Renaud Menten

Pediatric diffusion tensor imaging: Normal database and observation of the white matter maturation in early childhood

Recent advances in diffusion tensor imaging (DTI) have made it possible to reveal white matter anatomy and to detect neurological abnormalities in children. However, the clinical use of this technique is hampered by the lack of a normal standard of reference. The goal of this study was to initiate the establishment of a database of DTI images in children, which can be used as a normal standard of reference for diagnosis of pediatric neurological abnormalities. Seven pediatric volunteers and 23 pediatric patients (age range: 0-54 months) referred for clinical MR examinations, but whose brains were shown to be normal, underwent anatomical and DTI acquisitions on a 1.5 T MR scanner. The white matter maturation, as observed on DTI color maps, was described and illustrated. Changes in diffusion fractional anisotropy (FA), average apparent diffusion constant (ADC(ave)), and T2-weighted (T2W) signal intensity were quantified in 12 locations to characterize the anatomical variability of the maturation process. Almost all prominent white matter tracts could be identified from birth, although their anisotropy was often low. The evolution of FA, shape, and size of the white matter tracts comprised generally three phases: rapid changes during the first 12 months; slow modifications during the second year; and relative stability after 24 months. The time courses of FA, ADC(ave), and T2W signal intensity confirmed our visual observations that maturation of the white matter and the normality of its architecture can be assessed with DTI in young children. The database is available online and is expected to foster the use of this promising technique in the diagnosis of pediatric pathologies.

Impact of pre-transplant liver hemodynamics and portal reconstruction techniques on post-transplant portal vein complications in pediatric liver transplantation : a retrospective analysis in 197 recipients

Background and Objective:Portal vein (PV) complications are the most frequent vascular complications in pediatric liver transplant (LT). We hypothesized that pre-LT liver hemodynamic parameters and PV reconstruction technique could predict the risk of PV complications post-LT. Methods:Three hundred seventy-three children had a primary LT. A detailed ultrasound study of the pre-LT native liver hemodynamics was available in 198 cases, with details of PV anastomosis available for 197 of these: end-to-end anastomosis (n = 146, 74%), interposition vein graft technique (n = 28, 14%), or portoplasty (latero-lateral anastomosis of vein graft and recipient PV) (n = 23, 12%). Results:Overall 5-year patient survival rate was 90%. Among the 198 patients with pre-LT hemodynamic data, 79 (40%) had PV hypoplasia (diameter ⩽4 mm), 64 (32%) had a pathological portal flow (nonhepatopetal flow), and 47 (24%) had an arterial resistance index (ARI) ≥1. Abnormal hemodynamics were mostly observed in biliary atresia (BA). Among these 3 parameters, only ARI ≥1 was significantly correlated with a higher rate of PV complications post-LT (P = 0.041). PV complication-free survival at 5 years were 91% for end-to-end anastomosis, 91% for portoplasty, and 62% for interposition vein graft technique (P = 0.002). At multivariate analysis, the use of an interposition vein graft was the only factor to be significantly associated with a higher rate of PV complications post-LT (P = 0.003). Conclusions:PV hypoplasia with liver hemodynamic disturbances was mainly observed in BA. Hepatic ARI ≥1 might be a good predictor of PV complications post-LT. Latero-lateral portoplasty seemed to provide the best results when end-to-end anastomosis is not feasible.

Living Donor Liver Transplantation in Children: Surgical and Immunological Results in 250 Recipients at Université Catholique de Louvain.

Objectives: To evaluate the outcome of pediatric living donor liver transplantation (LDLT) regarding portal vein (PV) reconstruction, ABO compatibility, and impact of maternal donation on graft acceptance. Background: LDLT and ABO-mismatched transplantation constitute feasible options to alleviate organ shortage in children. Vascular complications of portal hypoplasia in biliary atresia (BA) and acute rejection (AR) are still major concerns in this field. Methods: Data from 250 pediatric LDLT recipients, performed at Cliniques Universitaires Saint-Luc between July 1993 and June 2012, were collected retrospectively. Results were analyzed according to ABO matching and PV complications. Uni- and multivariate analyses were performed to study the impact of immunosuppression, sex matching, and maternal donation on AR rate. Results: Overall, the 10-year patient survival rate was 93.2%. Neither patient or graft loss nor vascular rejection, nor hemolysis, was encountered in the ABO nonidentical patients (n = 58), provided pretransplant levels of relevant isoagglutinins were below 1/16. In BA recipients, the rate of PV complications was lower after portoplasty (4.6%) than after truncal PV anastomosis (9.8%) and to jump graft interposition (26.9%; P = 0.027). In parental donation, maternal grafts were associated with higher 1-year AR-free survival (55.2%) than paternal grafts (39.8%; P = 0.041), but only in BA patients. Conclusions: LDLT, including ABO-mismatched transplantation, constitutes a safe and efficient therapy for liver failure in children. In BA patients with PV hypoplasia, portoplasty seems to constitute the best technique for PV reconstruction. Maternal donation might be a protective factor for AR.

Performance of chest ultrasound in pediatric pneumonia

OBJECTIVE The objective of this study was to evaluate the performance of ultrasound in detecting lung consolidation in children suspected of pneumonia, in comparison to the current gold standard, chest X-rays. MATERIALS AND METHODS From September 2013 to June 2014, a monocentric prospective study was performed on all children between 0 and 16 years-old, referred for chest X-ray for suspected pneumonia. Each child was examined by chest ultrasound by an examiner blinded to the chest X-ray. The presence or absence of areas of consolidation, their number and location were noted for each technique. The size of the consolidations identified only on ultrasound was compared with that of consolidations visible on both techniques. RESULTS 143 children (mean age 3 years; limits between 8days and 14 years) were included. Ultrasound detected at least one area of consolidation in 44 out of 45 patients with positive X-rays. Of the 59 areas of consolidation on X-ray, ultrasound identified 54. In the 8 patients with negative X-ray, ultrasound revealed 17 areas of consolidation. The mean size of consolidations visible only on ultrasound was 9.4mm; for consolidations visible on both techniques the mean size was 26mm (p<0.0001). The sensitivity and specificity of ultrasound were calculated at 98% and 92%. PPV and NPV were 85% and 99%, respectively. CONCLUSION Chest ultrasound is a fast, non-ionizing and feasible technique. With its high negative predictive value, it can replace X-rays in order to exclude lung consolidation in children, thus reducing radiation exposure in this population.

Measurement of bone cyst fluid volume using k-means clustering

We designed a semiautomatic segmentation method to easily measure the volume of a bone cyst (simple or aneurysmal) from magnetic resonance imaging (MRI). This method only considers the fluid part of the cyst, even when there are several fluid intensities (fluid-fluid levels) or the cyst is multi-loculated. The nonhomogeneity phenomenon inherent in MRI was handled by a k-means clustering algorithm that classified all of the voxels corresponding to the cyst fluid as the same voxel intensity. Level-set segmentation was expanded into the whole cyst volume and the resulting segmented volume provided the measured cyst volume. The semiautomatic method was compared with the usual manual method (manual contour tracing) in terms of its ability to measure a known volume of water (gold standard) as well as the volume of 29 bone cysts. Both methods were equivalent with regards to the gold standard, but the semiautomatic method was more accurate. In terms of the experimental measurements, the semiautomatic method was more repeatable and reproducible, and less time-consuming and fastidious than the manual method. Our semiautomatic method uses only freeware and can be used routinely whenever measurement of a bone cyst volume is needed.

Development of renal and iliac aneurysms in a child with generalized infantile myofibromatosis

Infantile myofibromatosis is a rare disorder characterized by the formation of tumors in the skin, soft tissues, bone, and viscera. We report the case of a 3-week-old girl who presented with severe hypertension due to generalized infantile myofibromatosis including renal involvement. The infant was treated by chemotherapy and showed progressive regression of the tumors. However, her evolution was marked by the development of aneurismal dilations of the renal and iliac arteries as observed in fibromuscular dysplasia. We discuss the possibility of a link between these two mesenchymal disorders.

Planispheric multiplanar reformatted CT: a new method for evaluation of paediatric congenital spine abnormalities.

We describe an original reconstruction method for spine CT performed in four patients with single or multiple congenital spine abnormalities. Conventional radiographic imaging is at the forefront of diagnosis and follow-up of congenital scoliosis, but is frequently difficult to interpret. Three-dimensional CT reconstruction facilitates visualization of complex anatomic structures, but does not give a reliable assessment of failures of segmentation. Mental three-dimensional reconstruction of the information displayed by classical multiplanar reformatted CT remains difficult. Planispheric reformatted imaging allows the visualization of all deformities in a single plane.

Postendoscopic duodenal hematoma in children: Ultrasound diagnosis and follow‐up

Intramural duodenal hematomas have most frequently been reported in children in a traumatic setting. We present two cases of duodenal hematoma that occurred after upper gastrointestinal tract endoscopy with biopsy in children without significant prior medical history. The diagnosis was made by ultrasound, in correlation with the clinical presentation. Because the patients were hemodynamically stable, they were treated conservatively and the regression of the hematoma was followed up with ultrasound until its complete resolution. These cases demonstrate the risks of endoscopy, which are not to be neglected even in children without impaired coagulation, and the manner in which ultrasound can provide the correct diagnosis and follow‐up.

Reply to Dr. B. Karmazyn regarding ‘Duodenum between the aorta and the SMA does not exclude malrotation’

Sir, In response to Dr. Karmazyn’s letter [1], we would like to clarify the following: We disagree with the statement that the study evaluated patients with suspected malrotation, since this was not the case. The population, as stated in the materials and methods segment of the text, included asymptomatic patients explored for recurring respiratory symptoms [2]. Moreover, in all cases, US demonstrated the absence of whirlpool and the parallel position of the mesenteric vessels, excluding (unexpected) midgut volvulus. We agree with the title of Dr. Karmazyn’s letter, given that “the presence of the duodenum between the SMA and the aorta does not exclude malrotation,” complicated by midgut volvulus. If the duodenum twists around the axis of the mesenteric vessels, as it does in midgut volvulus, this clockwise rotation can position a portion of it behind the mesenteric vessels, as shown in Figs. 3 and 4 in his letter [1]. However, in these cases, the authors did not show parallel orientation of the superior mesenteric vessels. The embryology of intestinal rotation demonstrates the importance of the relationship between the duodenum and the mesenteric vessels. Upper gastrointestinal fluoroscopy defines the normal duodenal position in relation to bone structures. The advantage of US therefore resides in its ability to visualize the direct relationship between the mesenteric vessels and the duodenum and to identify those situations in particular in which the duodenum is not located in the aorto-mesenteric angle. In conclusion, retromesenteric D3 excludes uncomplicated malrotation, and parallel orientation of the mesenteric vessels excludes midgut volvulus. Only cross-sectional imaging as a whole and US in particular can achieve both objectives in the same setting and in the same study, not UGI.

Imaging of primary unilateral pulmonary hypoplasia: a case report

BackgroundPulmonary hypoplasia is a rare cause of neonatal dyspnea almost always secondary to other conditions. We report an exceedingly rare case of primary unilateral pulmonary hypoplasia.Results and discussionThis case illustrates the role of prenatal magnetic resonance imaging when this condition is suspected during the fetal life. Combined with ultrasounds, this imaging modality offers a three-dimensional evaluation of the lungs that can be critical for postnatal medical management.