title: "Comet tail sign": A pitfall of post-gadolinium magnetic resonance imaging findings for metastatic brain tumors.
abstract: A highly enhanced cap attached to the surface of metastatic tumors in the brain parenchyma is occasionally encountered on magnetic resonance (MR) images. This atypical enhanced cap tends to occur in severe peritumoral edema and may produce the characteristic bulge of a metastatic mass lesion termed the "comet tail sign" (CTS). The purpose of this study was to demonstrate the features of the CTS using MR imaging and pathological findings, and to clarify its clinical relevance. We selected 21 consecutive cases of newly diagnosed metastases from MR imaging studies that demonstrated the CTS; all had diffuse peritumoral edema. The MR T2-weighted images showed similarly homogenous and high intensity signals in both the tail and peritumoral edema. Fourteen of the 21 patients underwent surgical resection of their tumors, and 12 tails were separately removed for pathological examination, no tumor cells which revealed. We speculate that the CTS does not contain neoplastic tissues but is observed as a result of the leakage of contrast medium from the tumor body into the interstitial space of the white matter. Although CTS is a peculiar and uncommon enhancement pattern, it has clinical significance in determining the extent of the margin for invasive local treatments, such as surgical resection or stereotactic radiotherapy; this is particularly true in and near the eloquent areas.
authors.affiliation: Division of Neurosurgery, Shizuoka Cancer Center, 1007 Naga-izumi, Shizuoka, 411-8777, Japan. k.mitsuya@scchr.jp.
authors.forename: Koichi
authors.initials: K
authors.lastname: Mitsuya
authors.affiliation: Division of Neurosurgery, Shizuoka Cancer Center, 1007 Naga-izumi, Shizuoka, 411-8777, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nakasu
authors.affiliation: Division of Neurosurgery, National Cancer Center, Tokyo, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Narita
authors.affiliation: Division of Neuro-oncology, Kusatsu General Hospital, Shiga, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakasu
authors.affiliation: Division of Neurosurgery, National Cancer Center, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ohno
authors.affiliation: Division of Neurosurgery, National Cancer Center, Tokyo, Japan.
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Miyakita
authors.affiliation: Division of Pathology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Abe
authors.affiliation: Division of Pathology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Ito
authors.affiliation: Division of Neurosurgery, Shizuoka Cancer Center, 1007 Naga-izumi, Shizuoka, 411-8777, Japan.
authors.forename: Nakamasa
authors.initials: N
authors.lastname: Hayashi
authors.affiliation: Division of Diagnostic Radiology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Endo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D005260:Female; D005500:Follow-Up Studies; D005682:Gadolinium; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy; D009367:Neoplasm Staging; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000628:therapy; D011379:Prognosis; D012189:Retrospective Studies
chemical_list: D005682:Gadolinium
keywords: Atypical enhancement pattern; Extravasation; Gadolinium; Magnetic resonance imaging; Metastatic brain tumor
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