Purpose: : To implement and evaluate a noninvasive functional MRI technique for measuring tumor tissue oxygenation changes in head-and-neck carcinoma patients.
Patients and methods: : Tissue oxygenation changes were determined quantitatively in 13 patients with head-and-neck cancer. The MR examinations were performed on a clinical MR scanner at 1.5 T. Different breathing gases (air, 2% CO(2) and 98% O(2), 100% oxygen) were administered to induce oxygenation changes. A multigradient echo sequence was used for quantification of the apparent transverse relaxation time T2*.
Results: : Pixel-by-pixel analysis of the T2* values in tumors showed a shift toward higher values corresponding to oxygenation increase and correlated with a median shift toward positive values in the DeltaT2* fraction under carbogen and oxygen breathing in most but not all patients. A slightly pronounced T2* increase breathing oxygen compared with 2% CO(2)/98% O(2) was found. Furthermore, a statistically significant difference in the heterogeneity of oxygenation changes induced by oxygen or 2% CO(2)/ 98% O(2) breathing was seen.
Conclusion: : Measurement of oxygenation changes in head-and-neck tumor patients is feasible by the presented MRI technique. Tumor oxygenation and oxygenation changes were heterogeneous among the investigated patients. To the authors' knowledge, they are the first to describe a statistically significant difference in the heterogeneity of oxygenation changes induced by oxygen or 2% CO(2)/98% O(2) breathing using a noninvasive MRI technique.