Verification of needle guidance accuracy in pelvic phantom using registered ultrasound and MRI images for intracavitary/interstitial gynecologic brachytherapy

Abstract

Purpose: In combined intracavitary/interstitial (IC/IS) gynecologic brachytherapy, trackers attached to interstitial needles of localize real-time needle trajectories, and intraoperative ultrasound (US) images provide updated anatomy information during needle insertions. To achieve an effective visualization and image guidance, real-time needle trajectories and US images can be unified in preoperative magnetic resonance imaging (MRI) image space together. This study evaluates the rigid registration accuracy between US images and MRI images as well as the registration accuracy between US images and real-time needle trajectories in a pelvic phantom. Material and methods: A method for US probe calibration and accomplished rigid registration between MRI images and US images was proposed. An IC/IS applicator was designed. Micro electromagnetic sensor to track and localize real-time needle trajectories in 3D MRI image space was used. Marker validation to test the accuracy of US probe calibration and pelvic phantom validation to test the registration accuracy between US images and MRI images was conducted as well as and pelvic phantom study to verify the registration accuracy between real-time needle trajectories and needle trajectories in registered US images. Results: US probe calibration accuracy was 0.80 ±0.23 mm (n = 60). Registration accuracy between US images and MRI images were 1.01 ±0.22 mm in the axial plane (n = 60) and 1.14 ±0.20 mm in the sagittal plane (n = 24). Registration accuracy between real-time needle trajectories and needle trajectories in registered US images were 1.25 ±0.31 mm (n = 40) and 1.61 ±0.28 degrees (n = 5), respectively. Conclusions: In this study, we showed that under ideal conditions, rigid registration between MRI images and US images obtained high accuracy for real-time image guidance. Additionally, registered US images provided accurate image guidance during visual needle insertion in IC/IS gynecologic brachytherapy to achieve a combination of effective visualization and image guidance.

Verification of Guiding Needle Placement by Registered Ultrasound Image During Combined Intracavitary/Interstitial Gynecologic Brachytherapy

“…Our research group tested the feasibility of guiding needle placement by registered US images in gynecologic interstitial brachytherapy. While the use of preoperative MRI images had been reported 16 in our previous study, this experiment demonstrated that under ideal conditions, rigid registration between CT images and US images obtained high accuracy for real-time image guidance.…”

“…In our CT-based brachytherapy, the mean target registration error (TRE) in the phantom was similar to the MRI-based brachytherapy (0.935 ± 0.166 mm vs. 1.01 ±0.22 mm in the axial plane and 0.916 ± 0.143 mm vs. 1.14 ± 0.20 mm in the sagittal plane). In the MRI-based brachytherapy, 16 the mean angle difference ± SD between US images and interstitial needle’s real-time space model was 1.61 ± 0.28 degrees for five needles in the phantom. We will analyze the entire needle trajectory as future work for CT-based brachytherapy.…”

“…An agar lump had the same composition as the uterus phantom to support it. 16 , 17 The whole phantom was kept in a container with plastic particles marked on the container’s inner wall.

Figure 4 The phantom.

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“…Registered US images performed an accurate combination of effective visualization and image guidance during visual needle insertion in gynecologic brachytherapy. 16 To gain further insight into the involvement of preoperative images, the work presented in this paper focused on applying the previously established procedures to a new context, including preoperative CT images.…”

Research on Intraoperative Organ Motion Tracking Method Based on Fusion of Inertial and Electromagnetic Navigation

“…Therefore, to address the problem of insufficient stability of a single sensor, Max Q.-H. Meng et al proposed a method to solve the problem of intraoperative occlusion as well as limited field of view of optical tracking systems by fusing multiple monocular optical sensors in an array [24], and Zhang Y. D. et al proposed a method based on the fusion of intraoperative ultrasound images with electromagnetic localization to achieve movement tracking of intraoperative local lesion locations [25]. Jiang-Sun et al oriented to the problem of image navigation during surgery improved the intraoperative navigation rate and alignment accuracy by ultrasound and magnetic resonance image fusion method [26]. All of the above researches have made a lot of useful explorations in intraoperative navigation.…”