PERADS.net: Automated PE-RADS Grading with Named Anatomic Localization and Right-to-Left Ventricular Ratio Measurement on CT Pulmonary Angiography
- 1Humanitas University, Department of Biomedical Sciences, Pieve Emanuele, Milan, Italy
Abstract
PurposeTo develop an automated pipeline (PERADS.net) that segments acute pulmonary embolism on CT pulmonary angiography, assigns a Pulmonary Embolism Reporting and Data System (PE-RADS) grade with named anatomic localization, and measures the right-to-left ventricular (RV/LV) diameter ratio, and to assess radiologist agreement.
Materials and MethodsIn this retrospective study, 120 CT pulmonary angiograms (70 peripheral, 35 central, 15 negative) from the public RSNA Pulmonary Embolism CT dataset were analyzed. A two-channel five-fold nnU-Net ensemble segmented the embolus; the pulmonary arterial tree was reduced to a branching graph, and the grade was set by the most proximal level with at least 1% of embolic volume.
Three radiologists, blinded to the algorithm-assigned grade, independently assigned grades and rated RV/LV plausibility. Agreement was assessed with percent agreement and Cohen or Fleiss kappa on five-grade and grouped scales (grade 0 versus 1-2 versus 3-4). The automated ratio was compared with the datasets binary RV/LV label in 2119 examinations.
ResultsAgreement between the algorithm and three-radiologist consensus (n = 119) was 60.5% (kappa, 0.38) for individual grades and 90.8% (kappa, 0.74; 95% CI: 0.59, 0.87) for the grouped scale; 34 of 47 discordant examinations fell within grades 3-4. As a fourth reader, the algorithm matched grouped-scale interobserver agreement (mean kappa, 0.62 versus 0.67). Radiologists showed no agreement rating RV/LV plausibility as favorable or incorrect (Fleiss kappa, -0.00), whereas the automated ratio agreed with the external label (kappa, 0.49), overestimating strain 3.1:1.
ConclusionAutomated PE-RADS grading agreed with radiologist consensus comparably to a fourth reader on the grouped scale.
Summary StatementAn automated pipeline assigned PE-RADS grades agreeing with three-radiologist consensus at a level approaching interobserver agreement on the clinically grouped scale, while automated RV/LV measurement showed no reader agreement on plausibility.
Key PointsO_LIIn 120 CT pulmonary angiograms, agreement between automated and consensus PE-RADS grading was 90.8% (kappa, 0.74; 95% CI: 0.59, 0.87) on the clinically grouped scale (grade 0 versus 1-2 versus 3-4) and 60.5% (kappa, 0.38; 95% CI: 0.24, 0.51) on the five-grade scale. C_LIO_LITreated as a fourth reader, the algorithm reached grouped-scale agreement with individual radiologists (mean kappa, 0.62) comparable to that observed among radiologists themselves (mean kappa, 0.67). C_LIO_LIAutomated right-to-left ventricular ratio agreed moderately with an independent binary label in 2119 examinations (kappa, 0.49; 95% CI: 0.45, 0.52), whereas three radiologists showed no agreement when rating the same measurement as favorable or incorrect (Fleiss kappa, -0.00; 95% CI: -0.09, 0.09). C_LI
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BibTeX
@misc{lanza2026peradsnet,
title = {{PERADS.net: Automated PE-RADS Grading with Named Anatomic Localization and Right-to-Left Ventricular Ratio Measurement on CT Pulmonary Angiography}},
author = {E. Lanza and F. Catapano and C. Lisi and F. D'Orazio and R. Levi and A. Laghi},
howpublished = {medRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.15.26363142},
url = {https://www.medrxiv.org/content/10.64898/2026.09.15.26363142v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - PERADS.net: Automated PE-RADS Grading with Named Anatomic Localization and Right-to-Left Ventricular Ratio Measurement on CT Pulmonary Angiography
AU - E. Lanza
AU - F. Catapano
AU - C. Lisi
AU - F. D'Orazio
AU - R. Levi
AU - A. Laghi
PY - 2026
DA - 2026/09/15
PB - medRxiv
DO - 10.64898/2026.09.15.26363142
UR - https://www.medrxiv.org/content/10.64898/2026.09.15.26363142v1
AB - PurposeTo develop an automated pipeline (PERADS.net) that segments acute pulmonary embolism on CT pulmonary angiography, assigns a Pulmonary Embolism Reporting and Data System (PE-RADS) grade with named anatomic localization, and measures the right-to-left ventricular (RV/LV) diameter ratio, and to assess radiologist agreement. Materials and MethodsIn this retrospective study, 120 CT pulmonary angiograms (70 peripheral, 35 central, 15 negative) from the public RSNA Pulmonary Embolism CT dataset were analyzed. A two-channel five-fold nnU-Net ensemble segmented the embolus; the pulmonary arterial tree was reduced to a branching graph, and the grade was set by the most proximal level with at least 1% of embolic volume. Three radiologists, blinded to the algorithm-assigned grade, independently assigned grades and rated RV/LV plausibility. Agreement was assessed with percent agreement and Cohen or Fleiss kappa on five-grade and grouped scales (grade 0 versus 1-2 versus 3-4). The automated ratio was compared with the datasets binary RV/LV label in 2119 examinations. ResultsAgreement between the algorithm and three-radiologist consensus (n = 119) was 60.5% (kappa, 0.38) for individual grades and 90.8% (kappa, 0.74; 95% CI: 0.59, 0.87) for the grouped scale; 34 of 47 discordant examinations fell within grades 3-4. As a fourth reader, the algorithm matched grouped-scale interobserver agreement (mean kappa, 0.62 versus 0.67). Radiologists showed no agreement rating RV/LV plausibility as favorable or incorrect (Fleiss kappa, -0.00), whereas the automated ratio agreed with the external label (kappa, 0.49), overestimating strain 3.1:1. ConclusionAutomated PE-RADS grading agreed with radiologist consensus comparably to a fourth reader on the grouped scale. Summary StatementAn automated pipeline assigned PE-RADS grades agreeing with three-radiologist consensus at a level approaching interobserver agreement on the clinically grouped scale, while automated RV/LV measurement showed no reader agreement on plausibility. Key PointsO_LIIn 120 CT pulmonary angiograms, agreement between automated and consensus PE-RADS grading was 90.8% (kappa, 0.74; 95% CI: 0.59, 0.87) on the clinically grouped scale (grade 0 versus 1-2 versus 3-4) and 60.5% (kappa, 0.38; 95% CI: 0.24, 0.51) on the five-grade scale. C_LIO_LITreated as a fourth reader, the algorithm reached grouped-scale agreement with individual radiologists (mean kappa, 0.62) comparable to that observed among radiologists themselves (mean kappa, 0.67). C_LIO_LIAutomated right-to-left ventricular ratio agreed moderately with an independent binary label in 2119 examinations (kappa, 0.49; 95% CI: 0.45, 0.52), whereas three radiologists showed no agreement when rating the same measurement as favorable or incorrect (Fleiss kappa, -0.00; 95% CI: -0.09, 0.09). C_LI
ER -