[Magnetic resonance imaging of small nasopharyngeal tumors]

Magnetic resonance (MR) images of 9 patients with a small nasopharyngeal tumor were examined, and among them three cases were evaluated with Gd-DTPA enhancement technique. All cases showed no asymmetry of parapharyngeal space, but they presented neck lymph nodes swelling. These cases were proved malignant by surgical procedures and the blind biopsy. MR findings of levator and tensor veli palatini muscles and retropharyngeal lymph nodes were retrospectively evaluated in correlation with endoscopic examination and biopsy. In six cases among 9 patients, MR images demonstrated tumors on the lateral wall of nasopharynx. Infiltration of levator veli palatini muscle was an especially important earlier sign of nasopharyngeal tumor invasion because the levator veli palatini muscle belongs to the intrapharyngeal muscle group. Endoscopic examination could not reveal any abnormal lesion in three cases among these 6 cases. No definite signal intensity difference between tumor and pharyngeal mucosa was shown on both T1 and T2 weighted images. But the normal pharyngeal mucosa had demonstrated higher intensity than tumor with Gd-DTPA administration. So the enhanced nasopharyngeal MR imaging made the clear intensity difference between tumor and muscle tissue. It was the conclusion that MR imaging was superior to X-CT in detecting small nasopharyngeal tumor.