Abstract:
PURPOSE:To investigate the feasibility of estimating calibration constants (K and T2o ) in vivo for converting whole-blood T2 to blood hemoglobin oxygen saturation (HbO2 ) according to the Luz-Meiboom model, 1/T2=1/T2o+K(1-HbO2)2, where K and T2o are relaxivity and transverse relaxation time of fully saturated blood, respectively. METHODS:A range of HbO2 values was achieved in the superficial femoral vein with intermittent cuff occlusion in seven healthy adults (four males) to establish a calibration curve between blood T2 and HbO2 at 1.5T. HbO2 was derived via MR susceptometry, a technique previously validated, and the transverse relaxation time was quantified with an optimized T2 -prepared balanced steady-state free precession pulse sequence. To evaluate the accuracy of the in vivo calibration method, T2 and HbO2 were quantified in the superior sagittal sinus in six additional subjects and compared with susceptometry. RESULTS:Two sets of gender-specific calibration constants were derived, one for each gender corresponding to hematocrits of 0.47 ± 0.02 for males and 0.38 ± 0.01 for females, yielding K/T2o = 41 Hz/260 ms and 26 Hz/280 ms, respectively. The in vivo calibration returned physiologically plausible superior sagittal sinus SvO2 values (65 ± 5% HbO2 ), and there was no significant difference between the results from the two methods (average difference -0.3% HbO2 ). CONCLUSION:The results show feasibility of performing in vivo calibration for converting whole-blood T2 to HbO2 . The proposed approach bypasses the involved and cumbersome processes associated with in vitro calibration. Magn Reson Med 79:2290-2296, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Langham MC,Rodríguez-Soto AE,Schwartz N,Wehrli FWdoi
10.1002/mrm.26885subject
Has Abstractpub_date
2018-04-01 00:00:00pages
2290-2296issue
4eissn
0740-3194issn
1522-2594journal_volume
79pub_type
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