NMR in vitro measurements: a quality control study of the RADX table-top spectrometer

A series of experiments was performed to evaluate the accuracy and reproducibility of relaxation values obtained by two RADX table-top spectrometers operating at 5 MHz (R5) and 10 MHz (R10) respectively. The output (T1, T2, and proton content) of each machine was compared (for tissue specimens and paramagnetic solutions) to reference spectrometers. In the range of tissue T1's, R5 overestimates T1 by approx. 10% and R10 underestimates by approx. 23%. For tissue specimens, the T2 output of both machines is within 3% of the reference facility. Proton content values correlate well with the % wet weight of tissues (y = .46x + 24, r = .85) but accuracy deteriorates badly if tissue T1 greater than 400 msec or T2 greater than 300 msec. The output of both machines is accurate and reproducible within 5% over the range of tissue relaxation values (biological fluids excluded).