RESUMO
Objective To stratify the risks of patients with acute pulmonary embolism (APE) and pulmonary hypertension (PH) by dynamic pulmonary perfusion imaging (DPPI) and pulmonary perfusion imaging (PPI). Methods From October 2007 to February 2009, 20 healthy volunteers ( 12 males, 8 females; mean age =48.47 ±13.47 years) and 31 APE patients (21 males, 10 females; mean age =47.68 ±18.06 years; from October 2007 to July 2009) were included in the study. DPPI and PPI were performed in all subjects. Percentage of perfusion defect scores ( PPDs% ) were calculated by semi-quantitative analysis of PPI. Risk levels were defined according to PPDs% calculated from PPI: normal (PPDs% =0); very low risk (0 ＜ PPDs% ≤10% ); low risk (10% ＜ PPDs% ≤20% ); moderate risk (20% ＜ PPDs% ≤40% );high risk (40% ＜ PPDs% ≤60% ) and very high risk ( PPDs% ＞ 60% ). Lung equilibrium time (LET)was calculated on region of interest (ROI) drawn over DPPI. Clinical risk was scored by Aujesky method.The t-test, ANOVA and correlation analysis were used with SPSS 13.0 software. Results ( 1 ) LET in healthy volunteers and APE patients was ( 12.18 ± 3.28) and (32.90 ± 14.29) s respectively (t = 6. 81,P ＜ 0. 01 ). (2) The correlation coefficient, coefficient of determination between LET and PPDs% in APE patients were 0.93 and 0. 87, respectively. The correlation coefficient between LET and clinical risk score was 0.86. (3)The mean LET of APE patients in very low risk (n =5), low risk (n = 12), moderate risk (n=9), high risk (n=4) and very high risk groups (n=1) were (19.59 ±0.04), (25.03 ±0.08),(36.07 ±0. 10), (57.15 ±0.06) and (70 ±0.00) s, respectively. There was significant difference among APE patients with different risk levels (F =16. 78, P ＜0.01). Conclusions ( 1 ) DPPI was a reliable, convenient and non-invasive method for the evaluation of PH in APE. (2) Combined LET of DPPI and PPDs% of PPI was valuable for risk stratification and prognosis estimation in APE patients.