Assessing the volume of large cerebral arteriovenous malformations: Can the ABC/2 formula reliably predict true volume?

Alon Kashanian; Hiro Sparks; Tania Kaprealian; Nader Pouratian

doi:10.1016/j.jocn.2019.04.038

Assessing the volume of large cerebral arteriovenous malformations: Can the ABC/2 formula reliably predict true volume?

J Clin Neurosci. 2019 Jul:65:1-5. doi: 10.1016/j.jocn.2019.04.038. Epub 2019 May 4.

Authors

Alon Kashanian¹, Hiro Sparks¹, Tania Kaprealian², Nader Pouratian³

Affiliations

¹ Department of Neurosurgery, David Geffen School of Medicine at UCLA (University of California, Los Angeles), 300 UCLA Stein Plaza, Suite 420, Los Angeles, CA, USA.
² Department of Radiation Oncology, David Geffen School of Medicine at UCLA (University of California, Los Angeles), 200 UCLA Medical Plaza, Suite B265, Los Angeles, CA, USA.
³ Department of Neurosurgery, David Geffen School of Medicine at UCLA (University of California, Los Angeles), 300 UCLA Stein Plaza, Suite 420, Los Angeles, CA, USA; Department of Radiation Oncology, David Geffen School of Medicine at UCLA (University of California, Los Angeles), 200 UCLA Medical Plaza, Suite B265, Los Angeles, CA, USA. Electronic address: NPouratian@mednet.ucla.edu.

PMID: 31064679
DOI: 10.1016/j.jocn.2019.04.038

Abstract

Background: Outcomes of stereotactic radiosurgery in the treatment of cerebral arteriovenous malformations (AVMs) are volume-dependent. The ability to estimate AVM volume has significant value in guiding AVM management.

Objective: To determine whether AVM volume measurement calculated from the ABC/2 formula is accurate compared to volume calculated by a computer-assisted planimetric method for large AVMs.

Methods: Retrospective review of 42 intracranial AVMs >3 cm in diameter that underwent treatment with dose-staged hypofractionated stereotactic radiotherapy (HSRT) from 2001 to 2018. Two raters independently measured pre- and post-HSRT volumes using both the ABC/2 formula and computer-assisted planimetry in a blinded fashion. Inter-rater reliability was assessed by calculation of intra-class correlation coefficient (ICC). Absolute volumes and percent volume change following HSRT as determined using the two methods were compared using paired t-tests, linear regression, and Bland-Altman plot analyses.

Results: The ICC between the 2 raters for planimetric and ABC/2 volumes was 0.859 and 0.799, respectively. ABC/2 volumes, 26.1 ± 26.6 cm³, were statistically smaller than planimetric volumes, 28.6 ± 27.1 cm³ (P = .008). Despite differences, the two methods were highly correlated (R² = 0.904, linear regression). The percent volume change following HSRT was significantly greater with the ABC/2 method than compared to planimetry (P = .009).

Conclusion: The ABC/2 and planimetric methods are reproducible for measuring cerebral AVM volumes. Although the ABC/2 method of volume estimation underestimates planimetric AVM volume, the high correlation between the two suggests utility of the ABC/2 method if one understands its limits, particularly with respect to estimating change in AVM volume after treatment.

Keywords: ABC/2; Cerebral arteriovenous malformations; Planimetry; Radiosurgery; Volume.

MeSH terms

Adolescent
Adult
Female
Humans
Image Interpretation, Computer-Assisted / methods*
Imaging, Three-Dimensional / methods
Intracranial Arteriovenous Malformations / pathology*
Intracranial Arteriovenous Malformations / surgery
Magnetic Resonance Imaging
Male
Middle Aged
Neuroimaging / methods*
Radiation Dose Hypofractionation
Radiosurgery / methods
Reproducibility of Results
Retrospective Studies
Tomography, X-Ray Computed
Treatment Outcome