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. 2014 May 13;53(16):8311–8321. doi: 10.1021/ic5006083

Table 5. T1 Relaxivitiy, T2 Relaxivitiy, and CEST Contrast of Complexes in Different Media at 4.7 T.

      buffer   rabbit serum agarose
complex Δωa T1 relaxivityb T2 relaxivityc CESTd CESTe CESTf
  (ppm) (mM·s–1) (mM·s–1) (%) (%) (%)
[Ni(L)]2+ 72 0.012g,h 0.092g,h 11 ± 0.3 0 4.6 ± 1.6
[Co(L)]2+ 59 0.038g,h 0.119g,h 9.1 ± 2.7 5.4 ± 0.6 6.7 ± 0.5
[Fe(L)]2+ 92 0.097 0.203 5.6 ± 1.4 2.5 ± 1.1 5.4 ± 0.2
a

The chemical shift of the furthest downfield shifted amide (NH) exchangeable proton versus the water proton resonance.

b

T1 relaxivity for 0.25–8 mM paraCEST agent, 100 mM NaCl, 20 mM HEPES, pH 7.3–7.4.

c

T2 relaxivity for 0.25–8 mM paraCEST agent, 100 mM NaCl, 20 mM HEPES, pH 7.3–7.4.

d

% CEST of 4 mM paraCEST agent, 100 mM NaCl, 20 mM HEPES pH 7.3–7.4.

e

% CEST of 4 mM paraCEST agent rabbit serum pH 7.3–7.5.

f

% CEST of 4 mM paraCEST agent in 20 mM HEPES pH 7.3–7.4, 100 mM NaCl in 4% agarose gel (w/w). CEST images were acquired on a 4.7 T MRI scanner with B1 = 12 μT at 37 °C.

g,h

Measurements g and h are referenced from previous work.7,10