Evaluation of the ventilation-perfusion ratio in lung diseases by simultaneous anterior and posterior image acquisition

Abstract

Ventilation and perfusion images were acquired during tidal breathing using 81mKr gas and 99mTc-MAA. Anterior and posterior functional images of V/Q and Q/V were simultaneously acquired in 34 subjects with various lung diseases and 6 healthy controls. Superimposed anterior and posterior images were constructed and histograms of the frequency distribution for ventilation, perfusion, and the V/Q ratio were displayed for both lungs as well as for the left and right lungs individually. Blood gas analysis and general lung function tests were also performed on the day before scintigraphy. A correlation between marked uneven distribution of V/Q and A-aDO2 was found. When the proportion of counts at V/Q < 0.67 and/or V/Q > 1.50 in the V/Q counts histogram was compared with A-aDO2, there was a significant positive correlation for anterior images (r = 0.684, p < 0.05), posterior images (r = 0.654, p < 0.05) and superimposed images (r = 0.696, p < 0.05). Superimposed images therefore showed the highest correlation. There was no correlation between the results of lung function testing and A-aDO2. Coronal SPECT images were also obtained in 15 patients and compared with the superimposed anterior and posterior planar images. There was a good correlation (r = 0.888, p < 0.001) between both the imaging methods regarding the marked uneven distribution of V/Q. Simultaneous anterior and posterior planar image acquisition reduces the examining time, is simple, and is noninvasive. The present results also suggest that it is useful for quantitative evaluation of the ventilation-perfusion ratio.

Distribution of ventilation‐to‐perfusion ratios analysed in planar scintigrams of emphysematous patients

“…4) is consistent with the findings from multiple inert gas elimination studies ( Wagner et al ., 1977 ). Furthermore, the normal range of V/Q established in this study is in good agreement with the normal range established using 81m Kr ( Nakata et al ., 1994 ).…”

“…Unlike previous quantitative methods in pulmonary scintigraphy, which are based on ‘stripe regions’ ( Burton et al ., 1984 ; Xu et al ., 1998 ) or pixels ( Ishii et al ., 1978 ; Nakata et al ., 1994 ), we divided the lungs into 2·03 × 2·03 cm square regions. The square regions are closer to the shape of radioactivity defects in emphysematous patients than stripe regions.…”

“…Ventilation‐to‐perfusion relationship analyses using radionuclide imaging techniques have often been based on visual interpretation ( Quaife & Kass, 1972; Van Beek et al ., 1994 ; Trujillo et al ., 1997 ). The few attempts that have been made to quantify regional ventilation‐to‐perfusion ratios were based on pulmonary scintigraphy using radioactive gases ( Ishii et al ., 1978 ; Burton et al ., 1984 ; Nakata et al ., 1994 ). At present, 99m Tc‐Technegas (Tetley Manufacturing Ltd, Sydney, Australia) has become widespread in clinical practice, yet there are no regional ventilation‐to‐perfusion ratio quantification methods available using 99m Tc‐Technegas.…”

Long-term follow-up of patients with high-risk congenital diaphragmatic hernia

“…Muratore et al [11], reported that only 16% of survivors of high-risk CDH treated with ECMO had a V/Q mismatch of more than 10%, which seems surprisingly low. Although no investigation has been performed concerning clinical effects of V/Q mismatch in CDH survivors, it has been reported that V/Q mismatch of more than 50% is related to hypoxemia in patients with pulmonary embolism and lung cancer [18]. Actually, hypoxemia seems to be caused by a reduction of ventilation in the contralateral lung as a shunt effect.…”

Which is Better - A Standalone Ventilation or Perfusion Scan or Combined Imaging to Predict Postoperative FEV1in One Seconds in Patients Posted for Lung Surgeries with Borderline Pulmonary Reserve

“…Based on the patterns of V and Q findings as per Nakata et al .,[ 7 ] 4 types of distribution was observed.…”