Ergonomics of digital imaging.

There has been an increase in the use of digital imaging in recent years and radiologists have almost universally accepted the use of computers in their day-to-day work. Completely filmless radiology departments, with all reporting being done on visual display terminals and picture archiving and communications systems (PACS) around the department, are already a reality in many places in the UK and other parts of the world. There is a constant need of computers for literature searches on the web, e-mails, communication and preparing lectures and presentations. With this explosive increase in the use of computers in the hospital, it is imperative that the use of computer monitor screens for medical use is optimized in order to avoid eyestrain and fatigue. This is especially important as tired eyes and brains may be more likely to commit errors. We have reviewed the current literature to elaborate a few useful measures that can be taken to minimize the effect of excessive computer use in a soft-copy radiology reporting area on the eyes and the musculoskeletal system. We recommend that optimal placement of computer monitors with user-friendly PACS terminal interfaces will ensure greater acceptability and improve reporting efficiency and accuracy. Good work practices to ensure reduction of reporting errors are highlighted.

Chest radiograph interpretation by medical students.

AIM: To assess the ability of final year medical students to interpret conventional chest radiographs. MATERIALS AND METHODS: Ten conventional chest radiographs were selected from a teaching hospital radiology department library that were good radiological examples of common conditions. All were conditions that a medical student should be expected to recognize by the end of their training. One normal radiograph was included. The radiographs were shown to 52 final year medical students who were asked to describe their findings. RESULTS: The median score achieved was 12.5 out of 20 (range 6-18). There was no difference between the median scores of male and female students (12.5 and 12.3, respectively, p=0.82) but male students were more likely to be certain of their answers than female students (median certainty scores 23.0 and 14.0, respectively). The overall degree of certainty was low. On no radiograph were more than 25% of students definite about their answer. Students had received little formal radiology teaching (2-42 h, median 21) and few expressed an interest in radiology as a career. Only two (3.8%) students thought they were good at interpreting chest radiographs, 17 (32.7%) thought they were bad or awful. CONCLUSION: Medical students reaching the end of their training do not perform well at interpreting simple chest radiographs. They lack confidence and have received little formal radiological tuition. Perhaps as a result, few are interested in radiology as a career, which is a matter for concern in view of the current shortage of radiologists in the UK.

MRI of the teeth.

The teeth and periapical structures were demonstrated on MRI using an open MRI system. There was good visualization of normal structures including crowns of teeth, pulp chambers and the neurovascular bundle of the inferior dental nerve. Dental and periapical pathology was shown.

Adverse effect of previous bronchial asthma on disability in chronic airflow obstruction.

The average distance covered when attempting to hurry on the level for 12 min (12 min walking distance) is linearly correlated to forced expiratory volume in 1 s in healthy middle-aged individuals and patients with chronic airflow obstruction. Patients with current or past asthma, with or without chronic bronchitis and emphysema, walk more slowly than those with chronic obstructive pulmonary disease for a similar degree of airflow obstruction. A previous history of asthma may be a factor in the limitation of effort caused by chronic respiratory disease.

Ethical issues in teleradiology.

Teleradiology is the electronic transmission of radiographic images from one geographic location to another for the purposes of diagnosis and/or consultation. It raises interesting ethical and practical issues which have received relatively little attention in the radiology or ethics literature to date. These include confidentiality, data security and technological reliability, consent, competence, interprofessional and professional-patient relationships, and the organization of medical services. This paper reviews these issues, discussing how far these are new concerns in radiological practice, and makes suggestions for minimum ethical and professional standards for teleradiological practice.

The influence of clinical information on the reporting of CT by radiologists.

The aim of the study was to determine whether clinical information alters the CT report. This prospective blinded study consisted of 50 consecutive patients who attended a Department of Radiology for CT. Each study was interpreted by two of three consultant radiologists, before and after knowledge of the clinical information. 19 reports were changed after clinical information was known. Clinical follow-up was available in 15 cases. In ten cases the reports were more accurate after clinical information and in five cases the reports were less accurate. In three of the five cases where accuracy was reduced, the clinical information was incorrect. It was concluded that clinical information affects the CT report. If the information is accurate it has a beneficial effect; if it is inaccurate it has a detrimental effect. The more complex the investigation, the more important the clinical information. There was a correlation between readers regarding the influence of clinical information. Correct clinical information therefore improves the radiology report. It is the responsibility of the clinician to provide this information in an accurate and legible form.

Magnetic resonance imaging and magnetic resonance angiography in long term survivors of acute lymphoblastic leukemia treated with cranial irradiation.

BACKGROUND: Successful treatment of acute lymphoblastic leukemia (ALL) has resulted in an increasing number of patients whose disease is cured. This treatment includes cranial irradiation as prophylaxis against central nervous system relapse. The late effects of irradiation are well documented, but their incidence is unknown. The authors investigated the late effects of this treatment modality further by scanning 35 long term survivors of ALL who received cranial irradiation. METHODS: Thirty-five survivors of ALL with no known complication of treatment were included in this study. They were examined with magnetic resonance imaging (MRI) of the brain and magnetic resonance angiography (MRA) of the circle of Willis. A control group of 24 patients who were cured of other childhood malignancies without exposure to cranial irradiation also were scanned. RESULTS: Fifteen of 35 (43%) abnormalities were found in the study group versus 4/24 (17%) in the control group. Excluding minor atrophic changes that are known to be produced by irradiation and chemotherapy, there were 9/35 (26%) abnormalities in the study group and 1/24 (4%) in the control group (P < 0.05). These abnormalities included three tumors, a meningioma, a paranasal sinus rhabdomyosarcoma, and an anaplastic astrocytoma. In addition, there were two cases of large vessel vasculopathy, two small cystic infarcts, one diffuse white matter abnormality, and one cryptic vascular malformation. The abnormal control patient had a cerebellar infarct. CONCLUSION: Complications of cranial irradiation in the treatment of ALL appear to be more frequent than currently are appreciated. That these complications include tumors that are potentially treatable suggests that screening may be valuable for these patients.

Audit of the value of double reading magnetic resonance imaging films.

100 consecutive magnetic resonance imaging (MRI) examinations were reviewed independently by two radiologists. Patients were selected so that the anatomical areas of clinical interest coincided with the special interests of the reviewers. The reviewers were both consultant radiologists, one with 3 years' and the other with 6 years' experience of MRI. Hard copy images from the MRI examinations were reported independently by both reviewers. Of the 100 MRI examinations, there was full concordance of opinion in 61/100. Of the remaining 39 cases, four (10%) were considered "minor unrelated" differences, 12 (31%) "minor related" differences and 23 (59%) "major related" differences resulting in a significant change in patient management.

Demonstration of supernumerary tracheal bronchus by computed tomographic scanning and magnetic resonance imaging.

A bronchus arising directly from the trachea is an infrequent congenital anomaly which usually represents the displaced origin of a normal bronchus. Rarely, a true supernumerary tracheal bronchus occurs supplying an associated tracheal lobe. The case is described of a patient in whom a supernumerary tracheal bronchus and tracheal lobe was demonstrated by computed tomographic scanning and magnetic resonance imaging.

Quantification of melanin and iron content in uveal malignant melanomas and correlation with magnetic resonance image.

Eleven patients with uveal malignant melanomas (MM) were studied by magnetic resonance (MR) imaging before enucleation. The MR appearances varied, but often were different from those previously reported to be characteristic of these tumours. Using an image analyser to assess quantitatively the melanin and iron content of each tumour, a wide range of tumour melanin concentrations was found, but universally low tumour iron concentrations. These values were compared with MR appearances that were quantified and expressed as contrast to noise ratios. The correlation between T1 and T2 shortening and increasing melanin content did not reach statistical significance. There was no correlation between MR appearances and iron content. The theories postulated to explain the diverse MR appearances of uveal MMs are discussed and variations in tumour melanin content and differences in scanner strengths are suggested as the most likely explanations.

An image processing technique for the identification of contact pixels applied to x-ray CT images of implanted hip prostheses.

Uncemented prosthetic joint implants used in orthopaedic surgery are usually coated with a porous surface to encourage bone ingrowth. Better contact between the endosteal bone and the porous surface improves ingrowth, and such contact may be increased if the joint further subsides into position in the first weeks following implantation. An image processing technique has been developed as part of a study undertaken to determine the effect of early subsidence on endosteal contact. The method provides a measure of the degree of contact between the surfaces from transverse x-ray CT images, but is suitable for application to any image with a similar intensity distribution.

Review of the use of MRI in soft tissue lesions.

The MR images of 34 patients with soft tissue lesions were retrospectively evaluated to assess the accuracy of the technique in distinguishing benign from malignant lesions, and to assess the usefulness of various criteria in making this distinction. The overall sensitivity for the detection of malignancy was 75% with a specificity of 94%. Size of lesion was found to be a good criterion in predicting malignancy, lesion margin and signal intensity were less useful. The tissue type was determined in a few instances where signal characteristics were typical, notably lipomas and neural tumours, but this was not reliable and in most lesions the tissue of origin cannot be determined on MR imaging and biopsy is necessary.

Fat-suppression magnetic resonance imaging in the preoperative localization of parathyroid adenomas.

Prospective localization of parathyroid adenomas was attempted in 16 patients with hyperparathyroidism prior to surgery. All patients had magnetic resonance imaging (MRI) using T1-weighted spin-echo (SE) sequences and a fat-suppression sequence, the short-tau inversion recovery (STIR) sequence. Correlation with the results of surgery yielded an overall sensitivity of 71% and a specificity of 94%. Performance was good in patients with previous surgery and with ectopic tumours. We believe that fat-suppression MRI is a valuable technique in the preoperative localization of parathyroid adenomas in patients with hyperparathyroidism.

Appearances of choroidal osteomas with diagnostic imaging.

The diagnostic imaging appearances of three choroidal osteomas (osseous choristomas) are presented. This rare, benign choroidal tumour is being recognized with increasing frequency, and is important to remember in the differential diagnosis of any unusual mass in the ocular fundus lest it be mistaken for a more sinister lesion. All three osteomas were demonstrated by ocular ultrasound (US), fluorescein angiography (FA) and computed tomography (CT) but none by plain radiography. None of the lesions was visible on magnetic resonance imaging (MRI); the reason for this is probably the bony nature of the tumours. The appearances of choroidal osteomas on US, FA, plain radiography and CT are discussed. To our knowledge this is the first report of a series of choroidal osteomas investigated by MR.

Magnetic resonance imaging. Diverse appearances of uveal malignant melanomas.

Fifteen patients with uveal malignant melanomas were studied by magnetic resonance imaging. The magnetic resonance imaging appearances varied from those that have been reported previously to be characteristic of these tumors. In our series, malignant melanomas were of high signal on the T1 sequence and of variable but usually also of high signal on the T2 and Short Tau Inversion Recovery (STIR) sequences, a signal combination rarely described before. We postulate that magnetic resonance imaging appearances may be dependent on variations in histologic factors and on the type and field strength of the scanner used. It is widely believed that the paramagnetic melanin in malignant melanomas gives these tumors characteristic magnetic resonance imaging appearances, but our finding of diverse magnetic resonance imaging appearances for proved malignant melanomas suggests that this may not always be the case. We advise caution in diagnosing malignant melanomas from magnetic resonance imaging appearances alone.

Laboratory investigation in the diagnosis of pulmonary thromboembolism.

Laboratory findings were compared with lung scans in a prospective study of 260 patients undergoing ventilation-perfusion (V/Q) lung scanning for suspected pulmonary thromboembolism. The best discrimination between different lung scan results was obtained from the level of plasma cross-linked fibrin degradation products, every patient with a scan indicating a high probability of thromboembolism having detectable levels. An acute phase response was demonstrated in patients with pulmonary thromboembolism by a raised neutrophil count and elevated levels of plasma fibrinogen and serum C-reactive protein. A normal level of serum C-reactive protein and/or plasma cross-linked fibrin degradation productions in blood taken within 4 days of onset of symptoms virtually excluded the diagnosis of pulmonary thromboembolism. Detection of free plasma DNA was not helpful in discriminating between groups with different lung scan results. Discriminant analysis was used to assess the variables examined and to derive diagnostic models. An accuracy of 78 per cent was obtained with one model for classifying test patients according to the three lung scan classes of low, intermediate and high probability. A second model, for distinguishing patients with a low and a high probability of pulmonary thromboembolism on the basis of lung scans, and a third for predicting those with a low probability on lung scan, were accurate in 94.6 per cent and 83.5 per cent of patients respectively. Discriminant models could be used in the diagnosis of pulmonary thromboembolism, especially when diagnostic imaging is not available.

Impedance plethysmography and thrombo-embolic disease.

This study compares the results of impedance plethysmography with lower limb venography in 68 patients referred for investigation of clinical deep vein thrombosis, and with the results of ventilation/perfusion isotope scans in 125 patients with suspected pulmonary embolism. Impedance plethysmography had a sensitivity of 100% and a specificity of 61% for the detection of thromboses involving popliteal or more proximal veins (30 patients), but a sensitivity of 90% and a specificity of 68% in the detection of thrombosis at any level, because of a low sensitivity in the detection of isolated calf vein thrombosis (60% in 10 patients). It is a non-invasive, portable and low-cost technique and, in centres where anticoagulation is only given to patients with popliteal or more proximal thrombosis, venography may only be necessary if impedance plethysmography is positive. It may also be of value in the assessment of patients with suspected pulmonary embolic disease and an indeterminate ventilation/perfusion lung scan.