Evidence for secular trends in children's physical activity behaviour

It is not clear whether the global increase in weight problems in children is the result of excessive energy intake or decreasing energy expenditure. Methodological limitations have made it difficult to analyse. There is evidence that at least part of the problem may lie with increasing energy consumption, but it is important to examine the other side of the energy equation also. However, it is not possible to conclusively describe physical activity trends because of the absence of suitable baseline data. One solution is to summate all available evidence in as many areas of daily activities as possible and then draw tentative conclusions. This review summarises available trend data on direct representations of physical activity in a range of contexts, together with indirect measures such as sedentariness, fitness, and attitudes. The conclusions drawn are: physical activity in clearly defined contexts such as active transport, school physical education, and organised sports is declining in many countries; young people would like to be active but are often constrained by external factors such as school policy or curricula, parental rules in relation to safety and convenience, and physical environmental factors.     

Multislice CT: technical principles and future trends

Multislice scanning has substantially improved the performance of CT scanners, and thus the relation between scan duration, available scan length, and spatial resolution along the patient axis (z-axis). Near-isotropic imaging of whole organ systems is already possible with 4-slice scanners, but only with 8- to 16-slice scanners can the scan duration be shortened as well. Reconstructing overlapping thin-section data (“secondary raw data set”) provides the basis for image reconstruction in any desired plane. By using thick multiplanar reformation (MPR) techniques, image quality can be improved while keeping patient dose low. Using unfavorable scanning parameters, exposure dose can be substantially increased compared with single-slice scanning, but thick MPR and individual-dose modulation techniques can provide the basis for dose reduction. Low-kVp scanning, in particular, is useful in children and slim adults and is an excellent technique to improve image contrast in CT angiographic studies. Short spiral scans should be avoided with multislice CT since overranging (extra rotations at the beginning and end of the scan, used for data interpolation) can substantially increase patient dose. Future trends include the introduction of thinner detector rows, wider detector arrays, faster tube rotation, and area detectors than can also be used for fluoroscopy. Noise-reduction techniques and individual dose modulation will gain importance with higher isotropic resolution. Functional and perfusion imaging, as well as advanced image processing and computer-aided diagnosis programs, will add to the possibilities of the next generation of multislice CT scanners.     

Renal biopsy-related hemorrhage: frequency and comparison of CT and sonography

To evaluate the frequency of retroperitoneal hemorrhage related to renal biopsy, we prospectively assessed 182 patients (200 biopsies) using state-of-the-art CT and ultrasound. Our study revealed definite CT evidence of hemorrhage after 90.9% of biopsies. In a blinded analysis of images obtained in biopsied patients and in unbiopsied control patients the overall accuracy of CT was 93.8 versus 76.4% for ultrasound. Our data suggest that detectable hemorrhage is virtually always seen after renal biopsy and its frequency is much higher than noted in earlier studies.     

儿童CT辐射剂量:在瑞士建立一项基于年龄诊断参考水平的研究

本研究的目的是评估瑞士儿科病人在脑部、胸部、腹部CT检查中受到的辐射剂量并建立一个不同年龄组的诊断参考水平。将表格送至10个儿童CT扫描中心,表格     

CT radiation dose in children: a survey to establish age-based diagnostic reference levels in Switzerland

This work aimed at assessing the doses delivered in Switzerland to paediatric patients during computed tomography (CT) examinations of the brain, chest and abdomen, and at establishing diagnostic reference levels (DRLs) for various age groups. Forms were sent to the ten centres performing CT on children, addressing the demographics, the indication and the scanning parameters: number of series, kilovoltage, tube current, rotation time, reconstruction slice thickness and pitch, volume CT dose index (CTDI(vol)) and dose length product (DLP). Per age group, the proposed DRLs for brain, chest and abdomen are, respectively, in terms of CTDI(vol): 20, 30, 40, 60 mGy; 5, 8, 10, 12 mGy; 7, 9, 13, 16 mGy; and in terms of DLP: 270, 420, 560, 1,000 mGy cm; 110, 200, 220, 460 mGy cm; 130, 300, 380, 500 mGy cm. An optimisation process should be initiated to reduce the spread in dose recorded in this study. A major element of this process should be the use of DRLs.     

1995年—2007年全国急诊CT的使用趋势

目的确定全国医院急诊科(ED)CT使用的趋势及相关因素。材料与方法此项研究免除行业审查委员会批准。数据来自1995年—2007年国家医院门诊医疗保健调查报     

Incidental lesions found on CT colonography: their nature and frequency

CT colonography has been used to detect colonic polyps and cancers, but its effect in practice will also be influenced by the frequency with which extracolonic lesions of various types are detected. We performed a systematic review of the types of incidental lesions found on CT colonography. This is necessary to model the benefits and harms of detecting extracolonic lesions. Primary clinical studies of extracolonic findings on CT colonography were identified from electronic databases, scanning reference lists and hand searches of relevant journals and conference proceedings. A data collection proforma was used to collect information on extracolonic findings. 17 discreet studies were identified, involving 3488 patients. In total 40% of patients were recorded to have abnormalities and many had more than one abnormality. Nearly 14% of patients had further investigations and 0.8% were given immediate treatment. Extracolonic cancers were detected in 2.7% (0.9% had N0M0 cancers) and 0.9% had an aortic aneurysm. The number of extracolonic findings was high in all studies. While only a small population were judged "important", the prevalence of serious lesions outside the colon was nevertheless higher than in many other screening programs.     

Crescent sign in invasive pulmonary aspergillosis: frequency and related CT and clinical factors

PURPOSE: The aim of our study was to evaluate the frequency of the crescent sign on follow-up radiographs in patients with invasive pulmonary aspergillosis, correlated with initial CT and clinical findings. METHOD: Retrospective analysis of serial chest radiographs was performed to see the frequency of the crescent sign in 21 consecutive patients with pathologically proved invasive pulmonary aspergillosis. The appearance of the crescent sign was correlated with the pattern of parenchymal lesions on initial CT scans, the presence and duration of neutropenia, and underlying diseases. RESULTS: The crescent sign was seen in 10 of 21 patients (48%) on follow-up radiographic examinations. It was seen in patients with initially large [consolidation or mass; 9/11 (82%) patients] rather than small [nodule(s); 1/10 (10%) patients] parenchymal lesions (p = 0.002) on CT. The sign appeared in 7 of 17 (41%) patients with neutropenia 1-10 days after recovery from neutropenia. It appeared in three of four patients (75%) without neutropenia 4--8 days after treatment with amphotericin B. The appearance was not related to the duration (32 days in patients with crescent sign and 17 days without sign) of the neutropenic period (p > 0.05). The sign was seen in 8 of 15 (53%) patients with acute myelogenous leukemia and 2 of 6 (33%) patients with other diseases (p > 0.05). CONCLUSION: The crescent sign appears in about half of patients with invasive pulmonary aspergillosis with recovery from neutropenia, especially when the initial lesion is a consolidation or mass on CT scans.     

CT of adrenal tumors: frequency and clinical significance of low-attenuation lesions

The CT values of adrenal tumors were evaluated in 36 patients to determine the frequency and significance of negative CT values. Twenty-seven patients had adrenocortical adenomas (13 had primary aldosteronism, 12 had Cushing syndrome, and two had nonhyperfunctioning adenoma), one had adrenocortical carcinoma, and eight had pheochromocytomas. The CT values in primary aldosteronism (mean, 1.8 +/- 9.9 H) were lower than those in Cushing syndrome (27.6 +/- 12.0 H) and pheochromocytoma (35.9 +/- 9.8 H). Six adrenocortical adenomas had homogeneous, low CT attenuation, with CT values ranging from -20 to -0.4 H. Four of these had primary aldosteronism, one had Cushing syndrome, and one had nonhyperfunctioning adenoma. Our results suggest that adrenal tumors with homogeneous, slightly negative CT attenuation are likely to be adrenocortical adenomas, mainly primary aldosteronism and nonhyperfunctioning adenomas. This finding may be especially useful in diagnosing nonhyperfunctioning adenoma.     

Gastrointestinal wall thickening in patients with cirrhosis: frequency and patterns at contrast-enhanced CT

PURPOSE: To determine the frequency and patterns of gastrointestinal wall thickening at contrast material-enhanced computed tomography (CT) in patients with cirrhosis. MATERIALS AND METHODS: Three radiologists retrospectively assessed the contrast-enhanced abdominal CT scans of 77 patients with cirrhosis and 100 patients without cirrhosis for gastrointestinal wall thickening from the stomach through the descending colon. The frequencies of wall thickening were determined in the cirrhosis and in the control groups and were compared by using the Fisher exact test. The segmental distribution, symmetry, and enhancement pattern were evaluated in all patients with cirrhosis and gastrointestinal wall thickening. RESULTS: Gastrointestinal wall thickening was seen in 49 (64%) patients with cirrhosis and in seven (7%) control subjects (P <.005). The jejunum and ascending colon were the most common sites of gastrointestinal wall thickening; each was involved in 32 (42%; 95% CI: 30%, 53%) patients. The scans of 30 (61%; 95% CI: 47%, 75%) patients with gastrointestinal wall thickening showed multisegmental distribution. Gastrointestinal wall thickening was concentric and homogeneous in all patients with cirrhosis. CONCLUSION: Gastrointestinal wall thickening is common on contrast-enhanced abdominal CT scans in patients with cirrhosis. It frequently involves multiple segments. The jejunum and ascending colon are the most common sites of involvement.     

Intravertebral vacuum phenomenon following fractures: CT study on frequency and etiology

PURPOSE: The purpose of this work was to determine the frequency and etiology of the intravertebral vacuum phenomenon (IVP). METHOD: CT examinations of 96 vertebral fractures were evaluated for IVP. Bone mineral density (BMD) was determined in nonfractured vertebrae. For calibration purposes, densities of a standard phantom measured in 30 patients who underwent quantitative CT examinations in the same time period were used and precision was calculated. RESULTS: Eleven of 96 fractures (11.5%) showed IVP. IVP was present in 4 of 20 fractures at T12 (20%), in 4 of 23 at L1 (17.4%), and 1 IVP was found at L2-4 each. Mean +/- SD age of patients with IVP was 68.3 +/- 10.5 years and without 47.8 +/- 19.4 years (p < 0.001). Mean +/- SD density of nonaffected vertebra was 45.9 +/- 17.0 mg of hydroxyapatite/ml for patients with IVP and 139.5 +/- 62.6 mg/ml for those without IVP (p < 0.0005). An average precision of 1.2% was calculated for the density measurements over the investigated time. CONCLUSION: Following vertebral fractures, IVP on CT scans is more common than presumed and increases with age. There exists a significant inverse correlation between the BMD and the frequency of IVP.     

Effect of contraction frequency on energy expenditure and substrate utilisation during upper and lower body exercise

OBJECTIVE: To examine the effect of contraction frequency on energy expenditure and substrate utilisation during upper (UE) and lower (LE) body exercise. METHODS: Twenty four college students were recruited: 12 were tested on an arm ergometer, and the other 12 were tested on a leg ergometer. Each subject underwent three experimental trials on three separate days, and the three trials were presented in a randomised order. Each trial consisted of 10 minutes of arm cranking or leg cycling at 40, 60, or 80 rev/min, with power output being kept constant at 50 W. Steady state oxygen uptake (VO(2)) and respiratory exchange ratio (RER) were measured during each exercise. Energy expenditure was calculated from the steady state VO(2) adjusted for substrate metabolism using RER. Carbohydrate and fat oxidation were calculated from VO(2) and RER based on the assumption that protein breakdown contributes little to energy metabolism during exercise. RESULTS: Energy expenditure was greater (p<0.05) at 80 rev/min than at 40 rev/min. No difference was found between 40 and 60 rev/min and between 60 and 80 rev/min during both UE and LE. During LE, carbohydrate oxidation was also higher at 80 rev/min than at 40 rev/min, whereas no difference in fat oxidation was found among all three pedal rates. During UE, no speed related differences in either carbohydrate or fat utilisation were observed. CONCLUSIONS: Pedalling at a greater frequency helped to maximise energy expenditure during exercise using UE or LE despite an unchanging power output. Whereas contraction frequency affects energy expenditure similarly during both UE and LE, its impact on carbohydrate utilisation appears to be influenced by exercise modality or relative exercise intensity.     

Artifacts from misaligned CT in cardiac perfusion PET/CT studies: frequency, effects, and potential solutions.

CT-based attenuation correction is a widely used option in commercial PET/CT scanners. However, as a result of a nonsimultaneous acquisition and differences in temporal resolution between both modalities, a potential misregistration between the PET and CT, especially in the thorax and the upper abdomen, can be found. We observed a substantial number of apparent perfusion defects in spatial coincidence with the misregistered segments of the heart and assumed these defects were related to an incorrect attenuation correction. The purpose of this work was to assess the clinical impact of emission-transmission misalignment in myocardial perfusion imaging with PET/CT and to investigate potential solutions. METHODS: Twenty-eight coronary artery disease patients underwent PET/CT (13)NH3 rest/stress examinations. The emission-transmission misalignment was corrected by manual registration and the PET studies were reconstructed again using the realigned CT images for attenuation correction. The effects of the registration were evaluated by quantitative analysis of the local tracer uptake on a polar map basis. In addition to manual registration, 2 alternative realignment methods were evaluated: mutual information-based image registration and emission-driven correction based on the outline of the heart in the PET image. RESULTS: Manual realignment resulted in a change in the defect size of >10% of the left ventricle in 6 of 28 studies (21.4%); in 5 of the studies, this resulted in the disappearance of large apparent perfusion defects (15%-46% of the left ventricle), which were fully due to emission-transmission misregistration. Automatic image registration was unable to realign the datasets, whereas the emission-driven correction showed a good agreement with manual registration. CONCLUSION: Misregistration of PET and CT images is common in cardiac PET/CT studies and results in artifacts on the attenuation-corrected PET images, which appear to be corrected by repeating the PET reconstruction after manual realignment of the CT image data. In contrast to manual realignment, an automated emission-driven correction appears to be a promising approach.     

T1 lung cancer on CT: frequency of extrathoracic metastases

PURPOSE: To determine the frequency of extrathoracic metastases in T1 non-small-cell lung cancer. METHOD: Ninety patients with T1 lung cancer identified on CT were included. Extrathoracic metastases were evaluated at the time of initial diagnosis and during a 1-year follow-up study. The frequency of metastases was compared in terms of cell type (squamous or nonsquamous), size (<2 cm or >2 cm), and the initial CT findings of the tumor. RESULTS: Extrathoracic metastases were identified in 12 (13%) of 90 patients at the time of diagnosis and in 10 patients at the 1-year follow-up study (total, 22 of 90 [24%] patients). Tumors with ground-glass opacity on CT were associated with a significantly lower prevalence of metastases (p = 0.042). The area of ground-glass opacity was seen in 1 of 13 (85%) patients with bronchioloalveolar carcinoma and in 12 of 53 (23%) patients with adenocarcinoma other than bronchioloalveolar carcinoma (p < 0.001). There was no significant difference in the prevalence of metastases between squamous and nonsquamous cell carcinoma, between tumors smaller than 2 cm (n = 17) and larger than 2 cm in diameter (n = 73) and between tumors with or without mediastinal nodal metastases (p>0.05). CONCLUSION: Extrathoracic metastases were apparent at the initial examination in 13% of patients and at the 1-year follow-up examination in 11% of patients. The prevalence is significantly lower in tumors with ground-glass opacity.     

CT screening for lung cancer: frequency and significance of part-solid and nonsolid nodules

OBJECTIVE: In the Early Lung Cancer Action Project (ELCAP), we found not only solid but also part-solid and nonsolid nodules in patients at both baseline and repeat CT screening for lung cancer. We report the frequency and significance of part-solid and nonsolid nodules in comparison with solid nodules. MATERIALS AND METHODS: We reviewed all instances of a positive finding in patients at baseline (from one to six noncalcified nodules) and annual repeat screenings (from one to six newly detected noncalcified nodules with interim growth) to classify each of the nodules as solid, part-solid, or nonsolid. We defined a solid nodule as a nodule that completely obscures the entire lung parenchyma within it. Part-solid nodules are those having sections that are solid in this sense, and nonsolid nodules are those with no solid parts. Chi-square statistics were used to test for differences in the malignancy rates. RESULTS: Among the 233 instances of positive results at baseline screening, 44 (19%) involved a part-solid or nonsolid largest nodule (16 part-solid and 28 nonsolid). Among these 44 cases of positive findings, malignancy was diagnosed in 15 (34%) as opposed to a 7% malignancy rate for solid nodules (p = 0.000001). The malignancy rate for part-solid nodules was 63% (10/16), and the rate for nonsolid nodules was 18% (5/28). Even after standardizing for nodule size, the malignancy rate was significantly higher for part-solid nodules than for either solid ones (p = 0.004) or nonsolid ones (p = 0.03). The malignancy type in the part-solid or nonsolid nodules was predominantly bronchioloalveolar carcinoma or adenocarcinoma with bronchioloalveolar features, contrasting with other subtypes of adenocarcinoma found in the solid nodules (p = 0.0001). At annual repeat screenings, only 30 instances of positive test results have been obtained; seven of these involved part-solid or nonsolid nodules. CONCLUSION: In CT screening for lung cancer, the detected nodule commonly is either only part-solid or nonsolid, but such a nodule is more likely to be malignant than a solid one, even when nodule size is taken into account.