Quantitative MRI parameters include measures of 1) tissue hydration –the proton densities (PD) of the mobile and the semisolid water pools--, 2) tissue micro- and macro-kinetics (diffusion coefficient, perfusion parameters, and flow velocity), and 3) measures of spin interactions with the microscopic magnetic milieu via the relaxation times (T1, T2, T2*). Of these qMRI parameters, only the relaxation times depend on the main magnetic field strength B0 and the others are purely determined by the physical and physiological state of tissue. Accordingly, PD as well as the diffusion coefficient, as measured by the Stejskal-Tanner pulsed-field-gradient (PFG) experiment (1), are theoretically and experimentally independent of B0. Correlation time diffusion is an alternative qMRI technique for mapping the diffusion coefficient (2-4) --termed DCT to distinguish it from DPFG-- that uses relaxometric (T1 and T2) and proton density (PD) information (5-10). Hence, although DCT is theoretically B0 independent, the question arises as to whether the field independence holds in practice. To help elucidate this question, a volunteer was scanned at 1.5T and 3.0T with the same multispectral qMRI technique using the quadra-FSE pulse sequence and with the standard PFG diffusion technique.The volunteer (male 35yo) was scanned at 3.0T (Discovery MR750, GE Healthcare, Waukesha, WI) and a week later at 1.5T (Optima MR450w, GE Healthcare, Waukesha, WI). The imaging protocol included: a) standard PFG diffusion-weighted scan using the DW single-shot EPI sequence, and b) a newly developed pulse sequence termed herein quadra fast spin-echo (quadra-FSE; see Figure 1), which is multispectral in PD, T1, and T2 and therefore can be used for DCT mapping. The DW-SE-sshEPI sequence was implemented with TE=63.9ms and TR=8,000ms) and diffusion encoding along the three physical axes (b=0 and 1,000s/mm2). The quadra-FSE pulse sequence is a concatenation of two dual-echo fast spin-echo (DE-FSE) that are run consecutively with equal parameters including pre-scan values, but with different TR values and consequently different levels of T1 saturation. The key pulse sequence parameters are the two TRs (5,320 & 600ms) and the two effective echo times (TE1eff=22.1 & TE2eff=99.6ms with ETL=10). Four directly acquired images per slice are generated with varying levels of T1- and T2-weighting; specifically Sat1_E1, Sat1_E2, Sat2_E1, and Sat2_E2 (see Figure 1) and these images can be qMRI processed to generate coregistered maps of PD, T1, and T2. In turn, these maps were used to map DCT using equations derived from the microscopic theory of relaxation. The directly acquired images of both scans were transferred to a personal computer equipped with Mathcad (version 2001i, PTC, Needham, MA) and qMRI processed with model conforming algorithms to produce maps of PD, T1, T2, DCT, and DPFG. These maps were segmented with a dual-clustering algorithm leading to datasets representing the totality of the intracranial tissues (white matter (WM), gray matter (GM), meninges, and cerebrospinal fluid (CSF)). The resulting intracranial matter (ICM) segments were further processed with a pixel counting algorithm to generate histograms representing the individual distributions of each qMRI parameter. ICM T1 histograms representing all-intracranial tissues of the same volunteer scanned at 1.5T (blue line) and 3.0T (red line) with the quadra-FSE pulse sequence are shown in Figure 2. These are fundamentally tri-modal histograms with well-defined spectral features representing WM, GM, and CSF. Note that as is well known, the WM and GM T1values at 3.0T are longer than at 1.5T by 15%-20%. Analogously, T2 histograms of the all-intracranial tissues of the same volunteer scanned at 1.5T (blue line) and 3.0T (red line) with the quadra-FSE pulse sequence are shown in Figure 3. In this case the spectral shift is in the opposite direction; the T2 values at 3.0T are shorter than at 1.5T by 15%-20%. Despite the B0 dependent shifts of the relaxation time histograms, the PD, DCT, and DPFG histograms do not exhibited significant B0 shifts (see Figures 4 & 5).These experiments performed on the same human subject confirm the hypothesis that the physico-physiological qMRI parameters (PD, DCT, and DPFG) are independent of the main magnetic field strength, within experimental uncertainty. Most importantly, this study further confirms the physical interpretation of DCT as a purely physical and B0-independent diffusion measure, despite the fact that it is calculated using the relaxation times, which are B0 dependent.