Dr. Nishanth Khanna Profile

Dr. Nishanth Khanna

at Johns Hopkins Univ

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Publications (2)

SPIE Journal Paper | 13 May 2020

Automatic analysis of global spinal alignment from simple annotation of vertebral bodies

Sophia Doerr, Tharindu De Silva, Rohan Vijayan, Runze Han, Ali Uneri, Michael Ketcha, Xiaoxuan Zhang, Nishanth Khanna, Erick Westbroek, Bowen Jiang, Corinna Zygourakis, Nafi Aygun, Nicholas Theodore, Jeffrey Siewerdsen

JMI, Vol. 7, Issue 03, 035001, (May 2020) https://doi.org/10.1117/12.10.1117/1.JMI.7.3.035001

KEYWORDS: Image segmentation, Computed tomography, Spine, Radiography, Surgery, 3D image processing, Image analysis, Visualization, Reliability, Image-guided intervention

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Proceedings Article | 8 March 2019 Presentation + Paper

Automatic analysis of global spinal alignment from spine CT images

S. Doerr, T. De Silva, R. Vijayan, R. Han, A. Uneri, M. Ketcha, X. Zhang, N. Khanna, E. Westbroek, B. Jiang, C. Zygourakis, N. Aygun, N. Theodore, J. Siewerdsen

Proceedings Volume 10951, 1095104 (2019) https://doi.org/10.1117/12.2513975

KEYWORDS: Image segmentation, Computed tomography, Spine, Error analysis, Surgery, Image processing algorithms and systems, Clouds, Principal component analysis, 3D image processing, Radiography

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Purpose: A method for automatic computation of global spinal alignment (GSA) metrics is presented to mitigate the high variability of manual definitions in radiographic images. The proposed algorithm segments vertebral endplates in CT as a basis for automatic computation of metrics of global spinal morphology. The method is developed as a potential tool for intraoperative guidance in deformity correction surgery, and/or automatic definition of GSA in large datasets for analysis of surgical outcome. Methods: The proposed approach segments vertebral endplates in spine CT images using vertebral labels as input. The segmentation algorithm extracts vertebral boundaries using a continuous max-flow algorithm and segments the vertebral endplate surface by region-growing. The point cloud of the segmented endplate is forward-projected as a digitally reconstructed radiograph (DRR), and a linear fit is computed to extract the endplate angle in the radiographic plane. Two GSA metrics (lumbar lordosis and thoracic kyphosis) were calculated using these automatically measured endplate angles. Experiments were performed in seven patient CT images acquired from Spineweb and accuracy was quantified by comparing automatically-computed endplate angles and GSA metrics to manual definitions. Results: Endplate angles were automatically computed with median accuracy = 2.7°, upper quartile (UQ) = 4.8°, and lower quartile (LQ) = 1.0° with respect to manual ground-truth definitions. This was within the measured intra- observer variability = 3.1° (RMS) of manual definitions. GSA metrics had median accuracy = 1.1° (UQ = 3.1°) for lumbar lordosis and median accuracy = 0.4° (UQ = 3.0°) for thoracic kyphosis. The performance of GSA measurements was also within the variability of the manual approach. Conclusions: The method offers a potential alternative to time-consuming, manual definition of endplate angles for GSA computation. Such automatic methods could provide a means of intraoperative decision support in correction of spinal deformity and facilitate data-intensive analysis in identifying metrics correlating with surgical outcomes.

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