Statistical analysis
Continuous variables were described as the mean + SD for normally
distributed data and median (25% to 75% quartile) for non-normally
distributed data, and comparisons between groups were performed with
Student t test. Categorical variables were described as counts and
compared by chi-square analysis. Using the pulmonary venography as the
gold standard, the sensitivity, specificity, positive predictive value
(PPV), and negative predictive value (NPV) were calculated including the
95 % confidence interval (CI) based on a binomial distribution. The
receiver operating characteristic (ROC) curve was delineated and area
under curve (AUC) was calculated to determine the diagnostic ability of
both tools. Spearman correlation was conducted to investigate the
relationship between occlusion degree and corresponding cryoablation
parameters.
All tests were 2-tailed, and a statistical significance was established
at P < 0.05. All analyses were performed using SPSS software
(version 22.0; SPSS, Inc., Chicago).