High-resolution Three-dimensional Magnetic Resonance Research Articles

Characteristics of culprit intracranial plaque without substantial stenosis in ischemic stroke using three-dimensional high-resolution vessel wall magnetic resonance imaging.

We aim to analyze the difference in quantitative features between culprit and non-culprit intracranial plaque without substantial stenosis using three-dimensional high-resolution vessel wall MRI (3D hr-vw-MRI). The patients with cerebral ischemic symptoms of the unilateral anterior circulation were recruited who had non-stenotic intracranial atherosclerosis (<50%) confirmed by computed tomographic angiographic (CTA) or magnetic resonance angiography (MRA). All patients underwent 3D hr-vw MRI within 1 month after symptom onset. 3D hr-vw-MRI characteristics, including wall thickness, plaque burden, enhancement ratio, plaque volume and intraplaque hemorrhage, and histogram features were analyzed based on T2-, precontrast T1-, and post-contrast T1-weighted images. Univariate and multivariate logistic regression analysis were used to identify key determinates differentiating culprit and non-culprit plaques and to calculate the odds ratios (ORs) with 95% confidence intervals (CIs). A total of 150 plaques were identified, of which 133 plaques (97 culprit and 36 non-culprit) were in the middle cerebral artery, three plaques (all culprit) were in the anterior cerebral artery (ACA) and 14 (11 culprit and three non-culprit) were in the internal carotid artery (ICA). Of all the quantitative parameters analyzed, plaque volume, maximum wall thickness, minimum wall thickness, plaque burden, enhancement ratio, coefficient of variation of the most stenotic site, enhancement ratio of whole culprit plaque in culprit plaques were significantly higher than those in non-culprit plaques. Multivariate logistic regression analysis found that plaque volume [OR, 1.527 (95% CI, 1.231-1.894); P < 0.001] and enhancement ratio of whole plaque [OR, 1.095 (95% CI, 1.021-1.175); P = 0.011] were significantly associated with culprit plaque. The combination of the two features obtained a better diagnostic efficacy for culprit plaque with sensitivity and specificity (0.910 and 0.897, respectively) than each of the two parameters alone. 3D hr-vw MRI features of intracranial atherosclerotic plaques provided potential values over prediction of ischemic stroke patients with non-stenotic arteries. The plaque volume and enhancement ratio of whole plaque of stenosis site were found to be effective predictive parameters.

Assessment of the degree of arterial stenosis in intracranial atherosclerosis using 3D high-resolution MRI: comparison with time-of-flight MRA, contrast-enhanced MRA, and DSA

To compare the accuracy of three-dimensional (3D) high-resolution (HR) magnetic resonance imaging (MRI), time-of-flight magnetic resonance angiography (TOF-MRA), contrast-enhanced magnetic resonance angiography (CE-MRA), and digital subtraction angiography (DSA) in measuring the degree of stenosis in intracranial atherosclerosis. All patients with intracranial artery ischaemic events underwent HR-MRI, TOF-MRA, and CE-MRA analysis, and some of these patients underwent DSA examination. The correlation between different methods for measuring the degree of lumen stenosis was analysed. The accuracy of HR-MRI, TOF-MRA, and CE-MRA was evaluated and compared with that of DSA. A total of 189 arterial stenoses were identified in 93 patients. Of these, 72 patients with 142 arterial stenoses underwent DSA examination. A very strong correlation between HR-MRI and CE-MRA measurements was shown (r=0.839, p<0.0001). The correlation between HR-MRI and TOF-MRA measurements was strong (r=0.720, p<0.0001). A very strong correlation between HR-MRI and DSA measurements was found (r=0.864, p<0.0001), and a similar correlation was observed between CE-MRA, and DSA measurements (r=0.843, p<0.0001). The correlation between TOF-MRA and DSA measurements was strong (r=0.686, p<0.0001). There was substantial agreement between HR-MRI and DSA measurements (K=0.772) and between CE-MRA, and DSA measurements (K=0.734) that was slightly higher than the agreement between TOF-MRA and DSA measurements (K=0.636). HR-MRI can accurately measure stenosis (especially for moderate and severe stenosis) in intracranial atherosclerosis by direct visualisation of the vessel lumen and steno-occlusive plaque.

Association between carotid atherosclerosis and presence of intracranial atherosclerosis using three-dimensional high-resolution vessel wall magnetic resonance imaging in asymptomatic patients with type 2 diabetes

AimsCarotid atherosclerosis (CAS) is associated with a high risk of cardiovascular diseases. We aimed to investigate whether CAS is associated with the presence of intracranial atherosclerosis (ICAS). MethodsA total of 69 asymptomatic patients with type 2 diabetes (36 with CAS and 33 without CAS) who were free of cerebrovascular disease were enrolled in this case-control study. CAS was defined as a mean carotid intima-media thickness ≥ 1.0 mm or carotid plaque. The presence of ICAS was identified using three-dimensional high-resolution vessel wall magnetic resonance imaging. ResultsThere was no difference between the case and control groups in baseline characteristics, such as age, the proportion of men, duration of diabetes, and other cardiometabolic risk factors. The prevalence of ICAS was significantly higher in patients with CAS than those without CAS (72.2 % vs 48.5 %, P = 0.044). CAS was significantly associated with the presence of ICAS, even after adjusting other covariates (odds ratio [OR], 3.19; 95 % confidence interval [CI] 1.09–9.33, P = 0.034). In addition, CAS was significantly associated with the presence of multiple ICAS lesions (OR, 5.57; 95 % CI 1.75–17.78, P = 0.004). ConclusionsCAS is significantly and independently associated with the presence and extent of ICAS in asymptomatic patients with type 2 diabetes.

Identification of high-risk intracranial plaques with 3D high-resolution magnetic resonance imaging-based radiomics and machine learning.

Identifying high-risk intracranial plaques is significant for the treatment and prevention of stroke. To develop a high-risk plaque model using three-dimensional (3D) high-resolution magnetic resonance imaging (HRMRI) based radiomics features and machine learning. 136 patients with documented symptomatic intracranial artery stenosis and available HRMRI data were included. Among these patients, 136 and 92 plaques were identified as symptomatic and asymptomatic plaques, respectively. A conventional model was developed by recording and quantifying the radiological plaque characteristics. Radiomics features from T1-weighted images (T1WI) and contrast-enhanced T1WI (CE-T1WI) were used to construct a high-risk plaque model with linear support vector classification (linear SVC). The radiological and radiomics features were combined to build a combined model. Receiver operating characteristic (ROC) curves were used to evaluate these models. Plaque length, burden, and enhancement were independently associated with clinical symptoms and were included in the conventional model, which had an AUC of 0.853 vs. 0.837 in the training and test sets. While the radiomics and the combined model showed an improved AUC: 0.923 vs. 0.925 for the training sets and 0.906 vs. 0.903 in the test sets. Both the radiomics model (p = 0.024, p = 0.018) and combined model (p = 0.042, p = 0.049) outperformed the conventional model in the two sets, whereas the performance of the combined model was not significantly different from that of the radiomics model in the two sets (p = 0.583 and p = 0.606). The radiomics model based on 3D HRMRI can accurately differentiate symptomatic from asymptomatic intracranial arterial plaques and significantly outperforms the conventional model.

Three-Dimensional High-Resolution Magnetic Resonance Imaging for the Assessment of Cervical Artery Dissection.

Background and PurposeDiagnosing cervical artery dissection (CAD) is still a challenge based on the current radiographic criteria. This study aimed to assess the value of three-dimensional high-resolution magnetic resonance imaging (3D HRMRI) in the detection of the signs of CAD and its diagnosis.Materials and MethodsPatients with CAD from January 2016 to January 2021 were recruited from our 3D HRMRI database. The signs of dissection (intramural hematomas, intimal flap, double lumen), length and location of the dissection, thickness of the intramural hematoma, intraluminal thrombus, and percentage of dilation of the outer contour of the dissection on 3D HRMRI were assessed.ResultsFourteen patients with 16 CADs, including 12 carotid CADs and 4 vertebral CADs, were finally diagnosed in this study. On 3D HRMRI, intramural hematomas were detected in 13/16 (81.3%) lesions with high sensitivity (100%) and high specificity (100%). Intimal flaps were found in 9/16 (56.3%) lesions with moderate sensitivity (64.3%) and high specificity (88.9%). Double lumen signs were observed in 4/16 (25.0%) lesions with high sensitivity (80.0%) and high specificity (100%). In addition, concomitant intraluminal thrombus were detected in 4/16 (25.0%) lesions with high sensitivity (80.0%) and high specificity (100%). The mean length of dissection was (25.1 ± 13.7) mm. The mean thickness of the intramural hematoma was (4.3 ± 2.3) mm. The mean percentage of dilation for the outer contour of the dissection was (151.3 ± 28.6)%.ConclusionThe 3D HRMRI enables detection of the dissecting signs, such as intramural hematoma, intimal flap, double lumen, and intraluminal thrombus with high sensitivity and specificity, suggesting a useful, and non-invasive tool for definitively diagnosing CAD.

A probabilistic Bayesian approach to recover map and phase images for quantitative susceptibility mapping.

Undersampling is used to reduce the scan time for high-resolution three-dimensional magnetic resonance imaging. In order to achieve better image quality and avoid manual parameter tuning, we propose a probabilistic Bayesian approach to recover map and phase images for quantitative susceptibility mapping (QSM), while allowing automatic parameter estimation from undersampled data. Sparse prior on the wavelet coefficients of images is interpreted from a Bayesian perspective as sparsity-promoting distribution. A novel nonlinear approximate message passing (AMP) framework that incorporates a mono-exponential decay model is proposed. The parameters are treated as unknown variables and jointly estimated with image wavelet coefficients. Undersampling takes place in the y-z plane of k-space according to the Poisson-disk pattern. Retrospective undersampling is performed to evaluate the performances of different reconstruction approaches, prospective undersampling is performed to demonstrate the feasibility of undersampling in practice. The proposed AMP with parameter estimation (AMP-PE) approach successfully recovers maps and phase images for QSM across various undersampling rates. It is more computationally efficient, and performs better than the state-of-the-art -norm regularization (L1) approach in general, except a few cases where the L1 approach performs as well as AMP-PE. AMP-PE achieves better performance by drawing information from both the sparse prior and the mono-exponential decay model. It does not require parameter tuning, and works with a clinical, prospective undersampling scheme where parameter tuning is often impossible or difficult due to the lack of ground-truth image.

Evaluation of Three-Dimensional High-Resolution Magnetic Resonance Imaging in the Diagnosis of Intracranial Atherosclerotic Stenosis

Evaluation of Three-Dimensional High-Resolution Magnetic Resonance Imaging in the Diagnosis of Intracranial Atherosclerotic Stenosis

Arterial Wall Imaging in Angiographically Occult Spontaneous Subarachnoid Hemorrhage : New Insight into the Usual Suspect.

ObjectiveThe etiology of angiographically occult spontaneous subarachnoid hemorrhage (AOsSAH) is unclear. Three-dimensional (3D) high-resolution vessel wall magnetic resonance imaging (HVM) might be useful in detecting the hidden arterial wall angiopathy in patients with AOsSAH. We aimed to demonstrate the feasibility of HVM for detecting the arterial cause of AOsSAH. MethodsPatients, who were diagnosed with AOsSAH in the first evaluations and underwent HVM, were enrolled. Their clinical and radiologic data were retrospectively reviewed. Especially, focal enhancement of arterial wall on HVM and repetitive catheterized angiograms were precisely compared. ResultsAmong 251 patients with spontaneous SAH, 22 patients were diagnosed with AOsSAH in the first evaluations (8.76%). After excluding three patients who did not undergo 3D-HVM, 19 patients were enrolled and classified as convexal (n=2) or perimesencephalic (n=4), and diffuse (n=13) groups. In convexal and perimesencephalic groups, no focal enhancement on HVM and no positive findings on repetitive angiography were noted. In diffuse group, 10 patients showed focal enhancement of arterial wall on HVM (10/13, 76.9%). Repeated angiography with 3D reconstruction revealed four patients of angiographically positive causative arteriopathy and possible lesion in one case in the concordant location of intramural enhancement on 3D-HVM (5/10, 50%). Three of them were treated with endovascular stent insertion. All patients, except one, recovered with good clinical outcome (3-month modified Rankin score, 0 and 1). Conclusion3D-HVM was useful in detecting hidden true arteriopathy in AOsSAH. It may provide new insights into the etiologic investigation of AOsSAH by proving information about the arterial wall status.

Topographic volume-standardization atlas of the human brain

Specific anatomical patterns are seen in various diseases affecting the brain. Clinical studies on the topography of pathologies are often limited by the absence of a normalization of the prevalence of pathologies to the relative volume of the affected anatomical structures. A comprehensive reference on the relative volumes of clinically relevant anatomical structures serving for such a normalization, is currently lacking. The analyses are based on anatomical high-resolution three-dimensional T1-weighted magnetic resonance imaging data of 30 healthy Caucasian volunteers, including 14 females (mean age 37.79 years, SD 13.04) and 16 males (mean age 38.31 years, SD 16.91). Semi-automated anatomical segmentation was used, guided by a neuroanatomical parcellation algorithm differentiating 96 structures. Relative volumes were derived by normalizing parenchymal structures to the total individual encephalic volume and ventricular segments to the total individual ventricular volume. The present investigation provides the absolute and relative volumes of 96 anatomical parcellation units of the human encephalon. A larger absolute volume in males than in females is found for almost all parcellation units. While parenchymal structures display a trend towards decreasing volumes with increasing age, a significant inverse effect is seen with the ventricular system. The variances in volumes as well as the effects of gender and age are given for each structure before and after normalization. The provided atlas constitutes an anatomically detailed and comprehensive analysis of the absolute and relative volumes of the human encephalic structures using a clinically oriented parcellation algorithm. It is intended to serve as a reference for volume-standardization in clinical studies on the topographic prevalence of pathologies.

Contralesional Structural Plasticity in Different Molecular Pathologic Subtypes of Insular Glioma.

Neuroplasticity may preserve neurologic function in insular glioma, thereby improving prognosis following resection. However, the anatomic and molecular bases of this phenomenon are not known. To address this gap in knowledge, the present study investigated contralesional compensation in different molecular pathologic subtypes of insular glioma by high-resolution three-dimensional T1-weighted structural magnetic resonance imaging. A total of 52 patients with insular glioma were examined. We compared the gray matter volume (GMV) of the contralesional insula according to histological grade [low-grade glioma (LGG) and high-grade glioma (HGG)] and molecular pathology status [isocitrate dehydrogenase (IDH) mutation, telomerase reverse-transcriptase (TERT) promoter mutation, and 1p19q codeletion] by voxel-based morphometry (VBM). A cluster of 320 voxels in contralesional insula with higher GMV was observed in glioma with IDH mutation as compared to IDH wild-type tumors by region of interest-based VBM analysis (family-wise error-corrected at p < 0.05). The GMV of the entire contralesional insula was also larger in insular glioma patients with IDH mutation than in patients with wild-type IDH. However, there was no association between histological grade, TERT promoter mutation, or 1p19q codeletion and GMV in the contralesional insula. Thus, IDH mutation is associated with greater structural compensation in insular glioma. These findings may be useful for predicting neurocognitive and functional outcomes in patients undergoing resection surgery.

Characterisation of symptomatic intracranial plaque without substantial stenosis using high-resolution vessel wall MRI

To characterise symptomatic intracranial plaque without substantial stenosis using three-dimensional (3D) high-resolution contrast-enhanced black-blood magnetic resonance imaging (BBMRI) and to determine plaque features associated with recent cerebrovascular events. The institutional review board approved this retrospective study. The case notes from patients with evidence of intracranial atherosclerosis in a large intracranial artery with preceding BBMRI were reviewed retrospectively. Symptomatic and asymptomatic plaques with substantial luminal stenosis (<50%) were matched by plaque location and patient age. All MRI images were de-identified and interpreted by two neuroradiologists who were blinded to the history of symptoms. Qualitative analyses including the presence of intraplaque haemorrhage (IPH), eccentricity, surface irregularity, and grade of plaque enhancement were recorded. Quantitative analyses including normal wall index and degree of contrast enhancement were calculated. Multivariate regression analysis was performed to identify the association with cerebrovascular ischaemic events. A total of 38 pairs of symptomatic and asymptomatic plaques from 74 patients were analysed. Compared to asymptomatic plaques, symptomatic plaques demonstrated higher degree of contrast enhancement (29.77±19.23 versus 18.21±12.18%, p=0.039) and presence of IPH (26% versus 8%, p=0.032). No significant differences were detected regarding eccentricity, surface irregularity, and normal wall index. Events were associated with contrast enhancement (OR, 1.212; 95% confidence interval [CI], 1.086-1.352) after controlling for age, sex, cardiovascular risk factors, and stenosis degree. IPH was not associated with events. Contrast enhancement in the intracranial plaque without substantial stenosis is associated with previous events, and may serve as the vulnerable feature, thereby stratifying stroke risk not achievable by luminal stenosis.

Three-dimensional MRI-based treatment planning approach for non-invasive ocular proton therapy.

PurposeTo develop a high‐resolution three‐dimensional (3D) magnetic resonance imaging (MRI)‐based treatment planning approach for uveal melanomas (UM) in proton therapy.Materials/methodsFor eight patients with UM, a segmentation of the gross tumor volume (GTV) and organs‐at‐risk (OARs) was performed on T1‐ and T2‐weighted 7 Tesla MRI image data to reconstruct the patient MR‐eye. An extended contour was defined with a 2.5‐mm isotropic margin derived from the GTV. A broad beam algorithm, which we have called πDose, was implemented to calculate relative proton absorbed doses to the ipsilateral OARs. Clinically favorable gazing angles of the treated eye were assessed by calculating a global weighted‐sum objective function, which set penalties for OARs and extreme gazing angles. An optimizer, which we have named OPT’im‐Eye‐Tool, was developed to tune the parameters of the functions for sparing critical‐OARs.ResultsIn total, 441 gazing angles were simulated for every patient. Target coverage including margins was achieved in all the cases (V95% > 95%). Over the whole gazing angles solutions space, maximum dose (Dmax) to the optic nerve and the macula, and mean doses (Dmean) to the lens, the ciliary body and the sclera were calculated. A forward optimization was applied by OPT’im‐Eye‐Tool in three different prioritizations: iso‐weighted, optic nerve prioritized, and macula prioritized. In each, the function values were depicted in a selection tool to select the optimal gazing angle(s). For example, patient 4 had a T2 equatorial tumor. The optimization applied for the straight gazing angle resulted in objective function values of 0.46 (iso‐weighted situation), 0.90 (optic nerve prioritization) and 0.08 (macula prioritization) demonstrating the impact of that angle in different clinical approaches.ConclusionsThe feasibility and suitability of a 3D MRI‐based treatment planning approach have been successfully tested on a cohort of eight patients diagnosed with UM. Moreover, a gaze‐angle trade‐off dose optimization with respect to OARs sparing has been developed. Further validation of the whole treatment process is the next step in the goal to achieve both a non‐invasive and a personalized proton therapy treatment.

A New Method for Aortic Valve Planimetry with High-Resolution 3-Dimensional MRI and Its Comparison with Conventional Cine MRI and Echocardiography for Assessing the Severity of Aortic Valvular Stenosis.

ObjectiveWe aimed to compare the aortic valve area (AVA) calculated using fast high-resolution three-dimensional (3D) magnetic resonance (MR) image acquisition with that of the conventional two-dimensional (2D) cine MR technique.Materials and MethodsWe included 139 consecutive patients (mean age ± standard deviation [SD], 68.5 ± 9.4 years) with aortic valvular stenosis (AS) and 21 asymptomatic controls (52.3 ± 14.2 years). High-resolution T2-prepared 3D steady-state free precession (SSFP) images (2.0 mm slice thickness, 10 contiguous slices) for 3D planimetry (3DP) were acquired with a single breath hold during mid-systole. 2D SSFP cine MR images (6.0 mm slice thickness) for 2D planimetry (2DP) were also obtained at three aortic valve levels. The calculations for the effective AVA based on the MR images were compared with the transthoracic echocardiographic (TTE) measurements using the continuity equation.ResultsThe mean AVA ± SD derived by 3DP, 2DP, and TTE in the AS group were 0.81 ± 0.26 cm2, 0.82 ± 0.34 cm2, and 0.80 ± 0.26 cm2, respectively (p = 0.366). The intra-observer agreement was higher for 3DP than 2DP in one observer: intraclass correlation coefficient (ICC) of 0.95 (95% confidence interval [CI], 0.94–0.97) and 0.87 (95% CI, 0.82–0.91), respectively, for observer 1 and 0.97 (95% CI, 0.96–0.98) and 0.98 (95% CI, 0.97–0.99), respectively, for observer 2. Inter-observer agreement was similar between 3DP and 2DP, with the ICC of 0.92 (95% CI, 0.89–0.94) and 0.91 (95% CI, 0.88–0.93), respectively. 3DP-derived AVA showed a slightly higher agreement with AVA measured by TTE than the 2DP-derived AVA, with the ICC of 0.87 (95% CI, 0.82–0.91) vs. 0.85 (95% CI, 0.79–0.89).ConclusionHigh-resolution 3D MR image acquisition, with single-breath-hold SSFP sequences, gave AVA measurement with low observer variability that correlated highly with those obtained by TTE.

Added diagnostic values of three-dimensional high-resolution proton density-weighted magnetic resonance imaging for unruptured intracranial aneurysms in the circle-of-Willis: Comparison with time-of-flight magnetic resonance angiography.

Advanced imaging methods can enhance the identification of aneurysms of the infundibula, which can reduce unnecessary follow-ups or further work-up, fear, and anxiety in patients. This study aimed to evaluate the added diagnostic value of three-dimensional proton density-weighted vessel wall magnetic resonance imaging (3D-PD MRI) in identifying aneurysms from index lesions refer to vascular bulging lesions without vessels arising from the apex, observed using volume-rendered TOF-MRA in the circle-of-Willis compared with time-of-flight magnetic resonance angiography (TOF-MRA). Retrospective. A total of 299 patients who underwent 3D-PD MRI, digital subtraction angiography (DSA), and TOF-MRA between January 2012 and December 2016 were retrospectively enrolled in this study. 3 Tesla, 3D-PD MRI. Three neuroradiologists independently evaluated TOF-MRA and 3D-PD MRI combined with TOF-MRA for the determination of intracranial aneurysms in patients with index lesions within the circle of Willis. Final diagnoses were made by another neuroradiologist and neurointerventionist in consensus using DSA as the reference standard. The diagnostic performance and proportions of undetermined lesions on TOF-MRA and 3D-PD MRI with TOF-MRA were assessed based on the final diagnoses. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for the diagnosis of unruptured intracranial aneurysms were calculated for each imaging modality. Of 452 lesions identified on volume-rendered TOF-MRA images, 173 (38%) aneurysms and 276 (61%) infundibula were finally diagnosed on DSA. 3D-PD MRI with TOF-MRA showed superior diagnostic performance (p = .001; accuracy, 85.5% versus 95.4%), superior area under the receiver operating characteristic curve over TOF-MRA (p = .001; 0.837 versus 0.947), and a lower proportion of undetermined lesions than TOF-MRA (p = .001; 25.1% versus 2.3%). For unruptured intracranial aneurysms in the circle of Willis, 3D-PD MRI can complement TOF-MRA to improve diagnostic performance and lower the proportion of undetermined lesions.

Intraocular Pressure Decrease Does Not Affect Blood Flow Rate of Ophthalmic Artery in Ocular Hypertension.

PurposeTo investigate if decrease of IOP affects the volumetric blood flow rate in the ophthalmic artery (OA) in patients with previously untreated ocular hypertension.MethodsSubjects with untreated ocular hypertension (n = 30; mean age 67 ± 8 years; 14 females) underwent ophthalmologic examination and a 3-Tesla magnetic resonance imaging investigation. The magnetic resonance imaging included three-dimensional high-resolution phase-contrast magnetic resonance imaging to measure the OA blood flow rate. The subjects received latanoprost once daily in the eye with higher pressure, the untreated eye served as control. The same measurements were repeated approximately 1 week later.ResultsThe mean OA blood flow rate before and after treatment was 12.4 ± 4.4 and 12.4 ± 4.6 mL/min in the treated eye (mean ± SD; P = 0.92) and 13.5 ± 5.2 and 13.4 ± 4.1 mL/min in the control eye (P = 0.92). There was no significant difference between the treated and control eye regarding blood flow rate before (P = 0.13) or after treatment (P = 0.18), or change in blood flow rate after treatment (0.1 ± 3.1 vs. −0.1 ± 4.0 mL/min, P = 0.84). Latanoprost decreased the IOP by 7.2 ± 3.1 mm Hg in the treated eye (P < 0.01).ConclusionsThe results indicate that a significant lowering of IOP does not affect the blood flow rate of the OA in ocular hypertension subjects. The ability to maintain blood supply to the eye independent of the IOP could be a protective mechanism in preserving vision in subjects with ocular hypertension.

Quantitative analysis with volume rendering of pathological myopic eyes by high-resolution three-dimensional magnetic resonance imaging

Discovering a relationship between axial length and vitreous volume would be helpful since the axial length is easier to measure than magnetic resonance imaging (MRI) parameters. This study aimed to analyze the topography of human eyes with pathological myopia through volume rendering images by high-resolution 3D-MRI and to establish a model to estimate the vitreous volume.This was a retrospective, non-randomized, controlled study of patients evaluated at Tongren Hospital from July 7, 2007 to December 12, 2018. The controls were emmetropic volunteers. All participants underwent ophthalmic examinations. Axial length was measured with an IOL Master. High-resolution 3D MRI and volume rendering was utilized for all the eyes. Logistic regression was used to establish a model to predict the vitreous volume.A total of 280 emmetropic eyes and 290 eyes with pathological myopia were included. Males represented 60.7% and 65.5% of the individuals. The mean axial lengths of those two groups were 23.1 ± 0.8 mm (95%CI: 22.7–23.4 mm) and 28.3 ± 2.2 mm (95%CI: 27.5–29.2 mm), respectively (P < .001). The regression model in the pathological myopic group for calculating the vitreous volume according to the axial length was: Vitreous volume = 546.27 × axial length − 6977.12. The regression model in the emmetropic group for calculating the vitreous volume according to the axial length was: Vitreous volume = 458.35 × axial length − 6331.14 (R2 = 0.360, P = .001).Elongation of the axial length is involved in eyeball enlargement in pathological myopic eyes. Measurement of the axial length could be recommended for the estimation of the vitreous volume during vitrectomy if vitreous cavity filling is needed.

A preliminary study of deep learning-based reconstruction specialized for denoising in high-frequency domain: usefulness in high-resolution three-dimensional magnetic resonance cisternography of the cerebellopontine angle.

Deep learning-based reconstruction (DLR) has been developed to reduce image noise and increase the signal-to-noise ratio (SNR). We aimed to evaluate the efficacy of DLR for high spatial resolution (HR)-MR cisternography. This retrospective study included 35 patients who underwent HR-MR cisternography. The images were reconstructed with or without DLR. The SNRs of the CSF and pons, contrast of the CSF and pons, and sharpness of the normal-side trigeminal nerve using full width at half maximum (FWHM) were compared between the two image types. Noise quality, sharpness, artifacts, and overall image quality of these two types of images were qualitatively scored. The SNRs of the CSF and pons were significantly higher with DLR than without DLR (CSF 21.81 ± 7.60 vs. 15.33 ± 4.03, p < 0.001; pons 5.96 ± 1.38 vs. 3.99 ± 0.48, p < 0.001). There were no significant differences in the contrast of the CSF and pons (p = 0.225) and sharpness of the normal-side trigeminal nerve using FWHM (p = 0.185) without and with DLR, respectively. Noise quality and the overall image quality were significantly higher with DLR than without DLR (noise quality 3.95 ± 0.19 vs. 2.53 ± 0.44, p < 0.001; overall image quality 3.97 ± 0.17 vs. 2.97 ± 0.12, p < 0.001). There were no significant differences in sharpness (p = 0.371) and artifacts (p = 1) without and with DLR. DLR can improve the image quality of HR-MR cisternography by reducing image noise without sacrificing contrast or sharpness.

Type 2 Diabetes Mellitus May Exacerbate Gray Matter Atrophy in Patients With Early-Onset Mild Cognitive Impairment.

BackgroundThe precise physiopathological association between the courses of neurodegeneration and cognitive decline in type 2 diabetes mellitus (T2DM) remains unclear. This study sought to comprehensively investigate the distribution characteristics of gray matter atrophy in middle-aged T2DM patients with newly diagnosed mild cognitive impairment (MCI).MethodsFour groups, including 28 patients with early-onset MCI, 28 patients with T2DM, 28 T2DM patients with early-onset MCI (T2DM-MCI), and 28 age-, sex-, and education-matched healthy controls underwent three-dimensional high-resolution structural magnetic resonance imaging. Cortical and subcortical gray matter volumes were calculated, and a structural covariance method was used to evaluate the morphological relationships within the default mode network (DMN).ResultsOverlapped and unique cortical/subcortical gray matter atrophy was found in patients with MCI, T2DM and T2DM-MCI in our study, and patients with T2DM-MCI showed lower volumes in several areas than patients with MCI or T2DM. Volume loss in subcortical areas (including the thalamus, putamen, and hippocampus), but not in cortical areas, was related to cognitive impairment in patients with MCI and T2DM-MCI. No associations between biochemical measurements and volumetric reductions were found. Furthermore, patients with MCI and those with T2DM-MCI showed disrupted structural connectivity within the DMN.ConclusionThese findings provide further evidence that T2DM may exacerbate atrophy of specific gray matter regions, which may be primarily associated with MCI. Impairments in gray matter volume related to T2DM or MCI are independent of cardiovascular risk factors, and subcortical atrophy may play a more pivotal role in cognitive impairment than cortical alterations in patients with MCI and T2DM-MCI. The enhanced structural connectivity within the DMN in patients with T2DM-MCI may suggest a compensatory mechanism for the chronic neurodegeneration.

Visualization of the morphology and pathology of the peripheral branches of the cranial nerves using three-dimensional high-resolution high-contrast magnetic resonance neurography

PurposeTo assess the feasibility and advantages of high-resolution high-contrast magnetic resonance neurography (HRHC-MRN) for visualizing the morphology and pathology of the peripheral branches of cranial nerves. MaterialscMRN (3D SPACE STIR sequence) and HRHC-MRN (contrast enhanced 3D SPACE STIR sequence) were performed at 3 T MR unit on 16 volunteers and 12 patients with head and neck tumors. Quantitative measurements such as SNR, CNR and CR were calculated. Three readers evaluated the continuity of the 10 major peripheral branches of cranial nerves using a 5-score scale (scores 0–4). Interobserver variability was tested. Quantitative measurements and scores were compared between cMRN and HRHC-MRN. The imaging features of the nerve pathology were analyzed. ResultsThe CRs of nerve to bone marrow, nerve to muscle, and nerve to gland were significantly higher with HRHC-MRN than with cMRN (P = 0.014, P = 0.02, P <0.001, respectively). The scores of all nerve trunks were significantly higher with HRHC-MRN than with cMRN (all, P < 0.001). For all nerves on HRHC-MRN, the interobserver consistency was excellent across the three readers (all κ > 0.8). The scores of the inferior alveolar nerve, hypoglossal nerve, lingual nerve, facial nerve, infraorbital nerve, masseteric nerve, glossopharyngeal/vagus nerve, supraorbital nerve, auriculotemporal nerve and buccal nerve were 3.95, 3.77, 3.63, 3.25, 3.15, 3.04, 3.04, 2.87, 2.79, 1.88, respectively. ConclusionHRHC-MRN provides improved visualization of the peripheral branches of cranial nerves and is a promising nerve-selective imaging method for evaluating cranial nerve morphology and pathology.

Practical value of three-dimensional high resolution magnetic resonance Vessel Wall imaging in identifying suspicious intracranial vertebrobasilar dissecting aneurysms

BackgroundDirect evidence of intimal flaps, double lumen and intramural haematomas (IMH) is difficult to detect on conventional angiography in most intracranial vertebrobasilar dissecting aneurysms (VBDAs). Our purpose was to assess the value of three-dimensional high-resolution magnetic resonance vessel wall imaging (3D HRMR VWI) for identifying VBDAs.MethodsBetween August 2013 and January 2016, consecutive patients with suspicious VBDAs were prospectively enrolled to undergo catheter angiography and VWI (pre- and post-contrast). The lesion was diagnosed as definite VBDA when presenting direct signs of dissection; as possible when only presenting indirect signs; and as segmental ectasia when there was local dilation and wall thickness similar to adjacent normal artery’s without mural thrombosis.ResultsTwenty-one patients with 27 lesions suspicious for VBDAs were finally included. Based on findings of VWI and catheter angiography, definite VBDA was diagnosed in 25 and 7 lesions (92.6%, vs 25.9%, p < 0.001), respectively; possible VBDA in 0 and 20 (0 vs 74.1%), respectively; and segmental ectasia in 2 and 0 (7.4% vs 0%), respectively. On VWI and catheter angiography, intimal flap was detected in 21 and 7 lesions (77.8% vs 25.9%, p = 0.001), respectively; double lumen sign in 18 and 7 (66.7% vs 25.9%, p = 0.003), respectively; and IMH sign in 14 and 0 (51.9% vs 0), respectively.Conclusions3D HRMR VWI could detect direct dissection signs more frequently than catheter angiography. This may help obtain definite diagnosis of intracranial VBDAs, and allow accurate differentiation between dissecting aneurysm and segmental ectasia as well. Further prospective study with larger sample was required to investigate the superiority of HRMR VWI for definite diagnosis of intracranial VBDAs than catheter angiography.