title: MR imaging of giant intracranial aneurysm.
abstract: We reviewed the clinical features and findings of magnetic resonance imaging (MRI) in 17 cases of giant intracranial aneurysm (GIA). All were confirmed by digital subtraction angiography (DSA). Seven were non-thrombosed and 10 were partially thrombosed.All thrombosed parts showed no enhancement. The majority of the lumen showed good enhancement in the post-contrast study (89%). About 80% of the partially thrombosed aneurysms had an onion skin appearance on non-contrast T1WI. On T2WI about 80% of partially thrombosed aneurysms had a low signal inside the thrombus or its wall from the susceptibility effect of blood elements such as haemosiderin. Flow void sign was noted in 88% on non-contrast T1WI and T2WI. Flow artifacts along the phase-encoding direction from the lumen of the aneurysm were noted in 41% of non-contrast T1WI, 56% of contrast-enhanced T1WI, and 29% of T2WI.Non-enhancement inside the thrombus and an onion skin appearance were important signs of thrombosis of the aneurysm. Flow artifacts along the phase-encoding direction from the lumen of the aneurysm provided an important clue of a patent lumen inside an aneurysm. The following signs provided clues to the diagnosis of patency lumen instead of thrombosis with high sensitivity and specificity: flow void sign on noncontrast T1WI (sensitivity 88%, specificity 100%), enhancement on contrast-enhanced T1WI (sensitivity 89%, specificity 100%), presence of either flow void sign or enhancement on contrast-enhanced T1WI (sensitivity 100%, specificity 100%).
authors.affiliation: Department of Radiology, Taipei Veterans General Hospital, Peitou, Taiwan. mhteng@vghtpe.gov.tw
authors.forename: Michael Mu-Huo
authors.initials: MM
authors.lastname: Teng
authors.forename: S M
authors.initials: SM
authors.lastname: Nasir Qadri
authors.forename: Chao-Bao
authors.initials: CB
authors.lastname: Luo
authors.forename: Jiing-Feng
authors.initials: JF
authors.lastname: Lirng
authors.forename: Shin-Su
authors.initials: SS
authors.lastname: Chen
authors.forename: Cheng-Yen
authors.initials: CY
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D000792:Angiography / Q000379:methods; D016477:Artifacts; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012867:Skin / Q000473:pathology