Usefulness of the Coronal Computed Angiotomography in Diagnosis of the Isodense Chronic Subdural Hematoma

CT diagnosis of isodense chronic subdural hematoma (SDH) is difficult and often a source of false-negative results. Coronal computed angiotomographic views were very useful for the diagnosis of isodense chronic SDH, even if thin or bilateral. Seven chronic SDH cases in which the precon-trast scans demonstrated the same density as the brain were studied. Patients were placed in a supine position with the head extended and the gantry was angled at approximately 60ü to the can-thomeatal line in order to obtain coronal computed angiotomographs. Contrast enhancement was achieved by the intravenous “minimum dose bolus” injection method. Three of the seven cases showed changes secondary to mass effect such as shift of the ventricle, compression, or obliteration of the Sylvian fissures and cortical sulci. Five cases showed a high-density line with medial convexity or in parallel with the inner table of the skull and 2 cases showed a high-density dotted line away from the inner table. The high-density line or dots represented the superficial cerebral veins or cortical branches of the middle cerebral artery which were displaced medially by the hematoma. Thus, all the cases could be correctly diagnosed. When these findings are obtained, angiography may be unnecessary. Moreover, computed angiotomography is decidedly advantageous in that it is not only useful for the diagnosis of hematoma but also provides a clear and simultaneous visualization of the pathological and anatomical changes in the neighboring structures such as the cerebral parenchyma, cisterns, and ventricles. Such information is not obtainable by angiography or digital subtraction angiography.