title: Detection and characterization of very small cerebral aneurysms by using 2D and 3D helical CT angiography.
abstract: OBJECTIVE
  Many cases of subarachnoid hemorrhage are due to rupture of small cerebral aneurysms. Our purpose was to evaluate the usefulness of helical CT angiography (CTA) in the detection and characterization of very small (<5 mm) intracranial aneurysms.
  
  
  METHODS
  One hundred eighty consecutive patients underwent CTA for suspected intracranial aneurysms. All aneurysms prospectively detected by CTA were confirmed by digital subtraction angiography (DSA) or at surgery. CT angiograms and digital subtraction angiograms were reviewed by two independent blinded radiologists who performed aneurysm detection, quantitation, and characterization using 2D multiplanar reformatted and 3D volume-rendering techniques.
  
  
  RESULTS
  Fifty-one patients harboring 41 very small intracranial aneurysms were included in this series. Eighty-one percent (33 of 41 aneurysms) were </=4 mm in maximal diameter, and 37% (15 of 41 aneurysms) were </=3 mm in maximal diameter. Sensitivity of CTA for very small intracranial aneurysm detection ranged from 98% to 100% (95% confidence intervals, 0.871, 0.999, 0.914, and 1.0), compared with 95% for DSA. The specificity of CTA and DSA for very small intracranial aneurysms was 100% (26 of 26 aneurysms). Positive predictive value ranged from 98% to 100%. Negative predictive value ranged from 96% to 100%. Accuracy of CTA for detection of very small intracranial aneurysms was 99% and 100% (kappa = 0.969 - 1.0 +/- 0.1221). Forty-eight percent of aneurysms were detected in the presence of subarachnoid hemorrhage.
  
  
  CONCLUSIONS
  The sensitivity of CTA for the detection of cerebral aneurysms </=5 mm is higher than that of DSA, with equal specificity and high interoperator reliability. High quality, noninvasive CTA aneurysm detection and characterization can be performed using routine clinical CT scanners and commercially available image processing workstations.
authors.affiliation: Department of Radiological Sciences, University of California, Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: J Pablo
authors.initials: JP
authors.lastname: Villablanca
authors.forename: Reza
authors.initials: R
authors.lastname: Jahan
authors.forename: Parizad
authors.initials: P
authors.lastname: Hooshi
authors.forename: Silvester
authors.initials: S
authors.lastname: Lim
authors.forename: Gary
authors.initials: G
authors.lastname: Duckwiler
authors.forename: Aman
authors.initials: A
authors.lastname: Patel
authors.forename: James
authors.initials: J
authors.lastname: Sayre
authors.forename: Neil
authors.initials: N
authors.lastname: Martin
authors.forename: John
authors.initials: J
authors.lastname: Frazee
authors.forename: John
authors.initials: J
authors.lastname: Bentson
authors.forename: Fernando
authors.initials: F
authors.lastname: Viñuela
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017542:Aneurysm, Ruptured / Q000145:classification / Q000150:complications / Q000175:diagnosis; D015901:Angiography, Digital Subtraction; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D002532:Intracranial Aneurysm / Q000145:classification* / Q000150:complications / Q000175:diagnosis*; D018810:Magnetic Resonance Angiography / Q000379:methods; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013345:Subarachnoid Hemorrhage / Q000145:classification / Q000175:diagnosis / Q000209:etiology; D014057:Tomography, X-Ray Computed