BACKGROUND: Stricturing, penetrating complications and extraintestinal manifestations (EIMs) are frequent in patients with inflammatory bowel disease (IBD). There is limited data on the prevalence of these complications in patients with IBD. Therefore, we aimed to assess the burden of these complications detected incidentally on cross-sectional imaging.
METHODS: A retrospective study conducted at two tertiary care centers in London, Ontario. Patients (≥18 years) with a confirmed diagnosis of IBD who underwent CT enterography (CTE) or MR enterography (MRE) between 1 Jan 2010 and 31 Dec 2018 were included. Categorical variables were reported as proportions and the mean and standard deviations were reported for continuous variables.
RESULTS: A total of 615 imaging tests (MRE: 67.3% [414/615]) were performed in 557 IBD patients (CD: 91.4% [509/557], UC: 8.6% [48/557]). 38.2% (213/557) of patients were male, with mean age of 45.6 years (±15.8), and median disease duration of 11.0 years (±12.5). Among patients with CD, 33.2% (169/509) had strictures, with 7.8% having two or more strictures and 66.3% considered inflammatory. A fistula was reported in 10.6% (54/509), the most common being perianal fistula (27.8% [15/54]), followed by enterocutaneous fistula (16.8% [9/54]), and enteroenteric fistula (16.8% [9/54]). Additionally, 7.4% (41/557) of patients with IBD were found to have an EIM on cross-sectional imaging, with the most prevalent EIM being cholelithiasis (63.4% [26/41]), followed by sacroiliitis (24.4% [10/41]), primary sclerosing cholangitis (4.8% [2/41]) and nephrolithiasis (4.8% [2/41]).
CONCLUSIONS: Approximately 40% of patients with CD undergoing cross-sectional imaging had evidence of a stricture or fistulizing disease, with 7% of patients with IBD having a detectable EIM. These results highlight the burden of disease and the need for specific therapies for these disease phenotypes.

This paper introduces an electromagnetic structure utilizing the controllable mechanical properties of magnetorheological elastomer (MRE) materials through magnetic flux. An adaptive elastic foundation composed of these materials is explored for vibration reduction and frequency modulation. This study investigates these effects using both a single-mass model and a coupled human-seat model. For objects supported by the adaptive elastic foundation, increasing the magnetic flux enhances the stiffness and damping, thereby significantly reducing the peak response while slightly increasing the resonance frequency. Strategies such as increasing the magnetic flux, reducing the object mass, and minimizing the system\'s degrees of freedom and internal damping contribute to enhancing the vibration reduction and frequency modulation in the adaptive elastic foundation. The simulation results indicate that for a seated human (weighing between 72.4 kg and 88.4 kg), the adaptive elastic foundation reduces the head peak response by approximately 15.7% and increases the resonance frequency by approximately 3.4% at a magnetic flux of 138 mT.

OBJECTIVE: To compare hepatic stiffness and fat fraction in patients with obesity and type 1 diabetes (T1D) with type 2 diabetes (T2D) with a similar body mass index (BMI).
METHODS: In this prospective cross-sectional study, 90 participants with T1D (BMI 30.5 ± 4.5 kg/m2; diabetes duration 20.5 ± 9.8 years; HbA1c 8.2% ± 1.4%) and 69 with T2D (BMI: 30.8 ± 4.6 kg/m2; diabetes duration: 11.7 ± 7.8 years; HbA1c: 7.3% ± 1.4%) were included. Liver fat fraction and stiffness were examined by magnetic resonance imaging and elastography, respectively. Logistic regressions were used to evaluate associations with biomedical variables.
RESULTS: The mean liver stiffness score in patients with obesity and T1D was 2.2 ± 0.5 kPa, while in T2D it was 2.6 ± 0.8 kPa (P < .001). The liver fat fraction in patients with obesity and T1D was 3.7% ± 6.3%, and in T2D it was 10.6% ± 7.9% (P < .001). Metabolic dysfunction-associated steatotic liver disease (MASLD) was present in 13.3% of patients with T1D and in 69.6% of patients with T2D, whereas fibrosis was suggested in 7.8% of patients with T1D and in 27.5% of patients with T2D. Liver stiffness was four times higher in patients with T2D compared with those with T1D (odds ratio = 5.4, 95% confidence interval: 2.1-13.6, P < .001). Aspartate transaminase (AST), alanine transaminase, gamma-glutamyl transferase (GGT), triglycerides and the android-to-gynoid ratio were associated with elevated fat fraction in both cohorts. AST and GGT were associated with elevated liver stiffness in both cohorts.
CONCLUSIONS: Patients with obesity and T1D had lower liver fat and liver stiffness compared with those patients with T2D, despite similar levels of BMI, a longer duration of diabetes and worse glycaemic control.

暂无摘要。

BACKGROUND: MR elastography (MRE) at 60 Hz is widely used for staging liver fibrosis. MRE with lower frequencies may provide inflammation biomarkers.
OBJECTIVE: To establish a practical simultaneous dual-frequency liver MRE protocol at both 30 Hz and 60 Hz during a single examination and validate the occurrence of second harmonic waves at 30 Hz.
METHODS: Retrospective.
METHODS: One hundred six patients (48 females, age: 50.0 ± 13.4 years) were divided as follows: Cohort One (15 patients with chronic liver disease [CLD] and 25 healthy volunteers) with simultaneous dual-frequency MRE. Cohort Two (66 patients with CLD) with second harmonic MRE.
UNASSIGNED: 3-T, single- or dual-frequency MRE at 30 Hz and 60 Hz.
RESULTS: Liver stiffness (LS) in both cohorts was evaluated with manually placed volumetric ROIs by two independent analyzers. Image quality was assessed by three independent readers on a 4-point scale (0-3: none/failed, fair, moderate, excellent) based on the depth of wave propagation with 1/3 incremental penetration. The success rate was derived from the percentage of nonzero quality scores.
METHODS: Measurement agreement, bias, and repeatability of LS were assessed using intraclass correlation coefficients (ICCs), Bland-Altman plots, and repeatability coefficient (RC). Mann-Whitney U tests were used to evaluate the differences in image quality between different methods. A P-value <0.05 was considered statistically significant.
RESULTS: Success rate was 97.5% in Cohort One and 91% success rate for the second harmonic MRE in Cohort Two. The second harmonic and conventional MRE showed excellent agreement in LS (all ICCs >0.90). The quality scores for the second harmonic wave images were lower than those from the conventional MRE (Z = -4.523).
CONCLUSIONS: Compared with conventional and second harmonic methods, simultaneous dual-frequency had better image quality, high success rate and the advantage of intrinsic co-registration, while the second harmonic method can be an alternative if custom waveform is not available.
METHODS: 3 TECHNICAL EFFICACY: Stage 1.

BACKGROUND: We investigated the potential of magnetic resonance elastography (MRE) stiffness measurements in skeletal muscles as an outcome measure, by determining its test-retest reliability, as well as its sensitivity to change in a longitudinal follow-up study.
METHODS: We assessed test-retest reliability of muscle MRE in 20 subjects with (n = 5) and without (n = 15) muscle diseases and compared this to Dixon proton density fat fraction (PDFF) and volume measurements. Next, we measured MRE muscle stiffness in 21 adults with Becker muscular dystrophy (BMD) and 21 age-matched healthy controls at baseline, and after 9 and 18 months. We compared two different methods of analysing MRE data in this study: \'Method A\' used the stiffness maps generated by the Philips MRE software, and \'Method B\' applied a custom-made procedure based on wavelength measurements on the MRE images.
RESULTS: Intraclass correlation coefficients (ICC) of muscle stiffness ranged from good (0.83 for left vastus medialis, P < 0.001) to poor (0.19 for right rectus femoris, P = 0.212) for the examined thigh muscles with Method A, but we did not find a significant test-retest reliability with Method B (P > 0.050 for all). The ICC of muscle PDFF and volume measurements was excellent (>0.90; P < 0.001) for all muscles. At baseline, the average stiffness of all thigh muscles was significantly lower in adults with BMD than in controls for both Method A (-0.2 kPa, P = 0.025) and Method B (-0.6 kPa, P < 0.001). Regardless of which method was used, there was no significant difference in the evolution of muscle stiffness in patients and controls over 18 months.
CONCLUSIONS: Test-retest reliability of muscle MRE using a simple 2D technique was suboptimal, and did not reliably measure muscle stiffness changes in adults with BMD as compared with controls over 18 months. While the results provide motivation for testing more advanced 3D MRE methods, we conclude that the simple 2D MRE implementation used in this study is not suitable as an outcome measure for characterizing thigh muscle in clinical trials.

BACKGROUND: Magnetic resonance elastography (MRE) is a rapidly developing medical imaging technique that allows for quantitative assessment of the biomechanical properties of the tissue. MRE is now regarded as the most accurate noninvasive test for detecting and staging liver fibrosis. A two-dimensional (2D MRE) acquisition version is currently deployed at >2000 locations worldwide. 2D MRE allows for the evaluation of the magnitude of the complex shear modulus, also referred to as stiffness. The development of 3D vector MRE has enabled researchers to assess the biomechanical properties of small organs where wave propagation cannot be adequately analyzed with the 2D MRE imaging approach used in the liver. In 3D vector MRE, the shear waves are imaged and processed throughout a 3D volume and processed with an algorithm that accounts for wave propagation in any direction. Additionally, the motion is also imaged in x, y, and z directions at each voxel, allowing for more advanced processing to be applied.
OBJECTIVE: This review describes the technical principles of 3D vector MRE, surveys its clinical applications in small organs, and discusses potential clinical significance of 3D vector MRE.
CONCLUSIONS: 3D vector MRE is a promising tool for characterizing the biomechanical properties of small organs such as the uterus, pancreas, thyroid, prostate, and salivary glands. However, its potential has not yet been fully explored.

BACKGROUND: Patients with Crohn\'s disease (CD) are at risk of progressing from inflammatory to stricturing and penetrating phenotypes. The influence of the depth of remission on the risk of progression has not been adequately evaluated.
METHODS: A retrospective cohort study including surgically naïve CD patients with inflammatory phenotype evaluated concomitantly by magnetic resonance enterography and colonoscopy. The degree of remission was correlated with the risk of progressing to stricturing and penetrating phenotypes.
RESULTS: Three hundred nineteen CD patients were included: 27.0% with transmural remission, 16.0% with isolated endoscopic remission, 14.4% with isolated radiologic remission, and 42.6% without remission. Patients with transmural remission presented the lowest rates of phenotype progression (1.2%), with a significant difference compared to isolated radiologic remission (10.9%, p = 0.019), to isolated endoscopic remission (19.6%, p ≤ 0.001), and to no remission (46.3%, p ≤ 0.001). In multivariate regression analysis, transmural remission (OR 0.017 95% CI 0.002-0.135, p < 0.001), isolated radiologic remission (OR 0.139 95% CI 0.049-0.396, p < 0.001), and isolated endoscopic remission (OR 0.301 95% CI 0.123-0.736, p = 0.008) resulted in lower rates of phenotype progression compared to no remission. No patient with transmural or isolated radiologic remission progressed to penetrating phenotypes.
CONCLUSIONS: The degree of bowel remission correlates with the risk of phenotype progression. Patients with transmural remission are at the lowest risk of progressing to stricturing and penetrating phenotypes.

Magnetic resonance elastography (MRE) and diffusion-weighted imaging (DWI) are complementary imaging techniques that detect disease based on viscoelasticity and water mobility, respectively. However, the relationship between viscoelasticity and water diffusion is still poorly understood, hindering the clinical translation of combined DWI-MRE markers. We used DWI-MRE to study 129 biomaterial samples including native and cross-linked collagen, glycosaminoglycans (GAGs) with different sulfation levels, and decellularized specimens of pancreas and liver, all with different proportions of solid tissue, or solid fractions. We developed a theoretical framework of the relationship between mechanical loss and tissue-water mobility based on two parameters, solid and fluid viscosity. These parameters revealed distinct DWI-MRE property clusters characterizing weak, moderate, and strong water-network interactions. Sparse networks interacting weakly with water, such as collagen or diluted decellularized tissue, resulted in marginal changes in water diffusion over increasing solid viscosity. In contrast, dense networks with larger solid fractions exhibited both free and hindered water diffusion depending on the polarity of the solid components. For example, polar and highly sulfated GAGs as well as native soft tissues hindered water diffusion despite relatively low solid viscosity. Our results suggest that two fundamental properties of tissue networks, solid fraction and network polarity, critically influence solid and fluid viscosity in biological tissues. Since clinical DWI and MRE are sensitive to these viscosity parameters, the framework we present here can be used to detect tissue remodeling and architectural changes in the setting of diagnostic imaging. STATEMENT OF SIGNIFICANCE: The viscoelastic properties of biological tissues provide a wealth of information on the vital state of cells and host matrix. Combined measurement of viscoelasticity and water diffusion by medical imaging is sensitive to tissue microarchitecture. However, the relationship between viscoelasticity and water diffusion is still poorly understood, hindering full exploitation of these properties as a combined clinical biomarker. Therefore, we analyzed the parameter space accessible by diffusion-weighted imaging (DWI) and magnetic resonance elastography (MRE) and developed a theoretical framework for the relationship between water mobility and mechanical parameters in biomaterials. Our theory of solid material properties related to particle motion can be translated to clinical radiology using clinically established MRE and DWI.

Crohn\'s disease (CD) poses significant morbidity, underscoring the need for effective, non-invasive inflammatory assessment using magnetic resonance enterography (MRE). This literature review evaluates recent publications on the role of deep learning in improving MRE for CD assessment. We searched MEDLINE/PUBMED for studies that reported the use of deep learning algorithms for assessment of CD activity. The study was conducted according to the PRISMA guidelines. The risk of bias was evaluated using the QUADAS-2 tool. Five eligible studies, encompassing 468 subjects, were identified. Our study suggests that diverse deep learning applications, including image quality enhancement, bowel segmentation for disease burden quantification, and 3D reconstruction for surgical planning are useful and promising for CD assessment. However, most of the studies are preliminary, retrospective studies, and have a high risk of bias in at least one category. Future research is needed to assess how deep learning can impact CD patient diagnostics, particularly when considering the increasing integration of such models into hospital systems.