title: De novo aneurysm formation and growth of untreated aneurysms: a 5-year MRA follow-up in a large cohort of patients with coiled aneurysms and review of the literature.
abstract: OBJECTIVE
  Rates of development of de novo intracranial aneurysms and of growth of untreated additional aneurysms are largely unknown. We performed MRA in a large patient cohort with coiled aneurysms at 5-year follow-up.
  
  
  METHODS
  In 276 patients with coiled intracranial aneurysms and 5±0.5 years of follow-up MRA (totaling 1332 follow-up patient-years), additional aneurysms were classified as unchanged, grown, de novo, or incomparable with previous imaging. We calculated 5-year cumulative incidence of de novo aneurysm formation and growth of untreated aneurysms. We searched PubMed and EMBASE databases for studies assessing aneurysm development, and growth.
  
  
  RESULTS
  In 50 of 276 patients (18%), 75 additional aneurysms were present at follow-up MRA. Of these 75, 2 were de novo (both 3 mm), 58 were unchanged, 5 had grown from 1 to 3 mm (7.9% of 63 known additional aneurysms; 95% CI, 1.3%-14.6%), and 10 were incomparable. Five-year cumulative incidence for a de novo aneurysm developing was 0.75%. Four additional aneurysms in 3 patients were treated. Ten previous studies reported annual incidences of growth of additional aneurysms ranging from 1.51% to 22.7%, and 5 studies reported annual incidences of de novo aneurysm formation ranging from 0.3 to 1.8%.
  
  
  CONCLUSIONS
  MRA screening of patients with coiled aneurysms within the first 5 years after treatment has a low rate of de novo aneurysm development and growth of additional aneurysms, and an even lower treatment rate.
authors.affiliation: Department of Radiology, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands. S.P.Ferns@amc.uva.nl
authors.forename: Sandra P
authors.initials: SP
authors.lastname: Ferns
authors.forename: Marieke E S
authors.initials: ME
authors.lastname: Sprengers
authors.forename: Willem Jan J
authors.initials: WJ
authors.lastname: van Rooij
authors.forename: René
authors.initials: R
authors.lastname: van den Berg
authors.forename: Birgitta K
authors.initials: BK
authors.lastname: Velthuis
authors.forename: Gérard A P
authors.initials: GA
authors.lastname: de Kort
authors.forename: Menno
authors.initials: M
authors.lastname: Sluzewski
authors.forename: Wim H
authors.initials: WH
authors.lastname: van Zwam
authors.forename: Gabriël J E
authors.initials: GJ
authors.lastname: Rinkel
authors.forename: Charles B L M
authors.initials: CB
authors.lastname: Majoie
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000209:etiology* / Q000628:therapy; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D016896:Treatment Outcome; D055815:Young Adult