Single-exposure Dual-energy Subtraction Research Articles

Single-exposure dual-energy subtraction chest radiography: Detection of pulmonary nodules and masses in clinical practice

The purpose of this retrospective study was to evaluate the impact of energy subtraction (ES) chest radiography on the detection of pulmonary nodules and masses in daily routine. Seventy-seven patients and 25 healthy subjects were examined with a single exposure digital radiography system. Five blinded readers evaluated first the non-subtracted PA and lateral chest radiographs alone and then together with the subtracted PA soft tissue images. The size, location and number of lung nodules or masses were registered with the confidence level. CT was used as standard of reference. For the 200 total lesions, a sensitivity of 33.5-52.5% was found at non-subtracted and a sensitivity of 43.5-58.5% at energy-subtracted radiography, corresponding to a significant improvement in four of five readers (p < 0.05). However, in three of five readers the rate of false positives was higher with ES. With ES, sensitivity, but not the area under the alternative free-response receiver operating characteristics (AFROC) curve, showed a good correlation with reader experience (R = 0.90, p = 0.026). In four of five readers, the diagnostic confidence improved with ES (p = 0.0036). We conclude that single-exposure digital ES chest radiography improves detection of most pulmonary nodules and masses, but identification of nodules <1 cm and false-positive findings remain a problem.

Detection of lung cancer using single-exposure dual-energy subtraction chest radiography

The aim of this study was to evaluate the detectability of lung cancer by chest radiography with a single-exposure dual-energy subtraction (ES) method. Five radiologists read two sets of chest radiographs from 77 patients (66.5 +/- 9.6 years old) with histologically proven lung cancer measuring <or=3.0 cm and those from 77 normal subjects (65.7 +/- 9.0 years old). The observer tests were performed in two sessions: standard computed radiography (CR) images only and a combination of CR and ES images. Receiver-operating characteristic analysis was used for statistical analysis. All tumors were classified into three groups according to the appearance on thin-section CT: (1) nonsolid: tumor shadow disappearance rate (TDR) was 100%; (2) partly solid: TDR was >or=50 but <100%; (3) solid: TDR was <50%. Overall, detectability with the ES method was significantly better than that without ES (mean Az value increased from 0.7673 to 0.8265, P < 0.05). In the subgroup analysis of the nonsolid group and the solid group detectability did not change using the ES method, whereas in the partly solid group detectability with the ES method was significantly better than that without ES (mean Az value increased from 0.7162 to 0.8209, P < 0.005). The ES method improves the detectability of lung cancer by chest radiography, especially of the partly solid group.

Computerized detection of pulmonary nodules by single-exposure dual-energy computed radiography of the chest (part 1)

Objective: To clarify the usefulness of computerized detection of pulmonary nodules (PNs) in single-exposure dual-energy subtraction computed radiography (CR) images of the chest. Methods and material: Our scheme uses bone-subtracted CR (BS-CR) images, and consists of a contrast-adaptive filter for detection of the candidates for PNs and a vessel-enhancing filter for elimination of vessel opacities in the candidates for PNs. For the evaluation, 12 clinical cases with multiple PNs were used, and four radiologists participated in this study. Results: The detectability of our computer-aided diagnosis (CAD) was compared with detectabilities of radiologists. The mean true-positive (TP) number of four radiologists was 1.60±1.03, and that of the CAD was 1.83±1.34. There was no significant difference in the nodule detectabilities between the radiologists and CAD ( P=0.18). However, the false-positive (FP) rate of the CAD was 9.42±2.54 per image, whereas the mean FP rate of the radiologists was 1.40±0.64 per image. Conclusion: Computerized detection of PNs is considered to be useful in the determination of radiological diagnoses. However, reducing the number of FP findings remains an important problem to be solved.

Detection of simulated pulmonary nodules by single-exposure dual-energy computed radiography of the chest: effect of a computer-aided diagnosis system (Part 2)

Objective: To evaluate the performance of the computer-aided diagnosis (CAD) scheme on the detection of pulmonary nodules (PNs) in single-exposure dual-energy subtraction computed radiography (CR) images of the chest, and to evaluate the effect of this CAD scheme on radiologists' detectabilities. Methods and material: We compared the detectability by the CAD scheme with the detectability by 12 observers by using conventional CR (C-CR) and bone-subtracted CR (BS-CR) images of 25 chest phantoms with a low-contrast nylon nodule. Results: Both in the CAD scheme and for the observers, the detectability of BS-CR images was superior to that of C-CR images ( P<0.005). The detection performance of the CAD scheme was equal to that of the observers. The nodules detected by the CAD did not necessarily coincide with those by the observers. Thus, if observers can use the results of the CAD system as a ‘second opinion’, their detectabilities increase. Conclusion: The CAD system for detection of PNs in the single-exposure dual-energy subtraction method is promising for improving radiologists' detectabilities of PNs.

Clinical application of single dual-energy subtraction technique with digital storage-phosphor radiography

We used a single-exposure dual-energy subtraction technique with a storage-phosphor computed radiography (CR) system to evaluate various pulmonary diseases. Clinical applications of this method have been studies at our institution. In our experience, the dual-energy subtraction technique provided better visualization of pulmonary nodules, tracheobronchial abnormalities, pulmonary vascular diseases, calcification in a nodule, and rib lesions than conventional CR images did. Single-exposure dual-energy subtraction images were obtained with a sandwich technique using two storage-phosphor imaging plates with a 1-mm-thick copper filter interleaved between the two. The front plate obtains a lower kilovoltage image, whereas the back plate obtains a higher kilovoltage image. We can visualize soft tissue and bone images as well as unsubtracted digital images by the subtraction process.

Single-Exposure Dual-Energy Chest Images with Computed Radiography

Dual-energy subtraction radiography using computed radiography (CR) can aid in the detection of pulmonary abnormalities such as nodules, but the subtracted image requires higher x-ray exposure than usual to reduce quantum mottle. To reduce quantum mottle without increasing x-ray exposure, a new dual-energy subtraction algorithm was investigated that included an edge-adaptive smoothing process and a subtraction process. The signal-to-noise ratio and the image quality of this new subtracted image was significantly superior to that of conventional subtracted images. Observer performance of the subtracted digital radiography in detecting simulated pulmonary nodules was compared with original CR images and conventional subtracted digital radiography of 50 patients. A combination of an original CR image and a new subtracted CR image was significantly superior to a single original CR image or a combination of an original CR image and a conventional subtracted CR image (P < .01). The single-exposure dual-energy subtraction method is superior to the conventional subtraction method in the detection of pulmonary nodules.

Improvement of detection in computed radiography by new single-exposure dual-energy subtraction.

It is reported that the use of the dual-energy subtraction method enhances the abnormal shadow detection capability. However, because the subtracted image is significantly inferior to the original in signal-to-noise ratio (SNR), the x-ray dosage normally used for chest x-rays has not yielded subtracted images with adequate SNRs. Under these circumstances, we focus on the fact that there is a correlation between the noise contents of bone-and soft-tissue-subtracted images although there is no correlation between the signal contents of these images. We propose an algorithm that improves SNRs of subtraction images by reducing the noise only.

Single Exposure Dual-Energy Subtraction Radiography of the Upper Airways Using Computed Radiography

Single Exposure Dual-Energy Subtraction Radiography of the Upper Airways Using Computed Radiography

Single Exposure Dual-Energy Subtraction Radiography of the Upper Airways Using Computed Radiography

Single Exposure Dual-Energy Subtraction Radiography of the Upper Airways Using Computed Radiography

Single Exposure Dual-Energy Subtraction Radiography of the Upper Airways Using Computed Radiography

Single Exposure Dual-Energy Subtraction Radiography of the Upper Airways Using Computed Radiography

171. Single Exposure Dual Energy Subtraction (SEDES) による肺野腫瘤病変の性状弁別に関する研究(CR-1 胸部)

171. Single Exposure Dual Energy Subtraction (SEDES) による肺野腫瘤病変の性状弁別に関する研究(CR-1 胸部)

171. Single Exposure Dual Energy Subtraction (SEDES) による肺野腫瘤病変の性状弁別に関する研究(第 47 回総会学術大会一般研究発表予稿)

171. Single Exposure Dual Energy Subtraction (SEDES) による肺野腫瘤病変の性状弁別に関する研究(第 47 回総会学術大会一般研究発表予稿)