PROTON MR SPECTROSCOPY OF SQUAMOUS-CELL CARCINOMA OF THE EXTRACRANIALHEAD AND NECK - IN-VITRO AND IN-VIVO STUDIES

PURPOSE: To determine the ability of in vitro one-dimensional and two- dimensional proton MR spectroscopy to help differentiate squamous cell carcinoma of the extracranial head and neck from normal tissues and t o correlate the in vitro observations with clinical studies. METHODS: In vitro 1-D and 2-D correlated proton MR spectroscopy (11 T) was perf ormed in tissue specimens of squamous cell carcinoma of the head and n eck (n = 19), in normal tissue (n = 13), in metastatic cervical lymph nodes (n = 3), and in a squamous cell carcinoma cell line. In vivo 1-D proton MR spectroscopy (1.5 T) was performed in patients with squamou s cell carcinoma (n = 7) and in healthy volunteers (n = 7). The ratio of the areas under the choline (Cho) and creatine (Cr) resonances were calculated for 1-D proton MR spectra for the in vitro tissue studies and correlated with the in vivo studies. Data from in vitro 2-D correl ated spectroscopy were analyzed for differences in the presence or abs ence of various metabolites in samples of tumor and normal tissue. Sta tistical analysis consisted of 2 x 2 factorial repeated measures analy sis of variance (ANOVA), discriminate analysis, and chi(2) test. RESUL TS: The mean in vitro I-D proton MR spectroscopic Cho/Cr ratio was sig nificantly higher in tumor than in normal tissue. The difference betwe en the mean ratios appeared to increase with increasing echo time; All in vivo tumor Cho/Cr ratios were greater than the calculated mean in vitro tumor ratio, whereas six of the seven volunteers had no detectab le Cho and Cr resonances. Two-dimensional correlated MR spectroscopic data revealed that a variety of amino acids have a significantly great er likelihood of being detected in tumor than in normal tissues. CONCL USIONS: One-dimensional and 2-D proton MR spectroscopy can help differ entiate primary squamous cell carcinoma and nodal metastases containin g squamous cell carcinoma from normal tissue both in vitro and in vivo . In addition, 2-D spectroscopy can help identify the presence of cert ain amino acids in squamous cell carcinoma that are not detected in no rmal tissue.