Supplementary Table 1 | Abbreviations and terminology relating to vessel-calibre MRI
Terminology
Explanation
∆B0
Bulk inhomogeneity of the magnetic field
∆R2
Change in transverse relaxation rate (typically from spin-echo DSC-MRI); a
measure of the microvessel (<10 μm) blood volume
Change in effective transverse relaxation rate (typically from gradient-echo DSCMRI); a measure of the total blood volume
Relative oxygen-saturation level
∆R2*
ΔSO2
∆χ
ADNI
Magnetic susceptibility difference between the intravascular and the
extravascular space
Alzheimer’s Disease Neuroimaging Initiative; a collaborative effort of scientists to
improve and standardize diagnosis of Alzheimer disease
Angiographic MRI
Alternative technique to conventional, contrast-enhanced angiography without
use of contrast agents; the sequence is also known as time-of-flight MRI
Arterial input function
A presumably unbiased contrast agent input to the tissue of interest
BOLD
CE MRI
Blood-oxygen-level-dependent effect; the difference in magnetic susceptibility
between oxygenated and deoxygenated blood creates image signal variations,
which can be used to measure brain activity among others parameters
Contrast-enhanced MRI
Central volume principle
Blood flow is the ratio of the blood volume to the mean transit time of tissue
DCE-MRI
Dynamic contrast-enhanced MRI; a perfusion imaging technique involving the use
of contrast agents and T1-weighted sequences that enables estimation of Ktrans
among others parameters
Imaging technique sensitive to the diffusion of water molecules within a voxel (D)
Diffusion MRI
DSC-MRI
Echo time
EPI
EPR
Dynamic susceptibility contrast MRI; a perfusion imaging technique using contrast
agents and T2-weighted or T2*-weighted sequences that enables measurement of
blood volume and blood flow among others parameters
Time from start of magnetic proton excitation to the MRI signal intensity readout
Echo-planar imaging; a very fast imaging sequence usually applied during DSCMRI
Enhanced permeability and retention
Extravasation
Leakage of the contrast agent from the intravascular to the extravascular space,
which can result in both T1 and T2 relaxation rate reducing effects
First-pass effect
The initial and transient passage of a relatively tight bolus of the contrast agent
following intravenous administration of the agent and is observed as a peak in the
relative relaxation rate signal
Fluid-attenuated inversion recovery MRI; T2-weighted MRI with water signal
suppressed (water appears black)
Paramagnetic contrast agent typically administered intravenously during
perfusion or contrast-enhanced MRI, which can leak in to the extravascular space
FLAIR MRI
Gadolinium
Gradient-echo
An MRI sequence measuring the T2* relaxation time
Gyromagnetic ratio
The ratio of magnetic dipole moment to the angular momentum
trans
K
Macrovessel MRI
Permeability surface area product, a parameter typically used as a measure of
permeability in DCE-MRI
Total blood volume from gradient-echo MRI (∆R2*)
Mean transit time
Measure of the time a certain volume of blood takes to travel through the tissue
(typically capillaries); defined as the ratio of blood volume to blood flow rate
Mesoscopic scale
Relative scale of interest at the size of microvascular networks, and typically
refers to the range between 'micro' (µm) and 'macro' (mm)
Microvessel MRI
Microvessel blood volume from spin-echo MRI (∆R2)
MION
Monte Carlo simulations
Monocrystalline iron oxide nanocompounds; a class of intravascular contrast
agents
Computer algorithms that rely on repeated random sampling
mVD
Mean blood-vessel diameter
NmVD
Normalized (tumour/reference tissue) mean blood-vessel diameter
PaCO2
Partial pressure of carbon dioxide in the blood
Paramagnetism
Physical attraction and repulsion, analogous to the forces between normal
magnets when in a magnetic field
MRI technique that measuring haemodynamic properties of tissue
Perfusion MRI
Proton excitation
To control the frequency spectrum of a radiofrequency pulse while imposing a
magnetic field gradient on proton spins
Pseudoprogression
A therapy-induced and transient increase in radiographic oedema and contrastenhancement following radiation
Q
Mean blood-vessel density
Refocusing pulse
Relaxivity
Sequence manipulation used in spin-echo MRI involving rotation of the
magnetization in the image plane
The ability to increase the relaxation rates of tissue
Repetition time
The amount of time that exists between successive radiofrequency pulses
Residue function
Analytical expression describing how the observed tracer is retained in the
vasculature
Quantum-mechanical protons
Spin
Spin dephasing
Because of static magnetic field inhomogeneity, proton spins will go out of phase
in the transverse plane when the radiofrequency pulse is switched off
Spin-echo
An MRI sequence measuring the T2 relaxation time
SPIO
Super-paramagnetic iron-oxide nanoparticles; a class of intravascular contrast
agents
SSCE
Static dephasing regime
Steady-state contrast-enhanced MRI prior to and after contrast injection; steadystate refers to a condition where the longitudinal magnetization follows a
constant cycle during imaging
A MRI condition in which diffusion is slow and can be ignored
Susceptibility
Tissue sensitivity to local magnetic field inhomogeneity, denoted χ
T1-weighted MRI
Basic MRI sequence that show differences in T1 relaxation times, this is, the time
taken for the excited magnetic state to return to its equilibrium distribution. This
process is also known as longitudinal (proton spin–lattice) relaxation. On T1weighted images, fat appears bright (hyperintense) and fluids appear black
(hypointense)
Effective transverse relaxation time (T2) based on magnetic inhomogeneity
between different tissue types
Basic MRI sequence that show differences in T2 relaxation times, that is, the decay
of the excited magnetization perpendicular to the main magnetic field. This
process is also known as transverse (proton spin–spin) relaxation. On T2-weighted
images, both fat and water-like fluids appears bright (hyperintense) and bulk
blood appears black (hypointense)
Magnetic flux density; parameter used to describe strength of MRI scanners
(typically 1.5 or 3 Tesla).
Fast low angle shot; a fast MRI data acquisition technique preferably used at high
field strengths (>3 Tesla)
Ultra-small super-paramagnetic iron-oxide nanoparticles; a class of intravascular
T2*-weighted MRI
T2-weighted MRI
Tesla
TurboFLASH
USPIO
contrast agents
VAI
Vessel architectural imaging
Vessel vortex
A parametric scatterplot of the ∆R2* and ∆R2 data used in VAI
Vf
Blood volume fraction (in percent)
VSI
Vessel size index; a quantitative measure of vessel calibre
Please also refer to http://www.mr-tip.com