Effect of maneuvers, diuresis, and fluid administration on ultrasound-measured liver stiffness after Fontan.

BACKGROUND: To determine the effect of stress maneuvers/interventions on ultrasound liver stiffness measurements (LSMs) in patients with Fontan circulation and healthy controls. METHODS: In this prospective, IRB-approved study of 10 patients after Fontan palliation and 10 healthy controls, ultrasound 2D shear-wave elastography LSMs were acquired at baseline and after maximum inspiration, expiration, standing, handgrip, aerobic exercise, i.v. fluid (500 mL normal saline) administration, and i.v. furosemide (20 mg) administration. Absolute and percent change in LSM were compared between baseline and each maneuver, and then from fluid infusion to after diuresis. RESULTS: Median ages were 25.5 and 26 years in the post-Fontan and control groups (p = 0.796). LSMs after Fontan were higher at baseline (2.6 vs. 1.3 m/s) and with all maneuvers compared to controls (all p < 0.001). Changes in LSM with maneuvers, exercise, fluid, or diuresis were not significant when compared to baseline in post-Fontan patients. LSM in controls increased with inspiration (+0.02 m/s, 1.6%, p = 0.03), standing (+0.07 m/s, 5.5%, p = 0.03), and fluid administration (+0.10 m/s, 7.8%, p = 0.002), and decreased 60 minutes after diuretic administration (-0.05 m/s, -3.9%, p = 0.01) compared to baseline. LSM after diuretic administration significantly decreased when compared to after i.v. fluid administration at 30 minutes (-0.79 m/s, -26.5%, p = 0.004) and 60 minutes (-0.78 m/s, -26.2%, p = 0.017) for patients after Fontan and controls at 15 minutes (-0.12 m/s, -8.70%, p = 0.002), 30 minutes (-0.15 m/s, -10.9%, p = 0.003), and 60 minutes (-0.1 m/s, -10.9%, p = 0.005). CONCLUSIONS: LSM after Fontan is higher with more variability compared to controls. Diuresis is associated with significantly decreased liver stiffness in both patients after Fontan and controls, with the suggestion of a greater effect in Fontan patients.

Impact of upgrading from a 25-cm to a 30-cm z-axis field of view digital PET/CT in a pediatric hospital.

BACKGROUND: Increased positron emission tomography (PET) scanner z-axis coverage provides an opportunity in pediatrics to reduce dose, anesthesia, or repeat scans due to motion. OBJECTIVE: Recently, our digital PET scanner was upgraded from a 25-cm to a 30-cm z-axis coverage. We compare the two systems through National Electrical Manufacturing Association (NEMA) testing and evaluation of paired images from patients scanned on both systems. MATERIALS AND METHODS: NEMA testing and a retrospective review of pediatric patients who underwent clinically indicated 18F-fluorodeoxyglucose (FDG) PET computed tomography (PET/CT) on both systems with unchanged acquisition parameters were performed. Image quality was assessed with liver signal to noise ratio (SNR-liver) and contrast to noise ratio (CNR) in the thigh muscle and liver with results compared with an unpaired t-test. Three readers independently reviewed paired (25 cm and 30 cm) images from the same patient, blinded to scanner configuration. RESULTS: Expansion to 30 cm increased system sensitivity to 29.8% (23.4 cps/kBq to 30.4 cps/kBq). Seventeen patients (6 male/11 female, median age 12.5 (IQR 8.3-15.0) years, median weight 53.7 (IQR 34.2-68.7) kg) were included. SNR-liver and CNR increased by 35.1% (IQR 19.0-48.4%) and 43.1% (IQR 6.2-50.2%) (P-value <0.001), respectively. All readers preferred images from the 30-cm configuration. A median of 1 (IQR 1-1) for fewer bed positions was required with the 30-cm configuration allowing a median of 91 (IQR 47-136) s for shorter scans. CONCLUSION: Increasing z-axis coverage from 25 to 30 cm on a current-generation digital PET scanner significantly improved PET system performance and patient image quality, and reduced scan duration.

Impact of Emerging Deep Learning-Based MR Image Reconstruction Algorithms on Abdominal MRI Radiomic Features.

OBJECTIVE: This study aims to evaluate, on one MRI vendor's platform, the impact of deep learning (DL)-based reconstruction techniques on MRI radiomic features compared to conventional image reconstruction techniques. METHODS: Under IRB approval and informed consent, we prospectively collected undersampled coronal T2-weighted MR images of the abdomen (1.5 T; Philips Healthcare) from 17 pediatric and adult subjects and reconstructed them using a conventional image reconstruction technique (compressed sensitivity encoding [C-SENSE]) and two DL-based reconstruction techniques (SmartSpeed [Philips Healthcare, US FDA cleared] and SmartSpeed with Super Resolution [SmartSpeed-SuperRes, not US FDA cleared to date]). Eight regions of interest (ROIs) across organs/tissues (liver, spleen, kidney, pancreas, fat, and muscle) were manually placed. Eighty-six MRI radiomic features were then extracted. Pearson's correlation coefficients (PCCs) and intraclass correlation coefficients (ICCs) were calculated between (A) C-SENSE versus SmartSpeed, and (B) C-SENSE versus SmartSpeed-SuperRes. To quantify the impact from the perspective of the whole MR image, cross-ROI mean PCCs and ICCs were calculated for individual radiomic features. The impact of image reconstruction on individual radiomic features in different organs/tissues was evaluated using ANOVA analyses. RESULTS: According to cross-ROI mean PCCs, 50 out of 86 radiomic features were highly correlated (PCC, ≥0.8) between SmartSpeed and C-SENSE, whereas only 15 radiomic features were highly correlated between SmartSpeed-SuperRes and C-SENSE reconstructions. According to cross-ROI mean ICCs, 58 out of 86 radiomic features had high agreements (ICC ≥0.75) between SmartSpeed and C-SENSE, whereas only 9 radiomic features had high agreements between SmartSpeed-SuperRes and C-SENSE reconstructions. For SmartSpeed reconstruction, the psoas muscle ROI appeared to be impacted most with the lowest median (IQR) correlation of 0.57 (0.25). The circular liver ROI was impacted most by SmartSpeed-SuperRes (PCC, 0.60 [0.22]). ANOVA analyses suggest that the impact of DL reconstruction algorithms on radiomic features varies significantly among different organs/tissues (P < 0.001). CONCLUSIONS: MRI radiomic features are significantly altered by DL-based reconstruction compared to a conventional reconstruction technique. The impact of DL reconstruction algorithms on radiomic features varies significantly between different organs/tissues.

Simultaneous Multiparameter Mapping of the Liver in a Single Breath-Hold or Respiratory-Triggered Acquisition Using Multi-Inversion Spin and Gradient Echo MRI.

BACKGROUND: Quantitative parametric mapping is an increasingly important tool for noninvasive assessment of chronic liver disease. Conventional parametric mapping techniques require multiple breath-held acquisitions and provide limited anatomic coverage. PURPOSE: To investigate a multi-inversion spin and gradient echo (MI-SAGE) technique for simultaneous estimation of T1, T2, and T2* of the liver. STUDY TYPE: Prospective. SUBJECTS: Sixteen research participants, both adult and pediatric (age 17.5 ± 4.6 years, eight male), with and without known liver disease (seven asymptomatic healthy controls, two fibrotic liver disease, five steatotic liver disease, and two fibrotic and steatotic liver disease). FIELD STRENGTH/SEQUENCE: 1.5 T, single breath-hold and respiratory triggered MI-SAGE, breath-hold modified Look-Locker inversion recovery (MOLLI, T1 mapping), breath-hold gradient and spin echo (GRASE, T2 mapping), and multiple gradient echo (mGRE, T2* mapping) sequences. ASSESSMENT: Agreement between hepatic T1, T2, and T2* estimated using MI-SAGE and conventional parametric mapping sequences was evaluated. Repeatability and reproducibility of MI-SAGE were evaluated using a same-session acquisition and second-session acquisition. STATISTICAL TESTS: Bland-Altman analysis with bias assessment and limits of agreement (LOA) and intraclass correlation coefficients (ICC). RESULTS: Hepatic T1, T2, and T2* estimates obtained using the MI-SAGE technique had mean biases of 72 (LOA: -22 to 166) msec, -3 (LOA: -10 to 5) msec, and 2 (LOA: -5 to 8) msec (single breath-hold) and 36 (LOA: -43 to 120) msec, -3 (LOA: -17 to 11) msec, and 4 (LOA: -3 to 11) msec (respiratory triggered), respectively, in comparison to conventional acquisitions using MOLLI, GRASE, and mGRE. All MI-SAGE estimates had strong repeatability and reproducibility (ICC > 0.72). DATA CONCLUSION: Hepatic T1, T2, and T2* estimates obtained using an MI-SAGE technique were comparable to conventional methods, although there was a 12%/6% for breath-hold/respiratory triggered underestimation of T1 values compared to MOLLI. Both respiratory triggered and breath-hold MI-SAGE parameter maps demonstrated strong repeatability and reproducibility. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 2.

T1 Mapping of the Abdomen, From the AJR "How We Do It" Special Series.

By exploiting different tissues' characteristic T1 relaxation times, T1-weighted images help distinguish normal and abnormal tissues, aiding assessment of diffuse and local pathologies. However, such images do not provide quantitative T1 values. Advances in abdominal MRI techniques have enabled measurement of abdominal organs' T1 relaxation times, which can be used to create color-coded quantitative maps. T1 mapping is sensitive to tissue microenvironments including inflammation and fibrosis and has received substantial interest for noninvasive imaging of abdominal organ pathology. In particular, quantitative mapping provides a powerful tool for evaluation of diffuse disease by making apparent changes in T1 occurring across organs that may otherwise be difficult to identify. Quantitative measurement also facilitates sensitive monitoring of longitudinal T1 changes. Increased T1 in liver helps to predict parenchymal fibro-inflammation, in pancreas is associated with reduced exocrine function from chronic or autoimmune pancreatitis, and in kidney is associated with impaired renal function and aids diagnosis of chronic kidney disease. In this review, we describe the acquisition, postprocessing, and analysis of T1 maps in the abdomen and explore applications in liver, spleen, pancreas, and kidney. We highlight practical aspects of implementation and standardization, technical pitfalls and confounding factors, and areas of likely greatest clinical impact.

Rapid abdominopelvic MR imaging in the emergency department: establishing a program and addressing the challenges.

Utilization of magnetic resonance imaging (MRI) in the pediatric emergency room or urgent care setting for abdominopelvic indications has been increasing. The creation and implementation of rapid urgent MRI programs can have various challenges. The purpose of this article is to describe a framework for the creation of a rapid urgent abdominopelvic MRI program in the pediatric emergency room setting.

Normal ovarian sizes on MRI in pediatric patients: a preliminary study.

BACKGROUND: Ovarian enlargement is one of several findings of pathology, including ovarian torsion. With increasing use of MRI for acute abdominal pain in children, data for normal ovary size and appearance are needed. OBJECTIVE: To provide preliminary data on normal sizes of ovaries on MRI in pediatric patients. MATERIALS AND METHODS: This retrospective IRB-approved study included girls (5 to 17 years of age) with MRI examinations performed for indications not related to the ovaries from 2018 to 2022. For each MRI, coronal T2-weighted single shot fast spin echo and axial T2-weighted fat-saturated images were independently reviewed by three pediatric radiologists who recorded ovary visualization and ovarian linear measurements (3 planes). Ovarian volumes were calculated from linear measurements. Agreement among observers was calculated using kappa statistics and intraclass correlation coefficients. RESULTS: A total of 181 MRIs were reviewed. The left ovary was visualized in 166-176 (92-97%) cases (R1-R3) and the right ovary was visualized in 165-174 (91-96%) cases with excellent agreement among reviewers (left: K = 0.89 [0.84-0.94], right: K = 0.85 [0.79-0.91]). Interrater class coefficient (ICC) for largest single dimension of the ovary was left: 0.83 (CI 0.79-0.87) and right: 0.85 (CI 0.81-0.89). There were significant moderate to strong correlations between ovarian volume and age (left: 0.67 [0.58-0.75], right: 0.66 [0.57-0.74]). CONCLUSION: The ovaries can be adequately visualized and measured on MRI with excellent inter-reader agreement. This study serves as the foundation for developing normative values for ovarian volumes by age on MRI.

Semi-automated software improves interrater reliability and reduces processing time of magnetic resonance imaging-based exocrine pancreatic assessments in pediatric patients.

OBJECTIVES: Magnetic resonance (MR) imaging with secretin stimulation (MR-PFTs) is a non-invasive test for pancreatic exocrine function based on assessing the volume of secreted bowel fluid in vivo. Adoption of this methodology in clinical care and research is largely limited to qualitative assessment of secretion as current methods for secretory response quantification require manual thresholding and segmentation of MR images, which can be time-consuming and prone to interrater variability. We describe novel software (PFTquant) that preprocesses and thresholds MR images, performs heuristic detection of non-bowel fluid objects, and provides the user with intuitive semi-automated tools to segment and quantify bowel fluid in a fast and robust manner. We evaluate the performance of this software on a retrospective set of clinical MRIs. METHODS: Twenty MRIs performed in children (< 18 years) were processed independently by two observers using a manual technique and using PFTquant. Interrater agreement in measured secreted fluid volume was compared using intraclass correlation coefficients, Bland-Altman difference analysis, and Dice similarity coefficients. RESULTS: Interrater reliability of measured bowel fluid secretion using PFTquant was 0.90 (0.76-0.96 95% C.I.) with - 4.5 mL mean difference (-39.4-30.4 mL 95% limits of agreement) compared to 0.69 (0.36-0.86 95% C.I.) with - 0.9 mL mean difference (-77.3-75.5 mL 95% limits of agreement) for manual processing. Dice similarity coefficients were better using PFTquant (0.88 +/- 0.06) compared to manual processing (0.85 +/- 0.10) but not significantly (p = 0.11). Time to process was significantly (p < 0.001) faster using PFTquant (412 +/- 177 s) compared to manual processing (645 +/- 305 s). CONCLUSION: Novel software provides fast, reliable quantification of secreted fluid volume in children undergoing MR-PFTs. Use of the novel software could facilitate wider adoption of quantitative MR-PFTs in clinical care and research.

Understanding Provider Cost of MRI for Appendicitis in Children: A Time-Driven Activity-Based Costing Analysis.

OBJECTIVE: To use time driven activity-based costing to characterize the provider cost of rapid MRI for appendicitis compared to other MRI examinations billed with the same Current Procedural Terminology codes commonly used for MRI appendicitis examinations. METHODS: Rapid MRI appendicitis examination was compared with MRI pelvis without intravenous contrast, MRI abdomen/pelvis without intravenous contrast, and MRI abdomen/pelvis with intravenous contrast. Process maps for each examination were created through direct shadowing of patient procedures (n = 20) and feedback from relevant health care professionals. Additional data were collected from the electronic medical record for 327 MRI examinations. Practical capacity cost rates were calculated for personnel, equipment, and facilities. The cost of each step was calculated by multiplying the capacity cost rate with the mean duration of each step. Stepwise costs were summed to generate a total cost for each MRI examination. RESULTS: The mean duration and costs for MRI examination type were as follows: MRI appendicitis: 11 (range: 6-25) min, $20.03 (7.80-44.24); MRI pelvis without intravenous contrast: 55 (29-205) min, $105.99 (64.18-285.13); MRI abdomen/pelvis without intravenous contrast: 65 (26-173) min, $144.83 (61.16-196.50); MRI abdomen/pelvis with intravenous contrast: 128 (39-303) min, $236.99 (102.62-556.54). CONCLUSION: The estimated cost of providing a rapid appendicitis MRI examination is significantly less than other MRI examinations billed using Current Procedural Terminology codes typically used for appendicitis MRI. Mechanisms to appropriately bill rapid MRI examinations with limited sequences are needed to improve cost efficiency for the patient and to enable wider use of limited MRI examinations in the pediatric population.

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.

ACR Appropriateness Criteria® Urinary Tract Infection-Child: 2023 Update.

Urinary tract infection (UTI) is a frequent infection in childhood. The diagnosis is usually made by history and physical examination and confirmed by urine analysis. Cystitis is infection or inflammation confined to the bladder, whereas pyelonephritis is infection or inflammation of kidneys. Pyelonephritis can cause renal scarring, which is the most severe long-term sequela of UTI and can lead to accelerated nephrosclerosis, leading to hypertension and chronic renal failure. The role of imaging is to guide treatment by identifying patients who are at high risk to develop recurrent UTIs or renal scarring. This document provides initial imaging guidelines for children presenting with first febrile UTI with appropriate response to medical management, atypical or recurrent febrile UTI, and follow-up imaging for children with established vesicoureteral reflux. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

ACR Appropriateness Criteria® Soft Tissue Vascular Anomalies: Vascular Malformations and Infantile Vascular Tumors (Non-CNS)-Child.

Soft tissue vascular anomalies may be composed of arterial, venous, and/or lymphatic elements, and diagnosed prenatally or later in childhood or adulthood. They are divided into categories of vascular malformations and vascular tumors. Vascular malformations are further divided into low-flow and fast-flow lesions. A low-flow lesion is most common, with a prevalence of 70%. Vascular tumors may behave in a benign, locally aggressive, borderline, or malignant manner. Infantile hemangioma is a vascular tumor that presents in the neonatal period and then regresses. The presence or multiple skin lesions in an infant can signal underlying visceral vascular anomalies, and complex anomalies may be associated with overgrowth syndromes. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

An International Survey Investigating the Incidence and Management of Brown Fat Uptake on 18F-FDG PET/CT at Children's Hospitals and Interventions for Mitigation.

Brown fat can present challenges in patients with cancer who undergo 18F-FDG PET scans. Uptake of 18F-FDG by brown fat can obscure or appear similar to active oncologic lesions, causing clinical challenges in PET interpretation. Small, retrospective studies have reported environmental and pharmacologic interventions for suppressing brown fat uptake on PET; however, there is no clear consensus on best practices. We sought to characterize practice patterns for strategies to mitigate brown fat uptake of 18F-FDG during PET scanning. Methods: A survey was developed and distributed via e-mail LISTSERV to members of the Children's Oncology Group diagnostic imaging committee, the Society for Nuclear Medicine and Molecular Imaging pediatric imaging council, and the Society of Chiefs of Radiology at Children's Hospitals between April 2022 and February 2023. Responses were stored anonymously in REDCap, aggregated, and summarized using descriptive statistics. Results: Fifty-five complete responses were submitted: 51 (93%) faculty and fellow-level physicians, 2 (4%) technologists, and 2 (4%) respondents not reporting their rank. There were 43 unique institutions represented, including 5 (12%) outside the United States. Thirty-eight of 41 (93%) institutions that responded on environmental interventions reported using warm blankets in the infusion and scanning rooms. Less than a third (n = 13, 30%) of institutions reported use of a pharmacologic intervention, with propranolol (n = 5, 38%) being most common, followed by fentanyl (n = 4, 31%), diazepam (n = 2, 15%), and diazepam plus propranolol (n = 2, 15%). Selection criteria for pharmacologic intervention varied, with the most common criterion being brown fat uptake on a prior scan (n = 6, 45%). Conclusion: Clinical practices to mitigate brown fat uptake on pediatric 18F-FDG PET vary widely. Simple environmental interventions including warm blankets or increasing the temperature of the injection and scanning rooms were not universally reported. Less than a third of institutions use pharmacologic agents for brown fat mitigation.

Visibility and Size of the Pancreatic Duct and Common Bile Duct on Routine 2D MRI Sequences in Children Without Pancreaticobiliary Disease.

BACKGROUND. Pancreatic duct (PD) or common bile duct (CBD) dilatation can indicate ductal pathology, but limited data describe normal pediatric duct measurements on routine 2D MRI sequences. OBJECTIVE. The purpose of this study was to characterize the visibility and diameter of the PD and CBD on 2D MR images in children without pancreaticobiliary disease. METHODS. This retrospective study included patients who underwent abdominal MRI using a rapid protocol (composed of noncontrast axial and coronal 2D SSFSE sequences) to assess for suspected appendicitis or ovarian torsion in the emergency department setting between January 23, 2023, and September 13, 2023, and excluded patients with a pancreatic or hepatobiliary abnormality on MRI or laboratory assessment. Four pediatric radiologists independently reviewed examinations. Reviewers recorded PD visibility in each of four segments (i.e., head, neck, body, and tail) and CBD visibility, and reviewers measured PD diameter in each segment and maximal CBD diameter. Duct measurements by age were characterized by linear regression analyses. RESULTS. The study included 177 patients (112 female patients, 65 male patients; mean age, 12.3 ± 3.4 [SD] years [age range, 5.1-17.7 years]). The observers reported PD visibility in the head in 35.6-94.9% of patients, neck in 18.6-72.3%, body in 22.6-89.8%, and tail in 7.3-26.0% and reported PD visibility in all four segments in 6.2-22.6% of patients. Maximum PD diameter in any segment, as a mean across observers, was 1.8 mm (range across observers, 0.7-3.5 mm). The expected maximal PD diameter in any segment, in terms of the 5th and 95th percentile values of observers' mean measurements, was 1.4-2.3 mm; the prediction interval's upper limit increased from age 5 to age 17 from 2.1 to 2.5 mm. All observers reported CBD visibility in all patients. The mean CBD diameter across observers was 3.1 mm (range across observers, 2.9-3.4 mm). The expected CBD diameter, in terms of the 5th and 95th percentile values of observers' mean measurements, was 2.3-4.9 mm; the prediction interval's upper limit increased from age 5 to age 17 from 3.9 to 5.0 mm. CONCLUSION. We report expected upper limits for PD and CBD measurements on 2D MR images in children without evidence of pancreaticobiliary disease. CLINICAL IMPACT. These findings may aid radiologists' identification of pancreaticobiliary duct abnormalities on routine abdominal MRI examinations.

Deep Learning Models for Abdominal CT Organ Segmentation in Children: Development and Validation in Internal and Heterogeneous Public Datasets.

BACKGROUND. Deep learning abdominal organ segmentation algorithms have shown excellent results in adults; validation in children is sparse. OBJECTIVE. The purpose of this article is to develop and validate deep learning models for liver, spleen, and pancreas segmentation on pediatric CT examinations. METHODS. This retrospective study developed and validated deep learning models for liver, spleen, and pancreas segmentation using 1731 CT examinations (1504 training, 221 testing), derived from three internal institutional pediatric (age ≤ 18 years) datasets (n = 483) and three public datasets comprising pediatric and adult examinations with various pathologies (n = 1248). Three deep learning model architectures (SegResNet, DynUNet, and SwinUNETR) from the Medical Open Network for Artificial Intelligence (MONAI) framework underwent training using native training (NT), relying solely on institutional datasets, and transfer learning (TL), incorporating pretraining on public datasets. For comparison, TotalSegmentator, a publicly available segmentation model, was applied to test data without further training. Segmentation performance was evaluated using mean Dice similarity coefficient (DSC), with manual segmentations as reference. RESULTS. For internal pediatric data, the DSC for TotalSegmentator, NT models, and TL models for normal liver was 0.953, 0.964-0.965, and 0.965-0.966, respectively; for normal spleen, 0.914, 0.942-0.945, and 0.937-0.945; for normal pancreas, 0.733, 0.774-0.785, and 0.775-0.786; and for pancreas with pancreatitis, 0.703, 0.590-0.640, and 0.667-0.711. For public pediatric data, the DSC for TotalSegmentator, NT models, and TL models for liver was 0.952, 0.871-0.908, and 0.941-0.946, respectively; for spleen, 0.905, 0.771-0.827, and 0.897-0.926; and for pancreas, 0.700, 0.577-0.648, and 0.693-0.736. For public primarily adult data, the DSC for TotalSegmentator, NT models, and TL models for liver was 0.991, 0.633-0.750, and 0.926-0.952, respectively; for spleen, 0.983, 0.569-0.604, and 0.923-0.947; and for pancreas, 0.909, 0.148-0.241, and 0.699-0.775. The DynUNet TL model was selected as the best-performing NT or TL model considering DSC values across organs and test datasets and was made available as an open-source MONAI bundle (https://github.com/cchmc-dll/pediatric_abdominal_segmentation_bundle.git). CONCLUSION. TL models trained on heterogeneous public datasets and fine-tuned using institutional pediatric data outperformed internal NT models and Total-Segmentator across internal and external pediatric test data. Segmentation performance was better in liver and spleen than in pancreas. CLINICAL IMPACT. The selected model may be used for various volumetry applications in pediatric imaging.

Partial visualization of appendix on ultrasound: What does it mean in the child with suspected appendicitis?

BACKGROUND: Visualization of the entire appendix, including the tip, is thought, but has not been demonstrated, to be important for exclusion of appendicitis by ultrasound. OBJECTIVE: To determine if incomplete visualization of the appendix has negative clinical ramifications including missed appendicitis. METHODS: Under IRB approval we retrospectively reviewed right lower quadrant ultrasound reports from January 2017 to December 2020 to identify examinations with impressions of full visualization of the normal appendix, non-visualization of the appendix with and without secondary findings of appendicitis, and partial visualization of the appendix. Electronic health records were reviewed for follow-up imaging within 48 h, and surgery with pathology reports (if available). RESULTS: 12,193 examinations were included. 4171 (34.2 %) had full visualization of a normal appendix, 5369 (44.0 %) had non-visualization with no secondary findings, and 234 (1.9 %) had non-visualization with secondary findings, The frequencies of appendicitis in these three groups were 34 (0.8 %), 283 (5.3 %), and 127 (54.3 %) respectively. The appendix was partially visualized in 338 (2.8 %) patients with secondary findings present in 53 (15.6 %). Partial visualization without secondary findings had a similar frequency (4.9 %, 14/285) of appendicitis to non-visualized appendix without secondary findings (p = 0.797) and a higher frequency than full visualization of a normal appendix (p < 0.0001). Partial visualization with secondary findings had similar rates (54.7 %, 29/53) to non-visualized appendix with secondary findings (p = 0.953). CONCLUSION: Partial visualization of the appendix with ultrasound (with and without secondary findings) is associated with similar frequencies of appendicitis as non-visualization of appendix (with and without secondary findings).

Association Between MR Elastography Liver Stiffness and Histologic Liver Fibrosis in Children and Young Adults With Autoimmune Liver Disease.

BACKGROUND. Liver fibrosis is an important clinical endpoint of the progression of autoimmune liver disease (AILD); its monitoring would benefit from noninvasive imaging tools. OBJECTIVE. The purpose of this study was to assess the relationship between MR elastography (MRE) liver stiffness measurements and histologic liver fibrosis, as well as to evaluate the performance of MRE and biochemical-based clinical markers for stratifying histologic liver fibrosis severity, in children and young adults with AILD. METHODS. This retrospective study used an existing institutional registry of children and young adults diagnosed with AILD (primary sclerosing cholangitis [PSC], autoimmune sclerosing cholangitis [ASC], or autoimmune hepatitis [AIH]). The registry was searched to identify patients who underwent both a research abdominal 1.5-T MRI examination that included liver MRE (performed for registry enrollment) and a clinically indicated liver biopsy within 6 months of that examination. MRE used a 2D gradient-recalled echo sequence. One analyst measured mean liver shear stiffness (in kilopascals) for each examination. Laboratory markers of liver fibrosis (aspartate aminotransferase-to-platelet ratio index [APRI] and fibrosis-4 [FIB-4] score) were recorded. For investigational purposes, one pathologist, blinded to clinical and MRI data, determined histologic Metavir liver fibrosis stage. The Spearman rank order correlation coefficient was calculated between MRE liver stiffness and Metavir liver fibrosis stage. ROC analysis was used to evaluate diagnostic performance for identifying advanced fibrosis (i.e., differentiating Metavir F0-F1 from F2-F4 fibrosis), and sensitivity and specificity were calculated using the Youden index. RESULTS. The study included 46 patients (median age, 16.6 years [IQR, 13.7-17.8 years]; 20 female patients, 26 male patients); 12 had PSC, 10 had ASC, and 24 had AIH. Median MRE liver stiffness was 2.9 kPa (IQR, 2.2-4.0 kPa). MRE liver stiffness and Metavir fibrosis stage showed strong positive correlation (ρ = 0.68). For identifying advanced liver fibrosis, MRE liver stiffness had an AUC of 0.81, with sensitivity of 65.4% and specificity of 90.0%; APRI had an AUC of 0.72, with sensitivity of 64.0% and specificity of 80.0%; and FIB-4 score had an AUC of 0.71, with sensitivity of 60.0% and specificity of 85.0%. CONCLUSION. MRE liver stiffness measurements were associated with histologic liver fibrosis severity. CLINICAL IMPACT. The findings support a role for MRE in noninvasive monitoring of liver stiffness, a surrogate for fibrosis, in children and young adults with AILD. TRIAL REGISTRATION. ClinicalTrials.gov NCT03175471.