Symptomatic Myeloma: PET, Whole-Body MR Imaging with Diffusion-Weighted Imaging or Both.

According to international guidelines, patients with suspected myeloma should primarily undergo low-dose whole-body computed tomography (CT) for diagnostic purposes. To optimize sensitivity and specificity and enable treatment response assessment, whole-body MR (WB-MR) imaging should include diffusion-weighted imaging with apparent diffusion coefficient maps and T1-weighted Dixon sequences with bone marrow Fat Fraction Quantification. At baseline WB-MR imaging shows greater sensitivity for the detecting focal lesions and diffuse bone marrow infiltration pattern than 18F-fluorodeoxyglucose PET-CT, which is considered of choice for evaluating response to treatment and minimal residual disease and imaging of extramedullary disease.

Multimodal surface coils for low field MR imaging.

Low field MRI is safer and more cost effective than the high field MRI. One of the inherent problems of low field MRI is its low signal-to-noise ratio or sensitivity. In this work, we introduce a multimodal surface coil technique for signal excitation and reception to improve the RF magnetic field (B1) efficiency and potentially improve MR sensitivity. The proposed multimodal surface coil consists of multiple identical resonators that are electromagnetically coupled to form a multimodal resonator. The field distribution of its lowest frequency mode is suitable for MR imaging applications. The prototype multimodal surface coils are built, and the performance is investigated and validated through numerical simulation, standard RF measurements and tests, and comparison with the conventional surface coil at low fields. Our results show that the B1 efficiency of the multimodal surface coil outperforms that of the conventional surface coil which is known to offer the highest B1 efficiency among all coil categories, i.e., volume coil, half-volume coil and surface coil. In addition, in low-field MRI, the required low-frequency coils often use large value capacitance to achieve the low resonant frequency which makes frequency tuning difficult. The proposed multimodal surface coil can be conveniently tuned to the required low frequency for low-field MRI with significantly reduced capacitance value, demonstrating excellent low-frequency operation capability over the conventional surface coil.

Mutli-modal straight flow matching for accelerated MR imaging.

Diffusion models have garnered great interest lately in Magnetic Resonance (MR) image reconstruction. A key component of generating high-quality samples from noise is iterative denoising for thousands of steps. However, the complexity of inference steps has limited its applications. To solve the challenge in obtaining high-quality reconstructed images with fewer inference steps and computational complexity, we introduce a novel straight flow matching, based on a neural ordinary differential equation (ODE) generative model. Our model creates a linear path between undersampled images and reconstructed images, which can be accurately simulated with a few Euler steps. Furthermore, we propose a multi-modal straight flow matching model, which uses relatively easily available modalities as supplementary information to guide the reconstruction of target modalities. We introduce the low frequency fusion layer and the high frequency fusion layer into our multi-modal model, which has been proved to produce promising results in fusion tasks. The proposed multi-modal straight flow matching (MMSflow) achieves state-of-the-art performances in task of reconstruction in fastMRI and Brats-2020 and improves the sampling rate by an order of magnitude than other methods based on stochastic differential equations (SDE).

Potential Application of Hydrops MR Imaging: A Systematic Review.

BACKGROUND: Diagnostic dilemma between clinical Meniere's disease and radiological endolymphatic hydrops (EH) has emerged since the introduction of hydrops magnetic resonance imaging (MRI). The aim of this study is to explore the potential application of hydrops MRI on diagnosing the EH. METHODS: This review was developed from peer-reviewed articles published in those journals listed on journal of citation reports. The MEDLINE database of the US National Library of Medicine, Scopus, and Google Scholar were used to collect articles based on the guidelines (PRISMA 2020 statement) for reporting reviews. RESULTS: Initially, 470 articles were retrieved from 1983 to 2023, and 80 relevant articles were ultimately selected. The sensitivity (69%-92%) and specificity (78%-96%) values varied from each laboratory for detecting EH via hydrops MRI, probably due to candidate selection and the grading system employed. CONCLUSION: The application of hydrops MRI allows (1) differentiation between EH and sudden sensorineural hearing loss; (2) determination of the affected side of EH; and (3) confirmation of the diagnosis of EH concomitant with other disorders. Notably, not all differentials for EH can be visualized on MR images. One of the existing gaps to be filled is that updated hydrops MRI fails to identify distortion, that is, rupture, collapse, fistula, or fibrosis of the inner ear compartments, akin to what histopathological evidence can demonstrate. Hence, enhanced ultrahigh resolution of hydrops MRI is required for demonstrating fine structures of the inner ear compartments in the future.

Imaging and Downstaging Bladder Cancer with the 177Lu-Labeled Bioorthogonal Nanoprobe.

Efforts on bladder cancer treatment have been shifting from extensive surgery to organ preservation in the past decade. To this end, we herein develop a multifunctional nanoagent for bladder cancer downstaging and bladder-preserving therapy by integrating mucosa penetration, reduced off-target effects, and internal irradiation therapy into a nanodrug. Specifically, an iron oxide nanoparticle was used as a carrier that was coated with hyaluronic acid (HA) for facilitating mucosa penetration. Dibenzocyclooctyne (DBCO) was introduced into the HA coating layer to react through bioorthogonal reaction with azide as an artificial receptor of bladder cancer cells, to improve the cellular internalization of the nanoprobe labeled with 177Lu. Through magnetic resonance imaging, the targeted imaging of both nonmuscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC) was realized after intravesical instillation of the multifunctional probe, both NMIBC and MIBC were found downstaged, and the metastasis was inhibited, which demonstrates the potential of the multifunctional nanoprobe for bladder preservation in bladder cancer treatment.

Advances in Fetal Brain Imaging.

Over the last 20 years, there have been remarkable developments in fetal brain MR imaging analysis methods. This article delves into the specifics of structural imaging, diffusion imaging, functional MR imaging, and spectroscopy, highlighting the latest advancements in motion correction, fetal brain development atlases, and the challenges and innovations. Furthermore, this article explores the clinical applications of these advanced imaging techniques in comprehending and diagnosing fetal brain development and abnormalities.

New Imaging Markers in Multiple Sclerosis and Related Disorders: Smoldering Inflammation and the Central Vein Sign.

Concepts of multiple sclerosis (MS) biology continue to evolve, with observations such as "progression independent of disease activity" challenging traditional phenotypic categorization. Iron-sensitive, susceptibility-based imaging techniques are emerging as highly translatable MR imaging sequences that allow for visualization of at least 2 clinically useful biomarkers: the central vein sign and the paramagnetic rim lesion (PRL). Both biomarkers demonstrate high specificity in the discrimination of MS from other mimics and can be seen at 1.5 T and 3 T field strengths. Additionally, PRLs represent a subset of chronic active lesions engaged in "smoldering" compartmentalized inflammation behind an intact blood-brain barrier.

Prenatal Imaging of Supratentorial Fetal Brain Malformation.

This review article provides a comprehensive overview of fetal MR imaging in supratentorial cerebral malformations. It emphasizes the importance of fetal MR imaging as an adjunct diagnostic tool used alongside ultrasound, improving the detection and characterization of prenatal brain abnormalities. This article reviews a spectrum of cerebral malformations, their MR imaging features, and the clinical implications of these findings. Additionally, it outlines the growing importance of fetal MR imaging in the context of perinatal care.

3 Tesla Fetal MR Imaging Quality and Safety Considerations.

Medical imaging, particularly fetal MR imaging, has undergone a transformative shift with the introduction of 3 Tesla (3T) clinical MR imaging systems. The utilization of higher static magnetic fields in these systems has resulted in remarkable advancements, including superior soft tissue contrast, improved spatial and temporal resolution, and reduced image acquisition time. Despite these notable benefits, safety concerns have emerged, stemming from the elevated static magnetic field strength, amplified acoustic noise, and increased radiofrequency power deposition. This article provides an overview of fetal MR imaging at 3T, its benefits and drawbacks, and the potential safety issues.

MR Imaging of the Fetal Gastrointestinal Anomalies.

Fetal MR imaging has been shown to be a useful tool for the diagnosis of fetal gastro-intestinal pathologies. To recognize the various pathologies, it is, however, essential to know the normal MR imaging appearance of the fetal bowel at various gestational ages. By providing additional information to ultrasound in case of a fetal gastrointestinal anomaly, MR imaging helps to improve planning for the delivery, postnatal management, and improves parental counseling.

How to Perform Fetal MR Imaging.

This article provides the readers with practical guidance on how to perform fetal MR imaging, including technical considerations such as scanner field strength and use of appropriate radiofrequency receive coils, and summarizes the role, strengths, and limitations of the various MR imaging sequences. The authors review the various factors to consider in scan preparation, including study indication, timing, maternal preparation, and the creation of an institutional fetal imaging protocol. Additional factors that go into scan optimization during acquisition including prioritizing maternal comfort and ways to troubleshoot various artifacts that maybe encountered in fetal imaging are discussed.

Fetal Cardiovascular MR Imaging.

Prenatal diagnosis of congenital heart disease allows for appropriate planning of delivery and an opportunity to inform families about the prognosis of the cardiac malformation. On occasion, prenatal therapies may be offered to improve perinatal outcomes. While ultrasound is the primary diagnostic method, advances have led to interest in fetal MRI for its potential to aid in clinical decision-making. This review explores technical innovations and the clinical utility of fetal cardiovascular magnetic resonance (CMR), highlighting its role in diagnosing and planning interventions for complex heart conditions. Future directions include the prediction of perinatal physiology and guidance of delivery planning.

Right Ventricular Strain Derived from Cardiac MRI Feature Tracking for the Diagnosis and Prognosis of Arrhythmogenic Right Ventricular Cardiomyopathy.

Purpose To demonstrate the myocardial strain characteristics of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), based on revised Task Force Criteria (rTFC), and to explore the prognostic value of strain analysis in ARVC. Materials and Methods This retrospective study included 247 patients (median age, 38 years [IQR, 28-48 years]; 167 male, 80 female) diagnosed with ARVC, based on rTFC, between 2014 and 2018. Patients were divided into "possible" (n =25), "borderline" (n = 40), and "definite" (n = 182) ARVC groups following rTFC. Biventricular global strain parameters were calculated using cardiac MRI feature tracking (FT). The primary outcome was defined as a composite of cardiovascular events, including cardiovascular death, heart transplantation, and appropriate implantable cardioverter defibrillator discharge. Univariable and multivariable cumulative logistic regression and Cox proportional hazards regression analysis were used to evaluate the diagnostic and prognostic value of right ventricle (RV) strain parameters. Results Patients with definite ARVC had significantly reduced RV global strain in all three directions compared with possible or borderline groups (all P < .001). RV global longitudinal strain (GLS) was an independent predictor for disease (odds ratio, 1.09 [95% CI: 1.02, 1.16]; P = .009). During a median follow-up of 3.4 years (IQR, 2.0-4.9 years), 55 patients developed primary end point events. Multivariable analysis showed that RV GLS was independently associated with the occurrence of cardiovascular events (hazard ratio, 1.15 [95% CI: 1.07, 1.24]; P < .001). Kaplan-Meier analysis showed that patients with RV GLS worse than median had a higher risk of combined cardiovascular events (log-rank P < .001). Conclusion RV GLS derived from cardiac MRI FT demonstrated good diagnostic and prognostic value in ARVC. Keywords: MR Imaging, Image Postprocessing, Cardiac, Right Ventricle, Cardiomyopathies, Arrhythmogenic Right Ventricular Cardiomyopathy, Revised Task Force Criteria, Cardiovascular MR, Feature Tracking, Cardiovascular Events Supplemental material is available for this article. © RSNA, 2024.

Arrhythmic Mitral Valve Prolapse Phenotype: An Unsupervised Machine Learning Analysis Using a Multicenter Cardiac MRI Registry.

Purpose To use unsupervised machine learning to identify phenotypic clusters with increased risk of arrhythmic mitral valve prolapse (MVP). Materials and Methods This retrospective study included patients with MVP without hemodynamically significant mitral regurgitation or left ventricular (LV) dysfunction undergoing late gadolinium enhancement (LGE) cardiac MRI between October 2007 and June 2020 in 15 European tertiary centers. The study end point was a composite of sustained ventricular tachycardia, (aborted) sudden cardiac death, or unexplained syncope. Unsupervised data-driven hierarchical k-mean algorithm was utilized to identify phenotypic clusters. The association between clusters and the study end point was assessed by Cox proportional hazards model. Results A total of 474 patients (mean age, 47 years ± 16 [SD]; 244 female, 230 male) with two phenotypic clusters were identified. Patients in cluster 2 (199 of 474, 42%) had more severe mitral valve degeneration (ie, bileaflet MVP and leaflet displacement), left and right heart chamber remodeling, and myocardial fibrosis as assessed with LGE cardiac MRI than those in cluster 1. Demographic and clinical features (ie, symptoms, arrhythmias at Holter monitoring) had negligible contribution in differentiating the two clusters. Compared with cluster 1, the risk of developing the study end point over a median follow-up of 39 months was significantly higher in cluster 2 patients (hazard ratio: 3.79 [95% CI: 1.19, 12.12], P = .02) after adjustment for LGE extent. Conclusion Among patients with MVP without significant mitral regurgitation or LV dysfunction, unsupervised machine learning enabled the identification of two phenotypic clusters with distinct arrhythmic outcomes based primarily on cardiac MRI features. These results encourage the use of in-depth imaging-based phenotyping for implementing arrhythmic risk prediction in MVP. Keywords: MR Imaging, Cardiac, Cardiac MRI, Mitral Valve Prolapse, Cluster Analysis, Ventricular Arrhythmia, Sudden Cardiac Death, Unsupervised Machine Learning Supplemental material is available for this article. © RSNA, 2024.

Diagnostic Value of 3.0 T Magnetic Resonance Imaging in Active Crohn's Disease.

BACKGROUND: Magnetic resonance enteroclysis (MRE) has been widely applied to diagnose Crohn's disease (CD). Magnetic resonance (MR) at 3.0 T improves signal-to-noise ratio (SNR), shortens image acquisition time, and shows more advantages. OBJECTIVE: This study aimed to retrospectively analyze the diagnostic value of 3.0 T MR imaging for active CD. METHODS: 48 CD patients hospitalized in our hospital from January 2021 to December 2022 were selected as the study subjects. These 48 CD patients underwent both double-balloon enteroscopy and 3.0 T MRE. All patients' arterial phase signal, venous phase signal, bowel wall, and bowel lumen of MRE were observed to identify whether they suffered from active CD. Based on the results of enteroscopy, the number of true positives, true negatives, false negatives, and false positives diagnosed by MRE were screened; next, the diagnostic accuracy, sensitivity, and specificity of MRE in assessing active CD were calculated. RESULTS: Of the 48 patients, 39 were diagnosed with small bowel CD by MRE, which was not significantly different from the results of enteroscopy (P>0.05). According to MRE diagnostic results, the arterial phase predominantly presented high signal intensity, and the venous phase mainly presented low signal intensity or isointensity. Small bowel CD lesions were primarily characterized by bowel wall thickening, rare pneumatosis enhancement of the bowel wall, bowel lumen pneumatosis or dilatation, and rare strictures. Besides, MRE presented an accuracy of 93.75%, sensitivity of 97.37%, and specificity of 80.00% in diagnosing CD. CONCLUSION: 3.0 T MR imaging has diagnostic value for active CD and shows certain clinical application value.

Mean Apparent Propagator MRI: Quantitative Assessment of Tumor-Stroma Ratio in Invasive Ductal Breast Carcinoma.

Purpose To determine whether metrics from mean apparent propagator (MAP) MRI perform better than apparent diffusion coefficient (ADC) value in assessing the tumor-stroma ratio (TSR) status in breast carcinoma. Materials and Methods From August 2021 to October 2022, 271 participants were prospectively enrolled (ClinicalTrials.gov identifier: NCT05159323) and underwent breast diffusion spectral imaging and diffusion-weighted imaging. MAP MRI metrics and ADC were derived from the diffusion MRI data. All participants were divided into high-TSR (stromal component < 50%) and low-TSR (stromal component ≥ 50%) groups based on pathologic examination. Clinicopathologic characteristics were collected, and MRI findings were assessed. Logistic regression was used to determine the independent variables for distinguishing TSR status. The area under the receiver operating characteristic curve (AUC) and sensitivity, specificity, and accuracy were compared between the MAP MRI metrics, either alone or combined with clinicopathologic characteristics, and ADC, using the DeLong and McNemar test. Results A total of 181 female participants (mean age, 49 years ± 10 [SD]) were included. All diffusion MRI metrics differed between the high-TSR and low-TSR groups (P < .001 to P = .01). Radial non-Gaussianity from MAP MRI and lymphovascular invasion were significant independent variables for discriminating the two groups, with a higher AUC (0.81 [95% CI: 0.74, 0.87] vs 0.61 [95% CI: 0.53, 0.68], P < .001) and accuracy (138 of 181 [76%] vs 106 of 181 [59%], P < .001) than that of the ADC. Conclusion MAP MRI may serve as a better approach than conventional diffusion-weighted imaging in evaluating the TSR of breast carcinoma. Keywords: MR Diffusion-weighted Imaging, MR Imaging, Breast, Oncology ClinicalTrials.gov Identifier: NCT05159323 Supplemental material is available for this article. © RSNA, 2024.

Longitudinal Assessment of Glymphatic Changes Following Mild Traumatic Brain Injury: Insights from PVS burden and DTI-ALPS Imaging.

Traumatic brain injury (TBI) even in the mild form may result in long-lasting post-concussion symptoms. TBI is also a known risk to late-life neurodegeneration. Recent studies suggest that dysfunction in the glymphatic system, responsible for clearing protein waste from the brain, may play a pivotal role in the development of dementia following TBI. Given the diverse nature of TBI, longitudinal investigations are essential to comprehending the dynamic changes in the glymphatic system and its implications for recovery. In this prospective study, we evaluated two promising glymphatic imaging markers, namely the enlarged perivascular space (ePVS) burden and Diffusion Tensor Imaging-based ALPS index, in 44 patients with mTBI at two early post-injury time points: approximately 14 days (14Day) and 6-12 months (6-12Mon) post-injury, while also examining their associations with post-concussion symptoms. Additionally, 37 controls, comprising both orthopedic patients and healthy individuals, were included for comparative analysis. Our key findings include: 1) White matter ePVS burden (WM-ePVS) and ALPS index exhibit significant correlations with age. 2) Elevated WM-ePVS burden in acute mTBI (14Day) is significantly linked to a higher number of post-concussion symptoms, particularly memory problems. 3) The increase in the ALPS index from acute (14Day) to the chronic (6-12Mon) phases in mTBI patients correlates with improvement in sleep measures. Furthermore, incorporating WM-ePVS burden and the ALPS index from acute phase enhances the prediction of chronic memory problems beyond socio-demographic and basic clinical information, highlighting their distinct roles in assessing glymphatic structure and activity. Early evaluation of glymphatic function could be crucial for understanding TBI recovery and developing targeted interventions to improve patient outcomes.

Soft tissue vascular tumor-like lesions in adults: imaging and pathological analysis pitfalls per ISSVA classification.

OBJECTIVES: To compare the magnetic resonance imaging (MRI) and Doppler ultrasound (DUS) findings with the pathological findings of soft tissue vascular tumors (STVTs) according to the 2018 ISSVA (International Society for the Study of Vascular Anomalies) classification to differentiate vascular tumors from vascular malformations. METHODS: This retrospective study included patients with STVTs who underwent contrast-enhanced MRI and pathological analysis at our hospital between 2010 and 2020. The presumptive diagnosis based on the on-site imaging and histological analysis was compared with imaging and histological analysis conducted off-site utilizing the ISSVA criteria. RESULTS: This study included 31 patients with 31 vascular tumors located in the head and neck (n = 3), trunk (n = 2), and extremities (n = 26). The off-site pathological analysis confirmed benign vascular tumors in 54.8% of cases (non-involuting congenital hemangioma: 35.5%; epithelioid hemangioma: 13%; pyogenic granuloma: 3%; and spindle cell hemangioma: 3%). Based on the off-site histological analysis, 25.8% were reclassified as having a vascular malformation whereas three had other benign lesions. Only phleboliths were associated with a vascular malformation (p = 0.03). The concordance between off-site MRI and pathological findings was fair (k = 0.3902 (0.0531-0.7274)), whereas that between on-site and off-site pathological analyses was poor (k = -0.0949 (-0.4661 to 0.2763)). CONCLUSION: Benign vascular tumors have non-specific imaging features on imaging with some overlap with atypical vascular malformations. Therefore, histological analysis is recommended. Imaging and pathological analyses should be performed in accordance with the ISSVA classification to minimize inter-observer discrepancies. CRITICAL RELEVANCE STATEMENT: Imaging features of benign vascular tumors on MRI are non-specific, leading to discrepancies with pathological findings and potential overlap with atypical vascular malformations. Imaging and histological analyses should be performed in accordance with ISSVA guidelines to improve patient management. KEY POINTS: The imaging features of benign vascular tumors are non-specific. Histological analysis is recommended for soft tissue vascular tumors in adults. Analyses of soft tissue vascular tumors should be performed in accordance with ISSVA guidelines.

[Analysis of intracranial saccular aneurysm wall: neuroimaging and histopathological correlates]. / Issledovanie stenki intrakranial'nykh meshotchatykh anevrizm: neirovizualizatsionnye i gistopatologicheskie korrelyaty.

BACKGROUND: Contrast enhancement of intracranial aneurysm wall during MRI with targeted visualization of vascular wall correlates with previous aneurysm rupture and, according to some data, may be a predictor of further rupture of unruptured aneurysms. OBJECTIVE: To analyze possible causes of aneurysm contrast enhancement considering morphological data of aneurysm walls. MATERIAL AND METHODS: The study included 44 patients with intracranial aneurysms who underwent preoperative MRI between November 2020 and September 2022. Each aneurysm was assessed regarding contrast enhancement pattern. Microsurgical treatment of aneurysm was accompanied by resection of its wall for subsequent histological and immunohistochemical analysis regarding thrombosis, inflammation and neovascularization. Specimens were subjected to histological and immunochemical analysis. Immunohistochemical analysis was valuable to estimate inflammatory markers CD68 and CD3, as well as neurovascularization marker SD31. RESULTS: Aneurysms with contrast-enhanced walls were characterized by higher number of CD3+, CD68+, CD31+ cells and parietal clots. Intensity of contrast enhancement correlated with aneurysm wall abnormalities. CONCLUSION: Contrast enhancement of aneurysm wall can characterize various morphological abnormalities.

Advanced Brain Imaging in Central Nervous System Demyelinating Diseases.

In recent decades, advances in neuroimaging have profoundly transformed our comprehension of central nervous system demyelinating diseases. Remarkable technological progress has enabled the integration of cutting-edge acquisition and postprocessing techniques, proving instrumental in characterizing subtle focal changes, diffuse microstructural alterations, and macroscopic pathologic processes. This review delves into state-of-the-art modalities applied to multiple sclerosis, neuromyelitis optica spectrum disorders, and myelin oligodendrocyte glycoprotein antibody-associated disease. Furthermore, it explores how this dynamic landscape holds significant promise for the development of effective and personalized clinical management strategies, encompassing support for differential diagnosis, prognosis, monitoring treatment response, and patient stratification.