T1-weighted 3D Research Articles

Quantitative molecular imaging of cardiac fibrosis and response to treatment using a novel collagen III-specific MR imaging probe

Abstract Background Heart failure (HF) remains a major cause of morbidity and death affecting 64 million people globally[1]. Myocardial fibrosis, characterised by changes in type I (COL1) and III (COL3) collagen levels, may lead to HF [2,3]. Cardiac magnetic resonance (CMR) is a preferred method to detect fibrosis non-invasively, however it provides only indirect measures of fibrosis. Molecular imaging can directly visualise fibrosis, but current imaging probes target COL1. Purpose Here, we developed a COL3-specific probe and used molecular CMR imaging to directly quantify, previously undetectable, COL3 remodelling following myocardial infarction and to monitor treatment response. Methods Myocardial infarction (MI) was induced in mice by permanent ligation of the left anterior descending artery (LAD). Functional and molecular CMR images were acquired at days 10 and 21 post-MI in untreated and mice treated with Enalapril (20mg/kg/day) (n=6/group) using a 3T clinical MRI scanner. A subgroup of untreated mice was also imaged using a negative control probe and Gadovist (n=3). Cardiac function was assessed using 2D short-axis cine images of the left ventricle, and late gadolinium enhancement (LGE) images were obtained using T1-weighted 3D inversion recovery (IR) imaging. T1 mapping was performed using a 2D Look-Locker sequence with thirty inversion recovery images. Results Molecular CMR enabled selective profiling of the natural turnover of COL3 after MI with strong signal enhancement at day 10, and decreased enhancement at day 21 when COL3 is replaced by COL1 (Fig. 1A). Quantitative T1 maps discriminated between infarcted and remote myocardium with lower T1 values in the infarct and higher in the remote myocardium. Importantly, there was no enhancement using the scrambled probe or the clinical agent Gadovist. The imaging data were validated by histology (Fig.1B). Mice treated with Enalapril showed similar enhancement at day 10 compared to untreated mice (Fig. 2A). However, at day 21 mice treated with Enalapril showed higher signal enhancement compared to untreated mice, suggesting that Enalapril may prolong the presence of COL3 in the infarcted myocardium. Quantification of signal enhancement showed the increase in LGE volume and R1 relaxation rates within the infarcted myocardium at day 10, the subsequent decrease at day 21 and the prolongation of the COL3 signal at day 21 in enalapril treated mice (Fig.2B-C) Despite changes in cardiac fibrosis detected with molecular imaging, cardiac function was similar between the groups (Fig. 2D), suggesting that molecular change may precede functional changes. Conclusion(s) Quantitative molecular CMR imaging of COL3 enabled visualisation of changes in COL3 after MI and in response to treatment for the first time. This approach may provide insights into the role of COL3 in cardiac fibrosis and provide an non-invasive method to detect fibrosis early, stage fibrosis and monitor therapeutic response.

A dynamic approach for MR T2-weighted pelvic imaging

T2-weighted 2D fast spin echo sequence serves as the standard sequence in
clinical pelvic MR imaging protocols. However, motion artifacts and blurring caused
by peristalsis present significant challenges. Patient preparation such as administering
antiperistaltic agents is often required before examination to reduce artifacts, which
discomfort the patients. This work introduce a novel dynamic approach for T2
weighted pelvic imaging to address peristalsis-induced motion issue without any patient
preparation.
Approach: A rapid dynamic data acquisition strategy with complementary sampling
trajectory is designed to enable highly undersampled motion-resistant data sampling,
and an unrolling method based on deep equilibrium model is leveraged to reconstruct
images from the dynamic sampled k-space data. Moreover, the fix-point convergence of
the equilibrium model ensures the stability of the reconstruction. The high acceleration
factor in each temporal phase, which is much higher than that in traditional static
imaging, has the potential to effectively freeze pelvic motion, thereby transforming
the imaging problem from conventional motion prevention or removal to motion
reconstruction.
Main results: Experiments on both retrospective and prospective data have
demonstrated the superior performance of the proposed dynamic approach in reducing
motion artifacts and accurately depicting structural details compared to standard static
imaging.
Significance: The proposed dynamic approach effectively captures motion states
through dynamic data acquisition and deep learning-based reconstruction, addressing
motion-related challenges in pelvic imaging.

Enhancement of the lymphatic system following intravenous administration of ferumoxytol.

Lymphatic imaging is becoming increasingly important in the management of patients with congenital heart disease. However, the influence of the intravenous contrast agent ferumoxytol on lymphatic imaging is not well understood. To evaluate the impact of intravenous ferumoxytol on T1-weighted and T2-weighted lymphatic imaging in patients with congenital heart disease. We included consecutive patients receiving ferumoxytol-enhanced 3D angiography for congenital heart disease evaluation. The visibility of the thoracic duct was reviewed on the T1-weighted 3D inversion recovery balanced-steady-state free precession (SSFP) with respiratory navigator gating sequence which is routinely used for angiography and the heavily T2-weighted turbo spin echo sequence which is employed for lymphatic imaging. Data on demographics and time interval between contrast administration and imaging were collected. Statistical analyses were performed using t-tests for continuous variables and chi-squared tests for categorical variables. One hundred nineteen consecutive patients with a mean age of 12.46 years±7.7 years were included. Of these, 45 cases underwent both T1-weighted and T2-weighted imaging; the other 74 underwent only T1-weighted imaging. Of the 45 patients, 20 had thoracic duct enhancement on T1-weighted imaging; among the 26 sedated, only 2 showed enhancement, while 18 of 19 non-sedated patients showed enhancement (P<0.001), indicating a strong association between sedation and reduced thoracic duct visibility. If T2-weighted imaging was performed after contrast administration, the thoracic duct was not visible on those images. For all 45 cases of visible thoracic duct in the entire cohort, the time from contrast administration to imaging ranged from 8 min up to 75 min. The enhancement of the thoracic lymphatic duct on T1-weighted imaging, coupled with degradation observed on T2-weighted imaging, suggests that intravenously administered ferumoxytol rapidly enters the lymphatic fluid. To prevent T2 shortening from degrading the imaging results, T2-weighted imaging for lymphatic evaluation should be performed prior to the administration of ferumoxytol. Sedation and, by inference, fasting may influence this property and warrant further investigation in future studies.

3-1-3 Weight averaging technique-based performance evaluation of deep neural networks for Alzheimer’s disease detection using structural MRI

Alzheimer’s disease (AD) is a progressive neurological disorder. It is identified by the gradual shrinkage of the brain and the loss of brain cells. This leads to cognitive decline and impaired social functioning, making it a major contributor to dementia. While there are no treatments to reverse AD’s progression, spotting the disease’s onset can have a significant impact in the medical field. Deep learning (DL) has revolutionized medical image classification by automating feature engineering, removing the requirement for human experts in feature extraction. DL-based solutions are highly accurate but demand a lot of training data, which poses a common challenge. Transfer learning (TL) has gained attention for its knack for handling limited data and expediting model training. This study uses TL to classify AD using T1-weighted 3D Magnetic Resonance Imaging (MRI) from the Alzheimer’s Disease Neuroimaging (ADNI) database. Four modified pre-trained deep neural networks (DNN), VGG16, MobileNet, DenseNet121, and NASNetMobile, are trained and evaluated on the ADNI dataset. The 3-1-3 weight averaging technique and fine-tuning improve the performance of the classification models. The evaluated accuracies for AD classification are VGG16: 98.75%; MobileNet: 97.5%; DenseNet: 97.5%; and NASNetMobile: 96.25%. The receiver operating characteristic (ROC), precision–recall (PR), and Kolmogorov-Smirnov (KS) statistic plots validate the effectiveness of the modified pre-trained model. Modified VGG16 excels with area under the curve (AUC) values of 0.99 for ROC and 0.998 for PR curves. The proposed approach shows effective AD classification by achieving high accuracy using the 3-1-3 weight averaging technique and fine-tuning.

Preoperative Simulation of Intraoperative Findings in Surgical Clipping of Posterior Communicating Artery Aneurysms Using T2-Weighted 3D Images.

Tentorium resection and detachment from the oculomotor nerve are sometimes required for surgical clipping of unruptured posterior communicating artery (PCoA) aneurysms. Using T2-weighted 3D images, we aimed to identify the preoperative radiological features required to determine the necessity of these additional procedures. We reviewed 30 patients with unruptured PCoA aneurysms who underwent surgical clipping and preoperative simulation using T2-weighted 3D images for measurement of the distance between the tentorium and aneurysm. Aneurysms were classified into superior type (superior to the tentorium) and inferior type (inferior to the tentorium). Seven patients (23%) underwent tentorium resection; all had the inferior type (superior vs. inferior, 0% vs. 33%, p = 0.071). In the 21 patients with the inferior type, the distance from the tentorium to the aneurysmal neck was 2.2 ± 1.1 mm and 0.0 ± 0.5 mm without and with tentorium resection (p < 0.01), respectively. An optimal cutoff value of ≤ +0.84 mm was identified for tentorium resection (area under the curve (AUC) = 0.96). Furthermore, 17 patients (57%) showed tight aneurysm attachment to the oculomotor nerve; all had the inferior type (0% vs. 81%, p < 0.01). The distance from the aneurysm tip to the tentorium was 1.1 ± 1.2 mm and -1.7 ± 1.4 mm without and with attachment (p < 0.01). The optimal cutoff value was ≤ +0.45 mm (AUC = 0.92). Measurement of the distance between the tentorium and aneurysmal neck or tip with T2-weighted 3D images is effective for preoperative simulation for surgical clipping of PCoA aneurysms.

Evaluating the value of individualized 3D printed models for examination, diagnosis and treatment planning of cervical cancer

Background3D printing holds great potential of improving examination, diagnosis and treatment planning as well as interprofessional communication in the field of gynecological oncology. In the current manuscript we evaluated five individualized, patient-specific models of cervical cancer FIGO Stage I-III, created with 3D printing, concerning their value for translational oncology.MethodsMagnetic resonance imaging (MRI) of the pelvis was performed on a 3.0 Tesla MRI, including a T2-weighted isotropic 3D sequence. The MRI images were segmented and transferred to virtual 3D models via a custom-built 3D-model generation pipeline and printed by material extrusion. The 3D models were evaluated by all medical specialties involved in patient care of cervical cancer, namely surgeons, radiologists, pathologists and radiation oncologists. Information was obtained from evaluated profession-specific questionnaires which were filled out after inspecting all five models. The questionnaires included multiple-select questions, questions based on Likert scales (1 = „strongly disagree “ or „not at all useful “ up to 5 = „strongly agree “ or „extremely useful “) and dichotomous questions (“Yes” or “No”).ResultsSurgeons rated the models as useful during surgery (4.0 out of 5) and for patient communication (4.7 out of 5). Furthermore, they believed that the models had the potential to revise the patients’ treatment plan (3.7 out of 5). Pathologists evaluated with mean ratings of 3.0 out of 5 for the usefulness of the models in diagnostic reporting and macroscopic evaluation. Radiologist acknowledged the possibility of providing additional information compared to imaging alone (3.7 out of 5). Radiation oncologists strongly supported the concept by rating the models highly for understanding patient-specific pathological characteristics (4.3 out of 5), assisting interprofessional communication (mean 4.3 out of 5) and communication with patients (4.7 out of 5). They also found the models useful for improving radiotherapy treatment planning (4.3 out of 5).ConclusionThe study revealed that the 3D printed models were generally well-received by all medical disciplines, with radiation oncologists showing particularly strong support. Addressing the concerns and tailoring the use of 3D models to the specific needs of each medical speciality will be essential for realizing their full potential in clinical practice.

Visualization of Cerebrospinal Fluid Outflow and Egress along the Nerve Roots of the Lumbar Spine.

Intrinsic cerebrospinal fluid (CSF) dynamics in the brain have been extensively studied, particularly the egress sites of tagged intrinsic CSF in the meninges. Although spinal CSF recirculates within the central nervous system (CNS), we hypothesized that CSF outflows from the lumbar spinal canal. We aimed to visualize and semi-quantify the outflow using non-contrast MRI techniques. We utilized a 3 Tesla clinical MRI with a 16-channel spine coil, employing time-spatial labeling inversion (Time-SLIP) with tag-on and tag-off acquisitions, T2-weighted coronal 2D fluid-attenuated inversion recovery (FLAIR) and T2-weighted coronal 3D centric ky-kz single-shot FSE (cSSFSE). Images were acquired using time-spatial labeling inversion pulse (Time-SLIP) with tag-on and tag-off acquisitions with varying TI periods. Ten healthy volunteers with no known spinal diseases participated. Variations in tagged CSF outflow were observed across different thoracolumbar nerve root segments in all participants. We quantified CSF outflow at all lumbar levels and the psoas region. There was no significant difference among the ROIs for signal intensity. The tagged CSF outflow from the spinal canal is small but demonstrates egress to surrounding tissues. This finding may pave the way for exploring intrathecal drug delivery, understanding of CSF-related pathologies and its potential as a biomarker for peripheral neuropathy and radiculopathy.

Accelerated High-Resolution Deep Learning Reconstruction Turbo Spin Echo MRI of the Knee at 7 T.

The aim of this study was to compare the image quality of 7 T turbo spin echo (TSE) knee images acquired with varying factors of parallel-imaging acceleration reconstructed with deep learning (DL)-based and conventional algorithms. This was a prospective single-center study. Twenty-three healthy volunteers underwent 7 T knee magnetic resonance imaging. Two-, 3-, and 4-fold accelerated high-resolution fat-signal-suppressing proton density (PD-fs) and T1-weighted coronal 2D TSE acquisitions with an encoded voxel volume of 0.31 × 0.31 × 1.5 mm3 were acquired. Each set of raw data was reconstructed with a DL-based and a conventional Generalized Autocalibrating Partially Parallel Acquisition (GRAPPA) algorithm. Three readers rated image contrast, sharpness, artifacts, noise, and overall quality. Friedman analysis of variance and the Wilcoxon signed rank test were used for comparison of image quality criteria. The mean age of the participants was 32.0 ± 8.1 years (15 male, 8 female). Acquisition times at 4-fold acceleration were 4 minutes 15 seconds (PD-fs, Supplemental Video is available at http://links.lww.com/RLI/A938) and 3 minutes 9 seconds (T1, Supplemental Video available at http://links.lww.com/RLI/A939). At 4-fold acceleration, image contrast, sharpness, noise, and overall quality of images reconstructed with the DL-based algorithm were significantly better rated than the corresponding GRAPPA reconstructions (P < 0.001). Four-fold accelerated DL-reconstructed images scored significantly better than 2- to 3-fold GRAPPA-reconstructed images with regards to image contrast, sharpness, noise, and overall quality (P ≤ 0.031). Image contrast of PD-fs images at 2-fold acceleration (P = 0.087), image noise of T1-weighted images at 2-fold acceleration (P = 0.180), and image artifacts for both sequences at 2- and 3-fold acceleration (P ≥ 0.102) of GRAPPA reconstructions were not rated differently than those of 4-fold accelerated DL-reconstructed images. Furthermore, no significant difference was observed for all image quality measures among 2-fold, 3-fold, and 4-fold accelerated DL reconstructions (P ≥ 0.082). This study explored the technical potential of DL-based image reconstruction in accelerated 2D TSE acquisitions of the knee at 7 T. DL reconstruction significantly improved a variety of image quality measures of high-resolution TSE images acquired with a 4-fold parallel-imaging acceleration compared with a conventional reconstruction algorithm.

Brain and Ventricle Volume Alterations in Idiopathic Normal Pressure Hydrocephalus Determined by Artificial Intelligence-Based MRI Volumetry.

The aim of this study was to employ artificial intelligence (AI)-based magnetic resonance imaging (MRI) brain volumetry to potentially distinguish between idiopathic normal pressure hydrocephalus (iNPH), Alzheimer's disease (AD), and age- and sex-matched healthy controls (CG) by evaluating cortical, subcortical, and ventricular volumes. Additionally, correlations between the measured brain and ventricle volumes and two established semi-quantitative radiologic markers for iNPH were examined. An IRB-approved retrospective analysis was conducted on 123 age- and sex-matched subjects (41 iNPH, 41 AD, and 41 controls), with all of the iNPH patients undergoing routine clinical brain MRI prior to ventriculoperitoneal shunt implantation. Automated AI-based determination of different cortical and subcortical brain and ventricular volumes in mL, as well as calculation of population-based normalized percentiles according to an embedded database, was performed; the CE-certified software mdbrain v4.4.1 or above was used with a standardized T1-weighted 3D magnetization-prepared rapid gradient echo (MPRAGE) sequence. Measured brain volumes and percentiles were analyzed for between-group differences and correlated with semi-quantitative measurements of the Evans' index and corpus callosal angle: iNPH patients exhibited ventricular enlargement and changes in gray and white matter compared to AD patients and controls, with the most significant differences observed in total ventricular volume (+67%) and the lateral (+68%), third (+38%), and fourth (+31%) ventricles compared to controls. Global ventriculomegaly and marked white matter reduction with concomitant preservation of gray matter compared to AD and CG were characteristic of iNPH, whereas global and frontoparietally accentuated gray matter reductions were characteristic of AD. Evans' index and corpus callosal angle differed significantly between the three groups and moderately correlated with the lateral ventricular volumes in iNPH patients [Evans' index (r > 0.83, p ≤ 0.001), corpus callosal angle (r < -0.74, p ≤ 0.001)]. AI-based MRI volumetry in iNPH patients revealed global ventricular enlargement and focal brain atrophy, which, in contrast to healthy controls and AD patients, primarily involved the supratentorial white matter and was marked temporomesially and in the midbrain, while largely preserving gray matter. Integrating AI volumetry in conjunction with traditional radiologic measures could enhance iNPH identification and differentiation, potentially improving patient management and therapy response assessment.

Making acute ischemic stroke thrombi visible in MRI imaging

Knowledge of thrombus behavior and visualization on MRI in acute ischemic stroke is less than optimal. However, MRI sequences could be enhanced based on the typical T1 and T2 relaxation times of the target tissues, which mainly determine their signal intensities on imaging. We studied the relaxation times of a broad spectrum of clot analogs along with their image characteristics of three sequences analyzed: a T1-weighted turbo inversion-recovery sequence (T1w Turbo IR), a T1-weighted turbo spin echo with fat suppression (T1w TSE SPIR), and a T2-weighted 3D TSE with magnetization refocusing to remove T1 dependence (T2w TSE DRIVE). We compared their imaging behavior with the intensity values of normal brain tissue using the same imaging protocols as for clots. Each histological and biochemical clot component contributed to each of the relaxation times. Overall, histological composition correlated strongly with T1 times, and iron content, specifically, with T2 relaxation time. Using decision trees, fibrin content was selected as the primary biomarker for T1 relaxation times, inducing an increase. Up to four clot subgroups could be defined based on its distinctive T1 relaxation time. Clot signal intensity in the T1 and T2-weighted images varied significantly according to T1 and T2 relaxation times. Moreover, in comparison with normal brain tissue intensity values, T2w DRIVE images depict thrombi according to the principle of the more fibrin, the higher the intensity, and in T1w TSE, the more erythrocytes, the higher the intensity. These findings could facilitate improvements in MRI sequences for clot visualization and indicate that T2w DRIVE and T1w TSE sequences should depict the vast majority of acute ischemic stroke thrombi as more hyperintense than surrounding tissues.

Evaluation of spine disorders using high contrast imaging of the cartilaginous endplate.

Introduction: Many spine disorders are caused by disc degeneration or endplate defects. Because nutrients entering the avascular disc are channeled through the cartilaginous endplate (CEP), structural and compositional changes in the CEP may block this solute channel, thereby hindering disc cell function. Therefore, imaging the CEP region is important to improve the diagnostic accuracy of spine disorders. Methods: A clinically available T1-weighted and fat-suppressed spoiled gradient recalled-echo (FS-SPGR) sequence was optimized for high-contrast CEP imaging, which utilizes the short T1 property of the CEP. The FS-SPGR scans with and without breath-hold were performed for comparison on healthy subjects. Then, the FS-SPGR sequence which produced optimal image quality was employed for patient scans. In this study, seven asymptomatic volunteers and eight patients with lower back pain were recruited and scanned on a 3T whole-body MRI scanner. Clinical T2-weighted fast spin-echo (T2w-FSE) and T1-weighted FSE (T1w-FSE) sequences were also scanned for comparison. Results: For the asymptomatic volunteers, the FS-SPGR scans under free breathing conditions with NEX = 4 showed much higher contrast-to-noise ratio values between the CEP and bone marrow fat (BMF) (CNRCEP-BMF) (i.e., 7.8 ± 1.6) and between the CEP and nucleus pulposus (NP) (CNRCEP-NP) (i.e., 6.1 ± 1.2) compared to free breathing with NEX = 1 (CNRCEP-BMF: 4.0 ± 1.1 and CNRCEP-NP: 2.5 ± 0.9) and breath-hold condition with NEX = 1 (CNRCEP-BMF: 4.2 ± 1.3 and CNRCEP-NP: 2.8 ± 1.3). The CEP regions showed bright linear signals with high contrast in the T1-weighted FS-SPGR images in the controls, while irregularities of the CEP were found in the patients. Discussion: We have developed a T1-weighted 3D FS-SPGR sequence to image the CEP that is readily translatable to clinical settings. The proposed sequence can be used to highlight the CEP region and shows promise for the detection of intervertebral disc abnormalities.

Association of vulnerable plaques with white matter hyperintensities on high-resolution magnetic resonance imaging.

One of the widespread manifestations of cerebral small vessel disease (CSVD) of the brain parenchyma is white matter lesion, which appears as white matter hyperintensities (WMHs) on magnetic resonance imaging (MRI). Previous studies have illustrated that large artery atherosclerosis is related to CSVD, but the precise progress of pathogenesis remains unknown. High-resolution MRI (HR-MRI) has the ability to delineate intracranial vascular walls, enabling a thorough exploration of the structure and composition of unstable plaques. This study aimed to apply HR-MRI to characterize the wall changes and plaque characteristics of middle cerebral arteries in patients with WMHs and to investigate the correlation between plaque vulnerability parameters and different degrees of WMHs. In this study, 138 patients with acute ischemic stroke at Harbin Medical University's First Clinical Hospital (May 2021 to October 2023) were cross-sectionally reviewed and underwent conventional brain and HR-MRI using T1-weighted 3D volumetric isotropic turbo spin echo acquisition (T1W-3D-VISTA) of the unilateral middle cerebral artery (MCA). According to Fazekas grade (0-6), the patients were divided into two groups: Fazekas score 0-2, no-or-mild WMHs; and Fazekas 3-6, moderate-to-severe WMHs. The intraplaque hemorrhage, plaque distribution, plaque enhancement, plaque load, remodeling pattern, and stenosis of the two groups were measured. Binary logistic regression analysis was conducted to evaluate the relationship between vulnerable plaques and WMHs. Of the participants who were initially considered for inclusion, 71 were deemed eligible, among whom 34 were placed in the no-or-mild WMH group and 37 in the moderate-to-severe WMH group. Between the two groups, there were significant differences in intraplaque hemorrhage (P=0.01), a wide distribution (P=0.02), and plaque enhancement (P=0.02). Univariate analysis showed that WMHs were associated with age [odds ratio (OR) =1.080; 95% confidence interval (CI): 1.020-1.144; P=0.008], hypertension (OR =3.500; 95% CI: 1.276-9.597; P=0.01), intraplaque hemorrhage (OR =3.955; 95% CI: 1.247-12.538; P=0.02), a wide distribution (OR =3.067; 95% CI: 1.159-8.115; P=0.02), and significant plaque enhancement (OR =4.372; 95% CI: 1.101-17.358; P=0.03); however, the multivariate results showed that the only independent factors associated with WMHs were age (OR =1.095; 95% CI: 1.019-1.176; P=0.01) and intraplaque hemorrhage (OR =5.88; 95% CI: 1.466-23.592; P=0.01). Our findings suggest that age and intraplaque hemorrhage may be associated with more severe WMHs in patients with acute ischemic stroke, which may be helpful for further clinical examination and intervention treatment.

Automated evaluation of hip abductor muscle quality and size in hip osteoarthritis: Localized muscle regions are strongly associated with overall muscle quality

Limited information exists regarding abductor muscle quality variation across its length and which locations are most representative of overall muscle quality. This is exacerbated by time-intensive processes for manual muscle segmentation, which limits feasibility of large cohort analyses. The purpose of this study was to develop an automated and localized analysis pipeline that accurately estimates hip abductor muscle quality and size in individuals with mild-to-moderate hip osteoarthritis (OA) and identifies regions of each muscle which provide best estimates of overall muscle quality.Forty-four participants (age 52.7 ± 16.1 years, BMI 23.7 ± 3.4 kg/m2, 14 males) with and without mild-to-moderate radiographic hip OA were recruited for this study. Unilateral hip magnetic resonance (MR) images were acquired on a 3.0 T MR scanner and included axial T1-weighted fast spin echo and 3D axial Iterative Decomposition of water and fat with Echo Asymmetry and Least-squares estimation (IDEAL-IQ) spoiled gradient-recalled echo (SPGR) with multi-peak fat spectrum modeling and single T2* correction. A three dimensional (3D) V-Net convolutional neural network was trained to automatically segment the gluteus medius (GMED), gluteus minimus (GMIN), and tensor fascia lata (TFL) on axial IDEAL-IQ. Agreement between manual and automatic segmentation and associations between axial fat fraction (FF) estimated from IDEAL-IQ and overall muscle FF were evaluated.Dice scores for automatic segmentation were 0.94, 0.87, and 0.91 for GMED, GMIN, and TFL, respectively. GMED, GMIN, and TFL volumetric and FF measures were strongly correlated (r: 0.92–0.99) between automatic and manual segmentations, where all values fell within the 95% limits of agreement of [−9.79 cm3, 17.43 cm3] and [−1.99%, 2.89%], respectively. Axial FF was significantly associated with overall FF with the strongest correlations at 50%, 50%, and 65% the length of the GMED, GMIN, and TFL muscles, respectively (r: 0.93–0.97). An automated and localized analysis can provide efficient and accurate estimates of hip abductor muscle quality and size across muscle length. Specific regions of the muscle may be used to estimate overall muscle quality in an abbreviated evaluation of muscle quality.

Возможности магнитно-резонансной томографии в диагностике воспалительных изменений парауретральных желез у женщин.

Introduction. Inflammation of the paraurethral glands (skеneitis) is a complex urological disease, often hidden under the guise of other pathological conditions and causing recurrent lower urinary tract infection (UTI) in women. A significant problem for the diagnosis of skineitis at present is the absence or extremely low sensitivity and specificity of available laboratory, instrumental and radiation methods. Thus, the search for new ways to examine patients with recurrent UTI caused by chronic inflammation of the Skene’s glands is an important clinical and socio-economic task of modern healthcare. Materials and methods. The study involved 30 patients aged from 24 to 51 years who underwent magnetic resonance imaging (MRI) of the pelvis with contrast enhancement and targeted examination of the urethra and periurethral area using a device with a 3T fi ld strength. To study the MR semiotics of chronic inflammation of the gallbladder, in addition to standard MR protocols, high-resolution T2-weighted images with a slice thickness of 2 mm and T2-weighted Space 3D images in a sagittal projection with a slice thickness of 1 mm were used. The first group consisted of 16 urologically healthy women without complaints of dysuria, who underwent an assessment of the MRI anatomy of the normal female urethra. MRI of 14 respondents with chronic infl mmation of the paraurethral glands (second group) was performed to search for recurring (natural) changes characteristic of this disease. Such parameters as the diameter of the urethra, the separate thickness of its anterior and posterior walls, clarity at the boundary of the layers, and the presence of pathological changes and formations were studied. Results. Analysis of the obtained tomograms showed that urologically healthy respondents are characterized by symmetrical thickness of the walls of the urethra without pathological formations in it, as well as evenness and clarity of the contour at the boundary of the layers. When studying the results of examination of patients with chronic skeneitis, all of them (100%) noted the following recurring changes: an increase in the diameter of the urethra due to thickening of its posterior wall, in particular the submucosal layer, impaired differentiation at the border of the submucosal and muscular layers, the presence of small cystic changes in the structure of the posterior wall of the urethra (85.7%) or fragmentarily dilated ducts of the urinary tract (14%). Hypertrophy of the bulbospongiosus muscles, detected in 85.7% of respondents in the second group, is likely an indicator of frequent exacerbations and duration of the disease, and can be considered as an additional nonspecific criterion for this disease. Conclusions. These changes can tentatively, given the small sample, be considered pathognomonic MR signs of chronic skineitis. Thus, MRI of the pelvis with a targeted examination of the urethra and periurethral area can help in the differential diagnosis of patients with suspected inflammation of the paraurethral glands, establishing the correct diagnosis and prescribing adequate treatment.

Comparison between postcontrast thin-slice T1-weighted 2D spin echo and 3D T1-weighted SPACE sequences in the detection of brain metastases at 1.5 and 3 T

ObjectivesAccurate detection of metastatic brain lesions (MBL) is critical due to advances in radiosurgery. We compared the results of three readers in detecting MBL using T1-weighted 2D spin echo (SE) and sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) sequences with whole-brain coverage at both 1.5 T and 3 T.MethodsFifty-six patients evaluated for MBL were included and underwent a standard protocol (1.5 T, n = 37; 3 T, n = 19), including postcontrast T1-weighted SE and SPACE. The rating was performed by three raters in two sessions > six weeks apart. The true number of MBL was determined using all available imaging including follow-up. Intraclass correlations for intra-rater and inter-rater agreement were calculated. Signal intensity ratios (SIR; enhancing lesion, white matter) were determined on a subset of 46 MBL > 4 mm. A paired t-test was used to evaluate postcontrast sequence order and SIR. Reader accuracy was evaluated by the coefficient of determination.ResultsA total of 135 MBL were identified (mean/subject 2.41, SD 6.4). The intra-rater agreement was excellent for all 3 raters (ICC = 0.97–0.992), as was the inter-rater agreement (ICC = 0.995 SE, 0.99 SPACE). Subjective qualitative ratings were lower for SE images; however, signal intensity ratios were higher in SE sequences. Accuracy was high in all readers for both SE (R2 0.95–0.96) and SPACE (R2 0.91–0.96) sequences.ConclusionsAlthough SE sequences are superior to gradient echo sequences in the detection of small MBL, they have long acquisition times and frequent artifacts. We show that T1-weighted SPACE is not inferior to standard thin-slice SE sequences in the detection of MBL at both imaging fields.Critical relevance statementOur results show the suitability of 3D T1-weighted turbo spin echo (TSE) sequences (SPACE, CUBE, VISTA) in the detection of brain metastases at both 1.5 T and 3 T.Key points• Accurate detection of brain metastases is critical due to advances in radiosurgery.• T1-weighted SE sequences are superior to gradient echo in detecting small metastases.• T1-weighted 3D-TSE sequences may achieve high resolution and relative insensitivity to artifacts.• T1-weighted 3D-TSE sequences have been recommended in imaging brain metastases at 3 T.• We found T1-weighted 3D-TSE equivalent to thin-slice SE at 1.5 T and 3 T.Graphical

Usefulness of pituitary high-resolution 3D MRI with deep-learning-based reconstruction for perioperative evaluation of pituitary adenomas.

To evaluate the diagnostic value of T1-weighted 3D fast spin-echo sequence (CUBE) with deep learning-based reconstruction (DLR) for depiction of pituitary adenoma and parasellar regions on contrast-enhanced MRI. We evaluated 24 patients with pituitary adenoma or residual tumor using CUBE with and without DLR, 1-mm slice thickness 2D T1WI (1-mm 2D T1WI) with DLR, and 3D spoiled gradient echo sequence (SPGR) as contrast-enhanced MRI. Depiction scores of pituitary adenoma and parasellar regions were assigned by two neuroradiologists, and contrast-to-noise ratio (CNR) was calculated. CUBE with DLR showed significantly higher scores for depicting pituitary adenoma or residual tumor compared to CUBE without DLR, 1-mm 2D T1WI with DLR, and SPGR (p < 0.01). The depiction score for delineation of the boundary between adenoma and the cavernous sinus was higher for CUBE with DLR than for 1-mm 2D T1WI with DLR (p = 0.01), but the difference was not significant when compared to SPGR (p = 0.20). CUBE with DLR had better interobserver agreement for evaluating adenomas than 1-mm 2D T1WI with DLR (Kappa values, 0.75 vs. 0.41). The CNR of the adenoma to the brain parenchyma increased to a ratio of 3.6 (obtained by dividing 13.7, CNR of CUBE with DLR, by 3.8, that without DLR, p < 0.01). CUBE with DLR had a significantly higher CNR than SPGR, but not 1-mm 2D T1WI with DLR. On the contrast-enhanced MRI, compared to CUBE without DLR, 1-mm 2D T1WI with DLR and SPGR, CUBE with DLR improves the depiction of pituitary adenoma and parasellar regions.

Stereotactic body radiotherapy of central lung tumours using a 1.5 T MR-linac: First clinical experiences

BackgroundMRI-guidance may aid better discrimination between Organs at Risk (OARs) and target volumes in proximity of the mediastinum. We report the first clinical experiences with Stereotactic Body Radiotherapy (SBRT) of (ultra)central lung tumours on a 1.5 T MR-linac. Materials and MethodsPatients with an (ultra)central lung tumour were selected for MR-linac based SBRT treatment. A T2-weighted 3D sequence MRI acquired during free breathing was used for daily plan adaption. Prior to each fraction, contours of Internal Target Volume (ITV) and OARs were deformably propagated and amended by a radiation oncologist. Inter-fractional changes in volumes and coverage of target volumes as well as doses in OARs were evaluated in offline and online treatment plans. ResultsTen patients were treated and completed 60 Gy in 8 or 12 fractions. In total 104 fractions were delivered. The median time in the treatment room was 41 min with a median beam-on time of 8.9 min. No grade ≥3 acute toxicity was observed. In two patients, the ITV significantly decreased during treatment (58 % and 37 %, respectively) due to tumour shrinkage. In the other patients, 81 % of online ITVs were within ±15 % of the volume of fraction 1. Comparison with the pre-treatment plan showed that ITV coverage of the online plan was similar in 52 % and improved in 34 % of cases. Adaptation to meet OAR constraints, led to decreased ITV coverage in 14 %. ConclusionsWe describe the workflow for MR-guided Radiotherapy and the feasibility of using 1.5 T MR-linac for SBRT of (ultra) central lung tumours.

Neuroimaging of brain tumors: back to the standardized MRI-protocol

Despite the widespread application of MRI in brain tumor MR-imaging, the standardized MRI protocol has not yet been approved. This fact creates obstacles for interpreting of the obtained data and even limits the diagnostic power of MRI. Standardization of MRI studies facilitates successful planning of surgery, chemotherapy, or radiation therapy and provides more reliable follow-up. In this regard, unification of image acquisition parameters and protocols remains relevant. We propose a standard MRI protocol that includes axial and coronal T2-weighted images, axial or 3D T2-FLAIR, 3D T2* (gradient echo), diffusion-weighted imaging, axial T1-weighted images, contrast-enhanced spin-echo T1-weighted images (either axial or three planes) and obligatory subsequent isotropic 3D T1 images. The following combination of sequences facilitates the correct diagnosis and follow-up. The least magnetic field strength should be 1.5 T.

High signal intensity of the intraaneurysmal sac on T1 CUBE imaging as a predictor of aneurysm stability after coil embolization.

Histopathological studies of aneurysms after coil embolization showed that thrombus formation during the first month after endovascular treatment (EVT) played an important role in the healing process. The authors hypothesized that dedicated T1-weighted imaging may be used to predict stable aneurysms by visualizing the thrombus status within coil-treated aneurysms. Therefore, this study investigated the relationship between the signal intensity (SI) of the intraaneurysmal sac after coil embolization and aneurysm stability. The study population included 82 patients with 86 aneurysms who underwent T1-weighted 3D black-blood fast spin-echo (T1 CUBE) imaging within 1 month after coil embolization between 2019 and 2022. The relative SI of a coil-treated aneurysm (RSIcoiled) was calculated as follows: the mean SI of the intraaneurysmal sac/the mean SI of the genu of the corpus callosum. Aneurysms with enlarged remnants on MR angiography (MRA) within 6 months after EVT were defined as recurrence, while a decrease of intraaneurysmal flow on MRA was defined as improved embolization status. Stable aneurysms were defined as improvement or no change in embolization status 6 months after coil embolization. The volume embolization ratio (VER) was calculated as the ratio of the packed coil volume to the aneurysm volume. Differences between stable and recurrent aneurysms were examined. All aneurysms were divided into high and low RSIcoiled groups based on the cutoff value of RSIcoiled, and differences between the two groups were also evaluated. Recurrence was confirmed for 26 of 86 aneurysms. A univariable analysis showed that small aneurysms, high VER, and high RSIcoiled were associated with aneurysm stability. In the receiver operating characteristic curve analysis, the optimal cutoff value for RSIcoiled to differentiate stable from recurrent aneurysms was 0.54. The cutoff value for RSIcoiled was selected as 0.50 (sensitivity 0.77, specificity 0.70) because it was half the value of the SI of the corpus callosum and close to the optimal cutoff value. In a multivariable analysis, RSIcoiled > 0.50 (OR 8.1, 95% CI 2.5-27) remained a significant factor for aneurysm stability. The high RSIcoiled group showed a higher rate of an improved embolization status (26% vs 6.1%, p = 0.022) and stable aneurysms (85% vs 15%, p = 0.0002). RSIcoiled was associated with postcoiling aneurysm stability. High RSIcoiled might imply intraaneurysmal thrombus formation associated with the healing process of coil-treated aneurysms.

Hand function after neonatal stroke: A graph model based on basal ganglia and thalami structure

IntroductionNeonatal arterial ischemic stroke (NAIS) is a common model to study the impact of a unilateral early brain insult on developmental brain plasticity and the appearance of long-term outcomes. Motor difficulties that may arise are typically related to poor function of the affected (contra-lesioned) hand, but surprisingly also of the ipsilesional hand. Although many longitudinal studies after NAIS have shown that predicting the occurrence of gross motor difficulties is easier, accurately predicting hand motor function (for both hands) from morphometric MRI remains complicated. The hypothesis of an association between the structural organization of the basal ganglia (BG) and thalamus with hand motor function seems intuitive given their key role in sensorimotor function. Neuroimaging studies have frequently investigated these structures to evaluate the correlation between their volumes and motor function following early brain injury. However, the results have been controversial. We hypothesize the involvement of other structural parameters. MethodThe study involves 35 children (mean age 7.3 years, SD 0.4) with middle cerebral artery NAIS who underwent a structural T1-weighted 3D MRI and clinical examination to assess manual dexterity using the Box and Blocks Test (BBT). Graphs are used to represent high-level structural information of the BG and thalami (volumes, elongations, distances) measured from the MRI. A graph neural network (GNN) is proposed to predict children’s hand motor function through a graph regression. To reduce the impact of external factors on motor function (such as behavior and cognition), we calculate a BBT score ratio for each child and hand. ResultsThe results indicate a significant correlation between the score ratios predicted by our method and the actual score ratios of both hands (p < 0.05), together with a relatively high accuracy of prediction (mean L1 distance < 0.03). The structural information seems to have a different influence on each hand’s motor function. The affected hand’s motor function is more correlated with the volume, while the ‘unaffected’ hand function is more correlated with the elongation of the structures. Experiments emphasize the importance of considering the whole macrostructural organization of the basal ganglia and thalami networks, rather than the volume alone, to predict hand motor function. ConclusionThere is a significant correlation between the structural characteristics of the basal ganglia/thalami and motor function in both hands. These results support the use of MRI macrostructural features of the basal ganglia and thalamus as an early biomarker for predicting motor function in both hands after early brain injury.