Published online Oct 28, 2018. doi: 10.4329/wjr.v10.i10.124
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
In regard to clinical evaluation of pulmonary embolism (PE), clot burden is not a principal marker for clinical risk stratification, however clot burden is being used to assess for pharmaceutical characteristics in clinical drug trials in multicenter settings. To this point the technique has been studied with data obtained from a single imaging center using one fixed computed tomography pulmonary angiogram (CTPA) imaging protocol.
Data obtained from multicenter sites has not previously been studied. Thus, in order to validate the methods employed in multicenter clinical pharmaceutical trials of drugs such as thrombolytics, this study was commenced to assess for repeatability and consistency of clot volume measurements being obtained using semi-automated region growing techniques. Confirming the reliability of these measures has value in furthering the assessment of drug effectiveness, drug potency and in determination of optimal duration of therapy.
The key objective is to evaluate reproducibility of PE clot volume quantification using a semi-automated region growing algorithm on CTPA data in a multicenter setting.
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 was calculated per patient as the primary endpoint. Secondary endpoints were individual thrombus volume, 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. The methods employed in this study were novel in that they previously have not been used in a multicenter setting.
The results showed excellent reproducibility of inter- and intra-observer variability measurements using the semi-automated region-growing 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. The results confirm the validity of the methods used in multicenter pharmaceutical trials thereby allowing for advancement in this field.
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. The utility of validating this method could affect the advancement of thrombolytic therapy and other interventions that may be used to treat PE.
Computer-assisted image analysis has a growing role in both diagnostic and investigative imaging. This study solidifies the foundation of semi-automated region growing for volume quantification by proving the repeatability of the technique when used in a multicenter setting.