CT to US registration of the lumbar spine: A clinical feasibility study

Abstract

Spine needle injections are widely applied to alleviate pain and to remove nerve sensation through analgesia and anesthesia. Currently, spinal injections are performed using either no image guidance or modalities that expose the patient to ionizing radiation such as fluoroscopy or computed tomography (CT). Ultrasound (US) is being investigated as an alternative as it is a non-ionizing and more accessible image modality. An inherent challenge to US imaging of the spine is the acoustic shadows created by the bony structures of the vertebrae limiting visibility. It is possible to enhance the anatomical information in US through its fusion with a pre-operative CT. In this manuscript we propose a clinical feasibility study involving a novel registration pipeline to align CT and US images of the spine. This pipeline involves automatic global and multi-vertebrae registration. We evaluate the proposed methodology on five clinical data sets. The proposed method is able to register the data sets from initial misalignments of up to 25 mm, with a mean TRE of 1.17 mm, sufficient for many spine needle interventions. © 2014 Springer International Publishing Switzerland.