MRI Changes of Acute Kidney Injury in COVID-19

Global organ structure will be assessed through structural T1- and T2-weighted MRI scans which will provide information about automated segmentation and volume assessment of whole kidney (and both cortex and medulla) as well as other abdominal organs (including liver and spleen). Global organ structure will also be assessed through longitudinal (T1) and transverse (T2) relaxation time mapping. T1 and T2 increase with tissue inflammation, oedema and fibrosis. A respiratory-triggered inversion recovery (IR) spin-echo echo-planar scheme will be used for abdominal T1 mapping and a Gradient and spin echo (T2-GraSE) scheme for abdominal T2 mapping.

R2* data will be acquired using a multi-echo fast field echo (mFFE) scheme to assess thrombi. Conventionally R2* mapping is used as a measure of oxygenation, but R2*is likely to be altered by other factors in COVID-19, including oedema and small vessel thrombotic processes.

Mean transit time and perfusion depicting changes in microvascular blood flow and large vessel flow/thrombosis will be determined using a FAIR labelling scheme with a multi-slice spin-echo echo-planar imaging readout and multiple labelling delay times.

Correlations between MRI measures (Cortical T1, ASL-perfusion, T2, R2*) with estimated glomerular filtration rate (ml/min/1.73m2).

Correlations between MRI measures (Cortical T1, ASL-perfusion, T2, R2*) with urine albumin creatinine ratio (mg/mmol) and urine protein creatinine ratio (mg/mmol).

Correlations between MRI measures (Cortical T1, ASL-perfusion, T2, R2*) with the mental component score. A score between 0 and 100 is calculated from the 36-Item Short-Form Health Survey; the higher the score, the better the quality of life mental domain.

Correlations between MRI measures (Cortical T1, ASL-perfusion, T2, R2*) with the physical component score. A score between 0 and 100 is calculated from the 36-Item Short-Form Health Survey; the higher the score, the better the quality of life physical domain.

Correlations between MRI measures (Cortical T1, ASL-perfusion, T2, R2*) with the health state score calculated from the European Quality of Life 5-Dimensions questionnaire. The health state score ranges from -0.285 (for the worst health state) to 1 (for the best health state).

Correlations between MRI measures (Cortical T1, ASL-perfusion, T2, R2*) with the visual analogue score from the European Quality of Life 5-Dimensions questionnaire. The visual analogue score uses a thermometer-like scale numbered from 0 to 100; the higher the score, the better the health state.

Correlations between MRI measures (Cortical T1, ASL-perfusion, T2, R2*) with the fatigue score from the Fatigue Severity Scale, a 9-item questionnaire scored on a 7-point scale (minimum score=9; maximum score=63); the higher the score, the greater the fatigue severity.

Correlations between MRI measures (Cortical T1, ASL-perfusion, T2, R2*) with the fatigue score from the Visual Analogue Fatigue Scale, which uses an horizontal line scale numbered from 0 to 10; the higher the score, the higher the fatigue.

Correlations between MRI measures (Cortical T1, ASL-perfusion, T2, R2*) with skin autofluorescence levels (arbitrary units) measured with the validated Autofluorescence Reader Standard Unit (SU) version 2.4.3 (AGE Reader SU, DiagnOptics Technologies BV, Aarhusweg 4-9, Groningen, The Netherlands).

Mean change in mental component score. A score between 0 and 100 is calculated from the 36-Item Short-Form Health Survey; the higher the score, the better the quality of life mental domain.

Mean change in physical component score. A score between 0 and 100 is calculated from the 36-Item Short-Form Health Survey; the higher the score, the better the quality of life physical domain.

Mean change in health state score calculated from the European Quality of Life 5-Dimensions questionnaire. The health state score ranges from -0.285 (for the worst health state) to 1 (for the best health state).

Mean change in visual analogue score from the European Quality of Life 5-Dimensions questionnaire. The visual analogue score uses a thermometer-like scale numbered from 0 to 100; the higher the score, the better the health state.

Mean change in fatigue score as assessed by the Fatigue Severity Scale, a 9-item questionnaire scored on a 7-point scale (minimum score=9; maximum score=63); the higher the score, the greater the fatigue severity.

Mean change in fatigue score as assessed by the Visual Analogue Fatigue Scale, which uses an horizontal line scale numbered from 0 to 10; the higher the score, the higher the fatigue.

Mean change in skin autofluorescence levels (arbitrary units) measured with the AGE Reader.

Assessment of kidney disease progression defined as decrease in estimated glomerular filtration rate (eGFR) of ≥25% associated with a decline in eGFR stage.

Recording of the number of participants who developed any cardiovascular events.

Correlations between MRI measures (Cortical T1, ASL-perfusion, T2, R2*) with all-cause mortality using multi-variable Cox proportional hazards models.