Martin Freesmeyer

Background: Accurate thyroid volume determination is essential for treatment planning. This feasibility study evaluated the accuracy of a novel tomographic ultrasound (tUS) approach compared to 2D ultrasound, using contrast-enhanced computed tomography (ceCT) as reference standard. Methods: In this prospective, single-center study, 50 patients undergoing neck ceCT were enrolled. Thyroid volume was measured by 2D ultrasound (ellipsoid model), automatedvolume (tUS uncorrected), physician-corrected volume (tUS corrected) and ceCT. Linear regression for proportional bias, log-transformed Bland–Altman analysis, clinical error metrics and correction duration were evaluated. Results: 2D ultrasound showed significant proportional bias (slope=-0.215, p<0.0001) and systematic underestimation (mean difference -6.0mL; geometric mean ratio 0.76). Corrected tUS eliminated proportional bias (p=0.0557) and reduced bias (mean difference +0.8mL; geometric mean ratio 1.04). Corrected tUS achieved lower MAE (4.42mL vs. 6.53mL) and MAPE (19.4% vs. 25.4%) than 2D ultrasound, placing 60.0% vs. 34.0% of cases within ±20% error limits. In enlarged glands (n=19), corrected tUS maintained superior accuracy (MAE 5.82mL, MAPE 12.4%) versus 2D ultrasound (MAE 11.35mL, MAPE 26.5%). Physician correction averaged 2:51minutes, independent of thyroid volume (r=-0.081, p=0.5784). Conclusions: In this feasibility study, physician-corrected tUS reduced the size-dependent systematic underestimation observed with 2D ultrasound and yielded volumes closer to ceCT, particularly in enlarged glands, within a clinically feasible workflow. Because the best-performing method required manual expert correction and the limits of agreement with ceCT exceeded the predefined clinical threshold, corrected tUS should be regarded as a promising semi-automated approach that requires further validation, including interobserver assessment, before it can be considered interchangeable with ceCT.

Background: PSMA PET/CT plays an important role in biochemically recurrent prostate cancer (BCR-PCa). In general, PET/CT is performed as a limited or true whole-body examination. The majority of PET/CT scanners operate by measuring several bed positions or continuous motion with a limited axial field of view (FOV). Shortening the scan area thus results in a time saving, with unknown information loss regarding the detection of tumor manifestations. Methodology: This retrospective single-center study included 200 patients with BCR-PCa after initial curative therapy who underwent a ⁶⁸ Ga-PSMA-PET/CT scan from vertex to toe (true whole-body). Using retrospective subdivision into hypothetical partial body measurement protocols, the undetected tumor manifestations were examined. Classic PET/CT protocols were used: vertex to mid-thigh, skull base to mid-thigh, as well as CT-equivalent examination areas: chest/abdomen/pelvis (CAP), abdomen/pelvis (AP) and pelvis. Results: Of 200 patients with a median PSA of 1.1 ng/mL, 128 (64%) showed at least one structural correlate of BCR-PCa in the true whole-body scan. The overall detection rate did not change for limited classic PET-protocols, or CAP measurements. CAP scans would not have detected all tumor manifestations in 16 patients (8%) and not all tumor-affected organ systems in six patients (3%), AP scans in 41 patients (21%) and 18 patients (9%), pelvic scans in 61 patients (31%) and 37 patients (19%), respectively. PSA may contribute to the prospective restriction of the scan area. Patients with PSA ≤ 0.75 ng/mL showed no diagnostic gain from whole-body imaging. This means that in 45% of patients in our cohort, a limitation to CAP scan would have been possible without losing information. Conclusions: For a resource-saving use of routine PSMA-PET/CT, a scan from the vertex to the mid-thigh seems sufficient for detecting relevant metastases. For patients with low PSA levels, a more focused protocol that includes only the CAP region can be considered.

Background/Objectives: To assess the agreement between an artificial intelligence (AI)-based decision support system (DS System), applied in real time directly on the ultrasound console, and an expert panel for ACR TI-RADS classification of thyroid nodules (TNs) in a region with a history of iodine deficiency and a consequently high prevalence of TNs. Methods: A single-center prospective study including 118 consecutive patients (with 276 TNs) referred for thyroid ultrasound between March and May 2024. DS System ultrasound features, ACR TI-RADS classifications (TR1–TR5) and management recommendations were recorded per TN, with and without the ‘AI-Adapter’ (AI-based modification of the TI-RADS score), and compared to the consensus assessment of a TI-RADS expert panel (paired tests of marginal homogeneity, Cohen’s unweighted and weighted κ; all analyses adjusted for clustering of TNs within patients). Results: No malignancy was identified during 24-month follow-up (composite reference standard; cytology or histology in six TNs). The DS System could be applied to all TNs without technical failure. Marginal distributions differed between the expert panel and the DS System for all ultrasound feature categories except echogenicity (p = 0.23). Interrater agreement ranged from poor (“lobulated or irregular”, κ = −0.08) to substantial (“cystic or almost completely cystic”, κ = 0.62), most frequently slight to fair. TI-RADS classifications showed slight agreement with (κ = 0.04; linear-weighted κ = 0.14) and without AI-Adapter (κ = 0.13; linear-weighted κ = 0.21). The AI-Adapter changed the ACR TI-RADS score by −1.01 ± 1.04 points. Management recommendations showed fair agreement with (κ = 0.23) and without the AI-Adapter (κ = 0.39). Although the number of TR5 ratings was similar (expert panel: 27; DS System: 26 without and 30 with the AI-Adapter), only seven and eight of the 27 TR5 TNs of the expert panel, respectively, were also rated TR5 by the DS System. Conclusions: Real-time application of the DS System on the ultrasound console was technically feasible, but agreement with an expert panel was low. As all TNs were benign, diagnostic accuracy and clinical safety could not be assessed. Validation in cohorts including malignant TNs is required before the DS System can be considered a substitute for expert assessment in regions with a high prevalence of TNs.

Conventional ultrasound phantoms typically lack anatomical surface geometry and procedural access constraints, limiting the transferability of acquired skills to clinical practice. The objective of the present work was to develop and describe such a platform for ultrasound-guided thyroid nodule puncture training, including its construction and initial ultrasound appearance. We present a modular, body-mimicking ultrasound phantom platform comprising three components: an anatomically shaped epoxy composite chassis cast from a healthy volunteer and covering the cervical and upper thoracic region, interchangeable gelatin-based inserts representing thyroid (including puncture target lesions) and surrounding tissue structures, and an integrated dual-camera optical feedback system for real-time and post-procedural needle trajectory visualization. Two chassis configurations reflecting different chin and shoulder positions allow deliberate modulation of procedural difficulty. Insert composition can be varied to simulate tissues of differing echogenicity and density, including liquid-filled targets. Under appropriate storage and disinfection conditions, inserts remained usable for up to four weeks in qualitative observation. The optical feedback system supports self-directed learning and structured debriefing. In combination with magnet-based ultrasound needle guidance technology, the platform is intended to support a longitudinal, competency-based training concept with quantifiable performance metrics, enabling systematic documentation of individual learning curves. The presented system is designed to more closely replicate the anatomical and procedural complexity of clinical ultrasound-guided interventions than conventional phantoms and represents a flexible simulation platform for interventional ultrasound education.

A 64-year-old woman presented with recurrent abdominal pain and rapid weight loss of 10 kg. Five years prior, an abdominal endovascular aneurysm repair (EVAR) was performed, followed by an open repair with proximal graft interposition due to an endoleak type IA two years ago. Laboratory tests revealed only moderately elevated infection markers (CrP 66 mg/L, WBC 14 GPt/L). ¹⁸F-FDG PET/CT showed a hypermetabolic peri-aortic mass initially suspected to be inflammatory. However, the patient did not exhibit signs of fever. Because of the equivocal constellation, a fine-needle biopsy was conducted, revealing malignant cells. The patient underwent complete tumor resection including aortic replacement. Histopathology confirmed the diagnosis of an angiosarcoma. The treatment was then supplemented with chemotherapy using doxorubicin and ifosfamide.

Purpose: To evaluate the clinical feasibility and potential utility of dynamic [ ⁶⁸ Ga]Ga-TEoS-DAZA PET/CT for the detection and localisation of bile leaks in patients after hepatobiliary surgery in a small, single-centre feasibility series. Methods: Ten patients with clinically suspected postoperative bile leakage and prior inconclusive imaging underwent [ ⁶⁸ Ga]Ga-TEoS-DAZA PET/CT between September 2024 and February 2026. Imaging was performed following intravenous administration of [ ⁶⁸ Ga]Ga-TEoS-DAZA (mean activity 214 ± 27 MBq). Dynamic PET acquisition was conducted for 60 min. Findings were analysed and classified according to the Nagano system where applicable, and their contribution to subsequent clinical management was assessed. Results: [ ⁶⁸ Ga]Ga-TEoS-DAZA PET/CT enabled localisation of bile leaks in 9 of 10 patients (90%). Leak sites were diverse including central and peripheral locations, as well as complex locations, such as ducts of Luschka and bilioenteric anastomoses. Mean detection time was 28.7 min post injection. PET/CT findings informed subsequent clinical management in all patients, including endoscopic, percutaneous, surgical interventions, or continued drainage management. No adverse effects were observed. Conclusion: Dynamic [ ⁶⁸ Ga]Ga-TEoS-DAZA PET/CT was feasible for bile leak localisation in this selected cohort, including complex and peripheral leak sites. Its physiological, antegrade imaging approach provided clinically useful information in patients with inconclusive or unsuccessful conventional imaging. Further prospective comparative studies are warranted to validate these findings and evaluate its diagnostic performance in larger cohorts.

The rapid adoption of asynchronous e-learning during the COVID-19 pandemic has raised questions regarding the sustainability of student engagement in digital teaching formats over time. The objective of this study was to examine the trends in participation over time in a mandatory asynchronous course within the domain of preclinical medical education. A longitudinal observational design was applied across multiple cohorts from summer term 2020 to winter term 2025/2026. The course structure, consisting of a video based learning module, a mandatory quiz for participation validation, and an optional synchronous consultation, remained unchanged throughout the study period. Participation, quiz completion, performance, and consultation attendance were assessed descriptively. A total of 703 students participated, of whom 628 completed the quiz. The number of participants per course ranged from 5 to 85, while the number of eligible students ranged from 398 to 745. Quiz completion among participants remained consistently high across all cohorts. Mean quiz scores ranged from 7.20 to 10.00 points. Participation in optional synchronous consultation ranged from 0 to 7 students. Over time, participation decreased, whereas quiz completion and performance among participating students remained stable. These findings indicate that temporal changes primarily affected initial engagement rather than learning outcomes among active participants, highlighting the importance of distinguishing between participation and performance when evaluating asynchronous digital teaching formats.

Animal models are utilized in the investigation of a variety of research questions in nuclear medicine. Radiopharmaceutics are usually tested in mouse, rat or chick chorioallantoic membrane (CAM) models and visualisation of their biodistribution is performed using dedicated small-animal PET/CT scanners. However, the limited availability of such scanners represents a significant bottleneck in preclinical imaging. To address this limitation, we explored an alternative animal model compatible with clinical imaging systems. The ostrich chorioallantoic membrane (CAM) was utilized as a platform for tumor xenografts, enabling imaging with a standard human PET/CT scanner. Growth conditions for tumor formation were established using human glioblastoma (U87) and breast cancer (MDA-MB-231) cell lines. Tumor visualization was achieved using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG), a widely used clinical PET tracer, and its pharmacodynamic behavior was assessed. Our findings demonstrate that the ostrich CAM tumor model is a feasible and efficient system for the rapid evaluation of diagnostic tracers. Importantly, tracer uptake and kinetics can be reliably assessed using a clinical PET/CT scanner. This approach highlights the potential of the ostrich embryonic model as a versatile and accessible preclinical platform for nuclear medicine research.

A 74-year-old woman with a history of non-small cell lung cancer underwent 18F-FDG PET/CT to rule out recurrence of the disease. The whole-body scan revealed a nodule in the left upper lobe of the lung that could not be unequivocally distinguished as either malignant or inflammatory. A segmental minimal activity (MA) PET/CT was performed for clarification, as it offers additional metabolic information without significantly increasing radiation exposure. Based on the MA-PET/CT scan and clinical findings, the nodule was classified as inflammatory. To the best of our knowledge, the use of MA-PET/CT in cases of suspected lung cancer recurrence has rarely been reported so far.