[Evaluation of photographic subtraction images obtained from sialograms].

Photographic subtraction used in the examination of salivary glands was compared with conventional sialography. Subtraction images obtained from the duct system of parotid glands demonstrated the same images as were obtained by conventional sialography. In duct system of the submaxillary glands, however, the conventional sialograms were clearer than those images obtained by subtraction procedures. Subtraction images could provide the outward form of salivary glands, especially in the parotid glands. In most cases, sialography with subtraction provides valuable informations in diagnosing salivary gland diseases. But, the results showed that the necessity of applying this modality must be examined carefully.