The number of CT scans performed in the pediatric abdomen in the U.S. is high compared with Europe, possibly because doctors fear legal action in the case of a missed pathology or disease. Rather than using CT for appendicitis, many doctors in the Netherlands still prefer to use ultrasound to visualize the swollen, fluid-filled, or normal appendix.In cases where the appendix is not clearly depicted, careful use of ultrasound can still be of great diagnostic value. Between 2000 and 2005, Dr. Herma Holscher from the Juliana Children's Hospital in The Hague noticed that secondary signs appearing on ultrasound as dilated bowel loops or infiltrated fat indicated a high probability of appendicitis. Conversely, their absence suggested a low likelihood of appendicitis. This finding increased ultrasound's sensitivity from 80% to 92%.Most Dutch practitioners now regard ultrasound to be almost as sensitive as CT for appendicitis detection, resulting in 2006 in an official hospital protocol.Ultrasound compares favorably with CT in terms of invasiveness, radiation exposure, and cost. An ultrasound examination in the Netherlands costs around €80, compared with €300 for CT. More CT scans can be performed per hour than ultrasound examinations, but an ultrasound scanner is relatively maintenance-free. CT can also be difficult to interpret in children under the age of five with little abdominal fat, rendering ultrasound the modality of choice, according to Dr. Erik Beek, head of pediatric radiology at Wilhelmina Children's Hospital in Utrecht. He is a strong advocate of ultrasound use in the diagnosis of appendicitis."Appendicitis is often missed in small children, both by clinicians and by imaging specialists, due to atypical symptoms. By the time they receive medical attention, the appendix is quite often already perforated," Beek said.Doctors at Wilhelmina Children's often use laparoscopic procedures in suspected cases of appendicitis in the very young."The process is more expensive than basic ultrasound, but how do you calculate the cost of missed appendicitis, which can quickly move out of control, resulting in abscess and even bowel resection?" he said. "There might be several negative laparoscopy results, but these may well outweigh the cost of one child undergoing bowel surgery."Returning to the question of CT's growing role in medical imaging, Beek opposes a recent protocol proposal from SKION, a Dutch organization for patients with malignant lymphoma. SKION proposes at least 14 CT scans over a period of around five years, the biggest number of these falling within the first few months. The Dutch pediatric group wants to reduce this figure to five or six CT scans. Beek recognizes that faster imaging times for CT will lead to greater use of the modality but warns that radiation exposure remains a crucial consideration."According to the literature, the use of x-rays for medical purposes is now giving more radiation to the population than the natural background of radiation in the environment," Beek said. "Children have their whole lives ahead of them, and given that it could be 20 years before a radiation-induced tumor appears, this may be a problem." Patience with patients is key to effective pediatric imaging, said Dr. Miguel Rasero of the pediatric radiology department at 12 October Maternity and Infant Hospital in Madrid. He cited high-frequency, high-resolution ultrasound, followed by MRI, as the technique of choice for imaging the pediatric biliary tree. "Doctors should perform a ‘dedicated study' to be useful to the clinician and know the prevalent diseases to look for in children. ‘Dedicated' means be patient. Children don't always cooperate. Small structures sometimes aren't visible due to air. A diagnosis takes time and effort," he said.MRI also needs a dedicated examination using small coils and close analysis of the study, due to the wide range of body size and other differences that exist between, for example, a neonate of 4 kg with congenital problems or a 14-year-old transplantee weighing 80 kg."In adults, there are protocols for liver and biliary imaging, and usually the same coils and techniques are used, despite body size. There are very few protocols for imaging children," Rasero said.A pediatric radiologist or a radiologist with pediatric training should perform the examination, he said. A close relationship with the clinician is necessary to provide background on surgery performed and pathology suspected.Biliary disorders are common in liver transplants in children. The procedure is more difficult than in adults because a portion of the liver, rather than a whole one, is transplanted, resulting in potential problems with connections to the biliary tract."Doctors have to resolve such problems without open surgery through invasive techniques, which are particularly useful in transplant problems and the removal of biliary stones," he said.
 |  | |
| Inflamed appendix with diameter of 10 mm contains fluid and is not compressible. (Provided by E. Beek) | Inflamed fat and bowel loops without peristalsis as secondary signs of appendicitis. (Provided by E. Beek) | |
 |  | |
| Sagittal fetal MR scan shows choledochal cyst (arrow). (Provided by M. Rasero) | Nine-month-old girl with biliary atresia. Partial liver transplant (left lobe). MR cholangiogram. Axial view shows intrahepatic bile ducts dilatation due to stenosis at anastomosis (arrows). (Provided by M. Rasero) |
