Inflammatory Bowel Disease (IBD) includes Crohn disease,
ulcerative colitis and unclassified IBD.
Incidence of IBD is increasing worldwide with wide geographic variability.
A systematic review demonstrates an incidence of 12.7 per 100000 person-years in Europe,
5.0 per 100000 person-years in Asia and the Middle East,
20.2 per 100000 person-years in North America.
Pediatric CD occurs in up to 25% of patients,
often of greater severity than adult IBD.
5% of all IBD patients are children younger than 10 years old and less than 1% is younger than 2 years old.
Very early onset IBD (VEO IBD) is defined as a category that develops in the first 6 years of life and shows different clinical history and bowel involvement.
CD is almost three times more frequent than UC,
while unclassified IBD is less 10%.
CD is an idiopathic chronic inflammatory bowel disease characterized by transmural granulomatous inflammation of the gastrointestinal tract,
that may involve the entire tract,
from mouth to the anus.
Although the exact aetiology is unknown,
it seems that the origin depends on complex interactions between environmental,
genetic and immune factors with activation of mucosal immune responses,
which in turn lead to inflammatory response.
A strong association is reported between Crohn disease and polymorphism NOD 2 that would entail a defect in the innate immune system of mucosal bowel.
In pediatric IBD’s pathogenesis environmental factors (cigarette smoking,
use of FANS,
etc) have less importance due to little time exposure.
Clinical presentation of CD is very variable,
it depends on phenotypes of the disease.
Paris Classification is a new classification system of phenotypes adapted from the adult Montreal Classification about the pediatric IBD age at diagnosis,
disease location and extent,
behaviour and disease severity (impairment growth).
In pediatric CD pan-enteric disease is more typical at onset,
mainly in VEO IBD.
Unlike adult Crohn,
in patients younger than 10 years old colic and upper gastrointestinal tract involvement is present in about 80% of cases and decreases with age while ileum involvement is rare.
Clinical presentations are similar in adults: diarrhea,
weight loss and anemia,
but pediatric patient can show growth retardation,
reduced bone mineral density and malnutrition.
For diagnosis of IBD,
imaging has a critical role in addiction to the clinical history,
physical and laboratory test,
histology obtained with esophagastroduodenoscopy and ileo colonoscopy.
It is performed in all suspected cases of Crohn disease.
CT enterography and MR enterography are cross-sectional imaging techniques optimized for small bowel imaging.
Both can be used to contribute to the initial diagnosis of IBD,
including assessment of inflammatory activity and extent,
to evaluate response to therapy in follow up and identify complications as stricture or penetrating disease (fistula or abscess).
CT has higher spatial resolution so it permits an improvement in detection of small subtle abnormalities.
CT enterography is widely available and it allows to obtain images of the entire abdomen and pelvis in one breath hold,
with less motion artifacts.
The major disadvantage is ionizing radiation exposure.
MRE does not use ionizing radiation.
It has a superior soft tissue contrast that permits more conspicuity of some abnormalities and enhancing areas; the presence of multiple different pulse demonstrate physiologic peristalsis and it shows better bowel alteration when intravenous contrast medium cannot be administrated.
The disadvantage of MRI is long time examinations with multiple breath hold periods with high risk of motion artifacts.
Claustrophobic patients do not tolerate the examination.
Furthermore it is not to be performed in patients with certain implantable devices.
the presence of air in the bowel causes artifacts of magnetic susceptibility with consequent reduction in sensitivity.
The two techniques have same sensitivity (CTE 83%,
MRI 86%) and specifity (CTE 88%,
but because of radiation exposure,
MRI is preferred in young patients as first exam on Crohn disease.
We present pediatric MRE protocols for CD evaluation,
also through a review of the literature.