Evaluation of 3D T1-weighted spoiled gradient echo MR image quality using artificial intelligence image reconstruction techniques in the pediatric brain.

PURPOSE: To assess image quality and diagnostic confidence of 3D T1-weighted spoiled gradient echo (SPGR) MRI using artificial intelligence (AI) reconstruction. MATERIALS AND METHODS: This prospective, IRB-approved study enrolled 50 pediatric patients (mean age = 11.8 ± 3.1 years) undergoing clinical brain MRI. In addition to standard of care (SOC) compressed SENSE (CS = 2.5), 3D T1-weighted SPGR images were obtained with higher CS acceleration factors (5 and 8) to evaluate the ability of AI reconstruction to improve image quality and reduce scan time. Images were reviewed independently on dedicated research PACS workstations by two neuroradiologists. Quantitative analysis of signal intensities to calculate apparent grey and white matter signal to noise (aSNR) and grey-white matter apparent contrast to noise ratios (aCNR) was performed. RESULTS: AI improved overall image quality compared to standard CS reconstruction in 35% (35/100) of evaluations in CS = 2.5 (average scan time = 221 ± 6.9 s), 100% (46/46) of CS = 5 (average scan time = 113.3 ± 4.6 s) and 94% (47/50) of CS = 8 (average scan time = 74.1 ± 0.01 s). Quantitative analysis revealed significantly higher grey matter aSNR, white matter aSNR and grey-white matter aCNR with AI reconstruction compared to standard reconstruction for CS 5 and 8 (all p-values < 0.001), however not for CS 2.5. CONCLUSIONS: AI reconstruction improved overall image quality and gray-white matter qualitative and quantitative aSNR and aCNR in highly accelerated (CS = 5 and 8) 3D T1W SPGR images in the majority of pediatric patients.

Evaluation of T2W FLAIR MR image quality using artificial intelligence image reconstruction techniques in the pediatric brain.

BACKGROUND: Artificial intelligence (AI) reconstruction techniques have the potential to improve image quality and decrease imaging time. However, these techniques must be assessed for safe and effective use in clinical practice. OBJECTIVE: To assess image quality and diagnostic confidence of AI reconstruction in the pediatric brain on fluid-attenuated inversion recovery (FLAIR) imaging. MATERIALS AND METHODS: This prospective, institutional review board (IRB)-approved study enrolled 50 pediatric patients (median age=12 years, Q1=10 years, Q3=14 years) undergoing clinical brain MRI. T2-weighted (T2W) FLAIR images were reconstructed by both standard clinical and AI reconstruction algorithms (strong denoising). Images were independently rated by two neuroradiologists on a dedicated research picture archiving and communication system (PACS) to indicate whether AI increased, decreased, or had no effect on image quality compared to standard reconstruction. Quantitative analysis of signal intensities was also performed to calculate apparent signal to noise (aSNR) and apparent contrast to noise (aCNR) ratios. RESULTS: AI reconstruction was better than standard in 99% (reader 1, 49/50; reader 2, 50/50) for overall image quality, 99% (reader 1, 49/50; reader 2, 50/50) for subjective SNR, and 98% (reader 1, 49/50; reader 2, 49/50) for diagnostic preference. Quantitative analysis revealed significantly higher gray matter aSNR (30.6±6.5), white matter aSNR (21.4±5.6), and gray-white matter aCNR (7.1±1.6) in AI-reconstructed images compared to standard reconstruction (18±2.7, 14.2±2.8, 4.4±0.8, p<0.001) respectively. CONCLUSION: We conclude that AI reconstruction improved T2W FLAIR image quality in most patients when compared with standard reconstruction in pediatric patients.

Magnetic resonance imaging T1 mapping of the liver, pancreas and spleen in children.

PURPOSE: To characterize T1 relaxation times of the pancreas, liver, and spleen in children with and without abdominal pathology. METHODS: This retrospective study included pediatric patients (< 18-years-old). T1 mapping was performed with a Modified Look-Locker Inversion Recovery sequence. Patients were grouped based on review of imaging reports and electronic medical records. The Kruskal-Wallis test with Dunn's multiple comparison was used to compare groups. RESULTS: 220 participants were included (mean age: 11.4 ± 4.2 years (1.5 T); 10.9 ± 4.5 years (3 T)). Pancreas T1 (msec) was significantly different between subgroups at 1.5 T (p < 0.0001). Significant pairwise differences included: normal (median: 583; IQR: 561-654) vs. acute pancreatitis (731; 632-945; p = 0.0024), normal vs. chronic pancreatitis (700; 643-863; p = 0.0013), and normal vs. acute + chronic pancreatitis (1020; 897-1099; p < 0.0001). Pancreas T1 was also significantly different between subgroups at 3 T (p < 0.0001). Significant pairwise differences included: normal (779; 753-851) vs. acute pancreatitis (1087; 910-1259; p = 0.0012), and normal vs. acute + chronic pancreatitis (1226; 1025-1367; p < 0.0001). Liver T1 was significantly different between subgroups only at 3 T (p = 0.0011) with pairwise differences between normal (818, 788-819) vs. steatotic (959; 848-997; p = 0.0017) and normal vs. other liver disease (882; 831-904; p = 0.0455). Liver T1 was weakly correlated with liver fat fraction at 1.5 T (r = 0.39; 0.24-0.52; p < 0.0001) and moderately correlated at 3 T (r = 0.64; 0.49-0.76; p < 0.0001). There were no significant differences in splenic T1 relaxation times between subgroups. CONCLUSION: Pancreas T1 relaxation times are higher at 1.5 T and 3 T in children with pancreatitis and liver T1 relaxation times are higher in children with steatotic and non-steatotic chronic liver disease at 3 T.

Prospective characterization of intestinal MRI intravoxel incoherent motion in pediatric and young adult patients with newly diagnosed small bowel Crohn's disease.

BACKGROUND: MRI diffusion-weighted imaging (DWI) is commonly used in MR enterography protocols for assessment of intestinal inflammation in patients with Crohn's disease. The intravoxel incoherent motion (IVIM) approach to DWI has been proposed as a more objective approach, providing quantitative parameters that reflect water diffusivity (D), blood flow (D*), and perfusion fraction (f). PURPOSE: We aimed to determine if DWI-IVIM metrics from the terminal ileum in patients with newly diagnosed Crohn's disease differ from healthy participants and change in response to biologic medical therapy. METHODS: In this prospective case-control study, 20 consecutive pediatric patients (mean age = 14 years ± 2 [SD]; eight females) with newly diagnosed ileal Crohn's disease and 15 pediatric healthy participants (mean age = 18 years ± 4 [SD]; eight females) underwent research MRI examinations of the small bowel between 12/2018 and 10/2021. Participants with Crohn's disease underwent MR studies at baseline, 6 weeks, and 6 months following initiation of anti-TNF-alpha therapy, whereas control participants underwent one research MRI examination. The MRI protocol included a DWI-IVIM sequence with nine b-values and the IVIM parameters (D, D*, and f) were extracted. Unpaired t-tests and mixed-effects models were used for analyses. RESULTS: Mean IVIM D (P < 0.001), D* (P = 0.004), and f (P = 0.001) metrics were lower for Crohn's patients at the time of diagnosis compared to healthy participants. Mean IVIM f value increased over time in response to medical therapy (mean f at baseline, 22% ± 6%; 6 weeks, 25% ± 7%; 6 months, 29% ± 10%; P = 0.016). Mean IVIM D* value increased over time in response to treatment (mean D* at baseline, 10.9 ± 3.0 × 10-3 mm2/s; 6 weeks, 11.8 ± 2.8 × 10-3 mm2/s; 6 months, 13.3 ± 3.3 × 10-3 mm2/s; P = 0.047), while there was no significant change in mean IVIM D value (P = 0.10). CONCLUSION: MRI DWI-IVIM metrics in patients with ileal Crohn's disease change over time in response to biological therapy and help discriminate these patients from healthy participants.

MRI and Blood-based Biomarkers Are Associated With Surgery in Children and Adults With Ileal Crohn's Disease.

BACKGROUND: Despite advances in medical therapy, many children and adults with ileal Crohn's disease (CD) progress to fibrostenosis requiring surgery. We aimed to identify MRI and circulating biomarkers associated with the need for surgical management. METHODS: This prospective, multicenter study included pediatric and adult CD cases undergoing ileal resection and CD controls receiving medical therapy. Noncontrast research MRI examinations measured bowel wall 3-dimensional magnetization transfer ratio normalized to skeletal muscle (normalized 3D MTR), modified Look-Locker inversion recovery (MOLLI) T1 relaxation, intravoxel incoherent motion (IVIM) diffusion-weighted imaging metrics, and the simplified magnetic resonance index of activity (sMaRIA). Circulating biomarkers were measured on the same day as the research MRI and included CD64, extracellular matrix protein 1 (ECM1), and granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies (Ab). Associations between MRI and circulating biomarkers and need for ileal resection were tested using univariate and multivariable LASSO regression. RESULTS: Our study sample included 50 patients with CD undergoing ileal resection and 83 patients with CD receiving medical therapy; mean participant age was 23.9 ±â€…13.1 years. Disease duration and treatment exposures did not vary between the groups. Univariate biomarker associations with ileal resection included log GM-CSF Ab (odds ratio [OR], 2.87; P = .0009), normalized 3D MTR (OR, 1.05; P = .002), log MOLLI T1 (OR, 0.01; P = .02), log IVIM perfusion fraction (f; OR, 0.38; P = .04), and IVIM apparent diffusion coefficient (ADC; OR, 0.3; P = .001). The multivariable model for surgery based upon corrected Akaike information criterion included age (OR, 1.03; P = .29), BMI (OR, 0.91; P = .09), log GM-CSF Ab (OR, 3.37; P = .01), normalized 3D MTR (OR, 1.07; P = .007), sMaRIA (OR, 1.14; P = .61), luminal narrowing (OR, 10.19; P = .003), log C-reactive protein (normalized; OR, 2.75; P = .10), and hematocrit (OR, 0.90; P = .13). CONCLUSION: After accounting for clinical and MRI measures of severity, normalized 3D MTR and GM-CSF Ab are associated with the need for surgery in ileal CD.

Despite advances in medical therapy, many patients with ileal Crohn's disease progress to fibrostenosis requiring surgery. Our study has shown that GM-CSF autoantibodies and MRI biomarker sequences are associated with the need for ileal resection and may help guide management decisions.

Precision and Test-Retest Repeatability of Stiffness Measurement with MR Elastography: A Multicenter Phantom Study.

Background MR elastography (MRE) has been shown to have excellent performance for noninvasive liver fibrosis staging. However, there is limited knowledge regarding the precision and test-retest repeatability of stiffness measurement with MRE in the multicenter setting. Purpose To determine the precision and test-retest repeatability of stiffness measurement with MRE across multiple centers using the same phantoms. Materials and Methods In this study, three cylindrical phantoms made of polyvinyl chloride gel mimicking different degrees of liver stiffness in humans (phantoms 1-3: soft, medium, and hard stiffness, respectively) were evaluated. Between January 2021 and January 2022, phantoms were circulated between five different centers and scanned with 10 MRE-equipped clinical 1.5-T and 3-T systems from three major vendors, using two-dimensional (2D) gradient-recalled echo (GRE) imaging and/or 2D spin-echo (SE) echo-planar imaging (EPI). Similar MRE acquisition parameters, hardware, and reconstruction algorithms were used at each center. Mean stiffness was measured by a single observer for each phantom and acquisition on a single section. Stiffness measurement precision and same-session test-retest repeatability were assessed using the coefficient of variation (CV) and the repeatability coefficient (RC), respectively. Results The mean precision represented by the CV was 5.8% (95% CI: 3.8, 7.7) for all phantoms and both sequences combined. For all phantoms, 2D GRE achieved a CV of 4.5% (95% CI: 3.3, 5.7) whereas 2D SE EPI achieved a CV of 7.8% (95% CI: 3.1, 12.6). The mean RC of stiffness measurement was 5.8% (95% CI: 3.7, 7.8) for all phantoms and both sequences combined, 4.9% (95% CI: 2.7, 7.0) for 2D GRE, and 7.0% (95% CI: 2.9, 11.2) for 2D SE EPI (all phantoms). Conclusion MRE had excellent in vitro precision and same-session test-retest repeatability in the multicenter setting when similar imaging protocols, hardware, and reconstruction algorithms were used. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Tang in this issue.

Implementation of a Program for Appendicitis MRI in a Pediatric Hospital.

MRI is increasingly used as an alternate to CT for the evaluation of suspected appendicitis in pediatric patients presenting to the emergency department (ED) with abdominal pain, when further imaging is needed after an initial ultrasound examination. The available literature shows a similar diagnostic performance of MRI and CT in this setting. At the authors' institution, to evaluate for appendicitis in children in the ED, MRI is performed using a rapid three-sequence free-breathing protocol without IV contrast media. Implementation of an MRI program for appendicitis in children involves multiple steps, including determination of imaging resource availability, collaboration with other services to develop imaging pathways, widespread educational efforts, and regular quality review. Such programs can face numerous practice-specific challenges, such as those involving scanner capacity, costs, and buy-in of impacted groups. Nonetheless, through careful consideration of these factors, MRI can be used to positively impact the care of children presenting to the ED with suspected appendicitis. This Clinical Perspective aims to provide guidance on the development of a program for appendicitis MRI in children, drawing on one institution's experience while highlighting the advantages of MRI and practical strategies for overcoming potential barriers.

MR and Ultrasound Elastography for Fibrosis Assessment in Children: Practical Implementation and Supporting Evidence-AJR Expert Panel Narrative Review.

Quantitative MRI and ultrasound biomarkers of liver fibrosis have become important tools in the diagnosis and clinical management of children with chronic liver disease (CLD). In particular, MR elastography (MRE) is now routinely performed in clinical practice to evaluate the liver for fibrosis. Ultrasound shear-wave elastography has also become widely performed for this purpose, especially in young children. These noninvasive methods are increasingly used to replace liver biopsy for the diagnosis, quantitative staging, and treatment monitoring of patients with CLD. Although ultrasound has advantages of portability and lower equipment cost, available evidence indicates that MRI may have greater reliability and accuracy in liver fibrosis evaluation. In this AJR Expert Panel Narrative Review, we describe how, why, and when to use MRI- and ultrasound-based elastography methods for liver fibrosis assessment in children. Practical approaches are discussed for adapting and optimizing these methods in children, with consideration of clinical indications, patient preparation, equipment requirements, acquisition technique, as well as pitfalls and confounding factors. Guidance is provided for interpretation and reporting, and representative case examples are presented.

Machine Learning Diagnosis of Small-Bowel Crohn Disease Using T2-Weighted MRI Radiomic and Clinical Data.

BACKGROUND. Radiologists have variable diagnostic performance and considerable interreader variability when interpreting MR enterography (MRE) examinations for suspected Crohn disease (CD). OBJECTIVE. The purposes of this study were to develop a machine learning method for predicting ileal CD by use of radiomic features of ileal wall and mesenteric fat from noncontrast T2-weighted MRI and to compare the performance of the method with that of expert radiologists. METHODS. This single-institution study included retrospectively identified patients who underwent MRE for suspected ileal CD from January 1, 2020, to January 31, 2021, and prospectively enrolled participants (patients with newly diagnosed ileal CD or healthy control participants) from December 2018 to October 2021. Using axial T2-weighted SSFSE images, a radiologist selected two slices showing greatest terminal ileal wall thickening. Four ROIs were segmented, and radiomic features were extracted from each ROI. After feature selection, support-vector machine models were trained to classify the presence of ileal CD. Three fellowship-trained pediatric abdominal radiologists independently classified the presence of ileal CD on SSFSE images. The reference standard was clinical diagnosis of ileal CD based on endoscopy and biopsy results. Radiomic-only, clinical-only, and radiomic-clinical ensemble models were trained and evaluated by nested cross-validation. RESULTS. The study included 135 participants (67 female, 68 male; mean age, 15.2 ± 3.2 years); 70 were diagnosed with ileal CD. The three radiologists had accuracies of 83.7% (113/135), 88.1% (119/135), and 86.7% (117/135) for diagnosing CD; consensus accuracy was 88.1%. Interradiologist agreement was substantial (κ = 0.78). The best-performing ROI was bowel core (AUC, 0.95; accuracy, 89.6%); other ROIs had worse performance (whole-bowel AUC, 0.86; fat-core AUC, 0.70; whole-fat AUC, 0.73). For the clinical-only model, AUC was 0.85 and accuracy was 80.0%. The ensemble model combining bowel-core radiomic and clinical models had AUC of 0.98 and accuracy of 93.5%. The bowel-core radiomic-only model had significantly greater accuracy than radiologist 1 (p = .009) and radiologist 2 (p = .02) but not radiologist 3 (p > .99) or the radiologists in consensus (p = .05). The ensemble model had greater accuracy than the radiologists in consensus (p = .02). CONCLUSION. A radiomic machine learning model predicted CD diagnosis with better performance than two of three expert radiologists. Model performance improved when radiomic data were ensembled with clinical data. CLINICAL IMPACT. Deployment of a radiomic-based model including T2-weighted MRI data could decrease interradiologist variability and increase diagnostic accuracy for pediatric CD.

Technical and Diagnostic Performance of Rapid MRI for Evaluation of Appendicitis in a Pediatric Emergency Department.

RATIONALE AND OBJECTIVES: Rationale MRI is increasingly used for diagnosis of pediatric appendicitis in the emergency care setting. Scan and room time are important to optimize workflow, especially in situations with limited MRI availability and accessibility. To describe our process to optimize and implement a rapid, non-contrast, free-breathing MRI protocol for appendicitis and to characterize the accuracy for diagnosis. MATERIALS AND METHODS: Initial MRI protocol implemented for suspected appendicitis included five respiratory-triggered axial and coronal single shot fast spin echo (SSFSE) and radial T2W sequences with and without fat suppression (FS). This protocol was reassessed based on image quality. Subsequently, the coronal and axial T2W SSFSE FS sequence were removed. A three-sequence exam comprised the rapid MRI appendicitis protocol used for the remainder of the study. All examinations were performed on a 1.5 T scanner. For all examinations, the following information was obtained: scan time, diagnosis of appendicitis (by radiology report), surgery and pathology reports, and alternative diagnoses documented in radiology reports. MRI examination scan durations were compared between the five-sequence and three-sequence protocols, with Mann-Whitney U test, and proportions of false diagnoses were compared to Fisher's exact test. RESULTS: 216 examinations were performed; 21 and 195 performed with five- and three-sequence protocol, respectively. The median duration of the five-sequence protocol was 20 (16.9-23.5) minutes vs.11 (9.5-13) minutes for the three sequence protocol (p < 0.0001). The majority (n = 157, 80.5% of 195) of examinations were performed in a goal time of< 15 min. 23 examinations took longer than 20 min (n = 12, n = 11 for the three- and five-sequence protocols, respectively) were due to repeat sequences or addition of non-standard sequences (requested by interpreting radiologist). 27 (90%) of the 30 reported positive cases were confirmed by pathology. There were three false-positive diagnoses (all three-sequence protocol exams) and one false-negative diagnosis (five-sequence protocol exam). Alternative diagnoses, including pancreatitis, omental infarct, masses, and ovarian pathology, were made in 42 (19%) cases. CONCLUSION: A three-sequence, non-contrast, free- breathing MRI examination can be performed in less than 15 min in the emergency department and has high diagnostic accuracy for acute appendicitis in children and young adults.

Accelerated Cine Cardiac MRI Using Deep Learning-Based Reconstruction: A Systematic Evaluation.

BACKGROUND: Breath-holding (BH) for cine balanced steady state free precession (bSSFP) imaging is challenging for patients with impaired BH capacity. Deep learning-based reconstruction (DLR) of undersampled k-space promises to shorten BHs while preserving image quality and accuracy of ventricular assessment. PURPOSE: To perform a systematic evaluation of DLR of cine bSSFP images from undersampled k-space over a range of acceleration factors. STUDY TYPE: Retrospective. SUBJECTS: Fifteen pectus excavatum patients (mean age 16.8 ± 5.4 years, 20% female) with normal cardiac anatomy and function and 12-second BH capability. FIELD STRENGTH/SEQUENCE: 1.5-T, cine bSSFP. ASSESSMENT: Retrospective DLR was conducted by applying compressed sensitivity encoding (C-SENSE) acceleration to systematically undersample fully sampled k-space cine bSSFP acquisition data over an acceleration/undersampling factor (R) considering a range of 2 to 8. Quality imperceptibility (QI) measures, including structural similarity index measure, were calculated using images reconstructed from fully sampled k-space as a reference. Image quality, including contrast and edge definition, was evaluated for diagnostic adequacy by three readers with varying levels of experience in cardiac MRI (>4 years, >18 years, and 1 year). Automated DL-based biventricular segmentation was performed commercially available software by cardiac radiologists with more than 4 years of experience. STATISTICAL TESTS: Tukey box plots, linear mixed effects model, analysis of variance (ANOVA), weighted kappa, Kruskal-Wallis test, and Wilcoxon signed-rank test were employed as appropriate. A P-value <0.05 was considered statistically significant. RESULTS: There was a significant decrease in the QI values and edge definition scores as R increased. Diagnostically adequate image quality was observed up to R = 5. The effect of R on all biventricular volumetric indices was non-significant (P = 0.447). DATA CONCLUSION: The biventricular volumetric indices obtained from the reconstruction of fully sampled cine bSSFP acquisitions and DLR of the same k-space data undersampled by C-SENSE up to R = 5 may be comparable. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 1.

Liver T1 Relaxation Quantification Using a 3-Dimensional Interleaved Look-Locker Acquisition With T2 Preparation Pulse Sequence (3D-QALAS): Comparison With Conventional 2-Dimensional MOLLI.

BACKGROUND: Changes in liver magnetic resonance imaging T1 relaxation times are associated with histologic inflammation and fibrosis. OBJECTIVE: To compare liver T1 measurements obtained using a novel single-breath-hold 3-dimensional (3D) whole-liver T1 estimation method (3D-QALAS) to standard-of-care 2-dimensional (2D) modified Look-Locker (2D-MOLLI) measurements. METHODS: With institutional review board approval, research magnetic resonance imaging examinations were performed in 19 participants at 1.5 T. T1 relaxometry of the liver was performed using a novel 3D whole-liver T1 estimation method (3D-QALAS) as well as a 2D modified Look-Locker (2D-MOLLI) method. The 3D method covered the entire liver in a single breath hold, whereas 2D imaging was performed at 4 anatomic levels in 4 consecutive breath holds. T1 measurements from parametric maps were obtained by a single operator, and region-of-interest area-weighted mean T1 values were calculated. Pearson correlation ( r ) was used to assess correlation between T1 estimation methods, and the paired t test and Bland-Altman analysis were used to compare agreement in T1 measurements. RESULTS: In 18 participants (1 participant was excluded from analysis because of respiratory motion artifacts on 3D-QALAS images), 2D-MOLLI and 3D-QALAS mean T1 measurements were strongly correlated ( r = 0.95, [95% CI: 0.87-0.98]; P < 0.0001). 2D-MOLLI T1 values were significantly longer than 3D-QALAS values (647.2 ± 87.3 milliseconds vs. 554.7 ± 75.8 milliseconds; P < 0.0001) with mean bias = 92.5 milliseconds (95% limits of agreement, 36.8, 148.2 milliseconds). CONCLUSION: Whole-liver T1 measurements obtained using a novel single-breath-hold 3D T1 estimation method correlate with a standard-of-care multiple consecutive-breath-hold 2D single-slice method but demonstrate systematic bias that should be considered or corrected when used in a clinical or research setting.

MRI safety screening of children with implants: updates and challenges.

MRI is the imaging modality of choice for assessing many pediatric medical conditions. Although there are several inherent potential safety risks associated with the electromagnetic fields exploited for MRI, they are effectively mitigated through strict adherence to established MRI safety practices, enabling the safe and effective use of MRI in clinical practice. The potential hazards of the MRI environment may be exacerbated by/in the presence of implanted medical devices. Awareness of the unique MRI safety and screening challenges associated with these implanted devices is critical to ensuring MRI safety for the affected patients. In this review article, we will discuss the basics of MRI physics as they relate to MRI safety in the presence of implanted medical devices, strategies for assessing children with known or suspected implanted medical devices, and the particular management of several well-established common, as well as recently developed, implanted devices encountered at our institution.

Respiratory-Triggered Flow-Independent Noncontrast Non-ECG-Gated MRV (REACT) Versus CE-MRV for Central Venous Evaluation in Children and Young Adults: A Six-Reader Study.

BACKGROUND. Contrast-enhanced MRI is commonly used to evaluate thoracic central venous patency in children and young adults. A flow-independent noncontrast non-ECG-gated 3D MRA-MR venography (MRV) technique described in 2019 as "relaxation-enhanced angiography without contrast and triggering (REACT)" may facilitate such evaluation. OBJECTIVE. The purpose of our study was to compare image quality, diagnostic confidence, and interreader agreement between respiratory-triggered REACT and 3D Dixon-based contrast-enhanced MRV (CE-MRV) for evaluating thoracic central venous patency in children and young adults. METHODS. This retrospective study included 42 consecutive children and young adults who underwent MRI of the neck and chest to evaluate central venous patency between August 2019 and January 2021 (median age, 5.2 years; IQR, 1.4-15.1 years; 22 female patients and 20 male patients). Examinations included respiratory-triggered REACT and navigator-gated CE-MRV sequences based on the institution's standard-of-care protocol. Six pediatric radiologists from four different institutions independently reviewed REACT and CE-MRV sequences; they assessed overall image quality (scale, 1-5; 5 = excellent), diagnostic confidence (scale, 1-5; 5 = extremely confident), and presence of clinically relevant artifact(s). Readers classified seven major central vessels as normal or abnormal (e.g., narrowing, thrombosis, or occlusion). Analysis used Wilcoxon signed rank and McNemar tests and Fleiss kappa coefficients. RESULTS. The distribution of overall image quality scores was higher (p = .02) for REACT than for CE-MRV for one reader (both sequences: median score, 5). Image quality scores were not significantly different between the sequences for the remaining five readers (all p > .05). Diagnostic confidence scores and frequency of clinically relevant artifact(s) were not significantly different between sequences for any reader (all p > .05). Interreader agreement for vessel classification as normal or abnormal was similar between sequences for all seven vessels (REACT: κ = 0.37-0.81; CE-MRV: κ = 0.34-0.81). Pooling readers and vessels, 65.4% of vessels were normal by both sequences; 18.7%, abnormal by both sequences; 9.8%, abnormal by REACT only; and 6.1%, abnormal by CE-MRV only. CONCLUSION. Respiratory-triggered REACT, in comparison with CE-MRV, showed no significant difference in image quality (aside from for one of six readers), diagnostic confidence, or frequency of artifact(s), with similar interreader agreement for vessel classification as normal or abnormal. CLINICAL IMPACT. High-resolution 3D MRV performed without IV contrast material can be used to assess central venous patency in children and young adults.

The Simplified MR Index of Activity Score in Pediatric Small-Bowel Crohn Disease: An Interreader Agreement and Responsiveness Study.

BACKGROUND. The simplified MR index of activity (MaRIA) score is used to assess the severity of small-bowel inflammation without use of IV contrast material. OBJECTIVE. The purposes of this study were to assess interreader agreement on the use of simplified MaRIA scores for evaluation of the inflammatory activity of terminal ileal Crohn disease in children and young adults and to assess whether simplified MaRIA scores change after biologic medical therapy. METHODS. This analysis was ancillary to a previously reported primary prospective research investigation. The study included 20 children and young adults with newly diagnosed ileal Crohn disease and 15 healthy control participants who underwent research small-bowel MRI examinations between December 2018 and October 2021. The participants with Crohn disease underwent baseline MRI and MRI 6 weeks and 6 months after beginning anti-tumor necrosis factor α-treatment as well as weighted pediatric Crohn disease activity index (wPCDAI) and C-reactive protein (CRP) assessment on the day of each examination. Control participants underwent one MRI examination. Four pediatric radiologists independently assigned simplified MaRIA scores using axial and coronal T2-weighted SSFSE images. Median simplified MaRIA score among readers was computed. Interreader agreement was assessed with Fleiss kappa coefficients and intra-class correlation coefficient (ICC). Analysis included the Mann-Whitney U test, Friedman test, and Spearman rank correlation. RESULTS. Simplified MaRIA scores (across time points and study groups) had substantial interreader agreement (κ = 0.65 [95% CI, 0.56-0.74]; ICC, 0.71 [95% CI, 0.63-0.78]). Median scores were higher in participants with Crohn disease at baseline than in healthy control participants (3.5 [IQR, 2.5-4.9] vs 0.5 [IQR, 0-2.0]; p < .001). Scores decreased after medical treatment in participants with Crohn disease (p = .005). The median score was 3.5 (IQR, 2.5-4.9) at baseline, 2.3 (IQR, 1.6-3.9) at 6 weeks, and 2.0 (IQR, 0.5-2.5) at 6 months. In participants with Crohn disease, median scores had significant correlations with wPCDAI (ρ = 0.46 [95% CI, 0.18-0.64]; p < .001) and CRP level (ρ = 0.48 [95% CI, 0.27-0.65]; p < .001). CONCLUSION. Radiologists had substantial agreement in use of simplified MaRIA scores to assess intestinal inflammation in ileal Crohn disease. Scores changed over time after medical therapy. CLINICAL IMPACT. The results support the simplified MaRIA score as an objective MRI-based clinical measure of intestinal inflammation in children and young adults with Crohn disease.

Prospective characterization of incident hepatic steatosis in pediatric and adolescent patients after total pancreatectomy with islet autotransplantation.

BACKGROUND: Hepatic steatosis has been described as a common finding in adults following total pancreatectomy with islet autotransplantation (TPIAT) but it is unknown if this occurs in children and adolescents. OBJECTIVES: To define the frequency of post-TPIAT hepatic steatosis in a sample of children and adolescents and to identify clinical predictors of incident steatosis post-TPIAT. METHODS: In this prospective study, consecutive participants at least 1-month post-TPIAT underwent a liver MRI with proton density fat fraction (PDFF) and blood draw at our pediatric academic medical center between April 2021 and January 2022. Comparison clinical pre-TPIAT liver MRI or ultrasound and insulin use and graft function data were extracted from the medical record. T-tests were used for the comparison of means across continuous variables between participants with and without post-TPIAT steatosis. RESULTS: A total of 20 participants (mean: 13 ± 4 years; 12 female) were evaluated. Mean liver PDFF at research MRI was 7.4 ± 6.2% (range: 2-25%). Seven participants (35%) had categorical hepatic steatosis (PDFF>5%) post-TPIAT, five of whom had pre-TPIAT steatosis, reflecting a 13% (2/15; 95% CI: 2-40%) incidence of post-TPIAT steatosis. Participant characteristics were not significantly different between subgroups with and without post-TPIAT steatosis. Mean PDFF at research MRI was not different between graft function subgroups (7.5% optimal/good vs. 7.3% marginal/failure; p = .96). CONCLUSION: Our study shows a moderate prevalence but low incidence of hepatic steatosis in a small sample of children and adolescents post-TPIAT. This study raises questions about a causal relationship between TPIAT and hepatic steatosis.

Changes in Bone Marrow Adipose Tissue in Transgender and Gender Non-Conforming Youth Undergoing Pubertal Suppression: A Pilot Study.

Pubertal suppression with gonadotropin-releasing hormone (GnRH) agonists in transgender and gender non-conforming (TGNC) youth may affect acquisition of peak bone mass. Bone marrow adipose tissue (BMAT) has an inverse relationship with bone mineral density (BMD). To evaluate the effect of pubertal suppression on BMAT, in this pilot study we prospectively studied TGNC youth undergoing pubertal suppression and cisgender control participants with similar pubertal status over a 12-month period. BMD was measured by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Magnetic Resonance T1 relaxometry (T1-R) and spectroscopy (MRS) were performed to quantify BMAT at the distal femur. We compared the change in BMD, T1-R values, and MRS lipid indices between the two groups. Six TGNC (two assigned female and four assigned male at birth) and three female control participants (mean age 10.9 and 11.7 years, respectively) were enrolled. The mean lumbar spine BMD Z-score declined by 0.29 in the TGNC group, but increased by 0.48 in controls (between-group difference 0.77, 95% CI: 0.05, 1.45). Similar findings were observed with the change in trabecular volumetric BMD at the 3% tibia site (-4.1% in TGNC, +3.2% in controls, between-group difference 7.3%, 95% CI: 0.5%-14%). Distal femur T1 values declined (indicative of increased BMAT) by 7.9% in the TGNC group, but increased by 2.1% in controls (between-group difference 10%, 95% CI: -12.7%, 32.6%). Marrow lipid fraction by MRS increased by 8.4% in the TGNC group, but declined by 0.1% in controls (between-group difference 8.5%, 95% CI: -50.2%, 33.0%). In conclusion, we observed lower bone mass acquisition and greater increases in BMAT indices by MRI and MRS in TGNC youth after 12 months of GnRH agonists compared with control participants. Early changes in BMAT may underlie an alteration in bone mass acquisition with pubertal suppression, including alterations in mesenchymal stem cells within marrow.

Quantification of Hepatic Steatosis by Ultrasound: Prospective Comparison With MRI Proton Density Fat Fraction as Reference Standard.

BACKGROUND. Multiple ultrasound platforms now provide quantitative measures of hepatic steatosis. One such measure is the ultrasound-derived fat fraction (UDFF), which combines attenuation and backscatter quantification. OBJECTIVE. The purpose of this study was to characterize agreement between UDFF and MRI proton-density fat fraction (PDFF) measurements. METHODS. This prospective cross-sectional study enrolled 56 overweight and obese adolescents and adults (age ≥ 16 years) who underwent investigational ultrasound (deep abdominal transducer) and MRI examinations of the liver during a single visit from August 2020 to October 2020. Ultrasound examinations included three UDFF acquisitions of five measurements each (15 measurements total), and an overall median of medians was computed (UDFFoverall). MRI examinations included three PDFF acquisitions with calculation of an overall median PDFF. Spearman rank-order correlation was computed between UDFF and MRI PDFF measurements. Intraclass correlation coefficients and Bland-Altman difference plots were used to assess agreement. ROC curves were used to assess diagnostic performance of UDFF for detecting MRI PDFF of 5.5% or more. RESULTS. Median participant age was 32.5 years (IQR, 24.0-39.0 years); 40 participants were female, and 16 were male. A total of 34 (60.7%) participants had an MRI PDFF of 5.5% or more. UDFFoverall was 10.5% (IQR, 5.0-20.0%); median MRI PDFF was 6.1% (IQR, 3.4-13.7%). UDFFoverall was positively associated with MRI PDFF (ρ, 0.82; p < .001; intraclass correlation coefficient, 0.84 [95% CI, 0.59-0.93]). Mean bias between UDFF and PDFF was 4.0% (95% limits of agreement, -7.9% to 15.9%), with similar bias if summarizing UDFF by the first five measurements (4.4%), first three measurements (4.4%), or first measurement (4.6%). UDFFoverall AUC was 0.90 (95% CI, 0.79-0.96) for MRI PDFF of 5.5% or more; AUC was not significantly different when it was based on the number of UDFF measurements (p = .11-.97 for all pairwise AUC comparisons). UDFFoverall cutoff of more than 5% had sensitivity of 94.1% and specificity of 63.6% for diagnosing MRI PDFF of 5.5% or more. CONCLUSION. Measurements of hepatic steatosis using UDFF show strong agreement with measurements by MRI PDFF. A UDFFoverall cutoff of more than 5% provides high AUC and sensitivity, albeit low specificity, for detection of MRI PDFF of 5.5% or more. CLINICAL IMPACT. UDFF may have a clinical role in detection of hepatic steatosis. A reduced number of individual measurements is likely sufficient for determining an overall UDFF value. TRIAL REGISTRATION. ClinicalTrials.gov: NCT04523584.

Bowel wall MRI T1 relaxation estimates for assessment of intestinal inflammation in pediatric Crohn's disease.

PURPOSE: To compare bowel wall T1 relaxation estimates in young patients with newly diagnosed ileal CD to healthy control participants, characterize their change over time in response to biologic medical therapy, and evaluate their associations with clinical markers of intestinal inflammation. MATERIALS AND METHODS: Patients with newly diagnosed ileal CD and healthy control participants were prospectively recruited between December 2018 and October 2021. Patients underwent research MRI examinations of the bowel at baseline and at 6-weeks and 6-months into biologic medical treatment; control participants underwent single MRI examinations. MRI examinations included native T1 relaxometry of the terminal ileum using a modified Look-Locker inversion recovery (MOLLI) sequence. T1 estimates were measured on scanner-generated parametric maps. Clinical markers of intestinal inflammation were recorded at each visit. Group differences were assessed using the Mann-Whitney U test; the Friedman test was used to assess longitudinal changes in T1 estimates. Spearman correlation was used to evaluate associations between T1 estimates and inflammatory markers. RESULTS: Nineteen participants with CD (12 males; median age 14 years) and 15 control participants (7 males; median age 17 years) were included in the study. Bowel wall T1 estimates in CD patients (median 1302 ms) were significantly longer compared to control participants (median 1159 ms) (p < 0.001). In CD patients, T1 estimates changed over time after treatment (p = 0.001), with largest reductions between baseline and 6-weeks (p < 0.001). T1 estimates correlated with inflammatory markers, including erythrocyte sedimentation rate (ρ = 0.35; p = 0.01), c-reactive protein level (ρ = 0.34; p = 0.02), and weighted Pediatric Crohn's Disease Activity Index (ρ = 0.39; p = 0.005). T1 estimates did not correlate with serum albumin (ρ = - 0.28; p = 0.051) and fecal calprotectin (ρ = 0.07; p = 0.63). CONCLUSION: Bowel wall T1 estimates are abnormally increased in newly diagnosed ileal CD patients and decrease in response to medical therapy.

Quantitative cardiopulmonary magnetic resonance imaging in neonatal congenital diaphragmatic hernia.

BACKGROUND: Pulmonary arterial hypertension, impaired cardiac function and lung hypoplasia are common in infants with congenital diaphragmatic hernia (CDH) and are associated with increased morbidity and mortality. Robust noninvasive methods to quantify these abnormalities in early infancy are lacking. OBJECTIVE: To determine the feasibility of MRI to quantify cardiopulmonary hemodynamics and function in infants with CDH and to investigate left-right blood flow and lung volume discrepancies. MATERIALS AND METHODS: We conducted a prospective MRI study of 23 neonates (isolated left CDH: 4 pre-repair, 7 post-repair, 3 pre- and post-repair; and 9 controls) performed on a small-footprint 1.5-tesla (T) scanner. We calculated MRI-based pulmonary arterial blood flow, left ventricular eccentricity index, cardiac function and lung volume. Using the Wilcoxon rank sum test for continuous data and Fisher exact test for categorical data, we made pairwise group comparisons. RESULTS: The right-to-left ratios for pulmonary artery blood flow and lung volume were elevated in pre-repair and post-repair CDH versus controls (flow: P<0.005; volume: P<0.05 pre-/post-repair). Eccentricity index at end-systole significantly differed between pre-repair and post-repair CDH (P<0.01) and between pre-repair CDH and controls (P<0.001). CONCLUSION: Cardiopulmonary MRI is a viable method to serially evaluate cardiopulmonary hemodynamics and function in critically ill infants and is useful for capturing left-right asymmetries in pulmonary blood flow and lung volume.