The MQC+ is a low-field NMR (Nuclear Magnetic Resonance) analyzer, which measures relaxation times (T1 and T2) for various materials, including MRI contrast agents.

Steps for Analysis:

1. Sample Preparation:

Dilute the contrast agent (e.g., gadolinium-based for T1 or iron oxide-based for T2) to desired concentrations in an appropriate solvent.

Place the prepared sample in the NMR tube or container suitable for the MQC+.

2. Calibration:

Perform calibration using a standard sample with known T1 and T2 values.

3. Measurement:

The MQC+ applies a radiofrequency pulse sequence to excite the nuclei in the sample.

For T1 measurement, an inversion recovery or saturation recovery sequence is used.

For T2 measurement, a spin-echo sequence or Carr-Purcell-Meiboom-Gill (CPMG) sequence is used.

4. Data Analysis:

The relaxation times are calculated from the decay curves of the NMR signal.

T1 decay is exponential, while T2 decay involves coherence loss of the spin system.

5. Interpretation:

Shorter T1 times indicate efficient T1 contrast agents, typically used for bright imaging of tissues like liver or blood vessels.

Shorter T2 times indicate efficient T2 agents, often used for detecting abnormalities like tumors or hemorrhages.

Your image shows you used a CPMG sequence which gives you T2 measurements. You fitted the data to 2 exponential model which give you an Intensity (T=0) point and time constant (fitted TC which is T2) and a weighted factor (75% and 25%). This is what you use in your relaxivity models.