In vivo H-1 MR spectroscopy of human head and neck lymph node metastasis and comparison with oxygen tension measurements

BACKGROUND AND PURPOSE: Current diagnostic methods for head and neck metast asis are limited for monitoring recurrence and assessing oxygenation. H-1 M R spectroscopy (H-1 MRS) provides a noninvasive means of determining the ch emical composition of tissue and thus has a unique potential as a method fo r localizing and characterizing cancer, The purposes of this investigation were to measure H-1 spectral intensities of total choline (Cho), creatine ( Cr), and lactate (Lac) in vivo in human lymph node metastases of head and n eck cancer for comparison with normal muscle tissue and to examine relation ships between metabolite signal intensities and tissue oxygenation status. METHODS: Volume-localized Lac-edited MRS at 1.5 T was performed in vivo on the lymph node metastases of 14 patients whose conditions were untreated an d who had primary occurrences of squamous cell carcinoma. MRS measurements were acquired also from the neck muscle tissue of six healthy volunteers an d a subset of the patients. Peak areas of Cho, Cr, and Lac were calculated. Tissue oxygenation (pO(2)) within the abnormal lymph nodes was measured in dependently using an Eppendorf polarographic oxygen electrode. RESULTS: Cho:Cr ratios were significantly higher in the nodes than in muscl e tissue (node Cho:Cr = 2.9 +/- 1.6, muscle Cho:Cr = 0.55 +/- 0.21, P = .00 06). Lac was significantly higher in cancer tissue than in muscle (P = .01) and, in the nodes, showed a moderately negative correlation with median pO (2) (r = -.76) over a range of approximately 0 to 30 mm Hg. Nodes with oxyg enation values less than 10 mm Hg had approximately twice the Lac signal in tensity as did nodes with oxygenation values greater than 10 mm Hg (P = .01 ). Cho signal intensity was not well correlated with pO(2) (r = -.46) but s eemed to decrease at higher oxygenation levels (>20 mm Hg), CONCLUSION: H-1 MRS may be useful for differentiating metastatic head and n eck cancer from normal muscular tissue and may allow for the possibility of assessing oxygenation. Potential clinical applications include the staging and monitoring of treatment.