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In recent decades, image-guided interventions have become daily routine in radiology departments worldwide. Radiologists and clinicians alike clearly see the advantages of image-guided interventions, as it is minimally invasive, well tolerated by patients and has shown to have a low level of complications. [ABSTRACT FROM AUTHOR]

Appendicitis most commonly occurs over the age of 5 years, is rare in those under 2 years, but may occur at any age and is the most common condition requiring emergency abdominal surgery in children (Janik and Firor 1979). Incidence in the paediatric age group shows wide geographical variation but overall incidence appears to be declining. Previous quoted incidence rates were approximately 1 in every 250 children but a recent study now suggests rates may be as low as 1 in 850 in children and young adults (Williams et al. 1998). The aetiology is that of appendiceal luminal obstruction, most commonly by lymphoid hyperplasia (60%) but also by hard concretions (faecoliths 33%), faecal impaction or appendiceal calculi (appendicolith). Rarer causes in children include tumour, stricture, parasites and Crohn's disease. Appendiceal obstruction is followed by luminal distention, ischaemia and bacterial invasion. Necrosis of the appendiceal wall then develops resulting in perforation and abscess formation. [ABSTRACT FROM AUTHOR]

The radiological approach to the pediatric upper and lower gastrointestinal (GI) tract varies according to the clinical condition of the child, the patient's age and the differential diagnostic considerations. [ABSTRACT FROM AUTHOR]

At birth a normal liver can extend below the costal margin, and occupy two fifths of the abdominal cavity. However, when the child starts growing, these proportions will change to adult proportions. Of the modalities useful in imaging of the liver in children, ultrasound (US) in particular has proved to be an excellent screening and diagnostic tool in children (Siegel 2001a). Conventional radiology can only indirectly "image" the liver, CT "costs" ionizing radiation, while MR is cumbersome and only useful in targeted instances [magnetic resonance cholangiopancreaticography (MRCP), etc.]. [ABSTRACT FROM AUTHOR]

In the normal embryo, the abdominal portion of the foregut is visibly divided into the esophagus, stomach and proximal duodenum by the fifth week (Larsen 2001). During the fifth week, the stomach starts out as a straight tube but since there is differential growth of its dorsal and ventral wall, the greater curvature will become more elongated than the lesser curvature. Continued differential expansion of the superior part of the greater curvature gives rise to the fundus and cardiac incisure by the end of the seventh week. [ABSTRACT FROM AUTHOR]

The esophagus and trachea form from a single common tubular structure that separates into an anterior laryngotracheal groove and a posterior esophagus (Collins 1995). Development of the esophagus begins in the fourth week of fetal life when the respiratory diverticula, or lung buds, appear on the ventral wall of the foregut at the border with the pharyngeal gut. Lateral invagination of the mesodermal esophagotracheal septum gradually partitions this diverticulum from the foregut, thus dividing into the ventral respiratory primordium and the dorsal esophagus. Epithelial growth obliterates the lumen, which recanalizes at the tenth week (Sadler 2000). The esophagus is initially short, but lengthens rapidly with descent of the heart and lungs, and attains normal length by 7 weeks. Occasionally, the esophagus fails to lengthen sufficiently, and the stomach is pulled up into the esophageal hiatus through the diaphragm, resulting in a congenital hiatal hernia (Sadler 2000). [ABSTRACT FROM AUTHOR]

Intestinal obstruction is the most common abdominal emergency in the neonatal period. It is almost always the result of a congenital anomaly of the gastrointestinal tract, which must be rectifi ed surgically if the infant is to survive. Mortality in surgically untreated patients is close to 100%, and the rate of survival is closely related to the time of surgical intervention (Hajivassiliou 2003). The most common clinical findings are abdominal distension, vomiting, and sometimes failure to pass meconium, depending on the level of the obstruction. These findings usually prompt the clinician to consult the radiologist, who must answer three major questions: Is the obstruction present? What is the location of the obstruction? What is the aetiology? The most valuable means of determining whether or not obstruction is present is the plain abdominal radiograph. Plain radiographs are often diagnostic. When not diagnostic, they may provide important clues suggesting the subsequent most valuable diagnostic procedure (Singleton et al. 1977). [ABSTRACT FROM AUTHOR]

A cycle of a graph G is a set C ⊑ E(G) so that every vertex of the graph (V (G), C) has even degree. If G,H are graphs, we define a map φ: E(G) → E(H) to be cycle-continuous if the pre-image of every cycle of H is a cycle of G. A fascinating conjecture of Jaeger asserts that every bridgeless graph has a cycle-continuous mapping to the Petersen graph. Jaeger showed that if this conjecture is true, then so is the 5-cycle-double-cover conjecture and the Fulkerson conjecture. Cycle continuous maps give rise to a natural quasi-order ≻ on the class of finite graphs. Namely, G ≻ H if there exists a cycle-continuous mapping from G to H. The goal of this paper is to establish some basic structural properties of this (and other related) quasi-orders. For instance, we show that ≻ has antichains of arbitrarily large finite size. It appears to be an interesting question to determine if ≻ has an infinite antichain. [ABSTRACT FROM AUTHOR]