Table 2.

Standardization of confounding factors in vascular testing (adapted from (Van Bortel et al. (2002)).

Confounding factors	In practice
Room temperature	Document. Be aware of increase in temperature with prolonged scanning and plan experiments with this in mind.
Time of day	Similar time of day for repeated measurements.
Smoking	Avoid for 3 h prior
Food	Avoid for 3 h prior
Caffeine	Avoid for 3 h prior (and exclude those with very high intake).
Alcohol	Avoid for 10 h prior
Menstrual cycle	Stage in cycle recorded Aim for similar stage in repeat measurements
Height, weight	Record
Visual stimulation Speaking	Ask patients not to speak and to keep their eyes shut during reactivity testing
Haematocrit	Record
Medication	Record Consider withholding/excluding vasoactive medication
Sleeping	Patient should not be allowed to sleep during the scan
Cardiac rhythm	Consider if this may influence data