Development of an ultrasound phantom for spinal injections with 3-dimensional printing

This report describes a method for producing anatomically detailed, low-cost ultrasound phantoms of the spine with 3-dimensional printing. An implementation that involves representing a portion of the lumbar spine and the ligamentum flavum with 2 different printing materials and the surrounding soft tissues with agar gel is presented.

A computed tomography image volume of a patient with normal spinal anatomy was segmented to isolate the spine. Segments representing the ligamentum flavum and a supporting pedestal were digitally added, and the result was printed with a 3-dimensional printer. The printed spine was embedded in agar gel as a soft tissue component. Ultrasound images of the phantom were acquired and compared with those acquired from a human patient.

The sonographic appearances of the phantom compared favorably with those observed from the human patient. The soft tissue component was suitable for needle insertions and could be remade replacing the agar.

Ultrasound phantoms that are derived directly from patient anatomy have strong potential as learning tools for ultrasound-guided spinal insertions, and they could be used as preprocedural planning tools in cases involving pathologies, implants, or abnormal anatomies. Three-dimensional printing is a promising method for producing low-cost phantoms with designs that can be readily shared across clinical institutions.