Transnasal and transsphenoidal MRI-guided biopsies of petroclival tumors

Abstract

Magnetic resonance imaging (MRI) allows excellent tissue characterization in the area of the petroclival region and can depict lesions not visualized with ultrasound or computed tomography (CT). The aim of this study was to demonstrate the clinical feasibility and utility of an interactive MR‐guidance system to target and biopsy tumors in the petroclival region. MRI‐guided biopsies of 10 patients with tumors in the clivus and petrous apex were performed in an open 0.5‐T MR system. Lesions were targeted through a transsphenoidal or transnasal approach. Imaging during biopsies was achieved by a combination of standard and interactive mode. T1‐weighted spin‐echo, T2‐weighted fast spin‐echo (FSE), and three‐dimensional T1‐weighted gradient‐echo (GRE) scans (standard mode) were selected to provide optimal tissue characterization for both the lesion and surrounding structures and varied according to the anatomic site. For interactive imaging, T1‐weighted GRE and T2‐weighted FSE sequences were used. We performed MRI‐guided transsphenoidal biopsies in 10 patients who had lesions identified by CT (n = 5) and/or MRI (n = 10). The indications for biopsies were to differentiate between suspected malignant processes (n = 4 ) and benign processes (n = 6). Lesions adjacent to structures like the internal carotid artery were accurately targeted in particular. All biopsies were performed successfully and were the basis for selection of further treatment. No complications occurred during the procedures. An open MR system allows interactive control of biopsies in the area of the petroclival region, providing maximum patient safety and diagnostic accuracy not possible in other systems. The advantages of MRI tissue characterization are combined with an interactive, one‐step method of localization and targeting, as well as tissue sampling. J. Magn. Reson. Imaging 2001;13:3–11. © 2001 Wiley‐Liss, Inc.

Expanded endonasal approach: fully endoscopic, completely transnasal approach to the middle third of the clivus, petrous bone, middle cranial fossa, and infratemporal fossa

“…Access to the medial petrous apex with conventional approaches can be achieved via an extended middle cranial fossa approach or via transmastoid ones. 3,14,18,27,[33][34][35][36] This can involve traction on the temporal lobe or having to dissect along the course of the facial nerve. Transnasal routes to the medial petrous apex have been reported 13,25,28 and are gaining popularity with the advent of endoscopic approaches.…”

Navigation concepts for MR image‐guided interventions

“…For the open 0.5T scanner, the hand‐eye coordination is further limited by a 7‐second display delay. The clinical experience with such a navigation technique is reported for many neurosurgical (26–30) as well as body applications (26, 31–35).…”

“…Details on corresponding imaging sequences that allow the tracking of surgical tools in near real time and an immediate control of diagnostic and therapeutic measures are given in the section Pulse Sequences and Related MRI Techniques. Besides brain interventions (27, 71–73), the system has also been used to guide various percutaneous biopsies and monitor therapy in other areas of the body, for instance, in the skull base, breast, and liver (9, 26, 35, 74).…”

Interventional and intraoperative MR: review and update of techniques and clinical experience

“…Compared to CT, by analogous spatial resolution, the MR capability to perform oblique imaging allows a greater visualization of the needle tract in relation to the lesion. This is a decisive advantage, especially in regions of complex anatomy, with many vital structures to be spared, such as in the head and neck [38] or skull base [39]. In our experience, the use of MR imaging should be recommended for guidance in the area of the clivus or petrous apex, via a transsphenoidal approach.…”