document: Ventilation-perfusion ratio of signal intensity in human lung using oxygen-enhanced and arterial spin labeling techniques This study investigates the distribution of ventilation-perfusion -LRB- V/Q -RRB- signal intensity -LRB- SI -RRB- ratios using oxygen-enhanced and arterial spin labeling -LRB- ASL -RRB- techniques in the lungs of 10 healthy volunteers . Ventilation and perfusion images were simultaneously acquired using the flow-sensitive alternating inversion recovery -LRB- FAIR -RRB- method as volunteers alternately inhaled room air and 100 % oxygen . Images of the T/sub 1 / distribution were calculated for five volunteers for both selective -LRB- T/sub 1f / -RRB- and nonselective -LRB- T/sub 1 / -RRB- inversion . The average T/sub 1 / was 1360 ms + or-116 ms , and the average T/sub 1f / was 1012 ms + or-112 ms , yielding a difference that is statistically significant -LRB- P < 0.002 -RRB- . Excluding large pulmonary vessels , the average V/Q SI ratios were 0.355 + or-0 .073 for the left lung and 0.371 + or-0 .093 for the right lung , which are in agreement with the theoretical V/Q SI ratio . Plots of the WO SI ratio are similar to the logarithmic normal distribution obtained by multiple inert gas elimination techniques , with a range of ratios matching ventilation and perfusion . This MRI V/Q technique is completely noninvasive and does not involve ionized radiation . A limitation of this method is the nonsimultaneous acquisition of perfusion and ventilation data , with oxygen administered only for the ventilation data
doc_bio_tags: O O O B I O B I O O O B I I I O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O B I I I O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O
extractive_keyphrases: human lung signal intensity arterial spin labeling techniques perfusion images logarithmic normal distribution nonsimultaneous acquisition mri multiple inert gas elimination
abstractive_keyphrases: ventilation-perfusion ratio oxygen-enhanced techniques ventilation images flow-sensitive alternating inversion recovery gas exchange efficiency pathomechanisms time delay pixel-by-pixel maps pulmonary embolism chronic obstructive pulmonary disease