Podcasts about t2w

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.03.30.534950v1?rss=1 Authors: Saleem, K. S., Avram, A. V., Yen, C. C.-C., Magdoom, K. N., Schram, V., Basser, P. J. Abstract: Subcortical nuclei and other deep brain structures play essential roles in regulating the central and peripheral nervous systems. However, many of these nuclei and their subregions are challenging to identify and delineate in conventional MRI due to their small size, hidden location, and often subtle contrasts compared to neighboring regions. To address these limitations, we scanned the whole brain of the marmoset monkeys in ex vivo using a clinically feasible diffusion MRI method, called the mean apparent propagator (MAP)-MRI, along with T2W and MTR (T1-like contrast) images acquired at 7 Tesla. Additionally, we registered these multimodal MRI volumes to the high-resolution images of matched whole-brain histology sections with seven different stains obtained from the same brain specimens. At high spatial resolution, the microstructural parameters and fiber orientation distribution functions derived with MAP-MRI can distinguish the subregions of many subcortical and deep brain structures, including fiber tracts of different sizes and orientations. The good correlation with multiple but distinct histological stains from the same brain serves as a thorough validation of the structures identified with MAP-MRI and other MRI parameters. Moreover, the anatomical details of deep brain structures found in the volumes of MAP-MRI parameters are not visible in conventional T1W or T2W images. The high-resolution mapping using novel MRI contrasts, combined and correlated with histology, can elucidate structures that were previously invisible radiologically. Thus, this multimodal approach offers a roadmap toward identifying salient brain areas in vivo in future neuroradiological studies. It also provides a useful anatomical standard reference for the region definition of subcortical targets and the generation of a 3D digital template atlas for the marmoset brain research (Saleem et al., 2023). Additionally, we conducted a cross-species comparison between marmoset and macaque monkeys using results from our previous studies (Saleem et al., 2021). We found that the two species had distinct patterns of iron distribution in subregions of the basal ganglia, red nucleus, and deep cerebellar nuclei, confirmed with T2W MRI and histology. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.01.02.522457v1?rss=1 Authors: Baratz, Z., Assaf, Y. Abstract: Magnetic resonance imaging (MRI) is a powerful tool for non-invasive imaging of the human body. However, the quality and reliability of MRI data can be influenced by various factors, such as hardware and software configurations, image acquisition protocols, and preprocessing techniques. In recent years, the introduction of large-scale neuroimaging datasets has taken an increasingly prominent role in neuroscientific research. The advent of publicly available and standardized repositories has enabled researchers to combine data from multiple sources to explore a wide range of scientific inquiries. This increase in scale allows the study of phenomena with smaller effect sizes over a more diverse sample and with greater statistical power. Other than the variability inherent to the acquisition of the data across sites, preprocessing and feature generation steps implemented in different labs introduce an additional layer of variability which may influence consecutive statistical procedures. In this study, we show that differences in the configuration of surface reconstruction from anatomical MRI using FreeSurfer results in considerable changes to the estimated anatomical features. In addition, we demonstrate the effect these differences have on within-subject similarity and the performance of basic prediction tasks based on the derived anatomical features. Our results show that although FreeSurfer may be provided with either a T2w or a FLAIR scan for the same purpose of improving pial surface estimation (relative to based on the mandatory T1w scan alone), the two configurations have a distinctly different effect. In addition, our findings indicate that the similarity of within-subject scans and performance of a range of models for the prediction of sex and age are significantly effected, they are not significantly improved by either of the enhanced configurations. These results demonstrate the large extent to which elementary and sparsely reported differences in preprocessing workflow configurations influence the derived brain features. The results of this study are meant to underline the importance of optimizing preprocessing procedures based on experimental results prior to their distribution and consecutive standardization and harmonization efforts across public datasets. In addition, preprocessing configurations should be carefully reported and included in any following analytical workflows, to account for any variation originating from such differences. Finally, other representations of the raw data should be explored and studied to provide a more robust framework for data aggregation and sharing. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.12.18.520922v1?rss=1 Authors: Orooji, F., Butler, R. Abstract: We apply deep learning to the problem of segmenting the arterial system from T1w and T2w images. We use the freely available 7-Tesla 'forrest' dataset from OpenNeuro, (which contains TOF, T1w, and T2w) and use supervised learning with T1w or T2w as input, and TOF segmentation as ground truth, to train a Unet architecture capable of segmenting arteries and quantifying arterial diameters from T1w or T2w images alone. We demonstrate arterial segmentations from both T1w and T2w images, and show that T2w images have sufficient vessel contrast to estimate arterial diameters comparable to those estimated from TOF. We then apply our Unet to T2w images from a separate dataset (IXI) and show our model generalizes to images acquired at different field strength. We consider this work proof-of concept that arterial segmentations can be derived from MRI sequences with poor contrast between arteries and surrounding tissue (T1w and T2w), due to the ability of deep convolutional networks to extract complex features based on local image intensity. Future work will focus on improving the generalizability of the network to non forrest datasets, with the eventual goal of leveraging the entire pre-existing corpus of neuroimaging data for study of human cerebrovasculature. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.10.16.511844v1?rss=1 Authors: Schira, M. M., Isherwood, Z. J., Kassem, M. S., Barth, M., Shaw, T. B., Roberts, M. M., Paxinos, G. Abstract: We introduce HumanBrainAtlas, an initiative to construct a highly detailed, open-access atlas of the living human brain that combines high-resolution in vivo MR imaging and detailed segmentations previously possible only in histological preparations. Here, we present and evaluate the first step of this initiative: a comprehensive dataset of two healthy male volunteers reconstructed to a 0.25 mm3 isotropic resolution for T1w, T2w and DWI contrasts. Multiple high-resolution acquisitions were collected for each contrast and each participant, followed by averaging using symmetric group-wise normalisation (Advanced Normalisation Tools). The resulting image quality permits structural parcellations rivalling histology-based atlases, while maintaining the advantages of in vivo MRI. For example, components of the thalamus, hypothalamus, and hippocampus - difficult or often impossible to identify using standard MRI protocols, can be identified within the present data. Our data are virtually distortion free, fully 3D, and compatible with existing in vivo Neuroimaging analysis tools. The dataset is suitable for teaching and is publicly available via our website (www.hba.neura.edu.au), which also provides data processing scripts. Instead of focusing on coordinates in an averaged brain space, our approach focuses on providing an example segmentation at great detail in the high quality individual brain, this serves as an illustration on what features contrasts and relations can be used to interpret MRI datasets, in research, clinical and education settings. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

In this Bunker Series episode Pete and Eli and their guest discuss The Elections and the Future of America

In this Bunker Series episode Pete, Eli and their guest discuss The Elections and the Future of America

In this episode Pete and Eli go back into The Bunker and get back to the Bunker series accepting responsibility for all the silliness in the world since they stepped out in August.

In this episode Pete and Eli discuss " A Little Bit Of History Repeating"

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.15.204933v1?rss=1 Authors: Bangalore Yogananda, C. G., Shah, B. R., Yu, F. F., Pinho, M. C., Nalawade, S. S., Murugesan, G. K., Wagner, B. C., Mickey, B., Patel, T., Fei, B., Madhuranthakam, A. J., Maldjian, J. A. Abstract: Background: One of the most important recent discoveries in brain glioma biology has been the identification of the isocitrate dehydrogenase (IDH) mutation and 1p/19q co-deletion status as markers for therapy and prognosis. 1p/19q co-deletion is the defining genomic marker for oligodendrogliomas and confers a better prognosis and treatment response than gliomas without it. Our group has previously developed a highly accurate deep-learning network for determining IDH mutation status using T2-weighted MRI only. The purpose of this study was to develop a similar 1p/19q deep-learning classification network. Methods: Multi-parametric brain MRI and corresponding genomic information were obtained for 368 subjects from The Cancer Imaging Archive (TCIA) and The Cancer Genome Atlas (TCGA). 1p/19 co-deletions were present in 130 subjects. 238 subjects were non co-deleted. A T2w image only network (1p/19q-net) was developed to perform 1p/19q co-deletion status classification and simultaneous single-label tumor segmentation using 3D-Dense-UNets. Three-fold cross-validation was performed to generalize the network performance. ROC analysis was also performed. Dice-scores were computed to determine tumor segmentation accuracy. Results: 1p/19q-net demonstrated a mean cross validation accuracy of 93.46% across the 3 folds (93.4%, 94.35%, and 92.62%, standard dev=0.8) in predicting 1p/19q co-deletion status with a sensitivity and specificity of 0.90 +/- 0.003 and 0.95 +/- 0.01, respectively and a mean AUC of 0.95 +/- 0.01. The whole tumor segmentation mean Dice-score was 0.80 +/- 0.007. Conclusion: We demonstrate high 1p/19q co-deletion classification accuracy using only T2-weighted MR images. This represents an important milestone toward using MRI to predict glioma histology, prognosis, and response to treatment. Copy rights belong to original authors. Visit the link for more info

In this Bunker Series episode Pete and Eli discuss Travel & Tourism

In this Bunker Series episode Pete and Eli discuss The Green Economy

In this Bunker Series episode Pete and Eli discuss Death & Economics

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.01.126375v1?rss=1 Authors: Nalawade, S., Yu, F. F., Bangalore Yogananda, C. G., Murugesan, G. K., Shah, B. R., Pinho, M. C., Wagner, B. C., Mickey, B., Patel, T. R., Fei, B., Madhuranthakam, A. J., Maldjian, J. A. Abstract: Deep learning has shown promise for predicting glioma molecular profiles using MR images. Before clinical implementation, ensuring robustness to real-world problems, such as patient motion, is crucial. We sought to evaluate the effects of motion artifact on glioma marker classifier performance and develop a deep learning motion correction network to restore classification accuracies. T2w images and molecular information were retrieved from the TCIA and TCGA databases. Three-fold cross-validation was used to train and test the motion correction network on artifact-corrupted images. We then compared the performance of three glioma marker classifiers (IDH mutation, 1p/19q codeletion, and MGMT methylation) using motion-corrupted and motion-corrected images. Glioma marker classifier performance decreased markedly with increasing motion corruption. Applying motion correction effectively restored classification accuracy for even the most motion-corrupted images. Robust motion correction can enable high accuracy in deep learning MRI-based molecular marker classification rivaling tissue-based characterization. Copy rights belong to original authors. Visit the link for more info

In this Bunker Series episode Pete and Eli discuss Leadership

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.28.121343v1?rss=1 Authors: Bussy, A., Plitman, E., Patel, R., Tullo, S., Salaciak, A., Bedford, S., Farzin, S., Beland, M.-L., Valiquette, V., Kazazian, C., Tardif, C., Devenyi, G., Chakravarty, M. Abstract: The hippocampus has been extensively studied in various neuropsychiatric disorders throughout the lifespan. However, inconsistent results have been reported with respect to which subfield volumes are most related to age. Here, we investigate whether these discrepancies may be explained by experimental design differences that exist between studies. Multiple datasets were used to collect 1690 magnetic resonance scans from healthy individuals aged 18-95 years old. Standard T1-weighted (T1w; MPRAGE sequence, 1 mm3 voxels), high-resolution T2-weighted (T2w; SPACE sequence, 0.64 mm3 voxels) and slab T2-weighted (Slab; 2D turbo spin echo, 0.4 x 0.4 x 2 mm3 voxels) images were acquired. The MAGeT Brain algorithm was used for segmentation of the hippocampal grey matter (GM) subfields and peri-hippocampal white matter (WM) subregions. Linear mixed-effect models and Akaike information criterion were used to examine linear, second or third order natural splines relationship between hippocampal volumes and age. We demonstrated that stratum radiatum/lacunosum/moleculare and fornix subregions expressed the highest relative volumetric decrease, while the cornus ammonis 1 presented a relative volumetric preservation of its volume with age. We also found that volumes extracted from slab images were often underestimated and demonstrated different age-related relationships compared to volumes extracted from T1w and T2w images. The current work suggests that although T1w, T2w and slab derived subfield volumetric outputs are largely homologous, modality choice plays a meaningful role in the volumetric estimation of the hippocampal subfields. Copy rights belong to original authors. Visit the link for more info

In this Bunker Series episode Pete and Eli discuss Sports entertainment during of the Covid 19 crisis

In this Bunker Series episode Pete and Eli discuss the positives of the covid 19 crisis

In this Bunker Series episode Pete and Eli discuss Vaccines, Boomers vs. Millennials, and Borders

In this episode Pete and Eli introduce The Bunker Series and discuss misinformation, America, and xenophobia

In this episode Pete and Eli discuss Gaza, the history, walls, tunnels, Israeli control, politics, and a new leader

In this world you will have trouble. But take ❤️ heart! I have over come the world. #Hecares #impactingmycommunittally #knowkledgeispowerfulgetit #theuniquenessofatitus2woman #T2W #titus2womanintlinc #DrJLClary

Awake Arise Accomplish ~ We are here to Encourage, Empower, & Edifiy. #impactingmycommunitytally #Knowledgeispowerfulgetit #theuniquenessofatitus2woman #T2W #titus2womanintlinc #DrJLClary

Jeff and Nathalie walk to Siena while discussing the unusual circumstances under which William the Conqueror died. Back in Saint Denis, T2W headquarters, they're joined by William the Conqueror experts Eddie Lehwald and Kara Fuhlbrugge.

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Background: Acute non-traumatic focal subarachnoid haemorrhage (fSAH) is a rare transient ischaemic attack (TIA)-mimic. MRI is considered to be indispensable by some authors in order to avoid misdiagnosis, and subsequent improper therapy. We therefore evaluated the role of CT and MRI in the diagnosis of fSAH patients by comparing our cases to those from the literature. Methods: From 01/2010 to 12/2012 we retrospectively identified seven patients with transient neurological episodes due to fSAH, who had received unenhanced thin-sliced multiplanar CT and subsequent MRI within 3 days on a 1.5 T scanner. MRI protocol included at least fast-field-echo (FFE), diffusion-weighted imaging (DWI), T2-weighted fluid-attenuated inversion recovery (FLAIR) and time-of-flight (TOF) MRA sequences. By using MRI as gold-standard, we re-evaluated images and data from recent publications regarding the sensitivity to detect fSAH in unenhanced CT. Results: fSAH was detected by CT and by FFE and FLAIR on MRI in all of our own cases. However, DWI and T2w-spinecho sequences revealed fSAH in 3 of 7 and 4 of 6 cases respectively. Vascular imaging was negative in all cases. FFE-MRI revealed additional multiple microbleeds and superficial siderosis in 4 of 7 patients and 5 of 7 patients respectively. Including data from recently published literature CT scans delivered positive results for fSAH in 95 of 100 cases (95%), whereas MRI was positive for fSAH in 69 of 69 cases (100%). Conclusions: Thin-sliced unenhanced CT is a valuable emergency diagnostic tool to rule out intracranial haemorrhage including fSAH in patients with acute transient neurological episodes if immediate MRI is not available. However, MRI work-up is crucial and mandatorily has to be completed within the next 24-72 hours.

Background: To determine if black-blood 3 T cardiovascular magnetic resonance (bb-CMR) can depict differences between symptomatic and asymptomatic carotid atherosclerotic plaques in acute ischemic stroke patients. Methods: In this prospective monocentric observational study 34 patients (24 males; 70 +/- 9.3 years) with symptomatic carotid disease defined as ischemic brain lesions in one internal carotid artery territory on diffusion weighted images underwent a carotid bb-CMR at 3 T with fat-saturated pre- and post-contrast T1w-, PDw-, T2w- and TOF images using surface coils and Parallel Imaging techniques (PAT factor = 2) within 10 days after symptom onset. All patients underwent extensive clinical workup (lab, brain MR, duplex sonography, 24-hour ECG, transesophageal echocardiography) to exclude other causes of ischemic stroke. Prevalence of American Heart Association lesion type VI (AHA-LT6), status of the fibrous cap, presence of hemorrhage/thrombus and area measurements of calcification, necrotic core and hemorrhage were determined in both carotid arteries in consensus by two reviewers who were blinded to clinical information. McNemar and Wilcoxon's signed rank tests were use for statistical comparison. A p-value

Background: Previously proposed classifications for carotid plaque and cerebral parenchymal hemorrhages are used to estimate the age of hematoma according to its signal intensities on T1w and T2w MR images. Using these classifications, we systematically investigated the value of cardiovascular magnetic resonance (CMR) in determining the age of vessel wall hematoma (VWH) in patients with spontaneous cervical artery dissection (sCAD). Methods: 35 consecutive patients (mean age 43.6 +/- 9.8 years) with sCAD received a cervical multi-sequence 3T CMR with fat-saturated black-blood T1w-, T2w- and TOF images. Age of sCAD was defined as time between onset of symptoms (stroke, TIA or Horner's syndrome) and the CMR scan. VWH were categorized into hyperacute, acute, early subacute, late subacute and chronic based on their signal intensities on T1w- and T2w images. Results: The mean age of sCAD was 2.0, 5.8, 15.7 and 58.7 days in patients with acute, early subacute, late subacute and chronic VWH as classified by CMR (p < 0.001 for trend). Agreement was moderate between VWH types in our study and the previously proposed time scheme of signal evolution for cerebral hemorrhage, Cohen's kappa 0.43 (p < 0.001). There was a strong agreement of CMR VWH classification compared to the time scheme which was proposed for carotid intraplaque hematomas with Cohen's kappa of 0.74 (p < 0.001). Conclusions: Signal intensities of VWH in sCAD vary over time and multi-sequence CMR can help to determine the age of an arterial dissection. Furthermore, findings of this study suggest that the time course of carotid hematomas differs from that of cerebral hematomas.

Background: Most of the carotid plaque MR studies have been performed using black-blood protocols at 1.5 T without parallel imaging techniques. The purpose of this study was to evaluate a multi-sequence, black-blood MR protocol using parallel imaging and a dedicated 4-channel surface coil for vessel wall imaging of the carotid arteries at 3 T. Materials and methods: 14 healthy volunteers and 14 patients with intimal thickening as proven by duplex ultrasound had their carotid arteries imaged at 3 T using a multi-sequence protocol (time-of-flight MR angiography, pre-contrast T1w-, PDw- and T2w sequences in the volunteers, additional post-contrast T1w- and dynamic contrast enhanced sequences in patients). To assess intrascan reproducibility, 10 volunteers were scanned twice within 2 weeks. Results: Intrascan reproducibility for quantitative measurements of lumen, wall and outer wall areas was excellent with Intraclass Correlation Coefficients >0.98 and measurement errors of 1.5%, 4.5% and 1.9%, respectively. Patients had larger wall areas than volunteers in both common carotid and internal carotid arteries and smaller lumen areas in internal carotid arteries (p < 0.001). Positive correlations were found between wall area and cardiovascular risk factors such as age, hypertension, coronary heart disease and hypercholesterolemia (Spearman's r = 0.45-0.76, p < 0.05). No significant correlations were found between wall area and body mass index, gender, diabetes or a family history of cardiovascular disease. Conclusion: The findings of this study indicate that high resolution carotid black-blood 3 T MR with parallel imaging is a fast, reproducible and robust method to assess carotid atherosclerotic plaque in vivo and this method is ready to be used in clinical practice.

Die Therapie und Nachsorge von Patienten mit uvealem Melanom gehört zu einem der Schwerpunkte der Augenklinik der Ludwig-Maximilians-Universität München. Seit Juni 1997 wurden insgesamt 100 Patienten (51 männlich, 49 weiblich) mit einseitigen uvealen Melanomen an der Augenklinik in Zusammenarbeit mit dem Gamma-Knife-Zentrum München nach einem standardisiertem Verfahren radiochirurgisch mit dem Gamma-Knife behandelt. In diese Studie wurden nur Patienten aufgenommen, die aufgrund der Tumorlokalisation und/oder der Tumorausdehnung (maximale apikale Tumorhöhe > 6mm, basaler Tumordurchmesser > 19mm) nicht mehr für eine konventionelle Brachytherapie geeignet waren. Durch die stereotaktische Präzisionsbestrahlung mit dem Gamma-Knife konnte diesen 100 Patienten die sonst nötige Enukleation des Auges erspart werden. Das mediane Alter der Patienten lag bei Diagnosestellung bei 62 Jahren (95% Konfidenzintervall (KI): 31-82 Jahren). Dabei war der jüngste Patient 24 Jahre und älteste Patient 84 Jahre zum Zeitpunkt der Erstdiagnose alt. Bei 55 Patienten befanden sich die intraokulären Tumoren im rechten Auge (55%), bei 45 Patienten im linken Auge (45%). Die Tumoren zeigten bei den 100 Patienten folgende Verteilung der Lokalisation: 61 Tumoren (61%) waren am hinteren Pol, das bedeutet die Tumoren berühren entweder die Makula und /oder die Papille und /oder einen großen temporalen oder nasalen Gefäßbogen lokalisiert; 21 Tumoren (21%) lagen ausschließlich choroideal in der mittleren Peripherie und 18 Tumoren (18%) befanden sich anterior und bezogen den Ziliarkörper mit ein. Die präoperative maximale apikale Tumorhöhe dieser 100 Patienten lag im Ultraschall bei einem Median von 7,85 mm (95% Konfidenzintervall (KI): 7,3- 8,3 mm). Das im hochauflösenden MRT ermittelte präoperative Tumorvolumen dieser 100 Patienten betrug in der 3D-MPR-Gewichtung im median 735 mm3 (95% KI: 620-880 mm3) und in der T2w Wichtung im median 655 mm3 (95% KI: 560-760 mm3). Unseres Wissens ist diese Studie die Erste, bei der eine Tumorregression bei uvealen Melanomen nach der stereotaktischen Präzisionsbestrahlung mit dem Gamma-Knife sowohl im hochauflösenden MRT als auch im Ultraschall untersucht und einander gegenüber gestellt wird. Eine signifikante Tumorregression wurde nur dann angenommen, wenn der Meßwert der Tumorgröße sich um mehr als zwei Standardabweichungen (2 SD) vom vorherigen Wert unterschied. Für die Ultraschalluntersuchung bedeutete dies, daß eine Tumorregression erst ab einer Größenänderung des Tumors von mehr als 0,36mm als sicher angenommen wurde. Im hochauflösenden MRT wurde in der MPR-3D Wichtung für ein sichere Tumorregression ein Größenänderung von >150mm3 vorausgesetzt, in der T2w Wichtung ein Änderung der Tumorgröße von >170mm3. Tumoren die nach einer kontinuierlichen Regression unter eine Tumorgröße von >0,36mm im Ultraschall und/ oder >150mm3 in der MPR-3D Wichtung beziehungsweise >170mm3 in der T2w Wichtung des hochauflösenden MRT schrumpften, wurden als nicht mehr sicher nachweisbar angesehen. 86 der 100 Patienten mit einem uvealen Melanom konnten in die weitere Untersuchung einer Tumorregression einbezogen werden. Insgesamt vier dieser 86 Patienten verstarben nach Tumorregression an der Fernmetastasierung des Primärtumors. Die Nachbeobachtungszeit dieser 86 Patienten seit der stereotaktischen Behandlung mit dem Gamma-Knife lag im median für das hochauflösende MRT (MPR-3D, T2w) bei 468,5 Tagen (95% KI: 347-611 Tagen) und im Ultraschall bei 528,5 Tagen (95% KI: 497,0- 595,0 Tagen). Bei 81 der 86 Patienten konnte eine signifikante Tumorregression nach der stereotaktischen Bestrahlung im hochauflösende MRT (MPR-3D, T2w) nachgewiesen werden. Nach einer Beobachtungszeit vom im median 73,0 Tagen (95% KI: 58,0- 84,0 Tage) zeigte sich in der MPR-3D gewichteten Sequenz des MRT eine signifikante Tumorregression. In der T2w gewichteten Sequenz betrug diese Zeit im median 78,0 Tage (95% KI: 61,0-92,0 Tage). Echographisch ließ bei 63 der 86 Patienten eine signifikante Tumorregression nach der sereotaktischen Präzisionsbestrahlung im Ultraschall nachweisen. Diese signifikante Tumorregression wurde im Ultraschall nach einer Nachbeobachtungszeit vom im median 137,0 Tagen (95% KI: 92,0- 182,0 Tagen) festgestellt. Der Unterschied bis zum Zeitpunkt (in Tagen) einer signifikanten Tumorregression zwischen hochauflösenden MRT(MPR-3D, T2w) und Ultraschall ist signifikant (p< 0,001). Bei 63 dieser 86 Patienten zeigte sich die Tumorregression nach der stereotaktischen Präzisionsbestrahlung mit dem Gamma-Knife zuerst im hochauflösenden MRT(MPR-3D, T2w), bei 10 dieser 86 Patienten ließ sich diese zuerst im Ultraschall feststellen. Bei 89 dieser 100 Patienten konnte untersucht werden, ob und wann der Tumor nach kontinuierlicher Regression nicht mehr durch das hochauflösende MRT und/oder Ultraschall nachgewiesen werden kann. Insgesamt vier dieser 86 Patienten verstarben nach Tumorregression an Fernmetastasen des Primärtumors. Die Nachbeobachtungszeit dieser 89 Patienten betrug seit der stereotaktischen Behandlung mit dem Gamma-Knife im median für das hochauflösende MRT (MPR-3D, T2w) 431,0 Tagen (95% KI: 346,0- 609,0 Tagen) und im Ultraschall 531,0 Tagen (95% KI: 497,0-668,0 Tagen). Nach einer kontinuierlichen Tumorregression lag die geschrumpfte Tumorrestgröße bei 37 der 89 Patienten unter der sicheren Nachweisbarkeitsgrenze des hochauflösenden MRT in der 3D-MPR Wichtung. Die Beobachtungszeit bis die Tumorrestgröße unter die Nachweisbarkeit des hochauflösenden MRT in der 3D-MPR Wichtung fiel betrug dabei im median 284,0 Tage (95% KI: 202,0- 365,0 Tage). In der T2w Wichtung des hochauflösenden MRT fiel bei 38 der 89 Patienten die Tumorgröße nach der stereotaktischen Präzisionsbestrahlung mit dem Gamma-Knife unter die Grenze der sicheren Nachweisbarkeit des Tumors. Dabei betrug die Zeit bis der Tumor nach kontinuierlicher Regression unter die Nachweisbarkeitsgrenze des hochauflösenden MRT in der T2w Wichtung fiel im median 279,5 Tage (95% KI: 186,0- 359,0 Tage). Im Gegensatz dazu ließ sich der Tumor nach kontinuierlicher Regression bei allen 89 Patienten mit dem Ultraschall nachweisen. Die maximale apikale Tumorhöhe der 37 Patienten, die sich mit dem MRT nicht mehr sicher nachweisen ließen, betrug im median 3,8mm (95% KI: 3,0- 4,6 mm). Bei den 38 Patienten, die nicht mehr sicher mit dem MRT in der T2w Wichtung nachgewiesen wurden, lag die maximale apikale Tumorhöhe im median bei 3,9 mm (95% KI: 3,0- 4,6 mm). Zusammenfassend ist somit festzuhalten, das ein Ansprechen von uvealen Melanom auf die stereotaktische Präzisionsbestrahlung mit dem Gamma-Knife im Sinne einer Tumorregression zuerst im hochauflösenden MRT gesichert werden kann, bevor dies mit dem Ultraschall möglich ist. Anderseits können Regression- und / oder Vernarbungszeichen uveale Melanome mit dem Ultraschall in der weiteren Verlaufkontrolle noch nachgewiesen werden, während diese bereits mit dem hochauflösenden MRT nicht mehr sicher möglich ist.