Operator guidance in 2D echocardiography via 3D model to image registration

ABSTRACT Ubiquitous use of 2D ultrasound (US) is limited by the diculty in interpretation of images for an untrainedoperator. We present a solution for operator guidance through visual cues via registration of US to a 3D model.The method is demonstrated on 2D echocardiography data, where we are able to localize the scan plane inrelation to the standard planes on the 3D model. Our algorithm operates by pre-processing both the US andCT images to the most basic information- muscle, blood pool - using classi“cation. Subsequently, these labelsare registered using the match cardinality metric for binary labeled images. We evaluated our method on fourparasternal long-axis and three parasternal short-axis images from dierent patients. Results show that oursystem is able to correctly distinguish between the dierent US standard views and is able to localize the scanon the 3D model, correctly on “ve out of seven cases.Keywords: Ultrasound, Image Registration, 2D Echocardiography 1. INTRODUCTION As a radiationless, real-time, and low-cost technique, ultrasound (US) is a common imaging modality with manyapplications both in medical diagnosis and therapy. 2D US systems have the highest penetration amongst anyimaging device. Recent trends in manufacturing and miniat urization are increasing distribution, so much so,that they are being used by general pra ctitioners. However, ubiquitous u se of the 2D US device is hampered bythe diculty in interpr etation of US images.Traditionally, this diculty has been surmounted through exhaustive training and “eld practice. Duringthese sessions, the sonographers learn the critical factors for obtaining a good ultrasound image such as theselection of the scanning window on the patient and the localization of the scanning plane.We investigate the feasibility of an image based approach to impart this information. In our approach, thenovice operator is interactively guided to acquire a good scan plane by visual cues on a 3D model of the anatomyof interest. In addition to providing road-map assistance, another advantage of this technology is that it mayresult in standardization while taking 2D views for measurement purposes. This is valuable in 2D US as the”exibility of the device causes high variability of measurement planes.Our approach is to use image registration to indicate, in a 3D model, how far/close the user is to a standardscan-plane. The feasibility of this technique is demonstrated in 2D echocardiography, where we apply 2D-3D registration to guide the user to the standard planes (see Fig. 1). The method makes anatomy speci“cassumptions, but we perceive easy extension to other anatomy using an appropriate 3D model with extractedstandard planes.In the past few years, there has been extensive work in the registration of US to other modalities (prominentlyCT and MR). Penney et al.