Table 2.

Final consensus statements

#	Statement	Abstentions (%)	Agreement (%)
1. Patient preparation
1.1	Subject should be scanned in a normal hydration status when clinically appropriate	24	100
2. Hardware
2.1	Both 1.5 T and 3 T are adequate field strengths	0	87
2.2	The body coil should be used as transmitter coil	6	93
2.3	Body phased-array coils should be used as receive coils	0	94
3. Labeling strategy
3.1	Both PASL:FAIR and PCASL are adequate labeling strategies	6	93
3.2	Single time point acquisitions are recommended for simplicity of acquisition and data analysis	6	86
3.3	Multiple time point acquisitions require a longer acquisition time and more complicated processing. However, they can provide measurements of perfusion and ATT that can be useful if delayed arrival time is suspected in a clinical population	6	100
4. FAIR labeling parameters
4.1	A FOCI pulse should be used for the selective inversion to optimize the inversion slice profile	19	92
4.2	The selective slab should be carefully positioned, excluding the aorta	6	100
4.3	The selective inversion slab thickness should equal the imaging slab thickness + [10–20] mm	13	86
4.4	In single-TI acquisitions, an inversion time of 1.8–2.0 s is recommended	10	89
4.5	In single-TI acquisitions, an approach for controlling the temporal width of the bolus (QUIPSS II or Q2TIPS) must be used to quantify perfusion	25	100
4.6	A bolus duration (TI1) of 1.0–1.2 s is recommended	25	92
4.7	In single-TI acquisitions, a minimum of 20 ASL pairs is recommended	10	89
5. PCASL parameters
5.1	An unbalanced version of PCASL is preferred due to its lower sensitivity to off-resonance effects	38	80
5.2	A labeling time of 1.5–1.8 s is recommended	10	100
5.3	The labeling plane should be oriented approximately perpendicular to the aorta	13	100
5.4	The labeling plane should be positioned at approximately 8–10 cm from the centre of the kidney, in the superior direction	14	94
5.5	Hanning RF pulses are recommended	31	100
5.6	An RF pulse duration of 500 μs is recommended	25	100
5.7	Pulse spacing (from the centre of one pulse to the centre of the next) of 1000 μs or shorter is recommended	31	100
5.8	Average B1 of 1.6 μT is recommended	27	100
5.9	Average gradient (Gave) of 0.4–0.6 mT/m is recommended	25	92
5.10	Gmax to Gave Ratio of 6–7 is recommended	40	100
5.11	In single PLD acquisitions, a PLD of 1.2–1.5 s is recommended	19	100
5.12	In single-PLD acquisitions, a minimum of 20 ASL pairs is recommended	14	83
6. Readout
6.1	A 2D single-slice acquisition scheme is recommended as the default renal ASL method	10	95
6.2	Multislice 2D acquisition schemes are recommended for applications that require extended kidney coverage	5	100
6.3	3D acquisition schemes represent a promising alternative to 2D multislice schemes but are not recommended as the default method for extended kidney coverage due to limited clinical experience with 3D schemes	10	95
6.4	Spin-echo EPI is the preferred readout for 2D single-slice acquisitions	5	75
6.5	bSSFP and single-shot RARE are adequate alternatives to EPI for 2D single-slice acquisitions	14	94
6.6	Spin-echo EPI is the preferred readout for 2D multislice acquisitions	14	83
6.7	Coronal oblique slices (along the major axis of the kidneys) are preferable for renal ASL	6	93
6.8	The recommended slice thickness in 2D acquisitions is 4-8 mm	19	100
6.9	The recommended slice thickness in 3D acquisitions isss 3-6 mm	13	100
6.10	The recommended in-plane resolution is 2-4 mm	0	93
6.11	Undersampling methods, such as partial Fourier and parallel imaging at moderate acceleration factors (up to R = 2) may be used	19	100
6.12	The recommended TR (including labeling + readout) is 4–6 s	0	94
7. Other sequence details
7.1	Pre and post-inversion saturations are recommended for FAIR labeling schemes	14	100
7.2	Background-suppression is recommended for renal ASL	5	80
7.3	Breath-hold scans are not recommended for clinical renal ASL	0	94
7.4	Renal ASL scans under free breathing are preferred	0	76
7.5	Respiratory triggering can be advantageous to minimize the effects of kidney motion at the expense of scan time	5	95
7.6	Fat suppression is recommended for renal ASL	5	90
8. Data preprocessing
8.1	Retrospective image registration is highly recommended for renal ASL	13	100
8.2	Outlier rejection is recommended for renal ASL	0	100
9. Quantification
9.1	M0 acquisition is mandatory	0	94
9.2	Using a single-compartment model with assumed blood T1 for quantification is recommended for robustness and simplicity	7	100
9.3	A two-compartment model with separate transit time and tissue T1 measurements is a viable alternative to the single-compartment approach but requires more complex acquisition/analysis methods and therefore is currently not recommended as the default renal ASL approach	10	95
9.4	Tissue-blood partition coefficient = 0.9 mL/g [82–84, 97]	5	90
9.5	Assumed blood T1 at 3 T = 1.65 s [98]	0	100
9.6	Assumed blood T1 at 1.5 T = 1.48 s [98]	13	93
9.7	Labeling efficiency PASL = 95% (neglecting background suppression loss)	6	100
9.8	Labeling efficiency PCASL = 85% (neglecting background suppression loss)	13	86
9.9	When background suppression is used, the labeling efficiency needs to be adjusted based on the number of background suppression pulses	19	100
9.10	Regions of interest selection should be performed manually as the default approach. Semi-automatic methods may be used if local expertise is available (e.g. using T1 maps) but require extensive validation	0	100
9.11	Region of interest selection should be performed based on the ASL M0 image or a separately acquired structural dataset	6	93
10. Data analysis/reporting
10.1	Cortical renal blood flow values (not whole-kidney) should be reported, separately for left and right kidney	0	100
10.2	Medullary renal blood flow values are not considered reliable with current measurement approaches	14	89