NONINVASIVE ASSESSMENT OF TUMOR MICROENVIRONMENT USING DYNAMIC CONTRAST-ENHANCED MAGNETIC RESONANCE IMAGING AND 18F-FLUOROMISONIDAZOLE POSITRON EMISSION TOMOGRAPHY IMAGING IN NECK NODAL METASTASES

Purpose: To assess noninvasively the tumor microenvironment of neck nodal metastases in patients with head-and-neck cancer by investigating the relationship between tumor perfusion measured using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and hypoxia measured by F-18-fluoromisonidazole (F-18-FMISO) positron emission tomography (PET). Methods and Materials: Thirteen newly diagnosed head-and-neck cancer patients with metastatic neck nodes underwent DCE-MRI and F-18-FMISO PET imaging before chemotherapy and radiotherapy. The matched regions of interests from both modalities were analyzed. To examine the correlations between DCE-MRI parameters and standard uptake value (SUV) measurements from F-18-FMISO PET, the nonparametric Spearman correlation coefficient was calculated. Furthermore, DCE-MRI parameters were compared between nodes with F-18-FMISO uptake and nodes with no F-18-FMISO uptake using Mann-Whitney U tests. Results: For the 13 patients, a total of 18 nodes were analyzed. The nodal size strongly correlated with the F-18-FMISO SUV (p = 0.74,p < 0.001). There was a strong negative correlation between the median k(ep) (redistribution rate constant) value (p = -0.58,p = 0.042) and the F-18-FMISO SUV. Hypoxic nodes (moderate to severe F-18-FMISO uptake) had significantly lower median K-trans (volume transfer constant) (p = 0.049) and median k(ep) (p = 0.027) values than did nonhypoxic nodes (no F-18-FMISO uptake). Conclusion: This initial evaluation of the preliminary results support the hypothesis that in metastatic neck lymph nodes, hypoxic nodes are poorly perfused (i.e., have significantly lower K-trans and k(ep) values) compared with nonhypoxic nodes. (C) 2010 Elsevier Inc.