Augmenting intraoperative ultrasound with preoperative magnetic resonance planning models for percutaneous renal access

Abstract

BackgroundUltrasound (US) is a commonly-used intraoperative imaging modality for guiding percutaneous renal access (PRA). However, the anatomy identification and target localization abilities of the US imaging are limited. This paper evaluates the feasibility and efficiency of a proposed image-guided PRA by augmenting the intraoperative US with preoperative magnetic resonance (MR) planning models.MethodsFirst, a preoperative surgical planning approach is presented to define an optimal needle trajectory using MR volume data. Then, a MR to US registration is proposed to transfer the preoperative planning into the intraoperative context. The proposed registration makes use of orthogonal US slices to avoid local minima while reduce processing time. During the registration, a respiratory gating method is used to minimize the impact of kidney deformation. By augmenting the intraoperative US with preoperative MR models and a virtual needle, a visual guidance is provided to guarantee the correct execution of the surgical planning. The accuracy, robustness and processing time of the proposed registration were evaluated by four urologists on human data from four volunteers. Furthermore, the PRA experiments were performed by the same four urologists on a kidney phantom. The puncture accuracy in terms of the needle-target distance was measured, while the perceptual quality in using the proposed image guidance was evaluated according to custom scoring method.ResultsThe mean registration accuracy in terms of the root mean square (RMS) target registration error (TRE) is 3.53 mm. The RMS distance from the registered feature points to their average is 0.81 mm. The mean operating time of the registration is 6'4". In the phantom evaluation, the mean needle-target distance is 2.08 mm for the left lesion and 1.85 mm for the right one. The mean duration for all phantom PRA tests was 4'26". According to the custom scoring method, the mean scores of the Intervention Improvement, Workflow Impact, and Clinical Relevance were 4.0, 3.3 and 3.9 respectively.ConclusionsThe presented image guidance is feasible and promising for PRA procedure. With careful setup it can be efficient for overcoming the limitation of current US-guided PRA.

Kidney Targeting and Puncturing During Percutaneous Nephrolithotomy: Recent Advances and Future Perspectives

“…To reduce X-ray use in PCNL, techniques based on ultrasonography (US), magnetic resonance (MR), and endoscopic imaging have been successfully reported in several studies. 10,13,15 The use of US is being recognized as a safe and effective method of conducting surgical needles in percutaneous procedures, because it enables real-time image acquisition, is versatile, and has a reduced cost when compared with other imaging options. 27 As a result of the absence of ionizing radiation, this is often the method of choice in pregnant patients and those with transplanted organs.…”

“…Several authors have explored the combination of different imaging techniques. Among these, Li and associates 15 have explored a rigid registry process, using the Interactive Closest Points algorithm, applied to intraoperative US images and preoperative MR images, through the manual selection of pairs of points in both images from the cranial pole, caudal pole, and kidney hilum. A respiratory gating method was also used to minimize the impact of kidney deformation, where the US images were only obtained at the same stages of the respiration cycles-with a mean squared error of 3.53 mm.…”

“…15,22 Although without current application to PCNL, B-Splines have been explored as a nonrigid method, due to its simplicity and robustness, with a particular potential for alignment of lower anatomic structures. 31 Endoscopic imaging.…”

“…Human error may stem from the misinterpretation of images during puncture, and fluoroscopic methods do not yet allow the distinction between different tissue layers. 13,15,24 Although real-time images may facilitate the puncture step by providing a visualization of the target and surgical instruments, the use of CT and fluoroscopy are limited by the exposition of ionizing radiation and its associated risks. 34 Mancini and colleagues 35 reported higher body mass index, greater stone burden, nonbranched stones, and multiple nephrostomy access tracts as the main aspects for increased radiation exposure during PCNL.…”

“…In what concerns PCNL puncture in particular, the most relevant contributions have been provided by the application of medical imaging techniques, as well as the fusion of multiple imaging procedures. 10,13,15,16 Aside from medical imaging, robotic systems, 13,17,18 navigation systems, 19 finite element models, 20,21 and recent developments in computer graphics and image processing 13 have been proposed in recent years to improve percutaneous puncture. However, the use of new solutions not dependent on medical imaging, in current surgical practice, is still very limited.…”