Eric Einspänner

Objective: In patients with non-lesional epilepsy, MR imaging detects no structural or functional abnormalities. The aim of this study was to determine whether subtle local reductions or increases in brain volume, undetectable to the human eye, can indicate an epileptic focus directly or indirectly. To address this, we performed brain volumetry using 7T MRI. Methods: We evaluated 7T MRI in patients with non-lesional epilepsy as part of a retrospective study and a healthy control cohort from another prospective study. FastSurfer segmentations were performed using T1 MPRAGE. Additionally, we also performed volumetry of the hippocampal subfields, the thalamic nuclei and the brainstem. We created a control group matched for age and gender distribution. Results: 7T segmentation as described above was possible in 14 patients with epilepsy and 27 participants of a control cohort. We detected a significant volume loss in the ipsilateral central lateral nucleus of thalamus, as well as a significant increase in the presubiculum body and the ipsilateral and contralateral entorhinal and medial orbitofrontal cortices. Conclusion: High-resolution 7T MRI-based volumetric analysis in patients with non-lesional epilepsy revealed significant atrophy in brain regions commonly implicated in epileptogenesis. These structures exhibited strong sensitivity and specificity, highlighting the potential of volumetry as a diagnostic tool in the absence of visible lesions. Validation in larger, independent cohorts is required to confirm these findings and assess clinical applicability.

Objectives: This study evaluated 3 LLM chatbots (GPT-3.5-turbo, GPT-4-turbo, and GPT-4o) on their effectiveness in supporting patient education by answering common patient questions for CT, MRI, and DSA informed consent, assessing their accuracy and clarity. Methods: Two radiologists formulated 90 questions categorized as general, clinical, or technical. Each LLM answered every question 5×. Radiologists then rated the responses for medical accuracy and clarity, while medical physicists assessed technical accuracy using a Likert scale. Semantic similarity was analyzed with SBERT and cosine similarity. Results: Ratings improved with newer model versions. Linear mixed-effects models revealed that GPT-4 models were rated significantly higher than GPT-3.5 (P < .001) by both physicians and physicists. However, physicians’ ratings for GPT-4 models showed a significant performance decrease for complex modalities like DSA and MRI (P < .01), a pattern not observed in physicists’ ratings. SBERT analysis revealed high internal consistency across all models. SBERT analysis revealed high internal consistency across all models. Conclusion: Variability in ratings revealed that while models effectively handled general and technical questions, they struggled with contextually complex medical inquiries requiring personalized responses and nuanced understanding. Statistical analysis confirms that while newer models are superior, their performance is modality-dependent and perceived differently by clinical and technical experts. Advances in knowledge: This study evaluates the potential of LLMs to enhance informed consent in radiology, highlighting strengths in general and technical questions while noting limitations with complex clinical inquiries, with performance varying significantly by model type and imaging modality.

Purpose: High-resolution multislice CT (HR-MSCT) and cone beam CT (CBCT) are commonly used for preoperative temporal bone imaging, with HR-MSCT often preferred due to its shorter scan duration and lower susceptibility to motion artifacts. However, recent advancements in accelerated flat panel CT (Acc-FPCT) available with the latest generation angiography systems have addressed traditional limitations of CBCT by significantly decreasing scan time. This cadaver-based study evaluates the diagnostic performance and radiation dose of Acc-FPCT compared to HR-MSCT in preoperative temporal bone imaging. Methods: Six different Acc-FPCT protocols were acquired on five whole-head cadaveric specimens (ten temporal bones). Three neuroradiologists experienced in temporal bone imaging assessed the image quality of Acc-FPCT protocols in comparison to that of HR-MSCT for the visualization of 31 landmarks of middle and inner ear using a 5-point Likert scale. We also compared radiation dose parameters (CT dose index and dose length product) among the protocols. Results: Two high-Resolution Acc-FPCT protocols were found to be superior to HR-MSCT by all raters (p < 0.001). There were no significant differences between the two HR-FPCT protocols (p = 0.25). The remaining Acc-FPCT protocols were rated significantly inferior to HR-MSCT. The inter-rater reliability was excellent (ICC (2,k) = 0.925; CI [0.92–0.93]). The dose length product was significantly lower in all Acc-FPCT protocols compared to HR-MSCT. Conclusion: The results of our cadaver-based study highlight the utility of certain Acc-FPCT protocols as a viable alternative to HR-MSCT in preoperative temporal bone imaging, improving the visualization of critical anatomical landmarks without increasing radiation exposure.

Background: Due to comparatively long measurement times in simultaneous positron emission tomography and magnetic resonance (PET/MR) imaging, patient movement during the measurement can be challenging. This leads to artifacts which have a negative impact on the visual assessment and quantitative validity of the image data and, in the worst case, can lead to misinterpretations. Simultaneous PET/MR systems allow the MR-based registration of movements and enable correction of the PET data. To assess the effectiveness of motion correction methods, it is necessary to carry out measurements on phantoms that are moved in a reproducible way. This study explores the possibility of using such a phantom-based setup to evaluate motion correction strategies in PET/MR of the human head. Method: An MR-compatible robotic system was used to generate rigid movements of a head-like phantom. Different tools, either from the manufacturer or open-source software, were used to estimate and correct for motion based on the PET data itself (SIRF with SPM and NiftyReg) and MR data acquired simultaneously (e.g. MCLFIRT, BrainCompass). Different motion estimates were compared using data acquired during robot-induced motion. The effectiveness of motion correction of PET data was evaluated by determining the segmented volume of an activity-filled flask inside the phantom. In addition, the segmented volume was used to determine the centre-of-mass and the change in maximum activity concentration. Results: The results showed a volume increase between 2.7 and 36.3% could be induced by the experimental setup depending on the motion pattern. Both, BrainCompass and MCFLIRT, produced corrected PET images, by reducing the volume increase to 0.7–4.7% (BrainCompass) and to -2.8–0.4% (MCFLIRT). The same was observed for example for the centre-of-mass, where the results show that MCFLIRT (0.2–0.6 mm after motion correction) had a smaller deviation from the reference position than BrainCompass (0.5–1.8 mm) for all displacements. Conclusions: The experimental setup is suitable for the reproducible generation of movement patterns. Using open-source software for motion correction is a viable alternative to the vendor-provided motion-correction software.

Ziel/Aim Aufgrund vergleichsweise langer Messzeiten bei der PET/MRT-Bildgebung sind Bewegungen der Patienten während der Untersuchung wahrscheinlich. Diese führen zu Artefakten, welche sich negativ auf die visuelle Beurteilbarkeit und quantitative Validität der Bilddaten auswirken und im ungünstigsten Fall zu Fehleinschätzungen führen. Simultane PET/MRT-Systeme erlauben eine Registrierung der Bewegungen und ermöglichen eine Korrektur der PET-Daten. Ziel dieser Arbeit ist es, zwei bestehende Bewegungskorrekturverfahren (BKV), den herstellereigenen BrainCompass (BC, Siemens Healthineers AG) und die open-source Software FSL-MCFLIRT (1), zu evaluieren. Methodik/Methods Um die Effektivität der BKV zu beurteilen, ist es notwendig, Messungen an Phantomen, welche reproduzierbar bewegt werden, durchzuführen. Als Phantom diente eine realitätsnahe Schädelnachbildung (2) mit eingelagerter Läsion (Kolben, 50 ml). Für gezielte Bewegungen wurde eine Versuchsvorrichtung entwickelt. Ein MR-kompatibles Robotersystem (Innomotion by Innomedic) diente der Erzeugung rigider Bewegungen und Quantifizierung der BKV. Neben reinen Translationsbewegungen (0 bis 20,24 mm) konnten Rotationsbewegungen (0 bis 5,98°) und komplexere Bewegungsmuster erzeugt und evaluiert werden. Ergebnisse/Results Die Ergebnisse zeigen, dass durch den Versuchsaufbau eine Volumenzunahme von 2,65 bis 33,8 % induziert werden konnte. Der BC vermindert die Zunahme auf 0,73 bis 6 %, FSL-MCFLIRT auf 0,05 bis 1,97 %. Schlussfolgerungen/Conclusions Der Versuchsaufbau eignet sich für eine reproduzierbare Erzeugung von Bewegungsmustern. Dies ermöglichte eine Evaluierung rigider BKV. Neben der lizensierten Software von Siemens stellt die open-source Variante eine sehr gute Alternative dar.