Clinical applications of 7T MRI in the brain

AbstractThis review illustrates current applications and possible future directions of 7Tesla (7T) Magnetic Resonance Imaging (MRI) in the field of brain MRI, in clinical studies as well as clinical practice. With its higher signal-to-noise (SNR) and contrast-to-noise ratio (CNR) compared to lower field strengths, high resolution, contrast-rich images can be obtained of diverse pathologies, like multiple sclerosis (MS), brain tumours, aging-related changes and cerebrovascular diseases. In some of these diseases, additional pathophysiological information can be gained compared to lower field strengths. Because of clear depiction of small anatomical details, and higher lesion conspicuousness, earlier diagnosis and start of treatment of brain diseases may become possible. Furthermore, additional insight into the pathogenesis of brain diseases obtained with 7T MRI could be the basis for new treatment developments. However, imaging at high field comes with several limitations, like inhomogeneous transmit fields, a higher specific absorption rate (SAR) and, currently, extensive contraindications for patient scanning. Future studies will be aimed at assessing the advantages and disadvantages of 7T MRI over lower field strengths in light of clinical applications, specifically the additional diagnostic and prognostic value of 7T MRI

Intracranial atherosclerosis assessed with 7-T MRI: Evaluation of patients with ischemic stroke or transient ischemic attack

Background: Intracranial atherosclerosis is an important cause of ischemic stroke and is associated with several vascular risk factors. Current imaging is mainly based on the assessment of luminal narrowing rather than abnormalities in the vessel wall. Purpose: To investigate the relationship between vascular risk factors and atherosclerotic lesion burden of intracranial arteries assessed with vessel wall MRI at 7 T in participants with ischemic stroke or transient ischemic attack (TIA). Materials and Methods: In this prospective study (trial identification number: NTR2119; www.trialregister.nl), study participants who presented with ischemic stroke or TIA of the anterior circulation between December 2009 and September 2017 underwent pre- and postcontrast 7-T vessel wall MRI within 3 months of symptom onset. All large arteries of the intracranial circulation were assessed for number, location, and enhancement of vessel wall lesions. Generalized estimating equations for Poisson regression were used to investigate the relationship between vascular risk factors and number or enhancement of vessel wall lesions. Results: Ninety participants (52 men; mean age, 60 years) were evaluated. Increasing age (relative risk [RR], 1.02; 95% confidence interval [CI]: 1.01, 1.03), hypertension (RR, 1.46; 95% CI: 1.06, 2.02), diabetes mellitus (RR, 1.67; 95% CI: 1.20, 2.33), and a higher multivariable vascular risk score (Second Manifestations of Arterial Disease risk score) (RR, 1.01; 95% CI: 1.00, 1.02) were associated with a higher number of vessel wall lesions in the anterior circulation. Contrast material–enhancing vessel wall lesions were associated only with increasing age (RR, 1.03; 95% CI: 1.01, 1.05). No association was found between smoking and the number of vessel wall lesions. Conclusion: Except for smoking, traditional common cardiovascular risk factors were associated with a higher number and enhancement of intracranial vessel wall lesions at 7-T MRI in individuals evaluated after ischemic stroke or transient ischemic attack

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23 февраля 2011 года исполнилось 75 лет со дня рождения главного инженера Днепродзержинской ГЭС — Кучерявого Владислава Семеновича.15 июня 2011 г. исполняется 70 лет ученому — гидроэнергетику, доктору технических наук, начальнику отдела расчетного обоснования ПАО "Укргидропроект", профессору, заведующему кафедрой гидротехнического строительства Харьковского государственного технического университета строительства и архитектуры Александру Исааковичу Вайнбергу

Intracranial vessel wall lesions on 7T MRI and MRI features of cerebral small vessel disease-The SMART-MR study

The etiology of cerebral small vessel disease (CSVD) is the subject of ongoing research. Although intracranial atherosclerosis (ICAS) has been proposed as a possible cause, studies on their relationship remain sparse. We used 7 T vessel wall magnetic resonance imaging (MRI) to study the association between intracranial vessel wall lesions-a neuroimaging marker of ICAS-and MRI features of CSVD. Within the SMART-MR study, cross-sectional analyses were performed in 130 patients (68 ± 9 years; 88% male). ICAS burden-defined as the number of vessel wall lesions-was determined on 7 T vessel wall MRI. CSVD features were determined on 1.5 T and 7 T MRI. Associations between ICAS burden and CSVD features were estimated with linear or modified Poisson regression, adjusted for age, sex, vascular risk factors, and medication use. In 125 patients, ≥1 vessel wall lesions were found (mean 8.5 ± 5.7 lesions). ICAS burden (per + 1 SD) was associated with presence of large subcortical and/or cortical infarcts (RR = 1.65; 95%CI: 1.12-2.43), lacunes (RR = 1.45; 95% CI: 1.14-1.86), cortical microinfarcts (RR = 1.48; 95%CI: 1.13-1.94), and total white matter hyperintensity volume (b = 0.24; 95%CI: 0.02-0.46). Concluding, patients with a higher ICAS burden had more CSVD features, although no evidence of co-location was observed. Further longitudinal studies are required to determine if ICAS precedes development of CSVD

Lack of genotype-phenotype correlation in basal cell nevus syndrome:A Dutch multicenter retrospective cohort study

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Imaging of intracranial arterial disease: a comparison between MRI and unenhanced CT

BACKGROUND AND PURPOSE: Arterial calcifications on unenhanced CT scans and vessel wall lesions on MRI are often used interchangeably to portray intracranial arterial disease. However, the extent of pathology depicted with each technique is unclear. We investigated the presence and distribution of these two imaging findings in patients with a history of cerebrovascular disease. MATERIALS AND METHODS: We analyzed CT and MRI data from 78 patients admitted for stroke or TIA at our institution. Vessel wall lesions were assessed on 7 T MRI sequences, while arterial calcifications were assessed on CT scans. The number of vessel wall lesions, severity of intracranial internal carotid artery (iICA) calcifications, and overall presence and distribution of the two imaging findings were visually assessed in the intracranial arteries. RESULTS: At least one vessel wall lesion or arterial calcification was assessed in 69 (88%) patients. Only the iICA and vertebral arteries (VA) showed a substantial number of both calcifications and vessel wall lesions. The other vessels showed almost exclusively vessel wall lesions. The number of vessel wall lesions was associated with the severity of iICA calcification ( p  = 0.013). CONCLUSIONS: The number of vessel wall lesions increases with the severity of iICA calcifications. Nonetheless, the distribution of vessel wall lesions on MRI and arterial calcifications on CT shows remarkable differences. These findings support the need for a combined approach to examine intracranial arterial disease

UR-CarA-Net: A Cascaded Framework with Uncertainty Regularization for Automated Segmentation of Carotid Arteries on Black Blood MR Images

We present a fully automated method for carotid artery (CA) outer wall segmentation in black blood MRI using partially annotated data and compare it to the state-of-the-art reference model. Our model was trained and tested on multicentric data of patients (106 and 23 patients, respectively) with a carotid plaque and was validated on different MR sequences (24 patients) as well as data that were acquired with MRI systems of a different vendor (34 patients). A 3D nnU-Net was trained on pre-contrast T1w turbo spin echo (TSE) MR images. A CA centerline sliding window approach was chosen to refine the nnU-Net segmentation using an additionally trained 2D U-Net to increase agreement with manual annotations. To improve segmentation performance in areas with semantically and visually challenging voxels, Monte-Carlo dropout was used. To increase generalizability, data were augmented with intensity transformations. Our method achieves state-of-the-art results yielding a Dice similarity coefficient (DSC) of 91.7% (interquartile range (IQR) 3.3%) and volumetric intraclass correlation (ICC) with ground truth of 0.90 on the development domain data and a DSC of 91.1% (IQR 7.2%) and volumetric ICC with ground truth of 0.83 on the external domain data outperforming top-ranked methods for open-source CA segmentation. The uncertainty-based approach increases the interpretability of the proposed method by providing an uncertainty map together with the segmentation

'We don't know for sure':discussion of uncertainty concerning multigene panel testing during initial cancer genetic consultations

Pre-test counseling about multigene panel testing involves many uncertainties. Ideally, counselees are informed about uncertainties in a way that enables them to make an informed decision about panel testing. It is presently unknown whether and how uncertainty is discussed during initial cancer genetic counseling. We therefore investigated whether and how counselors discuss and address uncertainty, and the extent of shared decision-making (SDM), and explored associations between counselors' communication and their characteristics in consultations on panel testing for cancer. For this purpose, consultations of counselors discussing a multigene panel with a simulated patient were videotaped. Simulated patients represented a counselee who had had multiple cancer types, according to a script. Before and afterwards, counselors completed a survey. Counselors' uncertainty expressions, initiating and the framing of expressions, and their verbal responses to scripted uncertainties of the simulated patient were coded by two researchers independently. Coding was done according to a pre-developed coding scheme using The Observer XT software for observational analysis. Additionally, the degree of SDM was assessed by two observers. Correlation and regression analyses were performed to assess associations of communicated uncertainties, responses and the extent of SDM, with counselors' background characteristics. In total, twenty-nine counselors, including clinical geneticists, genetic counselors, physician assistants-in-training, residents and interns, participated of whom working experience varied between 0 and 25 years. Counselors expressed uncertainties mainly regarding scientific topics (94%) and on their own initiative (95%). Most expressions were framed directly (77%), e.g. We don't know, and were emotionally neutral (59%; without a positive/negative value). Counselors mainly responded to uncertainties of the simulated patient by explicitly referring to the uncertainty (69%), without providing space for further disclosure (66%). More experienced counselors provided less space to further disclose uncertainty (p <0.02), and clinical geneticists scored lower on SDM compared with other types of counselors (p <0.03). Our findings that counselors mainly communicate scientific uncertainties and use space-reducing responses imply that the way counselors address counselees' personal uncertainties and concerns during initial cancer genetic counseling is suboptimal

CXCR4 expression in glioblastoma tissue and the potential for PET imaging and treatment with [Ga-68]Ga-Pentixafor/[Lu-177]Lu-Pentixather

PURPOSE: CXCR4 (over)expression is found in multiple human cancer types, while expression is low or absent in healthy tissue. In glioblastoma it is associated with a poor prognosis and more extensive infiltrative phenotype. CXCR4 can be targeted by the diagnostic PET agent [68Ga]Ga-Pentixafor and its therapeutic counterpart [177Lu]Lu-Pentixather. We aimed to investigate the expression of CXCR4 in glioblastoma tissue to further examine the potential of these PET agents. METHODS: CXCR4 mRNA expression was examined using the R2 genomics platform. Glioblastoma tissue cores were stained for CXCR4. CXCR4 staining in tumor cells was scored. Stained tissue components (cytoplasm and/or nuclei of the tumor cells and blood vessels) were documented. Clinical characteristics and information on IDH and MGMT promoter methylation status were collected. Seven pilot patients with recurrent glioblastoma underwent [68Ga]Ga-Pentixafor PET; residual resected tissue was stained for CXCR4. RESULTS: Two large mRNA datasets (N = 284; N = 540) were assesed. Of the 191 glioblastomas, 426 cores were analyzed using immunohistochemistry. Seventy-eight cores (23 tumors) were CXCR4 negative, while 18 cores (5 tumors) had both strong and extensive staining. The remaining 330 cores (163 tumors) showed a large inter- and intra-tumor variation for CXCR4 expression; also seen in the resected tissue of the seven pilot patients-not directly translatable to [68Ga]Ga-Pentixafor PET results. Both mRNA and immunohistochemical analysis showed CXCR4 negative normal brain tissue and no significant correlation between CXCR4 expression and IDH or MGMT status or survival. CONCLUSION: Using immunohistochemistry, high CXCR4 expression was found in a subset of glioblastomas as well as a large inter- and intra-tumor variation. Caution should be exercised in directly translating ex vivo CXCR4 expression to PET agent uptake. However, when high CXCR4 expression can be identified with [68Ga]Ga-Pentixafor, these patients might be good candidates for targeted radionuclide therapy with [177Lu]Lu-Pentixather in the future