Quality assurance fMRI
& Standardization

Protocol Adherence

Imaging studies conducted at AFI adhere to a comprehensive protocol that operationalizes all study specific procedures including bioinfomatic standards, optimized acquisition parameters, manualized experimental procedures and standardized quality assurance checks.  Protocol adherence is monitored using pencil and paper documentation as well as automated data derived quality checks.           

Participant Management

AFI is a dedicated research facility and has been designed to provide a pleasant, professional and efficient experience for each research participant.  Space is available for consenting procedures, participant training and post scan debriefing.  All training rooms include stimuli delivery computers and mock response devices.  Additional space is available for behavioral assessment and physical examination including blood draw.  An AFI participant will experience a degree of support, organization and expertise that reduces anxiety and minimizes participant attrition delivered within a standardized protocol that ensures a shared experience amongst the study cohort.

Stimuli Delivery
AFI provides stimuli delivery system (link to system hardware specs in Equipment page listing projector, avotec system, and FORP) that is robust, redundant and monitored for Quality Assurance (QA).  The system is calibrated weekly and continuously monitored to ensure adherence to study protocol parameters. At AFI each imaging session begins with a stimuli system diagnostic test to ensure full functionality and to monitor QA. Custom stimuli delivery systems (intravenous, haptic, gustatory, olfactory, etc) can be implemented to meet study specific needs.

Scanner Performance
At AFI scanner performance is monitored continuously to ensure the highest data quality.  First, daily phantom data sets (structural and functional) are acquired and an automated analysis procedure estimates signal to noise ratio (SNR) and detect unusual spike noise.  Results are plotted (updated daily on website) to detect trends and evaluate system performance.  Second, all data collected at AFI is checked into our image management database (QLUX link to qlux page) and undergoes automated QA assessment within minutes of data acquisition.  These QA data are also plotted and inspected for trends both across and within study protocols.  Our physicist and Siemens Uptime personnel are on-call to evaluate and immediately address any anomalies detected by AFI’s quality assurance program.

Artifact Management

Participant Motion: AFI considers motion artifact a critical issue that can be minimized though participant training and instruction, effective head stabilization, and continuous participant monitoring. AFI has found the following strategies effective in managing motion artifact:

• Ensure that a simple and clear understanding of the effects of motion is communicated to participants during the training and instruction phase of the study. 

• AFI employs an optimal head stabilization devices for use with Siemens product headcoils and Avotec headphones that results in comfortable but firm head restraint.

• A single strip of micropore tape attached to the headcoil and the participant’s forehead provides immediate feedback to the participant if they move.

• Our RF window affords careful observation of the participant through the entire length of the bore allowing us to monitor subjects gross body motion and provide feedback when needed.

• On line inspection of time series during acquisition is performed to provide qualitative assessment of subject motion.

• AFI’s realtime capabilities allow for immediate quantification of subject motion by rapidly applying motion correction algorithms and calculating summary metrics such as mean relative displacement.

Magnetic Field Inhomogeneity: Residual disturbances in the B0 field are exacerbated by head size and motion during a study.  This inhomogeneity spatially distorts gradient echo EPI images.  AFI routinely acquires a B0 field map for all subjects, which is utilized during post processing to correct spatial distortion cause by variability in the magnetic field.

Physiological Noise: Respiration and cardiac cycle contribute to the noise component of gradient echo EPI images. AFI routinely records respiration and pulse using Siemens physiological monitoring sensors. Raw physiological data is synchronized with time series acquisition using a time stamp at each repetition.  These data are incorporated into the GLM analysis as nuisance variable regressors effectively improving SNR by accounting for noise.