Comparison of dynamic flat‐panel detector‐based chest radiography with nuclear medicine ventilation‐perfusion imaging for the evaluation of pulmonary function: A clinical validation study

Abstract

Purpose: Dynamic chest radiography (DCR) is a flat-panel detector (FPD)-based functional lung imaging technique capable of measuring temporal changes in radiographic lung density due to ventilation and perfusion. The aim of this study was to determine the diagnostic performance of DCR in the evaluation of pulmonary function based on changes in radiographic lung density compared to nuclear medicine lung scans. Methods: This study included 53 patients with pulmonary disease who underwent DCR and nuclear medicine imaging at our institution. Dynamic chest radiography was conducted using a dynamic FPD system to obtain sequential chest radiographs during one breathing cycle. The maximum change in the average pixel value (Δ max) was measured, and the percentage ofΔ max in each lung region, calculated relative to the sum of all lung regions (Δ max %), was calculated for each factor (ventilation and perfusion). The Δ max % was compared with the accumulation of radioactive agents (radioactive agents%) on ventilation and perfusion scans in each lung and lung region using correlation coefficients and scatter plots. The ratio of ventilation to perfusion Δ max % was calculated and compared with nuclear medicine ventilation-perfusion (V/Q) findings in terms of sensitivity and specificity for V/Q mismatch in each lung region. Results: There was a high correlation between Δ max % and radioactive agents% for each lung (Ventilation: r = 0.81, perfusion: r = 0.87). However, correlation coefficients were lower (0.37 to 0.80) when comparing individual lung regions, with the upper lung regions showing the lowest correlation coefficients. The sensitivity and specificity of DCR for V/Q mismatch were 63.3% (19/30) and 60.1% (173/288), respectively. Motion artifacts occasionally increased Δ max %, resulting in false negatives. Conclusions: Ventilation and perfusion Δ max % correlated reasonably with radioactive agents% on ventilation and perfusion scans. Although the regional correlations were lower and the detection performance for V/Q mismatch was not enough for clinical use at the moment, these results suggest the potential for DCR to be used as a functional imaging modality that can be performed without the use of radioactive contrast agents. Further technical improvement is required for the implementation of DCR-based V/Q studies.

Dynamic Chest X-Ray Using a Flat-Panel Detector System: Technique and Applications

“…Other types of functional maps can be created using specific images depending on the purpose. In addition, ventilation-perfusion (V/Q) mismatch can be evaluated by combining ventilation and perfusion imaging using DXR ( 2 66 67 68 ). V/Q mismatch is an important diagnostic factor for treatment strategy, and scintigraphy is generally used in the clinical setting ( 69 70 ).…”

Dynamic chest radiography: clinical validation of ventilation and perfusion metrics derived from changes in radiographic lung density compared to nuclear medicine imaging

“…For example, recent animal studies have indicated that changes in radiographic lung density correlated strongly with both blood and inspired air volume, and that functional abnormalities such as limited air flow, trapped air, and pulmonary embolism, could be detected as decreased changes in radiographic lung density, even with no use of radiopharmaceutical and contrast agents (30,31). Moreover, a preliminary clinical study found a high correlation between changes in radiographic lung density and the total accumulation of radioactive agents at the lobar/whole-lung level, and demonstrated the feasibility of DCR-derived ventilation-perfusion studies (32). These findings highlight the ability of DCR to provide ventilation and perfusion metrics on the basis of changes in radiographic lung density.…”

“…Except for the breathing, the setting was the same as for conventional chest radiography; the imaging was performed in a posteroanterior (PA) direction with the patient in a standing position. Details of DCR have been described previously (19,32). The patients were instructed to take a forced breathing under automated voice guidance.…”

“…As shown in Figure 1A, the changes due to respiration and cardiac function are reflected as two different types of periodic changes in pixel value on DCR images. To compute the changes in pixel value for each factor of ventilation and perfusion, respectively, the changes were separated based on differences in their spatial frequency (32,37). Subsequently, the maximum density changes in the averaged pixel value (Δ max ) was determined in each 10 × 12 grid-shaped region.…”

Novel pulmonary perfusion imaging using chest digital dynamic radiography for pulmonary artery sarcoma

“…Pulmonary perfusion and ventilation images were created from chest digital dynamic radiography (DDR), captured using a flatpanel detector (AeroDR fine; Konica Minolta, Inc., Japan) and an X-ray system (RADspeed Pro; Shimadzu Corporation, Japan) using KINOSIS 1.00 (Konica Minolta, Inc.). DDR technology is a novel evaluation of pulmonary perfusion and ventilation that provides a functional assessment in 6-15 sec with no contrast agent [1,2]. It can be performed in standing or supine position [2] and requires less radiation exposure than scintigraphy.…”