On the oxygenation‐dependent 129Xe T 1 in blood

Abstract

The spin-lattice relaxation time, T 1 , of hyperpolarized 129 Xe in blood is sensitive to blood oxygenation. In particular, it has been shown that 129 Xe T 1 is shorter in venous blood than in arterial blood. We have studied the T 1 of hyperpolarized 129 Xe dissolved in human blood as a function of blood oxygenation level, sO 2 , in the physiological oxygenation range. We show that the 129 Xe relaxation rate, T À1 1 ,varies in a nonlinear fashion as a function of sO 2 . This finding suggests that direct interaction of xenon with the paramagnetic heme group of deoxyhemoglobin is not the dominant oxygenation-dependent relaxation mechanism for 129 Xe in blood. These results corroborate the idea that the oxygenation-dependence of 129 Xe T 1 is determined by conformational changes of hemoglobin induced by oxygen binding.

Relaxation and exchange dynamics of hyperpolarized 129 Xe in human blood

“…As first demonstrated by Pauling and Coryell (27), the fully deoxygenated form of hemoglobin-deoxyhemoglobin, Hb 4 (electron spin S 5 2)-is paramagnetic, whereas the fully oxygenated form-oxyhemoglobin, Hb 4 deoxygenated and fully oxygenated state vary approximately linearly with blood oxygenation. The observed nonlinear decrease in the 129 Xe relaxation rate with increasing blood oxygenation (decreased net paramagnetism of the hemoglobin molecules) agrees with the findings of Wolber et al (10), in which a nonlinear relationship between the 129 Xe relaxation rate and blood oxygenation was also observed with the same direction of trend albeit over a smaller oxygenation range.…”

“…While the 129 Xe peak in plasma, located 196 ppm downfield from the 129 Xe gas reference at 0 ppm, was found to be fixed in center frequency over the full range of blood oxygenation values, the 129 Xe‐RBC chemical shift increased from 220 ppm in approximately fully deoxygenated blood ( s O 2 = 0.06) to 224 ppm in completely oxygenated blood ( s O 2 = 1.00). This shift has been observed previously and can be explained by a decrease in 129 Xe chemical shift shielding constant with increasing blood oxygenation .…”

Relaxation and exchange dynamics of hyperpolarized 129 Xe in human blood

“…As first demonstrated by Pauling and Coryell (27), the fully deoxygenated form of hemoglobin-deoxyhemoglobin, Hb 4 (electron spin S 5 2)-is paramagnetic, whereas the fully oxygenated form-oxyhemoglobin, Hb 4 deoxygenated and fully oxygenated state vary approximately linearly with blood oxygenation. The observed nonlinear decrease in the 129 Xe relaxation rate with increasing blood oxygenation (decreased net paramagnetism of the hemoglobin molecules) agrees with the findings of Wolber et al (10), in which a nonlinear relationship between the 129 Xe relaxation rate and blood oxygenation was also observed with the same direction of trend albeit over a smaller oxygenation range.…”

“…While the 129 Xe peak in plasma, located 196 ppm downfield from the 129 Xe gas reference at 0 ppm, was found to be fixed in center frequency over the full range of blood oxygenation values, the 129 Xe‐RBC chemical shift increased from 220 ppm in approximately fully deoxygenated blood ( s O 2 = 0.06) to 224 ppm in completely oxygenated blood ( s O 2 = 1.00). This shift has been observed previously and can be explained by a decrease in 129 Xe chemical shift shielding constant with increasing blood oxygenation .…”

In vivo hyperpolarized 129Xe NMR spectroscopy in tumors

“…A more efficient wash‐out of the emulsion would be expected in the more vascular GH‐3. Moreover, 129 Xe T 1 in blood is shorter than in other tissues and in the emulsion, a result of xenon interaction with hemoglobin (8). 129 Xe T 1 s of 3 s and 6 s were measured in deoxygenated and oxygenated human blood, respectively (7).…”

Measurement of alveolar oxygen partial pressure in the rat lung using Carr‐Purcell‐Meiboom‐Gill spin–spin relaxation times of hyperpolarized 3 He and 129 Xe at 74 mT

“…It is therefore hypothesized that this variation of 129 Xe R 2,CPMG is the result of the interaction of 129 Xe dissolved in blood of varying oxygenation levels. Previous studies measuring R 1 of 129 Xe dissolved in blood in vitro as a function of oxygenation (36,37) have shown an increase in R 1 with decreasing blood oxygenation hypothesized to be due to the increase in deoxyhemoglobin. There are also examples in the literature of 129 Xe R 2 measured in vitro in both oxygenated and deoxygenated blood.…”

Relaxation and exchange dynamics of hyperpolarized 129 Xe in human blood

“…As first demonstrated by Pauling and Coryell (27), the fully deoxygenated form of hemoglobin-deoxyhemoglobin, Hb 4 (electron spin S 5 2)-is paramagnetic, whereas the fully oxygenated form-oxyhemoglobin, Hb 4 deoxygenated and fully oxygenated state vary approximately linearly with blood oxygenation. The observed nonlinear decrease in the 129 Xe relaxation rate with increasing blood oxygenation (decreased net paramagnetism of the hemoglobin molecules) agrees with the findings of Wolber et al (10), in which a nonlinear relationship between the 129 Xe relaxation rate and blood oxygenation was also observed with the same direction of trend albeit over a smaller oxygenation range.…”

“…While the 129 Xe peak in plasma, located 196 ppm downfield from the 129 Xe gas reference at 0 ppm, was found to be fixed in center frequency over the full range of blood oxygenation values, the 129 Xe‐RBC chemical shift increased from 220 ppm in approximately fully deoxygenated blood ( s O 2 = 0.06) to 224 ppm in completely oxygenated blood ( s O 2 = 1.00). This shift has been observed previously and can be explained by a decrease in 129 Xe chemical shift shielding constant with increasing blood oxygenation .…”

In vivo hyperpolarized 129Xe NMR spectroscopy in tumors

“…A more efficient wash‐out of the emulsion would be expected in the more vascular GH‐3. Moreover, 129 Xe T 1 in blood is shorter than in other tissues and in the emulsion, a result of xenon interaction with hemoglobin (8). 129 Xe T 1 s of 3 s and 6 s were measured in deoxygenated and oxygenated human blood, respectively (7).…”

Measurement of alveolar oxygen partial pressure in the rat lung using Carr‐Purcell‐Meiboom‐Gill spin–spin relaxation times of hyperpolarized 3 He and 129 Xe at 74 mT

“…It is therefore hypothesized that this variation of 129 Xe R 2,CPMG is the result of the interaction of 129 Xe dissolved in blood of varying oxygenation levels. Previous studies measuring R 1 of 129 Xe dissolved in blood in vitro as a function of oxygenation (36,37) have shown an increase in R 1 with decreasing blood oxygenation hypothesized to be due to the increase in deoxyhemoglobin. There are also examples in the literature of 129 Xe R 2 measured in vitro in both oxygenated and deoxygenated blood.…”

Relaxation and exchange dynamics of hyperpolarized 129 Xe in human blood

“…As first demonstrated by Pauling and Coryell (27), the fully deoxygenated form of hemoglobin-deoxyhemoglobin, Hb 4 (electron spin S 5 2)-is paramagnetic, whereas the fully oxygenated form-oxyhemoglobin, Hb 4 deoxygenated and fully oxygenated state vary approximately linearly with blood oxygenation. The observed nonlinear decrease in the 129 Xe relaxation rate with increasing blood oxygenation (decreased net paramagnetism of the hemoglobin molecules) agrees with the findings of Wolber et al (10), in which a nonlinear relationship between the 129 Xe relaxation rate and blood oxygenation was also observed with the same direction of trend albeit over a smaller oxygenation range.…”

“…While the 129 Xe peak in plasma, located 196 ppm downfield from the 129 Xe gas reference at 0 ppm, was found to be fixed in center frequency over the full range of blood oxygenation values, the 129 Xe‐RBC chemical shift increased from 220 ppm in approximately fully deoxygenated blood ( s O 2 = 0.06) to 224 ppm in completely oxygenated blood ( s O 2 = 1.00). This shift has been observed previously and can be explained by a decrease in 129 Xe chemical shift shielding constant with increasing blood oxygenation .…”

In vivo hyperpolarized 129Xe NMR spectroscopy in tumors

“…A more efficient wash‐out of the emulsion would be expected in the more vascular GH‐3. Moreover, 129 Xe T 1 in blood is shorter than in other tissues and in the emulsion, a result of xenon interaction with hemoglobin (8). 129 Xe T 1 s of 3 s and 6 s were measured in deoxygenated and oxygenated human blood, respectively (7).…”

Measurement of alveolar oxygen partial pressure in the rat lung using Carr‐Purcell‐Meiboom‐Gill spin–spin relaxation times of hyperpolarized 3 He and 129 Xe at 74 mT

“…It is therefore hypothesized that this variation of 129 Xe R 2,CPMG is the result of the interaction of 129 Xe dissolved in blood of varying oxygenation levels. Previous studies measuring R 1 of 129 Xe dissolved in blood in vitro as a function of oxygenation (36,37) have shown an increase in R 1 with decreasing blood oxygenation hypothesized to be due to the increase in deoxyhemoglobin. There are also examples in the literature of 129 Xe R 2 measured in vitro in both oxygenated and deoxygenated blood.…”