CT gray values in Hounsfield units
corresponding to specific positions within the scanned image were obtained.
Regarding unenhanced CT evaluation, the panel said only that an attenuation value of less than 10 Hounsfield units
is more likely in a benign lesion.
Adrenal tumors with the following profile are at high risk for malignancy: 1) CT scan attenuation coefficient >10 Hounsfield units
, 2) >5 cm diameter or increase in size at reevaluation, and 3) intratumoral necrosis or evidence of capsular invasion.
The density of the intramural stratum of the halo sign varied from -75 to +33 Hounsfield units
The density of the cyst content on plain CT ranged from 10 to 20 Hounsfield units
In osteomyelitis, a difference of 20 Hounsfield units
between the 2 extremities is suggestive of marrow infiltration with edema or cellular infiltrate and can be used as a marker of early osteomyelitis.
Due to the infiltration of the submucosa by fat, the inner layer mucosa is separated from the outer layer of muscularis propria/serosa (both being of soft tissue density) by a layer of fat (of low attenuation) measuring between -18 to -64 Hounsfield Units
Carcinomas are typically >18 units, although 15% of benign masses evaluated by measuring Hounsfield units
on nonenhanced CT scans will be misinterpreted as malignant.
A mass with an attenuation value of less than 10 Hounsfield units
on an unenhanced CT scan is more likely to be benign than is a mass with a value of 10 or higher.