Image-defined risk factors (IDRFs)
Image-defined risk factors are imaging features seen at the time of neuroblastoma diagnosis that confer a poorer prognosis. The International Neuroblastoma Risk Group (INRG) suggested an update (2009) to the neuroblastoma staging with a list of features that, if present, upstages a patient with local disease from L1 to L2.
Crossing/extending
- from one compartment to another (e,g. chest to neck, abdomen to chest, abdomen to pelvis)
- through sciatic notch/foramen
Encasing vessels
- carotid artery
- vertebral artery
- internal jugular vein
- subclavian artery/vein
- aorta
- superior or inferior vena cava
- celiac artery
- superior mesenteric artery (including branches at the mesenteric root)
- iliac artery or vein
Compressing
- trachea
- primary bronchi
Encasing nerves
- brachial plexus roots
Invading and infiltrating
- to skull base
- into spinal canal - defined as;
- >1/3 of canal involved on an axial section
- perimedullary leptomeningeal space not visible
- signal change in the adjacent spinal cord
- costovertebral junction from T9-T12
- porta hepatis, hepatoduodenal ligament or liver
- renal pedicle or kidney
- pericardium
- duodenopancreatic block
- mesentery
Practical points
- encasement: in contact with >50% (artery or vein) or completely occluding a vein (n.b. <50% is "contact"; incomplete occlusion of a vein is "flattening")
- compression: any cross-sectional narrowing of an airway
- synchronous and metachronous tumors should be staged separately
See also
