The aim of this study was to determine the upper limit of the normal main pulmonary artery diameter using a modern CT system. This was measured at the level of the pulmonary artery bifurcation in 100 normal subjects using unenhanced contiguous 10 mm CT slices viewed at fixed mediastinal window settings (400/20). These normal subjects were then compared with similar unenhanced 10 mm images from 12 patients with proven pulmonary arterial hypertension (mean pulmonary artery pressure > 20 mmHg). The main pulmonary artery diameter in normal subjects was 2.72 cm (SD = 0.3). Main pulmonary artery diameter in patients with pulmonary arterial hypertension was significantly greater (p < 0.01) at 3.47 cm (SD = 0.33). A pulmonary artery diameter of 3.32 cm (main pulmonary artery diameter + 2 SD) had a 58% sensitivity and 95% specificity for the presence of pulmonary arterial hypertension. It is concluded that, using unenhanced axial 10 mm CT sections, the upper limit of normal main pulmonary artery diameter is 3.32 cm. Pulmonary arterial hypertension should be considered in patients with values above this level.

Purpose-Comparison of bone age assessed using either the "atlas matching" method of Greulich and Pyle or the "point scoring system" of Tanner and Whitehouse (TW2). Materials and methods-362 consecutive "bone age" radiographs of the left hand and distal radius performed in a large provincial teaching hospital. Data were analysed using the "method comparison" statistical technique. Ten per cent of the radiographs were re-analysed to assess intra-observer variation. Results-The 95% confidence interval for the diVerence between the two methods was 2.28 to −1.52 years. Intra-observer variation was greater for the Greulich and Pyle method than for the TW2 method (95% confidence limit, −2.46 to 2.18 v −1.41 to 1.43). Conclusion-The two methods of bone age assessment as used in clinical practice do not give equivalent estimates of bone age and we suggest that one method only (preferably the TW2) should be used when performing serial measurements on an individual patient. (Arch Dis Child 1999;81:172-173)

Previous studies have suggested that the upper limit of the thinnest portion of the pericardium is 3-4 mm using 10 mm CT slices. However, these studies suffered from small sample sizes, long data acquisition times and unconventional viewing parameters. We have measured the width of the thinnest portion of the normal pericardium using 10 mm (100 patients) and 1 mm (100 patients) high resolution CT (HRCT) slices with modern CT equipment and fixed mediastinal window settings (400/20). The pericardium was identified in all patients and was best seen anterior to the heart. The pericardium is exceptionally well seen using 1 mm HRCT slices and this may be the optimal technique for visualization of the pericardium. The upper limit of the thinnest portion of the normal pericardium (mean value + 2 SD) was 1.2 mm (10 mm CT slices) and 0.7 mm (1 mm HRCT slices). These values are substantially lower than those previously reported and in line with anatomical findings.

ObjectiveWe surveyed UK practice and compliance with the National Institute for Health and Care Excellence (NICE) ‘recent-onset chest pain’ guidance (Clinical Guideline 95, 2016) as a service quality initiative. We aimed to evaluate the diagnostic utility and efficacy of CT coronary angiography (CTCA), NICE-guided investigation compliance, invasive coronary angiography (ICA) use and revascularisation.MethodsA prospective analysis was conducted in nine UK centres between January 2018 and March 2020. The reporter decided whether the CTCA was diagnostic. Coronary artery disease was recorded with the Coronary Artery Disease–Reporting and Data System (CAD-RADS). Local electronic records and picture archiving/communication systems were used to collect data regarding functional testing, ICA and revascularisation. Duplication of coronary angiography without revascularisation was taken as a surrogate for ICA overuse.Results5293 patients (mean age, 57±12 years; body mass index, 29±6 kg/m²; 50% men) underwent CTCA, with a 96% diagnostic scan rate. 618 (12%) underwent ICA, of which 48% (298/618) did not receive revascularisation. 3886 (73%) had CAD-RADS 0–2, with 1% (35/3886) undergoing ICA, of which 94% (33/35) received ICA as a second-line test. 547 (10%) had CAD-RADS 3, with 23% (125/547) undergoing ICA, of which 88% (110/125) chose ICA as a second-line test, with 26% (33/125) leading to revascularisation. For 552 (10%) CAD-RADS 4 and 91 (2%) CAD-RADS 5 patients, ICA revascularisation rates were 64% (221/345) and 74% (46/62), respectively.ConclusionsWhile CTCA for recent-onset chest pain assessment has been shown to be a robust test, which negates the need for further investigation in three-quarters of patients, subsequent ICA overuse remains with almost half of these procedures not leading to revascularisation.