1. Intracranial AVMs: Comparison of volumes generated from orthogonal measurements and integrated 3D analysis Faiz I Syed MD MS 1, Lubomir Hadjiiski PhD 1, Aditya S Pandey MD 2, Heang-Ping Chan PhD 1, Ashok Srinivasan MD 1 Poster #: EP-62 1 Department of Radiology, University of Michigan 2 Department of Neurosurgery, University of Michigan Contact: Faiz I. Syed, syedf@med.umich.edu

2. Disclosures: None

3. Purpose Intracranial AVM volume estimation is important for – guiding therapeutic options – monitoring treated lesions Volume estimation based on orthogonal measurements is commonly used

4. Purpose The purpose of this study was to compare the intracranial AVM volumes calculated using two different methods: –calculating volume of an ellipsoid from three orthogonal measurements of the AVM –3D integrated volumetric analysis of the AVM.

5. Methods After IRB clearance, imaging studies from 11 patients with known brain AVMs were reviewed. Studies included CT of the head with contrast, CTA of the head and MRI of the head with contrast. All studies were analyzed by one board certified neuroradiologist (Reader 1) and a second year neuroradiology fellow (Reader 2) on custom software developed at the University of Michigan.

6. Methods For each patient, the AVM volume was calculated by two methods: –Ellipsoid formula ABC/2 –A, B, C: maximal orthogonal measurements of AVM nidus –3D integrated volume –calculated by tracing the boundaries of the AVM nidus on each axial slice of a cross- sectional study

7. Methods Figure1. Measuring orthogonal projections of the AVM nidus for calculating ellipsoid volume

8. Methods Figure 2. Tracing AVM nidus boundaries to calculate 3D integrated volume

9. Average volume of AVMs in our study determined by Ellipsoid and 3D Integrated volume calculations The volumes were calculated based on estimation by two readers Reader 1Reader 2 Ellipsoid volume (mL) 4.2 Range: 0.4-16.6 7.6 Range: 0.4-29.6 3D Integrated volume (mL) 6.2 Range: 0.6-23.8 6.9 Range: 0.6-21.7 Table 1. Average intracranial AVM volumes by Ellipsoid and 3D Integrated volume calculations based on estimation by two readers Results

10. Figure 3. Pearson correlation (R) for Ellipsoid volume vs 3D Integrated volume calculation for Reader 1 (R1) and Reader 2 (R2). R1 R2 R=0.99 R=0.98

11. Results Figure 4. Pearson correlation (R) for Reader 1 (R1) vs Reader 2 (R2) for the Ellipsoid and 3D Integrated volume calculations. R=0.88R=0.87

12. Conclusion There was a high inter-reader correlation for both the Ellipsoid and 3D Integrated volumes. There was a high correlation between the Ellipsoid and 3D Integrated volumes. Orthogonal volume measurement of intracranial AVMs based on the ellipsoid formula may be sufficient.

13. Limitations Our study had a small sample size of 11 patients Many of the studies analyzed had low spatial resolution

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