Teleradiology requirements and aims in Germany and Europe: status at the beginning of 2000

Specific radiological requirements have to be considered for realization of telemedicine. In this article the goals and requirements for an extensive implementation of teleradiology are defined from the radiological user's point of view. Necessary medical, legal and professional prerequisites for teleradiology are presented. Superior requirements, such as data security and privacy or standardization of communication, must be realized. Application specific requirements, e. g. quality and extent of teleradiological functions as well as technological alternatives, are discussed. Each project must be carefully planned in relation to one's own needs, extent of functions and system selection. Topics like legal acceptance of electronic documentation, reimbursement of teleradiology and liability must be clarified in the future. Received: 20 January 2000; Revized: 19 April 2000; Accepted: 20 April 2000     

Cost-benefit study of different application scenarios in teleradiology

Summary With the increasing number of users and technical improvements, there are several application scenarios of teleradiology. To perform a cost-benefit analysis, an approach is presented, which focuses on both monetary and qualitative aspects. Process-related, qualitative and quantitative evaluations are described. The prestudy compares the radiological workflow before and after the introduction of a teleradiology system. A scoring model is part of the qualitative evaluation. The quantitative study focuses on costs and savings. Amortisation and a net present value of savings versus costs can be derived using dynamic investment methods. Savings can be achieved after a short time under ideal conditions, but there is no guarantee for a reimbursement for all systems. Eingegangen am 20. Dezember 1996 Angenommen am 6. Februar 1997     

Commercial teleradiology systems in Germany

Summary Teleradiologysystems can differ considerably in their features. The most important differences lie in the mode of image data acquisition, data transfer, data safety aspects and the possibilities of interaction between seperate teleradiology units. A selection of commercially available teleradiologysystems is presented and compared. Eingegangen am 3. Februar 1997 Angenommen am 19.Februar 1997     

Cardiac tumors

Summary Tumors of the heart are very rare. Due to the nonspecific clinical presentation the diagnosis is usually made by radiological procedures. Cardiac myxomas and thrombi are the most common cardiac masses. Two-dimensional echocardiography is the method of choice for the initial evaluation of cardiac tumors, because it permits the accurate determination of the tumor's size, localization, point of attachment, mobility and haemodynamic significance. Inadequate or nondiagnostic ultrasound examination and the need for preoperative assessment are indications for further examinations, such as magnetic resonance imaging (MRI) and computed tomography. Both these methods are helpful in the assessment of paracardiac structures and of the tumor invasion into great vessels and the mediastinum. MRI allows a limited degree of assessment of whether or not the tumor is malignant by soft tissue characterization. In the case of resectable, symptomatic, cardiac tumors surgical excision should be performed. Eingegangen am 23. Dezember 1996 Angenommen am 10. Januar 1997     

Imaging techniques in the diagnosis of coronary heart disease

Summary Coronary heart disease is the leading cause of death and disability worldwide. Coronary angiography makes it possible to visualize coronary artery stenosis and can be used for angioplasty and stent implantation; however, it does not allow the assessment of changes in myocardial microcirculation. The severity of an angiographically evaluated coronary stenosis does not always correspond to the extent of myocardial ischemia. Noninvasive techniques are needed to re-examine our reliance on coronary angiography and to explore the clinical value of the physiological assessment of coronary artery stenoses. Such noninvasive techniques might become important tools in the future following an overal evaluation of coronary morphology, myocardial function and perfusion ascertained by all available methods. Eingegangen am 8. Januar 1997 Angenommen am 9. Januar 1997     

Volvulus in childhood

Summary Gastric volvulus or volvulus of the small-bowel can occasionally be found in neonates and small infants. Since volvulus is an emergency case, the radiologist must know the characteristic radiological findings and the ultrasound signs in correlation to the clinical symptoms. Two forms of gastric volvulus can be distinguished: the organoaxial type and a mesenterioaxial form. Besides an idiopathic etiology, diaphragmatic alterations can be observed in children with volvulus of the stomach. Volvulus of the small-bowel occurs in children with malrotation type I or II or with nonrotation. Bile-stained vomiting starts within the first days of life and is followed by the clinical signs of high bowel obstruction and peritonitis. Primarily in cases of gastric volvulus, an ultrasound examination can show the wrong position of the stomach or the pyloric region. In cases of small-bowel volvulus, abnormal localization of the superior mesenteric artery can be demonstrated. The plain film features an upper small-bowel obstruction. Upper intestinal contrast studies may reveal the level of small-intestine obstruction. A contrast enema can rule out a concomitant colon nonrotation or malrotation. A rare form which can be misdiagnosed easily, is volvulus of the sigmoid with pathological elongation and positioning of the sigma. It appears mostly in school children with less urgent symptoms and can disappear spontaneously. A typical feature is pain in the left lower abdomen and complete obstruction in an opaque enema. Eingegangen am 30. Dezember 1996 Angenommen am 3. Januar 1997     

Gynecological disease causing acute abdominal pain in childhood

Summary In cases of acute abdominal pain in girls a gynecological cause must always be considered. Neoplasms and cystic adnexal lesions complicated by hemorrhage, torsion, and infarction can be diagnosed in childhood. Ovarian tumors without endocrine activity are frequently very large at the time of discovery. Intravaginal foreign bodies, inflammation, and congenital obstructive malformations are seldom found in patients with acute abdominal pain. Ultrasound has become the diagnostic method of choice. When used by an experienced examiner, its results are nearly as good as MRI. In evaluation with clinical data and serological results, an exact diagnosis can be made by ultrasound, even if the sonomorphological pattern seems confusing. Solid adnexal mass and complex malformations require MRI as a complementary diagnostic step. X-ray studies and computed tomography are less important diagnostic tools in girls with acute abdominal pain caused by gynecological disease. Eingegangen am 20. Dezember 1996 Angenommen am 5. Januar 1997     

Telemedicine – possibilities and perspectives

Summary The discussion about the implementation of telemedicine and teleresourcing and its consequences has been under way for some time now. The rate at which telemedical applications are being developed, leaves little time for consideration of the economic, scientific and social aspects. There is a need for integration of all the existing fragments into one coherent telemedical concept. Different aspects of telemedical concepts are discussed. Eingegangen am 20. Januar 1997 Angenommen am 19. Februar 1997     

Diagnostic imaging of aortic diseases

Summary The aim of this overview is the comparison between noninvasive tomographic imaging modalities such as surface echocardiography, transesophageal echocardiography, X-ray computed tomography and magnetic resonance imaging with the previous gold standard angiography in the setting of acute and chronic aortic diseases. Methods: The groundwork for the comparison between various noninvasive modalities is the validation of findings with angiography or intraoperative and histopathological results. Results and conclusions: Noninvasive modalities such as transesophageal echocardiography, X-ray computed tomography and magnetic resonance imaging are suitable methods for reliable diagnosis or exclusion of aortic dissection both in the ascending and descending segment of the thoracic aorta. Other more rare pathologies of the aorta such as intramural hemorrhage as a precursor of dissection, aortic ulcers, aneurysms as well as congenital and posttraumatic lesions may also be subjected to transesophageal echocardiography or magnetic resonance imaging with excellent sensitivity and specificity; both techniques have also proven to be safe procedures in critically ill patients and have, in our view, replaced angiography for the diagnosis of acute aortic syndromes. Thus, in acute aortic diseases invasive angiographic procedures should be relegated to a complementary role, while transesophageal echocardiography, X-ray computed tomography (especially helical CT) in acute, and magnetic resonance imaging in chronic cases represent prefered diagnostic options. In addition to primary diagnostics the noninvasive approaches using transesophageal echocardiography and magnetic resonance imaging are superbly suitable for serial follow-up imaging in all forms of aortic pathology. Eingegangen am 23. Januar 1997 Angenommen am 23. Januar 1997     

Legal aspects of teleradiology

Summary It is hoped that the implementation of teleradiology will improve the quality and economic effectiveness of health care in the future. The German federal government has submitted a bill for a legal statute, thereby creating the necessary framework to guarantee the essential “document security”. The responsibility of those involved with orderly data transmission as well as the limited responsibility for physicians' findings are both governed by general liability. General principles apply also with regard to professional discretion. Authorized utilization of external networks depends upon the quality of data security. Networks with unlimited public access may not be used without explicit consent from those concerned.      

Intussusception

Summary Intussusception is the most common abdominal emergency in infancy and childhood. Most cases are idiopathic ileocolic intussusceptions; rarely is a lead point present. Abdominal ultrasound is the imaging modality of choice for the demonstration as well as the exclusion of an intussusception. The target (transverse section) and pseudokidney (longitudinal section) signs are pathognomonic sonographic findings. Simultaneous depiction of lead points or lymph nodes or the presence of an entero-enteral intussusception may lead to different appearances. When an intussusception has been diagnosed with ultrasound, further complications such as small bowel obstruction or free intraperitoneal fluid have to be excluded at the same time. In addition, the perfusion of the intussusceptum can be evaluated with color Doppler ultrasound. There is general consensus that the only contraindications for conservative reduction are bowel perforation, peritonitis and hypovolemic shock. The oldest and most widespread method is hydrostatic reduction with barium under fluoroscopic control. Pneumatic reduction under fluoroscopic monitoring has gained more and more acceptance. An alternative technique is sonographically guided hydrostatic reduction with normal saline solution. Both latter methods are reported to have success rates of 80–90 % and are clearly superior to the barium technique. In our opinion ultrasound monitoring offers the most precise control of the whole reduction process, with distinct demonstration of the intraluminal structures, especially of the ileocecal valve and of a possible lead point. A complication can be recognized immediately. The primary advantage is the lack of radiation exposure. Therefore, with appropriate equipment and experience this method may be regarded as most promising in the management of intussusception in infancy and childhood. Eingegangen am 15. November 1996 Angenommen am 1. Dezember 1997     

Methods for quantitative assessment of tissue microcirculation using dynamic contrast-enhanced MR imaging

Summary The development of rapid magnetic resonance imaging (MRI) sequences makes it possible to detect the fast kinetics of tissue response after intraveneous administration of paramagnetic contrast media (CM), reflecting the status of tissue microcirculation. In this paper, the basic physical and tracer kinetic principles of dynamic relaxivity and susceptibility contrast MRI techniques are reviewed. The quantitative analysis of the acquired dynamic image data is broken up into an MR specific part, in which the observed signal variations are related to the CM concentration in the tissue, and an MR independent part, in which the computed concentration-time-courses are analyzed by tracer kinetic modeling. The purpose of the applied models is to describe the underlying physiological processes in mathematical terms and thus to enable the estimation of tissue specific parameters from measured dynamic image series. Whereas the capillary permeability can be estimated from dynamic relaxivity contrast enhanced MRI studies, the regional blood volume as well as the regional blood flow can be determined from dynamic susceptibility contrast enhanced image series. However, since there are no intravascular but only diffusible CM available at present, the application of the susceptibility technique is currently restricted to brain tissues with intact blood brain barrier. The practical realization of both dynamic MRI techniques is demonstrated by case studies. Eingegangen am 5. M?rz 1997 Angenommen am 24. April 1997     

Electron-beam-computed-tomography of the heart

Summary Using electron-beam computed tomography (EBCT) with short exposure times of 100 or 50 ms and the capability of acquiring up to 2 × 17 images/s it is possible to study most of the important morphological and functional determinants of the heart. Various examples of studies in acute and chronic cardiac diseases are shown to demonstrate the use of EBCT to determine quantitatively left ventricular volumes (ml), myocardial mass (g), wall thickness changes over the cardiac cycle (mm/s), myocardial perfusion (ml/100 g/min) and the extent of coronary calcification (calcium score) and qualitatively the state of the proximal 4–6 cm of the subepicardial coronary arteries. The knowledge of these determinants seems very useful in excluding cardiac dysfunction, in the early recognition of cardiac disease and in the evaluation of the haemodynamic severity of coronary artery stenotic lesions. Further interdisciplinary studies are necessary to assess the clinical validity of these cardiac determinants, especially myocardial perfusion, using this advanced CT technology. Eingegangen am 27. Januar 1997 Angenommen am 27. Januar 1997     

Intestinal emergencies in newborns

Summary Imaging plays a major role in most neonatal gastrointestinal emergencies. The role may vary from helping to establish a diagnosis, to the evaluation of associated abnormalities, to surgical planning, or to therapy for some conditions like meconium ileus or meconium plug syndrome. Plain radiographs and ultrasound serve a primary imaging modalities with bowel contrast examinations, CT scan, and MR imaging playing roles in more complex cases. Eingegangen am 30. Dezember 1996 Angenommen am 15. M?rz 1997     

Reactive thymic hyperplasia following treatment of ACTH-producing tumors

Summary Surgical or conservative treatment of ACTH-producing tumors results in acute drop of the previously excessively high cortisol levels. The following associated pathophysiological changes also occur in the organism's recovery from stress, such as trauma, operation or chemotherapy of tumors. Both cases result in a regeneration of the immune system, which might even be exalted. The corresponding radiographic feature is the ”rebound” enlargement of the thymus occuring about six months after remission of hypercortisolism. Histological examination reveals benign thymus hyperplasia. Especially in cases of still unkown primary tumor the appereance of this anterior mediastinal mass can lead to misdiagnosis. We present the cases of two patients with diffuse thymic hyperplasia following surgical and medical correction of hypercortisolism. One patient suffered from classic Cushing's disease responding to transsphenoidal resection of an ACTH-secreting pituitary microadenoma. Six months later CT of the chest incidentally demonstrated an anterior mediastinal mass known as thymic hyperplasia. The second patient presented with an ectopic, still unkown source of ACTH-production. Six months after medical correction of hypercortisolism CT of the thorax showed an enlargement of the anterior mediastinum. Thymectomy was performed in order to exclude thymus carcinoid. Histological examination revealed benign thymus hyperplasia with negative immunostaining. Conclusion: Radiologists and clinicians should be familiar with the pathophysiological changes resulting from precipitously dropping cortisol levels in order to prevent diagnostic errors and unnecessary operations. Eingegangen am 26. Mai 1997 Angenommen am 26. August 1997     

Study design in clinical radiology

Purpose: To review important aspects of study design in clinical radiology and to introduce the reader to the requirements of Good Clinical Practice (GCP). Methods: The European guidelines for GCP, the Declaration of Helsinki, the differentiation into study phases and the authors' own experience in open and sponsored clinical trials are the basis of this analysis. Results: Guideline such as GCP do not limit scientific freedom in research but define high standards for the well-being of patients and volunteers as well as guaranteeing scientific honesty. The benefits of defined data monitoring and the necessity of a prospective statistical concept are frequently underestimated. Conclusion: Correct study design has to be expected in radiology too. High standards guarantee accuracy and honesty of scientific studies. Only this can warrant the value for the patient of radiological diagnostics and therapy.      

Pericardium – Radiological diagnostics

Summary Evaluation of the pericardium using the capabilities of computed tomography (CT) and magnetic resonance imaging (MRI) remains one of the last requests to the radiologists within the spectrum of cardiac diagnostics. New technical developments in CT and MRI improve diagnostic acuracy in diagnosing pericardial disease and help to define adequate therapeutic management. The purpose of this article is to review the diagnostic possibilities of the radiologist in pericardial diseases with emphasis on CT and MRI. The anatomy of the normal pericardium including pericardial recessus and sinuses is reviewed followed by a brief discussion of congenital abnormalities. Particular attention is paid to acquired pericardial diseases including the potential characterization of pericardial effusions. Pericardial thickening and pericardial constrictions are discussed and the differentiation between pericardial constriction and restrictive cardiomyopathy is highlighted because of the therapeutic implications. Finally a brief review of primary and metastatic pericardial tumours is given. Eingegangen am 30. Januar 1997 Angenommen am 5. Februar 1997     

Pulmonary hypertension and cor pulmonale

Summary Pulmonary hypertension is a severe disorder of the pulmonary circulation and occurs in a variety of vascular and parenchymal lung diseases. It leads to volume and/or pressure overload of the right ventricle and finally to right heart failure. Pulmonary vascular diseases such as chronic pulmonary embolism cause a drastic increase in pulmonary vascular resistance, which results in extremely high pulmonary artery pressures that can even reach systemic levels. On the other hand, moderate pulmonary hypertension can also occur in chronic obstructive and restrictive lung diseases. For a long time, the diagnosis of pulmonary hypertension and cor pulmonale was based upon findings in echocardiography and right heart catheterization. Today modern imaging techniques allow the radiologist to assess right ventricular and pulmonary artery morphology and function. The application of spiral CT, electron-beam CT and MRT permits the diagnosis and differential diagnosis of pulmonary hypertension and also the evaluation and follow-up of underlying vascular or parenchymal lung disorders. In addition, quantification of right ventricular function and calculation of pulmonary hemodynamic parameters are possible. Eingegangen am 28. Januar 1997 Angenommen am 5. Februar 1997     

Appendicitis in childhood

Summary From 1989 to 1995 high-resolution ultrasonography (US) was performed in 3,546 children (age: 1–17 years) with clinically suspected appendicitis. A total of 518 patients underwent laparotomy; 420 had histologically proven acute or perforated appendicitis (prevalence 11.8 %). In these children, the sensitivity, specificity and overall accuracy of US examination were 90 %, 97 % and 96 % respectively. The use of US in clinically doubtful acute abdomen may allow earlier diagnosis of acute appendicitis; in 1995 the rate of unnecessary appendectomy was reduced to 13 %. Eingegangen am 15. Dezember 1996 Angenommen am 5. Januar 1997     

Qualitative und quantitative assessment of myocardial perfusion using magnetic resonance imaging

Summary Purpose: Purpose of this study was to test a triple slice saturation recovery turbo FLASH sequence for myocardial perfusion imaging. In addition data-evaluation-tools for qualitative and quantitative perfusion parameters are presented and preliminary tested. Material and Methods: We examined 8 healthy volunteers and 4 patients with myocardial infarction. Parameters of the saturation recovery turbo FLASH sequence were as follows: TR = 2.5 msec, TE = 1.2 msec, α = 8 °, 3 slices, thickness 10 mm. For data analysis signal-intensity time curves were calculated pixel by pixel and evaluated for signal-intensity-increase over baseline and signal-intensity-upslope. Images were displayed color-coded. For quantitative data analysis we used the indicator dilution theory and developed a deconvolution algorithm which takes the arterial input function into account to calculate the myocardial mean transit time (MTT). Results: The color-coded parametermaps showed uniform conditions in normal myocardium of volunteers, but reduced signal-intensity-increase over baseline and signal-intensity-upslope for infarcted areas in patients. The MTTs calculated using our algorithm were significantly shorter than those assessed with previous methods and matched better with values derived from literature. Infarcted areas show prolonged MTTs in comparison to normal myocardium. Conclusion: A triple slice saturation recovery turbo FLASH sequence is suitable for myocardial perfusion imaging. Color-coded parametermaps can visualize hypoperfused areas. For calculating myocardial MTTs using indicator dilution therapy a deconvolution algorithm is necessary. Eingegangen am 23. M?rz 1997 Angenommen am 26. M?rz 1997