[Extraction of respiratory signals from chest tomosynthesis].

OBJECTIVE: To analyze the respiratory motion of the scanned object during acquisition of digital chest tomosynthesis (CTS) using a linear model. OBJECTIVE: Respiratory signals were generated by extracting the motion of the diaphragm from the projection radiographs. The diaphragm trajectory obtained by dynamic programming (DP) was modeled and fitted, and according to the fitting of the data, the base motion curve and respiratory signal curve of the diaphragm were separated. Multipurpose chest phantom data, simulated digital Xcat phantom data and the datasets of 3 clinical patients were used to validate the performance of the proposed method. OBJECTIVE: The motion trajectory of the diaphragm extracted from multipurpose chest phantom simulation data was linear. The respiratory signals could be effectively extracted from the 3 datasets of clinical patients in different respiratory states. The correlation coefficient between the respiratory signal extracted in Xcat simulation experiment and the original design was 0.9797. OBJECTIVE: The linear model can effectively obtain the respiratory motion information of patients in real time, thus enabling the physicians to make clinical decisions on a rescan.

Determination of radiation dose and low-dose protocol for digital chest tomosynthesis using radiophotoluminescent (RPL) glass dosimeters.

PURPOSE: This study aimed to determine a low-dose protocol for digital chest tomosynthesis (DTS). METHODS: Five simulated nodules with a CT number of approximately 100 HU with size diameter of 3, 5, 8, 10, and 12 mm were inserted into an anthropomorphic chest phantom (N1 Lungman model), and then scanned by DTS system (Definium 8000) with varying tube voltage, copper filter thickness, and dose ratio. Three radiophotoluminescent (RPL) glass dosimeters, type GD-352 M with a dimension of 1.5 × 12 mm, were used to measure the entrance surface air kerma (ESAK) in each protocol. The effective dose (ED) was calculated using the recorded total dose-area-product (DAP). The signal-to-noise ratio (SNR) was determined for qualitative image quality evaluation. The image criteria and nodule detection capability were scored by two experienced radiologists. The selected low-dose protocol was further applied in a clinical study with 30 pulmonary nodule follow-up patients. RESULTS: The average ESAK obtained from the standard default protocol was 1.68 ± 0.15 mGy, while an ESAK of 0.47 ± 0.02 mGy was found for a low-dose protocol. The EDs for the default and low-dose protocols were 313.98 ± 0.72 µSv and 100.55 ± 0.28 µSv, respectively. There were small non-significant differences in the image criteria and nodule detection scoring between the low-dose and default protocols interpreted by two radiologists. The effective dose of 98.87 ± 0.08 µSv was obtained in clinical study after applying the low-dose protocol. CONCLUSIONS: The low-dose protocol obtained in this study can substantially reduce radiation dose while preserving an acceptable image quality compared to the standard protocol.

Detection of Pulmonary Nodule Growth with Chest Tomosynthesis: A Human Observer Study Using Simulated Nodules.

RATIONALE AND OBJECTIVES: Chest tomosynthesis has been suggested as a suitable alternative to CT for follow-up of pulmonary nodules. The aim of the present study was to investigate the possibility of detecting pulmonary nodule growth using chest tomosynthesis. MATERIALS AND METHODS: Simulated nodules with volumes of approximately 100 mm3 and 300 mm3 as well as additional versions with increasing volumes were created. The nodules were inserted into images from pairs of chest tomosynthesis examinations, simulating cases where the nodule had either remained stable in size or increased in size between the two imaging occasions. Nodule volume growths ranging from 11% to 252% were included. A simulated dose reduction was applied to a subset of the cases. Cases differing in terms of nodule size, dose level, and nodule position relative to the plane of image reconstruction were included. Observers rated their confidence that the nodules were stable in size or not. The rating data for the nodules that were stable in size was compared to the rating data for the nodules simulated to have increased in size using ROC analysis. RESULTS: Area under the curve values ranging from 0.65 to 1 were found. The lowest area under the curve values were found when there was a mismatch in nodule position relative to the reconstructed image plane between the two examinations. Nodule size and dose level affected the results. CONCLUSION: The study indicates that chest tomosynthesis can be used to detect pulmonary nodule growth. Nodule size, dose level, and mismatch in position relative to the image reconstruction plane in the baseline and follow-up examination may affect the precision.

Digital chest tomosynthesis: the 2017 updated review of an emerging application.

Lung cancer is the leading cause of cancer death and second most common cancer among both men and women, but most of them are detected when patients become symptomatic and in late-stage. Chest radiography (CR) is a basic technique for the investigation of lung cancer and has the benefit of convenience and low radiation dose, but detection of malignancy is often difficult. The introduction of computed tomography (CT) for screening has increased the proportion of lung cancer detected but with higher exposure dose and higher costs. Digital chest tomosynthesis (DCT), a tomographic technique, may offer an alternative to CT. DCT uses a conventional radiograph tube, a flat-panel detector, a computer-controlled tube mover and reconstruction algorithms to produce section images. It shows promise in the detection of potentially malignant lung nodules, with higher sensibility than CR, and is emerging as a low-dose and low-cost alternative to CT to improve treatment decisions. In fact, an increasing number of researchers are showing that tomosynthesis could have a role in the detection of lung cancer, in addition to its present role in breast screening. However, DCT offers some limitations, such as limited depth resolution, which may explain the difficulty in detecting pathologies in the subpleural region and the occurrence of artefacts from medical devices. Once solved these limitations and once more studies supporting its use will be available, DCT could become the first-line lung cancer screening tool among patients at considerable risk of lung cancer.

Sin-quadratic model for chest tomosynthesis respiratory signal analysis and its application in four dimensional chest tomosynthesis reconstruction.

Chest tomosynthesis (CTS) is a newly developed imaging technique which provides pseudo-3D volume anatomical information of thorax from limited-angle projections and contains much less of superimposed anatomy than the chest X-ray radiography. One of the relatively common problems in CTS is the patient respiratory motion during image acquisition, which negatively impacts the detectability. In this work, we propose a sin-quadratic model to analyze the respiratory motion during CTS scan, which is a real time method where the respiratory signal is generated by extracting the motion of diaphragm from projection radiographs. According to the estimated respiratory signal, the CTS projections were then amplitude-based sorted into four to eight phases, and an iterative reconstruction strategy with total variation regularization was adopted to reconstruct the CTS images at each phase. Simulated digital XCAT phantom data and three sets of patient data were adopted for the experiments to validate the performance of the sin-quadratic model and its application in four dimensional (4D) CTS reconstruction. Results of the XCAT phantom simulation study show that the correlation coefficient between the extracted respiratory signal and the originally designed respiratory signal is 0.9964, which suggests that the proposed model could exactly extract the respiratory signal from CTS projections. The 4D CTS reconstructions of both the phantom data and the patient data show clear reduction of motion-induced blur.

Lung cancer detection with digital chest tomosynthesis: first round results from the SOS observational study.

OBJECTIVE: Baseline results of the Studio OSservazionale (SOS), observational study, a single-arm observational study of digital chest tomosynthesis for lung cancer detection in an at-risk population demonstrated a detection rate of lung cancer comparable to that of studies that used low dose CT scan (LDCT). We present the results of the first round. METHODS: Totally 1,703 out of 1,843 (92%) subjects who had a baseline digital chest tomosynthesis underwent a first round reevaluation after 1 year. RESULTS: At first round chest digital tomosynthesis, 13 (0.7%) subjects had an indeterminate nodule larger than 5 mm and underwent low-dose CT scan for nodule confirmation. PET/CT study was obtained in 10 (0.5%) subjects and 2 subjects had a low-dose CT follow up. Surgery, either video-assisted thoracoscopic or open surgery for indeterminate pulmonary nodules was performed in 10 (0.2%) subjects. A lung cancer was diagnosed and resected in five patients. The lung cancer detection rate at first round was 0.3% (5/1,703). CONCLUSIONS: The detection rate of lung cancer at first round for tomosynthesis is comparable to rates reported for CT. In addition, results of first round digital chest tomosynthesis confirm chest tomosynthesis as a possible first-line lung cancer-screening tool.

Revisión de técnica y utilidades de la tomosíntesis digital de tórax en la actualidad / A review of current techniques and usefulness of digital chest tomosynthesis

Digital tomosynthesis (DTS) of the chest is an imaging technique composed of similar components to digital radiography (DR). Its advantages over DR: more precise diagnosis of the thoracic structure alterations, useful for confirming or ruling out suspected nodules, detection of patients at high risk of lung cancer and the monitoring of known lesions. The DTS creates coronal thoracic reconstructions with resolution superior to CT; however it is limited by its depth resolution and sensitivity to movement, occasionally hiding lesions adjacent to the pleura, diaphragm and mediastinum. The radiation dose of DTS and the cost is much lower than CT. More specific applications as well as the pulmonary nodules are under investigation, such as mycobacterial infection, cystic fibrosis and others. A basic understanding of the usefulness of thoracic DTS and its technique may be useful for the radiologist.

La Tomosíntesis digital (TSD) de tórax es una técnica de imagen compuesta por piezas similares que la radiografía digital (RD). Sus ventajas de sobre RD: diagnóstico más preciso de las alteraciones estructuras torácicas, útil para confirmar o descartar la sospecha de nódulos, detección de los pacientes de alto riesgo de cáncer pulmonar y seguimiento de lesiones conocidas. La TSD crea reconstrucciones coronales torácicas con resolución superior a TC. Sin embargo, está limitada por su resolución de profundidad y susceptibilidad al movimiento, ocultando ocasionalmente lesiones adyacentes a pleura, diafragma y mediastino. La dosis de radiación de TSD y el costo son más bajos que la TC. Más aplicaciones específicas además de los nódulos pulmonares están bajo investigación, como la infección por micobacterias, fibrosis quística y otras. Una comprensión básica de la utilidad de TSD torácica y su técnica puede ser útil para el radiólogo.

The value of chest tomosynthesis in locating a ground glass nodule (GGN) during endobronchial ultrasonography with a guide sheath: a case report.

A 74-year-old man was referred to our department for work-up of a pure ground glass nodule (GGN) on computed tomography (CT). He was suspected to have lung cancer by CT scan, but no lesion was visible on chest X-ray. Chest tomosynthesis was performed before bronchoscopy, showing a clear GGN. We could not detect a tumor signal on endobronchial ultrasonography so we relied on the chest tomosynthesis image as a guide during transbronchial biopsy. The diagnosis of adenocarcinoma was confirmed on histopathology. In this case, transbronchial biopsy under the guidance of chest tomosynthesis was useful for the diagnosis of GGN.

The diagnostic utility of endobronchial ultrasonography with a guide sheath and tomosynthesis images for ground glass opacity pulmonary lesions.

BACKGROUND: With the widespread use of computed tomography (CT), the frequency of discovering ground glass opacity (GGO) pulmonary lesions has increased. There have been some reports on surgery or transthoracic needle aspiration (TTNA) for diagnostic sampling of GGOs but none on transbronchial biopsy (TBB). The purpose of this study was to evaluate the diagnostic utility of chest tomosynthesis images and TBB through endobronchial ultrasonography with a guide sheath (EBUS-GS) for GGO. METHODS: This study included 40 patients (19 men, 21 women; age 66.9±8.7 years, mean ± standard deviation, SD). The mean lesion diameter was 22±10 mm (mean ± SD). Chest tomosynthesis images served as maps prior to bronchoscopic sampling using radial EBUS probe with a guide sheath kit. RESULTS: The overall diagnostic yield of EBUS-GS-guided TBB was 65.0% (26 of 40 lesions). In a multivariate analysis, diagnostic yield of lesions with EBUS images (79.2%, 19 of 24 cases) was significantly higher than those lesions without EBUS images detected (43.8%, 7 of 16 cases) (P=0.017). Detectability on chest tomosynthesis was not a significant contributing factor. Only one complication was observed: pneumothorax that did not require chest tube drainage. CONCLUSIONS: TBB through EBUS-GS can be considered as one of the diagnostic methods for GGO. Further technological development is required to identify the location of the target GGO lesion more precisely.