Terranova-MRI Features
- Lightweight and portable, the entire system weighs less than 15 kg.
- 3 Imaging Gradient Coils for 3D MR Imaging.
- A fourth gradient coil for diffusion measurements.
- Specially designed for teaching, includes a Student Experiment Guide.
- Pulsed NMR & MRI spectrometer.
- Easy to setup, simple USB interface between spectrometer and PC.
- Easy to use Terranova-MRI software.
- Customisable macro driven interface.
- 3D, 2D and 1D Imaging experiments using Spin-echo, Gradient echo for FBP.
- FID, Spin echo, T1, T2 and PGSE experiments.
To download the Terranoval-MRI Earth's Field MRI Brochure in PDF format click here.
Terranova-MRI Experiments
CPMG in the Earth's field
A single shot T2 measurement of water using the CPMG sequence.
Carr-Purcell-Meiboom-Gill (CPMG) is a powerful NMR experiment that employs multiple 180? re-focusing RF pulses to generate a train of spin-echo signals whose amplitudes decay according to the T2 time constant of the sample. This experiment can be implemented at Earth?s field on the Terranova system. Software control of the phase of the excitation (90?) pulse and the re-focusing (180?) pulses allows the user to acquire both a CP echo train and a CPMG echo train, illustrating the inherent tip angle error correction of the latter sequence.
A representative CPMG experiment acquired of a 500mL sample of tap water. The echo time, the time between the re-focusing pulse and the centre of the echo signal, was 110ms. The apparent T2 was found to be 1.64s ? 0.02s.
Observe J-coupling in the Earth?s Field
Scalar spin-spin coupling (also called J-coupling) provides structural detail within a NMR spectrum. J-coupling is the result of an indirect interaction between nuclei. The heteronuclear J-coupling between 1H and 19F can be observed in the 1H EFNMR spectrum of fluorobenzene (C6H5F).
Heteronuclear J-coupling between 1H and 19F observed using 1H Earth?s field NMR of a fluorobenzene sample. The splitting of the spectral peak is 6Hz. This is the J-coupling constant for this interaction.
3D MRI in the Earth's field
A 3D mandarin image showing cross sections (32 x 32 x 32 pixels) imaging time: 4hours. Field of view (110 mm)3
Track Changes in BE using 1H EFNMR
It is widely known that the Earth?s magnetic field undergoes secular variations on a historical time scale. However, what is less well known is that there exist diurnal, or daily, fluctuations in the Earth?s field that can occur on a time scale of minutes or even seconds. The frequency of an EFNMR signal is highly sensitive to any variations in the magnitude of the Earth?s field and therefore it can be used to track these diurnal changes.
The frequency resolution of the EFNMR spectrum is limited by the signal acquisition time. A typical Terranova experiment will have a frequency resolution of 0.33Hz (8nT). This limited resolution can be greatly improved by considering the phase of the signal. A delay introduced between the signal excitation and detection allows the spins to evolve and acquire a phase offset directly proportional to the magnitude of the Earth?s field. Any fluctuations in the Earth?s field can then be calculated from the phase differences between spectra. Using this method a resolution as precise as 0.006Hz (0.15nT) can be achieved. This is a 50-fold improvement over the frequency-based calculation.
(a) Changes in BE measured from frequency
(b) Changes in BE measured from phase
Variations in the magnitude of the Earth?s magnetic field, BE, over a time period of 42 hours in Wellington, New Zealand as calculated from (a) the frequency and (b) the phase of a time series of 1H EFNMR experiments.
