Fred E. Avni

Prospective evaluation of free-breathing diffusion- weighted imaging for the detection of inflammatory bowel disease with MR enterography in childhood population

OBJECTIVE To evaluate prospectively the performance of diffusion-weighted imaging (DWI) for the detection of active lesions on MR enterography (MRE) in children with inflammatory bowel disease (IBD). METHODS MRE of 48 children (mean age 13 years) with suspected or known IBD were blindly analysed by 2 independent readers for the presence of active lesions. Two sets of imaging including DWI and gadolinium-enhanced imaging (GEI) were reviewed. A reader consensus was obtained. The gold standard was histopathological findings. In patient-level analysis and segment-level analysis, sensitivity and specificity were calculated for DWI and GEI and compared using McNemars test or logistic random-effects models. RESULTS At least 1 active lesion was confirmed in 42 (87.5%) children. Sensitivity and specificity for the detection of at least one lesion were 88.1% (95% CI, 74.3-96.1) and 83.3% (95% CI, 35.9-99.6), respectively, for DWI and 66.7% (95% CI, 50.4-80.4) and 83.3% (95% CI, 35.9-99.6), respectively, for GEI. In segment-level analysis, sensitivity and specificity for the detection of specific segment lesions were 62.5% (95% CI, 48.1-75) and 97.1% (95% CI, 93.5-98.7), respectively, for DWI and 45.7% (95% CI, 30.8-61.3) and 98.2% (95% CI, 95.3-99.4), respectively, for GEI. The sensitivity of DWI was significantly better than that of GEI per patient (p = 0.004) and per segment (p = 0.028). CONCLUSION DWI demonstrates better performance than GEI for the detection of active lesions in children with IBD. ADVANCES IN KNOWLEDGE Examination with no intravenous injection-DWI can replace T1 weighted images when paediatric patients are screened with MRE for IBD. Examination performed in free breathing is better tolerated by children.

At the Boundaries of the Abdominal Cavity

When a child presents with acute or subacute abdominal symptoms a series of differential diagnoses are considered and have been developed in the various chapters of our book.

Acute) Renal Failure in the Full Term Neonate

The precise incidence and prevalence of acute renal failure (ARF) in the newborn is uncertain. Studies in NICU (neonatal intensive care units) have shown that this incidence ranges from 6-24% of newborns. Neonates who have undergone cardiac surgery, prematures (see also chapter 4), newborns with sepsis and newborns with severe asphyxia are particularly vulnerable. Nephrotoxic medications may increase the renal damage. Other studies have shown that some newborns have genetic risk factors for ARF (in relation with alteration of the renin-angiotensin-system). Furthermore, ARF may have a prenatal origin associated with IUGR, congenital diseases such as renal dysplasia and CAKUT (congenital anomalies of the kidney and urinary tract), renal cystic diseases or diseases secondary to maternal intake of some medications. Ultrasound (US) is the main imaging technique able to be provide some useful information able to precise the diagnosis.

Abdominal Complications in the Premature Infant

Morbidity and mortality in the premature infant during the neonatal period is related to brain injury, to the consequences of respiratory distress and to acute abdominal complications. The latter includes necrotizing enterocolitis (NEC), hepatobiliary consequences mainly related to the parenteral nutrition, meconium- ileus – like obstruction and vascular damage especially to the kidneys. Iatrogenic diseases usually related to therapeutic measures have also to be considered. Furthermore, short and long term consequences of prematurity related diseases should be taken into account when considering acute abdominal symptoms in older prematures.

Upper Urinary Tract Dilatation in Newborns and Infants and the Postnatal Work-Up of Congenital Uro-nephropathies

In many European countries, obstetric ultrasound (US) is performed routinely during normal pregnancies. This leads to the discovery of many fetal anomalies, and, among them, uro-nephropathies represent one of the largest groups amenable to neonatal management. They are now included in the so-called CAKUT [congenital anomalies of the kidney and urinary tract] group (Renkema et al. 2011; Wiesel et al 2005; Ek et al. 2007).

Imaging and Emergency: What Modalities? What Strategies?

In children, acute abdominal complaints are common presentation in the emergency department. The etiologies, presentations, diagnosis and management vary widely and establishing (rapidly) the diagnosis is often challenging. Imaging techniques are increasingly important to sort out between all possible diagnoses in order to differentiate cases necessitating acute management from those where the management can be organized more “quietly”. A close collaboration with our pediatric colleagues is indispensable in order to define the panel of differential diagnosis to be considered and the degree of emergency before applying imaging. Familial history, history of the disease, clinical and biological data are all of upmost importance.

Acute Renal Failure in Children

In case of acute renal failure (ARF), the primary role of imaging is to exclude post-renal obstructive causes by demonstrating bilateral urinary tract dilatation (unilateral in case of a single kidney). The examination will aim to demonstrate the degree and level of obstruction. Whenever a mass (or a mass effect) is demonstrated, complementary evaluation through MR imaging (preferably) or CT may be necessary in order to precise the diagnosis. The use of contrast material should be carefully evaluated in children with ARF in order to avoid worsen the renal impairment.

Acute Presentation of Anomalies of the Digestive Tract During the Neonatal Period

During the neonatal period, obstruction of the digestive tract often represents a surgical emergency and therefore, a rapid and accurate diagnosis is mandatory. In the era of obstetrical US and antenatal diagnosis, some pathologies will be detected in utero and managed immediately after birth (see also Chapter 5). Yet, the rate of antenatal diagnosis of digestive tract anomalies is still low (30-50%) and many diagnosis will be achieved after birth only mainly on the basis of acute abdominal symptoms. Furthermore, several among the malformations – e.g. Hirschprung disease – are only exceptionally suspected in utero and most cases will be discovered after birth. Some others will present symptoms only after birth (e.g. small left colon).

Congenital Anomalies of the Renal Pelvis and Ureter

Congenital anomalies may involve any level of the collecting system; the most usual presentation is urinary tract dilatation that may already be detected during fetal life. The role of imaging is to determine the origin of the dilatation, i.e., obstructive versus nonobstructive (Table 1 lists the causes of urinary tract dilatation). Other useful information includes the level of the impairment to drainage (so-called obstruction) and its impact on renal function. All these data are important in order to determine the best therapeutic approach.

Acute (Abdominal) Presentations of Non-malignant Hemopathies

Acute (abdominal) presentations of non-malignant hemopathies are often managed by the clinician (vaso-occlusive crisis in sickle cell disease, complications of analgesic medicine (bladder retention or fecaloma). In some specific cases (biliary complications, splenic complications), imaging will be helpful. US is usually the first and often only imaging procedure performed. CT or MR imaging may be performed in cases where there is clinical doubt or when US is inconclusive. The management of borderline hemopathies such as Langerhans cell histiocytosis depends upon their complications and imaging is adapted to their clinical presentation.