Ultrasound registration: A review

•Ultrasound-to-ultrasound (monomodal) image registration is reviewed.•Elastic (non-rigid) and inelastic (rigid, affine, etc.) transforms are covered.•The literature is reviewed for the period from 1998 to 2016.•The paper is organized both by method and by anatomic application.•Concludes with a discussion of shortcomings and future opportunities.

This article is a review of registration algorithms for use between ultrasound images (monomodal image-based ultrasound registration). Ultrasound is safe, inexpensive, and real-time, providing many advantages for clinical and scientific use on both humans and animals, but ultrasound images are also notoriously noisy and subject to several unique artifacts/distortions. This paper introduces the topic and unique aspects of ultrasound-to-ultrasound image registration, providing a broad introduction and summary of the literature and the field. Both theoretical and practical aspects are introduced. The first half of the paper is theoretical, organized according to the basic components of a registration framework, namely preprocessing, image-similarity metrics, optimizers, etc. It further subdivides these methods between those suitable for elastic (non-rigid) vs. inelastic (matrix) transforms. The second half of the paper is organized by anatomy and is practical in nature, presenting and discussing the complete published systems that have been validated for registration in specific anatomic regions.