RT Journal Article SR Electronic T1 An Unusual Cause of “Doughnut” Sign in Brain Scanning JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 432 OP 433 VO 16 IS 5 A1 Jon M. Beauchamp A1 Martin A. Belanger A1 Harold R. Neitzschman YR 1975 UL http://jnm.snmjournals.org/content/16/5/432.abstract AB