Indication-based national diagnostic reference levels for paediatric CT: a new approach with proposed values.

Indication-based national diagnostic reference levels (DRLs) for a few most common paediatric computed tomography (CT) examinations are proposed. Patient dose data (CTDI vol and dose length product) were collected for over 1000 patients in 4 university hospitals with best experiences in paediatric CT. Four indications for chest CT and two for abdomen (abdomen + pelvis), chest + abdomen and head CT were considered. The DRLs for the body examinations are proposed as exponential DRL-curves, where CTDI vol and dose length product are presented as a function of patient weight. The same DRL curve applies to all the indications studied. The basic 75 % level curve is supplemented by 50 % level curve to enable considerations on varying levels of technology. For head CT, DRLs are proposed for a few age groups (1, 1-5, 5-10 and 10-15 y), separately for routine CT and CT for ventricular size. The proposed DRLs are generally lower than the few published DRLs in other countries.

Patient doses in paediatric CT: feasibility of setting diagnostic reference levels.

Despite the fact that doses to paediatric patients from computed tomography (CT) examinations are of special concern, only few data or studies for setting of paediatric diagnostic reference levels (DRLs) have been published. In this study, doses to children were estimated from chest and head CT, in order to study the feasibility of DRLs for these examinations. It is shown that for the DRLs, patient dose data from different CT scanners should be collected in age or weight groups, possibly for different indications. For practical reasons, the DRLs for paediatric chest CT should be given as a continuous DRL curve as a function of patient weight. For paediatric head CT, DRLs for a few age groups could be given. The users of the DRLs should be aware of the calibration phantom applied in the console calibration for different paediatric scanning protocols. The feasibility of DRLs should be re-evaluated every 2-3 y.

Hereditary isolated metatarsophalangeal arthritis.

OBJECTIVE: To describe a family with 13 members in four generations affected by early-onset isolated painful arthritis limited to the first metatarsophalangeal (MTP) joint but without evidence of generalized joint disease at follow-up. METHODS: A complete family pedigree was constructed and radiographs from the affected family members and their offspring were taken. Laboratory tests including serum measurements of C-reactive protein (CRP), urate, and rheumatoid factor (RF) were performed to exclude gout and rheumatoid arthritis from the diagnosis. RESULTS: The age at onset of first MTP joint symptoms varied from 12 to 51 years. Both females and males were affected in the four successive generations, including male-to-male transmission as well as maternal inheritance. The affected patients were often treated surgically with good pain-relieving results. CONCLUSION: To our knowledge, this is the first report of early-onset isolated foot metatarsal arthritis with apparent autosomal dominant inheritance.

CT lung densitometry in assessing intralobular air content. An experimental and clinical study.

PURPOSE: To introduce a parameter called "intralobular air content percentage" to replace the CT number of the lung and to establish a proper protocol for its assessment. MATERIAL AND METHODS: We calibrated the HU (Hounsfield unit) scale for low densities with foam and evaluated the influence of certain acquisition and reconstruction parameters on the accuracy of CT densitometry of the lungs. The reproducibility of the results obtained in human experiments and the intralobular air content percentage of normal and diseased lung tissue were assessed. RESULTS: Air content could be reliably derived from the calibrated CT number of an area within a secondary lobulus. The mean intralobular air content of normal lungs varied from 77.8% to 88.0% in full inspiration. Helical or axial recording with a 10-mm slice thickness, a standard or soft algorithm and high tube currents and voltage settings, was suitable for the measurements. CONCLUSION: Before absolute lung density measurements (as a HU number or an air content percentage), the CT equipment has to be calibrated for low densities. The intralobular air content percentages of cooperative patients were reliably reproducible.

Helical CT in evaluation of the bronchial tree.

PURPOSE: To establish a protocol for and to assess the value of helical CT in the imaging of the bronchial tree. MATERIAL AND METHODS: Noncontrast helical CT was performed in 30 patients undergoing fiberoptic bronchoscopy for different reasons. Different protocols were compared; they included overlapping 10 mm, 5 mm, or 3 mm slices and non-tilted, cephalad or caudad tilted images. Ordinary cross-sectional and multiplanar 2D reformats were applied for visualization of the bronchial branches. The effect of increasing the helical pitch was tested in one patient. RESULTS: A total of 92.1-100% of the segmental bronchi present in the helical acquisitions were identified by the different protocols. The collimation had no significant impact on the identification of the bronchial branches, but utilization of 3-mm overlapping slices made it easier to distinguish the nearby branches and provided better longitudinal visualization of the bronchi in 2D reformats. The tilted scans illustrated the disadvantage of not covering all segmental bronchi in one breath-hold. An increase of the pitch from 1 to 1.5 did not cause noticeable blurring of the images. CT and bronchoscopic findings correlated well in the area accessible to bronchoscopy, but CT detected 5 additional pathological lesions (including 2 cancers) in the peripheral lung. CONCLUSION: Helical CT supplemented with bronchography-like 2D reformats provides an effective method complementary to bronchoscopy in the examination of the bronchial tree.