31P localized magnetic resonance spectroscopy of head and neck tumors--preliminary findings.

Magnetic resonance imaging (MRI) is a powerful tool for accurate assessment of the anatomic extent of head and neck neoplasms. The development of methods for spatial localization by use of multiply tuned radio frequency coils that permit the measurement of multiple nuclear MR spectra (1H and 31P) from precisely defined volumes of interest has provided a basis for integrating spectroscopy into the clinical MRI examination. This offers a means for noninvasive monitoring of relative concentrations of mobile metabolites within a tumor. With the use of imaging to determine proper coil placement, a test-retest variance of about 17% is seen on MR spectroscopy. Data are presented from MRI/MRS studies for four head and neck lesions: (1) a squamous cell carcinoma of the lip; (2) a juvenile angiofibroma extending into the nasal cavity; (3) a massive chondrosarcoma of the nasal septum; and (4) a cervical nodal metastasis of a squamous cell carcinoma of the pharynx. Spectra are evaluated by comparison of relative concentrations of phosphorus compounds. The concentrations of phosphomonoesters and phosphodiesters are significantly higher in the neoplasms studied than in normal skeletal muscle. The developing role of integrated MRI/MRS to monitor the response of malignant neoplasm to radiation therapy is discussed.