Dynamic perfusion digital radiography for predicting pulmonary function after lung cancer resection

Abstract

Background: Accurate prediction of postoperative pulmonary function is important for ensuring the safety of patients undergoing radical resection for lung cancer. Dynamic perfusion digital radiography is an excellent and easy imaging method for detecting blood flow in the lung compared with the less-convenient conventional lung perfusion scintigraphy. As such, the present study aimed to confirm whether dynamic perfusion digital radiography can be evaluated in comparison with pulmonary perfusion scintigraphy in predicting early postoperative pulmonary function and complications.

Methods: Dynamic perfusion digital radiography and spirometry were performed before and 1 and 3 months after radical resection for lung cancer. Correlation coefficients between blood flow ratios calculated using dynamic perfusion digital radiography and pulmonary perfusion scintigraphy were then confirmed in the same cases. In all patients who underwent dynamic perfusion digital radiography, the correlation predicted values calculated from the blood flow ratio, and measured values were examined. Furthermore, ppo%FEV1 or ppo%DLco values, which indicated the risk for perioperative complications, were examined.

Results: A total of 52 participants who satisfied the inclusion criteria were analyzed. Blood flow ratios measured using pulmonary perfusion scintigraphy and dynamic perfusion digital radiography showed excellent correlation and acceptable predictive accuracy. Correlation coefficients between predicted FEV1 values obtained from dynamic perfusion digital radiography or pulmonary perfusion scintigraphy and actual measured values were similar. All patients who underwent dynamic perfusion digital radiography showed excellent correlation between predicted values and those measured using spirometry. A significant difference in ppo%DLco was observed for respiratory complications but not cardiovascular complications.

Conclusions: Our study demonstrated that dynamic perfusion digital radiography can be a suitable alternative to pulmonary perfusion scintigraphy given its ability for predicting postoperative values and the risk for postoperative respiratory complications. Furthermore, it seemed to be an excellent modality because of its advantages, such as simplicity, low cost, and ease in obtaining in-depth respiratory functional information.

Trial registration: Registered at UMIN on October 25, 2017. https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_his_list.cgi?recptno=R000033957 Registration number: UMIN000029716.

Keywords: Dynamic chest radiography; Dynamic perfusion digital radiography; Prediction of postoperative respiratory function; Pulmonary perfusion; Pulmonary perfusion scintigraphy.

Fig. 1

Flow diagram of the study population. Exclusion criteria: diseases other than lung cancer (n = 2), wedge resection of the lung (n = 1), lost to follow-up (n = 1), and refused informed consent before postoperative (n = 1)

Fig. 2

Pulmonary perfusion imaging. Pulmonary perfusion (red line) was evaluated by visualizing the degree of waveform correlation value between pixel value changes in the lung regions (green line) and periodic pixel value changes corresponding to the cardiac cycle (blue line) under cross-correlation calculation processing. Cross-correlation value changes are displayed in shades of red on each frame of the chest dynamic image

Fig. 3

Comparison between blood flow ratio (BFR) from dynamic perfusion digital radiography and pulmonary perfusion scintigraphy. a Correlation between the BFR on the affected side obtained from dynamic perfusion digital radiography (DPDR) and pulmonary perfusion scintigraphy (PPS). b Bland–Altman analysis between affected side BFR obtained from DPDR and PPS. The black line indicates the mean, the dotted lines indicate the limit of agreement, and the broken lines indicate mean ± 2SD

Fig. 4

Comparison between postoperative predicted and measured values of FEV1 and DLco. Correlations between actual postoperatively measured values and those predicted using dynamic perfusion digital radiography (DPDR) for the forced expiratory volume in 1 s (FEV1) and diffusing capacity for carbon monoxide (DLco) at postoperative months 1 (a, c) and 3 (b, d)

Fig. 5

Relationship between perioperative complications and postoperative predictive value. Differences between predicted postoperative % forced expiratory volume in 1 s (ppo%FEV1) and predicted postoperative % diffusing capacity for carbon monoxide (ppo%DLco) for the prediction of perioperative respiratory complications