Observational Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Radiol. Oct 28, 2018; 10(10): 124-134
Published online Oct 28, 2018. doi: 10.4329/wjr.v10.i10.124
Reproducibility of thrombus volume quantification in multicenter computed tomography pulmonary angiography studies
Audrey E Kaufman, Alison N Pruzan, Ching Hsu, Sarayu Ramachandran, Adam Jacobi, Indravadan Patel, Lee Schwocho, Michele F Mercuri, Zahi A Fayad, Venkatesh Mani
Audrey E Kaufman, Alison N Pruzan, Sarayu Ramachandran, Adam Jacobi, Indravadan Patel, Lee Schwocho, Michele F Mercuri, Zahi A Fayad, Venkatesh Mani, Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
Audrey E Kaufman, Alison N Pruzan, Sarayu Ramachandran, Zahi A Fayad, Venkatesh Mani, Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, Hess Center for Science and Medicine, New York, NY 10029, United States
Ching Hsu, Indravadan Patel, Lee Schwocho, Michele F Mercuri, Daiichi Sankyo Inc., Basking Ridge, NJ 07920, United States
Author contributions: All authors designed the experiment; Kaufman AE, Pruzan AN, Ramachandran S, Mani V performed the experiment; Kaufman AE and Pruzan AN performed the image analysis; Hsu C, Pruzan AN and Mani V performed statistical analysis; Kaufman AE and Mani V wrote the draft of the manuscript; all authors critically reviewed the manuscript.
Institutional review board statement: This study was submitted to the Institutional Review Board (IRB) of the Icahn School of Medicine at Mount Sinai but was deemed that no IRB approval was necessary for conduct of this study [See Determination regarding engagement in human research letter from the program for protection of research subjects (PPHS) office IRB].
Informed consent statement: Waiver of informed consent was obtained from the Institutional Review Board as only deidentified data was used in this study. The images analyzed for this study were anonymized and devoid of any Protected Health Information.
Conflict-of-interest statement: Ching Hsu, Indravadan Patel, Lee Schwocho, Michele F Mercuri are employees of Daiichi Sankyo Inc. All other authors have no conflicts to disclose.
Data sharing statement: Once published and after appropriate safeguard to ensure that the data is devoid of any identifiers, the data used for the analysis for this study will be shared on the Mount Sinai data sharing portal according to Institutional guidelines.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Venkatesh Mani, PhD, Associate Professor, Department of Radiology, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY 10029, United States. venkatesh.mani@mountsinai.org
Telephone: +1-212-8248454 Fax: +1-646-5379589
Received: June 1, 2018
Peer-review started: June 1, 2018
First decision: July 23, 2018
Revised: July 27, 2018
Accepted: August 4, 2018
Article in press: August 4, 2018
Published online: October 28, 2018
Abstract
AIM

To evaluate reproducibility of pulmonary embolism (PE) clot volume quantification using computed tomography pulmonary angiogram (CTPA) in a multicenter setting.

METHODS

This study was performed using anonymized data in conformance with HIPAA and IRB Regulations (March 2015-November 2016). Anonymized CTPA data was acquired from 23 scanners from 18 imaging centers using each site’s standard PE protocol. Two independent analysts measured PE volumes using a semi-automated region-growing algorithm on an FDA-approved image analysis platform. Total thrombus volume (TTV) was calculated per patient as the primary endpoint. Secondary endpoints were individual thrombus volume (ITV), Qanadli score and modified Qanadli score per patient. Inter- and intra-observer reproducibility were assessed using intra-class correlation coefficient (ICC) and Bland-Altman analysis.

RESULTS

Analyst 1 found 72 emboli in the 23 patients with a mean number of emboli of 3.13 per patient with a range of 0-11 emboli per patient. The clot volumes ranged from 0.0041 - 47.34 cm3 (mean +/- SD, 5.93 +/- 10.15cm3). On the second read, analyst 1 found the same number and distribution of emboli with a range of volumes for read 2 from 0.0041 – 45.52 cm3 (mean +/- SD, 5.42 +/- 9.53cm3). Analyst 2 found 73 emboli in the 23 patients with a mean number of emboli of 3.17 per patient with a range of 0-11 emboli per patient. The clot volumes ranged from 0.00459-46.29 cm3 (mean +/- SD, 5.91 +/- 10.06 cm3). Inter- and intra-observer variability measurements indicated excellent reproducibility of the semi-automated method for quantifying PE volume burden. ICC for all endpoints was greater than 0.95 for inter- and intra-observer analysis. Bland-Altman analysis indicated no significant biases.

CONCLUSION

Semi-automated region growing algorithm for quantifying PE is reproducible using data from multiple scanners and is a suitable method for image analysis in multicenter clinical trials.

Keywords: Pulmonary embolism, Arteries, Computed tomography angiography, Computer-assisted image analysis, Thrombolytic therapy

Core tip: Blood clots that occur in deep leg veins can break away and cause the serious complication of clots (then termed emboli) lodged in the lungs. Measuring the volume of the emboli with a semi-automated region growing software program using computed tomography pulmonary angiogram data can be helpful to evaluate treatment efficacy in clinical drug trials. This study demonstrates the technique to be reproducible both between image analysts and when repeated by the same image analyst when the data is obtained in a multicenter setting.