The aspect ratio (dome/neck) of ruptured and unruptured aneurysms

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Object. In this retrospective study the authors examined the aspect ratio (AR; the maximum dimension of the dome/width of the neck of an aneurysm) and compared the distribution of this ratio in a group of ruptured and unruptured aneurysms. A similar comparison was performed in relation to the maximum dimension of the aneurysm alone. The authors sought to evaluate the utility of these measures for differentiating ruptured and unruptured aneurysms.

Methods. Measurements were made of 774 aneurysms in 532 patients at three medical centers. One hundred twenty-seven patients harbored only unruptured lesions, 290 only ruptured lesions, and 115 both ruptured and unruptured lesions. Cases were included if angiograms were available for measurement and the status of the individual patient's aneurysm(s) was known.

The odds of a lesion falling in the ruptured aneurysm group increased with both the lesion's maximum size and the AR. The odds ratio for rupture rose progressively only for the AR. The distribution curves showed that ruptured aneurysms were larger and had greater ARs. The mean size of unruptured aneurysms was 7 mm and that of ruptured ones was 8 mm; the corresponding mean ARs were 1.8 and 3.4, respectively. The odds of rupture were 20-fold greater when the AR was larger than 3.47 compared with an AR less than or equal to 1.38. Only 7% of ruptured aneurysms had an AR less than 1.38 compared with 45% of unruptured lesions.

Conclusions. The AR is probably a useful index to calculate. A high AR might reasonably influence the decision to treat actively an unruptured aneurysm independent of its maximum size. Prospective studies are warranted.

Article Information

Address reprint requests to: Bryce Weir, M.D., 230 Westridge Road, Edmonton, Alberta, T5T 1C1, Canada. email: bkaweir@telus.net.

© AANS, except where prohibited by US copyright law.

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Figures

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    Drawings of representative ARs (1.2, 1.6, and 3.6). An AR of 3.6 is much more likely to be associated with a ruptured aneurysm than an AR of 1.2, even if both have the same maximum size.

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    Kernel density plots. Upper: Plot for maximum linear dimension of the aneurysm (size [1]), excluding patients with aneurysms larger than 25 mm. The numbers on the y axis represent the relative frequencies per millimeter of aneurysm size. The area under each curve is equal to 1. Lower: Plot for the AR in the same group of patients. The numbers on the y axis represent the relative frequencies per unit of AR.

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    Graphs demonstrating ORs associated with ruptured aneurysms. Upper: Adjusted for patient sex and the location of the aneurysm, the risk of rupture increases with the size of the lesion. Compared with aneurysms 4 mm or smaller, the ORs for the three larger categories of size were 2.95, 3.66, and 3.67 (p < 0.001 for all), but the differences among the three larger groups were small. Lower: Compared with aneurysms that have an AR 1.38 or less, the ORs for the three groups of lesions with higher ARs were 4.66, 10.7, and 20.4 (p < 0.001).

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    Graph depicting the ROC curves for aneurysm size (the maximum dimension of the lesion) and AR. For the AR the arrow denotes the point on the curve corresponding to a cutpoint of 1.6. Circles designate aneurysm sizes and triangles ARs. The ROC area for aneurysm size is 0.6195; the ROC area for the AR is 0.7854.

References

  • 1.

    Debrun GMAletich VAKehrli Pet al: Selection of cerebral aneuryms for treatment using Guglielmi detachable coils: the preliminary University of Illinois at Chicago experience. Neurosurgery 43:128112971998Debrun GM Aletich VA Kehrli P et al: Selection of cerebral aneuryms for treatment using Guglielmi detachable coils: the preliminary University of Illinois at Chicago experience. Neurosurgery 43:1281–1297 1998

    • Search Google Scholar
    • Export Citation
  • 2.

    DeLong ERDeLong DMClarke-Pearson DL: Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach. Biometrics 44:8378451988DeLong ER DeLong DM Clarke-Pearson DL: Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach. Biometrics 44:837–845 1988

    • Search Google Scholar
    • Export Citation
  • 3.

    Dickey PSKailasnath P: Comment on Ujiie H, Tamano Y, Sasaki K, et al: Is the aspect ratio a reliable index for predicting the rupture of a saccular aneurysm? Neurosurgery 48:4955032001Dickey PS Kailasnath P: Comment on Ujiie H Tamano Y Sasaki K et al: Is the aspect ratio a reliable index for predicting the rupture of a saccular aneurysm? Neurosurgery 48:495–503 2001

    • Search Google Scholar
    • Export Citation
  • 4.

    Hosmer DW JrLemeshow S: Applied Logistic Regression. New York: John Wiley & Sons1989Hosmer DW Jr Lemeshow S: Applied Logistic Regression. New York: John Wiley & Sons 1989

    • Search Google Scholar
    • Export Citation
  • 5.

    Metz CE: Basic principles of ROC analysis. Semin Nucl Med 8:2832981978Metz CE: Basic principles of ROC analysis. Semin Nucl Med 8:283–298 1978

    • Search Google Scholar
    • Export Citation
  • 6.

    Ujiie HTamano YSasaki KHori T: Is the aspect ratio a reliable index for predicting the rupture of a saccular aneurysm? Neurosurgery 48:4955032001Ujiie H Tamano Y Sasaki K Hori T: Is the aspect ratio a reliable index for predicting the rupture of a saccular aneurysm? Neurosurgery 48:495–503 2001

    • Search Google Scholar
    • Export Citation

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