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RC 1612 - Imaging children with cancer

Saturday, March 4, 16:00 - 17:30 Room: O Session Type: Refresher Course Topics: Nuclear Medicine, Oncologic Imaging, Paediatric Moderator: C. Balassy (Vienna/AT) Add session to my schedule In your schedule (remove)

A-763

A. Imaging of abdominal masses at diagnosis: clues for benignity vs malignancy

Ø. E. Olsen; London/UK

Learning Objectives

1. To become familiar with clinical characteristics and imaging features of a mass suggesting benignity.
2. To emphasise clinical and imaging manifestations of abdominal malignancies.
3. To learn how to report according to international standards.

Abstract

Radiology is a probabilistic discipline since there is no test-diagnosis pair with perfect sensitivity and specificity. This also means that the definition of what distinguishes a likely benign vs. a likely malignant lesion must change depending on pre-test likelihoods. In most instances, the accuracy of imaging to make this distinction is low, hence the pretest likelihood is more important than the imaging findings themselves. So, for example, if you work in a general hospital you will very rarely see malignant tumours in children, so you are rarely wrong calling all lesions benign. The opposite is true in a specialised paediatric cancer centre. Similarly, it is possible to make decision rules based on clinical presentation, age, etc. There are, however, a few clues that often help shift these pre-test likelihoods, albeit none is absolute. Almost always benign: 1) origin splenic, hepatic in children <3 months of age, gastrointestinal, dermal. 2) Perfusion pattern similar to organ of origin. 3) Uptake of tissue-specific contrast agent. 4) Typical appearance of hamartoma. 5) Sharply demarcated lytic bone lesions. Almost always malignant: solid tissue with any pattern of growth. Most other characteristics must be interpreted with caution. Specifically, the following are NOT good predictors: 1) Doppler features (a vascular tumour is not always a haemangioma). 2) Heterogeneity (teratomas may contain malignant elements). 3) Containment (renal tumour are typically very large yet rarely breach the renal capsule). 4) Lack of enhancement (embryonal tumours often do not enhance much). 5) Apparent diffusion coefficient.

A-764

B. From whole-body MRI to MR/PET

W. Hirsch; Leipzig/DE

Learning Objectives

1. To understand differences and pitfalls of whole-body MRI and MR/PET in children compared to adults.
2. To compare PET/MRI to PET/CT.
3. To discuss the impact of whole-body MRI and PET/MRI in paediatric oncology.

Abstract

Whole body MR (WB-MR) and PET-MR are suitable methods to determine precisely the spread pattern of diseases. Whole body MRI is routinely used in paediatric oncology. It is very effective in the initial staging in multifocal oncological diseases. In restaging, the PET MRI has been shown to be more specific and sensitive in many diseases than the WB-MR. The new hybrid technique of whole body PET-MR leads, particularly in children, to significantly less radiation compared to whole body PET-CT. The radiation dose derives only from the PET part. The radiation exposure in PET-MR equals 3-4 mSv in 3D-mode. In contrast to this, a typical effective dose for a child on PET-CT is about 25 mSv. Therefore, it is likely that by establishing PET-MR 80% of radiation exposure can be prevented compared to PET-CT. A lot of radiotracers are used for PET imaging. For paediatric PET-MR mainly 18F-fluorodeoxyglucose (18F-FDG) and 11C-methionine (11C-MET) are used. However, other tracers are available, e.g. 68Ga-DOTATOC for neuroendocrine tumours or meningioma. Using case studies, typical clinical indications and findings of hybrid imaging in children will be demonstrated, such as PET-MR for oncologic issues, or to locate biopsy areas for brain tumours (hotspot-biopsy). However, the diagnostic usefulness and impact on patient management (“diagnostic imaging efficacy”) must be weighed against the exposure of radiation and also the costs.

A-765

C. Imaging of complications of therapy

A. S. Littooij1, C. Granata2; 1 Utrecht/NL 2 Genoa/IT

Learning Objectives

1. To become familiar with short- and long-term complications of therapy.
2. To understand complications of surgery, radiotherapy and drug toxicity.
3. To emphasise the effects of immunosuppression in children undergoing chemotherapy.

Abstract

Cancer is the second most common cause of death among children in the Western world, surpassed only by accidents. Although incidence rates have remained fairly stable, advances in treatment of childhood cancer have resulted in significant improvement of survival, reaching nearly 80%. However, all cancer treatment modalities (chemotherapy, surgery, radiation therapy or stem cell transplantation) are associated with toxic effects, which range from mild to debilitating and can be seen in almost every part of the body. Roughly, 75% of childhood cancer survivals will experience one or more chronic health condition. Despite advances in treatment and supportive care, 15% of deaths within the first 5 years from diagnosis are due to treatment-related complications. Many of the treatment related adverse effects are evaluated by imaging. Radiologists have a pivotal role in detecting these sequelae. Increased awareness of treatment-related adverse effects would permit more effective surveillance, opportunity for earlier intervention with subsequent improved quality of life. The acute side effects consist of infectious complications due to treatment-related immunosuppression or irritant effects. Common complications occurring after treatment include neurocognitive defects, endocrine dysfunction, pulmonary complications, cardiomyopathy, hepatic dysfunction, renal failure, osteonecrosis, scoliosis, graft-versus-host disease and development of secondary malignancies. This lecture will highlight the most common complications in different organ systems with emphasis on those in which imaging plays an important role.

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