Education, tips and tricks to help you conduct better fMRI experiments.
Sure, you can try to fix it during data processing, but you're usually better off fixing the acquisition!

Friday, August 15, 2014

QA for fMRI, Part 3: Facility QA - what to measure, when, and why

As I mentioned in the introductory post to this series, Facility QA is likely what most people think of whenever QA is mentioned in an fMRI context. In short, it's the tests that you expect your facility technical staff to be doing to ensure that the scanner is working properly. Other tests may verify performance - I'll cover some examples in future posts on Study QA - but the idea with Facility QA is to catch and then diagnose any problems.

We can't just focus on stress tests, however. We will often need more than MRI-derived measures if we want to diagnose problems efficiently. We may need information that might be seem tangential to the actual QA testing, but these ancillary measures provide context for interpreting the test data. A simple example? The weather outside your facility. Why should you care? We'll get to that.

An outline of the process

Let's outline the steps in a comprehensive Facility QA routine and then we can get into the details:

  • Select an RF coil to use for the measurements. 
  • Select an appropriate phantom.
  • Decide what to measure from the phantom.
  • Determine what other data to record at the time of the QA testing.
  • Establish a baseline.
  • Make periodic QA measurements.
  • Look for deviations from the baseline, and decide what sort of deviations warrant investigation.
  • Establish procedures for whenever deviations from "normal" occur.
  • Review the QA procedure's performance whenever events (failures, environment changes, upgrades) occur, and at least annually.

In this post I'll deal with the first six items on the list - setting up and measuring - and I'll cover analysis of the test results in subsequent posts.