Rim and Flame Signs: Postgadolinium MRI Findings Specific for Non-CNS Intramedullary Spinal Cord Metastases

Abstract

BACKGROUND AND PURPOSE:No highly specific MR imaging features distinguishing ISCMs from primary cord masses have been described. Our purpose was to retrospectively compare peripheral enhancement features on postgadolinium MR imaging of ISCMs with primary intramedullary cord masses.

Intramedullary Spinal Cord Metastases: Visibility on PET and Correlation with MRI Features

“…lesion location, maximal superior-inferior enhancement length (size [mm] and extent [number of vertebral body segments]), extent of T2 signal abnormality (number of vertebral segments), ratio of extent of T2 signal abnormality to contrast enhancement, and presence/absence of "rim" and "flame" signs, 13 2 postgadolinium MR imaging findings specific for ISCM.…”

“…Several MR imaging lesion characteristics previously analyzed by 2 radiologists (F.E.D. and J.B.R., a neuroradiology fellow with an American Board of Radiology certification) 13,14 were noted:…”

“…13 For inclusion in the current study, this group was refined to those patients in whom a PET scan (either PET/CT or PET only) was also available for electronic review. It was assumed that the number of potential cases of ISCM seen on PET at our institution but not imaged with MR imaging (and thus not included in our 45-patient cohort) would be negligible or nonexistent, given that patients would be expected to undergo spinal MR imaging if an ISCM was first suggested at PET.…”

Intramedullary Spinal Cord Metastases: MRI and Relevant Clinical Features from a 13-Year Institutional Case Series

“…These 58 patients with ISCM also were the basis for a recent study, which described 2 specific enhancement features on postgadolinium MR imaging in ISCMs compared with primary cord masses. 7 Five (9%) of these 58 patients were excluded for the current (and the prior) study because of the lack of available pretreatment MR imaging examination. Note that included in the current study but excluded in the prior study were 4 patients who lacked available postgadolinium pretreatment MR imaging.…”

“…Thus, eccentric/exophytic lesions were further characterized as either clearly intramedullary or possibly of leptomeningeal origin with spinal cord invasion, on the basis of which was dominant, the intramedullary or the cord surface component. In addition, for the exophytic lesions: 1) original MR imaging reports were reviewed to assess whether the interpreting radiologist described an intramedullary mass with exophytic extension or a leptomeningeal mass with invasion, and 2) previous categorization of "rim" and "flame" signs, 7 two postgadolinium MR imaging findings specific for ISCM, was noted. Note also that leptomeningeal lesions without an apparent intramedullary component were not considered to be ISCMs.…”