more black sign

The more black sign is a normal finding in lateral chest x-ray, and refers to the gradual increased apparent radiolucency (blackness) of the vertebral bodies, when proceeding from upper to lower chest. This is due to the increased proportion of the chest comprised of air containing lungs over distal dorsal spine compared to the upper parts.

When the air is displaced by higher attenuation material, such as consolidation, fluid or a mass (e.g. bronchogenic carcinoma, paraspinal neurogenic tumor) then the lower thoracic vertebral bodies become more radiodense; this is referred to as the loss of the more black sign and is also known as the spine sign.

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