Publications by authors named "Johann Martin Hempel"

(1) Background: to test the diagnostic performance of a fully convolutional neural network-based software prototype for clot detection in intracranial arteries using non-enhanced computed tomography (NECT) imaging data. (2) Methods: we retrospectively identified 85 patients with stroke imaging and one intracranial vessel occlusion. An automated clot detection prototype computed clot location, clot length, and clot volume in NECT scans.

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Cerebral hypoperfusion and vascular dysfunction are closely related to common risk factors for ischemic stroke such as hypertension, dyslipidemia, diabetes, and smoking. The role of inhibitory G protein-dependent receptor (GPCR) signaling in regulating cerebrovascular functions remains largely elusive. We examined the importance of GPCR signaling in cerebral blood flow (CBF) and its stability after sudden interruption using various in vivo high-resolution magnetic resonance imaging techniques.

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Human stapedius muscle (SM) can be directly and safely accessed via retrofacial approach, opening new approaches to directly measure the electrically evoked stapedius reflex threshold (eSRT). The measurement of the SM activity via direct surgical access represents a potential tool for objective eSRT fitting of cochlear implants (CI), increasing the benefit experienced by the CI users and leading to new perspectives in the development of smart implantable neurostimulators. 3D middle-ear reconstructions created after manual segmentation and related SM accessibility metrics were evaluated before the CI surgery for 16 candidates with assessed stapedius reflex.

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As a result of technical developments and greater availability of imaging equipment, the number of neuroradiological examinations is steadily increasing [1]. Due to improved image quality and sensitivity, more details can be detected making reporting more complex and time-intensive. At the same time, reliable algorithms increasingly allow quantitative image analysis that should be integrated in reports in a standardized manner.

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Background: Complicated nonstenosing carotid artery plaques (CAPs) are an under-recognized cause of stroke.

Objectives: The purpose of this study was to determine whether complicated CAP ipsilateral to acute ischemic anterior circulation stroke (icCAP) are associated with recurrent ischemic stroke or transient ischemic attack (TIA).

Methods: The CAPIAS (Carotid Plaque Imaging in Acute Stroke) multicenter study prospectively recruited patients with ischemic stroke restricted to the territory of a single carotid artery.

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Background: Validation of the 2016 RANO MRI scorecard for leptomeningeal metastasis failed for multiple reasons. Accordingly, this joint EORTC Brain Tumor Group and RANO effort sought to prospectively validate a revised MRI scorecard for response assessment in leptomeningeal metastasis.

Methods: Coded paired cerebrospinal MRI of 20 patients with leptomeningeal metastases from solid cancers at baseline and follow-up after treatment and instructions for assessment were provided via the EORTC imaging platform.

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is a typical mold causing cerebral abscesses, often after near-drowning. Infections are associated with high morbidity and mortality due to diagnostic challenges including the need for prolonged incubation of cultures. In addition, histopathological differentiation from other filamentous fungi, including may not be possible, excluding early specific diagnosis and targeted therapy.

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Introduction: Meningiomas are the most common benign intracranial neoplasms. CNS invasion in meningiomas has been integrated into the 2016 WHO classification of CNS tumors as a stand-alone criterion for atypia. Since then, its prognostic impact has been debated based on contradictory results from retrospective analyses.

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Background: There are a multitude of application possibilities of artificial intelligence (AI) and structured reporting (SR) in radiology. The number of scientific publications have continuously increased for many years. There is an extensive portfolio of available AI algorithms for, e.

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The expression of somatostatin receptors in meningioma is well established. First, suggestions of a prognostic impact of SSTRs in meningioma have been made. However, the knowledge is based on few investigations in small cohorts.

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Article Synopsis
  • The study aimed to assess radiological findings on temporal bone CT scans linked to obstructive Eustachian tube dysfunction, testing its effectiveness for diagnosis.
  • It involved 40 patients over 16 with unilateral Eustachian tube dysfunction, using a Valsalva maneuver to improve imaging quality, and analyzed various structural changes and the presence of mucus.
  • Results showed that while mucus was significantly linked to dysfunction, the overall diagnostic sensitivity was low (52.5%), indicating CT is not a suitable routine screening tool for this condition.
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Purpose: To investigate the diagnostic performance of in vivo ADC-based stratification of integrated molecular glioma grades.

Materials And Methods: Ninety-seven patients with histopathologically confirmed glioma were evaluated retrospectively. All patients underwent pre-interventional MRI-examination including diffusion-weighted imaging (DWI) with implemented b-values of 500, 1000, 1500, 2000, and 2500 s/mm.

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Background: Injury to the artery of Adamkiewicz (AKA) during surgery may lead to spinal cord ischemia and severe neurologic complications. Posterior mediastinal tumors may be adjacent to AKA, but data on preoperative visualization of AKA in children are rare. This study analyzed the importance of identifying the AKA preoperatively by spinal digital subtraction angiography (DSA) in children with posterior mediastinal tumors for therapeutic procedure.

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Purpose:  Structured reporting is an essential step in establishing standardized quality standards in diagnostic radiology. The German Society of Radiology and the German Society of Neuroradiology aim to provide templates for the structured reporting of different radiological examinations.

Method:  The Information Technology working group of the German Society of Radiology developed structured templates for the radiological reporting of different indications in consensus with specialist support by experts.

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It is believed that stroke occurring due to posterior circulation large vessel occlusion (PCLVO) and that occurring due to anterior circulation large vessel occlusion (ACLVO) differ in terms of their pathophysiology and the outcome of their acute management in relation to endovascular mechanical thrombectomy (MT). Limited sample size and few randomized controlled trials (RCTs) with respect to PCLVO make the safety and efficacy of MT, which has been confirmed in ACLVO, difficult to assess in the posterior circulation. We therefore conducted a meta-analysis to study to which extent MT in PCLVO differs from ACLVO.

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Article Synopsis
  • - Most meningiomas are slow-growing tumors from arachnoid cap cells, typically treatable through surgery or radiation, but aggressive cases often recur and lack established alternative treatments.
  • - Identifying the risk of recurrence is crucial, with several clinical and molecular markers being used, while the invasive growth of tumor cells into CNS tissue is linked to higher recurrence rates and was included in the WHO classification of tumors.
  • - Recent research confirms the prognostic significance of CNS invasion in meningiomas, despite earlier doubts, and highlights the inconsistencies in histopathological evaluations and imaging methods, indicating a need for improved assessments in future classifications.
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Purpose: This study aimed to assess the relationship between mean kurtosis (MK) and mean diffusivity (MD) values from whole-brain diffusion kurtosis imaging (DKI) parametric maps in preoperative magnetic resonance (MR) images from 2016 World Health Organization Classification of Tumors of the Central Nervous System integrated glioma groups.

Methods: Seventy-seven patients with histopathologically confirmed treatment-naïve glioma were retrospectively assessed between 1 August 2013 and 30 October 2017. The area on scatter plots with a specific combination of MK and MD values, not occurring in the healthy brain, was labeled, and the corresponding voxels were visualized on the fluid-attenuated inversion recovery (FLAIR) images.

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Calvarial lesions are rare and can present as a variety of different diseases. The lesions can be palpable on the skin and cause local pain and paraesthesia and, depending on the location, neurological deficits can also occur. This research aims to present an overview of typical imaging features as well as neurosurgical management.

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Rationale And Objectives: Advanced adjuvant therapy of diffuse gliomas can result in equivocal findings in follow-up imaging. We aimed to assess the additional value of dynamic susceptibility perfusion imaging in the differentiation of progressive disease (PD) from pseudoprogression (PsP) in different molecular glioma subtypes.

Materials And Methods: 89 patients with treated diffuse glioma with different molecular subtypes (IDH wild type (Astro-IDH), IDH mutant astrocytomas (Astro-IDH) and oligodendrogliomas), and tumor-suspect lesions on post-treatment follow-up imaging were classified into two outcome groups (PD or PsP) retrospectively by histopathology or clinical follow-up.

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Purpose: To investigate the diagnostic value of three-dimensional morphologic measurements of the Eustachian tube on computed tomography in Eustachian tube dysfunction.

Method: This prospective cross-sectional observational study includes forty patients with unilateral Eustachian tube dysfunction. The clinical diagnosis is verified using the Eustachian tube score - 7 and the Eustachian tube dysfunction questionnaire - 7.

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Identification and localization of ischemic stroke (IS) lesions is routinely performed to confirm diagnosis, assess stroke severity, predict disability and plan rehabilitation strategies using magnetic resonance imaging (MRI). In basic research, stroke lesion segmentation is necessary to study complex peri-infarction tissue changes. Moreover, final stroke volume is a critical outcome evaluated in clinical and preclinical experiments to determine therapy or intervention success.

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Background: The underlying etiology of ischemic stroke remains unknown in up to 30% of patients.

Objectives: This study explored the causal role of complicated (American Heart Association-lesion type VI) nonstenosing carotid artery plaques (CAPs) in cryptogenic stroke (CS).

Methods: CAPIAS (Carotid Plaque Imaging in Acute Stroke) is an observational multicenter study that prospectively recruited patients aged older than 49 years with acute ischemic stroke that was restricted to the territory of a single carotid artery on brain magnetic resonance imaging (MRI) and unilateral or bilateral CAP (≥2 mm, NASCET [North American Symptomatic Carotid Endarterectomy Trial] <70%).

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