema, and malignancy were associated with long T₁ values. Cysts had very long T₁ values (about that of cerebrospinal fluid). Spinecho (SE) sequences showed increased values of T₂ in a variety of conditions and highlighted lesions against the relatively featureless background of the remaining brain. With inversion-recovery scans, different stages of infarction were recognized in the hemispheres. NMR was more useful than CT in demonstrating brainstem infarction.

The white matter lesions in demyelinating diseases were well demonstrated with NMR scans. Many more lesions were observed in multiple sclerosis with NMR than with CT. Benign tumors were well seen and usually had shorter T₁ values than malignant tumors. Mass effects from tumors were generally better demonstrated with NMR than with CT, including more subtle mass effects such as displacement of the external capsule. Abnormalities were seen in diseases of the basal ganglia, including marked atrophy of the head of the caudate nucleus in Huntington chorea.

Advantages of NMR imaging include the high level of gray–white matter contrast, lack of bone artifact, variety of possible sequences, transverse, sagittal, and coronal imaging, sensitivity to pathologic change, and lack of known hazard. Disadvantages include lack of bone detail, limited spatial resolution, lack of contrast agent s, and cost. Promising directions for future clinical research include developmental neurology, tissue characterization with T₁ and T₂, assessment of blood flow, and the development of contrast agents. Much more detailed evaluation will be required, but NMR seems to be a potentially important addition to existing techniques of neurologic diagnosis.