Emergency Paediatric Radiology
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Purpose: To evaluate the impact of a paediatric radiological protection campaign, implemented in the emergency units of a healthcare provider network in Brazil. This campaign aimed to promote awareness among emergency department physicians, regarding justification of paediatric X-ray referrals for paranasal sinus, chest and CT exams, as a strategy to reduce exposure to ionising radiation.
Method: Frequency analysis of common paediatric imaging referrals from 19 emergency departments was performed for a 3-year period (2015-2018) to coincide with before, during and after the implementation of the radiation protection campaign. The campaign was multifaceted and involved dissemination of educational materials and imaging referral guidelines along with quarterly meetings with participating centres' leaderships. Additionally, patient dose cards were distributed to patients/carers. The Chi-Square test was used to examine the association between the type of examination and the patient's age group. Exact-Fisher test was performed to check for an association between participant engagement and the existence of the radiation protection committee.
MR imaging, whilst excellent for characterising and staging a primary malignancy, has less of a role in the emergency scenario apart from in neurological emergencies, such as suspected spinal cord compression.
This pictorial review serves to illustrate the many facets and scenarios seen during emergency presentations of paediatric cancers. We outline the abnormalities and best imaging modalities for each scenario by body systems and include cases seen at presenting diagnosis, prior to curative surgical resection and unrelated to chemotoxic agents. Acute presentations relating to complications of treatment and infective diseases are not included, given their substantial coverage elsewhere in the literature [7,8,9,10].
Tumours of the central nervous system are the leading cause of cancer-related deaths in children [11], with the majority located in the infratentorium [12]. Both low- and high-grade tumours may cause acute hydrocephalus either from extrinsic compression or intraventricular extension of the tumour adjacent to the foramen of Monroe, cerebral aqueduct, fourth ventricle and outlet foramina [13]. The commonest low-grade tumour in the posterior fossa includes pilocytic astrocytomas whilst high-grade tumours are divided into ependymomas and embryonal tumours (such as medulloblastomas, atypical terato-rabdoid tumours (ATRT) and embryonal tumours with multi-layered rosettes (ETMR)) [12]. (Fig. 1a, b) In the emergency setting however, determining the tumour subtype is not the main goal, which should be directed towards identification and localisation of the mass, any adverse complications (e.g. hydrocephalus or haemorrhage) and aiding the neurologists and neurosurgeons in planning subsequent clinical interventions. This may include the insertion of an extraventricular drain (EVD) in the first instance, to help relieve the hydrocephalus, occasionally to drain haemorrhage and provide ongoing intracranial pressure (ICP) monitoring [14]. One large case series of approximately 180 children found that an underlying cerebral neoplasm was the primary indication for an EVD in almost a third (32.2%) of cases, with astrocytomas accounting for 43.1% of all responsible tumours [13].
Causes of pericardial effusion in paediatric oncology patients are myriad ranging from general medical causes of cardiac failure, side effects of chemotherapy, radiotherapy or haematopoietic stem-cell transplantation [47] to malignant pericardial effusions. The latter is a rare complication associated with pericardial infiltration from leukaemia and lymphoma [48, 49], intrapericardial [50] or primary cardiac tumours [51] (Fig. 10). Urgent cardiology consultation with echocardiography and a view to proceeding to pericardiocentesis is essential.
The diagnosis is clinical; however, by identifying venous compression, particularly IVC obstruction on either an abdominal ultrasound or portal venous phase, post-contrast CT study, the radiologist can help raise awareness [54]. Surgical referral is essential and emergency decompressive laparotomy may be required. Possible aetiologies include any cause of a rapid increase in abdominal contents such as large (bilateral) Wilms tumours [55], rapidly proliferating acute lymphoblastic leukaemic infiltrates [56], giant ovarian masses [57] (Fig. 12) and ascites [58].
Whilst a pre-contrast CT of the affected body part may be routinely acquired in adult radiology, this is generally avoided in paediatric imaging with only the arterial and portal venous phase imaging being sufficient [76].
End-organ damage or haemorrhagic stroke secondary to refractory hypertension may be the presenting feature of some paediatric malignancies. These can be biochemical in nature (such as from excessive catecholamine production in neuroblastomas or phaeochromocytomas) or from mass effect on the aorta or renal arteries (Fig. 21).
When cross-sectional imaging is needed in the emergency, clinically acute setting in our institution, we tend to use CT before MRI in smaller children in spite of the exposure to radiation. MDCT has a spatial resolution superior to MRI, and there is generally no need for sedation or general anaesthesia.
In general, the smaller the child the more urgent the need for diagnosis and treatment in a thoracic emergency because small children may decompensate rapidly with haemodynamic and respiratory failure.
There are many different causes of thoracic emergencies in children, some specific to a certain age group. A wide variety of different conditions may lead to thoracic emergencies in children. The most urgent and important ones involve the airways and may be life-threatening. Radiology has become increasingly important in the acute management of these emergencies. Radiography is still the most important tool and can be supplemented with ultrasound, CT and MRI. A skilled radiologist familiar with paediatric pathological conditions plays an important role in helping clinicians to ascertain the diagnosis and to start adequate treatment.
Ultrasound (US) imaging has several advantages over other radiologicimaging modalities, particularly in the emergency department (ED). It isa low cost, non-invasive, easily accessible and painless imagingmodality that can be quickly performed at the bedside of an unstable orvery ill patient. It is easily reproducible and can be repeated multipletimes without any risk. However, the greatest advantage of US overother imaging modalities, such as computed tomography (CT), is theabsence of ionizing radiation. As evidence of harmful effects ofradiation due to CT continues to increase, US is gaining greateracceptance as the imaging modality of choice in the pediatric emergencysetting. The main disadvantage of US is operator dependence. This reviewarticle highlights the use of US in evaluating common emergencyconditions in children presenting to the ED.
Intestinal malrotation is a developmental abnormality leading to adecrease in the length of the mesenteric root, predisposing the midgutto rotation. One of the most dangerous sequelae of malrotation isvolvulus, a medical emergency that causes bowel obstruction, ischemia ofand necrosis of the affected intestine. Patients can present withbilious vomiting, failure to thrive, abdominal pain and othernonspecific symptoms. Although an upper gastrointestinal (UGI) contraststudy is the gold standard of diagnosis, US can also be useful,particularly when results of the UGI study are equivocal. On US, theanatomical relationship of the superior mesenteric artery (SMA) andsuperior mesenteric vein (SMV) may be reversed (Figure 2A). Normally,the SMV is to the right of the SMA. With midgut volvulus, the SMV mayoccupy a position directly anterior or to the left of the SMA. It isimportant to note, however, that a normal SMA/SMV relationship does notexclude volvulus and the UGI study remains the imaging gold standard.Conversely, some children without volvulus may have a vertical orinverted SMA/SMV relationship.2
Although not a true emergency, pyloric stenosis is common in the ED.Pyloric stenosis occurs when hypertrophy of the pyloric muscle causesnarrowing, resulting in projectile non-bilious vomiting. The physicalexam may reveal an olive-shaped mass in the right upper quadrant of theabdomen. US is the modality of choice when suspecting pyloric stenosis.6The main diagnostic criterion is a measurement of greater than 3mm inthe thickness of the muscular layer of a single wall of the pylorus(Figure 3). Elongation of the canal greater than 12mm has also beenreported as an abnormal finding, but is less reliable due to thedifficulty in achieving reproducible measurements.7 Otherfindings include hypertrophy of the mucosa, gastric distension withactive peristalsis and redundant mucosa protruding through the antrum.Some technical maneuvers which might be useful while performing the USinclude laying the patient right-side down (allowing gas to move awayfrom the pylorus), use of sugar water to feed (not only helps in calmingthe baby but also provides a good acoustic medium for the ultrasoundbeam) and observing the pylorus during the study for any passage ofstomach content through the pyloric channel.8
Appendicitis is the most common childhood surgical emergency. Thediagnosis is challenging, particularly in younger children, potentiallyleading to a false negative diagnosis with potential for perforation andother complications. Although primarily a clinical diagnosis, imagingstudies can aid in confirmation and reducing the number of negativeappendectomies. US has a sensitivity of 88% and specificity of 94%according to a meta-analysis of studies from 1986 to 2004.12US evaluation is performed using a high frequency linear transducer andgraded compression technique. Gentle pressure is applied to the rightlower quadrant to displace normal bowel loops and ascertain the positionof the nonperistaltic cecum. The appendix usually lies just lateral tothe cecum and anterior to the iliac vessels. Positive findings ofappendicitis include an outer diameter greater than 6 mm, anoncompressible lumen arising from the base of the cecum, echogenicperiappendiceal inflammatory fat changes, an appendicolith or aperiappendiceal fluid collection (Figures 6 and 7). Enlarged mesentericlymph nodes or signs of a perforated appendix such as an abscess canalso be seen. 781b155fdc