Dynamic Chest Radiography Research Articles

S04.6 Dynamic Chest Radiography (DCR) in cystic fibrosis: initial experience

S04.6 Dynamic Chest Radiography (DCR) in cystic fibrosis: initial experience

Utility and validity of dynamic chest radiography in cystic fibrosis (dynamic CF): an observational, non-controlled, non-randomised, single-centre, prospective study

IntroductionDynamic chest radiography (DCR) uses novel, low-dose radiographic technology to capture images of the thoracic cavity while in motion. Pulmonary function testing is important in cystic fibrosis (CF). The tolerability,...

Evaluation of Pulmonary Function by Dynamic Chest Radiography and Its Application to Multidisciplinary Computational Anatomy

Evaluation of Pulmonary Function by Dynamic Chest Radiography and Its Application to Multidisciplinary Computational Anatomy

Time-resolved quantitative evaluation of diaphragmatic motion during forced breathing in a health screening cohort in a standing position: Dynamic chest phrenicography

Objective: To assess diaphragmatic motion during forced breathing in a health screening center cohort by time-resolved quantitative analysis using dynamic chest radiography and demonstrate the characteristics and associations with demographics and pulmonary function of participants.Materials and methods: This prospective study includes 174 volunteers (99 males; median 57, range 36–93 years old) that underwent dynamic chest radiography with a flat panel detector system during forced breathing in a standing position. We automatically tracked and recorded the positions of the top of the diaphragms and the excursions on images of each participant and calculated peak motion speeds based on the data. We investigated the associations with demographics and pulmonary function statistically.Results: The average excursions of the diaphragms during forced breathing were 49.1 ± 17.0 mm (right; mean ± standard deviation) and 52.1 ± 15.9 mm (left). The peak motion speeds were 26.7 ± 10.0 mm/s (right) and 32.2 ± 12.4 mm/s (left) in the inspiratory phase and 22.1 ± 12.7 mm/s (right) and 24.3 ± 10.3 mm/s (left) in the expiratory phase. Excursions and peak motion speeds of the left diaphragm were significantly greater than the right. Higher body mass index (BMI) and vital capacity (VC) were associated with greater excursions and faster peak motion speeds of the diaphragms.Conclusions: Time-resolved quantitative analysis of the diaphragms with dynamic chest radiography demonstrated the characteristics of diaphragmatic motion during forced breathing in a health screening cohort. Higher BMI and VC were associated with excursions and peak motion speeds of the diaphragms.

Detection of Pulmonary Embolism Based on Reduced Changes in Radiographic Lung Density During Cardiac Beating Using Dynamic Flat-panel Detector: An Animal-based Study

To assess the capacity of dynamic flat-panel detector imaging without the use of contrast media to detect pulmonary embolism (PE) based on temporal changes in radiographic lung density during cardiac beating. Sequential chest radiographs of six pigs were acquired using a dynamic flat-panel detector system. A porcine model of PE was developed, and temporal changes in pixel values in the imaged lungs were analyzed during a whole cardiac cycle. Mean differences in temporal changes in pixel values between affected and unaffected lobes were assessed using the paired t test. To facilitate visual evaluation, temporal changes in pixel values were depicted using a colorimetric scale and were compared to the findings of contrast-enhanced images. Affected lobes exhibited a mean reduction of 49.6% in temporal changes in pixel values compared to unaffected lobes within the same animals, and a mean reduction of 41.3% compared to that before vessel blockage in the same lobe. All unaffected lobes exhibited significantly-increased changes in pixel values after vessel blockage (p < 0.01). In all PE models, there were color-deficient areas with shapes and locations that matched well with the perfusion defects confirmed in the corresponding contrast-enhanced images. Dynamic chest radiography enables the detection of perfusion defects in the lobe unit based on temporal changes in image density, even without the use of contrast media. Quantification and visualization techniques provide a better understanding of the circulation-induced changes depicted in dynamic chest radiographs.

Decreased and slower diaphragmatic motion during forced breathing in severe COPD patients: Time-resolved quantitative analysis using dynamic chest radiography with a flat panel detector system

ObjectiveTo assess the diaphragmatic motion in chronic obstructive pulmonary disease (COPD) patients during forced breathing by time-resolved quantitative analysis using dynamic chest radiography and to demonstrate the characteristics and the difference from that in normal subjects. Materials and methodsThirty-one COPD patients and a matched control of 31 normal subjects on age, sex, height, and weight, who underwent chest radiographs during forced breathing using dynamic chest radiography, were included in this study. COPD patients were classified based on the criteria of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) (GOLD 1, n = 3; GOLD 2, n = 12; GOLD 3, n = 13; GOLD 4, n = 3). We measured excursions and peak motion speeds of the diaphragms for each participant. We compared the results among GOLD 1/2, GOLD 3/4 groups and normal subjects and investigated associations between the data, and participants’ demographics, or pulmonary function. ResultsThe excursions of bilateral diaphragms were significantly decreased in the GOLD 3/4 group relative to normal subjects (right, 39.8 ± 15.3 mm vs. 52.7 ± 15.1 mm, P = 0.030; left, 43.7 ± 14.0 mm vs. 56.9 ± 15.5 mm, P = 0.017; mean ± standard deviation) and the GOLD 1/2 group (right, 39.8 ± 15.3 mm vs. 54.4 ± 16.7 mm, P = 0.036; left, 43.7 ± 14.0 mm vs. 60.5 ± 13.9 mm, P = 0.008). The peak motion speeds of the left diaphragm in the inspiratory phase were slower in the GOLD 1/2 group than in normal subjects (24.5 ± 8.0 mm/s vs. 33.6 ± 14.0 mm/s, P = 0.038), and in the GOLD 3/4 group than in normal subjects (25.6 ± 6.8 mm/s vs. 33.6 ± 14.0 mm/s, P = 0.067). The excursions of the diaphragms showed correlation with VC, %VC, and FEV1, while the peak motion speeds showed no significant correlation with pulmonary function tests. ConclusionsTime-resolved quantitative analysis of diaphragms with dynamic chest radiography indicated differences in diaphragmatic motion between COPD groups and normal subjects during forced breathing. The excursions of the diaphragms during forced breathing were significantly lower in the GOLD 3/4 group than those in the GOLD 1/2 group and normal subjects.

Recovery of 3D rib motion from dynamic chest radiography and CT data using local contrast normalization and articular motion model.

Dynamic chest radiography (2D x-ray video) is a low-dose and cost-effective functional imaging method with high temporal resolution. While the analysis of rib-cage motion has been shown to be effective for evaluating respiratory function, it has been limited to 2D. We aim at 3D rib-motion analysis for high temporal resolution while keeping the radiation dose at a level comparable to conventional examination. To achieve this, we developed a method for automatically recovering 3D rib motion based on 2D-3D registration of x-ray video and single-time-phase computed tomography. We introduce the following two novel components into the conventional intensity-based 2D-3D registration pipeline: (1) a rib-motion model based on a uniaxial joint to constrain the search space and (2) local contrast normalization (LCN) as a pre-process of x-ray video to improve the cost function of the optimization parameters, which is often called the landscape. The effects of each component on the registration results were quantitatively evaluated through experiments using simulated images and real patients' x-ray videos obtained in a clinical setting. The rotation-angle error of the rib and the mean projection contour distance (mPCD) were used as the error metrics. The simulation experiments indicate that the proposed uniaxial joint model improved registration accuracy. By searching the rotation axis along with the rotation angle of the ribs, the rotation-angle error and mPCD significantly decreased from 2.246 ± 1.839° and 1.148 ± 0.743mm to 1.495 ± 0.993° and 0.742 ± 0.281mm, compared to simply applying De Troyer's model. The real-image experiments with eight patients demonstrated that LCN improved the cost function space; thus, robustness in optimization resulting in an average mPCD of 1.255 ± 0.615mm. We demonstrated that an anatomical-knowledge based constraint and an intensity normalization, LCN, significantly improved robustness and accuracy in rib-motion reconstruction using chest x-ray video.

Difference in the craniocaudal gradient of the maximum pixel value change rate between chronic obstructive pulmonary disease patients and normal subjects using sub-mGy dynamic chest radiography with a flat panel detector system

ObjectivesTo compare the craniocaudal gradients of the maximum pixel value change rate (MPCR) during tidal breathing between chronic obstructive pulmonary disease (COPD) patients and normal subjects using dynamic chest radiography. Materials and methodsThis prospective study was approved by the institutional review board and all participants provided written informed consent. Forty-three COPD patients (mean age, 71.6±8.7 years) and 47 normal subjects (non-smoker healthy volunteers) (mean age, 54.8±9.8 years) underwent sequential chest radiographs during tidal breathing in a standing position using dynamic chest radiography with a flat panel detector system. We evaluated the craniocaudal gradient of MPCR. The results were analyzed using an unpaired t-test and the Tukey–Kramer method. ResultsThe craniocaudal gradients of MPCR in COPD patients were significantly lower than those in normal subjects (right inspiratory phase, 75.5±48.1 vs. 108.9±42.0s−1cm−1, P<0.001; right expiratory phase, 66.4±40.6 vs. 89.8±31.6s−1cm−1, P=0.003; left inspiratory phase, 75.5±48.2 vs. 108.2±47.2s−1cm−1, P=0.002; left expiratory phase, 60.9±38.2 vs. 84.3±29.5s−1cm−1, P=0.002). No significant differences in height, weight, or BMI were observed between COPD and normal groups. In the sub-analysis, the gradients in severe COPD patients (global initiative for chronic obstructive lung disease [GOLD] 3 or 4, n=26) were significantly lower than those in mild COPD patients (GOLD 1 or 2, n=17) for both right and left inspiratory/expiratory phases (all P≤0.005). ConclusionsA decrease of the craniocaudal gradient of MPCR was observed in COPD patients. The craniocaudal gradient was lower in severe COPD patients than in mild COPD patients.

Difference in diaphragmatic motion during tidal breathing in a standing position between COPD patients and normal subjects: Time-resolved quantitative evaluation using dynamic chest radiography with flat panel detector system (“dynamic X-ray phrenicography”)

ObjectivesTo quantitatively compare diaphragmatic motion during tidal breathing in a standing position between chronic obstructive pulmonary disease (COPD) patients and normal subjects using dynamic chest radiography. Materials and methodsThirty-nine COPD patients (35 males; age, 71.3±8.4years) and 47 normal subjects (non-smoker healthy volunteers) (20 males; age, 54.8±9.8years) underwent sequential chest radiographs during tidal breathing using dynamic chest radiography with a flat panel detector system. We evaluated the excursions and peak motion speeds of the diaphragms. The results were analyzed using an unpaired t-test and a multiple linear regression model. ResultsThe excursions of the diaphragms in COPD patients were significantly larger than those in normal subjects (right, 14.7±5.5mm vs. 10.2±3.7mm, respectively, P<0.001; left, 17.2±4.9mm vs. 14.9±4.2mm, respectively, P=0.022). Peak motion speeds in inspiratory phase were significantly faster in COPD patients compared to normal subjects (right, 16.3±5.0mm/s vs. 11.8±4.2mm/s, respectively, P<0.001; left, 18.9±4.9mm/s vs. 16.7±4.0mm/s, respectively, P=0.022). The multivariate analysis demonstrated that having COPD and higher body mass index were independently associated with increased excursions of the bilateral diaphragm (all P<0.05), after adjusting for other clinical variables. ConclusionsTime-resolved quantitative evaluation of the diaphragm using dynamic chest radiography demonstrated that the diaphragmatic motion during tidal breathing in a standing position is larger and faster in COPD patients than in normal subjects.

Time-Resolved Quantitative Analysis of the Diaphragms During Tidal Breathing in a Standing Position Using Dynamic Chest Radiography with a Flat Panel Detector System (“Dynamic X-Ray Phrenicography”): Initial Experience in 172 Volunteers

Diaphragmatic motion in a standing position during tidal breathing remains unclear. The purpose of this observational study was to evaluate diaphragmatic motion during tidal breathing in a standing position in a health screening center cohort using dynamic chest radiography in association with participants' demographic characteristics. One hundred seventy-two subjects (103 men; aged 56.3 ± 9.8 years) underwent sequential chest radiographs during tidal breathing using dynamic chest radiography with a flat panel detector system. We evaluated the excursions of and peak motion speeds of the diaphragms. Associations between the excursions and participants' demographics (gender, height, weight, body mass index [BMI], smoking history, tidal volume, vital capacity, and forced expiratory volume) were investigated. The average excursion of the left diaphragm (14.9 ± 4.6 mm, 95% CI 14.2-15.5 mm) was significantly larger than that of the right (11.0 ± 4.0 mm, 95% CI 10.4-11.6 mm) (P <0.001). The peak motion speed of the left diaphragm (inspiratory, 16.6 ± 4.2 mm/s; expiratory, 13.7 ± 4.2 mm/s) was significantly faster than that of the right (inspiratory, 12.4 ± 4.4 mm/s; expiratory, 9.4 ± 3.8 mm/s) (both P <0.001). Both simple and multiple regression models demonstrated that higher BMI and higher tidal volume were associated with increased excursions of the bilateral diaphragm (all P <0.05). The average excursions of the diaphragms are 11.0 mm (right) and 14.9 mm (left) during tidal breathing in a standing position. The diaphragmatic motion of the left is significantly larger and faster than that of the right. Higher BMI and tidal volume are associated with increased excursions of the bilateral diaphragm.

Dynamic chest radiography: flat-panel detector (FPD) based functional X-ray imaging.

Dynamic chest radiography is a flat-panel detector (FPD)-based functional X-ray imaging, which is performed as an additional examination in chest radiography. The large field of view (FOV) of FPDs permits real-time observation of the entire lungs and simultaneous right-and-left evaluation of diaphragm kinetics. Most importantly, dynamic chest radiography provides pulmonary ventilation and circulation findings as slight changes in pixel value even without the use of contrast media; the interpretation is challenging and crucial for a better understanding of pulmonary function. The basic concept was proposed in the 1980s; however, it was not realized until the 2010s because of technical limitations. Dynamic FPDs and advanced digital image processing played a key role for clinical application of dynamic chest radiography. Pulmonary ventilation and circulation can be quantified and visualized for the diagnosis of pulmonary diseases. Dynamic chest radiography can be deployed as a simple and rapid means of functional imaging in both routine and emergency medicine. Here, we focus on the evaluation of pulmonary ventilation and circulation. This review article describes the basic mechanism of imaging findings according to pulmonary/circulation physiology, followed by imaging procedures, analysis method, and diagnostic performance of dynamic chest radiography.

Quantitative analysis of rib kinematics based on dynamic chest bone images: preliminary results.

An image-processing technique for separating bones from soft tissue in static chest radiographs has been developed. The present study was performed to evaluate the usefulness of dynamic bone images in quantitative analysis of rib movement. Dynamic chest radiographs of 16 patients were obtained using a dynamic flat-panel detector and processed to create bone images by using commercial software (Clear Read BS, Riverain Technologies). Velocity vectors were measured in local areas on the dynamic images, which formed a map. The velocity maps obtained with bone and original images for scoliosis and normal cases were compared to assess the advantages of bone images. With dynamic bone images, we were able to quantify and distinguish movements of ribs from those of other lung structures accurately. Limited rib movements of scoliosis patients appeared as a reduced rib velocity field, resulting in an asymmetrical distribution of rib movement. Vector maps in all normal cases exhibited left/right symmetric distributions of the velocity field, whereas those in abnormal cases showed asymmetric distributions because of locally limited rib movements. Dynamic bone images were useful for accurate quantitative analysis of rib movements. The present method has a potential for an additional functional examination in chest radiography.

Dynamic dual-energy chest radiography: a potential tool for lung tissue motion monitoring and kinetic study

Dual-energy chest radiography has the potential to provide better diagnosis of lung disease by removing the bone signal from the image. Dynamic dual-energy radiography is now possible with the introduction of digital flat-panel detectors. The purpose of this study is to evaluate the feasibility of using dynamic dual-energy chest radiography for functional lung imaging and tumor motion assessment. The dual-energy system used in this study can acquire up to 15 frames of dual-energy images per second. A swine animal model was mechanically ventilated and imaged using the dual-energy system. Sequences of soft-tissue images were obtained using dual-energy subtraction. Time subtracted soft-tissue images were shown to be able to provide information on regional ventilation. Motion tracking of a lung anatomic feature (a branch of pulmonary artery) was performed based on an image cross-correlation algorithm. The tracking precision was found to be better than 1 mm. An adaptive correlation model was established between the above tracked motion and an external surrogate signal (temperature within the tracheal tube). This model is used to predict lung feature motion using the continuous surrogate signal and low frame rate dual-energy images (0.1–3.0 frames per second). The average RMS error of the prediction was (1.1 ± 0.3) mm. The dynamic dual energy was shown to be potentially useful for lung functional imaging such as regional ventilation and kinetic studies. It can also be used for lung tumor motion assessment and prediction during radiation therapy.

Ventilatory impairment detection based on distribution of respiratory-induced changes in pixel values in dynamic chest radiography: a feasibility study

Decreased ventilation is observed on chest radiographs as small changes in X-ray translucency, and ventilatory impairments can therefore be detected by analyzing the distribution of respiratory-induced changes in pixel value. This study was performed to develop a ventilatory impairment detection method based on the distribution of respiratory-induced changes in pixel values. Sequential chest radiographs during respiration were obtained using a dynamic flat panel detector system. Respiratory-induced changes in pixel value were measured in each local area and then compared for symmetrical positions in both lungs, which were located at the same distance from the axis of the thorax at the same level. The right-left symmetry was assessed in 20 clinical cases (Abnormal, 14; Normal, 6). In normal controls, the distribution was symmetrical, and there were good correlations of the pixel value changes in both lungs at symmetrical positions (r = 0.66 ± 0.05). In contrast, abnormal cases did not show a symmetrical distribution of pixel value changes (r = 0.40 ± 0.23) due to ventilation abnormalities observed as reductions in pixel value changes. Ventilatory impairment could be detected as deviation from the right-left symmetry of respiratory-induced changes in pixel value. In particular, the present method could be useful for detecting unilateral abnormalities. However, to detect bilateral abnormalities, further studies are required to develop multilevel detection methods combined with several methods of pattern analysis.

Development of pulmonary blood flow evaluation method with a dynamic flat-panel detector: quantitative correlation analysis with findings on perfusion scan

Pulmonary blood flow is reflected in dynamic chest radiographs as changes in X-ray translucency, i.e., pixel values. Thus, decreased blood flow should be observed as a reduction of the variation of X-ray translucency. We performed the present study to investigate the feasibility of pulmonary blood flow evaluation with a dynamic flat-panel detector (FPD). Sequential chest radiographs of 14 subjects were obtained with a dynamic FPD system. The changes in pixel value in each local area were measured and mapped on the original image by use of a gray scale in which small and large changes were shown in white and black, respectively. The resulting images were compared to the findings in perfusion scans. The cross-correlation coefficients of the changes in pixel value and radioactivity counts in each local area were also computed. In all patients, pulmonary blood flow disorder was indicated as a reduction of changes in pixel values on the mapping image, and a correlation was observed between the distribution of changes in pixel value and those in radioactivity counts (0.7 <or= r, 3 cases; 0.4 <or= r < 0.7, 7 cases; 0.2 <or= r < 0.4, 4 cases). The results indicated that the distribution of changes in pixel value could provide a relative measure related to pulmonary blood flow. The present method is potentially useful for evaluating pulmonary blood flow as an additional examination in conventional chest radiography.

Tracheomalacia in Adults with Cystic Fibrosis: Determination of Prevalence and Severity with Dynamic Cine CT

HomeRadiologyVol. 275, No. 3 PreviousNext CommunicationsFree AccessErrataTracheomalacia in Adults with Cystic Fibrosis: Determination of Prevalence and Severity with Dynamic Cine CTShaunagh McDermott, Sinead C. Barry, Eoin E. Judge, Susan Collins, Pim A. de Jong, Harm A. W. M. Tiddens, Edward F. McKone, Charles G. Gallagher, Jonathan D. DoddShaunagh McDermott, Sinead C. Barry, Eoin E. Judge, Susan Collins, Pim A. de Jong, Harm A. W. M. Tiddens, Edward F. McKone, Charles G. Gallagher, Jonathan D. DoddShaunagh McDermottSinead C. BarryEoin E. JudgeSusan CollinsPim A. de JongHarm A. W. M. TiddensEdward F. McKoneCharles G. GallagherJonathan D. DoddPublished Online:May 21 2015https://doi.org/10.1148/radiol.2015154012MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In Originally published in:Radiology 2009;252(2):577–586 DOI: 10.1148/radiol.2522081956Erratum in:Radiology 2015;275(3):934 DOI:10.1148/radiol.2015154012In the author list, the third author should be listed as Eoin P. Judge.Article HistoryPublished online: May 21 2015Published in print: June 2015 FiguresReferencesRelatedDetailsCited ByThat antibiotic prophylaxis should be used in children with repaired oesophageal atresia and or trachea-oesophageal fistula – The case in favourPeter J.Merkus2016 | Paediatric Respiratory Reviews, Vol. 18Accompanying This ArticleTracheomalacia in Adults with Cystic Fibrosis: Determination of Prevalence and Severity with Dynamic Cine CTAug 1 2009RadiologyRecommended Articles Allergic Bronchopulmonary Aspergillosis in Cystic Fibrosis: MR Imaging of Airway Mucus Contrasts as a Tool for DiagnosisRadiology2017Volume: 285Issue: 1pp. 261-269Use of Dynamic Chest Radiography to Assess Treatment of Pulmonary Exacerbations in Cystic FibrosisRadiology2022Volume: 303Issue: 3pp. 675-681Three-dimensional Isotropic Functional Imaging of Cystic Fibrosis Using Oxygen-enhanced MRI: Comparison with Hyperpolarized 3He MRIRadiology2018Volume: 290Issue: 1pp. 229-237Self-gated Non–Contrast-enhanced Functional Lung MR Imaging for Quantitative Ventilation Assessment in Patients with Cystic FibrosisRadiology2016Volume: 283Issue: 1pp. 242-251Quantification of Cystic Fibrosis Lung Disease with Radiomics-based CT ScoresRadiology: Cardiothoracic Imaging2020Volume: 2Issue: 6See More RSNA Education Exhibits CF-SCRIbeR Study: Cystic Fibrosis Structured Radiology Report, Standardisation of CT Reporting in Patients with Pulmonary Cystic Fibrosis (CF)Digital Posters2018Imaging in Cystic Fibrosis Follow-up: What is the News?Digital Posters2019Cystic Fibrosis in Adult Patients: A Pictorial Review of Common and Uncommon Abdominal Manifestations Digital Posters2018 RSNA Case Collection Pulmonary manifestations of cystic fibrosisRSNA Case Collection2020Allergic Bronchopulmonary AspergillosisRSNA Case Collection2021Mounier-Kuhn syndromeRSNA Case Collection2020 Vol. 275, No. 3 Metrics Altmetric Score PDF download

胸部Ｘ線動態撮影の再現性の検証‐ピクセル値の呼吸性変化‐

Dynamic chest radiography using a flat panel detector (FPD) with a large field of view is expected to be a useful pulmonary functional evaluation method based on the respiratory changes in pixel value. For clinical use as a follow-up and therapeutic evaluation tool, the system must have a high degree of reproducibility in measurements of pixel values. The present study was performed to investigate the reproducibility of respiratory changes in pixel values. Dynamic chest radiographs of five normal subjects and one patient were obtained. Imaging was performed twice in each subject. The slope (X-ray translucency variation) was then calculated from the changes in pixel value from distance lung apex-diaphragm, and the slopes of two sequences were compared. The results showed there were no significant differences in changes in pixel value between the two sequences in all normal subject (5 males, p>0.05). The results indicated that the present method has reproducibility for measuring pulmonary function and also has potential as a tool for follow-up and therapeutic evaluation.

動画対応フラットパネルディテクタによる肺機能画像診断法：肺シンチグラフィ所見との比較

Pulmonary ventilation and circulation dynamics are reflected on dynamic chest radiographs as changes in X-ray translucency,i.e., pixel values. The present study was performed to develop a pulmonary functional evaluation method based on the changes in pixel value, and to investigate the clinical usefulness of our method. Sequential chest radiographs of 20 subjects (abnormal,n=12; normal,n=8) during respiration were obtained with a dynamic flat-panel detector (FPD) system. The average pixel value in each local area was measured tracking the same area. To facilitate visual evaluation, the results were mapped on the original image using a grayscale in which small changes were shown in black and large changes were shown in white. In our clinical evaluation in comparison with a pulmonary scintigraphy, pulmonary ventilation disorder was indicated as a reduction of changes in pixel values. In many patients, there was a correlation between our result and a pulmonary scintigraphy (0.7<r, 4 cases; 0.4<r<or=0.7, 6 cases; 0.2<r<or=0.4, 1 case; 0<r<or=0.2, 1 case). The present method with real-time computer analysis is expected to be a rapid and simple method for evaluating pulmonary function and as an additional examination in conventional chest radiography.

Development of functional chest imaging with a dynamic flat-panel detector (FPD)

Dynamic FPD permits the acquisition of distortion-free radiographs with a large field of view and high image quality. In the present study, we investigated the feasibility of functional imaging for evaluating the pulmonary sequential blood distribution with an FPD, based on changes in pixel values during cardiac pumping. Dynamic chest radiographs of seven normal subjects were obtained in the expiratory phase by use of an FPD system. We measured the average pixel value in each region of interest that was located manually in the heart and lung areas. Subsequently, inter-frame differences and differences from a minimum-intensity projection image, which was created from one cardiac cycle, were calculated. These difference values were then superimposed on dynamic chest radiographs in the form of a color display, and sequential blood distribution images and a blood distribution map were created. The results were compared to typical data on normal cardiac physiology. The clinical effectiveness of our method was evaluated in a patient who had abnormal pulmonary blood flow. In normal cases, there was a strong correlation between the cardiac cycle and changes in pixel value. Sequential blood distribution images showed a normal pattern at determined by the physiology of pulmonary blood flow, with a symmetric distribution and no blood flow defects throughout the entire lung region. These findings indicated that pulmonary blood flow was reflected on dynamic chest radiographs. In an abnormal case, a defect in blood flow was shown as defective in color in a blood distribution map. The present method has the potential for evaluation of local blood flow as an optional application in general chest radiography.

Development of a cardiac evaluation method using a dynamic flat-panel detector (FPD) system: a feasibility study using a cardiac motion phantom

The purpose of this study is to investigate the feasibility of cardiac evaluation with a dynamic flat-panel detector (FPD), based on changes in pixel values during cardiac pumping. To investigate the feasibility of cardiac evaluation with a dynamic flat-panel detector (FPD), based on changes in pixel values during cardiac pumping. Sequential radiographs of a cardiac motion phantom and water-equivalent material step were obtained with an FPD system. Various combinations of cardiac output and heart rate were evaluated with and without contrast medium. The ventricular area and summation of pixel values in the ventricles were measured. The ejection fraction (EF) was calculated based on the rate of changes and then compared to EF obtained from computed tomography images. In addition, slight changes in pixel values were visualized by use of inter-frame subtraction and color-mapping. The result of a clinical case was examined according to cardiac physiology. There were strong correlations between EF and our results. There was no significant difference between the findings with and without contrast medium. When the heart rate was greater than 60 bpm, EF obtained with our method were underestimated. It is necessary for a patient to be examined at an imaging rate between 7.5 and 10 fps at least. In addition, a +/-1.2% change in pixel value was equivalent to a +/-10 mm change in the thickness of water. Color-mapping images were supported by cardiac physiology. Evaluating changes in pixel values on dynamic chest radiography with FPD has the potential to demonstrate cardiac function without contrast medium. Inter-frame subtraction and color-mapping are very useful for interpreting changes in pixel value as velocities of blood flow.