TY - JOUR

T1 - Imaging obstructed ventilation with NMR using inert fluorinated gases

AU - Kuethe, Dean O.

AU - Caprihan, Arvind

AU - Gach, H. Michael

AU - Lowe, Irving J.

AU - Fukushima, Eiichi

PY - 2000

Y1 - 2000

N2 - We partially obstructed the left bronchi of rats and imaged an inert insoluble gas, SF6, in the lungs with NMR using a technique that clearly differentiates obstructed and normal ventilation. When the inhaled fraction of O2 is high, SF6 concentrates dramatically in regions of the lung with low ventilation-to-perfusion ratios (V̇A/Q̇); therefore, these regions are brighter in an image than where V̇A/Q̇ values are normal or high. A second image, made when the inhaled fraction of O2 is low, serves as a reference because the SF6 fraction is nearly uniform, regardless of V̇/Q̇. The quotient of the first and second images displays the low-V̇A/Q̇ regions and is corrected for other causes of brightness variation. The technique may provide sufficient quantification of V̇A/Q̇ to be a useful research tool. The noise in the quotient image is described by the probability density function for the quotient of two normal random variables. When the signal-to- noise ratio of the denominator image is > 10, the signal-to-noise ratio of the quotient image is similar to that of the parent images and decreases with pixel value.

AB - We partially obstructed the left bronchi of rats and imaged an inert insoluble gas, SF6, in the lungs with NMR using a technique that clearly differentiates obstructed and normal ventilation. When the inhaled fraction of O2 is high, SF6 concentrates dramatically in regions of the lung with low ventilation-to-perfusion ratios (V̇A/Q̇); therefore, these regions are brighter in an image than where V̇A/Q̇ values are normal or high. A second image, made when the inhaled fraction of O2 is low, serves as a reference because the SF6 fraction is nearly uniform, regardless of V̇/Q̇. The quotient of the first and second images displays the low-V̇A/Q̇ regions and is corrected for other causes of brightness variation. The technique may provide sufficient quantification of V̇A/Q̇ to be a useful research tool. The noise in the quotient image is described by the probability density function for the quotient of two normal random variables. When the signal-to- noise ratio of the denominator image is > 10, the signal-to-noise ratio of the quotient image is similar to that of the parent images and decreases with pixel value.

KW - Lung

KW - Magnetic resonance imaging

KW - Nuclear magnetic resonance

KW - Perfusion

KW - Probability density function

KW - Quotient

KW - Sulfur hexafluoride

UR - http://www.scopus.com/inward/record.url?scp=0033923180&partnerID=8YFLogxK

U2 - 10.1152/jappl.2000.88.6.2279

DO - 10.1152/jappl.2000.88.6.2279

M3 - Article

C2 - 10846046

AN - SCOPUS:0033923180

SN - 0161-7567

VL - 88

SP - 2279

EP - 2286

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

IS - 6

ER -