Developing a knowledge base to support the annotation of ultrasound images of ectopic pregnancy

Abstract

Background: Ectopic pregnancy is a frequent early complication of pregnancy associated with significant rates of morbidly and mortality. The positive diagnosis of this condition is established through transvaginal ultrasound scanning. The timing of diagnosis depends on the operator expertise in identifying the signs of ectopic pregnancy, which varies dramatically among medical staff with heterogeneous training. Developing decision support systems in this context is expected to improve the identification of these signs and subsequently improve the quality of care. In this article, we present a new knowledge base for ectopic pregnancy, and we demonstrate its use on the annotation of clinical images.

Results: The knowledge base is supported by an application ontology, which provides the taxonomy, the vocabulary and definitions for 24 types and 81 signs of ectopic pregnancy, 484 anatomical structures and 32 technical elements for image acquisition. The knowledge base provides a sign-centric model of the domain, with the relations of signs to ectopic pregnancy types, anatomical structures and the technical elements. The evaluation of the ontology and knowledge base demonstrated a positive feedback from a panel of 17 medical users. Leveraging these semantic resources, we developed an application for the annotation of ultrasound images. Using this application, 6 operators achieved a precision of 0.83 for the identification of signs in 208 ultrasound images corresponding to 35 clinical cases of ectopic pregnancy.

Conclusions: We developed a new ectopic pregnancy knowledge base for the annotation of ultrasound images. The use of this knowledge base for the annotation of ultrasound images of ectopic pregnancy showed promising results from the perspective of clinical decision support system development. Other gynecological disorders and fetal anomalies may benefit from our approach.

Keywords: Application ontology; Ectopic pregnancy; Knowledge base.

Fig. 1

Graphical view of the "ectopic pregnancy" concept from the Radiology Lexicon (RadLex, version 3.13.1), with a full expansion of the concepts neighborhood for "ectopic pregnancy"[RadLex:RID4942]

Fig. 2

Overview of the design of the knowledge system for ectopic pregnancy: ontology design, reference image collection and application for image annotation

Fig. 3

Simplified representation of the sign "ring of fire" in the knowledge base

Fig. 4

Taxonomy of ectopic pregnancy by implantation sites (view of the Ectopic Pregnancy Ontology)

Fig. 5

Overview of the interface of the web application for ectopic pregnancy ultrasound image annotations. This graphical user interface was developed using the AngularJS (https://github.com/angular/angular.js) and Bootstrap (https://github.com/twbs/bootstrap)

Fig. 6

Precision of ectopic pregnancy sign annotations in ultrasound images