Increased salivary gland density on contrast-enhanced CT after head and neck radiation.

In an attempt to determine whether radiation therapy leads to an increased density of salivary glands on subsequent contrast-enhanced CT, 109 CT scans from 78 patients with head and neck tumors were reviewed. The density of parotid and submandibular glands was subjectively evaluated (compared with adjacent muscle) and correlated with treatment including surgery, chemotherapy, and radiation. Density of the parotid and/or submandibular glands was found to be significantly associated with previous irradiation on contrast-enhanced scans (p less than .05). One or both glands were denser than normal in seven (44%) of 16 patients who received only radiation therapy and in eight (38%) of 21 who received chemotherapy and radiation therapy, compared with only two (10%) of 20 patients who received chemotherapy alone and two (4%) of 52 patients who received neither. The type or amount of irradiation, type of chemotherapy, or timing of the CT scan after the initiation of treatment was not found to be significant. We conclude that the density of the parotid and/or submandibular glands on contrast-enhanced CT is frequently increased after radiation therapy for tumors of the head and neck.