Peter Hochbergs

Collateral flow in coarctation of the aorta with magnetic resonance velocity mapping: Correlation to morphological imaging of collateral vessels

To correlate quantification of collateral flow in aortic coarctation with the morphological visualization of the collateral vessels and to compare different approaches to measurement of collateral flow.

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 pre-operative 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.

Late coronary complications after arterial switch operation and their treatment

Objectives: To report the late coronary complications and their treatment after arterial switch operation (ASO). Background: Asymptomatic patients after ASO may have coronary ostial stenosis or obstruction. Methods: Since 1980, 279 patients were operated with ASO. At the time of preparing this article, selective follow‐up coronary angiograms were done on 81 patients. Results: Coronary stenosis was found in six patients. A 6‐year‐old patient with left coronary artery (LCA) ostial stenosis and a 9‐year‐old patient with conus branch occlusion had good collaterals without a need for further treatment. One patient with LCA obstruction, myocardial infarction, and left ventricular failure was operated with osteoplasty at age of 16 years. In three essentially asymptomatic patients, stenting of LCA ostium stenosis was done: in two of them with drug‐eluting stents at 9 and 10 years of age and in one with bare‐metal stent at 18 years of age. One of these patients was earlier treated with balloon dilatation at 5 years of age which caused intimal dissection. Conclusions: Asymptomatic patients with an uneventful course after ASO may have coronary obstruction. This necessitates follow‐up coronary evaluation in all patients. Stenting of the coronary arteries is an option for treatment.

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.

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 phatom with simulated tumors in the mediastinum and right lund, 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 1,760×2,140 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 exdaminations 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.

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.

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 using a chest phantom : comparison between radiographs displayed on monitor at a workstation and at a personal computer

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 examinations 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.

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° and in internal rotation of 45°. 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°. 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.

Changes in blood volume shunting in patients with atrial septal defects: assessment of heart function with cardiovascular magnetic resonance during dobutamine stress.

Abstract Background The purpose of this study was to determine the effect of stress on left-to-right shunting in patients with atrial septal defect (ASD) and to investigate if the degree of shunting, cardiac output (CO), and right ventricular (RV) volumes are related to exercise capacity. Methods Twenty-six patients with a secundum ASD and 16 healthy volunteers were studied with rest/stress cardiac magnetic resonance using 20 µg/kg/min dobutamine and 0.25–0.75 mg atropine to quantify CO, pulmonary to systemic flow ratio (QP/QS), and left ventricular (LV) and RV volumes. Peak oxygen uptake (VO2peak) was determined on ergospirometry. Results In patients with ASD the QP/QS decreased from 2.0 ± 0.2 at rest to 1.5 ± 0.1 (P < 0.001) during dobutamine stress (n = 20) and shunt volume per heartbeat decreased from 70 ± 9 to 38 ± 9 mL (P < 0.001). However, absolute shunt volume per minute was unchanged (5.1 ± 0.8 vs. 4.5 ± 1.0 L/min, P = 0.32) explained by a higher increase in systemic CO during stress (90 ± 11%) compared with pulmonary CO (43 ± 7%, P < 0.001). In ASD patients, VO2peak correlated with aortic CO during stress (r = 0.77) and QP/QS at rest (r = −0.48) but not during stress (P = 0.09). VO2peak did not correlate with RV volumes in patients. Conclusion Pulmonary to systemic flow ratio and shunt volume per heartbeat decrease during stress in ASD patients. This may be explained by an enhanced LV diastolic function during stress and may have implications to detect disturbances in LV compliance in ASD patients. A high systemic CO during stress is a strong predictor of exercise capacity.