In vivo proton MR spectroscopy of primary tumours, nodal and recurrent disease of the extracranial head and neck.

Benign and malignant neoplasms as well as metastatic lymph nodes of 39 patients were examined using localized single voxel magnetic resonance spectroscopy (MRS) [repetition time (TR) 1500, echo time (TE) 135) at 1.5 T. New techniques with simultaneous correction of motion artefacts during the acquisition, three-dimensional saturation pulses, respiratory triggering and smaller volume of interest (VOI) size, were applied. Ratios of peak areas under the choline (Cho) and creatine (Cr) resonances were estimated in all cases and compared with those from samples of normal tissue. Ninety one spectra were acquired in 39 patients, 63 of which were suitable for further evaluation. The smallest VOI was 0.40 cm(3). The Cho/Cr ratios in all malignant neoplasms (mean: 5.2, range: 1.7-17.8) were significantly elevated relative to those in the normal muscle structures (mean: 0.9, range: 0.2-1.4), while those in the benign neoplasms were elevated (mean: 24.4, range: 1.4-59.7) with respect to those in the malignant ones. The average Cho/Cr ratio in the metastatic lymph nodes was significantly higher (mean: 4.8, range: 3.3-5.6) than that for benign lymphoid hyperplasia (mean: 2.2, range: 1.0-3.0). MRS measurements were able to differentiate recurrent disease from post-therapeutic tissue changes in 11 out of 13 patients.