title: Use of follow-up imaging in isolated perimesencephalic subarachnoid hemorrhage: a meta-analysis.
abstract: OBJECTIVE
  Multiple studies have shown that negative computed tomographic angiograms (CTAs) are reliable in excluding aneurysms in patients with isolated perimesencephalic subarachnoid hemorrhage (pSAH). We evaluate the use of digital subtraction angiography versus CTA for initial diagnosis and of angiographic follow-ups in patients with pSAH by performing an institutional analysis and a meta-analysis of literature.
  
  
  METHODS
  Retrospective institutional analysis of patients with pSAH was performed from 2008 to 2014. The number and types of follow-up imaging studies were tabulated. Initial and follow-up studies were evaluated by an experienced neuroradiologist for intracranial aneurysm. Meta-analysis of literature was performed to assess the use of initial digital subtraction angiography and of follow-up imaging.
  
  
  RESULTS
  Our institutional review revealed no additional use of initial digital subtraction angiography or of any angiographic follow-up after initial negative CTA in patients with pSAH on noncontrast CT. Meta-analysis of 40 studies yielded a total of 1031 patients. Only 8 aneurysms were first diagnosed on follow-ups (0.78%). Careful review showed that some of these aneurysms reported on follow-up are of questionable validity. Initial digital subtraction angiography and follow-up imaging after a negative initial CTA showed no statistically significant benefits.
  
  
  CONCLUSIONS
  In patients meeting the strict imaging criteria of pSAH, initial negative CTA is reliable in excluding aneurysms. A critical review of the literature through meta-analysis shows no foundation for multiple follow-up studies in patients with pSAH.
authors.affiliation: From the Departments of Diagnostic Radiology (V.B.K., X.W., C.C.M., A.M.) and Neurosurgery (C.C.M.), Yale School of Medicine, New Haven, CT.
authors.forename: Vivek B
authors.initials: VB
authors.lastname: Kalra
authors.affiliation: From the Departments of Diagnostic Radiology (V.B.K., X.W., C.C.M., A.M.) and Neurosurgery (C.C.M.), Yale School of Medicine, New Haven, CT.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wu
authors.affiliation: From the Departments of Diagnostic Radiology (V.B.K., X.W., C.C.M., A.M.) and Neurosurgery (C.C.M.), Yale School of Medicine, New Haven, CT.
authors.forename: Charles C
authors.initials: CC
authors.lastname: Matouk
authors.affiliation: From the Departments of Diagnostic Radiology (V.B.K., X.W., C.C.M., A.M.) and Neurosurgery (C.C.M.), Yale School of Medicine, New Haven, CT. ajay.malhotra@yale.edu.
authors.forename: Ajay
authors.initials: A
authors.lastname: Malhotra
mesh_terms: D003952:Diagnostic Imaging / Q000706:statistics & numerical data* / Q000639:trends; D005500:Follow-Up Studies; D006801:Humans; D008636:Mesencephalon / Q000473:pathology*; D012189:Retrospective Studies; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis* / Q000453:epidemiology
keywords: angiography, digital subtraction; meta-analysis