ABSTRACT
AIM: To evaluate a novel deep-learning denoising method for ultra-low dose CT (ULDCT) in the assessment of coronary artery calcium score (CACS). MATERIALS AND METHODS: Sixty adult patients who underwent two unenhanced chest CT examinations, a normal dose CT (NDCT) and an ULDCT, were enrolled prospectively between September 2017 to December 201. A special training set was created to learn the characteristics of the real noise affecting the ULDCT implementing a fully convolutional neural network with batch normalisation. Subsequently, the 60 ULDCTs of the evaluation set were denoised. Two blinded radiologists assessed the NDCT, ULDCT, and denoised-ULDCT (DULDCT), assigning a CACS and categorised each scan as having a score above or below 100 and presence of calcifications (score 0 versus >0). Statistical analysis was used to evaluate the agreement between the readers and differences in CACSs between each imaging method. RESULTS: After excluding one patient, the cohort included 59 patients (median age 67 years, 58% men). The ULDCT median effective radiation dose (ERD) was 0.172 mSv, which was 2.8% of the NDCT median ERD. Denoising improved the signal-to-noise ratio by 27.7% (p<0.001). Interobserver agreement was almost perfect between readers (intraclass correlation coefficient >0.993). CACSs were lower for ULDCT and DULDCT as compared to the NDCT (p ≤ 0.001). In differentiating between the presence and absence of coronary artery calcifications, DULDCT showed greater accuracy (98-100%) and positive likelihood ratio (14.29->99) compared to ULDCT (92% and 2.78, respectively). CONCLUSION: DULCT significantly reduced the image noise and better identified patients with no coronary artery calcifications than native ULDCT.
Subject(s)
Calcium , Deep Learning , Adult , Aged , Coronary Vessels/diagnostic imaging , Female , Humans , Lung , Male , Radiation Dosage , Tomography, X-Ray Computed/methodsABSTRACT
The purpose of this study is to determine the incidence of primary breast cancer (PBC) detected on (18) F-fluorodeoxyglucose (FDG) positron emission tomography (PET)-computed tomography (CT) in patients with a known diagnosis of non-mammary malignancies. A database search was performed to identify patients with non-mammary malignancies who had undergone staging with FDG PET-CT at a single institution between September 2005 and September 2011 and with the word "breast" reported in the PET-CT dictation. Additional breast imaging studies, clinical data, and the final histopathology of the breast lesions were correlated with the PET-CT images. Of 1951 patients who underwent PET/CT, 440 incidental breast lesions were identified in 438 patients. Of these 440 lesions, 195 (45 %) were benign, 160 (37 %) malignant, and 85 (19 %) missing data. A total of 25 PBCs were diagnosed; with a median size of 1.8 cm (range 0.8-10.7 cm); and a median SUVmax of 4.4 (range 1.7-17.6). There were 19 invasive ductal cancers, 1 invasive lobular cancer, 2 papillary cancers, 1 tubular cancer, 1 sarcomatoid cancer, and 1 ductal carcinoma in situ. Eight patients had regional nodal disease. Mammography revealed the PBC in 19 of 23 tumors (83 %), sonography in 22 of 23 (96 %). Six percent (25 of 440) of incidental breast lesions identified on FDG PET-CT represent PBCs; more than half were at an early stage and potentially curable.
Subject(s)
Breast Neoplasms/diagnosis , Incidental Findings , Positron-Emission Tomography , Tomography, X-Ray Computed , Biopsy , Breast Neoplasms/pathology , Female , Fluorodeoxyglucose F18 , Humans , Image Interpretation, Computer-Assisted , Mammography , Multimodal Imaging/methods , Tumor BurdenABSTRACT
OBJECTIVE: To investigate the effect of recognition of a previously encountered radiograph on consistency of response in localized pulmonary nodules. METHODS: 13 radiologists interpreted 40 radiographs each to locate pulmonary nodules. A few days later, they again interpreted 40 radiographs. Half of the images in the second set were new. We asked the radiologists whether each image had been in the first set. We used Fisher's exact test and Kruskal-Wallis test to evaluate the correlation between recognition of an image and consistency in its interpretation. We evaluated the data using all possible recognition levels-definitely, probably or possibly included vs definitely, probably or possibly not included by collapsing the recognition levels into two and by eliminating the "possibly included" and "possibly not included" scores. RESULTS: With all but one of six methods of looking at the data, there was no significant correlation between consistency in interpretation and recognition of the image. When the possibly included and possibly not included scores were eliminated, there was a borderline statistical significance (p = 0.04) with slightly greater consistency in interpretation of recognized than that of non-recognized images. CONCLUSION: We found no convincing evidence that radiologists' recognition of images in an observer performance study affects their interpretation on a second encounter. ADVANCES IN KNOWLEDGE: Conscious recognition of chest radiographs did not result in a greater degree of consistency in the tested interpretation than that in the interpretation of images that were not recognized.
Subject(s)
Clinical Competence , Radiology , Solitary Pulmonary Nodule/diagnostic imaging , Humans , Observer Variation , Radiography , Reproducibility of Results , Statistics, NonparametricABSTRACT
OBJECTIVES: Choosing an acceptance radius or proximity criterion is necessary to analyse free-response receiver operating characteristic (FROC) observer performance data. This is currently subjective, with little guidance in the literature about what is an appropriate acceptance radius. We evaluated varying acceptance radii in a nodule detection task in chest radiography and suggest guidelines for determining an acceptance radius. METHODS: 80 chest radiographs were chosen, half of which contained nodules. We determined each nodule's centre. 21 radiologists read the images. We created acceptance radii bins of <5 pixels, <10 pixels, <20 pixels and onwards up to <200 and 200+ pixels. We counted lesion localisations in each bin and visually compared marks with the borders of nodules. RESULTS: Most reader marks were tightly clustered around nodule centres, with tighter clustering for smaller than for larger nodules. At least 70% of readers' marks were placed within <10 pixels for small nodules, <20 pixels for medium nodules and <30 pixels for large nodules. Of 72 inspected marks that were less than 50 pixels from the centre of a nodule, only 1 fell outside the border of a nodule. CONCLUSION: The acceptance radius should be based on the larger nodule sizes. For our data, an acceptance radius of 50 pixels would have captured all but 2 reader marks within the borders of a nodule, while excluding only 1 true-positive mark. The choice of an acceptance radius for FROC analysis of observer performance studies should be based on the size of larger abnormalities.
Subject(s)
ROC Curve , Radiographic Image Interpretation, Computer-Assisted/methods , Radiography, Thoracic/methods , Solitary Pulmonary Nodule/diagnostic imaging , Tomography, X-Ray Computed/methods , Humans , Observer Variation , Radiographic Image Enhancement/methods , Reproducibility of Results , Sensitivity and Specificity , Tomography, X-Ray Computed/adverse effectsABSTRACT
OBJECTIVE: Laboratory observer performance measurements, receiver operating characteristic (ROC) and free-response ROC (FROC) differ from actual clinical interpretations in several respects, which could compromise their clinical relevance. The objective of this study was to develop a method for quantifying the clinical relevance of a laboratory paradigm and apply it to compare the ROC and FROC paradigms in a nodule detection task. METHODS: The original prospective interpretations of 80 digital chest radiographs were classified by the truth panel as correct (C=1) or incorrect (C=0), depending on correlation with additional imaging, and the average of C was interpreted as the clinical figure of merit. FROC data were acquired for 21 radiologists and ROC data were inferred using the highest ratings. The areas under the ROC and alternative FROC curves were used as laboratory figures of merit. Bootstrap analysis was conducted to estimate conventional agreement measures between laboratory and clinical figures of merit. Also computed was a pseudovalue-based image-level correctness measure of the laboratory interpretations, whose association with C as measured by the area (rAUC) under an appropriately defined relevance ROC curve, is as a measure of the clinical relevance of a laboratory paradigm. RESULTS: Low correlations (e.g. κ=0.244) and near chance level rAUC values (e.g. 0.598), attributable to differences between the clinical and laboratory paradigms, were observed. The absolute width of the confidence interval was 0.38 for the interparadigm differences of the conventional measures and 0.14 for the difference of the rAUCs. CONCLUSION: The rAUC measure was consistent with the traditional measures but was more sensitive to the differences in clinical relevance. A new relevance ROC method for quantifying the clinical relevance of a laboratory paradigm is proposed.
Subject(s)
Algorithms , Image Interpretation, Computer-Assisted/methods , Lung Neoplasms/diagnostic imaging , ROC Curve , Radiographic Image Enhancement/methods , Radiography, Thoracic/methods , Solitary Pulmonary Nodule/diagnostic imaging , Adult , Aged , Humans , Male , Middle Aged , Observer Variation , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
The reversed halo sign is characterised by a central ground-glass opacity surrounded by denser air-space consolidation in the shape of a crescent or a ring. It was first described on high-resolution CT as being specific for cryptogenic organising pneumonia. Since then, the reversed halo sign has been reported in association with a wide range of pulmonary diseases, including invasive pulmonary fungal infections, paracoccidioidomycosis, pneumocystis pneumonia, tuberculosis, community-acquired pneumonia, lymphomatoid granulomatosis, Wegener granulomatosis, lipoid pneumonia and sarcoidosis. It is also seen in pulmonary neoplasms and infarction, and following radiation therapy and radiofrequency ablation of pulmonary malignancies. In this article, we present the spectrum of neoplastic and non-neoplastic diseases that may show the reversed halo sign and offer helpful clues for assisting in the differential diagnosis. By integrating the patient's clinical history with the presence of the reversed halo sign and other accompanying radiological findings, the radiologist should be able to narrow the differential diagnosis substantially, and may be able to provide a presumptive final diagnosis, which may obviate the need for biopsy in selected cases, especially in the immunosuppressed population.
Subject(s)
Kidney Diseases/diagnostic imaging , Lung Diseases/diagnostic imaging , Neoplasms/diagnostic imaging , Tomography, X-Ray Computed/methods , Diagnosis, Differential , HumansSubject(s)
Arteriovenous Fistula/etiology , Carcinoma, Renal Cell/secondary , Kidney Neoplasms , Lung Neoplasms/secondary , Pulmonary Artery/abnormalities , Pulmonary Veins/abnormalities , Aged , Arteriovenous Fistula/diagnostic imaging , Carcinoma, Renal Cell/diagnostic imaging , Female , Humans , Lung Neoplasms/diagnostic imaging , Pulmonary Artery/diagnostic imaging , Pulmonary Veins/diagnostic imaging , Radionuclide Imaging , Tomography, X-Ray Computed/methodsABSTRACT
PURPOSE: To determine if daclizumab, an interleukin-2 antagonist, reduced the severity of reperfusion edema in lung transplant recipients. MATERIALS AND METHODS: Eighty-five patients who were to undergo 86 consecutive lung transplants were included; 43 (50%) received daclizumab in addition to conventional immunosuppression. Patients were assigned to one of the following groups: control, right allograft; control, left allograft; daclizumab treated, right allograft; daclizumab treated, left allograft. Radiographs obtained in the first 5 postoperative days were evaluated for degree of edema. Mean daily edema scores and curves for control and daclizumab-treated groups were compared. Differences in survival at 1, 3, 6, and 12 months after transplantation, days of mechanical ventilation, and the ratio of arterial oxygenation to inspired oxygen level at 1, 3, and 5 days after transplantation were also compared. RESULTS: Mean daily edema scores, edema curves, survival, days of mechanical ventilation, and ratio of arterial oxygenation to inspired oxygen level at 1 and 3 days after transplantation did not significantly differ between daclizumab-treated and control groups. A trend toward improved survival in the daclizumab-treated group was noted. CONCLUSION: Daclizumab had no effect on the radiographic or immediate clinical manifestations of reperfusion edema in lung transplant recipients. Additional follow-up is needed to determine if daclizumab offers any long-term benefit in terms of reduced rejection rates or survival.
Subject(s)
Antibodies, Monoclonal/therapeutic use , Immunoglobulin G/therapeutic use , Immunosuppressive Agents/therapeutic use , Lung Transplantation/adverse effects , Pulmonary Edema/drug therapy , Pulmonary Edema/etiology , Adolescent , Adult , Aged , Antibodies, Monoclonal, Humanized , Daclizumab , Humans , Middle Aged , Pulmonary Edema/diagnostic imaging , Pulmonary Edema/physiopathology , Radiography , Severity of Illness IndexABSTRACT
PURPOSE: To correlate FDG activity on PET with the expression of glucose transporter proteins Glut-1 and Glut-3 in patients with early stage non-small cell lung cancer (NSCLC). METHODS: Over a 5 year period, all patients with a PET scan and clinical stage I NSCLC underwent an immunohistochemical analysis of their tumor for Glut-1 and Glut-3 expression. The amount of FDG uptake in the primary lesion was measured by a standardized uptake ratio (SUR) and correlated with immunohistochemical results. RESULTS: Seventy-three patients with a mean age of 66 years had clinical stage I disease. The final pathologic stage showed 64 patients with stage IA/B disease, eight with stage IIA disease, and one patient with pathologic stage IIIA (T1N2) disease. Glut-1 transporter expression was significantly higher than Glut-3 (P<0.0001), and although there was some association between the SUR and Glut-1 (P=0.085) and SUR and Glut-3 (P=0.074) expression, this did not reach statistical significance. CONCLUSIONS: Glut-1 and Glut-3 transporter expression did not demonstrate a statistically significant correlation with FDG uptake in potentially resectable lung cancer. It appears that these transporters alone do not affect the variation in FDG activity in early stage NSCLC.
Subject(s)
Carcinoma, Non-Small-Cell Lung/metabolism , Fluorodeoxyglucose F18 , Lung Neoplasms/metabolism , Monosaccharide Transport Proteins/analysis , Monosaccharide Transport Proteins/metabolism , Nerve Tissue Proteins , Aged , Aged, 80 and over , Carcinoma, Non-Small-Cell Lung/diagnostic imaging , Female , Glucose Transporter Type 1 , Glucose Transporter Type 3 , Humans , Immunoenzyme Techniques , Lung/metabolism , Lung Neoplasms/diagnostic imaging , Male , Middle Aged , Radiopharmaceuticals , Tomography, Emission-ComputedABSTRACT
Multilevel diffractive optical elements are necessary for achieving high-efficiency performance. Here the diffraction efficiency of a multilevel phase-only diffractive lens is analyzed. Approximate, as well as more accurate, approaches are presented. Both plane-wave and Gaussian illumination are discussed. It is shown that for many practical cases the diffraction efficiency can be determined by only a single parameter that takes into account the spatial bandwidth product as well as the focal length of the lens and the illumination wavelength. The analysis is based on the scalar theory and the thin-element approximation. Justification for doing this is presented. The results are valid for lenses with at least F/5.
ABSTRACT
Theoretical topics encountered in engineering analysis of diffraction-free beams are addressed. These topics are the following: synthesizing a class of diffraction-free beams with noncircular transverse irradiance distributions, e.g., elliptical beams; the effect of Gaussian apodization on sidelobe control; and mode selection that allows one to synthesize a nearly diffraction-free beam with a certain depth of field. The focusing properties of Bessel-Gaussian beams will be investigated the future.
ABSTRACT
Objects that temporally vary slowly can be superresolved by the use of two synchronized moving masks such as pinholes or gratings. This approach to superresolution allows one to exceed Abbe's limit of resolution. Moreover, under coherent illumination, superresolution requires a certain approximation based on the time averaging of intensity rather than of field distribution. When extensive digital postprocessing can be incorporated into the optical system, a detector array and some postprocessing algorithms can replace the grating that is responsible for information decoding. In this way, no approximation is needed and the synchronization that is necessary when two gratings are used is simplified. Furthermore, we present two novel approaches for overcoming distortions when extensive digital postprocessing cannot be incorporated into the optical system. In the first approach, one of the gratings, in the input or at the output plane, is shifted at half the velocity of the other. In the second approach, various spectral regions are transmitted through the system's aperture to facilitate postprocessing. Experimental results are provided to demonstrate the properties of the proposed methods.
ABSTRACT
A novel, to our knowledge, configuration for the design and fabrication of zero-order computer-generated holograms in which each pixel is split into two centrosymmetric equal-sized regions is proposed and tested. In a manner similar to other approaches this configuration also permits the encoding and the reconstruction of a complex function that exhibits phase as well as amplitude variations by use of a phase-only filter. A detailed mathematical analysis is followed by evaluation of the error of the encoding approach, which is calculated and compared with the error exhibited by other approaches. Computer simulations as well as optical experiments demonstrate the capabilities of this novel configuration.
ABSTRACT
A design for a novel diffractive optical element (DOE) that can reconstruct three different intensity patterns when it is illuminated by three different wavelengths is presented. If the chosen wavelengths are red, green, and blue, full-color reconstruction capability is obtained. Reconstruction is achieved in the near field (Fresnel domain). Computer simulation results as well as experimental evidence are presented, proving the capabilities of this novel DOE design procedure.
ABSTRACT
Over the past years, positron emission tomography (PET) with fluoro-2-deoxy-D-glucose (FDG) has emerged as an important imaging modality. In the thorax, FDG-PET has been shown to differentiate benign from malignant pulmonary lesions and stage lung cancer. Preliminary studies have shown its usefulness in assessing tumor recurrence, and assisting in radiotherapy planning. FDG-PET is often more accurate than conventional imaging studies, and has been proven to be cost-effective in evaluating lung cancer patients. This review will discuss the current applications of FDG-PET as compared with conventional imaging in diagnosing, staging, and following patients with lung cancer.
Subject(s)
Fluorodeoxyglucose F18 , Lung Neoplasms/diagnostic imaging , Radiopharmaceuticals , Tomography, Emission-Computed , Combined Modality Therapy , Costs and Cost Analysis , Diagnosis, Differential , Humans , Lung Neoplasms/mortality , Lung Neoplasms/therapy , Neoplasm Recurrence, Local , Neoplasm Staging/methods , Reproducibility of Results , Survival Rate , Tomography, Emission-Computed/economics , Tomography, Emission-Computed/methods , Tomography, Emission-Computed/trendsABSTRACT
PURPOSE: To evaluate the usefulness of thoracic computed tomography (CT) in the pre-lung transplantation examination of patients with cystic fibrosis (CF). MATERIALS AND METHODS: Fifty-six patients (age range, 12-42 years) with CF were evaluated for possible lung transplantation from 1991 to 1997. Twenty-six of these patients underwent bilateral lung transplantation, 19 were awaiting transplantation at the time of the study, seven died before transplantation, and four were excluded for psychosocial concerns. Preoperative chest radiographic and CT findings were reviewed and correlated with clinical, operative, and pathology records. RESULTS: In seven patients, discrete, 1-2-cm pulmonary nodules were detected at CT. Five of these patients underwent transplantation; the nodules were found to be mucous impactions. No malignancy was found in any of the patients who underwent transplantation. Pretransplantation sputum cultures grew Aspergillus fumigatus in seven patients, none of whom had radiologic findings suggestive of Aspergillus infection. Radiographic or CT findings were suggestive of mycetoma in five cases, but no such tumors were found at transplantation. The accuracies of chest radiography and CT for the detection of pleural disease in 48 hemithoraces were 81% (n = 39) and 69% (n = 33), respectively. The radiologic findings of pleural thickening did not influence the surgical approach in any patient. CONCLUSION: Thoracic CT has little utility in the routine pre-lung transplantation examination of patients with CF.
Subject(s)
Cystic Fibrosis/diagnostic imaging , Lung Transplantation , Lung/diagnostic imaging , Tomography, X-Ray Computed , Adolescent , Adult , Aspergillosis/complications , Aspergillosis/diagnostic imaging , Child , Cystic Fibrosis/complications , Cystic Fibrosis/surgery , Female , Humans , Lung Diseases, Fungal/complications , Lung Diseases, Fungal/diagnostic imaging , Lymphatic Diseases/complications , Lymphatic Diseases/diagnostic imaging , Male , Pleura/diagnostic imaging , Pleural Diseases/complications , Pleural Diseases/diagnostic imaging , Radiography, Thoracic , Retrospective Studies , Sensitivity and SpecificityABSTRACT
PURPOSE: To describe the radiologic findings in patients with primary bronchogenic carcinoma and pulmonary metastases at presentation. MATERIALS AND METHODS: A retrospective review of patients with bronchogenic carcinoma who at presentation had pulmonary metastases. RESULTS: Fourteen (52%) men and 13 (48%) women with a mean age of 60 years were identified. Adenocarcinoma was the most common histology (70%). The number of nodules varied, although 78% of patients had greater than 50 nodules. Nodules size ranged from 2 to 30 mm, but 82% of patients had nodules less than 10 mm in diameter. Mediastinal lymphadenopathy was seen in 41% of patients, and pleural disease in 44% of patients. Only 37% had radiologic evidence of extrathoracic disease, with bone metastases (30%) being the most common. CONCLUSION: Multiple pulmonary nodules may be the presenting thoracic manifestation of primary bronchogenic carcinoma, with patterns of metastases and survival rates similar to other stage IV patients.