The Assessment Of Tumoral Oxygenation Using BOLD FMRI With Non-hemodynamic Response Function Analysis In Comparing With Histopathological Findings In Rats Bearing C6Glioma

Purpose: A blood-oxygen-level-dependent functional magnetic resonance imaging(BOLD fMRI) using carbogen (93%oxygen and7%carbon dioxide gas mixture)inhalation in combined with a non hemodynamic response function (HRF) analyzed imagepost-processing algorithm had been developed for in vivo non invasive monitoring of thepotential re-oxygenation area within the rats subcutanous C6glioma. Its reliability andfeasibility was then assessed preliminary in comparing with the histopathological findings.Methods:1.17Wistar rats (no any gender limitation) were performed C6glioma cellssubcutaneous plant for tumor cultivation.2. Tumoral MR image acquisition using1.5Tsuperconductivity MR imaging system and Micro47coil, including:①Non-enhancedT2WI–TSE、T1WI–TSE scans, following by enhanced3D T1WI-FFE and T1WI-TSEscans.②Single-shot gradient-echo echo-planar-imaging (GE-EPI) T2*weighted-imagingwith carbogen inhalation.3. Establishing a non-HRF analyzed image post-processingalgorithm for generating “tumoral oxygenation map” according to the significantdifference in the intensity level before and after carbogen inhalation.4. After image dataacquisition, whole subcutaneous tumor specimen were acquired for pathologicalexamination whose section plane was in consistent with that of “tumoral oxygenation map”.5. Evaluation the spatial comformity of the “hypoxia area” and “oxygenation area” on the“tumoral oxygenation map” in comparing with the necrotic and the solid area representingon pathological section.Results:1. All17rats were successfully beared one subcutenous tumor, whose meandiameter were38.49mm, after3-5weeks of C6glioma cells plant.2. The BOLD signalintensity changed significantly before and after carbogen inhalation in tumoral parenchyma area (P＜0.01); no significant changes was found in tumoral necrosis area (P＞0.05),however.3. The location and range of the obvious oxygenation area as well as hypoxiaarea representing on “oxygenation map” within tumors was corresponding with theparenchyma area and the necrosis area representing on the section, respectively.Conclusion: BOLD fMRI using carbogen inhalation in combined with non-HRFanalysed image post-processing could identify reliably non-invasive the oxygenationvariation within glioma in vivo. It could also monitor non invasive the potentialre-oxygenation area within the glioma dynamically. This functional imaging method couldbe useful to the selection of patients with glioma that are suitable for oxygen-sensitizedradiotherapy.This dynamic detection in accordance with change of oxygenation within theglioma could be conducive to individual treatment planning for improving the therapeuticeffect.