The table is adapted from Table 1 in Selby et al (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6106645/), distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/). Adaptations include changes in the text of various entries and a new column with recommendations for use by EIBALL

Technique

Recommendations for use

Description of MRI technique

Pathophysiological process informed by MRI biomarker

Biomarker measured

Units of measurement

Volumetry1-4!

Enrichment biomarker / primary endpoint

measured from T1- and/or T2-weighted structural images

Key measure in patients with ADPKD but may also be important in CKD

TKV
Height-adjusted TKV
Cortical volume
Total cyst volume in ADPKD

mL
mL/m
mL
mL

Diffusion weighted imaging (DWI)5,6!

Secondary endpoint

True diffusion (D), pseudo-diffusion (tubular/vascular flow, D*) and flowing fraction (F)

Changes in renal micro- structure, oedema, or changes in renal perfusion and in water handling in the tubular compartment.

ADC
True diffusion (D)
Pseudo-diffusion (D*)
Flowing fraction (F)

mm2/s
mm2/s
mm2/s
%

DCE MRI (MR renograophy)7!

Secondary endpoint

Gadolinium-based contrast agents to change the T1 relaxation time of water in tissues. Allows measurement of perfusion and GFR.

Perfusion and filtration per unit tissue, vascularity and tubular transit times. Gd not recommended where renal function compromised.

Single kidney GFR
Tissue blood flow
Tubular flow
Filtration fraction
Tubular transit time
Tubular volume fraction

mL/min
mL/min/100mL
mL/min/100mL
%
min
%

T1 mapping8,9!

Secondary endpoint

Provides a quantitative map over the whole kidney for T1 values. T1 is a tissue-specific time variable that can distinguish different tissues.

Changes in the molecular environment, for example, water content, viscosity, temperature, fibrosis, interstitial oedema, cellular swelling.

T1
(whole kidney, cortex, medulla, cortico- medullary difference)

ms

T2 mapping9,10!

Secondary endpoint

As with T1 mapping, provides quantification of T2 as a tissue-specific time parameter. Changes with tissue water content.

Changes in the molecular environment but assumed to be more sensitive to the effects of oedema and/ or inflammation. Limited experience in human kidney disease to date.

T2
(whole kidney, cortex, medulla, cortico- medullary difference)

ms

Diffusion-tensor imaging (DTI)5,7!

Secondary endpoint

Assesses directionality of diffusion [fractional anisotropy (FA)] and allows assessment of the degree of organization in space of oriented tissues

 Changes in the microstructure that lead to a change in the preferred direction of water diffusion, for instance, tubular dilatation, tubular obstruction or a loss in the organization of medullary tubules. 

FA
 


MD (mean diffusivity)

Scale value between 0 and 1, where 0 = isotropic diffusion (equal in all directions) and 1 = complete anisotropy (diffusion in a single axis) mm2/s

BOLD MRI11,12!

Secondary endpoint

 Indirect assessment of oxygenation. Deoxygenated haemoglobin shortens the transverse relaxation time constant (T2*). Changes in renal oxygenation or changes in the microstructure of the capillary bed. T2*
R2* (1/ T2*) 		  ms
s-1

ASL13-17!

Secondary endpoint

Magnetically labelled water protons in blood that act as a endogenous tracer. Labelled images are subtracted from control images to generate perfusion maps.

Cortical perfusion

Tissue blood flow

mL/min/100g

Phase contrast MRI18,19!

Secondary endpoint

Measures blood flow in renal arteries: ‘phase shift’ is proportional to its proton velocity, allowing calculation of flow.

Resistance to flow due to downstream obstruction, or changes in systemic haemodynamics.

Renal artery blood flow (flux)
Renal artery velocity
Renal artery area

mL/s

cm/s
cm2

Magnetization transfer (MT)20!

Exploratory endpoint

The fraction of large macromolecules or immobilized cell membranes in tissue.

Shown to correlate with fibrosis in the kidney

MT ratio

%

Elastography, hyperpolarization, and 23-sodium MRI.21-23!

Exploratory endpoint

  

Technique dependent

Technique dependent

Technique dependent
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