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Background: This work evaluated the accuracy and safety of a protocol for minimally-invasive flapless zygomatic implant placement that uses computer-guided stereolithographic mucosa-supported surgical templates., Methods: A total of six zygomatic implants were placed in three formalin-fixed human cadaver heads, with edentulous and severely atrophic posterior maxillae. CT scans of each cadaver head were performed after zygomatic implant placement, to evaluate the lateral error (LE) at implant tip and base, and the angular error (AE) of the implant body., Results: Excluding the implant placed outside the drilling channel, the LE at the implant base was less than 1 mm in all cases. The average LE at the tip was 3.86 mm, and the AE was less than 6° in all cases, with an average of 4.5°., Conclusion: Computer-guided minimally-invasive flapless zygomatic implant surgery remains challenging. Careful planning and perfect stability of the surgical guide are essential., (Copyright © 2015 John Wiley & Sons, Ltd.)

Background: Accurate needle placement is crucial for the success of percutaneous radiological needle interventions. We compared three guiding methods using an optical-based navigation system: freehand, using a stereotactic aiming device and active depth control, and using a stereotactic aiming device and passive depth control., Methods: For each method, 25 punctures were performed on a non-rigid phantom. Five 1 mm metal screws were used as targets. Time requirements were recorded, and target positioning errors (TPE) were measured on control scans as the distance between needle tip and target., Results: Time requirements were reduced using the aiming device and passive depth control. The Euclidian TPE was similar for each method (4.6 ± 1.2-4.9 ± 1.7 mm). However, the lateral component was significantly lower when an aiming device was used (2.3 ± 1.3-2.8 ± 1.6 mm with an aiming device vs 4.2 ± 2.0 mm without)., Discussion: Using an aiming device may increase the lateral accuracy of navigated needle insertion., (Copyright © 2013 John Wiley & Sons, Ltd.)

Background: The aim of this study was to evaluate the CT-guided stereotactic targeting accuracy for radiofrequency ablation of osteoid osteoma (OO), a small, benign but painful osseous lesion., Methods: Patient and extremity were fixed in a vacuum cushion. The OO was targeted using an optical navigation system with a stereotactic targeting device. For evaluation of targeting errors, the control CT with the needle in place was fused with the planning CT., Results: In 16 consecutive patients, nine OOs in the femur, four in the tibia, one in the spine, one in the ulna and one in the pubic bone were successfully targeted without complications. The mean ± SD lateral targeting error was 2.6 ± 1.7 mm at the needle entry and 1.9 ± 1.2 mm at the needle tip, and the mean angular error was 2.0 ± 1.3°., Conclusion: Stereotaxy allows for accurate and safe targeting of OOs in various bone regions., (Copyright © 2012 John Wiley & Sons, Ltd.)

Background: Brain biopsies (BB) and depth electrode placements (DEP) are increasingly performed using frameless stereotactic targeting devices. This paper is intended to provide a comprehensive review of the technical features, targeting errors and clinical results., Methods: A PubMed literature search from 1995-2010 was performed., Results: (A) Modified stereotactic arcs, (B) arm-based devices with and without aiming facilities, and (C) skull affixed devices were found. Guidance technologies were navigation systems (all groups), prospective stereotaxy and custom designed platforms (group C). Mean total errors ranged between 4.4 and 5.4 mm for BB and 2.0 and 3.2 mm for DEP. Diagnostic yield of BB was 89-100%. The clinical success rate for DEP was 96-100%., Conclusions: Frameless stereotactic targeting devices may reach targeting errors and clinical results comparable with standard frame-based stereotaxy. Advantages and disadvantages of different devices should be acknowledged to ensure optimal technical performance., (Copyright © 2011 John Wiley & Sons, Ltd.)

Background: Control of respiratory motion is an essential prerequisite for stereotactic computer-assisted and robotic interventions in the liver., Methods: The respiratory motion control error (RMCE) of temporary disconnections of the endotracheal tube (ETT) in anaesthetized patients has been evaluated during computer tomography (CT)-guided liver punctures. Two arterial and portal phase contrast-enhanced planning CTs were obtained during one ETT disconnection. After liver puncture, a native control CT was performed during a second ETT disconnection. By image fusion, the Euclidean errors of corresponding external and internal targets were calculated as baseline measures. RMCE was obtained by subtracting the Euclidean error during one ETT disconnection from the Euclidean error during two ETT disconnections., Results: In 26 patients, the overall mean RMCE showed 1.98 +/- 0.93 (range 0.44-4.02) mm for external targets and 1.41 +/- 0.75 (range 0.46-3.18) mm for the internal targets, without significant difference in means (p = 0.558). No complications were noted., Conclusions: Temporary ETT disconnections are safe and may control respiratory motion for liver interventions within 4 mm., (Copyright 2010 John Wiley & Sons, Ltd.)

Background: Assessment of errors is essential in development, testing and clinical application of computer-assisted neurosurgery. Our aim was to provide a comprehensive overview of the different methods to assess target registration error (TRE) and target positioning error (TPE) and to develop a proposal for a standardized reporting of error assessment., Methods: A PubMed research on phantom, cadaver or clinical studies on TRE and TPE has been performed. Reporting standards have been defined according to (a) study design and evaluation methods and (b) specifications of the navigation technology., Results: The proposed standardized reporting includes (a) study design (controlled, non-controlled), study type (non-anthropomorphic phantom, anthropomorphic phantom, cadaver, patient), target design, error type and subtypes, space of TPE measurement, statistics, and (b) image modality, scan parameters, tracking technology, registration procedure and targeting technique., Conclusions: Adoption of the proposed standardized reporting may help in the understanding and comparability of different accuracy reports., (Copyright (c) 2009 John Wiley & Sons, Ltd.)

Background: Navigated oral implant surgery requires knowledge and skills in computed tomography (CT) imaging, three-dimensional (3D) planning, and use of surgical navigation systems. To improve teaching and training, a laboratory training and evaluation technique has been developed., Methods: The technique uses a surgical navigation system, a dental dummy and anonymous data of previously treated patients, including duplicated dental stone casts, individualized registration mouthpieces and CT scans. Training consists of definition of the prosthetic goal, 3D planning and navigated model surgery. For evaluation, a post-surgical CT of the drilled dental stone casts is fused with the original planning CT., Results: Each step of navigated implant surgery can be simulated and trained. Post-surgical evaluation includes Euclidean distance, normal distance, angular deviations and damage to critical anatomical structures, such as nerves and sinuses., Conclusions: The presented technique allows for successful laboratory training and evaluation of computer-aided oral implant surgery.