Christian Kühnel

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/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 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.

Preclinical imaging has recently been expanded through the use of ostrich embryos as an alternative in vivo model. In ovo experiments represent a promising substitute for conventional rodent-based animal testing. For artifact-free dynamic nuclear medicine imaging, reliable immobilization of embryos is essential. Although previous studies have demonstrated the feasibility of isoflurane anesthesia, the kinetics and uptake mechanisms of isoflurane in ostrich embryos remain insufficiently characterized. The aim of this study was to characterize gas exchange dynamics in ostrich eggs and to quantify isoflurane uptake using two complementary approaches: indirect consumption measurements in a closed system and direct quantification by serial blood sampling. Fourteen ostrich eggs, including seven fertilized and seven unfertilized specimens, were analyzed at developmental stages up to day 37 of incubation. Gas exchange was assessed in a sealed container using a clinical anesthesia gas monitoring system to measure oxygen consumption and carbon dioxide excretion. Isoflurane uptake was evaluated during exposure to concentrations of 2%, 4%, or 6%. In a separate experimental series, serial blood samples were collected during and after exposure to the same concentrations to determine systemic uptake. Fertilized embryos showed progressive increases in metabolic activity, with a maximal oxygen consumption and carbon dioxide excretion of 116 mL/h/kg and 93 mL/h/kg on day 37. Indirect measurements demonstrated isoflurane uptake rates of up to 1.1 mL/min at 6%, with proportionally lower values at 4% and 2%. Blood analyses confirmed systemic absorption, peak concentrations of 160 µg/mL, and detectable residual levels for up to 120 min after exposure. These findings refine in ovo imaging.

Transarterial radioembolization generally results in low radiation exposure for medical staff; ¹⁶⁶ Ho-poly-L-lactic acid microspheres led to the highest body doses, while ⁹⁰ Y-resin microspheres generated the highest hand doses, with interventional radiologists receiving the highest overall doses.

Background/Objectives: The increasing use of radiopharmaceuticals in clinical practice has raised concerns regarding potential radiation exposure for healthcare personnel handling biological samples from treated patients. The objective of this study was to assess the radioactivity levels in clinically necessary blood samples taken from patients treated with radioactive iodine-131 (I-131) or lutetium-177 (Lu-177) in a real-world setting. Methods: Prospective, tertiary care single-center study. Blood samples, at the clinically necessary time points, from 220 consecutive targeted radionuclide therapies (TRTs) used to treat 151 distinct patients between October 2021 and January 2025 were included. The influences of the eGFR and the time interval between tracer administration and blood sampling on radioactivity concentration were investigated by linear regression models. The applied amount of radioactivity was excluded as a confounder by adjusting all cases to 1 GBq. Statistical programming language R was utilized and p < 0.05 was considered significant. Results: The mean age of the patients was 62 years and 52% were male. Mean radioactivity concentrations of 6 vs. 60 kBq/mL were measured at 52 vs. 13 h after application of 1.9 vs. 6.7 GBq I-131 vs. Lu-177, respectively. Better renal function and later blood sampling were both associated with lower radioactivity concentration in blood samples (each p < 0.001). Total radioactivity levels in all samples were well below the upper limits for the disposal of biological samples (1 MBq for I-131 and 10 MBq for Lu-177). Conclusions: There was only a low exposure risk for nuclear medicine personnel and laboratory staff. These findings emphasize that handling blood samples from patients treated with I-131 and Lu-177 in clinical routine is minimal.

Purpose: Primary hyperparathyroidism is one of the most common endocrine disorders and it is only curable by surgery. This study aimed to accurately localize parathyroid adenomas (PTAs) in patients with negative results from conventional diagnostics, consisting of MIBI SPECT/CT and ultrasound, by utilizing F-18-ethylcholine-PET/ultrasound real-time fusion imaging. Fusion ultrasound is a well-established diagnostic tool that enables precise identification and localization of target structures by superimposing MRI, CT, or PET/CT with real-time B-mode ultrasound. The goal was to detect occult PTAs and enable curative targeted parathyroidectomy. Methods: A total of 49 patients with primary hyperparathyroidism were consecutively recruited from routine clinical workflows. Given negative standard diagnostics, patients were referred for FEC-PET/CT followed by FEC-PET/ultrasound. PTAs were categorized as positive, ambiguous, or negative based on FEC-PET/ultrasound findings. A retrospective data analysis was performed, examining PTA volume (ml) based on ultrasound results, SUVmax of PTAs and locoregional lymph nodes, as well as parathyroid hormone, calcium, and phosphate levels. Maximal, minimal, median, mean values, and SDs were reported. Results: Forty-nine PTAs were identified, of which 45 were solitary, whereas 2 patients had double adenomas each. The study showed relatively high rates of ectopic PTAs (28%). No significant differences were observed in FUS-based detection rates between ectopic and orthotopic lesions. PTAs, exhibited significantly higher ( P P <0.05). No significant SUVmax difference was found for lymph nodes in ambiguous cases. FUS-based PTA volume ranged from 0.2 to 2.6 ml (mean 0.5±0.5 ml). Twenty-seven patients underwent surgery, and the diagnosis was confirmed in 90% of cases. Conclusions: This study shows that FEC-PET/ultrasound offers valuable support for preoperative localization and thus can be considered as an effective and precise method for detecting parathyroid adenomas in primary hyperparathyroidism. Because of its high time and technical demands, it is reserved for challenging cases unresolved by standard diagnostics. Future technical advances may increase its accessibility.

Ostrich eggs have recently attracted interest as an alternative model in preclinical nuclear medicine imaging. The ability to be used in clinical PET/CT (positron emission tomography/computed tomography) systems and their ethical profile are advantageous over conventional rodent models and other avian systems. Nevertheless, concerns regarding radiation exposure during repeated CT (computed tomography) imaging of developing embryos remain inadequately addressed. This study aimed to characterize the attenuation impact of eggshells in ostrich eggs and to evaluate the potential for organ-specific dose assessment. A representative ostrich egg was selected from a cohort of 168 eggs and used to construct a dimensionally matched 3D-printed phantom. Organ weights of 83 embryos were documented on development day (DD) 37 to provide a basis for future organ-level dosimetric modeling. Thermoluminescence dosimeters (TLDs) were positioned along the z-axis within both the egg and phantom, and CT dose distributions were measured using a clinical PET/CT system. The mean absorbed dose in the real egg was 16.3 ± 2.0% lower than in the phantom, attributable to radiation attenuation by the 1.89 ± 0.12 mm thick eggshell. CTDI (computed tomography dose index) values remained stable across developmental stages (DD 0–37). Our findings confirm that the ostrich eggshell exerts a significant shielding effect during CT imaging. While ostrich eggs are suitable for serial in-ovo imaging, embryo positioning remains a major limitation for precise dosimetry. Organ weight data enable potential use of AI (artificial intelligence)-based modeling to improve spatial dosimetry accuracy. This study provides essential groundwork for dose optimization and radioprotection in preclinical imaging protocols using ostrich eggs.