PMC

Chemical structures of the two PARACEST agents examined in this study.

Pulse sequence. The sequence is a standard 2D, multislice, gradient-echo sequence with a CEST saturation pulse inserted before each observation pulse.

An Omega plot derived from images collected using a 1.5T clinical scanner on phantom samples containing either 20 mM (●) or 60 mM (■) Eu (DOTA-(gly)₄) ⁻ dissolved in water at pH 7. The lines represent the linear least square fittings of the data.

a) High resolution ¹H NMR spectra of EuDOTA-(gly-OEt)₄³⁺ in water at pH 7 (showing only the downfield region). The ¹H resonance near 57 ppm is the Eu³⁺- bound water molecule. b) Calculated Eu³⁺-bound water resonance at each temperature based upon line-fitting of the bound and bulk water resonances at each temperature. The bound water lifetimes at each temperature are shown.

a) CEST spectra of 20 mM EuDOTA(gly)₄ ⁻ in water at pH 7, 9.4 T collected 25ºC with varying B₁ = 487, 606, 689, 833, 952, 1212 Hz with a presaturation time of 10 s. b) An Omega plot − M_z /(100 − M_z) vs 1/B₁² for 20 mM Eu(DOTA-(gly)₄) ⁻ in water at pH 7 at 25°C using a 10 s saturation pulse at the indicated power levels.

a) CEST spectra of 20 mM EuDOTA(gly-OEt)₄ ³⁺ in water at pH 7, 9.4 T collected at temperatures of (■) 38ºC, (▲) 25ºC, (●) 15ºC, (□) 10ºC, and (○) 4ºC using a fixed B₁ = 162 Hz and a presaturation time of 3 s. b) An Omega plot - M_z /(100 − M_z) vs 1/B₁² – for 5 mM (▲), 10 mM (■) and 20 mM (●) Eu(DOTA-(glyOEt)₄)³⁺ in water at pH 7 at 25°C using a 10 s saturation pulse at the indicated power levels.