Search Results (31)

Background/Objectives: To quantitatively assess lateral geniculate nucleus (LGN) volume using 7 Tesla MRI in patients with Stargardt disease (STGD). Methods: A total of 18 patients with STGD and 15 healthy volunteers were examined with a 7 Tesla MRI of the brain. Measures of LGN volume were performed manually by three independent investigators (radiologists) using ITK-SNAP software, version 4.0.0-rc.2. The volume of the thalamus was evaluated using the open-source automated software package FreeSurfer. Before 7 Tesla MRI, patients underwent ophthalmic examination and 1.5 Tesla MRI. Results: The average LGN volume in both hemispheres was significantly smaller in patients with STGD (right, −111.2 mm³; left, 107.4 mm³) than in the control group (right, −128.7 mm³; left, 123.6 mm³, respectively) (p < 0.0001). The ratio of LGN to thalamus in the right hemisphere was significantly lower (p = 0.024) in the group of patients with STGD (0.014) than in the control group (0.017). Conclusions: The right and left LGN volumes in MR 7T imaging, as well as the right LGN/thalamus ratio, were reduced in patients with STGD compared to controls. 7T MRI using the 3D MT-weighted SILENT protocol provides new insight into structural changes in the brain in retinal dystrophies and offers a possible marker of the response to future therapies in STGD. Full article

Objectives: Methamphetamine (MA) abuse during adolescence can have a significant impact on brain development. On the other hand, regular exercise is known to promote brain health and may have neuroprotective effects. The purpose of this study is to compare brain volumes in three different adolescent groups: those with active methamphetamine use disorder (MUD), adolescent athletes who regularly exercise, and healthy control adolescents. Methods: This MRI study involved three groups of adolescents: 10 with active MUD (9 males, 1 female), nine licensed runner adolescents (three males, six females), and 10 healthy adolescents (5 males, 5 females). Brain volumes were analyzed using T1-weighted images from a 3.0 Tesla MRI scanner, and then segmented automatically with vol2Brain. Statistical analyses included ANCOVA with sex as a covariate and LSD post hoc tests performed using SPSS Statistics 23. Results: Adolescents with MUD showed a 10% increase in total white matter volume compared to the athlete group. Conversely, cortical gray matter volume was reduced by 4% compared to the healthy control group and by 7% compared to the athlete group. The frontal and insular cortices in the MUD group had significantly diminished volumes compared to the athlete group. Overall, individuals with MUD had decreased gray matter volumes and increased white matter volumes in their brains. The brain volumetric differences between the MUD group and the athlete group were statistically significant. Conclusions: The brains of those with MUD displayed a reduction in gray matter volume and an increase in white matter volume, indicating damage from MA on the developing adolescent brain. The volumetric disparities between the MUD and athlete groups were found to be significantly different, suggesting a possible neuroprotective factor of exercise. Further studies are required to explore the potential of exercise-based interventions in alleviating the harmful effects of MA abuse. Full article

Objectives: The purpose was to quantitatively examine brain structures using 7 Tesla MRI in the presence of visual loss caused by retinitis pigmentosa (RP) related to retinitis pigmentosa GTPase regulator (RPGR) gene pathogenic variants. Methods: Twelve male patients with RP (mean visual acuity 0.4) related to confirmed RPGR pathogenic variants and fifteen healthy volunteers were examined with 7 Tesla MRI of the brain. Measures of the lateral geniculate nucleus (LGN) volume were performed manually by three independent investigators (radiologists) using ITK-SNAP (Insight Segmentation and Registration Toolkit) software. Other brain structures were evaluated using the open-source automated software package FreeSurfer. Prior to the 7 Tesla MRI, patients underwent an ophthalmic examination and a 1.5 Tesla MRI. Results: The mean LGN volume (right—100 mm³, left—96 mm³) and left lingual gyrus volume (6162 mm³) were significantly lower in RPGR patients in comparison to the control group (129 mm³, 125 mm³, and 7310 mm³, respectively), whilst some brain regions related to other sensory information such as the left isthmus cingulate (3690 mm³) and entorhinal cortex (right—1564 mm³, left 1734 mm³) were significantly or almost significantly higher in the RPGR group than in the control group (2682 mm³, 960 mm³, and 1030 mm³, respectively). Moreover, compared to the control group, the RPGR group’s thalamus-to-LGN ratio was substantially higher. Conclusions: The use of the 7 Tesla MRI revealed numerous structural abnormalities of the visual pathway in patients with RPGR-related RP. The reorganization of the structures of the brain demonstrated in patients with RPGR-related RP reveals a certain degree of plasticity in response to visual loss. These findings may help improve diagnostic and therapeutic strategies for RP patients and contribute to the development of precision medicine. Full article

Although the stifle joint of wild felines shares several characteristics observed in domestic cats, other characteristics are specific to each species. This study aimed to evaluate the stifle joints of eight Puma concolor, including two young and six adults, through different imaging examinations. All stifles were assessed using radiographs and computed tomography (CT). Magnetic resonance imaging (MRI) was performed on the stifles of one animal using 7 Tesla equipment. In all imaging modalities, the four sesamoid bones were detected. Meniscal mineralization was identified in the stifles of three adult animals and one young animal. The cruciate ligaments and menisci were identified on CT, with MRI providing better visualization. The mean values of CT measurements (cm²) in the sagittal section included patella (2.475), medial fabella (0.481), lateral fabella (0.772), popliteal sesamoid (0.222), and medial meniscus (0.051). No differences were found in HU values between the central trabecular bone of the patella and popliteal sesamoid, the cortical bone of the patella and lateral and medial fabellas, or the cortical bone of the patella and popliteal sesamoid. In conclusion, the descriptions of the stifle of Puma concolor from the different imaging methods contribute to understanding the species and can serve as a basis for identifying alterations. Full article

The implementation of clinical 7T MRI presents both opportunities and challenges for advanced medical imaging. This tutorial provides practical considerations and experiences with 7T MRI in clinical settings. We first explore the history and evolution of MRI technology, highlighting the benefits of increased signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and susceptibility at 7T. Technical challenges such as increased susceptibility artifacts and RF inhomogeneity are also discussed, along with innovative adaptations. This review also discusses hardware and software considerations, including new parallel transmission head coils and advanced image processing techniques to optimize image quality. Safety considerations, such as managing tissue heating and susceptibility to artifacts, are also discussed. Additionally, clinical applications of 7T MRI are examined, focusing on neurological conditions such as epilepsy, multiple sclerosis, and vascular imaging. Emerging trends in the use of 7T MRI for spectroscopy, perfusion imaging, and multinuclear imaging are explored, with insights into the future of ultra-high-field MRI in clinical practice. This review aims to provide clinicians, technologists, and researchers with a roadmap for successfully implementing 7T MRI in both research and clinical environments. Full article

Diffusion magnetic resonance imaging (dMRI) allows for a non-invasive visualization and quantitative assessment of white matter architecture in the brain by characterizing restrictions on the random motion of water molecules. Ultra-high field MRI scanners, such as those operating at 7 Tesla (7T) or higher, can boost the signal-to-noise ratio (SNR) to improve dMRI compared with what is attainable at conventional field strengths such as 3T or 1.5T. However, wavelength effects at 7T cause reduced transmit magnetic field efficiency in the human brain, mainly in the posterior fossa, manifesting as signal dropouts in this region. Recently, we reported a simple approach of using a wireless radiofrequency (RF) surface array to improve transmit efficiency and signal sensitivity at 7T. In this study, we demonstrate the feasibility and effectiveness of the RF enhancer in improving in vivo dMRI at 7T. The electromagnetic simulation results demonstrated a 2.1-fold increase in transmit efficiency with the use of the RF enhancer. The experimental results similarly showed a 1.9-fold improvement in transmit efficiency and a 1.4-fold increase in normalized SNR. These improvements effectively mitigated signal dropouts in regions with inherently lower SNR, such as the cerebellum, resulting in a better depiction of principal fiber orientations and an enhanced visualization of extended tracts. Full article

Perfusion measures of the total vasculature are commonly derived with gradient-echo (GE) dynamic susceptibility contrast (DSC) MR images, which are acquired during the early passes of a contrast agent. Alternatively, spin-echo (SE) DSC can be used to achieve specific sensitivity to the capillary signal. For an improved contrast-to-noise ratio, ultra-high-field MRI makes this technique more appealing to study cerebral microvascular physiology. Therefore, this study assessed the applicability of SE-DSC MRI at 7 T. Forty-one elderly adults underwent 7 T MRI using a multi-slice SE-EPI DSC sequence. The cerebral blood volume (CBV) and cerebral blood flow (CBF) were determined in the cortical grey matter (CGM) and white matter (WM) and compared to values from the literature. The relation of CBV and CBF with age and sex was investigated. Higher CBV and CBF values were found in CGM compared to WM, whereby the CGM-to-WM ratios depended on the amount of largest vessels excluded from the analysis. CBF was negatively associated with age in the CGM, while no significant association was found with CBV. Both CBV and CBF were higher in women compared to men in both CGM and WM. The current study verifies the possibility of quantifying cerebral microvascular perfusion with SE-DSC MRI at 7 T. Full article

(1) Background: Natalizumab dramatically reduces relapses and MRI inflammatory activity (new lesions and enhancing lesions) in multiple sclerosis (MS). Chemical exchange saturation transfer (CEST) MRI can explore brain tissue in vivo with high resolution and sensitivity. We investigated if natalizumab can prevent microstructural tissue damage progression measured with MRI at ultra-high field (7 Tesla) over the first year of treatment. (2) Methods: In this one-year prospective longitudinal study, patients with active relapsing–remitting MS were assessed clinically and scanned at ultra-high-field MRI at the time of their first natalizumab infusion, at 6 and 12 months, with quantitative imaging aimed to detect microstructural changes in the normal-appearing white matter (NAWM), including sequences sensitive to magnetisation transfer (MT) effects from amide proton transfer (MTRAPT) and the nuclear Overhauser effect (MTRNOE). (3) Results: 12 patients were recruited, and 10 patients completed the study. The difference in the T1 relaxation times at month 6 and month 12 of natalizumab treatment was not significant, suggesting the lack of accumulation of tissue damage, while improvements were seen in MTR (MTRAPT and MTRNOE measures) at month 12, suggesting a tissue repair effect. This paralleled the expected lack of clinical and radiological worsening of conventional MRI measures of disease activity (new lesions or gadolinium-enhancing lesions). (4) Conclusion: Natalizumab prevents microstructural brain damage and has effects suggesting an improved white matter microstructure measured at ultra-high field during the first year of treatment. Full article

Background: Diagnostic pathways for prostate cancer (PCa) balance detection rates and burden. MRI impacts biopsy indication and strategy. Methods: A prospectively collected cohort database (N = 496) of men referred for elevated PSA and/or abnormal DRE was analyzed. All underwent biparametric MRI (3 Tesla scanner) and ERSPC prostate risk-calculator. Indication for biopsy was PIRADS ≥ 3 or risk-calculator ≥ 20%. Both targeted (cognitive-fusion) and systematic cores were combined. A hypothetical full-MRI-based pathway was retrospectively studied, omitting systematic biopsies in: (1) PIRADS 1–2 but risk-calculator ≥ 20%, (2) PIRADS ≥ 3, receiving targeted biopsy-cores only. Results: Significant PCa (GG ≥ 2) was detected in 120 (24%) men. Omission of systematic cores in cases with PIRADS 1–2 but risk-calculator ≥ 20%, would result in 34% less biopsy indication, not-detecting 7% significant tumors. Omission of systematic cores in PIRADS ≥ 3, only performing targeted biopsies, would result in a decrease of 75% cores per procedure, not detecting 9% significant tumors. Diagnosis of insignificant PCa dropped by 52%. PCa undetected by targeted cores only, were ipsilateral to MRI-index lesions in 67%. Conclusions: A biparametric MRI-guided PCa diagnostic pathway would have missed one out of six cases with significant PCa, but would have considerably reduced the number of biopsy procedures, cores, and insignificant PCa. Further refinement or follow-up may identify initially undetected cases. Center-specific data on the performance of the diagnostic pathway is required. Full article

The novel approach of our study consists in adapting and in evaluating a custom-made variational autoencoder (VAE) using two-dimensional (2D) convolutional neural networks (CNNs) on magnetic resonance imaging (MRI) images for differentiate soft vs. hard plaque components in peripheral arterial disease (PAD). Five amputated lower extremities were imaged at a clinical ultra-high field 7 Tesla MRI. Ultrashort echo time (UTE), T1-weighted (T1w) and T2-weighted (T2w) datasets were acquired. Multiplanar reconstruction (MPR) images were obtained from one lesion per limb. Images were aligned to each other and pseudo-color red-green-blue images were created. Four areas in latent space were defined corresponding to the sorted images reconstructed by the VAE. Images were classified from their position in latent space and scored using tissue score (TS) as following: (1) lumen patent, TS:0; (2) partially patent, TS:1; (3) mostly occluded with soft tissue, TS:3; (4) mostly occluded with hard tissue, TS:5. Average and relative percentage of TS was calculated per lesion defined as the sum of the tissue score for each image divided by the total number of images. In total, 2390 MPR reconstructed images were included in the analysis. Relative percentage of average tissue score varied from only patent (lesion #1) to presence of all four classes. Lesions #2, #3 and #5 were classified to contain tissues except mostly occluded with hard tissue while lesion #4 contained all (ranges (I): 0.2–100%, (II): 46.3–75.9%, (III): 18–33.5%, (IV): 20%). Training the VAE was successful as images with soft/hard tissues in PAD lesions were satisfactory separated in latent space. Using VAE may assist in rapid classification of MRI histology images acquired in a clinical setup for facilitating endovascular procedures. Full article

Purpose: Diffuse low-grade gliomas (DLGGs) are low-malignancy brain tumors originating from the glial cells of the brain growing continuously and infiltratively along the neural axons and infiltrating the surrounding brain tissue. DLGGs usually transform into higher malignancy, causing progressive disability and premature death. MRI scans are valuable when assessing soft tissue abnormalities, but, due to the infiltrative properties of DLGGs, delineating the tumor borders is a challenging task. Therefore, the aim of this study was to explore the difference in gross tumor volume (GTV) of DLGGs delineated from 7 Tesla and 3 Tesla MRI scans. Method: Patients were recruited at the department of neurosurgery and were scanned in both a 7T and a 3T MRI scanner prior to the operation. Two observers delineated the tumors using semi-automatic delineation software. The results from each observer were blinded to the other observer’s delineation. Results: Comparing GTVs from 7T and 3T, the percentage difference varied up to 40.4% on the T2-weighted images. The percentage difference in GTV varied up to 15.3% on the fluid-attenuated inversion recovery (FLAIR) images. On the T2-weighted images, most cases varied by approximately 15%; on the FLAIR sequence, half of the cases varied by approximately 5% and the other half by approximately 15%. The overall inter-observer agreement was near perfect, with an intraclass correlation of 0.969. The intraclass correlation was better on the FLAIR sequence than on the T2 sequence. Conclusion: Overall, the GTVs delineated from 7T images were smaller. The increase in field strength improved the inter-observer agreement only on the FLAIR sequence. Full article

The pathophysiological mechanisms of overactive bladder syndrome (OAB) remain largely unknown, with major involvement of the central nervous system (CNS). The periaqueductal gray (PAG) is a brainstem area which is indicated to play an essential role in bidirectional communication between the bladder and the CNS. We aimed to assess consistency of PAG functional organization across different bladder sensory states in OAB patients. We propose, that PAG functional organization patterns across sensory states will differ between controls and OAB patients. We analyzed fMRI scans at 7 Tesla from six controls and two OAB patients. The Louvain module detection algorithm was applied to parcellate the PAG in empty and full bladder states. We assessed within-subject consistency and investigated differences in this consistency between both groups. High within-subject agreement of PAG parcellations between empty and full bladder states was demonstrated in both groups. Additionally, we showed that the correlations between PAG clusters in both bladder states were significantly different in patients compared to controls (p = 0.039). The methods introduced here offer a promising tool to assess functional organization of the PAG and understand the underlying pathology and the role of this region in OAB syndrome. Full article

To date, the relationship between central hallmarks of multiple sclerosis (MS), such as white matter (WM)/cortical demyelinated lesions and cortical gray matter atrophy, remains unclear. We investigated the interplay between cortical atrophy and individual lesion-type patterns that have recently emerged as new radiological markers of MS disease progression. We employed a machine learning model to predict mean cortical thinning in whole-brain and single hemispheres in 150 cortical regions using demographic and lesion-related characteristics, evaluated via an ultrahigh field (7 Tesla) MRI. We found that (i) volume and rimless (i.e., without a “rim” of iron-laden immune cells) WM lesions, patient age, and volume of intracortical lesions have the most predictive power; (ii) WM lesions are more important for prediction when their load is small, while cortical lesion load becomes more important as it increases; (iii) WM lesions play a greater role in the progression of atrophy during the latest stages of the disease. Our results highlight the intricacy of MS pathology across the whole brain. In turn, this calls for multivariate statistical analyses and mechanistic modeling techniques to understand the etiopathogenesis of lesions. Full article

The current definition of osteoporosis includes alteration of bone quality. The assessment of bone quality is improved by the development of new texture analysis softwares. Our objectives were to assess if proximal femoral trabecular bone texture measured in Ultra high field (UHF) 7 Tesla MRI and CT scan were related to biomechanical parameters, and if the combination of texture parameters and areal bone mineral density (aBMD) measured by dual-energy X-ray absorptiometry provided a better prediction of femoral failure than aBMD alone. The aBMD of 16 proximal femur ends from eight cadavers were investigated. Nineteen textural parameters were computed in three regions or volumes of interest for each specimen on UHF MRI and CT scan. Then, the corresponding failure load and failure stress were calculated thanks to mechanical compression test. aBMD was not correlated to failure load (R² = 0.206) and stress (R² = 0.153). The failure load was significantly correlated with ten parameters in the greater trochanter using UHF MRI, and with one parameter in the neck and the greater trochanter using CT scan. Eight parameters in the greater trochanter using UHF MRI combined with aBMD improved the failure load prediction, and seven parameters improved the failure stress prediction. Our results suggest that textural parameters provide additional information on the fracture risk of the proximal femur when aBMD is not contributive. Full article

We investigated the presence of misfolded alpha-Synuclein (α-Syn) in minor salivary gland biopsies in relation to substantia nigra pars compacta (SNc) damage measured using magnetic resonance imaging in patients with isolated rapid eye movement sleep behavior disorder (iRBD) and Parkinson’s disease (PD) as compared to healthy controls. Sixty-one participants (27 PD, 16 iRBD, and 18 controls) underwent a minor salivary gland biopsy and were scanned using a 3 Tesla MRI. Deposits of α-Syn were found in 15 (55.6%) PD, 7 (43.8%) iRBD, and 7 (38.9%) controls using the anti-aggregated α-Syn clone 5G4 antibody and in 4 (14.8%) PD, 3 (18.8%) iRBD and no control using the purified mouse anti-α-Syn clone 42 antibody. The SNc damages obtained using neuromelanin-sensitive imaging did not differ between the participants with versus without α-Syn deposits (irrespective of the antibodies and the disease group). Our study indicated that the α-Syn detection in minor salivary gland biopsies lacks sensitivity and specificity and does not correlate with the SNc damage, suggesting that it cannot be used as a predictive or effective biomarker for PD. Full article