Accuracy of true frameless stereotaxy: in vivo measurement and laboratory phantom studies

Abstract

The authors present the results of accuracy measurements, obtained in both laboratory phantom studies and an in vivo assessment, for a technique of frameless stereotaxy. An instrument holder was developed to facilitate stereotactic guidance and enable introduction of frameless methods to traditional frame-based procedures. The accuracy of frameless stereotaxy was assessed for images acquired using 0.5-tesla or 1.5-tesla magnetic resonance (MR) imaging or 2-mm axial, 3-mm axial, or 3-mm helical computerized tomography (CT) scanning. A clinical series is reported in which biopsy samples were obtained using a frameless stereotactic procedure, and the accuracy of these procedures was assessed using postoperative MR images and image fusion. The overall mean error of phantom frameless stereotaxy was found to be 1.3 mm (standard deviation [SD] 0.6 mm). The mean error for CT-directed frameless stereotaxy was 1.1 mm (SD 0.5 mm) and that for MR image-directed procedures was 1.4 mm (SD 0.7 mm). The CT-guided frameless stereotaxy was significantly more accurate than MR image-directed stereotaxy (p = 0.0001). In addition, 2-mm axial CT-guided stereotaxy was significantly more accurate than 3-mm axial CT-guided stereotaxy (p = 0.025). In the clinical series of 21 frameless stereotactically obtained biopsies, all specimens yielded the appropriate diagnosis and no complications ensued. Early postoperative MR images were obtained in 16 of these cases and displacement of the biopsy site from the intraoperative target was determined by fusion of pre- and postoperative image data sets. The mean in vivo linear error of frameless stereotactic biopsy sampling was 2.3 mm (SD 1.9 mm). The mean in vivo Euclidean error was 4.8 mm (SD 2 mm). The implications of these accuracy measurements and of error in stereotaxy are discussed.

Frame-based stereotaxy in a frameless era: current capabilities, relative role, and the positive- and negative predictive values of blood through the needle

“…Dorward et al [27] found a euclidean error of 4.8 mm in the in vivo arm of their study. Mascott et al [26] report mean localization errors between 3.3 and 5.4 mm.…”

“…Studies using phantom models typically measure the mean error of localization, which represents the average magnitude of the distance between the probe and its intended target. This should not be confused with the mean errors reported for individual axes in some in vivo [27] and phantom [28] studies which utilized planar imaging to measure targeting accuracy. In such instances mean errors refers to the average error within a single anatomic plane.…”

Frameless Stereotactic Surgery Using Intraoperative High-Field Magnetic Resonance Imaging

“…The accuracy of the present method is comparable to those of both frame-based and frameless stereotaxy methods. 2,3,22) Review of the largest published series of 7471 stereotactic brain biopsies found the average diagnostic yield was 91% (80-99%), the mortality was 0.7% (0.5-2.6%), and the morbidity was 3.5% (0-13%). 8) In our series, none of the biopsy samples yielded normal brain tissue, and a final histological diagnosis was obtained in all cases.…”

“…The frameless stereotaxy technique can eliminate the cumbersome head frames, including the time for application, and achieved an accuracy comparable to frame-based stereotaxy. 1,3,4,14,22) Intraoperative magnetic resonance (iMR) imaging and MR-compatible devices have been developed for stereotactic procedures. Two different approaches to the clinical application of iMR imaging have been reported: low-field iMR imaging for stereotactic procedures because of the easy access to patients due to the open configuration, 2,16,25,26) and high-field MR imaging.…”

Neuronavigation accuracy dependence on CT and MR imaging parameters: a phantom-based study

“…Finally, the chosen experimental approach allows us to separately evaluate the imaging contribution and the global accuracy, while in the literature, with few exceptions (Kaus et al 1997, Torresin et al 1999, only the latter one is normally investigated (Dorward et al 1999, Vannier and Haller 1999, Zylka et al 1999, Maciunas et al 1994, Willems et al 2001. …”