Hyperdensity of recent hemorrhage at body computed tomography: incidence and morphologic variation.

Body computed tomographic (CT) scans were reviewed in 73 patients with hematomas of recent onset. The incidence, extent, and morphologic variation of regions of hyperdensity on precontrast scans were assessed. Hyperdensity was also sought in the scans of 80 control subjects with a mass due to neoplasm or abscess demonstrated at CT. Of the 73 hematomas 55 (75%) exhibited regions of localized or diffuse hyperdensity. Only one of the 80 (1.25%) control lesions showed relative hyperdensity that could not be explained by obvious calcification, bone fragments, or diminished density of the organ of origin. Predominant hyperdensity throughout the lesion was present in 35 (48%) of the hematomas and in 16 (22%) of these was homogenous in texture. Other patterns of hyperdensity included linear shadows, hyperdense filling defects surrounded by fluid, dependent position of hyperdense fragments, and fluid fluid levels with dependent hyperdensity. Hyperdensity at CT was due to the high hemoglobin content of retracted clot or sedimented blood. The various patterns seen can be related to sequential changes occurring in blood following hemorrhage. Relative hyperdensity and its variations seen on precontrast scans are useful diagnostic signs of recent hemorrhage.