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The common feature of the reports by Franco et al 1 and Oliver et al 2 is the use of spiral (or volumetric) computed tomography to demonstrate features which would not be readily identifiable on conventional computed tomographic (CT) scanning. The advantages of spiral CT over conventional CT scanning are twofold: increased speed of data acquisition and volumetric (rather than slice by slice) data acquisition. The attribute of speed means that most thoracic examinations can be performed within a single breath hold and the timing of intravenous contrast administration can be precisely tailored, thus allowing reproducible enhancement of any desired part of the vasculature-for example, the pulmonary arteries in cases of suspected pulmonary embolism. Because an entire volume of data is acquired (with almost equal spatial resolution in the three axes) it is possible to reconstruct images in any plane, including threedimensional (3-D) reconstructions.3 Most examinations acquired with spiral CT scanning are presented as a series of transaxial slices, reflecting the traditional presentation of conventional CT images.In the report by Franco et al 1 the clarity with which the anomalous arteries feeding the sequestrated lung are shown on the 3-D reconstructions is striking. In the past a separate preoperative examination (either aortography or possibly magnetic resonance angiography) to identify the vascular supply would have been regarded as mandatory. Other imaging tests such as radionuclide scintigraphy or ultrasound may answer specific questions in cases of pulmonary sequestration, but the wealth of information now available from a single spiral CT examination is remarkable. Quite apart from their aesthetic appeal, the main benefit of these readily produced 3-D reconstructions is an easy appreciation of what can be complex anatomy. Nevertheless, claims for the increased diagnostic gain from these 3-D reconstructions should not be too extravagant: the anomalous vessels would be identifiable on images presented in the standard transaxial format, although without such immediacy. Furthermore, demonstration of the venous drainage into the pulmonary circulation (for the classic intralobar sequestrations) may not be so readily obtained with a single spiral CT examination. However, the ability to extract so much information from a spiral CT examination represents a substantial advance on conventional CT scanning. Spiral CT pulmonary angiography is an eVective way of demonstrating pulmonary embolism in segmental and larger arteries. 4 The basic sign of a filling defect within a well opacified pulmonary artery is straightforward enough. The case report by Oliver et al 2 highlights the fact that there may be ancillary signs of pulmonary embolism on spiral CT scanning-in this case shift of the interventricular septum-which corroborates the diagnosis and, more controversially, provides prognostic information. Shift of the interventricular septum and other signs of right ventricular dysfunction are readily demonstrated on echocardiog...

ObjectiveTo determine the prevalence of solitary pulmonary nodules (SPNs) in chest radiology studies and patient’s features associated with malignancy in a non-high-risk clinical population.MethodsPatients ≥35 years were referred for thoracic imaging in two hospitals (2010-2011). Eight radiologists determined the presence and characteristics of SPN. Selected variables were collected from radiological register and medical records. Observer agreement in the diagnosis of SPN was assessed.Results25,529 patients were included: 23,102 (90.5 %) underwent chest radiograph and 2,497 (9.5 %) a CT. The prevalence of SPN was 2.1 % (95 % CI 1.9 – 2.3) in radiographs and 17.0 % (95 % CI 15.5 – 18.5) in CT. In patients undergoing chest radiograph, detection of SPN with an irregular border was more frequent among smokers. In patients who had a CT, larger SPNs appeared to be associated with 60 years of age or over, diagnosis of a respiratory illness, or male gender. In addition, an irregular border was also more common among men.ConclusionsThe prevalence of SPNs detected by both radiograph and CT was lower than that shown in screening studies. Patient characteristics such as age, sex, respiratory disease, or smoking habit were associated with nodule characteristics that are known to be related with malignancy.Key Points• There is a lower SPN prevalence in the clinical population than in screening studies.• SPN prevalence is associated with some patient characteristics: sex, age, imaging test.• Nodule characteristics related to malignancy were associated with some patient characteristics.