MRI-based synthetic CT for assessment of the bony elements of the sacroiliac joints in children.

OBJECTIVES: The purpose of this study is to assess the equivalency of MRI-based synthetic CT (sCT) to conventional CT for sacroiliac joint bony morphology assessment in children. METHODS: A prospective study was performed. Children who had (PET-)CT-scan underwent additional MRI. sCT-CT image quality was analyzed by two readers subjectively overall, semi-quantitatively in terms of cortical delineation, joint facet defects, growth plate fusion, ossified nuclei, lumbosacral transitional anomaly, and bony bridges, and quantitatively for disc space height, spinal canal width, and sacral vertebrae width and height. Cohen's kappa and equivalence analyses with Bland-Altman plots were calculated for categorical and continuous measures respectively. RESULTS: Ten patients were included (6 boys; aged 9-16 years; mean age 14 years). Overall sCT image quality was rated good. Semi-quantitative assessment of cortical delineation of sacroiliac joints, bony bridges, and joint facet defects on the right iliac and sacral sides showed perfect agreement. Correlation was good to excellent (kappa 0.615-1) for the presence of lumbosacral transitional anomaly, fusion of sacral growth plates, joint facet defect, and presence of ossified nuclei. sCT-CT measurements were statistically equivalent and within the equivalence margins (-1-1 mm) for intervertebral disc space height and spinal canal width. Intra- and inter-reader reliability was excellent for quantitative assessment (0.806 < ICC < 0.998). For categorical scoring, kappa ranged from substantial to excellent (0.615-1). CONCLUSION: sCT appears to be visually equivalent to CT for the assessment of pediatric sacroiliac joints. sCT may aid in visualizing sacroiliac joints compared to conventional MRI, with the benefit that no ionizing radiation is used, especially important in children. CRITICAL RELEVANCE STATEMENT: MRI-based synthetic CT, a new technique that generates CT-like images without ionizing radiation, appears to be visually equivalent to CT for assessment of normal pediatric sacroiliac joints and can potentially assess structural damage as it clearly depicts bony cortex. KEY POINTS: • MRI-based sCT is a new image technique that can generate CT-like images. • We found that sCT performs similarly to CT in displaying bony structures of pediatric sacroiliac joints. • sCT has already been clinically validated in the sacroiliac joints in adults. • sCT can potentially assess structural damage from erosions or ankylosis as it clearly depicts bony cortex.

Apparent diffusion coefficient values of the white matter in magnetic resonance imaging of the neonatal brain may help predict outcome in congenital cytomegalovirus infection.

BACKGROUND: White matter change is a well-known abnormality in congenital cytomegalovirus (cCMV) infection, but grading remains challenging and clinical relevance unclear. OBJECTIVE: To investigate if quantitative measurement of white matter apparent diffusion coefficient (ADC) values in magnetic resonance imaging (MRI) of the neonatal brain can predict outcome in cCMV. MATERIALS AND METHODS: A retrospective, single-center observational study, including patients with cCMV who had a neonatal brain MRI with diffusion-weighted imaging, was performed between 2007 and 2020. Regions of interest were systematically placed in the white matter on the ADC maps. Two pediatric radiologists independently scored additional brain abnormalities. Outcome measures were neonatal hearing and cognitive and motor development. Statistical analysis included simple and penalized elastic net regression. RESULTS: Neonatal brain MRI was evaluated in 255 patients (median age 21 days, 25-75 percentiles: 14-28 days, 121 male). Gyral abnormalities were noted in nine patients (3.5%), ventriculomegaly in 24 (9.4%), and subependymal cysts in 58 (22.7%). General white matter ADC was significantly higher in patients with neonatal hearing loss and cognitive and motor impairment (P< 0.05). For neonatal hearing loss, simple logistic regression using only general white matter was the best prediction model, with a receiver operating characteristic area under the curve (AUC)=0.76. For cognitive impairment, interacting elastic net regression, including other brain abnormalities and frontoparietal white matter ADC, performed best, with AUC=0.89. For motor impairment, interacting elastic net regression, including other brain abnormalities and deep anterior frontal white matter performed best, with AUC=0.73. CONCLUSION: Neonatal white matter ADC was significantly higher in patients with clinical impairments. Quantitative ADC measurement may be a useful tool for predicting clinical outcome in cCMV.

Implications of isolated white matter abnormalities on neonatal MRI in congenital CMV infection: a prospective single-centre study.

OBJECTIVE: Investigating the clinical implications of isolated white matter abnormalities on neonatal brain MRI in congenital cytomegalovirus (CMV). DESIGN: Prospective, observational. PATIENTS/INTERVENTIONS: Two paediatric radiologists, blinded to clinical data, independently scored the white matter in 286 newborns with congenital CMV. After assessing interobserver variability, mean score was used to categorise white matter (normal, doubtful or abnormal). Patients with other brain abnormalities were excluded. MAIN OUTCOME MEASURES: Hearing and neuromotor evaluation. RESULTS: Cohen's weighted kappa was 0.79 (95% CI 0.73 to 0.84). White matter was normal in 121 patients, doubtful in 62, abnormal in 28. Median clinical follow-up was 12.0 months (IQR 12.0-27.7 months). Neonatal hearing loss occurred in 4/27 patients (14.8%) with abnormal, 1/118 patients (0.8%) with normal and 1/62 patients (1.6%) with doubtful white matter (p<0.01). Impaired cognitive development was seen in 3/27 patients (11.1%) with abnormal, 3/114 patients (2.6%) with normal and 1/59 patients (1.7%) with doubtful white matter (p=0.104). Alberta Infant Motor Scale (AIMS) was below P75 in 21/26 patients (80.8%) with abnormal, 73/114 patients (64.0%) with normal and 36/57 patients (63.2%) with doubtful white matter (p=0.231). In a subgroup of patients with minimal clinical follow-up of 18 months, AIMS score was below P75 in 10/13 patients (76.9%) with abnormal, 13/34 patients (38.2%) with normal and 7/20 patients (35.0%) with doubtful white matter (p<0.05). CONCLUSIONS: Abnormal white matter was associated with neonatal hearing loss and mild, lower motor scores. A tendency towards impaired cognitive development was seen. Patients with doubtful white matter did not show worse clinical outcome.

MRI in pediatric sacroiliitis, what radiologists should know.

MRI is used for early detection of inflammation of sacroiliac joints as it shows active lesions of sacroiliitis long before radiographs show damage to the sacroiliac joints. Early diagnosis of arthritis allows early treatment of inflammation and can help delay disease progression and prevent irreversible damage. Also, early identification of axial involvement in juvenile spondyloarthropathy is crucial, as treatment options are different than for peripheral juvenile spondyloarthropathy. In general, standard sequences used in adults are also applied to children. However, interpreting MR images of pediatric sacroiliac joints is more challenging than in adults, because of normal physiological changes during skeletal maturation, which can simulate disease on MR images. Furthermore, classical definitions of sacroiliitis used in adults, for both active inflammatory and structural lesions, can be difficult to extrapolate to children. The development of reliable pediatric-specific definitions for sacroiliitis is still in active study. Understanding both normal and pathological signal changes in children is important to distinguish physiologic findings from disease and to make a correct diagnosis. In this review, the main imaging characteristics of sacroiliitis on MRI in children and its frequent pitfalls will be illustrated, while also citing some discussion points regarding the scan protocol.

Blurring and Irregularity of the Subchondral Cortex in Pediatric Sacroiliac Joints on T1 Images: Incidence of Normal Findings That Can Mimic Erosions.

OBJECTIVE: To determine prevalence of variations of subchondral bone appearance that may mimic erosions on T1-weighted magnetic resonance imaging (MRI) of pediatric sacroiliac (SI) joints according to age and sex. METHODS: With ethics committee approval and informed consent, SI joint MRIs of 251 children (132 girls), mean age 12.4 years (range 6.1-18.0 years), were obtained in 2 cohorts: 127 children imaged for nonrheumatic reasons, and 124 children with low back pain but no features of sacroiliitis at initial clinical MRI review. MRIs were reviewed by 3 experienced radiologists, blinded from each other, for 3 features of the cortical black line representing the subchondral bone plate on T1-weighted MRI: visibility, blurring, and irregularity. RESULTS: Based on agreement from 2 or more readers, the cortical black line was partially absent in 88.4% of the children, blurred in 34.7%, and irregular in 41.4%. All these features were most common on the iliac side of SI joints and at the first sacral vertebra level. Clearly visualized, sharply delineated SI joints with none of these features were seen in only 8.0% of children, or in 35.1% if we conservatively required agreement of all 3 readers to consider a feature present. There was no significant difference between sexes or cohorts; findings were similar across pediatric age groups. CONCLUSION: Understanding the normal MRI appearance of the developing SI joint is necessary to distinguish physiologic findings from disease. At least two-thirds (65%) of normal pediatric SI joints showed at least 1 feature that is a component of the adult definition of SI joint erosions, risking overdiagnosis of sacroiliitis.

MRI-based synthetic CT of the hip: can it be an alternative to conventional CT in the evaluation of osseous morphology?

OBJECTIVES: MRI is the gold standard for soft tissue evaluation in the hip joint. However, CT is superior to MRI in providing clear visualization of bony morphology. The aim of this study is to test the equivalency of MRI-based synthetic CT to conventional CT in quantitatively assessing bony morphology of the hip. MATERIALS AND METHODS: A prospective study was performed. Adult patients who underwent MRI and CT of the hips were included. Synthetic CT images were generated from MRI using a deep learning-based image synthesis method. Two readers independently performed clinically relevant measurements for hip morphology, including anterior and posterior acetabular sector angle, acetabular version angle, joint space width, lateral center-edge angle, sharp angle, alpha angle, and femoral head-neck offset on synthetic CT and CT. Inter-method, inter-reader, and intra-reader reliability and agreement were assessed using calculations of intraclass correlation coefficient, standard error of measurement, and smallest detectable change. The equivalency among CT and synthetic CT was evaluated using equivalency statistical testing. RESULTS: Fifty-four hips from twenty-seven participants were included. There was no reported hip pathology in the subjects. The observed agreement based on reliability and agreement parameters indicated a strong degree of concordance between CT and synthetic CT. Equivalence statistical testing showed that all synthetic CT measurements are equivalent to the CT measurements at the considered margins. CONCLUSION: In healthy individuals, we demonstrated equivalency of MRI-based synthetic CT to conventional CT for the quantitative evaluation of osseous hip morphology, thus obviating the radiation exposure of a pelvic CT examination. KEY POINTS: •MRI-based synthetic CT images can be generated from MRI using a deep learning-based image synthesis method. •MRI-based synthetic CT is equivalent to CT in the quantitative assessment of bony hip morphology in healthy individuals. •MRI-based synthetic CT is promising for use in preoperative diagnosis and surgery planning.

MR Imaging of Rheumatic Diseases Affecting the Pediatric Population.

This article reviews the application of magnetic resonance imaging (MRI) to pediatric rheumatic diseases. MRI can detect early manifestations of arthritis, evaluate the extent of disease, and monitor disease activity and response to treatment.Juvenile idiopathic arthritis (JIA) is the most common pediatric rheumatic disorder, representing a diverse group of related diseases that share a definition of joint inflammation of unknown origin with onset before 16 years of age and lasting > 6 weeks. JIA may lead to significant functional impairment and is increasingly imaged with MRI to assess for active inflammation as a target for therapy. This is particularly true for juvenile spondyloarthritis that includes multiple subgroups of JIA and primarily involves the spine and sacroiliac joints.Other less common pediatric rheumatic diseases considered here are chronic recurrent multifocal osteomyelitis and collagen vascular diseases including polymyositis, dermatomyositis, scleroderma, and juvenile systemic lupus erythematosus.

Brain MRI findings in newborns with congenital cytomegalovirus infection: results from a large cohort study.

OBJECTIVE: To investigate the spectrum and frequency of abnormalities on brain MRI in a large cohort of live newborns with congenital CMV (cCMV) infection. METHODS: Institutional review board approval and informed consent for neonatal MRI and data collection were obtained. Between January 2010 and January 2018, brain MRI was performed in 196 live newborns diagnosed with cCMV. Images were independently reviewed by 2 pediatric radiologists, blinded to clinical data. RESULTS: cCMV infection was clinically symptomatic in 26/191 newborns (13.6%). Brain MRI showed abnormalities in 76/196 patients (38.8%). MRI was abnormal in 20/26 clinically symptomatic patients (76.9%): 76.9% showed white matter lesions, 61.5% subependymal cysts, 46.2% ventriculomegaly, 26.9% ventricular adhesions, 26.9% gyral abnormalities, 24.0% calcifications, 15.4% cerebellar anomalies. MRI was abnormal in 55/165 (33.3%) clinically asymptomatic patients: 30.9% had white matter lesions, 15.8% subependymal cysts, 4.2% ventriculomegaly, 2.4% ventricular adhesions, 1.2% gyral abnormalities, 0.6% calcifications, none had cerebellar anomalies. Concomitant brain lesions were seen in all patients with gyral abnormalities, cerebellar anomalies, and calcifications and nearly all patients with subependymal cysts and ventriculomegaly. In all but 4 patients with other detected brain lesions, white matter abnormalities were simultaneously present. In 33/74 patients (45.2%), white matter lesions were seen as a sole abnormality. CONCLUSION: White matter lesions were the most common detected abnormality on brain MRI in newborns with congenital CMV. Since brain abnormalities were seen in more than 30% of clinically asymptomatic and 75% of clinically symptomatic newborns, MRI should be advised in all newborns diagnosed with cCMV. KEY POINTS: • Neonatal brain MRI showed abnormalities in more than 30% of clinically asymptomatic and 75% of symptomatic newborns with congenital cytomegalovirus infection. • White matter lesions were by far the most common detected abnormality, followed by subependymal cysts and ventricular dilatation. • Lesions in cCMV were often multiple, with many patients showing concomitant lesions.

A synchronous papillary and follicular thyroid carcinoma presenting as a large toxic nodule in a female adolescent.

CASE PRESENTATION: We report for the first time a synchronous papillary and follicular thyroid carcinoma in a 12-year-old girl presenting with a large (5 cm diameter) left thyroid nodule, an increased left and right upper pole technetium tracer uptake at scintigraphy and hyperthyroidism. The uptake at the right lobe was explained by the crossing of the left nodule to the right site of the neck at Computed Tomography (CT) scanning. BACKGROUND: Although thyroid nodules are less common in children than in adults, there is more vigilance required in children because of the higher risk of malignancy. According to literature, about 5% of the thyroid nodules in adults are malignant versus 20-26% in children. The characteristics of 9 other pediatric cases with a differentiated thyroid carcinoma presenting with a toxic nodule, which have been reported during the last 20 years, are summarized. A nodular size of more than 3.5 cm and female predominance was a common finding. CONCLUSIONS: The presence of hyperthyroidism in association with a hyperfunctioning thyroid nodule does not rule out thyroid cancer and warrants careful evaluation, even in the absence of cervical lymph node invasion.