ABSTRACT
The purpose of this work is to develop patient-specific models for automatically detecting lung nodules in computed tomography (CT) images. It is motivated by significant developments in CT scanner technology and the burden that lung cancer screening and surveillance imposes on radiologists. We propose a new method that uses a patient's baseline image data to assist in the segmentation of subsequent images so that changes in size and/or shape of nodules can be measured automatically. The system uses a generic, a priori model to detect candidate nodules on the baseline scan of a previously unseen patient. A user then confirms or rejects nodule candidates to establish baseline results. For analysis of follow-up scans of that particular patient, a patient-specific model is derived from these baseline results. This model describes expected features (location, volume and shape) of previously segmented nodules so that the system can relocalize them automatically on follow-up. On the baseline scans of 17 subjects, a radiologist identified a total of 36 nodules, of which 31 (86%) were detected automatically by the system with an average of 11 false positives (FPs) per case. In follow-up scans 27 of the 31 nodules were still present and, using patient-specific models, 22 (81%) were correctly relocalized by the system. The system automatically detected 16 out of a possible 20 (80%) of new nodules on follow-up scans with ten FPs per case.
Subject(s)
Lung Neoplasms/diagnostic imaging , Models, Biological , Radiographic Image Interpretation, Computer-Assisted/methods , Radiography, Thoracic/methods , Tomography, X-Ray Computed/methods , Automation , False Negative Reactions , Follow-Up Studies , Humans , Retrospective Studies , Sensitivity and SpecificityABSTRACT
A ureteric ring is a smooth, concentric ring-like narrowing occurring in the upper third of the ureter. It is nonobstructive and may be transient and bilateral. There is a slight female preponderance. They are seen in all age groups and are common in the neonate together with transient changes. A ureteric ring has a characteristic appearance and is believed to result from contraction of circular muscle.
Subject(s)
Ureter/abnormalities , Adult , Aged , Child, Preschool , Female , Humans , Male , Middle Aged , Muscle Contraction , Retrospective Studies , Ureter/diagnostic imaging , UrographyABSTRACT
Balloon occlusion hepatic venography using carbon dioxide (CO2) is proposed as a safer yet simpler alternative to wedged catheter techniques that have caused hepatic lacerations during the transjugular intrahepatic portosystemic shunt (TIPS) procedure. The image quality of CO2 wedged catheter and balloon occlusion venograms was comparable in our small series, with no venographic-related complications occurring in the balloon occlusion group.
