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Magnetic Resonance Imaging Quantification of Pulmonary Perfusion using Calibrated Arterial Spin Labeling
Published on: May 30, 2011
Spin-label oximetry at Q- and W-band
W K Subczynski1, L Mainali, T G Camenisch
1Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA.
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|February 1, 2011
Summary
Spin-lattice relaxation times (T₁s) generally peak at Q-band (35 GHz) for spin-labels in membranes. This frequency is optimal for measuring oxygen
Area of Science:
- Electron Paramagnetic Resonance (EPR) Spectroscopy
- Biophysics
- Membrane Biophysics
Background:
- Spin-lattice relaxation times (T₁s) of spin-labels vary with microwave frequency.
- Previous studies indicated increasing T₁s with frequency up to 35 GHz.
- Water-soluble spin-labels showed shorter T₁s at 94 GHz compared to 35 GHz.
Purpose of the Study:
- To investigate the frequency dependence of T₁s for lipid-type spin-labels in membranes at higher microwave frequencies (Q- and W-band).
- To confirm decreasing T₁ trends at W-band (94 GHz) for lipid-type spin-labels.
- To evaluate the utility of saturation-recovery (SR) EPR for oxygen transport parameter measurements.
Main Methods:
- Electron Paramagnetic Resonance (EPR) spectroscopy at X-band, Q-band (35 GHz), and W-band (94 GHz).
- Utilized saturation-recovery (SR) technique to measure spin-lattice relaxation times (T₁s).
- Employed stearic acid (n-SASL) and phosphatidylcholine (n-PC) spin-labels in DMPC and POPC model membranes.
Main Results:
- T₁s for lipid-type spin-labels in membranes decreased at W-band (94 GHz), confirming previous observations.
- The longest T₁ values were generally observed at Q-band (35 GHz).
- The contribution of dissolved oxygen to relaxation rate was independent of microwave frequency up to 94 GHz.
Conclusions:
- Q-band (35 GHz) is generally optimal for achieving the longest spin-lattice relaxation times (T₁s), beneficial for oxygen collision studies.
- SR EPR at Q- and W-band enables precise measurement of the oxygen transport parameter (W).
- SR EPR oximetry at Q- and W-band is a powerful technique for studying small sample volumes (~30 nL).
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Guidelines For Measuring Vital Signs
Following these guidelines can help nurses accurately measure vital signs, assess changes in patient conditions, and provide timely treatment when necessary. Adhering closely to the guidelines ensures the accuracy and reliability of the results.
Before taking a patient's vital signs, a nurse would consider and assess the patient's comfort level and ensure appropriate equipment is available.
Before taking a patient's vital signs, a nurse would consider and assess the patient's comfort level and ensure appropriate equipment is available.
Special considerations while measuring oxygen saturation
Assessing respiratory rate concurrently with pulse measurement is fundamental to patient care, providing valuable insights into the patient's respiratory function. The normal breathing rate for an adult usually falls within a normal range of 12 to 20 breaths per minute. Abnormal respiratory rates can signal underlying health conditions or the need for immediate intervention.
Ensuring accuracy in vital sign recordings while prioritizing patient comfort and minimizing anxiety is important.
Ensuring accuracy in vital sign recordings while prioritizing patient comfort and minimizing anxiety is important.

