Functional Magnetic Resonance Imaging (fMRI) pushes the MRI scanner's hardware to the limits of its performance, whilst demanding exceptional stability in order to detect small changes in blood oxygenation levels.  For over 15 years MRI system stability for fMRI has been monitored using the fBIRN fMRI quality assurance protocol[1], which specifies a phantom, imaging protocol and analysis to quantify performance.

Gold Standard Phantoms is pleased to offer a spherical gel stability phantom that meets the characteristics established by the fBIRN committee.  Designed to fit within modern multi-channel MRI head coils, the FUNSTAR (Functional Stability Reference) uses a proprietary water-based, synthetic gel inside a HDPE spherical shell.  It can be used in conjunction with GSP Cloud, providing an easy-to-use, automated fBIRN stability analysis for dedicated management of quality assurance tests.

We use a synthetic polymer-based gel that offers several advantages over the traditional agar fBIRN phantom.  Being a natural product derived from seaweed, agar is subject to significant variation in gel properties and relaxation times from batch to batch.  Due to the high temperature processing that agar/agarose requires, traditional fBIRN phantoms tend to suffer from significant bubbles.  In addition, Agar is mechanically fragile and a growth medium for bacteria.

Our new gel is processed at room temperature and so is bubble free, has relaxation times that are more standardised as they are controlled by paramagnetic salts, and as the gel has some elasticity it is more mechanically stable than agar.

 [1] Report on a multicenter fMRI quality assurance protocol. Friedman and Glover. JMRI p827-839, Vol 23, Issue 6, 2006. (

Compatible MRI CoilsAll multi-channel clinical head coils currently on the market
Sphere Diameter180mm OD
Phantom contentsProprietary water-based synthetic gel doped for physiologically relevant T1/T2 values (approximately 460ms/60ms @ 3T, 20°C)
WarrantyOne year
Optional AccessoriesFoam insert for repeatable positioning in a head coil
MaterialsHDPE (shell)
Nylon (filling plug)
Nitrile (plug gasket)
IncludesLiquid crystal thermometer
Protective foam lined box

 EPI volume acquired on a FUNSTAR phantom

EPI Volume acquired on a FUNSTAR phantom

Technical data sheets