MRI-TRUS Multi-modality Image Fusion For Targeted Prostate Biopsy

Prostate cancer is the most frequently noncutaneous cancer in male population and the second leading cause of cancer death among them in Europe. The incidence of prostate cancer in China also showed a rising trend in recent years. Currently, transrectal ultrasound(TRUS) guided systematic biopsy is the gold standard investigation for diagnosing prostate cancer due to its real-time and radiation-free imaging capability, low cost and operation simplicity, however, its lack of image resolution and incapability to clearly visualize early-stage prostate cancer result in false-negative rates up to 30%, which would have brought great pains to the patient by raising the possibility of a repeat biopsy. Magnetic resonance multi parameter imaging(MRI) is considered to be the most effective method for the diagnosis of prostate cancer because of its high specificity and sensitivity to the diagnosis of prostate cancer. However, considering its high price, time-consuming and complex operation, MRI is not suitable as a guided imaging mode in the operation. This paper is going to proposed a new targeted prostate biopsy system based on multi modal image fusion of MRI-TRUS, which will help to improve the biopsy accuracy and the positive rate of prostate cancer.In our research, a high precision electromagnetic locator is used to build a real-time and stabled prostate biopsy system by tracking the ultrasound probe and punctured needle, which will fuse previously acquired MRI image to real-time TRUS image to provide more quality guidance. Specific steps are as follows: Initially, synchronized the image and its position information before using 3N-wire calibrated phantom and its improved model to realize 2D and 3D probe calibration; Secondly, manual rigid registration is explored for the 3D TRUS and MRI images; Thirdly, pre-interventional 3D ultrasound image is registered with real-time ultrasound image automatically through 2D and 3D probe calibration. After that, the prostate targeting biopsy guidance is realized by combining the result of needle calibration and the fused output of real-time ultrasound images and MRI images. To validate the efficacy of our developed system, the experiments were carried out on two commercial prostate phantoms. All 12 biopsies can hit the randomly placed 0.5 cm3 lesion within the phantom. And the procedural targeting error between planned and documented biopsy is 2.89 mm at average. The result demonstrates that both the precision and operating complexity of our system are largely improved compared with traditional method, which means this system is expected in the clinical application.