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An auditory brainstem implant (ABI) attempts to restore hearing at patients with bilateral damaged hearing nerve. The optimal placement of the ABI is challenging even with available auditory measures on the brainstem. We present a visual guidance system that aims to assist during intraoperative ABI placement. As a starting point, a surgical probe is navigated and intuitively visualized in the microscope oculars. The system is developed using modular and agile software design techniques. In a usability study, the participants were able to detect invisible targets marked in a phantom image with a millimetric precision. To the best of our knowledge, this is the first time that this kind of visual guidance is presented. In the future, the system will be expanded with surgical instruments used for the ABI placement.

Simple Summary: Radiochemotherapy (RCT) in patients with locally advanced head and neck squamous cell carcinoma (HNSCC) causes side effects in healthy tissue such as the sternocleidomastoid muscle (SCM). These side effects depend on the interval between completion of RCT and restaging CT. For salvage surgery, the optimal time window for surgery is clinically postulated at between 6 and 12 weeks after completion of RCT. Thus, no extensive tissue fibrosis is to be expected. This interval is based on clinical studies exploring surgical complications. Studies directly exploring radiation-induced changes of the SCM in HNSCC patients are sparse. This study applied radiomics to quantify radiation-induced changes in the SCM and paravertebral musculature (PVM). In 98 locally advanced HNSCC patients, three radiomic key features (volume, mean positivity of pixels, uniformity) were analyzed in CT scans before and in the mean 8 weeks after treatment. No significant changes in radiomic key features were observed after adjustment for changes in body mass index (BMI). These data support the clinically postulated time window for salvage surgery of 6 to 12 weeks. Patients with locally advanced head and neck squamous cell carcinoma (HNSCC) frequently require primary radiochemotherapy (RCT). Despite intensity modulation, the desired radiation-induced effects observed in HNSCC may also be observed as side effects in healthy tissue, e.g., the sternocleidomastoid muscle (SCM). These side effects (e.g., tissue fibrosis) depend on the interval between the completion of RCT and restaging CT. For salvage surgery, the optimal time window for surgery is currently clinically postulated at between 6 and 12 weeks after completion of RCT. Thus, no extensive tissue fibrosis is to be expected. This interval is based on clinical studies exploring surgical complications. Studies directly exploring radiation-induced changes of the SCM in HNSCC patients are sparse. The present study quantified tissue alterations in the SCM and paravertebral musculature (PVM) after RCT, applying radiomics to determine the optimal time window for salvage surgery. Three radiomic key parameters, (1) volume, (2) mean positivity of pixels (MPP), and (3) uniformity, were extracted with mint LesionTM in the staging CTs and restaging CTs of 98 HNSCC patients. Of these, 25 were female, the mean age was 62 (±9.6) years, and 80.9% were UICC Stage IV. The mean restaging interval was 55 (±28; range 29–229) days. Only the mean volume significantly decreased after RCT, from 9.0 to 8.4 and 96.5 to 91.9 mL for the SCM and PVM, respectively (both p = 0.007, both Cohen's d = 0.28). In addition, the mean body mass index (BMI) decreased from 23.9 (±4.2) to 21.0 (±3.6) kg/m² (p < 0.001; Cohen's d = 0.9). The mean BMI decreased significantly and was correlated with the volume decrease for the SCM (r = 0.27; p = 0.007) and PVM (r = 0.41; p < 0.001). If t-test p-values were adjusted for the BMI decrease, no significant change in volumes for the SCM and PVM was observed (both p > 0.05). The present data support the clinically postulated optimal interval for salvage surgery of 6 to 12 weeks. [ABSTRACT FROM AUTHOR]

Simple Summary: Locally-advanced head and neck squamous cell carcinoma (HNSCC) is mainly defined by the presence of pathologic cervical lymph nodes (LNs). Radiologic criteria to classify LNs as pathologic or non-pathologic are shape-based. However, significantly more quantitative information is contained within images. This information could be exploited to classify LNs in patients with locally-advanced HNSCC by means of artificial intelligence (AI). The present work systematically reviews original articles that specifically explore the role of AI to classify LNs in locally-advanced HNSCC. Between 2001 and 2022, 13 retrospective studies were identified. AI's mean diagnostic accuracy for LN-classification was 86% (range: 43–99%). Consequently, all of the identified studies concluded AI to be a potentially promising diagnostic support tool for LN-classification in HNSCC. However, adequately powered, prospective, randomized control trials are urgently required to further assess AI's role in LN-classification in locally-advanced HNSCC. Locally-advanced head and neck squamous cell carcinoma (HNSCC) is mainly defined by the presence of pathologic cervical lymph nodes (LNs) with or without extracapsular spread (ECS). Current radiologic criteria to classify LNs as non-pathologic, pathologic, or pathologic with ECS are primarily shape-based. However, significantly more quantitative information is contained within imaging modalities. This quantitative information could be exploited for classification of LNs in patients with locally-advanced HNSCC by means of artificial intelligence (AI). Currently, various reviews exploring the role of AI in HNSCC are available. However, reviews specifically addressing the current role of AI to classify LN in HNSCC-patients are sparse. The present work systematically reviews original articles that specifically explore the role of AI to classify LNs in locally-advanced HNSCC applying Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines and the Study Quality Assessment Tool of National Institute of Health (NIH). Between 2001 and 2022, out of 69 studies a total of 13 retrospective, mainly monocentric, studies were identified. The majority of the studies included patients with oropharyngeal and oral cavity (9 and 7 of 13 studies, respectively) HNSCC. Histopathologic findings were defined as reference in 9 of 13 studies. Machine learning was applied in 13 studies, 9 of them applying deep learning. The mean number of included patients was 75 (SD ± 72; range 10–258) and of LNs was 340 (SD ± 268; range 21–791). The mean diagnostic accuracy for the training sets was 86% (SD ± 14%; range: 43–99%) and for testing sets 86% (SD ± 5%; range 76–92%). Consequently, all of the identified studies concluded AI to be a potentially promising diagnostic support tool for LN-classification in HNSCC. However, adequately powered, prospective, and randomized control trials are urgently required to further assess AI's role in LN-classification in locally-advanced HNSCC. [ABSTRACT FROM AUTHOR]

Purpose: The fiducial localization error distribution (FLE) and fiducial configuration govern the application accuracy of point-based registration and drive target registration error (TRE) prediction models. The error of physically localizing patient fiducials ( $${\hbox {FLE}}_\mathrm{patient}$$ ) is negligible when a registration probe matches the implanted screws with mechanical precision. Reliable trackers provide an unbiased estimate of the positional error ( $${\hbox {FLE}}_\mathrm{tracker}$$ ) with cheap repetitions. FLE further contains the localization error in the imaging data ( $${\hbox {FLE}}_\mathrm{image}$$ ), sampling of which in general is expensive and possibly biased. Finding the best techniques for estimating $${\hbox {FLE}}_\mathrm{image}$$ is crucial for the applicability of the TRE prediction methods. Methods: We built a ground-truth (gt)-based unbiased estimator ( $$\widehat{{\hbox {FLE}}_\mathrm{gt}}$$ ) of $${\hbox {FLE}}_\mathrm{image}$$ from the samples collected in a virtual CT dataset in which the true locations of image fiducials are known by definition. Replacing true locations in $${\hbox {FLE}}_\mathrm{gt}$$ by the sample mean creates a practical difference-to-mean (dtm)-based estimator ( $$\widehat{{\hbox {FLE}}_\mathrm{dtm}}$$ ) that is applicable on any dataset. To check the practical validity of the dtm estimator, ten persons manually localized nine fiducials ten times in the virtual CT and the resulting $${\hbox {FLE}}_\mathrm{dtm}$$ and $${\hbox {FLE}}_\mathrm{gt}$$ distributions were tested for statistical equality with a kernel-based two-sample test using the maximum mean discrepancy (MMD) (Gretton in J Mach Learn Res 13:723-773, ) statistics at $$\alpha =0.05$$ . Results: $${\hbox {FLE}}_\mathrm{dtm}$$ and $${\hbox {FLE}}_\mathrm{gt}$$ were found (for most of the cases) not to be statistically significantly different; conditioning them on persons and/or screws however yielded statistically significant differences much more often. Conclusions: We conclude that $$\widehat{{\hbox {FLE}}_\mathrm{dtm}}$$ is the best candidate (within our model) for estimating $${\hbox {FLE}}_\mathrm{image}$$ in homogeneous TRE prediction models. The presented approach also allows ground-truth-based numerical validation of $${\hbox {FLE}}_\mathrm{image}$$ estimators and (manual/automatic) image fiducial localization methods in phantoms with parameters similar to clinical datasets. [ABSTRACT FROM AUTHOR]

Objective. We questioned whether the position of the dynamic reference frame (DRF) influences the application accuracy in electromagnetically navigated cranial procedures. A carrier for an electromagnetic DRF was developed, which could be fixed at the posterior edge of the vomer near the center of the head. This nasopharyngeal DRF was compared with a standard DRF fixed to the surface of the forehead. Methods. Image coordinates and real-world coordinates were co-registered and the total target error (TTE) was measured in the frontal and the lateral skull base of formalin fixed human head. At each anatomical site, 10 targets served for TTE determinations and 5 different fiducial combinations were used for registration. Results. With the nasopharyngeal DRF, lower TTE values (2.8 ± 1.4 mm; mean ± SD) were observed when compared with the forehead DRF (3.7 ± 2.8 mm; P = .004). TTEs of both anatomical sites investigated were significantly lower when using the nasopharyngeal DRF (frontal skull base 3.4 vs 2.1 mm, P = .005 and lateral skull base 3.9 vs 3.5 mm, P = .013) than with the standard forehead mounted one. Conclusion. Positioning the DRF in the center of the head significantly improved the application accuracy of targets in the skull base with electromagnetic navigation by 25%. [ABSTRACT FROM PUBLISHER]

Objectives/Hypothesis The differentiated character of changes in the mucous relief of the trachea as induced by air containing pollutants from the wastes of nickel-, mercury-, and cement-producing plants and by Candida albicans occurring in the waste disposal site of a large town are identified. The trachea was chosen because it is the entrance gate for the penetration of polluted air into the lungs. Changes on the trachea influence the character and extent of changes in lungs. Study Design Histological study with Viennese grey strain laboratory rabbits and rats caught directly on an investigated site. Methods We present new results of the functional morphology of the respiratory system as the results of scanning and transmission electron microscopy studies that can reveal character and range of damage of mucosal relief of trachea relevant to the functional dynamics of mucociliary clearance. Under physiological conditions this mechanism allows that only respirable dust particles enter the deep respiratory tract. Results In case of a damaged tracheal relief because of exposure to various aerosols, the functional morphology is changed, which aids in understanding the mechanisms damaging to mucociliary clearance induced by living in heavily polluted areas. Conclusion Understanding of these morphological changes on base of detailed electron microscopic findings sheds new light on elaborating novel diagnostic methods for clinical practice. [ABSTRACT FROM AUTHOR]

Objectives: We demonstrate that computer-assisted frameless stereotactic navigation with the ISG/ELEKTA Viewing Wand system in the petrous bone is routinely possible with sufficient application accuracy. Methods: High-resolution computed tomography imaging is done with a dedicated structure attached to the mouthpiece of the Vogele-Bale-Hohner (VBH) head holder, an integral part of our intraoperative patient fixation. The patient image registration can be reliably performed before surgery in an unsterile environment with the registration structure of the mouthpiece. For intraoperative navigation either the position-sensitive articulated arm or the optical three-dimensional digitizer of the ISG/ELEKTA system is used. Results: In the operations of the petrous bone performed so far, i.e., mastoidectomy, cholesteatoma surgery, and lateral skull base revision surgery, the clinical value of three-dimensional navigation was clearly demonstrated with an application accuracy, constant throughout surgery, mostly limited only by the resolution of the computed tomography. [ABSTRACT FROM AUTHOR]

We report the first intraoperative use of a microdebrider as a stereotactic three-dimensional (3D) navigation instrument in paranasal and frontobasal surgery. The microdebrider uses rotating blades and an integrated suction device for controlled removal of tissue under video-endoscopic view. The ISG Viewing Wand uses the patient's computed tomography/magnetic resonance (CT/MR) data and a 3D reconstruction thereof and a high-precision position-sensitive mechanical arm for intraoperative three-dimensional navigation. We have linked the microdebrider to the Viewing Wand to transform it into a continuously available intraoperative stereotactic localizing device. We discuss the problems related to this extension of the Viewing Wand and demonstrate the practical use in an exemplary polypectomy. [ABSTRACT FROM AUTHOR]

Frameless stereotactic procedures crucially depend on the firmness of immobilization. Once registered, shifting of the patient leads to inaccuracy, and the patient registration has to be realigned. To overcome the drawbacks of conventional invasive fixation for neurosurgery and the widely accepted fixation with surgical tape in ENT, the Vogele-Bale-Hohner (VBH) head holder has been developed. It permits rigid, noninvasive fixation of the head by using an individualized dental cast attached to the upper jaw by vacuum. Oral intubation is uncomplicated. In addition, a special registration device providing well defined reference points can be mounted to the mouthpiece. We report the first promising clinical applications of this device. [ABSTRACT FROM AUTHOR]

We report the intraoperative use of bent probes for 3-dimensional computer-assisted navigation in ENT surgery with the ISG Viewing Wand. Probe calibration is standardized and the new probes comply with the overall application accuracy of the navigation system. The bent probes permit an easy access to the remotest locations of the maxillary and the frontal sinus and are beneficial for application in paranasal sinus surgery. We present our clinical experiences with these probes. [ABSTRACT FROM AUTHOR]

As medical data acquisition has become digital and tomographical scanners allow three-dimensional reconstruction in ease, it is still standard to analyze the data plane by plane or in a multiplanar view. Both are limited to two-dimensional environments and cause difficulties in analyzing complex anatomical and pathological structures. Decreasing hardware prices and PC-clusters, which can compare with more expensive super-computers, will help implementing virtual environments in medicine for teaching, simulation and interacting with medical image data. Using free open source software, such as 3D-Slicer, for segmentation and preparing the data for the CAVE is quick and suitable for clinical use as well as for education. For educational purposes, the use of very high-resolution data sets will be ideal and could be made available for everyone, based on the open source philosophy. [Copyright &y& Elsevier]

In head and neck squamous cell carcinoma (HNSCC) pathologic cervical lymph nodes (LN) remain important negative predictors. Current criteria for LN-classification in contrast-enhanced computed-tomography scans (contrast-CT) are shape-based; contrast-CT imagery allows extraction of additional quantitative data ("features"). The data-driven technique to extract, process, and analyze features from contrast-CTs is termed "radiomics". Extracted features from contrast-CTs at various levels are typically redundant and correlated. Current sets of features for LN-classification are too complex for clinical application. Effective eliminative feature selection (EFS) is a crucial preprocessing step to reduce the complexity of sets identified. We aimed at exploring EFS-algorithms for their potential to identify sets of features, which were as small as feasible and yet retained as much accuracy as possible for LN-classification. In this retrospective cohort-study, which adhered to the STROBE guidelines, in total 252 LNs were classified as "non-pathologic" ( n = 70), "pathologic" ( n = 182) or "pathologic with extracapsular spread" ( n = 52) by two experienced head-and-neck radiologists based on established criteria which served as a reference. The combination of sparse discriminant analysis and genetic optimization retained up to 90% of the classification accuracy with only 10% of the original numbers of features. From a clinical perspective, the selected features appeared plausible and potentially capable of correctly classifying LNs. Both the identified EFS-algorithm and the identified features need further exploration to assess their potential to prospectively classify LNs in HNSCC.

Objectives: In this paper we study effects of irradiation to pulmonary tissue on a micro and ultrastructural level to get insights into the dynamics of morphological changes and associated post-radiative physiological conditions., Methods: Animal and human pulmonary tissue with and without radiation damage was subject to light, transmission, scanning and polarization microscopy and morphometric evaluation., Results: The present investigations on the influence of irradiation on experimental and human lung tissue demonstrate that complex changes are induced in the cells which are essential for mucociliary clearance. These changes are a shortage of alveolar macrophages, cell apoptosis, proliferation of collagen ligament in the barrier of gaseous exchange, retraction of endothelial lining of capillaries and significant broadening of the gaseous exchange barrier, resulting in serious damage for the O2 and CO2 exchange., Conclusions: These changes at microscopic, cellular, and ciliary level trigger conditions for various diseases of the respiratory system, which is further assessed by a simultaneous computer aided estimation of ciliary function. With the concurrent world-wide increase of respiratory diseases, these findings are important knowledge for the clinical practice.

Objectives: To assess factors that affect the accuracy of navigated surgery at the human lateral skull base, including the choice of registration procedures and preoperative computed tomography (CT) section thickness, and to compare target registration error, a measure of clinical application accuracy, with root mean square, an accuracy variable provided by several surgical navigation systems., Design: Experimental cadaver study., Setting: Medical university., Participants: Anatomic specimen., Main Outcome Measures: Target registration error., Results: A combination of high-resolution CT images, 0.5-mm section thickness, with pair-point matching of a combination of markers on the anatomical specimen, and the registration element was found to be superior (mean [SD], 0.72 [0.28] mm). No correlation was found between target registration error and root mean square. A statistical analysis that considers image registration and acquisition method did not show any correlation between target registration error and root mean square error (r = -0.175, P = .15)., Conclusions: High-resolution CT images, 0.5 mm, of the petrous bone and a pair-point registration using loci on the patient and registration superstructures worked best under experimental conditions. Only target registration error was found to provide reliable information on accuracy intraoperatively. In line with the literature, these data prove that root mean square bears little relevance for clinical application accuracy.