Initial results with prereconstruction dual-energy computed tomography (PREDECT).

Prereconstruction dual-energy computed tomography (PREDECT) produces rigorously exact reconstructions that accurately separate the total attenuation coefficient into two values, representing the Compton and photoelectric contributions. The images are obtained without polychromatic distortion and with an acceptable dose. PREDECT was used to scan objects and solutions of varying atomic number and electron density, specimens of normal and pathologic brain and other body tissues, and nine patients. The values for Compton and photoelectric attenuation of the different specimens were distinctive enough to provide "tissue signatures" of potential clinical usefulness. Eight of the nine patients studied provided acceptable images, which produced some tissue characterization. PREDECT appears to represent an advance over the previously used postreconstruction methods; areas of greatest potential are differential diagnosis, improved detection of abnormalities, and elimination of the polychromatic artifact.