purple-radiotracer in the blood stream, in the iliac vessels

red-increased blood flow in a ring around the torsed right testis, which appears as a low uptake central rounded area

blue-normal moderate blood flow to the left scrotum and testis

This is a nuclear medicine scan to detect blood flow. Before introduction of high resolution scrotal ultrasound, this test was commonly used to detect testicular torsion in patients with acute scrotal pain and no history of trauma. This study has a moderately high radiation dose, so it is no longer used, since ultrasound has no radiation.