Bridging the macro to micro resolution gap with angiographic optical coherence tomography and dynamic contrast enhanced MRI

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is emerging as a valuable tool for non-invasive volumetric monitoring of the tumor vascular status and its therapeutic response. However, clinical utility of DCE-MRI is challenged by uncertainty in its ability to quantify the tumor microvasculature ( μm scale) given its relatively poor spatial resolution (mm scale at best). To address this challenge, we directly compared DCE-MRI parameter maps with co-registered micron-scale-resolution speckle variance optical coherence tomography (svOCT) microvascular images in a window chamber tumor mouse model. Both semi and fully quantitative (Toft’s model) DCE-MRI metrics were tested for correlation with microvascular svOCT biomarkers. svOCT’s derived vascular volume fraction (VVF) and the mean distance to nearest vessel ( DNV ) metrics were correlated with DCE-MRI vascular biomarkers such as time to peak contrast enhancement ( r=-0.81 and 0.83 respectively, P<0.0001 for both), the area under the gadolinium-time concentration curve ( r=0.50 and -0.48 respectively, P<0.0001 for both) and k_trans ( r=0.64 and -0.61 respectively, P<0.0001 for both). Several other correlated micro–macro vascular metric pairs were also noted. The microvascular insights afforded by svOCT may help improve the clinical utility of DCE-MRI for tissue functional status assessment and therapeutic response monitoring applications.