Superscan

This bone scan of a patient with metastatic breast carcinoma demonstrates the “superscan” phenomenon. Tracer uptake is so avid in bone that there is almost no renal excretion - the kidneys are barely visualised.
Causes of superscan are as follows: renal osteodystrophy; osteomalacia; hyperparathyroidism; hyperthyroidism; diffuse skeletal metastases; myelofibrosis; haematological malignancy; extensive Paget’s disease.
Of these, skeletal metastases is the most common cause.
Caution should be taken - absent renal tracer may also be due to renal failure - check for bladder tracer, which is present in a superscan.
Reference: Dahnert W. Radiology Review Manual, 5th edition. Lippincott, Williams and Wilkins 2003
Credit: Dr Laughlin Dawes
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