Doppler Ultrasound and Resistive Indices in the Diagnosis of Ureteropelvic Junction Obstruction in the Pediatric Population.

OBJECTIVES: Mercapto acetyl tri-glycine renogram (MAG3) scan has been the gold standard assessment of pediatric ureteropelvic junction obstruction (UPJO) but requires intravenous access and radiation exposure. While Doppler ultrasound measurements of resistive indices (RI) of the arcuate arteries have been proposed as an alternative assessment of obstruction, they have not been widely adopted in the pediatric population. We hypothesized that RI of the main renal artery (RA) is more strongly correlated with MAG3 findings than arcuate RI. METHODS: Pediatric patients with unilateral Society for Fetal Urology grade 3-4 hydronephrosis undergoing concomitant RUS and MAG3 were recruited. Doppler ultrasound peak systolic velocity (PSV); RI of bilateral RA at the origin, middle, and hilum; and RI of the superior, middle, and lower pole arcuate arteries were obtained. MAG3 differential renal function (DRF) and T½ were recorded. Differences in RI measurements (DRI) between the affected and normal kidney were calculated and compared with DRF and T½. RESULTS: 31 patients (median 4.6-month-old) were enrolled. Only RA RI at the origin differed between affected and normal kidneys (p < .001). DRI RA at the origin showed weak evidence for an association with MAG3 DRF < 40% (p .07). DRI was not associated with T½ > 20 minutes. CONCLUSION: There was weak evidence for an association between RA DRI at the origin and DRF but not with T½. These findings suggest that RA DRI may provide additional data in the evaluation of patients with UPJO to tailor the use of MAG3 and associated risk of radiation exposure to those patients most at risk for concomitant renal function impairment.

Reference Values for Fetal Cardiac Dimensions, Volumes, Ventricular Function and Left Ventricular Longitudinal Strain Using Doppler Ultrasound Gated Cardiac Magnetic Resonance Imaging in Healthy Third Trimester Fetuses.

BACKGROUND: Recent advances in hardware and software permit the use of cardiac MRI of late gestation fetuses, however there is a paucity of MRI-based reference values. PURPOSE: To provide initial data on fetal cardiac MRI-derived cardiac dimensions, volumes, ventricular function, and left ventricular longitudinal strain in healthy developing fetuses >30 weeks gestational age. STUDY TYPE: Prospective. POPULATION: Twenty-five third trimester (34 ± 1 weeks, range of 32-37 weeks gestation) women with healthy developing fetuses. FIELD STRENGTH/SEQUENCE: Studies were performed at 1.5 T and 3 T. Cardiac synchronization was achieved with a Doppler ultrasound device. The protocol included T2 single shot turbo spin echo stacks for fetal weight and ultrasound probe positioning, and multiplanar multi-slice cine balanced steady state free precession gradient echo sequences. ASSESSMENT: Primary analyses were performed by a single observer. Weight indexed right ventricular (RV) and left ventricular (LV) volumes and function were calculated from short axis (SAX) stacks. Cardiac dimensions were calculated from the four-chamber and SAX stacks. Single plane LV longitudinal strain was calculated from the four-chamber stack. Interobserver variability was assessed in 10 participants. Cardiac MRI values were compared against available published normative fetal echocardiogram data using z-scores. STATISTICAL TESTS: Mean and SDs were calculated for baseline maternal/fetal demographics, cardiac dimensions, volumes, ventricular function, and left ventricular longitudinal strain. Bland-Altman and intraclass correlation coefficient analysis was performed to test interobserver variability. RESULTS: The mean gestational age was 34 ± 1.4 weeks. The mean RV and LV end diastolic volumes were 3.1 ± 0.6 mL/kg and 2.4 ± 0.5 mL/kg respectively. The mean RV cardiac output was 198 ± 49 mL/min/kg while the mean LV cardiac output was 173 ± 43 mL/min/kg. DATA CONCLUSION: This paper reports initial reference values obtained by cardiac MRI in healthy developing third trimester fetuses. MRI generally resulted in slightly larger indexed values (by z-score) compared to reports in literature using fetal echocardiography. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.

Five siblings expand the spectrum of GPC6-related skeletal dysplasia.

Skeletal dysplasias broadly include disorders of cartilage or bone. Omodysplasia-1 is a type of skeletal dysplasia caused by biallelic loss of function variants in the GPC6 gene. GPC6 codes for the protein glypican 6 (GPC6) (OMIM *604404), which stimulates bone growth. We report a family in which five out of nine children were presented with a skeletal dysplasia characterized phenotypically by mild short stature and rhizomelia. All affected individuals were found to have homozygous missense variants in GPC6: c.511 C>T (p.Arg171Trp). Radiograph findings included rhizomelic foreshortening of all four extremities, coxa breva, and ulna minus deformity. Using a Hedgehog (Hh) reporter assay, we demonstrate that the variant found in this family results in significantly reduced stimulation of Hh activity when compared to the wild-type GPC6 protein, however protein function is still present. Thus, the milder phenotype seen in the family presented is hypothesized due to decreased GPC6 protein activity versus complete loss of function as seen in omodysplasia-1. Given the unique phenotype and molecular mechanism, we propose that this family's findings widen the phenotypic spectrum of GPC6-related skeletal dysplasias.

Fetal lung volumes measured by MRI predict pulmonary morbidity among infants with giant omphaloceles.

OBJECTIVE: Giant omphaloceles (GO) have associated pulmonary hypoplasia and respiratory complications. Total lung volumes (TLV) on fetal MRI can prognosticate congenital diaphragmatic hernia outcomes; however, its applicability to GO is unknown. We hypothesize that late gestation TLV and observed-to-expected TLV (O/E TLV) on fetal MRI correlate with postnatal pulmonary morbidity in GO. METHOD: A single-institution retrospective review of GO evaluated between 2012 and 2022 was performed. Fetal MRI TLV between 32 and 36 weeks' gestation and O/E TLV throughout gestation were calculated and correlated with postnatal outcomes. RESULTS: 86 fetuses with omphaloceles were evaluated; however, only 26 met strict inclusion criteria. MRIs occurred between 18 and 36 weeks' gestation. Those requiring delivery room intubation had significantly lower late gestation TLV and O/E TLV. O/E TLV predicted tracheostomy placement and survival. Neither TLV nor O/E TLV predicted the length of hospitalization or supplemental oxygen after discharge. Three fetuses had a TLV less than 35 mL: one died of respiratory failure, and the other two required tracheostomy. CONCLUSIONS: Fetal MRI TLV measured between 32 and 36 weeks' gestation and O/E TLV predict the need for delivery room intubation and tracheostomy. O/E TLV correlated with survival. These data support fetal MRI as a prognostic tool to predict GO associated pulmonary morbidity.

Third-trimester percentage predicted lung volume and percentage liver herniation as prognostic indicators in congenital diaphragmatic hernia.

BACKGROUND: Over the last two decades, fetal imaging has greatly improved, and new prenatal imaging measurements have been developed to characterize congenital diaphragmatic hernia (CDH) severity. OBJECTIVE: To determine the best prenatal imaging predictor of postnatal CDH outcomes, including use of extracorporeal membrane oxygenation (ECMO) and in-hospital mortality, with particular attention to the percentage of liver herniation (%LH) as a predictor. Additionally, we sought to guide best practices across hospital systems including improved models of prenatal risk assessment. MATERIALS AND METHODS: We conducted a retrospective review of infants with left CDH who were prenatally diagnosed. We analyzed prenatal imaging measurements including observed-to-expected (O/E) lung-to-head ratio (LHR) on US, percentage predicted lung volume (PPLV) on MRI, and O/E total fetal lung volume (TFLV) and %LH on MRI. We compared prenatal imaging characteristics for infants with (1) in-hospital postnatal mortality and (2) use of ECMO. Then we performed multivariate logistic regression to determine independent predictors of postnatal outcomes. RESULTS: We included 63 infants with a median gestation of 34 weeks at the time of prenatal MRI. Low O/E LHR (31.2 vs. 50, P < 0.0001), PPLV (14.7 vs. 22.6, P < 0.0001) and O/E TLFV (24.6 vs. 38.3, P < 0.0001) and high %LH (15.1 vs. 2.1, P = 0.0006) were associated with worse postnatal outcomes; however, only PPLV was predictive of survival and need for ECMO on multivariable analysis. PPLV survival to discharge model showed an area under the curve (AUC) of 0.93 (95% confidence interval [CI]: 0.86, 0.99), P < 0.0001; and an odds ratio of 68.7 (95% CI: 6.5-2,302), P = 0.003. PPLV need for ECMO model showed AUC = 0.87 (95% CI: 0.78, 0.96), P < 0.0001; and odds ratio = 20.1 (95% CI: 3.1-226.3), P = 0.011. CONCLUSION: Low O/E LHR, PPLV and O/E TFLV and high %LH in the third trimester are associated with worse postnatal outcomes. PPLV most strongly predicted outcome using a logistic regression model. Percentage of liver herniation was not an independent predictor of outcomes.

Visualization of the Anal Dimple by Fetal MRI: Is It Feasible?

INTRODUCTION: The aim of this study was to determine the feasibility of fetal MRI in identifying the normal anal dimple (AD) and compare it with prenatal ultrasound (US). METHODS: Retrospective review of 130 patients with both fetal MRI and US. The gestational age (GA) was stratified into four groups: (1) 16 to 21 weeks-6 days; (2) 22 to 27 weeks-6 days; (3) 28 to 33 weeks-6 days; and (4) 34 weeks and beyond. Steady-state free precession (SSFP) and single shot fast spin echo (SSFSE) axial T2 MRI and transverse US images of the fetal perineum were analyzed, and visualization of the AD was determined. Clinical indication, gender, single versus multiple gestation, best MRI sequence where it was seen, and postnatal AD information were recorded. RESULTS: The AD was visualized in 125/130 fetal MRIs, and visualization was independent of GA (p 0.230). US visualized the AD in 67/130 cases, and the best GA for visualization was in group 3 (p < 0.001). There was no difference in AD visualization between SSFSE and SSFP sequences (p 0.167). CONCLUSION: Prenatal visualization of the AD by MRI is feasible and superior to US, independent of GA. Adding AD visualization to routine screening prenatal US and MRI may increase recognition of anorectal malformation.

The novel fetal MRI O/E CLV versus O/E LHR in predicting prognosis in congenital diaphragmatic hernias: can we teach an old dog new tricks?

PURPOSE: In congenital diaphragmatic hernia (CDH), ultrasound (U/S) measurements of the contralateral lung commonly provide the observed-to-expected lung-to-head ratio (O/E LHR) and are used to determine the severity of pulmonary hypoplasia. Fetal magnetic resonance imaging (MRI) measurement of the observed-to-expected total lung volume (O/E TLV) has been used as an adjunct to O/E LHR in predicting outcomes. Since O/E LHR only measures the contralateral lung, we sought to investigate if MRI measurements of the contralateral lung volume (O/E CLV) can accurately predict outcomes in CDH. We hypothesize that O/E CLV is a better predictor of CDH outcomes than O/E LHR. METHODS: We identified all infants with a prenatal diagnosis of CDH at our fetal center who had both MRI and U/S measurements. Using lung volume ratios of right-left 55:45, we calculated O/E CLV from O/E TLV. We used receiver-operating characteristic (ROC) curves to calculate the area under the curve (AUC) to compare the predictive accuracy of O/E CLV to O/E LHR for ECMO support, as well as survival to both discharge and 1 year. RESULTS: Seventy-four patients had complete prenatal imaging with 39% requiring ECMO support. The median O/E CLV was 48.0% and the median O/E LHR was 42.3%. O/E CLV was a better predictor of the need for ECMO support (AUC 0.81 vs. 0.74). O/E CLV was a better predictor of survival to discharge (AUC 0.84 vs. 0.64) and 1-year survival (AUC 0.83 vs. 0.63) than O/E LHR. CONCLUSION: O/E LHR is a well-validated standard for predicting outcomes and guiding prenatal counseling in CDH. We provide evidence that fetal MRI measurements of the contralateral lung volume corrected for gestational age were more accurate in predicting the need for ECMO and survival. Future prospective studies validating O/E CLV regarding outcomes and ECMO utilization are warranted. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Visualization of the fetal anus by prenatal ultrasound for the diagnosis of anorectal malformations: is it feasible?

PURPOSE: The goal of this study was to determine the feasibility of identifying the anal dimple (AD) on routine prenatal ultrasound. Using the presence, absence, appearance, and location of the anal dimple as an indirect sign for possible underlying anorectal malformations (ARM), we hypothesize that evaluation of the anal dimple as part of the fetal anatomic survey may increase the sensitivity in detecting less severe ARMs. METHODS: In a prospective longitudinal observational study, pregnant women who underwent prenatal ultrasound (US) at the Colorado Fetal Care Center between January 2019 and 2020 were enrolled. The variables recorded included gestational age, singleton versus multiple pregnancy, gender of the fetus, visualization of the AD, and reason for non-visualization of the AD. RESULTS: A total of 900 ultrasounds were performed, evaluating 1044 fetuses, in 372 different pregnant women. Gestational ages ranged from 16 to 38 weeks. The AD was visualized in 612 fetuses (58.6%) and not seen in 432 (41.4%). The two most common reasons for non-visualization were extremes in gestational age (n = 155; 36%) and fetal position (n = 152; 35.3%). The optimal gestational age range for AD visualization was 28-33 weeks + 6 days, with 78.1% visualization rate. CONCLUSION: Visualization of the anal dimple by ultrasound is feasible and may aid in the detection of less severe ARMs, ultimately impacting pregnancy management and family counseling. The optimal timing for anal dimple visualization is late second and third trimester.

Placental magnetic resonance imaging Part I: the normal placenta.

Mounting evidence suggests that the placenta is involved in nearly all abnormalities of pregnancy and fetal development. Traditional imaging evaluation of the placenta by ultrasound has more recently been complemented by MRI for complex cases requiring additional information, such as in the diagnosis of the placenta accreta spectrum (placenta accreta, increta and percreta). MRI can often help delineate the safest approach to delivery and adds diagnostic certainty to enable prognostication and to avoid potentially lethal complications. Increasingly, prenatal MRI has become the purview of the pediatric imager and is becoming the standard of care for select gestational indications. However, placental MRI might be unfamiliar to the radiologist. Thus, we provide a simple and systematic approach to evaluating the placenta by MRI, to enable delivery planning and family counseling.

Placental magnetic resonance imaging Part II: placenta accreta spectrum.

The human placenta remains an enigma to many. Its position as the point of communication between distinct maternal and fetal circulations means that it must act as both source of nourishment and gatekeeper for the developing pregnancy. In vivo assessment of the placenta is perhaps the greatest challenge, yet it is most essential for diagnostic and prognostic purposes. In particular, there is a need for improved diagnostic accuracy in recognizing the invasive forms of the placenta accreta spectrum that require surgical intervention at delivery and often cesarean hysterectomy. The costs of insufficient sensitivity and specificity are high, with well-documented cases of adverse outcomes ranging from unnecessary surgery to maternal hemorrhage and even death. In Part I of this pictorial essay series, we reviewed the appearance of the normal developing placenta across gestation by MRI. With this as a background, we here consider the varied appearances of the placenta accreta spectrum (placenta accreta, increta, percreta), which is a growing challenge given the rapidly expanding number of women worldwide with history of cesarean section delivery. Accurate prenatal imaging is crucial for recognizing cases of the placenta accreta spectrum and for planning the necessary surgery.

Imaging of fetal cystic kidney disease: multicystic dysplastic kidney versus renal cystic dysplasia.

With the advent of routine prenatal imaging, the number of renal anomalies identified prenatally has significantly increased; however, the underlying etiologies of these anomalies and the clinical significance of these findings remains unclear. This confusion is especially true for the prenatal diagnosis of cystic renal changes. The terms "cystic kidney disease" and "renal cystic dysplasia" encompass myriad renal diseases. Although renal cystic dysplasia in infants shares many similarities with multicystic dysplastic kidney (MCDK), it is important to distinguish MCDK from other etiologies that would lead to renal cysts, to ensure proper patient diagnosis and appropriate counseling regarding risks and to guide clinical management. The purpose of this review is to highlight the multiple etiologies of cystic kidney disease, including genetic associations, associations with underlying syndromes, and associations with underlying anatomical abnormalities. Here we focus on prenatal imaging, associated pathological findings, and clinical significance, with an emphasis on the defining characteristics of MCDK as compared to other forms of cystic renal disease.

Correction to: The spectrum of cloacal malformations: how to differentiate each entity prenatally with fetal MRI.

The published version of this article unfortunately contained a mistake. Author name Mariana Z. Meyers was incorrect. The correct middle initial is given above.

Differentiating presacral masses in anorectal malformations and isolated sacrococcygeal teratomas.

PURPOSE: Presacral masses associated with anorectal malformations (ARM) are most frequently dermoid or teratomas. Sacrococcygeal teratoma (SCT), in isolation, is a different condition. There are limited data comparing the two. The aim of this study was to compare presacral masses associated with ARM and isolated SCTs. METHODS: A retrospective review was performed from 1979 to 2018. Patients with presacral masses and associated ARM (n = 39) were identified and compared to patients with isolated SCTs (n = 32). RESULTS: Those with presacral mass and ARM had a lower proportion of immature and mixed teratomas by pathology and a longer time to mass resection. They had higher percentages of sacral anomalies (76% versus 9%), tethered cord (50% versus 6%), and other anomalies (51% versus 9%). For long-term bowel function, patients with presacral mass and ARM were more likely to be fecally incontinent and require enemas (59% versus 11%). Regarding isolated SCTs, 4% recurred with a time to recurrence of 7 months. CONCLUSIONS: Compared to patients with isolated SCT, patients with presacral mass and ARM had lower grade tumors. In addition, they had a higher proportion of sacral defects and other congenital defects, as well as worse bowel function outcomes.

Initial Imaging for Pediatric Renal Tumors: An Opportunity for Improvement.

PURPOSE: Current Children's Oncology Group studies on renal malignancy focus on minimizing treatment side effects with a goal of decreasing long-term complications. In this series we evaluate the patterns of initial imaging in children with renal tumors. MATERIALS AND METHODS: We retrospectively reviewed records of 122 patients treated for renal tumors at our institution between 2005 and 2016. Ideal imaging was defined as cross-sectional imaging of the chest, abdomen and pelvis in a single setting without any additional ionizing radiation exposing scans. RESULTS: Median patient age was 33.5 months (range 1 to 195). A total of 101 patients (83%) were initially evaluated elsewhere and subsequently referred to oncology (67.2%) for further evaluation. Before treatment 58 patients (47.5%) underwent imaging that was obtained in an ideal manner. Compared to those undergoing ideal imaging, median additional radiation exposure was 2.31 mSv (range 0.9 to 11.5), 3.08 mSv (0.6 to 11.7) and 5.1 mSv (1.2 to 16) in patients younger than 5 years, 5 to 9 years old and 10 years or older, respectively. Factors associated with undergoing ideal imaging included undergoing abdominal ultrasound as an initial scan (OR 3.637, p = 0.001), while presentation to an emergency department resulted in a reduced likelihood of undergoing ideal imaging (OR 0.351, p = 0.012). Factors associated with a decreased likelihood of undergoing initial screening ultrasound included presenting with vague symptoms (OR 0.072, p = 0.045) and presenting to a tertiary care emergency department (OR 0.228, p = 0.027). CONCLUSIONS: Current patterns of initial imaging for pediatric renal tumors are often associated with unnecessary and avoidable imaging studies, resulting in increased radiation exposure. Presenting to the emergency room as the initial point of contact with vague symptoms is associated with a decreased likelihood of undergoing appropriate or ideal pretherapy imaging, while initial evaluation with ultrasound is associated with a greater likelihood of undergoing ideal imaging, reducing overall radiation exposure. We advocate initial abdominal ultrasound in all pediatric patients suspected of having an abdominal mass. Our data highlight an opportunity for quality improvement across specialties caring for children with renal tumors.

Can a Modified Bosniak Classification System Risk Stratify Pediatric Cystic Renal Masses?

PURPOSE: We characterize and apply the modified Bosniak classification system to a cohort of children with cystic renal lesions and known surgical pathology. MATERIALS AND METHODS: We identified all patients at our institution with cystic renal masses who also underwent surgery for these lesions. Patients without available preoperative imaging or pathology were excluded. All radiological imaging was independently reviewed by a pediatric radiologist blinded to pathological findings. Imaging characteristics (size, border, septations, calcifications, solid components, vascularity) were recorded from the most recent preoperative ultrasounds and computerized tomograms. The modified Bosniak classification system was applied to these scans and then correlated with final pathology. RESULTS: A total of 22 patients met study criteria. Median age at surgery was 6.1 years (range 11 months to 16.8 years). Of the patients 12 (54.5%) underwent open nephrectomy, 6 (27.3%) open partial nephrectomy, 2 (9.1%) laparoscopic cyst decortication, 1 (4.5%) open renal biopsy and 1 (4.5%) laparoscopic partial nephrectomy. Final pathology was benign in 9 cases (41%), intermediate in 6 (27%) and malignant in 7 (32%). All malignant lesions were modified Bosniak class 4, all intermediate lesions were modified class 3 or 4 and 8 of 9 benign lesions (89%) were modified class 1 or 2. CONCLUSIONS: Cystic renal lesions in children with a modified Bosniak class of 1 or 2 were most often benign, while class 3 or 4 lesions warranted surgical excision since more than 90% of masses harbored intermediate or malignant pathology. The modified Bosniak classification system appears to allow for a reasonable clinical risk stratification of pediatric cystic renal masses.

Assessment of Carina Position Antenatally and Postnatally in Infants with Congenital Diaphragmatic Hernia.

OBJECTIVE: To determine whether endotracheal tube (ETT) insertion depth should be modified in infants with congenital diaphragmatic hernia (CDH) to reduce the risk of main-stem intubation. STUDY DESIGN: The distance from the thoracic inlet to the carina was measured antenatally by fetal magnetic resonance imaging (MRI) between 20-28 weeks' (early) and 30-34 weeks' (late) gestation in 30 infants with CDH and compared with 12 early and 36 late MRIs in control infants without CDH. Postnatal tube position was assessed by chest radiograph in the same 30 infants with CDH and compared with 20 control infants with postnatal birth depression. RESULTS: The carina position was displaced upward in fetuses and newborns with CDH. Distance from the thoracic inlet to the carina compared with controls was 1.04 ± 0.1 cm vs 1.42 ± 0.07 cm on early MRI (P < .05), 1.43 ± 0.14 cm vs 1.9 ± 0.04 cm on late MRI (P < .01), and 2.36 ± 0.07 cm vs 3.28 ± 0.05 cm on postnatal radiographs (P < .01). Adjusting the ETT depth by 1 cm resulted in a median distance of 1.27 cm from the tip of the ETT to the carina. CONCLUSION: Cephalad displacement of the carina in infants with CDH may predispose them to right main-stem intubation and subsequent development of pneumothorax. We speculate that modifying the ETT insertion depth to 5.5 cm + weight in newborns born at term may prevent pneumothoraces and improve outcomes for infants with CDH.

Fetal Lung Volumes by MRI: Normal Weekly Values From 18 Through 38 Weeks' Gestation.

OBJECTIVE: The purpose of this study is to establish normal total fetal lung volume reference ranges from 18 to 38 weeks' gestation at 1-week intervals. MATERIALS AND METHODS: A retrospective analysis of 665 patients who underwent fetal MRI at two tertiary fetal centers from 2001 to 2013 was performed. Total fetal lung volume was measured in at least two planes, either manually or using a 3D workstation. The mean, median, SD, minimum, maximum, and lower and upper quartiles for total fetal lung volume were determined per gestational week. A t test was used to compare our values to previously reported values. A new formula to calculate total fetal lung volume derived from our data was created using a regression model. Comparisons between total fetal lung volume obtained by different imaging planes and manual versus semiautomatic calculation were also performed. RESULTS: The mean normal total fetal lung volume showed a weekly increase from 18 through 35 weeks' gestation. Means were compared with the expected total fetal lung volume generated by the Rypens formula, showing statistically significant lower mean total fetal lung volume from week 19 to week 22 (p < 0.05). Comparison between our data-derived total fetal lung volume formula and the Rypens formula showed very similar values at every gestational age. No difference in total fetal lung volume was seen when comparing imaging planes or manual versus semiautomatic methods. CONCLUSION: Measured mean total fetal lung volume values at 19-22 weeks are significantly lower than those predicted by the Rypens formula. Therefore, we propose preferential use of our values for prenatal counseling and delivery planning.

Imaging of congenital central nervous system infections.

Congenital central nervous system (CNS) infections are a cause of significant morbidity and mortality. The recent Zika virus outbreak raised awareness of congenital CNS infections. Imaging can be effective in diagnosing the presence and severity of infection. In this paper we review the clinical presentations and imaging characteristics of several common and less common congenital CNS infections.

Normal Percentile Reference Curves and Correlation of Acetabular Index and Acetabular Depth Ratio in Children.

BACKGROUND: Radiographic surveillance of the hip is vital in the diagnosis and treatment of developmental dysplasia of the hip (DDH) in children. The acetabular index (AI) and the acetabular depth ratio (ADR) are radiographic parameters for evaluation of acetabular morphology. Normal reference curves for these parameters that allow for serial evaluation of acetabular development in a manner that is independent of age are necessary and clinically useful. The purpose of this study was (1) to establish normal values of AI and ADR in the normally developing pediatric hip up to age 14, (2) to generate percentile reference curves of both parameters, (3) to determine the extent of correlation between AI and ADR, and (4) to assess intrarater and interrater reliability of AI measurement. METHODS: We identified 1734 patients who underwent anterior-posterior pelvic radiography between 2004 and 2014. A total of 1152 patients (age range, 0.15 to 13.97 y; 2304 hips) were identified as radiographically normal in the radiology report, signed by the attending pediatric radiologist on the basis of the absence of structural deformity of the hip and previously established reference values for DDH assessment. A review of the medical records confirmed that patients had no diagnosis of DDH or any other orthopaedic hip pathology. The AI and ADR were measured in all radiographs. Normal values and fully parametric percentile curves were generated from birth to skeletal maturity. Correlation between AI and ADR was assessed using linear regression analysis. RESULTS: Normal AI decreased, and ADR increased, with age. Percentile curves were generated for AI and ADR. Using the provided equations, measured values can be converted to age-appropriate percentile and Z-score. The 2 parameters exhibited strong correlation (Pearson correlation=-0.789, P<0.001). For every unit increase in ADR, AI decreased by 0.94 degrees. CONCLUSIONS: We present updated normative values of AI that expand up to age 14, and novel reference values for ADR. The reference curves allow for the easy conversion of measured values to percentile and Z-score. Using the presented method during surveillance of the pathologic hip, change in acetabular development can now be assessed in a manner that is independent of age and the natural development of the acetabulum. LEVEL OF EVIDENCE: Level IV-case series.