1) Learn about the various modalities available for the evaluation of diffuse liver disease in children. The emphasis of the talk will be on MRI techniques like Diffusion weighted imaging, MR spectroscopy and MR elastography in diffuse hepatic pathology. The three F's of fat, fibrosis and iron (Fe) will be tackled in terms of diagnosis, and quantification. These will be reviewed via case examples. Also, a thorough review of the existing literature will be presented during the course of the talk.

Diffuse liver pathology in children has traditionally been evaluated using ultrasound (US) and CT scan. US is relatively operator dependent and lacks from an inability to quantify. CT carries the inherent disadvantage of ionizing radiation, which is detrimental for pediatric use, especially since it cannot be used as a follow-up tool. The superior tissue contrast with MRI and benefit of lesion characterization in the setting of diffuse liver disease has made it an attractive first line modality . Apart from diagnosis, the ability to quantify iron, fat and fibrosis has made it extremely useful in clinical practice. MR applications like diffusion weighted imaging, spectroscopy and elastography has generated immense interest in the field of pediatric diffuse liver disease. Recent research and early clinical data holds great promise for the future in this regard.

Measurement of hepatic fat fraction (%) using dual- and triple-echo gradient-recalled-echo sequences is an easy way to evaluate fatty liver even in children. However, the normal range of hepatic fat fraction on these sequences in children is not known yet. The purpose of this study was to evaluate normal range of hepatic fat fraction on these sequences in healthy children.

We retrospectively reviewed children who visited our medical check-up clinic for last two years. Age, sex, height, weight, body mass index, and laboratory findings including liver function tests, cholesterol, and triglyceride level were reviewed. Hepatic fat fraction (%) was measured on the dual- and triple-echo gradient-recalled-echo sequences of our routine check-up MR protocol performed at 3T. We excluded children with abnormal laboratory finding or overweight (body mass index more than 25 kg/m2). Paired t-test was used to compare dual and triple fat fraction. Pearson's chi-squared test was used to evaluate the correlation between fat fraction and clinical or laboratory findings.

Among the total 72 children visited our clinic during the study period, 18 were excluded due to the abnormal laboratory findings or overweight. The enrolled 54 children (M:F = 26:28) were 5-15 years old with a mean of 9 years. Dual fat fraction (range 0.1-8.0%, mean 2.3 ± 2.0 %) was lower than triple fat fraction (range 0.4-6.5%, mean 2.9 ± 1.4 %) (p=0.006). Eight children (8/54, 15%) on dual and six children (6/54, 11%) on triple-echo sequences showed more than 5% fat fraction. In the correlation analysis, only dual fat fraction and triglyceride level was correlated significantly (Pearson's correlation coefficient 0.314, p=0.021).

The upper limit of normal hepatic fat fraction was 8% on dual- and 6.5% on triple-echo sequences. Dual fat fraction was lower than triple fat fraction and correlated with triglyceride level in healthy children.

Knowing normal range of hepatic fat fraction using dual- and triple-echo gradient-recalled-echo sequences of MRI is important for accurate diagnosis of fatty liver in children.

Low signal-to-noise (SNR) could interfere with hepatic fat assessment by magnitude-based MRI (mMRI). The purpose of this study was to assess in children the accuracy of a high-SNR (Hi-SNR) mMRI sequence to determine hepatic proton density fat fraction (PDFF), at PDFF values less than ten percent.

In this prospective, single-site, IRB approved, HIPAA compliant study, a Hi-SNR variant of an mMRI sequence was developed by increasing slice thickness from 8 to 10 mm, and decreasing matrix from 224x128 to 128x92. Pediatric subjects with known or suspected non-alcoholic fatty liver disease (NAFLD) were recruited, provided written informed consent, and underwent 3T MR examinations including mMRI and an advanced multi-TR-TE magnetic resonance spectroscopy (MRS) sequence capable of measuring T1 of water and fat as well as PDFF. The mMRI PDFF values used in this study are the means of three circular 1-cm radius regions of interest (ROIs) placed on source mMRIs co-localized to the MRS voxel location, one slice above that location, and one slice below that location. Linear regression models were used to assess accuracy of MRI-estimated PDFF for the three ROI locations, using multi TR-TE MRS PDFF as reference.

Standard and Hi-SNR mMRI, and multi-TR-TE MRS (to measure PDFF and T1) were obtained for 19 children (13 male, 6 female, age 11.8 ± 2.5 years). Regression analysis of Hi SNR mMRI using multi-TR-TE MRS had a slope, y-intercept and R2 value, respectively, of 0.960, 1.216% and 0.993 for all 19 subjects; and 1.185, 0.602% and 0.822 for the 13 subjects with PDFF less than ten percent. Those values for standard mMRI were 0.987, 0.738% and 0.990 for all 19 subjects; and 1.139, 0.240% and 0.691 for the 13 subjects with PDFF less than ten percent.

In children with known or suspected NAFLD, correlation of Hi-SNR MRI PDFF with MRS was similar, or slightly improved compared to that for mMRI, for PDFF values less than ten percent.

PDFF estimation using a high SNR mMRI variant sequence in children is feasible, and may be helpful if future research suggests that low SNR affects accuracy.

Acoustic radiation force impulse (ARFI) imaging has been developed as a new non-invasive ultrasound-based elastography modality to investigate liver stiffness using shear wave velocity (SWV).
The aim of this study was to evaluate the role of ARFI imaging for assessing episodes of liver dysfunction (rejection, hepatitis, cholangitis and fibrosis) during the post-operative course after pediatric LT.

ARFI was performed using an US device (Acuson S2000, Siemens Medical Solutions) equipped with a 4-MHz transducer. SWV by ARFI imaging was performed in 59 pediatric LT recipients (median 6 month after transplantation). Liver transplantation was performed with a full liver graft in 15 cases (25%) and with a split liver (segments II-III) in 44 (75%). SWV was measured ten times to quantify hepatic stiffness.
Liver biopsy and laboratory analysis (including aminotransferases, alkaline phosphatases, albumin and bilirubin) were performed in a range of time from one day to one month from the ARFI imaging.
SWV was compared to biochemical parameters using liver biopsy as reference standard. Data were evaluated retrospectively.

During the study period ARFI was performed 138 times. According to histopathology there were 15 rejections, 29 hepatitis episodes, 12 cholangitis episodes. Median SWV (m/s, IQR) was higher in patients with diagnosis of graft rejection than in patients without liver disease [2.03, 1.67-2.44, vs 1.22, 1.09-1.31, p < 0.01]. Median SWVs in patients with hepatitis and cholangitis were respectively 1.80, (IQR = 1.49-2.06) and 2.07 (IQR = 1.91-2.48). A few patients had fibrosis with a median SWV of 1.67 m/s. At ROC curve analysis ARFI resulted able to predict rejection (AUC = 0,932), hepatitis (AUC = 0,916) and cholangitis (AUC = 0,949). Statistical analysis wasn't reliable for fibrosis (n = 4).

SWV obtained by ARFI predicts the diagnosis of rejection, hepatitis and cholangitis in pediatric liver transplantation independently to biochemical markers.
ARFI could be useful to reduce the number of liver biopsy in order to guide the immunosuppressive therapy.

ARFI, together with serological markers, is an efficient modality for the diagnosis of graft dysfunction allowing the reduction in the number of liver biopsies in pediatric patients after LT.

To assess liver fibrosis severity with acoustic radiation force impulse (ARFI) quantification in biliary atresia(BA) patients before Kasai surgery.

Patients with conjugated hyperbilirubinemia of unknown causes were prospectively evaluated. BA was diagnosed with laparotomy and cholangiography, liver biopsy was performed in the process of operation. Subjects without hepatobiliary diseases were recruited at the same period as controls. The pSWE with ARFI(Acuson S2000, Virtual Touch Tissue Quantification mode) was performed on all subjects before surgery and ARFI values were calculated in BA patients and control group. The difference between the two groups was statistical analyzed.

There were 27 BA patients and 20 controls in total. The ARFI values in patients were significantly faster than controls(P<0.001). Madian and mean values of ARFI according to liver fibrosis stages in BA patients were 1.16, 1.16m/s(F0), 1.70, 1.69m/s(F1), 1.67, 1.78m/s(F2), 2.21, 2.14m/s(F3) and 2.71, 2.65m/s(F4), respectively. In control group, median and mean values of ARFI were 1.11 and 1.13m/s, respectively. The correlation between ARFI and fibrosis stages was analyzed with spearman correlation coefficient, and r=0.757(P<0.001).

ARFI could reflect the liver fibrosis, and had good correlation with liver fibrosis stages in BA patients. It may become noninvasive method to predict the prognosis and determine the treatment in the future.

ARFI is a reliable noninvasive method in evaluating the severity of liver fibrosis in BA patients before Kasai surgery.

1) To understand the imaging findings on prenatal ultrasound which may alert the radiologist to the possibility of DSD, a proposed imaging evaluation for the post natal evaluation of a newborn with DSD, and the most common types of DSD that we encounter in the newborn child.

http://media.rsna.org/media/abstract/2014/14001055/VSPD32-06 sec.pdf

Inflammatory bowel disease (IBD) is a general term used to describe the idiopathic inflammatory disorders of the gastrointestinal tract. The most common types of IBD are Crohn disease and ulcerative colitis. A number of imaging studies can be used to diagnose IBD in the pediatric population. Over the past ten years, CT and MR enterography have become the imaging tests-of-choice due to their image quality, speed of procedure, lack of bowel preparation, and ability to diagnose the extraintestinal complications of IBD. The purpose of this talk is to compare the advantages and disadvantages of CT and MR enterography, describe the unique components of the imaging protocol required to perform CT or MR enterography in children, and describe the common imaging findings of IBD in the pediatric population.

We evaluated qualitative and quantitative magnetic resonance enterography (MRE) findings which best correlate with mucosal healing assessed by ileocolonoscopy as a reference standard.

In this IRB-approved, HIPAA-compliant retrospective study, patients 18 years of age or below with Crohn's disease were identified who underwent two ileocolonoscopy exams to assess disease activity with an MRE closely timed with the second endoscopy. Two pediatric gastroenterologists reviewed the paired endocopic exams by consensus to assess inflammatory activity as reference. All bowel segments with macroscopic evidence of inflammation on the first endoscopy were included in the study, and were then categorized for the presence or absence of mucosal healing (MH) based on whether macroscopic inflammation was observed on the second endoscopy. An experienced pediatric abdominal radiologist evaluated the corresponding MRE exams of these patients, blinded to the endoscopic results, for multiple imaging features associated with active inflammation. Imaging-endoscopic correlation was then performed.

25 patients were included in the study (mean age 17.6 + 2.8 years) with a mean time between MRE and endoscopy of 12.4 + 7.3 days. On endoscopy, 38 bowel segments demonstrated MH and 22 segments demonstrated persistent inflammation. Among imaging features, MRI Index of Activity (MaRIA) score <8 (accuracy 85%, sensitivity 89%, specificity 77%) and bowel wall thickness (WT) < 4mm (82%, 87%, 73%) were most strongly associated with MH ( P < 0.0001, Fisher's Exact Test). The average WT in healing segments was 2.7 + 0.9 mm compared with 5.2 + 2.2 mm in segments with persistent inflammation (P=<0.0001, Student's t test). Other MRE features significantly (P < 0.005) associated with MH included mesenteric hypervascularity (78%, 97%, 45%), and bowel wall T2 hyperintensity (78%, 92%, 55%).

MRE is an accurate noninvasive technique for assessing mucosal healing in pediatric patients with Crohn's disease. The MRE features most strongly associated with MH include MaRIA score < 8 and WT < 4 mm.

MRE assessment of mucosal healing has great potential in pediatric Crohn's disease as a noninvasive imaging biomarker of disease activity and a therapeutic endpoint of clinical trials.

Prospective evaluation of the performances of DWI for the detection of active lesions on MR-enterography in children with IBD.

Sixty five children (mean age 12.9 years (3-18 years), median age 14 years) with suspected or known IBD were examined by MR-enterography (1.5 Tesla magnets Philips - Eindhoven and GE - Milwaukee). Preparation included pre-examination ingestion of a mixture of Mannitol and water. T2 weighted, T1 after Gadolinium injection and diffusion weighted sequences were obtained. All images were reviewed on a PACS system by two radiologists, each blinded to the clinical data and to the conclusion of the second reviewer. The digestive tract was divided into 7 segments. The 2 radiologists were asked to analyze the images obtained and to report on the presence of active lesions defined as bowel thickening observed on T2 sequences associated with contrast enhancement. The radiologists analyzed successively and independently the images obtained by combining T2 and DWI on one site, T2 and T1 + Gadolinium on the other. The latter was considered as the gold-standard. Whenever no agreement was observed, analysis with consensus was obtained. Inter-observers agreement and sensitivity, specificity, PPV and NPV were calculated.

The couple « T2 + diffusion » detected 64 lesions in 42 patients whereas the couple "T2 + T1 with Gadolinium" detected 58 lesions in 36 patients. The inter-observer agreement was excellent with a Kappa coefficient of 0.84. Sensitivity, specificity, PPV and NPV for the couple "T2+DWI" for the detection of active lesions of IBD were respectively 100 %, 96 %, 79 % and 100 %. The accuracy between the two techniques reached 97%, with Kappa coefficient of 0.86. Seven supplementary lesions were detected by DWI and not by T1+gadolinium. 5/7 had a endoscopic or histologic study confirming active lesions.

Associated with T2 weighted sequence, DWI have equivalent or probably better performances than T1+gadolinium.

Its use would allow to perform shorter examination and obviate the need for gadolinium injection.

To compare DWI, post-gadolinium enhanced MRI (PGE) and bowel wall thickness (BWT) in active PUC with a group of normal controls on endoscopy.

This is a retrospective study that included newly diagnosed patients with PUC who underwent MRE within 7 days after endoscopy and a group of controls with normal endoscopy findings. Bowel was divided in Cecum (Ce); ascending colon (AC); transverse colon (TC), descending colon (DC); sigmoid colon (SC); and rectum (Re). Terminal ileum was not affected. MRE was performed in a 1.5 T Magnet. Protocol included coronal and axial DWI, b=1000; pre- and post- gadolinium coronal dynamic multiphase and axial LAVA fat saturation. DWI was restricted (DR) if there was high signal intensity on b1000 and corresponding low signal intensity on the ADC map. PGE was positive if there was avid mucosal enhancement in comparison with the small bowel. Endoscopy was positive if ulceration, inflammation or edema were documented. Two readers were blinded to diagnosis and assessed BWT, DR and PGE in each segment. Interclass correlation (ICC) and Linear Mixed Effects Models with Random Intercept (LMEMRI) were calculated for BWT. Inter-rater reliability (kappa), sensitivity (Se) and specificity (Sp) for DWI and PGE were calculated.

Data from 15 patients with PUC and 15 normal controls was analyzed. Kappa values for DWI/PGE were: Ce 0.64/0.76, AC 0.62/0.67, TC 0.71/0.64, DC 0.81/0.49, SC 0.87/0.78 and Re 0.86/0.55. ICC for BWT were Ce 0.22, AC 0.63, TC 0.65; DC 0.40, SC 0.41 and Re 0.59. For reader 1/reader 2: Se of DWI: Ce 91/73%; AC 69/62%; TC 77/69%; DC 100/93%; SC and Re100%. Sp of DWI: Ce 94%; AC 100%; TC 94/100%; DC 87/100%; SC 93%; and Re 87%. Se of PGE: Ce 36/55%; AC 31/46%; TC 38/62%; DC and SC 60/73%; and Re 47/67%. Sp of PGE: Ce and AC 100%; TC 94/100%; DC and SC 93/100%; and Re 87/93%. LMEMRI for BWT showed statistical difference in all segments (p<0.01) with exception of AC (p=0.11). The median difference was 0.5-1.5mm

PGE and DWI show high inter-rater reliability. Se of DWI detecting active PUC is superior to PGE; whereas specificity is comparable. BWT showed significant difference between active PUC versus controls, but these differences were only 0.5- 1.5 mm

Routine MRE should include DWI sequences which increase the degree of detection of active PUC within 7 days of diagnostic endoscopy with high sp values when compared with controls

To facilitate consistent, reliable communication among providers, we developed a novel scoring system for reporting limited right lower quadrant ultrasound (US) exams obtained for suspected pediatric appendicitis. The purpose of this study was to evaluate implementation of this scoring system and its ability to risk-stratify children with suspected appendicitis.

We developed a risk-stratification scale (Appy-Score) and structured reporting template for limited abdominal US exams obtained for suspected pediatric appendicitis. Appy-Score strata were: 1=normal completely visualized appendix; 2=normal partially visualized appendix; 3=non-visualized appendix, 4=equivocal; 5a=non-perforated appendicitis; 5b=perforated appendicitis. The Appy-Score was applied retrospectively to all limited right lower quadrant US exams ordered through our Emergency Department during a 5-month pre-implementation period (1/1/2013-5/31/2013), and Appy-Score use was tracked prospectively post-implementation (7/1/2013-9/30/2013). Diagnostic performance measures of US exams were computed post-implementation. Secondary outcomes included CT imaging following US exams and negative appendectomy rates.

We identified 1,235 patients in the pre- and 687 patients in the post-implementation groups. Appy-Score use increased from 24% in July to 89% in September (p=0.0001). The likelihood of appendicitis progressively increased with each score stratum. Sensitivity, specificity, positive predictive value and negative predictive value post-implementation were 93.8%, 92%, 83.8%, and 97.1%, respectively. The rate of CT imaging after US decreased from 8.6% pre-implementation to 5.9% post-implementation (p=0.048). Negative appendectomy rates did not significantly change (4.4% vs. 4.1%, p=0.88).

The use of a risk-stratified scoring system and standardized template for reporting the results of US exams for suspected pediatric appendicitis clearly communicated the likelihood of appendicitis to the treating physician and decreased the need for CT imaging. Future studies should assess whether this streamlines care in the emergency room setting and whether the risk strata are generalizable to other institutions with varying expertise in US imaging.

A scoring system for reporting limited US exams performed for suspected pediatric appendicitis can risk-stratify patients and decrease the rate of follow-up CT imaging.

Describe the normal anatomy and characteristics of the anus, rectum, levator ani, puborectalis, ischiorectal fossa, sacrum and coccyx using a novel, posterior, trans-sacrococcygeal, high resolution ultrasound imaging approach. Illustrate how to perform the technique and validate the information obtained by comparison with anatomic drawings and selected CT and MR images, which are more commonly used to evaluate this area.

Retrospective review of images obtained as part of routine spinal ultrasound evaluations in newborns between 2005 and 2014. High resolution linear ultrasound probes were used via a trans-sacrococcygeal approach, in the posterior sagittal and axial planes with the infant prone. A series of images demonstrate rectum, anus, presacral space, levator ani, puborectalis, sacrum, coccyx and ischiorectal fossa. Review of CT and MR imaging data, obtained for unrelated reasons, has been used to corroborate, compare and contrast with the ultrasound imaging data.

The anal canal is particularly well seen by high frequency, linear, ultrasound probes, when evaluated from a posterior trans-sacrococcygeal approach in newborns. It has a characteristic cyclindrical appearance quite distinct from the rectum. The length, muscle thickness, anorectal ring, anal verge, and anorectal angle, are nicely depicted on sagittal images. The mucosa, internal and external anal sphincteric layers, and anorectal course through the levator ani muscles are well seen on axial images. The anal canal orientation with respect to rectum, sacrum, vagina and urethra can also be defined on the sagittal images. The integrity of the posterior sacrococcygeal elements is clearly seen.The images compare favorably with MR and CT of the same area without need for sedation or ionizing radiation in this young population.

Posterior, midline, trans-sacrococcygeal, high resolution, ultrasound imaging is a reproducible technique, which demonstrates normal anorectal and pelvic floor anatomy exquisitely well. Facilty with this technique provides useful supplementary data to that obtained by transabdominal and transperineal ultrasound techniques.

Confident demonstration and knowledge of normal ultrasound anorectal complex anatomy from a posterior approach provides a foundation to evaluate anorectal malformations, anterior ectopic anus and cloaca.

1) To discuss key protocol aspects for MR urography in children to reproducibly generate high quality studies and show how MR urography is has widespread application in the evaluation of children with urinary tract disease.