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Molecular Image Directed 3D Ultrasound Guided Biopsy

Author: Baowei Fei, PhD

Systematic transrectal ultrasound (TRUS)-guided prostate biopsy is considered as the standard method for prostate cancer detection. The current biopsy technique has a significant sampling error and can miss at least 20% of cancers. As a result, a patient may be informed of a negative biopsy result but may in fact be harboring an occult early-stage cancer. It is a difficult challenge for physicians to manage patients with false negative biopsies who, in fact, harbor curable prostate cancer as indicated by biochemical measurements such as rising prostate specific antigen (PSA), as well as patients diagnosed with early-stage disease.

Although ultrasound imaging is a preferred method for image-guided biopsy because it is performed in real time and because it is portable and cost effective, current ultrasound imaging technology has difficulty to differentiate carcinoma from benign prostate tissue. Various PET imaging agents have been developed for prostate cancer detection and staging. MR spectroscopic imaging (MRSI) is playing an increasing role in prostate cancer management. Combined PET and/or MRI/MRSI allow metabolic and structural evaluation of prostate cancer and improve the diagnostic accuracy for localizing and detecting the disease.

Figure 1

The 3D pelvic structure and the prostate (green) are segmented from CT images. The tumor (red) is obtained from the registered PET image. The ultrasound image is registered with the PET/CT and is displayed within the pelvis. By combining PET/CT and TRUS, the fusion visualization will guide the biopsy needle to the suspicious tumor target (Image in color).

At our NIH/NCI-supported Emory Molecular and Translational Imaging Center, positron emission tomography (PET) with a new molecular imaging tracer FACBC has shown very promising results for prostate cancer detection in human patients.

We hypothesize that FACBC PET molecular images can be incorporated into ultrasound-guided biopsy for improved cancer detection. The proposed research is to develop a molecular image-directed, 3D ultrasound-guided system for targeted biopsy of the prostate.

  • Specific Aim 1: To modify a real-time, mechanically assisted, 3D ultrasound-guided device. Compared to conventional 2D image guidance, 3D images of the prostate will be used to guide the biopsy.
  • Specific Aim 2: To develop fast deformable and statistical appearance model based segmentation methods for 3D ultrasound images of the prostate. Statistical shape models will be developed from our database and will be used to guide automatic segmentation of the prostate.
  • Specific Aim 3: To combine FACBC molecular images with 3D ultrasound for targeted biopsy. New deformable image registration methods based joint saliency map and fuzzy point correspondence will be developed in order to solve major limitations of mutual information based image registration.
  • Specific Aim 4: To test the accuracy of the integrated biopsy system in phantoms and animals. The complete biopsy system will also be tested in a small number of human patients. If completely developed, the multimodality molecular image-guided system will be able to be used not only for biopsy but also for brachytherapy, radiofrequency thermal ablation, cryotherapy, and photodynamic therapy. The research could improve prostate cancer detection by using novel molecular imaging technology and by using a new three-dimensional image-guided biopsy device. The molecular image-guided system can be used not only for improved biopsy of diseases but also for minimally invasive therapy of cancers.

Project Team

Baowei Fei, PhD, EngD (PI);  David Schuster, MD, Weiping Yu, PhD, Aaron Fenster, PhD, Viraj Mater, MD, Peter Nieh, MD