title: Changes of size and shape of small, unruptured intracranial aneurysms in repeated computed tomography angiography studies.
abstract: BACKGROUND
  Unruptured intracranial aneurysms (UIAs) are frequently detected in noninvasive imaging studies such as computed tomography angiography (CTA) or magnetic resonance angiography (MRA). If small, UIAs are observed in these modalities in order to detect growth or shape change, but there are many questions about proper protocol of the follow-up.
  
  
  OBJECTIVE
  To assess changes of small (< 7 mm) UIAs dome size and shape in repeated CTA studies as predictors of growth and rupture.
  
  
  METHODS
  One hundred and ten UIAs (10 posterior circulation) in 70 patients (55 women) were observed, with a cumulative observation time of 333.32 years. Aneurysms' dome and neck perpendicular dimensions were measured in the first and the last CTA study at least twice with the developed application. Confidence intervals (CI) for measurements and dome shape parameters were calculated. For aneurysms ruptured during follow-up intermediate studies were analyzed. Patients' clinical information was recorded. The aneurysm growth detection algorithm integrated CI and spatial resolution of the CT scanner.
  
  
  RESULTS
  Twenty-three aneurysms increased in volume, 10 in height and 14 in dome width. Volume increased in 90% of cases of height and 93% of width increase. Posterior circulation aneurysms grew faster than anterior ones (p < 0.003), but calculated time to significant size increase (eT) did not differ between the groups due to higher CI in the posterior circulation. Analysis of eT with Kaplan-Meier curves showed that 75% of growing aneurysms could be detected in the first 3 years of observation. During the follow-up 3 aneurysms bled, and they grew faster than other growing aneurysms. Two of the bleeding aneurysms formed daughter sacs.
  
  
  CONCLUSIONS
  Dome volume assessment is superior to single dimension assessment in aneurysm growth detection. Confidence intervals assessment helps to avoid overestimation of growth. Seventy-five percent of growing aneurysms could be detected in the first 3 years of observation. Daughter sac formation and fast increase in size are strong predictors of aneurysm rupture.
authors.affiliation: Second Department of Radiology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Jarosław
authors.initials: J
authors.lastname: Żyłkowski
authors.affiliation: Chair and Department of Neurosurgery, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Przemysław
authors.initials: P
authors.lastname: Kunert
authors.affiliation: Second Department of Radiology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Jaworski
authors.affiliation: Second Department of Radiology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Rosiak
authors.affiliation: Chair and Department of Neurosurgery, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Marchel
authors.affiliation: Second Department of Radiology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Olgierd
authors.initials: O
authors.lastname: Rowiński
keywords: computed tomography angiography; dome shape; dome size; unruptured intracranial aneurysm