NeuroblastomaBMJ 2017; 357 doi: https://doi.org/10.1136/bmj.j1863 (Published 03 May 2017) Cite this as: BMJ 2017;357:j1863
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The author is correct that when there is suspected spinal cord involvement by neuroblastoma MR is the preferred diagnostic imaging technique given its better visualization of the spinal canal[1-3]. Both CT and MR are widely used imaging modalities for neuroblastoma, and either one can be utilized for both initial imaging or to assess disease response. CT has the benefit of not requiring sedation and, depending on the local hospital’s resources, may be more readily available than MR. If there is concern for respiratory compromise secondary to a mediastinal mass, avoiding the sedation and time necessary for an MR may be warranted, and CT would be preferable. While radiation exposure is always a concern, modern CT scanners with optimized pediatric scan protocols lead to very small exposure risk, which should be weighed against benefits above.
Ultrasound is a widely available imaging technique that is often initially performed when a patient presents with a suspected abdominal mass. The limitations of ultrasound are its potential to not adequately identify highly calcified tumors, as well as a high rate of discrepancy between different interpretations of the images. A patient presenting with a primary mediastinal neuroblastoma needs a thorough and rapid evaluation of possible soft tissue and nodal metastatic sites. More detailed imaging of the abdomen than ultrasound can provide may thus be warranted.
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Competing interests: No competing interests
Your recent clinical update on neuroblastoma contains one radiological image which should really be out of date, particularly in a supposedly state-of-the-art review paper (1). The image in question is a coronal CT image of the chest and abdomen showing a large superior mediastinal neuroblastoma, probably in a young child as that is the peak age for neuroblastoma occurrence (the age was not supplied, the mass is on the left not right as stated in the figure legend).
What else is wrong with this image? As the authors correctly mentioned an ultrasound scan of the abdomen should form part of the work-up in all patients with suspected neuroblastoma. If an ultrasound of the abdomen had taken place in the case in question, an abdominal mass would have been excluded in this patient and there would have been no need for the abdominal component of the CT scan. CT scanning, with its generally acknowledged relatively high radiation burden, is ideally avoided where possible in children who are believed to be more radiation sensitive than adults (2). There is a better alternative. MRI is preferred over CT for such mediastinal neuroblastic tumours because it better evaluates for spinal canal involvement, for bone marrow disease and it is superior to CT in assessing chest wall invasion. The child in the article’s image would have been better served with a thoracic MRI scan, which would thus have afforded more useful information to the paediatric surgeon, simultaneously avoiding the hazards of ionising radiation from a chest CT. One could argue that MRI of the chest in a 2-4 year old child requires a general anaesthetic (GA) but the hazards of a GA in a well child are minimal (the trachea is not compressed in the one image supplied).
In summary, the hazards of CT scanning in children are at best unknown and should be avoided where possible, doing a CT of the abdomen in this particular setting was unnecessary and MRI in this context would have been a better test. An MR image would have set a better standard for your readership and indeed the parents of children with neuroblastoma.
1 Shohet J, Foster J. Neuroblastoma. BMJ 2017: 357; 234-236.
2 Pearce MS, Salotti J, Little MP et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet 2012: Aug 4; 380 (9840); 499-505.
Kieran McHugh, FRCR FRCPI
Consultant Paediatric Radiologist
Competing interests: No competing interests