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Background: Precise preoperative radiological evaluation of aural atresia is of utmost importance for surgical planning. Until now, multislice computed tomography (MSCT) has been used but it cannot adequately visualize small structures such as the stapes. Flat-panel volume CT (fpVCT) with its secondary reconstructions (fpVCT SECO ) offers a high-resolution visualization of the middle ear. New otosurgical planning software also enables detailed 3D reconstruction of the middle ear anatomy., Aim of the Work: Evaluation of the use of fpVCT SECO in combination with an otosurgical planning software for a more accurate diagnosis and treatment of congenital aural atresia., Material and Methods: Seven patients with congenital aural atresia underwent preoperative MSCT (600 µm slice thickness) and corresponding fpVCT (466 µm slice thickness). In addition, fpVCT SECO (99 µm slice thickness) were reconstructed. The Jahrsdoerfer and Siegert grading scores were determined and their applicability in the abovementioned imaging modalities was evaluated. In addition, the malleus incus complex was analyzed in 3D rendering., Results: Imaging with fpVCT SECO enabled reliable visualization of the abnormalities, in particular the ossicular chain. A significant difference in the Siegert grading score was found. In addition, the malleus-incus complex could be visualized better in 3D., Discussion: The introduction of new imaging techniques and surgical planning techniques into the diagnostic concept of aural atresia facilitates the identification of malformed anatomy and enables systematic analysis. This combination can also help to more accurately classify the pathology and thus increase the safety and success of the surgical procedure., (© 2024. The Author(s).)

Background: Although knee arthroplasty represents a very successful treatment for osteoarthritis or joint destruction, a relevant number of patients is still not completely satisfied with the outcome. Higher satisfaction and faster rehabilitation seem to be achievable through patient-individualized alignment of the prosthesis and especially through reproducible robotic-assisted implantation., Importance of Robotics: The topic of robotics in orthopedics and especially in knee endoprosthesis is not new and began in the 1990s with the Robodoc system. The resurgence of robotics with new systems can be referred to as an innovation in the orthopedic operating room. Interest in this has risen significantly, not only among surgeons, but especially among patients, primarily because it seems to offer better joint function and patient satisfaction, as well as faster rehabilitation., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Graft detachment is the most common complication after Descemet membrane endothelial keratoplasty (DMEK). To assess the amount of graft detachment, precision is limited when using slit-lamp biomicroscopy. Detachment of DMEK grafts can be assessed automatically on anterior segment optical coherence tomography (AS OCT) images and allows visualization of the area and volume of detachment using 3D maps. This article provides an overview of its applications such as accurately assessing the course of natural graft attachment, identification of potential risk factors for detachment and evaluation of the long-term effect of graft detachment. The 3D map of DMEK detachment may support researchers and clinicians in precise quantification of the area and volume of graft detachment even in large data sets, and the intuitive, fast and reliable evaluation., Competing Interests: K. W. entwickelte das V-FUCHS-Instrument, das durch die Mayo Clinic an Aerie, Inc., Iris Medicine, Inc., Santen, Inc., Trefoil, Inc. und Kowa lizensiert wurde. K. W. und D. B. Z. entwickelten ein Prädiktionsinstrument zur Ödemabnahme, das durch die Uniklinik Freiburg an Oculus Optikgeräte lizensiert wurde. K. W. war Beraterin für ProQR Therapeutics. D. B. ist Berater für GSK. A. G., A. S. K., J.-L. L. und T. R. gaben an, dass keine Interessenskonflikte bestehen./K.W. developed V-FUCHS, a PROM for Fuchs endothelial dystrophy, which was licensed by the Mayo Clinic to Aerie, Inc., Iris Medicine, Inc., Santen, Inc., Trefoil, Inc. and Kowa. K.W. and D.B.Z. developed a prediction tool for edema reduction, which was licensed by the Universitätsklinikum Freiburg (Germany) to Oculus Optikgeräte GmbH. K.W. worked as consultant for ProQR Therapeutics. D.B. is consultat for GSK. The remaining authors declare that no conflict of interest exists., (Thieme. All rights reserved.)

Aim:  Archaeological objects are often recovered in blocks since highly porous materials and unstable and highly decayed objects cannot always be uncovered undamaged or time and resources for classic uncovering are lacking. Therefore, clinical computed tomography (CT) combined with freely available software solutions should be tested as a simple and fast method for visualizing and analyzing archaeological finds as an alternative to time-consuming restoration., Materials and Methods:  As an example, a block with a shield boss was selected from a block excavation and examined by means of CT. Using the freely available software 3D-Slicer (https://www.slicer.org/), the shield boss and handle were segmented in the surrounding soil with different tools. They were then digitally reconstructed and then restored using Meshmixer (Autodesk Inc., San Francisco, CA). A 3D print was generated based on the reconstructed model of the shield boss., Results:  The individual steps of CT examination of the block recovery, segmentation, reconstruction, and 3D printing were successfully performed. Based on the restored fragments of the shield boss, it was possible to date the object and to determine the initial properties of the find non-destructively without classic restoration., Conclusion:  Radiological imaging combined with digital reconstruction and 3D printing makes it possible to determine decisive characteristics of the archaeological find before it is uncovered and restored, which is a time-consuming process. This opens up new opportunities for cooperation between radiology and archaeology for the evaluation and analysis of archaeological finds., Key Points: · The transfer of medical technology, digital image processing and 3D printing to archaeology has been demonstrated.. · The digital restoration and reconstruction of archaeological objects using CT images is possible.. · Medical imaging could make a significant contribution to the investigation and reconstruction of archaeological objects.., Citation Format: · Frohwerk E, Dürr A, Fiebich M et al. Radiology meets archaeology: digital restoration and 3D printing using CT data. Fortschr Röntgenstr 2024; 196: 607 - 611., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Objectives: The aim of this study was to assess the diagnostic value of 3-dimensional dual-echo steady-state (DESS) magnetic resonance imaging (MRI) of the cervical spine at 7 T compared with 3 T in patients with cervical radiculopathy., Materials and Methods: Patients diagnosed with cervical radiculopathy were prospectively recruited between March 2020 and January 2023 before undergoing surgical decompression and received 3-dimensional DESS imaging at 3 T and 7 T MRI. Cervical nerve root compression and the dimensions of the dorsal root ganglia were assessed by 2 radiologists independently. Signal intensity, visibility of nerve anatomy, diagnostic confidence, and image artifacts were evaluated with Likert scales. The degree of neuroforaminal stenosis was assessed on standard clinical 3 T scans. Statistics included the analysis of the diagnostic accuracy and interreader reliability. The Wilcoxon signed rank test was used to assess differences between the groups., Results: Forty-eight patients (mean age, 57 ± 12 years; 22 women) were included in the study with the highest prevalence of severe neuroforaminal stenosis observed at C6 (n = 68) followed by C7 (n = 43). Direct evaluation of nerve root compression showed significantly higher diagnostic confidence and visibility of cervical nerve rootlets, roots, and dorsal root ganglia on 7 T DESS than on 3 T DESS (diagnostic confidence: P = 0.01, visibility: P < 0.01). Assessment of nerve root compression using 7 T DESS allowed more sensitive grading than standard clinical MRI ( P < 0.01) and improved the performance in predicting sensory or motor dysfunction (area under the curve combined: 0.87)., Conclusions: 7 T DESS imaging allows direct assessment of cervical nerve root compression in patients with radiculopathy, with a better prediction of sensory or motor dysfunction than standard clinical MRI. Diagnostic confidence and image quality of 7 T DESS were superior to 3 T DESS., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Intraoperative 2D fluoroscopy is often performed for repositioning and implant control. However, this does not always provide the details needed to reliably detect joint steps or incorrect repositioning. Over the last few years, intraoperative 3D imaging has been established and further developed. Multiple studies demonstrate an advantage and better intraoperative control through 3D imaging. Examples are the upper ankle, the proximal tibia and the distal radius; the rates of intraoperative revisions with digital volume tomography (DVT) are between 20-30%. Technical advancements, such as metal artifact reductions, automated plane setting, automated screw detection, and robotic DVT devices, facilitate intraoperative operation, shorten surgical time, and provide improved image quality. By processing the data sets in the form of an immersive, computer-simulated image in terms of "augmented reality" (AR), increased precision can be achieved intraoperatively while reducing radiation exposure. The implementation of these systems is associated with costs, which are offset by cost savings from avoided revisions. Adequate counter-financing is still lacking at the present time. Intraoperative 3D imaging represents an important tool for intraoperative control. The current data situation makes it necessary to address the routine use of 3D procedures, especially in the joint area. The indications are becoming increasingly broader. Technical innovations such as robotics and AR have significantly improved 3D devices in recent years and offer high potential for integration into the OR., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Despite its versatile applicability the intraoperative use of a mobile C‑arm is often problematic and potentially associated with increased radiation exposure for both the patient and the personnel. In particular, the correct positioning for adequate imaging can become a problem as the nonsterile circulating nurse has to coordinate the various maneuvers together with the surgeon without having a good view of the surgical field. The sluggishness of the equipment and the intraoperative setting (sterile borders, additional hardware, etc.) pose further challenges. A light detection and ranging (LIDAR)-based assistance system shows promise to provide accurate and intuitive repositioning support as part of an initial series of experimental trials. For this purpose, the sensors are attached to the C‑arm base unit and enable navigation of the device in the operating room to a stored target position using a simultaneous localization and mapping (SLAM) algorithm. An improvement of the workflow as well as a reduction of radiation exposure represent the possible potential of this system. The advantages over other experimental approaches are the lack of external hardware and the ease of use without isolating the operator from the rest of the operating room environment; however, the suitability for daily use in the presence of additional interfering factors should be verified in further studies., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

X-ray-based micro-computed tomography (micro-CT) is a largely non-destructive imaging method for the visualisation and analysis of internal structures in the ex vivo eye and affords high resolution. In contrast to other high-resolution imaging methods, micro-CT enables spatial recording of larger and more complex tissue structures, such as the anterior chamber of the eye. Special contrasting methods help to enhance the absorption properties of soft tissue, that is otherwise only weakly radiopaque. Critical point drying (CPD), as primarily used in scanning electron microscopy, offers an additional tool for improving differential contrast properties in soft tissue. In the visualisation of intraosseous soft tissue, such as the efferent lacrimal ducts, sample treatment by decalcification with ethylenediaminetetraacetic acid and subsequent CPD provides good results for micro-CT. Micro-CT can be used for a wide range of questions in 1. basic research, 2. application-related studies in ophthalmology (e.g. evaluation of the preclinical application of microstents for glaucoma treatment or analysis of the positioning of intraocular lenses) but also 3. as a supplement to ophthalmological histopathology., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht./The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Objective: Computer navigation is used in patients with spine fractures to optimize the accuracy of pedicle screws and thereby reduce intra- and postoperative complications, such as injuries to vessels, nerves and accompanying structures. In addition, the ideal screw length and diameter for each pedicle can be detected to ensure optimal stability., Indications: Intraoperative navigation is suitable for the treatment of spine fractures, which require dorsal stabilization or fusion. It is primarily used for dorsal procedures ranging from the cervical to lumbar/sacral spine., Contraindications: Computer navigation relies on rigid fixation of the dynamic reference base (DRB) at the spinous process. Failure of DRB fixation is the major contraindication for navigation in the spine., Surgical Technique: After acquisition of an intraoperative three-dimensional (3D) scan, a digital relation between the anatomy and the 3D scan is established with the navigation system and its infrared camera. Pedicle screws are planned percutaneously with a calibrated pointer. In the next step K‑wires (or screws) are implanted after the pedicles are drilled with a calibrated drill guide. After implantation, an additional 3D scan is performed to verify accurate K‑wire placement., Postoperative Management: Postoperative management does not differ compared to nonnavigated procedures., Results: Intraoperative navigation in combination with modern imaging systems leads to very high accuracy for pedicle screws. Immediate intraoperative control of K‑wires as well as screws and fracture reduction can avoid revision surgery. Image guidance can reduce radiation exposure for the surgical team., (© 2022. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Background: Recently introduced MRI techniques offer improved image quality and facilitate examinations of patients even when artefacts are expected. They pave the way for novel diagnostic imaging strategies in neuroradiology. These methods include improved 3D imaging, movement and metal artefact reduction techniques as well as Dixon techniques., Methods: Narrative review with an educational focus based on current literature research and practical experiences of different professions involved (physicians, MRI technologists/radiographers, physics/biomedical engineering). Different hardware manufacturers are considered., Results and Conclusions: 3D FLAIR is an example of a versatile 3D Turbo Spin Echo sequence with broad applicability in routine brain protocols. It facilitates detection of smaller lesions and more precise measurements for follow-up imaging. It also offers high sensitivity for extracerebral lesions. 3D techniques are increasingly adopted for imaging arterial vessel walls, cerebrospinal fluid spaces and peripheral nerves. Improved hybrid-radial acquisitions are available for movement artefact reduction in a broad application spectrum. Novel susceptibility artefact reduction techniques for targeted application supplement previously established metal artefact reduction sequences. Most of these techniques can be further adapted to achieve the desired diagnostic performances. Dixon techniques allow for homogeneous fat suppression in transition areas and calculation of different image contrasts based on a single acquisition., Key Points: · 3D FLAIR can replace 2 D FLAIR for most brain imaging applications and can be a cornerstone of more precise and more widely applicable protocols.. · Further 3D TSE sequences are increasingly replacing 2D TSE sequences for specific applications.. · Improvement of artefact reduction techniques increase the potential for effective diagnostic MRI exams despite movement or near metal implants.. · Dixon techniques facilitate homogeneous fat suppression and simultaneous acquisition of multiple contrasts.., Citation Format: · Sundermann B, Billebaut B, Bauer J et al. Practical Aspects of novel MRI Techniques in Neuroradiology: Part 1-3D Acquisitions, Dixon Techniques and Artefact Reduction. Fortschr Röntgenstr 2022; 194: 1100 - 1108., Competing Interests: Christian Mathys: Consulting and lecturing for Siemens on behalf of the employer (Evangelisches Krankenhaus Oldenburg).The other authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Artificial intelligence (AI) is playing an increasing role in radiological imaging in orthopaedics and trauma surgery. The algorithms available to date are predominantly used in the detection of (occult) fractures and in length and angle measurements in conventional X‑ray images. However, current AI solutions also enable the analysis and pattern recognition of CT datasets, e.g. in the detection of rib or vertebral body fractures. A special application is EOS™ (ATEC Spine Group, Paris, France), which enables a 3‑D simulation of the axial skeleton and semi-automatic length and angle calculations based on a digital 2‑D X‑ray image. In this paper, the current spectrum of AI applications for orthopaedics and trauma surgery is presented and discussed., (© 2022. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Due to the optimisation of conservative treatment, the improvement of imaging methods and the continuous development of surgical techniques, the borders of resectability in liver surgery have changed significantly in recent decades.Thanks to numerous technical developments, in particular three-dimensional segmentation, preoperative planning and orientation during the operation itself, can now be facilitated, especially in complex procedures.New technologies such as 3D printing as well as virtual and augmented reality offer additional display options for the patients' individual anatomy. Various intraoperative navigation options are intended to make preoperative planning available in the operating room in order to increase patient safety.This review article is intended to provide an overview of the current state of available technologies and an outlook into the operating theatre of the future., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Background: When using mobile 3D C-arms, impairments in image quality occur due to artefacts caused by metal implants as well as to the limited field of view. To avoid these restrictions, special computed tomography devices were designed, in order to improve image quality and to meet requirements for intraoperative usage., Objectives: To analyse practicability and benefits of a mobile intraoperative CT device (Airo, Brainlab, Munich, Germany) on the basis of several parameters that were obtained during a 40-month period., Materials and Methods: All procedures that were performed with usage of intraoperative CT between January 2017 and April 2020 were analysed with respect to anatomical region, count of scans, duration of scans, consequences drawn from the scans and use of navigation., Results: 354 CT-scans were performed in 171 patients (mean 2.07 [1 - 6] scans per procedure). 47.81% of the procedures were spinal, 52.19% affected the pelvis. 83% of the procedures were navigated. In 22% of patients, improvement in implant placement or reduction was achieved; in most patients (55%), a guidewire for pedicle screws was corrected. The mean scan duration was 10.33 s (3.54 - 21.72)., Conclusions: Use of intraoperative CT was reliable and helpful. Integration in OR standards requires more effort than mobile 3D C-arms. Image quality was outstanding for intraoperative conditions and allowed proper assessment of implant placement and reduction in all cases. Due to the high financial outlay of the system and the good image quality of 3D C-arms in the extremities, we assume that this procedure can be applied in intraoperative CT in traumatological cases in spinal and pelvic surgery in high-level trauma centres., Competing Interests: One of the authors received lecture fees from Brainlab AG./Einer der Autoren hat Vortragshonorare der Brainlab AG erhalten., (Thieme. All rights reserved.)

Often, midfacial defects are not only relevant regarding functional aspects but also esthetics of such congenital or acquired deformities impair significantly the patients' quality of life. Reconstructions of the midface do not only include replacing lost or non-developed tissue but moreover to achieve predictable results with regard to esthetics as well as function for the individual patient. Digital planning modalities including different surface and volume data in combination with modern additive manufacturing techniques for biomodel and implant production and intraoperative support by using real and virtual 3D volume data for navigation and intraoperative imaging, but also securing the outcome based on postoperative analysis have been implemented in modern midface reconstruction and represent new standards for medical care. The objective of this paper is to describe modern options of patient-specific midfacial reconstruction with integration of computer-assisted planning and production techniques., Competing Interests: Prof. Gellrich und Dr. Rahlf haben Vortragstätigkeiten für Gebrüder Martin GmbH mit Honorarvergütung., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)

Aim: The aim of this study was to compare transrectal two-dimensional (2D) and three-dimensional (3D) ultrasound examination with regards to required time and accuracy of fetal sex determination in early pregnant mares., Materials and Methods: For this purpose 47 mares were examined transrectally once between days 58 and 115 of gestation. Initially, the fetal sex was determined by identifying the location of the genital tubercle (GT) or external genitalia using 2D-ultrasound. Subsequently, the ultrasound machine was switched to 3D-mode to obtain images for later computer-based evaluation., Results: The gestational period between days 58 and 79 of pregnancy was the most appropriate time for sex determination with 77 % (2D and first 3D evaluation) correct diagnoses. The accuracy of the sex determination could be increased by about 16 % by a second evaluation of the 3D-images in a minimum time interval of 2 weeks. For each mare the additional time needed to perform the 3D-examination and to assess the 3D-images was approximately 6-7 minutes., Conclusion and Clinical Relevance: This study demonstrates that the accuracy of transrectal fetal gender determination is higher by using 3D-mode compared to the 2D-ultrasound. For experienced examiners however, 3D ultrasound technology does not offer any decisive advantages and is also more time-consuming., Competing Interests: Die Autoren bestätigen, dass kein Interessenkonflikt besteht., (© Georg Thieme Verlag KG Stuttgart · New York.)

Aim:  Assessment of the visualization of titanium and ceramic dental implants using various isotropic three-dimensional magnetic resonance imaging (MRI) methods., Materials and Methods:  21 dental implants (7 ceramic, 14 titanium) were scanned in vitro with a spatially isotropically resolved three-dimensional gradient echo (FFE), a turbo spin echo (SE) and an ultra-short-echo time (UTE) imaging technique. The resulting absolute volumes of the implants were quantified and the relative error to the theoretical volume was calculated., Results:  Ceramic implants and their periphery could be displayed well in all cases. The observed mean relative error results were 5.4 ± 2.3 % (UTE) to 6.5 ± 4.3 % (FFE). No significant difference was observed between the investigated MRI methods. The transition between implant and surrounding agarose could be shown in all cases without artifacts. Titanium implants resulted in mean relative errors between 1314 ± 350 % (FFE) and 2157 ± 810 % (SE). Here, significant differences were observed between the FFE and the SE and between the UTE and the SE sequence. The periphery of the implants could not be displayed in any case., Conclusion:  Use of the MRI technique for the diagnosis of peri-implantitis, the assessment of anatomical structures and planning of dental implantation is currently very limited but could be used more frequently, provided there are no disturbing or imaging-disturbing materials in the region of interest. MRI technology is not suitable in case of titanium implants. When using ceramic implants, MRI technology is an option., Key Points:   · MRI allows the artifact-free depiction of dental ceramic implants.. · Titanium implants cause the greatest relative errors in SE techniques.. · The UTE technique shows no significant improvements with respect to artifact behavior over the FFE technique.., Citation Format: · Geibel M, Gelißen B, Bracher A et al. Artefakt-Verhalten von dentalen Keramik- und Titanimplantaten im MRT. Fortschr Röntgenstr 2019; 191: 433 - 441., Competing Interests: Disclosure The authors report no conflicts of interest in this work., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background: Three-dimensional (3-D) endoscopic optics use 2 cameras to simulate the different perspectives of the right and left eye, creating the illusion of spatial depth. Optimised orientation as well as improved hand-eye coordination compared to 2-D-optics could be proven in standardised test setups (black box) and in laparoscopic use. This retrospective study examines whether these results can also be applied to thoracoscopic vertebral body replacement at the thoracolumbar junction., Hypotheses: 1. Ventral vertebral body replacement using 3-D-thoracoscopy results in a shorter operation time than with 2-D-thoracoscopy. 2. Perioperative blood loss is less, due to better spatial orientation (faster haemostasis) and reduced tissue laceration., Material and Methods: 29 patients met the inclusion criteria of this retrospective study. Between 08 - 2012 and 08 - 2017, all of these received ventral thoracoscopic vertebral replacement at the thoracolumbar junction (Th11 to L2). Patients with additional anterior procedures (e.g. anterolateral plate) were excluded. Perioperative data such as blood loss, duration of surgery and length of hospital stay were analysed. Conventional 2-D-optics were used in n = 14 patients and 3-D-optics in 15 patients. Aesculap EinsteinVision ® 2.0 was used as the 3-D-optics. Statistical significance was calculated using Student's t-test., Results: The most common diagnosis was a L1 fracture (n = 18, 62%). Mean OR time was 24 minutes shorter in the 3-D group (149 ± 29, 107 - 198 min) than in the 2-D group (173 ± 39, 125 - 260 min), but this difference was not significant. Total perioperative blood loss in the 3-D group was significantly lower than in the 2-D group (**p = 0.043). Proportional intraoperative blood loss in the 3-D group was also lower (mean around 115 ml), but not significantly so. Significantly lower values were found for the delivery rate of the thoracic drainage in the 3-D group (248 vs. 560 ml, *p = 0.195). Inpatient stay with the 3-D group was on average 1.5 days (d) shorter (8.7 d for the 3-D group, 10.2 d for the 2-D group) but this difference was not significant (p = 0.27)., Conclusion: Thoracoscopic-assisted vertebral body replacement at the thoracolumbar junction is a safe and reliable surgical procedure using conventional 2-D-optics or the new 3-D-optics. Both methods allow thoracoscopic vertebral body replacement in comparable operation times but in our study the 3-D group presented with significantly lower postoperative blood loss. Due to the small number of cases and because of the retrospective design, the present study is considered to be a pilot study only., Competing Interests: The authors declare they have no conflicts of interest./Die Autoren geben an, dass kein Interessenkonflikt besteht., (Georg Thieme Verlag KG Stuttgart · New York.)

Background and Objective: Acetabular cup orientation, consisting of pelvic positioning, version and inclination, can influence short-term and long-term results after total hip arthroplasty (THA). The radiographic measurement of acetabular cup inclination represents an indicator of quality for the EndoCert certification in Germany. The purpose of this study was to determine the intrarater and interrater reliability of radiographic measurements of acetabular cup inclination after THA., Material and Methods: In this study four independent investigators with different levels of expertise retrospectively performed measurements on radiograms (anteroposterior pelvic radiogram) from 99 patients. The intraclass correlation coefficient (ICC) and Pearson's correlation coefficient were determined and were considered statistically significant with r > 0.8 and p < 0.05., Results and Conclusion: A high correlation was found for both intrarater and interrater reliability based on determination of Pearson's correlation coefficient and the ICC with r > 0.9 and p < 0.001 for all measurements. Based on these results the radiographic measurement of acetabular cup inclination can be considered as a simple measuring tool with high intrarater and interrater reliability. As cup orientation consists of inclination, version and positioning, the exclusive measurement of cup inclination for radiological quality assessment needs to be discussed critically.

Optical coherence tomography (OCT) enables noninvasive high-resolution 3D imaging of the human retina, and thus plays a fundamental role in ophthalmology. Via OCT examination, even subtle retinal changes can be captured, which occur in very early stages of different diseases (e.g., glaucoma, diabetes mellitus, or age-related macular degeneration). Yet, analyzing the resulting data is challenging. Conventionally, OCT data are strongly aggregated via automated methods. While this reduces the amount of information to be analyzed, it also makes it difficult, if not impossible, to identify small and localized retinal changes. This might lead to wrong diagnoses, since these methods do not account for patient-specific characteristics. We address this problem by providing new and efficient visual-interactive methods. Particularly, we introduce dedicated visualizations that show different aspects of the data. In addition, we support patient-specific selections of relevant data regions. Selected regions are emphasized, or separately visualized to inspect retinal substructures in detail. By visually comparing the regions to reference data, even very small retinal changes can be detected. We demonstrate the utility of our approach by applying it to data of a study with pediatric patients suffering from diabetes mellitus type 1. Our results show that visual-interactive methods indeed help to analyze subtle retinal changes and, thus, support the diagnosis of diseases in an early stage., Competing Interests: Interessenkonflikt: Die Autoren geben an, dass kein Interessenkonflikt besteht., (Georg Thieme Verlag KG Stuttgart · New York.)

Background: Current computational neuroanatomy focuses on morphological measurements of the brain using standard magnetic resonance imaging (MRI) techniques. In comparison quantitative MRI (qMRI) typically provides a better tissue contrast and also greatly improves the sensitivity and specificity with respect to the microstructural characteristics of tissue., Objective: Current methodological developments in qMRI are presented, which go beyond morphology because this provides standardized measurements of the microstructure of the brain. The concept of in-vivo histology is introduced, based on biophysical modelling of qMRI data (hMRI) for determination of quantitative histology-like markers of the microstructure., Results: The qMRI metrics can be used as direct biomarkers of the microstructural mechanisms driving observed morphological findings. The hMRI metrics utilize biophysical models of the MRI signal in order to determine 3‑dimensional maps of histology-like measurements in the white matter., Conclusion: Non-invasive brain tissue characterization using qMRI or hMRI has significant implications for both scientific and clinical applications. Both approaches improve the comparability across sites and time points, facilitate multicenter and longitudinal studies as well as standardized diagnostics. The hMRI is expected to shed new light on the relationship between brain microstructure, function and behavior both in health and disease. In the future hMRI will play an indispensable role in the field of computational neuroanatomy.

After the discovery of skeletonized human remains, the estimation of stature is an important element of the so-called "biological profile". Typically, long bone lengths are used in regression formulas. If long bones are not available, predictions of stature cannot be made. Human skulls are often the subject of forensic osteological examination, sometimes even detached. Therefore, it seems reasonable to search for skull measurements that have a sufficiently good correlation to stature. The aim of the study presented was to measure odonto-stomatological parameters using post-mortem CT data to check whether the esti- mation of stature was possible on this basis. Three classic tooth dimensions (MD, BL, ZL), two diagonal tooth dimensions (MBDL, DBML) first described by Lund and Mörnstad in 1999, two tooth dimensions defined for the first time in this study (MKDO, DKMO), the mesiodistal index (MDS) and also the palatal arch dimensions (arch length, arch width, molar length and dental length) - each at maxilla and mandible - were digitally measured on a total of 799 teeth of 48 virtual 3-D-reconstructed skulls (33 males and 15 females). For most of the aforementioned measurements no statistically significant relation to stature was found. There were positive correlations by Pearson at a significance level of 99 % (2-sided) at three measurements: ZL 15, MKDO 14 and MKDO 15. Positive correlations by Pearson at a significance level of 95 % (2-sided) could be determined for eight measurements, but an applicable regression formula could not be calculated for any of the parameters. Despite a statistical correlation of a few teeth parameters with body length, they must be considered unsuitable for estimating stature.

Modern intraoperative techniques of visualization are increasingly being applied in general and visceral surgery. The combination of diverse techniques provides the possibility of multidimensional intraoperative visualization of specific anatomical structures. Thus, it is possible to differentiate between normal tissue and tumor tissue and therefore exactly define tumor margins. The aim of intraoperative visualization of tissue that is to be resected and tissue that should be spared is to lead to a rational balance between oncological and functional results. Moreover, these techniques help to analyze the physiology and integrity of tissues. Using these methods surgeons are able to analyze tissue perfusion and oxygenation. However, to date it is not clear to what extent these imaging techniques are relevant in the clinical routine. The present manuscript reviews the relevant modern visualization techniques focusing on intraoperative computed tomography and magnetic resonance imaging as well as augmented reality, fluorescence imaging and optoacoustic imaging.

Background: Osteoporosis is still underdiagnosed in Germany., Objectives: Is it possible to detect osteoporosis on the basis of a cone-beam computed tomography image of the mandible and several measuring methods?, Materials and Methods: Sixteen cone-beam computed tomography (CBCT) images from patients of the dental clinic at the University of Ulm were reinvestigated. When the CBCT images were processed the subjects were at least 55 years old, and the mandible was completely mapped on the image. Furthermore, a dual-energy X‑ray absorptiometry scan or a CT bone mineral density test was required for every subject. The subjects were divided into an osteoporosis group and a control group. The computed tomography mental index (CTMI), the computed tomography mandibular index superior (CTI[S]) and the computed tomography mandibular index inferior (CTI[I]) were deployed for comparison of the groups. In the first instance a comparison of the osteoporosis and control groups was made for both male and female subjects. Subsequently, only the images of the female subjects were compared to each other., Results: A possibility for osteoporosis can be expressed at CTMI values located < 3.0 mm. As well for CTI(S) < 0.18 and CTI(I) < 0.23. There arises a 66.7 % sensitivity and 70 % specificity for the mixed subject group and an 80 % sensitivity and 57.1 % specificity for the female subject group for CTMI and CTI(S). Furthermore, there are 50.0 % sensitivity and 70 % specificity for the mixed subject group and 60.0 % sensitivity and 57.1 % specificity for the female subject group for the CTI(I)., Conclusion: CTMI, CTI(S) and CTI(I) are only suitable for osteoporosis detection to a limited extent.

Background: Treatment of type II fractures of the odontoid process is still controversial. Besides conservative treatment, there are surgical options, including anterior screw fixation, as first described by Böhler and Magerl, or procedures using a dorsal approach. Many authors prefer dorsal fusion of C1 and 2, due to the reliable, biomechanical stability. In this context, pedicle screw fixation, as described by Harms, and transarticular screw fixation of the atlantoaxial joints, as described by Magerl, have to be mentioned. With the use of intraoperative fluoroscopic navigation, the risk of neurovascular lesions caused by abortive drilling or malposition of screws has been significantly decreased. In 1993, Eysel and Roosen established a subclassification of type II fractures of the odontoid process and gave treatment recommendations for each of the three subtypes. While there was an outcome for type A and B fractures treated by anterior screw fixation, the authors recommended performing dorsal stabilisation at type C fractures. Indication: In accordance with the recommendations of Eysel and Roosen, an 82 year old man, suffering from a type II C fracture of the odontoid process, underwent navigated, transarticular screw fixation of C1 and C2. Method: Once the 3D-fluoroscopy scan had been performed, the correct drilling direction in the axial, coronary and sagittal views of C1 and 2 was found using the navigated drillguide. After K-wires had been inserted in this direction on both sides, a second 3D-scan was performed to recontrol placement of the K-wires. Cannulated screws were introduced and the rods were installed, bearing the atlas hook to fixate the posterior atlas. Conclusion: In summary, dorsal, transarticular fusion of C1 and C2 is a successful treatment option, rarely leading to complications and is accompanied by reduced radiation exposure to the operating team., (Georg Thieme Verlag KG Stuttgart · New York.)

This article presents the case of a high-grade deformity of the thoraco-lumbar spine. The patient suffered from a sarcoma that was radically resected. Due to adjuvant radiation, the patient suffered from a radiation injury with chronic fistula. In a two-stage approach, the deformity was corrected by a closing-wedge osteotomy of L3 with elongation of the present dorsal spondylodesis (Th10-L4) to Th8 and the iliac bone. Soft-tissue reconstruction was achieved by a free latissimus dorsi flap that was anastomosed to an axillary arterio-venous loop. The presented interdisciplinary approach allowed an almost complete correction of the deformity and stable soft-tissue coverage.

Background: Intraoperative imaging during spinal interventions has experienced significant developments over the last two decades. By the introduction of flat screen detectors, 3D imaging has been made possible and easier and by developing compact and mobile systems computed tomography can even be used in the operating theater., Objective: Presentation of modern intraoperative 3D imaging and navigation in spinal surgery., Material and Methods: The techniques of intraoperative 3D imaging and navigation during spinal procedures are presented based on the currently available literature and own experiences at a German national spine and trauma center., Results: The use of flat panel detectors and the possibility of 3D visualization nowadays substantially facilitate the use of navigation and allow certain control of surgical results even during the intervention. Radiation exposure of the whole team in the operating theater can be significantly reduced by the new techniques., Conclusion: The advantages of intraoperative 3D imaging with a clear improvement of visualization for spinal surgeons and the certain control of materials at the end of the operation are obvious. Even the use of navigation has been greatly simplified and can therefore lead to an even greater precision and less radiation exposure. There are even more sophisticated developments, such as operation suites and intraoperative computed tomography but these are initially reserved for selected centers.

Background: The results and immediate consequences of intraoperative three-dimensional (3D) imaging in the treatment of AO classification type C fractures of the distal radius, the tibial head and the tibial pilon were analyzed and compared with published results on general intraoperative revision rates following intraoperative 3D-imaging., Methods: In this retrospective study 279 patients with AO type C fractures of the distal radius (n = 84), tibial head (n = 109) and tibial pilon (n = 86) who underwent intraoperative 3D-imaging were included. The findings of the 3D-imaging and the intraoperative revision rates were analyzed and compared with previously published results of our working group., Results: In 70 out of 279 patients (25 %) an intraoperative revision was carried out following 3D-imaging. The revision rates were 15 % for fractures of the distal radius, 27 % for fractures of the tibial head and 32 % for fractures of the tibial pilon. The most common reason for immediate intraoperative revision was the necessity for improved repositioning due to a remaining step in the articular surface in 51 out of 279 patients (18%)., Conclusion: Intraoperative revision rates following 3D-imaging increased with the severity of the injury pattern. Intraoperative 3D-imaging should be routinely used in the treatment of fractures of the tibial head, tibial pilon and even in comminuted distal radius fractures due to the high intraoperative revision rates found in the present study. Alternatively, a postoperative computed tomography (CT) control should be performed.

Intraoperative 3D imaging has a marked impact on the surgical treatment of articular fractures. In theory, insufficient reduction of fracture fragments and malpositioning of implants can be corrected in the same session so that unnecessary secondary imaging and revision surgery can be avoided. Current evidence on the accuracy of 3D scans, however, relies on heterogeneous preclinical data and must be interpreted with caution. Every fourth 3D scan seems to lead to a repositioning of fracture fragments or implants, despite unproven sensitivity and specificity. The interaction between diagnostic accuracy and therapeutic consequences needs exploration before any conclusions on the (additional) benefits of intraoperative 3D imaging can be drawn.

We report the case of a patient with episodic rotational vertigo for years. Ear symptoms were negated. The clinical diagnosis was not clear - Menière's disease, vestibular migraine and recurrent vertigo after vestibular neuritis all qualified for differential diagnoses. A locally enhanced inner-ear MRI established clarity by showing an endolymphatic hydrops in the vestibulum. Besides the classical triad of Menière's disease there are other clinical appearances of endolymphatic hydrops, which can be visualized with inner-ear MRI.

Atrial arrhythmias are frequently encountered in patients with congenital heart disease (CHD) with or without corrective surgery and respond to pharmacological therapies with only limited success. This review describes the technologies currently available for performing successful ablation procedures in this very complex patient cohort. In addition to an understanding of the underlying anatomy, which can be supplemented by 3D imaging with the aid of magnetic resonance imaging (MRI) or computed tomography (CT), the choice between the different 3D mapping systems (sequential versus simultaneous) is presented. Finally, conventional manual navigation is compared with magnetic navigation and then discussed with regard to the respective arrhythmias encountered with the different forms of CHD.

A 64-year-old female patient complained of a bilateral reduction in vision. The foveal reflex was remarkable bilaterally and optical coherence tomography (OCT) demonstrated the absence of a foveal depression. After exclusion of possible diseases foveal hypoplasia was diagnosed. This rare alteration of the fovea should not be mistaken for foveal edema. A volume scan with a narrow grid is advisable to avoid a misinterpretation.

Background: Modern chemotherapy regimen for colorectal cancer results in complete radiologic remission in a substantial number of cases. However, these "vanished liver metastases" (VLM) often contain vital tumor cells, which mandates the resection of such lesions. In these cases, intraoperative identification of VLM can be challenging, in particular in laparoscopic approaches. We describe the first laparoscopic computer-assisted 3D-navigated resection of a VLM., Case Report: A 60-year-old patient with a synchronous liver metastasis (segment IVb) of sigmoid colon cancer (T4 N1 M1) was referred to our center for elective liver resection after laparoscopic sigmoid resection and systemic chemotherapy (FOLFIRI/Panitumumab). The metastasis was not visible anymore on preoperative CT or sonography. Thus, a 3 D reconstruction of the liver was performed. The size of the initial metastasis (before chemotherapy) was transferred into the current CT. A computer-assisted 3D-navigated laparoscopic resection of the metastasis was performed on these fused images. The metastasis was also not clearly visible upon intraoperative ultrasound. Histology of the resected specimen revealed a 0.5 cm metastasis with predominantly vital tumor cells (regression degree 4 of Rubbia-Brandt) and a sufficient resection margin of at least 7 mm. The postoperative course was uneventful., Conclusion: Computer-assisted 3D-navigation enabled a safe oncologic resection of a vanished liver metastasis after chemotherapy. This technique was particularly helpful due to the limited haptic feedback of laparoscopic surgery. Further studies are necessary to verify the clinical benefit of computer assisted 3D-navigated liver surgery., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background: Digital planning of implants is in most cases conducted prior to surgery. The virtual implant planning system (VIPS) is an application developed for mobile C-arms, which assists the virtual planning of screws close to the joint line during surgery for treatment of distal radius fractures with volar plate osteosynthesis. The aim of this prospective randomized study was to acquire initial clinical experiences and to compare the VIPS method with the conventional technique., Method: The study included 10 patients for primary testing and 30 patients with distal radius fractures of types A3, C1 and C2, divided in 2 groups. In the VIPS group, after placement of the plate and fracture reduction, a virtual 3D model of the plate was matched with the image of the plate from the fluoroscopic acquisition. Next, the length and position of the screws close to the joint line were planned on the virtual plate. The control group was treated with the same implant in the conventional way. Data were collected regarding screw replacement, fluoroscopy and operating room (OR) times., Results: The VIPS group included six A3, one C1 and eight C2 fractures, while the control group consisted of six A3 and nine C2 fractures. Three screws were replaced in the VIPS group and two in the control group (p = 0.24). The mean intraoperative fluoroscopy time of the VIPS group amounted to 2.58 ± 1.38 min, whereas it was 2.12 ± 0.73 min in the control group (p = 0.26). The mean OR time in the VIPS group was 53.3 ± 34.5 minutes and 42.3 ± 8.8 min (p = 0.23) in the control group., Conclusion: The VIPS enables a precise positioning of screws close to joint line in the treatment of distal radius fractures; however, for routine use, further development of the system is necessary.

The new technique of optical coherence tomography (OCT) angiography allows a non-invasive reconstruction of the three-dimensional structure of the total retinal and choroidal vascularization within seconds. There are still limitations caused by movement artefacts, superimposition of superficial retinal vessels at the retinal pigment epithelium (RPE) level and insufficient three-dimensional imaging modalities. Initial experiences with this new method and especially the correlation with the current standard diagnostic procedure of fluorescein angiography show that new information can be obtained regarding specific vascular and neovascular changes. For three-dimensional neovascular changes, such as those found in exudative age-related macular degeneration (AMD,) a more sophisticated diagnostic analysis strategy must be specifically developed. Initial experiences demonstrate that the differentiation into the various types of choroidal neovascularization (CNV) by fluorescein angiography, specifically for type 1 (occult) and type 2 (classical) can also be visualized by OCT angiography. Furthermore, the new technology provides additional information on the choroidal and outer retinal changes associated with this disease, which may result in a better understanding of the underlying pathology.

The application spectrum of the EOS imaging acquisition system is versatile. It is especially useful in the diagnostics and planning of corrective surgical procedures in complex orthopedic cases. The application is indicated when assessing deformities and malpositions of the spine, pelvis and lower extremities. It can also be used in the assessment and planning of hip and knee arthroplasty. For the first time physicians have the opportunity to conduct examinations of the whole body under weight-bearing conditions in order to anticipate the effects of a planned surgical procedure on the skeletal system as a whole and therefore on the posture of the patient. Compared to conventional radiographic examination techniques, such as x-ray or computed tomography, the patient is exposed to much less radiation. Therefore, the pediatric application of this technique can be described as reasonable.

Background and Purpose: The Oculus Pentacam® is one of the most commonly used devices in ophthalmology for assessment of the anterior eye segment. The purpose of this study was to determine the reproducibility of the corneal power as measured by the Pentacam® in a normal population., Methods: We enrolled 25 eyes of 25 subjects aged between 13 and 68 (46.7 ± 21.7) years, within a spherical equivalent from - 4 D to + 4 D and refractive cylinder up to 5 D and without notable pathologies or history of surgery. A sequence of 5 measurements was performed using the Pentacam®, the Zeiss IOLMaster® as well as an autorefractometer after (re-)positioning the patient's head and the measurement device. From the Pentacam® we collected power data for the corneal front and back surfaces, apical corneal thickness at apex and internal anterior chamber depth. From the IOLMaster®, we extracted corneal power data, and from the autorefractometer we obtained refractive power data of both cardinal meridians. For statistical analysis, we used Cronbach's α as a measure of reproducibility and Spearman's rank correlation test for correlation of data., Results: Pentacam® yields highly reproducible power data for both corneal surfaces, with Cronbach's α of greater than 0.97 for primary parameters (e.g. radii of curvature) and 0.9 for secondary parameters (e.g. vector components of astigmatism). Central corneal thickness and eccentricities of both surfaces as well as anterior chamber depth yielded highly reproducible values, with α of ≥ 0.97. Corneal power derived from IOLMaster® and objective refraction extracted from the autorefractometer yielded α values of around 0.9. Mean corneal power of Pentacam® and IOLMaster® correlated well, but there was no correlation to spherical equivalent. Astigmatism values from Pentacam® and IOLMaster® correlated well with each other and with refractive cylinder., Conclusion: Our results indicate that measurements of anterior segment using the Pentacam® yield highly reproducible results in a normal population without major pathologies of the anterior eye segment., (Georg Thieme Verlag KG Stuttgart · New York.)

Background: Scoliosis is a complex three-dimensional deformity of the spine, which usually occurs during childhood and adolescence. Up to now, whole spine X-rays have been the therapeutic gold standard in the diagnosis and follow-up of scoliosis., Aim: This review gives a brief overview of the history, technical background and possible fields of use for video-rasterstereography, Methods: Alternative measurement systems have been developed over the past few years for the treatment of scoliosis, because of the risk of radiation exposure of X-rays. The rasterstereographic system Formetric (Diers International GmbH, Schlagenbad) allows a radiation-free, three-dimensional analysis of the back surface and the spine., Outlook: Even dynamic measurements can now be conducted with this rasterstereographic system, which will help to further understand and analyze the human spine.

After edovascular repair of infrarenal aortic aneurysms (EVAR) endoleaks may occur necessitating further therapy. Therefore a reliable method for follow-up imaging after EVAR for detection and control of endoleaks is of high importance. Contrast-enhanced sonography (CEUS) does not require the application of nephrotoxid contrast media and does not stress the patient. CEUS is increasingly used and enables a quick, non-invasive follow-up examination for patient after EVAR. In addition, interventions as therapy for endoleaks may be executed using ultrasound. Initial experience with CEUS-guided aortic stenting shows that the amount of contrast media as well as X-ray time may be reduced., (Georg Thieme Verlag KG Stuttgart · New York.)

Intravascular ultrasound has been established as the gold standard for analyzing alterations in coronary artery atherosclerosis during monitoring investigations. Cross-sectional imaging can be used to visualize the area of the lumen and the vessel size and the plaque size as the difference between them. New technology allows the 3-D reconstruction of the volume for prespecified vessel segments using specific algorithms. Investigations on the natural course demonstrated predominantly progression. Even regression of coronary atherosclerosis can be visualized and quantified. Regression can only be expected when the level of low-density lipoprotein (LDL) cholesterol is below the critical level of 75 mg/dl. Prospective randomized studies with highly effective statins showed that regression occurred in up to two thirds of patients when LDL cholesterol was below a cut-off of 78 mg/dl and was, therefore, very close to the threshold, which was calculated based on investigations of the natural course. Although the absolute values for plaque volume are in the range of 1 % over 1-2 years, it must be taken into consideration that coronary artery diseases are chronic diseases and a 1 % change per year will correspond to an enormous effect on plaque growth of coronary vessels. The great success of statins in reducing cardiovascular events is due to the possibility for reduction of progression and induction of regression. New developments in medication will be measured against the effectiveness of statins.

Background: The Heidelberg retinal tomography (HRT) is a technique that has been used for more than 20 years for glaucoma diagnostics and management. Many hundreds of scientific investigations have tested the reliability and accuracy of HRT for the early diagnosis of glaucoma and just as many studies can be found on the detection of progression in glaucoma. It is still one of the leading imaging systems for the detection and follow-up of glaucoma. Hardware and statistical methods implemented for progression detection have been regularly updated by the company and internationally known glaucoma specialists., Methods: Besides the analysis of stereometric parameters and trend analyses, the primary method for assessing glaucomatous change using the HRT is the topographic change analysis (TCA), a technique that compares the variability within a baseline examination to that between baseline and follow-up examinations.Furthermore, the flicker comparison enables detection of small topographic changes over time., Conclusion: The use of HRT does not replace clinical examinations but facilitates the assessment and management of glaucoma depending on observer experience. This imaging method will still have a significant value in the future for glaucoma diagnostics, with a special emphasis on assessment of progression.

Excellent morphological imaging of cartilage is now possible and allows the detection of subtle cartilage pathologies. Besides the standard 2D sequences, a multitude of 3D sequences are available for high-resolution cartilage imaging. The first part therefore deals with modern possibilities of morphological imaging. The second part deals with functional cartilage imaging with which it is possible to detect changes in cartilage composition and thus early osteoarthritis as well as to monitor biochemical changes after therapeutic interventions. Validated techniques such as delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and T2 mapping as well the latest techniques, such as the glycosaminoglycan chemical exchange-dependent saturation transfer (gagCEST) technique will be discussed.

Objectives: Permanent retention is currently the method of choice to stabilize orthodontic treatment results. Frequently, permanent retention schemes are adopted to prevent posttreatment changes in the esthetic zone of the anterior teeth. With increasingly prolonged times of intraoral device use, and retention to be provided in the maxilla despite limited space, the demands placed on well-planned and precise retainer positioning are becoming more exacting. The aim of the present study was to analyze the intraoral precision of lingual retainers made using computer-aided design and machining (CAD/CAM)., Materials and Methods: A custom manufacturer (Retaintechnology; Cologne, Germany) employing innovative CAD/CAM technology was commissioned to fabricate 16 lingual retainers. Following intraoral insertion using the manufacturer's recommended transfer system, impressions of the intraoral situations were taken and scanned for digitization. On this basis, the intraoral retainer positions were compared to the preceding virtual setups by superimposition with the manufacturer's datasets. Three-dimensional processing software (Geomagic Qualify 2012; Geomagic) was used to analyze the retainers, based on a total of 80 interproximal sites, for deviations from their planned positions along the horizontal (x-), sagittal (y-), and vertical (z-) axes. These deviations of the achieved from the intended positions were considered clinically relevant if ≥ 0.5 mm and, based on this premise, were subjected to a t-test with statistical software (Prism; GraphPad)., Results: The intraoral retainer positions were found to correlate closely with the preceding virtual setups (i.e., the positions as they had been planned by the custom manufacturer). Positional deviations were significantly less than 0.5 mm. They were very small in the horizontal and sagittal planes and moderately larger in the vertical plane., Conclusion: Highly precise intraoral results may be achieved by transferring three-dimensional virtual setups for lingual retainers to the actual patients. This CAD/CAM strategy of making retainers can offer high predictability even in anatomically demanding regions and in the presence of limited space.