Quantitative and Dynamic MRI Measures of Peripheral Vascular Function

Abstract

The endothelium regulates and mediates vascular homeostasis, allowing for dynamic changes of blood flow in response to mechanical and chemical stimuli. Endothelial dysfunction underlies many diseases and is purported to be the earliest pathologic change in the progression of atherosclerotic disease. Peripheral vascular function can be interrogated by measuring the response kinetics following induced ischemia or exercise. In the presence of endothelial dysfunction, there is a blunting and delay of the hyperemic response, which can be measured non-invasively using a variety of quantitative magnetic resonance imaging (MRI) methods. In this review, we summarize recent developments in non-contrast, proton MRI for dynamic quantification of blood flow and oxygenation. Methodologic description is provided for: blood oxygenationlevel dependent (BOLD) signal that reflect combined effect of blood flow and capillary bed oxygen content; arterial spin labeling (ASL) for quantification of regional perfusion; phase contrast (PC) to quantify arterial flow waveforms and macrovascular blood flow velocity and rate; high-resolution MRI for luminal flow-mediated dilation; and dynamic MR oximetry to quantify oxygen saturation. Overall, results suggest that these dynamic and quantitative MRI methods can detect endothelial dysfunction both in the presence of overt cardiovascular disease (such as in patients with peripheral artery disease), as well as in sub-clinical settings (i.e., in chronic smokers, non-smokers exposed to e-cigarette aerosol, and as a function of age). Thus far, these tools have been relegated to the realm of research, used as biomarkers of disease progression and therapeutic response. With proper validation, MRI-measures of vascular function may ultimately be used to complement the standard clinical workup, providing additional insight into the optimal treatment strategy and evaluation of treatment efficacy.

Progress of clinical evaluation for vascular aging in humans

“…In the case of endothelial dysfunction and structural dysfunction, vascular hyperemia becomes blunted and can be measured noninvasively by a variety of quantitative MRI methods, including a blood oxygenation-level-dependent (BOLD) signal that reflects the combined effect of blood flow and capillary bed oxygen content, arterial spin labeling (ASL) for quantification of regional perfusion, phase contrast (PC) to quantify arterial flow waveforms, macrovascular blood flow velocity and rate, etc . [ 17 ] In the development of vascular aging, BOLD MRI can also be observed even in the absence of obvious ASCVD. [ 18 , 19 ] Some studies have also found that there is an association between ASL-based measurement and the occurrence and severity of peripheral vascular disease.…”

Multimodal Functional Imaging for Cancer/Tumor Microenvironments Based on MRI, EPRI, and PET

“…For BOLD MRI, several review papers were already published and described technical details with numerous applications in functional MRI [ 80 , 81 , 82 ]. Paramagnetic deoxyhemoglobin has a ferrous iron on the heme.…”

The “Hitchhiker’s Guide to the Galaxy” of Endothelial Dysfunction Markers in Human Fertility

“…Even magnetic resonance imaging (MRI) has been increasingly used for assessing endothelial functioning [ 71 ]. Quantitative, dynamic, non-contrast MRI studies have been developed, including the blood oxygen level-dependent (BOLD) imaging, the arterial spin labelling (ASL), the phase contrast (PC), the MRI-measured PWV, the luminal FMD, and the dynamic MRI oximetry [ 71 ]. These innovative approaches provided the opportunity to measure endothelial dysfunctions in human sites not easily accessible.…”