Searching for a truly "iso-metabolic" gas challenge for the use in calibrated fMRI and cerebrovascular reactivity mapping

Hypercapnia challenge has been proposed as a method for the calibration experiment because CO2 does not alter brain metabolism. However, the assumption that hypercapnia challenge is iso-CMRO2 has not been validated. This study is to investigate a gas challenge is truly iso-metabolic by adding a hypoxic component to the hypercapnic challenge (hypercapnic-hypoxia). We used TRUST MRI to monitor the subjects CMRO2 during hypercapnic-hypoxia challenge. Our data showed the neural suppression effect of hypercapnia appears to be nullified by the metabolic enhancement effect of hypoxia. We therefore propose hypercapnic-hypoxia is an iso-metabolic challenge that may be used for calibrated fMRI studies.

How to access this content:

For one year after publication, abstracts and videos are only open to registrants of this annual meeting. Registrants should use their existing login information. Non-registrant access can be purchased via the ISMRM E-Library.

After one year, current ISMRM & ISMRT members get free access to both the abstracts and videos. Non-members and non-registrants must purchase access via the ISMRM E-Library.

After two years, the meeting proceedings (abstracts) are opened to the public and require no login information. Videos remain behind password for access by members, registrants and E-Library customers.

Click here for more information on becoming a member.