Tissue-mimicking gelatin-agar gels for use in magnetic resonance imaging phantoms.

A new variety of tissue-mimicking materials for use in 1H nuclear magnetic resonance (NMR) phantoms has been developed and extensively tested, principally at 10 MHz and at room temperature. The materials can be formed with a broad range of T1's and T2's representative of soft tissues. They are mixtures of various percentages of agar, animal hide gelatin, water, and glycerol. Small concentrations of formaldehyde and n-propanol prevent melting through 100 degrees C and prevent bacterial invasion. The materials are easily produced. A thorough description of compositions and production procedures is given. T1's exhibit about a 5%/degrees C rise in temperature. T2's exhibit less than a 1% rise/degrees C. Long-term (12 months) stability is exhibited both for NMR properties and for absence of fluid extrusion. Preliminary results indicate that T1's depend on the Larmor frequency in a similar way to that observed in soft tissues.