Recovery Sequences Research Articles

Diagnostics and classification of fractures of the thoracic and lumbar spine in adults : Approach depending on the bone structure

The epidemiology, treatment and prognosis of thoracolumbar vertebral fractures are fundamentally influenced by the bone quality of the patient. In individuals with healthy bone structure, ahigh-energy trauma is typically required to cause afracture. In contrast, osteoporosis can cause fractures and also be present as acomorbid pathology in traumatic fractures. Comprehensive diagnostics and a precise classification are essential for appropriate treatment. This narrative review outlines the diagnostic approach and classification of thoracolumbar vertebral fractures depending on the bone quality as the basis of treatment. In addition to aphysical examination, conventional radiographs with the patient in a standing position and computed tomography (CT) scans of the affected region serve as the foundation for fracture classification. Supplementary magnetic resonance imaging (MRI) primarily assesses discoligamentous and neurological structures of the spine as well as the age of the fracture. In suspected cases of osteoporotic fractures, ashort-tau inversion recovery (STIR) sequence of the entire thoracic and lumbar spine is recommended for reliable detection of bone marrow edema. For patients with healthy bone structure, the AOSpine classification is used, whereas the osteoporotic fracture (OF) classification and the OF score are applied in cases of osteoporosis.

3D printing of the brachial plexus and its osseous landmarks using magnetic resonance neurography for thoracic outlet syndrome evaluation.

Patient-specific three-dimensional (3D) printed anatomic models are valuable clinical tools that facilitate enhanced visualization of pertinent anatomic structures and have demonstrated benefits of reduced surgical times, increased surgeon confidence, and improved operative results and subsequent patient outcomes. Medical image-based 3D printed anatomic models are generally created from computed tomography (CT), however magnetic resonance imaging (MRI), which offers exquisite soft tissue characterization and flexible contrast avoiding the use of ionizing radiation, is an attractive alternative. Herein, the application of 3D printing incorporating both MR neurography and zero-echo time (ZTE) MRI for visualization of the brachial plexus anatomy in a subject with thoracic outlet syndrome (TOS) is described. A 28-year-old man presented with chronic right upper limb discomfort and paresthesias extending from the shoulder region to the third and fourth digits. The subject underwent evaluation with a unilateral brachial plexus MR neurography protocol at 3.0 Tesla for suspicion of TOS. The protocol included T2-weighted, 3D fast spin echo short-tau inversion recovery (STIR-FSE) and 3D radial ZTE sequences for depiction of the nerves and bones, respectively. The first rib and its synostosis impinged upon the inferior aspect of the T1 nerve root (T1NR), with accompanying mild enlargement of the T1NR. A 3D printed anatomic model was created and included: (1) bone (spine, ribs, clavicle, scapula, and humerus), (2) brachial plexus, and (3) costal cartilage. The 3D printed model clearly demonstrated a T1NR impingement from the synostosis, confirming the diagnosis of neurologic thoracic outlet syndrome (TOS) and guided the treatment approach in prescribing TOS-specific physical therapy, which led to significant improvements in the patient's condition. To our knowledge, this is the first in-vivo human 3D printed case for TOS using MRI-only data. The 3D printed model allowed for improved visualization and understanding of the spatial relationships between the nerves of the brachial plexus and surrounding osseous structures responsible for the patient's symptoms. Not applicable.

Bright middle cerebellar peduncle sign in multiple system atrophy with predominant cerebellar ataxia is more apparent in double-inversion recovery imaging than in conventional imaging.

Multiple system atrophy (MSA) is a neurodegenerative disorder that presents as parkinsonism, cerebellar ataxia, and autonomic dysfunction. Magnetic resonance imaging (MRI) findings of MSA are reported to be the atrophy of the putamen/pons/cerebellum, hot cross bun sign, and bright middle cerebellar peduncle (MCP) sign. Here, we assessed the sensitivity of detecting the bright MCP sign in patients with MSA cerebellar variant (MSA-C) using a double inversion recovery (DIR) procedure, comparing it to the sensitivity of detection by T2-weighted image (T2WI) and fluid-attenuated inversion recovery (FLAIR) sequences on conventional MRI. We evaluated 6 MSA-C patients and 6 control patients (multiple sclerosis, neuromyelitis optica, and spinocerebellar atrophy). Characteristics of all the patients were collected, and MRI was analyzed. Two neurologists independently evaluated the visualization of the bright MCP sign using a 4-point visual grade from Grade 0 to Grade 3. Differences in grade between DIR and T2WI or FLAIR were statistically analyzed. Also, as a quantitative analysis, the signal intensity of the MCP lesion was compared with that of the ipsilateral thalamus, and the MCP/thalamus ratio was evaluated. As a result, DIR more sensitively showed the bright MCP signs of MSA-C patients than T2WI or FLAIR. Also, the bright MCP sign deteriorated and expanded over time in the cases we followed with MRI. We also evaluated hot cross bun sign in the pons, but the hot cross bun sign in MSA-C patients was not significantly different between the DIR and conventional MRI sequences. The DIR procedure can be a more sensitive method for detecting the involvement of MCP lesions in MSA-C.

Abstract Su902: Ability of Composite Magnetic Resonance Brain Imaging Scores to Predict Functional Outcomes in Survivors of Cardiac Arrest

Background: Brain magnetic resonance imaging (MRI) has been examined for neuroprognostication (NP) after out-of-hospital cardiac arrest (OHCA). However, studies have focused on predicting poor outcomes of non-awakening and/or death. Recommendations for utilization of brain MRI in NP remain weak due to its subjective interpretation. Aim: We modified a previously published brain MRI score and examined our quantitated NP scores’ ability to predict good functional outcomes in OHCA survivors. Methods: We screened OHCA cases (2017-2023, Seattle Medic One registry) for patients who survived to hospital discharge and had brain MRIs performed 25 hours-7 days after arrest. Each MRI was reviewed by two adjudicators; a third reviewer served as tie-breaker. Reviewers were blinded to patient outcomes. Diffusion Weighted Imaging and Fluid Attenuated Inversion Recovery sequences were reviewed to score 35 neuroanatomical regions. Graded severity for estimated affected area (0 = zero; 1= < 25%; 2 = 25-50%; 3 = 50-75%; 4 = >75%) and binary (0 = not affected, 1 = affected) scores were tallied. Points were summed for a composite brain MRI score, “ NP score ”, possible range 0-214. Primary outcome was Cerebral Performance Categories (CPC) at hospital discharge (1-2: “independent”, 3: “dependent”, 4: “vegetative state”). Computational modeling employed folded normal distributions and Maximum Likelihood Estimation. Statistical analyses were Pearson’s, Spearman’s, ANOVA, Fisher LSD, t-tests. Results: Forty-two (42) adult patients were included (74% men, 55% Caucasian). Median NP score was 11.5 (IQR 41.5, n=42) overall, 2 (IQR=10, n=21) for independent versus 25.5 (IQR 36.5, n=10) for dependent patients, and 92 (IQR=81, n=11) for those in a vegetative state. NP scores strongly correlated with CPC [ r s (40) = .69, p< .001 ], and were significantly different between CPC groups [F(2,39) = 32.66, p< 0.001 ]. Interrater concordance for NP score was high (Pearson) r = .88 [r = .96; .95; .90; .71]. Conclusions: Our NP score correlated well with good functional outcomes in OHCA survivors, and (1) identified distinct thresholds that well-separate functional outcome groups and (2) had very strong concordance rate among four pairs of adjudicators. NP score-based predictive modeling differentiates functional outcomes beyond good versus poor dichotomy and may help providers and family anticipate recovery potential.

Clazosentan-induced reversible focal brain edema in basal ganglia following aneurysmal subarachnoid hemorrhage treatment: illustrative case.

Clazosentan, a selective endothelin A receptor antagonist, effectively prevents cerebral vasospasm following aneurysmal subarachnoid hemorrhage. Although various adverse effects have been reported, there have been no specific case reports of clazosentan-associated focal brain edema. This report highlights a rare complication associated with clazosentan treatment. A female in her 70s with a subarachnoid hemorrhage underwent surgical clipping of a ruptured middle cerebral artery aneurysm and received clazosentan postoperatively. Six days after surgery, magnetic resonance imaging revealed high-intensity signals in the left basal ganglia on fluid-attenuated inversion recovery and apparent diffusion coefficient sequences without changes on diffusion-weighted imaging. The patient's right-sided hemiparesis and disturbance of consciousness gradually progressed. On day 9, clazosentan was discontinued because of suspected adverse effects. Within approximately 2 weeks of discontinuation, both imaging findings and neurological symptoms improved. The temporal relationship between clazosentan administration, symptom onset, and improvement after discontinuation strongly suggested clazosentan-induced vasogenic edema. Clazosentan can cause reversible localized vasogenic brain edema in the basal ganglia following subarachnoid hemorrhage treatment. This rare but significant complication underscores the importance of careful neurological monitoring and timely imaging in patients receiving clazosentan. Further research is required to understand the risk factors and mechanisms underlying this phenomenon. https://thejns.org/doi/10.3171/CASE24567.

Radiofrequency ablation guided by real-time cardiovascular magnetic resonance.

Cardiovascular magnetic resonance (CMR) is gaining ground in guiding electrophysiology (EP)-based ablation procedures of typical atrial flutter and atrial fibrillation, allowing for the avoidance of radiation exposure for patients and operators and reducing the risk of occupational illnesses. CMR allows comprehensive assessment of cardiac anatomy and provides tissue characterization by identifying pathological substrates, such as myocardial scars and edema, identified with the implementation of late gadolinium enhancement and T2-weighted short-tau inversion recovery sequences. Intraprocedural imaging is useful for real-time catheter tracking during the ablation procedure while simultaneously providing visualization of cardiac anatomy. Additionally, CMR facilitates the evaluation of the ablation procedure accuracy by acquiring edema-sensitive sequences, thereby aiding in preventing early complications. This report serves as a primer for radiologists and illustrates the value of CMR in planning and performing the ablation procedure, as well as its role in post-procedural imaging.

MRI features of primary lower extremity lymphedema: a retrospective analysis of 228 patients

BackgroundThe value of MRI presentation of primary lower extremity lymphedema in assessing the severity of lower extremity lymphedema is uncertain. The purpose of this study was to assess the role of MRI presentation in staging primary lower extremity lymphedema. Methods228 patients with clinically diagnosed primary lower limb lymphoedema from January 2018 to December 2019 in our hospital were enrolled retrospectively. Patients were divided into stages I, II, and III based on the 2020 International Society of Lymphology (ISL) clinical staging standards. Two radiologists assessed the following characteristics of the Short Term Inversion Recovery (STIR) sequence: the extent of edema (longitudinally and transversely), the frequency of MRI manifestations, including the presence of dermal thickening, and the morphology of edema (grid, honeycomb, parallel-lines, banded, crescent, and lymphatic lake). The Kappa test was used to assess interobserver agreement. The chi-square test was used to compare the frequency differences of MRI manifestations between different clinical stages. The Spearman test evaluated the correlation between edema extent and clinical stage. ResultsThe extent of edema was positively correlated with clinical stage, both longitudinally and transversely. When comparing stages, the incidence of dermal thickening in stages II and III was significantly higher than in stage I. The incidence of parallel-lines in stage I was significantly higher than that in stages II and III. The grid and banded sign incidence in stages I and II were significantly higher than in stage III. The incidence of honeycomb in stages II and III was significantly higher than in stage I. The incidence of lymphatic lake and crescent in stage III was significantly higher than in stages I and II (P<0.001). ConclusionSTIR can sensitively diagnose lymphedema and assist in clinical staging. MRI manifestations of primary lower extremity lymphedema in different stages have specific MRI features.

Deep medullary vein abnormalities impact white matter hyperintensity volume through increases in interstitial free water

BackgroundOur intent was to explore the mediating role of interstitial free water (FW) linking deep medullary vein (DMV) score to white matter hyperintensity (WMH) volume.MethodsOur research team conducted a forward-looking analysis of initial clinical and imaging information gathered from 125 patients with cerebral small vessel disease. We identified six anatomic DMV regions on susceptibility weighted imaging (SWI) studies. Each region earned a score of 0–3, determined by the visual conditions of vessels, summing all six to generate a DMV score. We utilized fluid-attenuated inversion recovery (FLAIR) sequences to measure the volume of WMH. Additionally, we employed diffusion tensor imaging (DTI) to assess FW value.ResultsDMV score significantly positively correlated with FW value and with WMH volume (p < 0.05), and value of FW positively correlated with WMH volume (p < 0.05). The indirect effect of DMV score on WMH volume was mediated by FW (β = 0.281, 95% confidence interval [CI]: 0.178–0.388), whether adjusted for age and gender (β = 0.142, 95% CI: 0.058–0.240) or for age, gender and vascular risk factors (β = 0.141, 95% CI: 0.054–0.249).ConclusionDMV score correlate with WMH volume by virtue of FW increases in white matter.

A predictive model for survival outcomes of glioma patients based on multi-parametric, multi-regional MRI radiomics features and clinical features

To establish a predictive model for survival outcomes of glioma patients based on both brain radiomics features from preoperative MRI multi-sequence images and clinical features. We retrospectively analyzed the MRI images and clinical data of 388 glioma patients and extracted the radiomics features from the peritumoral edema zone, tumor core, and whole tumor on T1, T2, and T1-weighted contrast-enhanced (T1CE) and fluid attenuated inversion recovery (FLAIR) sequences. The cases were divided into a training set (271 cases) and a test set (117 cases). Random survival forest algorithms were used to select the radiomics features associated with overall survival (OS) in the training set to construct a radiomic score (Rad-score), based on which the patients were classified into high- and low-risk groups for Kaplan-Meier survival analysis. Cox proportional hazard regression models for the 3 different tumor zones were constructed, and their performance for predicting 1- and 3-year survival rates was evaluated using 5-fold cross-validation and AUC analysis followed by external validation using data from another 10 glioma patients. The best-performing model was used for constructing a nomogram for survival predictions. Five radiomics features from the tumor core, 7 from the peritumoral edema zone, and 5 from the whole tumor were selected. In both the training and test sets, the high- and low-risk groups had significantly different OS (P < 0.05), and age, IDH status and Rad-score were independent factors affecting OS. The combined model showed better performance than the Rad-score model with AUCs for 1-year and 3-year survival prediction of 0.750 and 0.778 in the training set, 0.764 and 0.800 in the test set, and 0.938 and 0.917 in external validation, respectively. The predictive model combining preoperative multi-modal MRI radiomics features and clinical features can effectively predict survival outcomes of glioma patients.

Free-breathing 3D cardiac extracellular volume (ECV) mapping using a linear tangent space alignment (LTSA) model.

To develop a new method for free-breathing 3D extracellular volume (ECV) mapping of the whole heart at 3 T. A free-breathing 3D cardiac ECV mapping method was developed at 3 T. T1 mapping was performed before and after contrast agent injection using a free-breathing electrocardiogram-gated inversion recovery sequence with spoiled gradient echo readout. A linear tangent space alignment model-based method was used to reconstruct high-frame-rate dynamic images from (k,t)-space data sparsely sampled along a random stack-of-stars trajectory. Joint T1 and transmit B1 estimation were performed voxel-by-voxel for pre- and post-contrast T1 mapping. To account for the time-varying T1 after contrast agent injection, a linearly time-varying T1 model was introduced for post-contrast T1 mapping. ECV maps were generated by aligning pre- and post-contrast T1 maps through affine transformation. The feasibility of the proposed method was demonstrated using in vivo studies with six healthy volunteers at 3 T. We obtained 3D ECV maps at a spatial resolution of 1.9 × 1.9 × 4.5 mm3 and a FOV of 308 × 308 × 144 mm3, with a scan time of 10.1 ± 1.4 and 10.6 ± 1.6 min before and after contrast agent injection, respectively. The ECV maps and the pre- and post-contrast T1 maps obtained by the proposed method were in good agreement with the 2D MOLLI method both qualitatively and quantitatively. The proposed method allows for free-breathing 3D ECV mapping of the whole heart within a practically feasible imaging time. The estimated ECV values from the proposed method were comparable to those from the existing method.

Parasagittal dural volume correlates with cerebrospinal fluid volume and developmental delay in children with autism spectrum disorder

BackgroundThe parasagittal dura, a tissue that lines the walls of the superior sagittal sinus, acts as an active site for immune-surveillance, promotes the reabsorption of cerebrospinal fluid, and facilitates the removal of metabolic waste products from the brain. Cerebrospinal fluid is important for the distribution of growth factors that signal immature neurons to proliferate and migrate. Autism spectrum disorder is characterized by altered cerebrospinal fluid dynamics.MethodsIn this retrospective study, we investigated potential correlations between parasagittal dura volume, brain structure volumes, and clinical severity scales in young children with autism spectrum disorder. We employed a semi-supervised two step pipeline to extract parasagittal dura volume from 3D-T2 Fluid Attenuated Inversion Recovery sequences, based on U-Net followed by manual refinement of the extracted parasagittal dura masks.ResultsHere we show that the parasagittal dura volume does not change with age but is significantly correlated with cerebrospinal fluid (p-value = 0.002), extra-axial cerebrospinal fluid volume (p-value = 0.0003) and severity of developmental delay (p-value = 0.024).ConclusionsThese findings suggest that autism spectrum disorder children with severe developmental delay may have a maldeveloped parasagittal dura that potentially perturbs cerebrospinal fluid dynamics.

Early detection of myocardial iron overload in patients with β-thalassemia major using cardiac magnetic resonance T1 mapping

BackgroundThe T2* technique, used for quantifying myocardial iron content (MIC), has limitations in detecting early myocardial iron overload (MIO). The in vivo mapping of the myocardial T1 relaxation time is a promising alternative for the early detection and management of MIO. Methods32 β-thalassemia major (βTM) patients aged 11.5 ± 4 years and 32 healthy controls were recruited and underwent thorough clinical and laboratory assessments. The mid-level septal iron overload was measured through T1 mapping using a modified Look-Locker inversion recovery sequence with a 3 (3 s) 3 (3 s) 5 scheme. Septum was divided at the mentioned level into 3 zones corresponding to segments 8 and 9 in the cardiac segmentation model. Results21.9 % of βTM had clinical cardiac morbidity. The cut-off of T1 mapping of hepatic and myocardium to differentiate between the patients and control groups was ≤466 and ≥ 923 ms respectively. The T1 technique was able to detect 4 patients with high MIC, two of them were not detected by the T2* technique. There was a statistically significant correlation between the average T1 values of the studied zones in patients with βTM and the liver iron content (LIC), the T1 values within segment 8 of the liver, age of patients, the age at first transfusion, age of splenectomy and serum ferritin value. ConclusionThe addition of the T1 mapping sequence to the conventional T2* technique was able to increase the efficacy of the MIC detection protocol by earlier detection of MIO. This would guide chelation therapy to decrease myocardial morbidity.

UTILITY OF CONTRAST-ENHANCED T2-FLAIR FOR IMAGING OF BRAIN METASTASESUSING A HALF-DOSE HIGH-RELAXIVITY CONTRAST AGENT IN COMPARISON WITH ROUTINE DOSE CONTRAST-ENHANCED BRAIN IMAGING

Aim &amp; Objectives: This study aims to assess the efficacy of delayed contrast-enhanced T2 fluid-attenuated inversion recovery (CE-T2 FLAIR) by using half dose high relaxivity contrast agent to assess the degree of enhancement among the lesions and to detect additional metastatic brain lesions usually smaller lesions(&lt;5mm), which are significantly missed on routine-dose CE-T1 weighted imaging (CE-T1WI). Material &amp; Methods:The main source of data for this study was radiologically diagnosed lung cancer patients who were clinically suspected to have brain metastasis referred from various departments of Silchar Medical College and Hospital. The studywas carried out for a period of 1 year from March 1, 2023, to February 29, 2024, A total of 40 patients with brain metastases were scanned using a SIEMENS TIM AVANTO 1.5T scanner, routine MR pulse sequences pre- and post-contrast administration were acquired. Results: Out of 40 patients, males were more affected (57.5 %) than females (42.5 %). The highest number of cases were found between the 61-70 years age group with the lung (31 cases) being the most common primary malignancy causing brain metastases. A total of 90 lesions were detected among 40 patients which were grouped into A (25 lesions), B (36 lesions), and C (29 lesions) groups. A total of 6 lesions were missed on Routine dose contrast-enhanced brain imaging of which 2 lesions belong to group B (Rim enhancing lesions &gt;5mm) and 4 lesions belong to group C (Lesions &lt;5mm), however, these lesions were picked up on delayed half dose contrast-enhanced FLAIR images. The contrast ratio (CR) on 3 consecutive half dose CE-T2 FLAIR ranged between 59.09%-76.80%, suggesting that delay in imaging post-contrast administration resulted in a significant increase in the contrast ratio (CR) among metastatic lesions. Conclusions: CE-T1-weighted sequences and CE-T2 FLAIR sequences complement each other effectively in evaluating brain metastases. Bigger and homogenously enhancing lesions are best seen on CE-T1-weighted sequences. Smaller lesions and lesions showing rim enhancement are best visualized on delayed (5 min) CE-T2 fluid-attenuated inversion recovery (FLAIR) sequences with half the dose ofcontrast agent (gadobenatedimeglumine) compared to routine dose CE-T1-weighted sequences. This approach serves as a cost-saving measure for both patients and the healthcare system.

Fluid-Attenuated Inversion Recovery Sequence in MRI in Distinguishing Fluid Cyst from Tumor in the Brain

Nuclear magnetic resonance (NMR) is a physical phenomenon used to investigate the characteristics of atomic nuclei. It is the absorption and emission of energy by nuclei in a magnetic field, which can offer extensive information on the structure, dynamics, reaction state, and chemical environment of molecules. Magnetic Resonance Imaging (MRI) is the safest imaging method. It gives a visual representation of human tissue without surgical intervention for clinical diagnosis. In this research, Fast Spin Echo (SE), Multi-Slice Spin Echo (MSSE), and Fluid Attenuated Inversion Recovery (FLAIR) sequences were used. The case under study is placed in an i-open permanent MRI system type in order to image a brain lesion. The obtained signals are encoded to fill k-space through the three stages, i.e., slice selection, phase encoding and frequency. The MRI-processed brain image is reconstructed by inverse Fourier transform in order to find the location of the cyst, and T1 weighted, T2 weighted, and FLAIR tests were performed to obtain three types of images. The images were compared with normal images in each type of applied sequence. Subsequently, the fluid signal was specifically attenuated in the targeted location to help distinguish between a tumor and fluid in the transverse relaxation time-weighted image. The signal was attenuated in the designated location, turned black, and appeared the color of free water, like cerebrospinal fluid, indicating that it was a fluid rather than a tumor. Consequently, a cyst fluid lesion is detected. Our study establishes a foundation for utilizing free fluid signal attenuation to differentiate between cyst fluid and tumors when other sequences fail to do the same.

Evaluation of Inflammatory Disease Activity in the Sacroiliac Joints Using Magnetic Resonance Imaging: A Comparative Analysis of Short-Tau Inversion Recovery, Post-Contrast, and Diffusion-Weighted Imaging –Preliminary Study

Introduction: It is essential to detect sacroiliitis earlier to decrease morbidity and unwanted complications such as ankylosing of sacroiliac joints. In recent studies, magnetic resonance imaging (MRI) serves as a key diagnostic tool for identifying sacroiliitis and is now included in the diagnostic criteria. We aim to detect the utility of diffusion-weighted imaging on the MRI in diagnosing sacroiliitis and measure ADC values for the response to treatment in future studies. Materials -methods: There were 39 patients (16 male, 20 female). A 1.5 Tesla MR device with a pelvic coil was used. The sequences were T1 (before and after intravenous contrast administration of gadolinium), T2-weighted fast field echo, short tau inversion recovery (STIR), diffusion-weighted (DW) images, and apparent diffusion coefficient (ADC) mapping. Sacroiliac joints were divided into four quadrants, and two radiologists interpreted all the sequences by giving scores from 0 to 3 depending on bone marrow edema from none to severe. The concordance of scores assigned to STIR, T1-weighted gadolinium-enhanced images, ADC mapping, and diffusion-weighted MR images was evaluated by calculating intraclass correlation coefficients. Results: A statistically significant positive correlation was observed between the activity scores derived from short tau inversion recovery (STIR) and other magnetic resonance (MR) sequences, namely T1-weighted gadolinium-enhanced images, apparent diffusion coefficient (ADC) mapping, and diffusion-weighted MR images. Conclusion: Active bone marrow abnormalities were identified with comparable efficacy using STIR imaging and other MR sequences (T1W-Gad, ADC mapping, DW-MR). In our study, we tried to emphasize the role of the diffusion-weighted images near the other sequences. Diffusion is a fast, easy-applied sequence. After increased experience in the diffusion-weighted images, routine application of this sequence will increase, and even becoming one of the diagnostic criteria will be inevitable. The difference in DWI from the other sequences is that it is measurable. The response to treatment may be followed up by ADC values.

Quantifying the reproducibility and longitudinal repeatability of radiomics features in magnetic resonance Image-Guide accelerator Imaging: A phantom study

ObjectiveThis study aimed to quantitatively evaluate the inter-platform reproducibility and longitudinal acquisition repeatability of MRI radiomics features in Fluid-Attenuated Inversion Recovery (FLAIR), T2-weighted (T2W), and T1-weighted (T1W) sequences on MR-Linac systems using an American College of Radiology (ACR) phantom. Materials and MethodsThis study used two MR-Linac systems (A and B) in different cancer centers. The ACR phantom was scanned on system A daily for 30 consecutive days to evaluate longitudinal repeatability. Additionally, retest data were collected after repositioning the phantom. Inter-platform reproducibility was assessed by conducting scans under identical conditions using system B. Regions of interest were delineated on the T1W sequence from system A and mapped to other sequences via rigid registration. Intra-observer and inter-observer comparisons were conducted. Repeatability and reproducibility were assessed using the intraclass correlation coefficient (ICC) and coefficient of variation (CV). Robust radiomics features were identified based on ICC>0.9 and CV<10 %. ResultsAnalysis showed that a higher proportion of radiomics features derived from longitudinal FLAIR sequence (51.65 %) met robustness criteria compared to T2W (48.35 %) and T1W (43.96 %). Additionally, more inter-platform features from the FLAIR sequence (62.64 %) were robust compared to T2W (42.86 %) and T1W (39.56 %). Test-retest and intra-observer repeatability were excellent across all sequences, with a median ICC of 0.99 and CV<5%. However, inter-observer reproducibility was inferior, especially for the T1W sequence. ConclusionsDifferent sequences show variations in repeatability and reproducibility. The FLAIR sequence demonstrated advantages in both longitudinal repeatability and inter-platform reproducibility. Caution is warranted when interpreting data, particularly in longitudinal or multiplatform radiomics studies.

Utilizing Radiomics of Peri-Lesional Edema in T2-FLAIR Subtraction Digital Images to Distinguish High-Grade Glial Tumors From Brain Metastasis.

Differentiating high-grade glioma (HGG) and isolated brain metastasis (BM) is important for determining appropriate treatment. Radiomics, utilizing quantitative imaging features, offers the potential for improved diagnostic accuracy in this context. To differentiate high-grade (grade 4) glioma and BM using machine learning models from radiomics data obtained from T2-FLAIR digital subtraction images and the peritumoral edema area. Retrospective. The study included 1287 patients. Of these, 602 were male and 685 were female. Of the 788 HGG patients included in the study, 702 had solitary masses. Of the 499 BM patients included in the study, 112 had solitary masses. Initially, the model was developed and tested on solitary masses. Subsequently, the model was developed and tested separately for all patients (solitary and multiple masses). Axial T2-weighted fast spin-echo sequence (T2WI) and T2-weighted fluid-attenuated inversion recovery sequence (T2-FLAIR), using 1.5-T and 3.0-T scanners. Radiomic features were extracted from digitally subtracted T2-FLAIR images in the area of peritumoral edema. The maximum relevance-minimum redundancy (mRMR) method was then used for dimensionality reduction. The naive Bayes algorithm was used in model development. The interpretability of the model was explored using SHapley Additive exPlanations (SHAP). Chi-square test, one-way analysis of variance, and Kruskal-Wallis test were performed. The P values <0.05 were considered statistically significant. The performance metrics include area under curve (AUC), sensitivity (SENS), and specificity (SPEC). The mean age of HGG patients was 61.4 ± 13.2 years and 61.7 ± 12.2 years for BM patients. In the external validation cohort, the model achieved AUC: 0.991, SENS: 0.983, and SPEC: 0.922. The external cohort results for patients with solitary lesions were AUC: 0.987, SENS: 0.950, and SPEC: 0.922. The artificial intelligence model, developed with radiomics data from the peritumoral edema area in T2-FLAIR digital subtraction images, might be able to differentiate isolated BM from HGG. 3 TECHNICAL EFFICACY: Stage 2.

Watershed regions are more susceptible to tissue microstructural injury in multiple sclerosis.

Histopathologic studies report higher concentrations of multiple sclerosis white matter lesions in watershed areas of the brain, suggesting that areas with relatively lower oxygen levels may be more vulnerable to disease. However, it is unknown at what point in the disease course lesion predilection for watershed territories begins. Accordingly, we studied a cohort of people with newly diagnosed disease and asked whether (1) white matter lesions disproportionally localize to watershed-regions and (2) the degree of microstructural injury in watershed-lesions is more severe. Fifty-four participants, i.e. 38 newly diagnosed people with multiple sclerosis, clinically isolated syndrome or radiologically isolated syndrome, and 16 age- and sex-matched healthy controls underwent brain magnetic resonance imaging. T1-weighted and T2-weighted fluid-attenuated inversion recovery sequences, selective inversion recovery quantitative magnetisation transfer images, and the multi-compartment diffusion imaging with the spherical mean technique were acquired. We computed the macromolecular-to-free pool size ratio, and the apparent axonal volume fraction maps to indirectly estimate myelin and axonal integrity, respectively. We produced a flow territory atlas in each subject's native T2-weighted fluid-attenuated inversion recovery images using a T1-weighted magnetic resonance imaging template in the Montreal Neurological Institute 152 space. Lesion location relative to the watershed, non-watershed and mixed brain vascular territories was annotated. The same process was performed on the T2-weighted fluid-attenuated inversion recovery images of the healthy controls using 294 regions of interest. Generalized linear mixed models for continuous outcomes were used to assess differences in size, pool size ratio and axonal volume fraction between lesions/regions of interests (in healthy controls) situated in different vascular territories. In patients, we assessed 758 T2-lesions and 356 chronic black holes (cBHs). The watershed-territories had higher relative and absolute concentrations of T2-lesions (P≤0.041) and cBHs (P≤0.036) compared to either non-watershed- or mixed-zones. T2-lesions in watershed-areas also had lower pool size ratio relative to T2-lesions in either non-watershed- or mixed-zones (P = 0.039). These results retained significance in the sub-cohort of people without vascular comorbidities and when accounting for periventricular lesions. In healthy controls, axonal volume fraction was higher only in mixed-areas regions of interest compared to non-watershed-ones (P = 0.008). No differences in pool size ratio were seen. We provide in vivo evidence that there is an association between arterial vascularisation of the brain and multiple sclerosis-induced tissue injury as early as the time of disease diagnosis. Our findings underline the importance of oxygen delivery and healthy arterial vascularisation to prevent lesion formation and foster a better outcome in multiple sclerosis.

Predicting white-matter hyperintensity progression and cognitive decline in patients with cerebral small-vessel disease: a magnetic resonance-based habitat analysis.

White-matter hyperintensity (WMH) is the key magnetic resonance imaging (MRI) marker of cerebral small-vessel disease (CSVD). This study aimed to investigate whether habitat analysis based on physiologic MRI parameters can predict the progression of WMH and cognitive decline in CSVD. Diffusion- and perfusion-weighted imaging data were obtained from 69 patients with CSVD at baseline and at 1-year of follow-up. The white-matter region was classified into constant WMH, growing WMH, shrinking WMH, and normal-appearing white matter (NAWM) according to the T2-fluid-attenuated inversion recovery (FLAIR) sequences images at the baseline and follow-up. We employed k-means clustering on a voxel-wise basis to delineate WMH habitats, integrating multiple diffusion metrics and cerebral blood flow (CBF) values derived from perfusion data. The WMH at the baseline and the predicted WMH from the habitat analysis were used as regions of avoidance (ROAs). The decreased rate of global efficiency for the whole brain structural connectivity was calculated after removal of the ROA. The association between the decreased rate of global efficiency and Montreal Cognitive Assessment (MoCA) and mini-mental state examination (MMSE) scores was evaluated using Pearson correlation coefficients. We found that the physiologic MRI habitats with lower fractional anisotropy and CBF values and higher mean diffusivity, axial diffusivity, and radial diffusivity values overlapped considerably with the new WMH (growing WMH of baseline) after a 1-year follow-up; the accuracy of distinguishing growing WMH from NAWM was 88.9%±12.7% at baseline. Similar results were also found for the prediction of shrinking WMH. Moreover, after the removal of the predicted WMH, a decreased rate of global efficiency had a significantly negative correlation with the MoCA and MMSE scores at follow-up. This study revealed that a habitat analysis combining perfusion with diffusion parameters could predict the progression of WMH and related cognitive decline in patients with CSVD.

Differentiation between multifocal CNS lymphoma and glioblastoma based on MRI criteria

PurposeDifferentiating between glioblastoma (GB) with multiple foci (mGB) and multifocal central nervous system lymphoma (mCNSL) can be challenging because these cancers share several features at first appearance on magnetic resonance imaging (MRI). The aim of this study was to explore morphological differences in MRI findings for mGB versus mCNSL and to develop an interpretation algorithm with high diagnostic accuracy.MethodsIn this retrospective study, MRI characteristics were compared between 50 patients with mGB and 50 patients with mCNSL treated between 2015 and 2020. The following parameters were evaluated: size, morphology, lesion location and distribution, connections between the lesions on the fluid-attenuated inversion recovery sequence, patterns of contrast enhancement, and apparent diffusion coefficient (ADC) values within the tumor and the surrounding edema, as well as MR perfusion and susceptibility weighted imaging (SWI) whenever available.ResultsA total of 187 mCNSL lesions and 181 mGB lesions were analyzed. The mCNSL lesions demonstrated frequently a solid morphology compared to mGB lesions, which showed more often a cystic, mixed cystic/solid morphology and a cortical infiltration. The mean measured diameter was significantly smaller for mCNSL than mGB lesions (p < 0.001). Tumor ADC ratios were significantly smaller in mCNSL than in mGB (0.89 ± 0.36 vs. 1.05 ± 0.35, p < 0.001). The ADC ratio of perilesional edema was significantly higher (p < 0.001) in mCNSL than in mGB. In SWI / T2*-weighted imaging, tumor-associated susceptibility artifacts were more often found in mCNSL than in mGB (p < 0.001).ConclusionThe lesion size, ADC ratios of the lesions and the adjacent tissue as well as the vascularization of the lesions in the MR-perfusion were found to be significant distinctive patterns of mCNSL and mGB allowing a radiological differentiation of these two entities on initial MRI. A diagnostic algorithm based on these parameters merits a prospective validation.