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.

Purpose: To analyze the structural changes in the brain related to combined hearing and vision loss in patients with Usher syndrome (USH) obtained by 7 Tesla MRI. Methods: Twenty patients with a diagnosis of USH and fifteen normal age- and gender-matched subjects were included in this study. USH patients underwent ophthalmological examination. All subjects underwent 7 Tesla MRI of the brain in two sequences: 3D BRAVO T1-weighted and 3D MT-weighted SILENT sequence. Results: Mean values of LGN volumes (right 95.65 mm³, left 88.61 mm³) are significantly (p < 0.001) lower in the USH group than in the control group (right 126.64 mm³, left 120.37 mm³). The average volumes of the left cuneus (4102.85 mm³), right parsorbitalis (2133.95 mm³), and right rostralanteriorcingulate cortex (ACC) (1727.60 mm³) in the patient group are significantly (p = 0.03673, 0.02434, and 0.04204, respectively) lower than in the control group (4673.73 mm³, 2485.13 mm³, and 2060.00 mm³, respectively). Mean lengths of the left lingual cortex (1.99 mm) and right pericalcarine cortex (1.84 mm) in the patient group are significantly (p = 0.02449 and 0.03153, respectively) smaller than in the control group (2.09 mm and 2.0 mm, respectively). Average lengths of the right insula (2.74 mm) in the patient group are significantly (p = 0.00041) greater than in the control group (2.49 mm). Conclusions: Parts of the brain engaged in the visual processing as LGN, pericalcarine cortex, lingual gyrus, and cuneus, are decreased, as well as those involved in hearing and language processing, such as parsorbitalis and ACC. The insula, a higher-order brain area possessing a crucial role in olfactory processing, is increased in USH patients. Our findings enhance the understanding of structural brain abnormalities related to combined hearing and vision loss and suggest complex adaptive changes that should be considered in the development of new visual rehabilitation and restitution strategies in USH patients.

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.

Background/Objectives: To investigate the volume of the lateral geniculate nucleus (LGN) in patients with advanced retinitis pigmentosa (RP). Methods: Nineteen patients with advanced RP (mean age 52 years and mean duration of illness 357 months) and twenty-one age-matched normal subjects have been examined using 7 Tesla MRI of the brain. Brain segmentation was carried out with the “recon-all” function in the FreeSurfer software (version 7.4.1) package. Results: The volumes of the left and right LGN were significantly smaller in those patients with RP, in comparison to the controls. We found a significant positive correlation between the volume of the left LGN and the right eye best-corrected visual acuity in the RP group. Conclusions: Late-stage RP leads to a significant reduction in LGN volume, as measured with 7 Tesla MRI. The volume of the left LGN was correlated with the visual function of the right eye in patients with late-stage RP. The statistical power of the results is limited by there being a low number of RP patients included in this study, which is due to the low prevalence of this rare eye disease.

Background/Objectives: Magnetisation Transfer (MT) MRI is used for neuro-degenerative disorders, including Multiple Sclerosis (MS), providing an indirect measure of large biomolecular MR signal sources which cannot be observed directly because their typical T2 is usually much shorter than the echo time (TE) of conventional MR sequences. We investigated a 3D-radial Zero Time of Echo (ZTE) MT-weighted sequence with potentially enhanced sensitivity to short-T2 MR signals indirectly (via MT weighting) and directly (due to the short TE). Methods: The sequence runs on a human 7T MR scanner, producing whole-brain MT-weighted images with isotropic 0.8 mm resolution in 6.5 minutes. One RF pulse is used to suppress the fat signal and generate MT weighting, reducing RF power deposition to moderate levels. The small excitation pulses and the “quasi-adiabatic” MT pulse mitigate the negative effects of inhomogeneous transmit RF fields observed at 7T in the human head, facilitating the generation of uniform Magnetisation Transfer Ratio (MTR) maps. Results: Results from a biologic phantom, a healthy volunteer, and an MS patient illustrate important imaging features of the “SilentMT” sequence. When the MS patient images were compared with Fluid Attenuated Inversion Recovery (FLAIR) images taken on the same patient at 1.5T and 7T, SilentMT was able to detect all the MS lesions observed on the “reference truth” 1.5T FLAIR; 7T FLAIR, however, failed to detect some lesions in the temporal lobe and brain stem. SilentMT detected a lesion which was not immediately apparent on either FLAIR image. Increased MTR was observed in some regions of the brain of the MS patient, notably the left temporal lobe. Conclusions: This initial investigation of an MT-weighted ZTE sequence shows evidence that it may be more sensitive to pathology in a patient with MS.

Purpose: We aimed to compare the volume of the lateral geniculate nucleus (LGN) in patients with different stages of retinitis pigmentosa (RP) with regard to age, sex and symmetry of the LGN. Methods: The investigated cohort included 13 patients with moderate (median Snellen visual acuity 0.75) and 18 patients with advanced (median Snellen visual acuity 0.06) RP-related visual field loss. The volumes of the left and right LGNs were manually measured using ITK-SNAP software after an examination of the brain with a 7 Tesla MRI. A linear mixed statistical model was used to assess LGN volume regarding age and gender of moderate and advanced RP patients and symmetry of both LGNs. Results: The mixed-effects linear model did not reveal a significant effect of disease group on LGN volume after adjusting for age and sex (F(1.27) = 0.01, p = 0.91). A significant effect of the LGN side was demonstrated, with the volume of the right LGN being significantly greater than that of the left (F(1.29) = 29.45, p < 0.001) in both disease groups, left–right. The interaction between disease group and LGN side was not statistically significant (F(1.29) = 0.45, p = 0.51). There is a tendency for LGN to decrease with age (F(1.27) = 3.84, p = 0.060), and there is no gender predilection (F(1.27) = 0.11, p = 0.74) in RP patients. There was correlation found between left LGN volume and visual acuity (ρ = 0.64) and central retinal thickness (ρ = 0.71) in the moderate group). Conclusions: No significant differences in LGN volume were found between patients with moderate and advanced RP. Furthermore, the volume of the right LGN was larger than the volume of the left LGN in RP patients, and this asymmetry is not gender-dependent. Correlation was found between the left LGN volume and visual acuity and central retinal thickness in moderate group. Our findings may have clinical implications for future RP management.