Correlation of dynamic contrast enhanced magnetic resonance imaging (DCE MRI) with 18f-fluoromisonidazole positron emission and computed tomography (18F-FMISO PET/CT) in assessing tumor hypoxia in a series of head and neck cancer (HNC) patients with nodal metastases

Abstract

6083 Background: 18F-FMISO PET/CT is a noninvasive hypoxia imaging modality. Hypoxia can develop within the tumor which typically corresponds to regions with poor blood perfusion. DCE-MRI can yield results on tumor perfusion. The present study compares hypoxic and perfusion status of HNC with nodal metastases using DCE-MRI and 18F-FMISO PET/CT imaging. Methods: 13 HNC (7 base of tongue, 5 tonsil, 1 larynx) patients with nodal metastases underwent both DCE-MRI and 18F-FMISO PET/CT scans prior to chemoradiotherapy. MRI was performed on a 1.5 Tesla GE Excite scanner. DCE-MRI studies were acquired using a fast multi-phase spoiled gradient echo sequence. Antecubital vein catheters delivered a bolus of 0.1 mmol/kg Gd-DTPA at 2 cc/s. For 18F-FMISO PET/CT,∼10.0 mCi of 18F-FMISO was administered IV and images were acquired ∼2 hours later. PET images were reconstructed; CT data were used for attenuation correction. Region of interests (ROIs) were manually drawn by a neuroradiologist. Quantitative DCE-MRI analyses were done using the 2-compartment Tofts model. The analyses calculated the pixel Ktrans(distribution rate constant), ve(extravascular-extra-cellular volume fraction), and kep(redistribution rate constant). 18F-FMISO PET/CT images were analyzed and the uptake by the tumor was scored as: no uptake (score 0); moderate-severe uptake (score 1). Semi-quantitative analysis included standardized uptake value (SUV) measurements. Statistical significance was calculated using a 2-sided Student's t-test, with p < 0.05. Results: A total of 17 nodes were analyzed. For the nodes that showed no hypoxia on PET imaging (n = 7), the mean (±SD) values were: 18F-MISO SUV (1.1 ± 03), Ktrans(0.33 ± 0.18), ve(0.53 ± 0.23), and kep(0.66 ± 0.25). For the nodes that showed moderate to severe 18F-MISO uptake (n = 10) the values were: 18F-FMISO SUV (2.8 ± 08), Ktrans(0.24 ± 0.07), ve(0.61 ± 0.13), and kep (0.43 ± 0.17). A significant lower kep for nodes with 18F-MISO uptake (p = 0.042). Conclusions: Preliminary result supports the hypothesis that the hypoxic nodes are poorly perfused nodes (lower kep values) versus nodes with no hypoxia. No significant financial relationships to disclose.