The focal hepatic hot spot sign can be seen on technetium 99m sulfur colloid scans of the liver and spleen.
It occurs as a focal area of increased radiopharmaceutical uptake in the medial segment of the left hepatic lobe (segment IV) due to superior vena cava obstruction and portosystemic venous shunting between the superior vena cava and the left portal vein via the internal thoracic and paraumbilical veins. The equivalent of this sign may also be seen on contrast-enhanced CT scans as a hypervascular region. Budd-Chiari syndrome causes the hot spot sign in the caudate lobe.
There are other conditions which can result in increased uptake such as haemangioma, hepatocellular carcinoma, focal nodular hyperplasia, which if they occur in regions adjacent to falciform ligament in segment IV can mimic the focal hepatic hot spot sign.
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