Lukas Pillong

Background/Objectives: Parotid ultrasound requires integration of sonographic morphology with clinical context under uncertainty, but conventional agreement and performance metrics provide limited insight into examiner-dependent classification patterns. Building on previously derived examiner-specific surrogate models, we applied a behavioral decision-science framework to examine observable classification patterns and case-level ambiguity. Methods: In this exploratory retrospective single-center secondary analysis, six examiners rated predefined ultrasound image sets from 149 histopathologically verified lesions. Surrogate-tree structure, feature–reference-class associations, signal detection metrics, and case-level ambiguity were analyzed. Internal robustness was assessed using cross-validation and sensitivity analyses. Results: Pruned surrogate trees identified a context-based classification pattern, a morphology-based classification pattern, and a hierarchical morphology-context pattern. Tumor history and lesion boundary were the only retained upper-level classification cues and showed the strongest overall categorical and sonographic associations with the histopathological reference class, respectively. Across 30 cross-validation trees, boundary was the root split in 22 and tumor history in eight; no other root feature occurred. Examiners differed in diagnostic discrimination and estimated decision criterion, with Examiner 3 showing the highest discrimination. Boundary remained the sonographic feature most strongly associated with the histopathological reference class across sensitivity analyses. Descriptor disagreement was associated with decision disagreement and error burden, and four cases showed unanimous but incorrect classifications. Conclusions: In this exploratory retrospective single-center cohort of histopathologically verified lesions, examiner-dependent classification was characterized by observable, model-derived cue structure, feature-use/reference-association alignment, estimated decision-criterion patterns, and case-level ambiguity. These cohort-specific findings do not directly measure examiner cognition and should not be generalized to unselected parotid-ultrasound populations; however, the complementary analyses provide an empirically grounded framework for characterizing observable examiner-dependent classification and identifying testable targets for prospective studies of examiner feedback, descriptor standardization, and decision support.

Background/Objectives: Noninvasive differentiation of parotid gland tumors remains challenging despite ultrasound being the primary imaging modality for salivary gland lesions. Given its examiner dependence, improving diagnostic consistency and transparency is crucial. We quantified interobserver variability in parotid ultrasound, modeled examiner-specific decision patterns using machine learning surrogates, and tested whether surrogate complexity relates to examiner performance. Methods: In this retrospective, single-center study, six examiners independently rated ultrasound images of 149 parotid tumors using predefined descriptors. Performance was summarized using accuracy and the area under the receiver operating characteristic curve (AUC), with 95% confidence intervals (CIs). AUCs were compared using DeLong tests (Holm-adjusted). Interobserver agreement was assessed using pairwise Cohen’s and global Fleiss’ κ. For each examiner, a decision-tree surrogate was trained from structured descriptors and clinical metadata to reproduce examiner labels and visualize decision pathways; performance was estimated by 5-fold cross-validation. Results: Examiner accuracy ranged from 63.5% to 90.5% and AUC from 0.66 to 0.89 (best 0.89, 95% CI 0.83–0.95); the best performer exceeded the two lowest performers (p < 0.001). Agreement was higher for objective descriptors (size: κ = 0.57–0.97) than for subjective descriptors (echogenicity: κ = 0.11–0.79). Surrogate decision-tree accuracy versus histopathology ranged from 57.2% to 80.0% for unpruned and from 65.1% to 76.5% for pruned models, with high coverage (95.3–98.7%). Tree complexity showed no consistent association with examiner performance. Conclusions: Parotid ultrasound shows substantial interobserver variability. Interpretable surrogates can approximate individual labeling behavior from structured descriptors and clinical metadata, making examiner-dependent decision patterns explicit.

Background: Digitalisation is transforming medical education, but its integration into ultrasound training remains limited. This study evaluates the needs of students and physicians regarding digitally supported ultrasound education. Materials and Methods: A multi-year cross-sectional study (2017–2022) employed two standardised questionnaires. The first assessed the perceived relevance of ultrasound in medical education, the desirability of compulsory teaching, and the integration of digital media and case-based learning. The second explored user-centred requirements for e-learning formats, including functionality, multimedia design, usability, interactivity, and financing, as well as current use of digital devices and reference materials. Data were collected using dichotomous and 7-point Likert scales (1 = high need/strong agreement, 7 = low need/weak agreement). Results: A total of 3479 responses were analysed (2821 students; 658 physicians). Both groups showed strong support for integrating ultrasound into curricula (1.3 ± 0.7) and mandatory education (1.4 ± 0.9), with students expressing significantly greater support (p < 0.001). There was broad agreement on the integration and development of digital media (1.7 ± 1.0), as well as the use of case studies (1.4 ± 0.8), with no significant differences between groups (p > 0.05). Case-based learning as a stand-alone format was less favoured (3.4 ± 1.9). In the user-centred needs analysis, both groups rated features like search functions (1.4 ± 0.8), usability (1.5 ± 0.9), and learning objective checks (2.7 ± 1.6) as important. High-quality media (1.5 ± 0.9) and pathology explanations (1.6 ± 1.1) were also highly valued. Students primarily relied on digital platforms, while physicians used a more varied mix of digital platforms, guidelines, and textbooks. Conclusions: The study highlights the need for more extensive, digitally supported ultrasound training, with a focus on functionality and usability. Standardisation through structured certification processes should be considered for future implementation.

Background: The definite diagnosis of Parkinson’s disease (PD) is usually made by the detection of α-synuclein aggregates in the brain post mortem with the rare exception of some genetic forms. Traces of α-synuclein aggregates in extracerebral tissue biopsies may serve as an appropriate biomarker to confirm a clinical diagnosis in vivo . Objectives: We set out to determine whether the detection of α-synuclein aggregates in submandibular gland biopsies is an effective means for diagnosing PD patients. Methods: We examined submandibular gland biopsies from 25 patients with PD under investigation and 25 age-matched controls to detect α-synuclein aggregates using real-time quaking induced conversion (RT-QuIC) as a seed amplification-assay and immunohistochemical α-synuclein aggregate detection and paraffin-embedded tissue blot (PET-blot) as confirmatory methods. Results: Our RT-QuIC assay detected α-synuclein aggregates in submandibular gland biopsies with a sensitivity of 81,1%, which increased to 90% after a clinical follow-up, and a specificity of 100%. The PET-blot with mAb5C12 confirmed 50% of the RT-QuIC positives and offered a sensitivity of 45,8% (50% after clinical follow-up) and a specificity of 100%. Immunohistochemical detection using the same antibody confirmed 28% of the RT-QuIC positives, but found two of the controls to be positive and therefore provided a sensitivity of 26,1% (28,6% after clinical follow-up) and a specificity of 92%. Conclusions: The RT-QuIC Assay demonstrated comparable sensitivity to the clinical diagnosis (when neuropathologic examination represents the gold standard) and exhibited a similar level of specificity as the PET-blot.

Purpose: Juvenile angiofibroma (JA) is a rare, benign fibrovascular tumor that predominantly affects adolescent males. The underlying biological mechanisms remain poorly understood. Fibroblast activation protein (FAP), known for its involvement in tumor invasion, matrix remodeling, and angiogenesis, has been implicated in various malignancies but has not been studied in JA so far. Methods: We investigated FAP expression in JA samples ( N = 19) using real-time (RT)-PCR ( N = 10) and immunohistochemistry ( N = 18). In addition, Vimentin and PECAM1/CD31 were analyzed to further characterize the tumor microenvironment. For one patient, preoperative FAPI-PET/CT imaging was conducted, and FAP expression was correlated with radiotracer uptake. Postoperative histopathological analyses of the excised tumor were performed to validate the imaging findings. Results: We found consistent expression of FAP, Vimentin and PECAM1/CD31 in all JA analyzed by RT-PCR. Moreover, substantial intra-and intertumor heterogeneity in FAP protein expression was observed, ranging from negative up to strong positive areas. Vimentin and PECAM1/CD31 showed variable expression patterns consistent with the fibrovascular character of JA. FAPI-PET/CT imaging accurately identified the tumor, with radiotracer uptake closely matching the distribution of FAP expression observed histologically. Conclusions: This study is the first demonstrating FAP expression in JA and validating its occurrence using FAPI-PET/CT imaging. The strong correlation between FAP expression and radiotracer uptake in FAPI-PET/CT highlights the potential of this imaging modality as a non-invasive diagnostic tool. This will improve diagnosis and is the basis for further investigations of FAP-targeted therapies for JA treatment.

Background: Simulator-based training (SBT) transforms medical education from traditional methods to technology-driven simulations for safer, complex scenario learning. This study examines perceptions, benefits, drawbacks, and challenges of such training, focusing on ultrasound simulations among medical students and physicians. Methods: The study surveyed 343 participants: 154 third-year medical students, 97 practical-year students, and 92 physicians across various specialties. A digital questionnaire was used to analyze their views on SBT, featuring main- and sub-items evaluated through a Likert scale and dichotomous questions. Results: Widespread exposure to SBT was evident, notably in ultrasound simulator usage, where over 60% of all respondent groups reported prior experience. Significant disparities in acceptance and assessment between students and physicians were noted, particularly highlighting inconsistent integration into mandatory education and a marked deficit in physicians’ training (p < 0.001). All groups acknowledged the relevance of SBT for developing practical skills and patient safety. The interest in ultrasound simulator use showed variability across specialties (p < 0.001). While ultrasound pathology training was highly valued, doubts about simulators replacing hands-on patient experience persisted. Conclusions: Our study highlights the necessity for enhanced integration of SBT within medical curricula. It highlights the significance of adaptive teaching methodologies and singles out ultrasound simulator training as essential for practical skill development. Future research should concentrate on creating comprehensive customized teaching strategies to elevate the quality of patient care.

Background: Nodular fasciitis is a benign, singularly occurring nodular fibroblastic/myofibroblastic neoplasia. Due to the rapid growth and cellular atypia, this rare differential diagnosis in the head and neck region can be mistaken for malignant sarcomas. Methods: We present a 40-year-old female patient with an unclear, rough, and poorly displaceable supraclavicular swelling on the right as part of a medical check-up. Sonographically, the lump was poorly circumscribed with little vascularization. A consecutive core needle biopsy of the lesion yielded inconclusive results showing spindle-shaped tumor cells. ⁶⁸Ga-FAPI-PET/CT showed an intensive uptake of the right supraclavicular lesion in addition to postoperative changes in the right tonsil. Subsequent operative partial excision of the lesion confirmed the histopathological diagnosis of nodular fasciitis. Results: Nodular fasciitis is the most prevalent pseudosarcoma found in soft tissues. This case is the first description of ⁶⁸Ga-FAPI-PET/CT in nodular fasciitis. Surgical removal is advised; nevertheless, the tumor frequently diminishes on its own, and recurrence is rare. Extensive surgical therapy is not necessary. Conlcusions: The recognition of nodular fasciitis and its benign characteristics is crucial to prevent diagnostic errors and the subsequent unnecessary operative treatment of the patient.

Juvenile angiofibroma (JA) is a rare, sex-specific, and highly vascularized nasal tumor that almost exclusively affects male adolescents, but its etiology has been controversial. The G protein-coupled hormone receptor LHCGR [luteinizing hormone (LH)/choriogonadotropin (hCG) receptor] represents a promising new candidate for elucidating the underlying mechanisms of sex specificity, pubertal manifestation, and JA progression. We used highly sensitive RNAscope technology, together with immunohistochemistry, to investigate the cellular expression, localization, and distribution of LHCGR in tissue samples from JA patients. Our results provide evidence for LHCGR expression in subsets of cells throughout JA tissue sections, with the majority of LHCGR⁺ cells located in close vicinity to blood vessels, rendering them susceptible to endocrine LH/hCG signaling, but LHCGR⁺ cells were also detected in fibrocollagenous stroma. A majority of LHCGR⁺ cells located near the vascular lumen co-expressed the neural crest stem cell marker CD271. These results are intriguing as both LH and hCG are produced in a time- and sex-dependent manner, and are known to be capable of inducing cell proliferation and angiogenesis. Our results give rise to a new model that suggests endocrine mechanisms involving LHCGR and its ligands, together with autocrine and paracrine signaling, in JA vascularization and cell proliferation.

The acquisition of ultrasound skills is an essential part of any medical student’s education. University access restrictions in the context of the COVID-19 pandemic have highlighted the need for digitization in teaching. However, teaching manual skills in online courses has proven to be challenging, not least in terms of human resources. Therefore, the aim of this study was to set up a hybrid head and neck ultrasound course consisting of a preface of video-based self-study followed by supportive instruction by a tutor in telepresence and to evaluate the quality, effectiveness, and feasibility of this teaching method. Thirty-five students were shown video tutorials on systematic ultrasound of the neck course. Learning outcomes were analyzed using self-assessment questionnaires and external assessment by an experienced ultrasonographer. All participants demonstrated statistically significant learning improvement (p < 0.001) when comparing self-assessment scores before and after training. The mean self-assessment scores increased from 13.8 to 26.6 for the telepresence-guided group, from 16.6 to 27.3 for the web-based group, and from 14.0 to 26.2 for the in-person group. The external observer assessment also showed improvement, with mean scores of 46.7, 48.1, and 46.5, respectively. Overall results did not significantly differ when comparing different instruction modalities. A telepresence-guided video-based ultrasound course is well suited to teaching ultrasound skills similar to in-person courses and allows a more resource-efficient targeting of student needs.