Abnormal spinal cord morphology Spinal cord H sign 2025-12-17T15:52:15Z The H sign can be ascertained by spinal magnetic resonance imaging (MRI) and represents spinal cord myelitis isolated to the gray matter. A longitudinally extensive T2 hyperintense spinal cord lesion from C6 to T10, predominantly involving the gray matter. The appearance of the anomaly is said to resemble the letter H. H sign in the spinal cord The H sign can be observed with Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), multiple sclerosis, and other neuroimmunological diseases.