Three-dimensional sonography with needle tracking: role in diagnosis and treatment of prostate cancer

Abstract

Objective: Image-guided prostate biopsy has become routine in medical diagnosis. Although it improves biopsy outcome, it mostly operates in 2 dimensions, therefore lacking presentation of information in the complete 3-dimensional (3D) space. Because prostatic carcinomas are nonuniformly distributed within the prostate gland, it is crucial to accurately guide the needles toward clinically important locations within the 3D volume for both diagnosis and treatment.

Methods: We reviewed the uses of 3D image-guided needle procedures in prostate cancer diagnosis and cancer therapy as well as their advantages, work flow, and future directions.

Results: Guided procedures for the prostate rely on accurate 3D target identification and needle navigation. This 3D approach has potential for better disease diagnosis and therapy. Additionally, when fusing together different imaging modalities and cancer probability maps obtained from a population of interest, physicians can potentially place biopsy needles and other interventional devices more accurately and efficiently by better targeting regions that are likely to host cancerous tissue.

Conclusions: With the information from anatomic, metabolic, functional, biochemical, and biomechanical statuses of different regions of the entire gland, prostate cancers will be better diagnosed and treated with improved work flow.

Figure 1

Comparison between 2D and 3D displays of biopsy procedures. A, Screen capture of sonograms of a prostate phantom. Only 2 views, transverse (top) and sagittal (bottom), are visible. B and C, Screen captures from the Eigen Artemis system showing a subsequent biopsy procedure. B, Unregistered previous (green) and current (pink) volumes. C, Registered volumes with previous (white) and current (green) core locations inside.

Figure 2

A, Eigen electromechanical tracker. It has 4° of freedom with a fulcrum for TRUS-guided biopsy. B, With the end-firing ultrasound probe, there is wide needle coverage of the prostate by rotation of the transducer probe (as indicated by the broad curved arrow at the bottom) with the anus as a fulcrum. The dashed probe outline shows the TRUS probe at the left extreme position. The biopsy needle is straight so that the range of motion that it spans makes a cone shape with an angle of 160°.

Figure 3

Three-dimensional reconstruction of prostate models. A, Digitized image of a single slice of a step-sectioned radical prostatectomy specimen. B, Stacked surgical margin contour controls of original slices. C, Surgical margin contour interpolation. D, Three-dimensional reconstructed prostate model.

Figure 4

Cancer probability map overlaid onto 3D sonograms. A and B, Two different views of the same prostate atlas. Colors represent the probability of cancer.

Figure 5

Simulated tracking targets in repeated biopsy. A, Screen capture from the Eigen software showing sextant biopsies (white, old; and green, new) in an oblique view. B, Bottom view.