Capsular distance in the hip of the healthy child - normal values with sonography and MR imaging.

PURPOSE: To determine the normal values of the anterior and posterior capsular distances of the hip joint in healthy children by means of US, using MR imaging as reference, and to evaluate any possible correlation between age, length, weight and anterior capsular distance (ACD). MATERIAL AND METHODS: In our first study both hips in 14 healthy children (5-18 years old) were examined with US and MR to obtain measurements of the ACD and the posterior capsular distance (PCD). The distance from the anterior or posterior aspect of the femoral neck to the anterior or posterior aspect, respectively, of the outer limit of the capsule was determined. The distances were measured both with the hips in spontaneous external rotation of 10-15 degrees and in internal rotation of 45 degrees. In our second study, both hips in 28 healthy children (3-16 years old) were examined with US to determine the ACD. Age, length and weight were recorded. RESULTS: Study I: There was good correlation between the US and MR measurements in all positions. The ACD measured by US was significantly increased in inward rotation of the hip. Study II: There was no correlation between ACD and age, length or weight. CONCLUSION: The PCD of the hip joint can be accurately measured by US with the hip in internal rotation of 45 degrees. When compared with MR values, the ACD measured by US was dependent on the degree of rotation of the leg and increased significantly in internal rotation. Because the outer limit of the external layer of the joint capsule is sonographically more distinct, we suggest that the capsular distance should be measured from the outer limit of the joint capsule to the anterior or posterior aspect of the femoral neck. The measurement should be made perpendicular to the femoral neck, at the position where the greatest numerical value is obtained.

Pre-operative evaluation with MR in tetralogy of fallot and pulmonary atresia with ventricular septal defect.

PURPOSE: To assess whether MR imaging could replace angiography in preoperative evaluation of patients with tetralogy of Fallot and pulmonary atresia with ventricular septal defect (VSD), especially since the surgical correction was done earlier than was previously the rule. MATERIAL AND METHODS: Fourteen patients with tetralogy of Fallot (n = 10) or pulmonary atresia with VSD (n = 4), mean age 7.5 +/- 4.4 months, were evaluated with angiocardiography and MR before definitive surgical correction. RESULTS: There was good diagnostic agreement between the two modalities when evaluating right ventricular outflow obstruction; 86% for valvular and 93% for supravalvular stenosis, but the agreement was somewhat lower for the subvalvular obstruction (57%). Surgery findings, however, were in favour of MR in 5 patients concerning the subvalvular right ventricular outflow tract obstruction. MR images identified all stenoses in the right and left pulmonary arteries, but overlooked one stenosis in the main pulmonary artery. MR could evaluate patency in all palliative shunts. CONCLUSION: Even in this young age group, MR imaging offers a good alternative to angiocardiography for the pre-operative evaluation of the right ventricular outflow tract, the main pulmonary artery and the proximal right and left pulmonary arteries, before definitive surgical correction of tetralogy of Fallot and pulmonary atresia with VSD.

Synovitis in Legg-Calvé-Perthes disease. Evaluation with MR imaging in 84 hips.

PURPOSE: To evaluate, by means of MR imaging, the degree and persistence of synovitis in the hip joint in Legg-Calvé-Perthes disease and to correlate the degree of synovitis with the degree of epiphyseal necrosis. MATERIAL AND METHODS: A total of 170 MR images in 72 patients (84 hips) were examined. The T2-weighted MR images were taken in the coronal plane in order to evaluate the degree of synovitis in the hip joint. RESULTS: MR revealed synovitis in all cases in the early phase of the disease. In Catterall group II, synovitis was discreet to moderate for up to 6 months after diagnosis. Hips with more severe necrosis, Catterall groups III and IV, had moderate or intense degrees of synovitis. There was a correlation between the degree of synovitis and the lateral pillar classification according to HERRING et al. Also, there was a good correlation between the extent of signal changes in the epiphysis on MR imaging and the degree of synovitis. There was no difference when signal changes were evaluated on T1- or T2-weighted images. Signs of synovitis could be seen for up to 30 months after diagnosis in Catterall group I hips, and in Catterall groups II and III for up to 36 months, and in 2 cases even longer. Some Catterall group IV hips had discreet or mild synovitis for 60 months or more, after diagnosis. CONCLUSION: The degree of synovitis on MR imaging correlates to the extent of epiphyseal necrosis seen on radiographs or MR imaging as well as to the lateral pillar classification, i.e. to a poor clinical outcome. In Catterall group IV hips, synovitis can even persist for up to 60 months after diagnosis.

Epiphyseal bone-marrow abnormalities and restitution in Legg-Calvé-Perthes disease. Evaluation by MR imaging in 86 cases.

PURPOSE: By means of MR imaging, to determine signal abnormalities in the femoral epiphysis; to determine their location, extent and restitution over time; and to correlate these findings to the Catterall radiological classification. MATERIAL AND METHODS: A total of 247 MR images in 86 patients (101 hips) with Legg-Calvé-Perthes disease were examined. The MR images were taken in the coronal plane, and the images through the center of the femoral head were used for this study. RESULTS: T1-weighted images proved as good as T2-weighted images for the MR evaluation of the extent of the necrosis. In almost every case, the central-cranial part of the epiphysis showed a low initial signal. In Catterall group I, the medial part was never involved. In Catterall III and IV, almost the entire epiphysis showed signal changes. In the period 3-6 years after diagnosis, we still found signal changes in the epiphysis in some hips but there was no correlation with the Catterall classification. After 6 years, the epiphysis showed normal signal intensity in MR imaging. In T1-weighted images, Gd-enhancement occurred in the peripheral regions in the early stages of the disease. The central part of the epiphysis became more enhanced over time and peaked in the period 1-3 years after diagnosis. CONCLUSION: MR is a valuable modality for monitoring changes in the femoral epiphysis. We propose a new classification of the extent and pattern of epiphyseal bone-marrow abnormalities based on the 4 zones most commonly observed in MR imaging.

Magnetic resonance imaging and early remodeling of the femoral head after femoral varus osteotomy in Legg-Calvé-Perthes disease.

We studied 21 children with Legg-Calvé-Perthes Disease with a prognostically poor development, including lateralization, poor containment, anterolateral flattering, and deformation of the femoral head, as evaluated on serial magnetic resonance (MR) imaging. These children were treated with proximal femoral varus derotation osteotomy. The sphericity of the cartilaginous and bony femoral epiphysis was evaluated postoperatively on serial radiography and MR imaging. There was an early postoperative continuous spherical remodeling over a follow-up period of 3.0 years (1.0-5.1; SD, 1.3).

Metaphyseal histology and magnetic resonance imaging in Legg-Calvé-Perthes disease.

Cylindrical biopsy specimens from the proximal femoral metaphysis were obtained in conjunction with surgery in 22 patients with Legg-Calvé-Perthes disease. The histopathological examination revealed fat necrosis, vascular proliferation, and focal fibrosis indicating previous episodes of ischemia. There was no correlation between the histopathological findings and the corresponding magnetic resonance images.

Spatial resolution requirements in digital radiography of scaphoid fractures. An ROC analysis.

PURPOSE: To investigate the spatial resolution requirements in digital radiography of scaphoid fractures. MATERIAL AND METHODS: Included in the study were 60 scaphoid radiographs with and 60 without fractures of the scaphoid bone. The film-screen images were digitized using pixel sizes of 115, 170, and 340 microns along with 170 microns with a 10:1 wavelet compression. The digital images were displayed on a 1280 x 1024 x 8 bits monitor, and 5 observers evaluated the images in 5 randomized sessions. The results for each pixel size were then compared to the film-screen images by ROC analysis. RESULTS: The mean area under the ROC curves was larger for the film-screen images than for the digital images at all resolutions. However, this difference was not significant when the areas under the ROC curves for the film-screen images were compared to the digital images of 115, 170, and 170 microns with 10:1 compression. There was a significant difference for the 340-microns pixel size in favour of the film-screen images. The mean ROC curves for the digital images were very similar for the 115 and 170 microns pixel sizes, although slightly better for 115 microns. At 170 microns, the compression seemed to have a relatively small negative effect on the diagnostic performance; the deterioration was greater when the pixel size was increased to 340 microns. There was no obvious correlation between diagnostic performance and the experience of the observers in using work-stations. CONCLUSIONS: The pixel size of 170 microns is adequate for the detection of subtle fractures, even after wavelet compression by a ratio of 10:1.

Complex congenital heart malformation evaluated with MR imaging at 0.3 T.

The aim of this study was to evaluate the efficiency of MR imaging at 0.3 T as the single modality in diagnosing complex congenital heart disease (CHD). Films from 45 cases were reviewed in two stages by four specialists and one fellow in pediatric radiology, who were unfamiliar with the patients. First a general review of CHD diagnosis was made, then a detailed study of anomalous venous return was performed. Regarding the general diagnosis of cardiovascular anomalies the results were good, with sensitivity of 80%, specificity of 96%, a positive predictive value of 88%, a negative predictive value of 93% and accuracy of 92%. As expected, the less experienced reviewer had somewhat lower figures. As for detailed evaluation of the anomalous veins, the diagnostic results were again good (sensitivity 85%), although less so when also the connection sites of the anomalous veins were considered (sensitivity 79%). The specificity of the findings was high at 97%. MR imaging at 0.3 T is valuable in the diagnosis of complex CHD, especially for anomalous vessels and their connections.

Phantom study of chest radiography with storage phosphor, selenium, and film-screen systems.

PURPOSE: Chest radiographs from 3 digital systems--2 based on luminescent phosphors and one on selenium--and a conventional film-screen system were evaluated and compared. MATERIAL AND METHODS: Computed radiography (CR) has for the past years been dominated by a single manufacturer, but now several systems have been marketed. Using a chest phantom and, as test objects, 2 simulated tumours for the lung and mediastinum, respectively, and one object simulating pulmonary lines, a total of 400 exposures were made, 100 on each system. The test objects were placed randomly with a ratio of presence/absence of each object of about 50. Six radiologists participated, 2 residents and 4 staff members. A receiver operating characteristics (ROC) analysis was performed with construction of curves, and the difference between the curves was estimated with a 2-tailed paired t-test. RESULTS AND CONCLUSION: The selenium-based system performed significantly better for pulmonary line detection than all the other systems, and better than one storage phosphor system for the lung "tumour" (p < 0.05), while one storage phosphor system was slightly better than the other in diagnosing all 3 test objects. The score for the film-screen system was only average.

Percutaneous translumbar central venous catheter in infants and small children.

Vascular occlusion is a common clinical problem in children dependent on prolonged vascular access. As an alternative to conventional central venous catheter placement we report our experience of four children receiving translumbar inferior vena cava catheter on 12 different occasions. All catheter placements were successful. No procedure-related complications occurred. The median catheter patency was 4.8 months (range 1-10 months). The translumbar route for central venous access is safe and reliable and should be considered when prolonged use is anticipated in infants and small children.

Effect of bile obstruction on liver regeneration following major hepatectomy: an experimental study in the rat.

The regeneration of the liver following resection is regulated by a variety of factors and it might be expected that jaundice influences the process. We therefore evaluated the regenerative response to major hepatectomy in bile-obstructed rats. Two weeks after ligation of the common bile duct, a standardized 77% hepatectomy was undertaken. The jaundiced animals showed an augmented liver regeneration compared to nonjaundiced individuals (p < 0.01). However, blood clearance of radiolabelled Escherichia coli bacteria was impaired (p < 0.01) in animals with bile obstruction at 7 days after the hepatectomy, accompanied by reduced bacterial uptake in the liver as a sign of impaired reticuloendothelial system function.

Sonography and intracapsular pressure in Perthes' disease. 39 children examined 2-36 months after onset.

39 children with Legg-Calvé-Perthes Disease (LCPD) and with a radiographically unsatisfactory development were examined with sonography regarding synovitis and with intracapsular pressure recording and aspiration performed 15 (2-36) months after the onset of symptoms. The mean anterior sonographic capsular distension was 3.0 (1.0-7.0) mm greater than that of the contralateral, asymptomatic hip. The mean intracapsular pressure was 4.5 (0-11.5) kPa with the hips in extension and neutral rotation, 9.7 (1.3-27.3) kPa with the hips in extension and inward rotation and 0.9 (-0.8-4.7) kPa in 45 degrees of flexion. We conclude that these children have synovitis as diagnosed sonographically. This synovitis is probably symptomatically and prognostically important in LCPD due to increased intracapsular pressure, with pain, a decreased range of motion and, potential joint contracture.

Femoral head shape in Legg-Calvé-Perthes disease. Correlation between conventional radiography, arthrography and MR imaging.

Twenty-three children with Legg-Calvé-Perthes disease were examined to determine the femoral head shape. We evaluated and correlated conventional radiography, arthrography and MR imaging. In the a.p. view, measurements were obtained from the center of the femoral head along the bony or cartilaginous outline at 30 degrees intervals. Maximum flattening of the cartilaginous outline appeared laterally, 60 degrees from the center of the baseline of the epiphyseal index and the caput index. Maximum flattening of the bony outline was found at 75 degrees. Arthrography and MR imaging gave the same information about the shape of the femoral head cartilage. The bony femoral head shape on conventional radiographs in the a.p. view did not reflect the cartilage shape obtained by MR and arthrography.

Evaluation of the image quality of ink-jet printed paper copies of digital chest radiographs as compared with film: a receiver operating characteristic study.

Paper copies of digital radiographs printed with the continuous ink-jet technique have proved to be of a high enough quality for demonstration purposes. We present a study on the image quality of ink-jet printed paper copies of digital chest radiographs, based on receiver operating characteristic (ROC) analysis. Eighty-three digital radiographs of a chest phantom with simulated tumors in the mediastinum and right lung, derived from a computed radiography (CR) system were presented in two series of hard copies as ink-jet printed paper copies and as laser recorded film. The images, with a matrix of 1,760 x 2,140 pixels, were printed with a spatial resolution of 10 pixels/mm in the CR film recorder as well as in the ink-jet printer. On film, every image was recorded in two versions, one optimized for the mediastinum and one for the lungs. On paper, only one image was printed; this constituted an effort to optimize both the mediastinum and the lungs. The ink-jet printed images, printed on a matt coated paper, were viewed as on-sight images with reflected light. The examinations were reviewed by six radiologists, and ROC curves were constructed. No significant difference was found between the performance of film and that of ink-jet paper prints. Because the cost for a paper copy is only a tenth of that of film, remarkable cost reductions can be achieved by using the ink jet technique instead. Our results show that further quality studies of ink-jet printed images are worthwhile.

Digital luminescence radiography using a chest phantom. Comparison between radiographs displayed on monitor at a workstation and at a personal.

With the introduction of picture and archiving communicating systems an alternative image display for the wards might be a personal computer (PC). The intention with this study was to evaluate the diagnostic image quality of the monitor of a PC compared to that of a workstation. Eighty-five digital radiographs of a chest phantom with simulated tumors in the mediastinum and right lung were saved on optical discs. The examination were reviewed by 4 radiologists on a monitor at a workstation and at a PC, and receiver operating characteristic (ROC) curves were constructed. No significant difference was found between performance of the PC and the workstation.

Liver regeneration following 68% partial orthotopic liver transplantation in the rat.

Liver regeneration following transplantation in 'small for size' conditions is not fully understood. We therefore evaluated the regenerative response of transplanted partial liver grafts in outbred rats without the use of immunosuppression and compared it to liver regeneration following resection. The transplanted livers showed enhanced regeneration compared to controls. We suggest that this is caused by activation of the immune system.

Digital luminescence radiography using a chest phantom. Comparison between radiographs displayed on monitor and hard-copy.

Ninety-eight digital radiographs of a chest phantom with simulated tumors in the mediastinum and left lung and a pneumothorax-simulation in the right hemithorax were compared with the corresponding examinations saved on optical disk and viewed on a 1,000-line monitor. The examinations were reviewed by 7 radiologists with different experience, and receiver operating characteristic (ROC) curves were constructed. There was no significant difference between the hard-copy and the monitor results. A significant interobserver difference was seen only with the low attenuating 6 mm "tumor" and then only between the observer with the highest and the one with the lowest scores.

Efficacy of inverted digital luminescence radiography in evaluating chest neoplasms.

Inverted (positive) digital chest radiographs of patients with lung tumors were compared with commonly used (negative) digital images, consisting of one simulated normal and one contrast enhanced image. The first part of the material consisted of 80 patients of whom 40 had tumors and 40 were normal. Five radiologists with different experience reviewed the examinations. From their answers, ROC curves were constructed. The second part of the material consisted of 100 chest phantom examinations with a simulated tumor in the mediastinum (45 examinations) and/or the left lung (46 examinations). In 31 exposures there was no abnormality. These were reviewed by 3 observers and performed as an ROC study as well. There was no statistical difference between the different types of images or between the observers in the 2 studies.

Digital luminescence radiography in interstitial lung disease. A receiver operating characteristics (ROC) analysis.

The subtle changes often found in interstitial lung disease can be difficult to evaluate at conventional radiography. In order to define the information obtained with digital radiography, it is particularly important to find out to what extent interstitial lung disease can be observed with this technique. Ninety-one patients, 56 with interstitial lung disease and 35 with normal lungs, were examined both with a digital system and with conventional film-screen technique. The examinations were reviewed independently by 4 radiologists with different experience and receiver operating characteristics (ROC) curves were constructed. The 2 systems were equal in diagnostic performance with no statistic difference between the conventional radiographs, the 2 digital images reviewed together or the 2 digital images reviewed separately. There was a significant difference between the 2 observers with the highest and the one with the lowest score only in the review of digital unsharp mask images, but otherwise no differences statistically. A lower number of false negatives and a higher number of false positives were seen with the digital unsharp mask image, producing a higher sensitivity and lower specificity.