[Comparison of time-oriented cost accounting catalogs to control a department of radiology]. / Vergleich zeitorientierter Leistungskataloge zum Controlling einer radiologischen Abteilung.

PURPOSE: Within a hospital, the radiology department has taken over the role of a cost center. Cost accounting can be applied to analyze the costs for the performance of services. By assigning the expenditures of resources to the service, the cash value can directly be distributed to the costs of equipment, material and rooms. Time-oriented catalogs of services are predefined to calculate the number of the employees for a radiology department. Using our own survey of time data, we examined whether such catalogs correctly represent the time consumed in a radiology department. Only services relevant for the turnover were compared. MATERIALS AND METHODS: For 96 primary radiological services defined by the score-oriented German fee catalog for physicians (Gebuhrenordnung fur Arzte), a ranking list was made for the annual procedures in descending frequency order. According to the Pareto principle, the 11 services with the highest frequency were chosen and the time consumed for the technical and medical services was collected over a period of 2 months. This survey was compared with the time-oriented catalogs TARMED and EBM 2000plus. RESULTS: The included 11 relevant radiological services represented 80.3 % of the annual procedures of our radiology department. When comparing the technical services between the time-oriented catalogs and our own survey, TARMED gives a better description of the time consumed in 7 of the 11 services and EMB 2000plus in 3 services. When comparing the medical services, TARMED gives a better description of the time consumed in 6 of the 11 services and EBM 2000plus in 4 services. When averaging all the radiological services, TARMED overestimates the current number of physicians necessary for primary reading by a factor of 10.0 % and EBM 2000plus by a factor of 2.6 %. CONCLUSION: As to the time spent on performing the relevant radiological services, TARMED is slightly superior to describe the radiology department of a hospital than EBM 2000plus. For calculating the number of physicians necessary for primary reading, EBM 2000plus is superior to TARMED.

[Computer simulation of a clinical magnet resonance tomography scanner for training purposes]. / Computersimulation eines klinischen Magnetresonanztomographen für Ausbildungszwecke.

PURPOSE: The idea for this project was born by the necessity to offer medical students an easy approach to the theoretical basics of magnetic resonance imaging. The aim was to simulate the features and functions of such a scanner on a commercially available computer by means of a computer program. MATERIALS AND METHODS: The simulation was programmed in pure Java under the GNU General Public License and is freely available for a commercially available computer with Windows, Macintosh or Linux operating system. The graphic user interface is oriented to a real scanner. In an external program parameter, images for the proton density and the relaxation times T1 and T2 are calculated on the basis of clinical examinations. From this, the image calculation is carried out in the simulation program pixel by pixel on the basis of a pulse sequence chosen and modified by the user. The images can be stored and printed. In addition, it is possible to display and modify k-space images. RESULTS: Seven classes of pulse sequences are implemented and up to 14 relevant sequence parameters, such as repetition time and echo time, can be altered. Aliasing and motion artifacts can be simulated. As the image calculation only takes a few seconds, interactive working is possible. CONCLUSION: The simulation has been used in the university education for more than 1 year, successfully illustrating the dependence of the MR images on the measuring parameters. This should facititate the approach of students to the understanding MR imaging in the future.

[Development of a secure and cost-effective infrastructure for the access of arbitrary web-based image distribution systems]. / Entwicklung einer sicheren und kostengünstigen Infrastruktur zum Zugriff auf beliebige webbasierte Bildverteilungssysteme.

PURPOSE: To build an infrastructure that enables radiologists on-call and external users a teleradiological access to the HTML-based image distribution system inside the hospital via internet. In addition, no investment costs should arise on the user side and the image data should be sent renamed using cryptographic techniques. MATERIALS AND METHODS: A pure HTML-based system manages the image distribution inside the hospital, with an open source project extending this system through a secure gateway outside the firewall of the hospital. The gateway handles the communication between the external users and the HTML server within the network of the hospital. A second firewall is installed between the gateway and the external users and builds up a virtual private network (VPN). A connection between the gateway and the external user is only acknowledged if the computers involved authenticate each other via certificates and the external users authenticate via a multi-stage password system. All data are transferred encrypted. External users get only access to images that have been renamed to a pseudonym by means of automated processing before. RESULTS: With an ADSL internet access, external users achieve an image load frequency of 0.4 CT images per second. More than 90 % of the delay during image transfer results from security checks within the firewalls. Data passing the gateway induce no measurable delay. CONCLUSION: Project goals were realized by means of an infrastructure that works vendor independently with any HTML-based image distribution systems. The requirements of data security were realized using state-of-the-art web techniques. Adequate access and transfer speed lead to a widespread acceptance of the system on the part of external users.

Contrast-enhanced magnetic resonance angiography of mammary artery grafts after minimally invasive coronary bypass surgery.

BACKGROUND: The aim of the study was to investigate the application of the contrast-enhanced magnetic resonance angiography (CE-MRA) for the visualization of left internal mammary artery (LIMA) bypass. METHODS: A total of 30 patients with LIMA bypass (22 men, 8 women, 35 to 77 years) received a CE-MRA 4 to 20 days after surgery. The non-ECG-triggered CE-MRA was performed during expiration using a body array coil at a 1.5 Tesla scanner (Magnetom-Vision). A three-dimensional gradient-echo sequence with slice interpolation technique was applied. For the three-dimensional visualization, single coronal slices were postprocessed with maximal intensity projection. Of 30 patients 22 agreed to a comparative coronary angiography. RESULTS: Five bypasses were identified up to the end-to-side anastomosis. A total of 80% of the bypass course was detectable in 13 patients and 60% in 11 patients. In two LIMA bypasses only 30% of the proximal part could be viewed; one was found by conventional coronary angiography to be occluded. The other conventional coronary angiography showed the LIMA bypass to be patent. CONCLUSIONS: The complete course of the LIMA bypass to the left anterior descending coronary artery can be visualized by the MRA technique. The most reliable imaging of the distal anastomosis can be realized by reducing the negative influence of the beating heart.

Renal artery stenosis: changes in intrarenal Doppler waveform following percutaneous transluminal angioplasty.

PURPOSE: To examine the extent of the changes in the intrarenal spectral waveform patterns after percutaneous transluminal angioplasty (PTA) and whether there is a correlation with the angiographic and clinical results. METHODS: In 44 patients with 68 PTAs we analyzed the intrarenal spectral waveform regarding the existence of a tardus-parvus pattern before and after PTA. RESULTS: In 51 of the 60 cases with a tardus-parvus pattern prior to PTA, a complete normalization of the spectral wave-form was noted. There was no correlation between the Doppler result after PTA and the angiographic and clinical result. In contrast there was a significant correlation between the Doppler result before PTA and the clinical outcome: patients with a normal intrarenal spectral waveform before PTA showed no improvement in their arterial hypertension. CONCLUSION: Our results indicate that a patient with a normal spectral waveform analysis does not response to PTA. However, there is still an unpredictable clinical response even if a patient has an abnormal intrarenal spectral waveform prior to PTA and a complete normalization after PTA.

[Duplex sonography of renal artery stenosis: potentials and limits of frequency spectrum analysis of arterial segments compared with angiography]. / Duplexsonographie der Nierenarterienstenose: Möglichkeiten und Grenzen der Frequenzspektrumanalyse der Segmentarterien im Vergleich zur Angiographie.

PURPOSE: The aim of this prospective study was to evaluate the potentials and limits of Doppler waveform analysis of intrarenal vessels in patients with suspected renal artery stenosis. MATERIAL AND METHODS: In a three-year study we compared our colour Doppler results of 111 patients with the angiography results. Evaluated parameters were acceleration time (AT), acceleration index (AI) and early systolic peak (ESP). RESULTS: The sensitivity of severe stenoses (> or = 70%) was 89%. In moderate stenoses (50-70%) it was possible to increase the sensitivity from 56% to 76% if a comparison with the contralateral side was included. The specificity was 91%. Causes for limited sensitivity and specificity were poor examination conditions, stenoses of accessory renal arteries and moderate stenoses as well as diffuse non-stenosing lesions. CONCLUSION: In comparison with angiography, the diagnostic value of Doppler waveform analysis in the detection of renal artery stenoses has specific limitations. In significant stenoses, however, additional valuable haemodynamic information, useful for PTA, can be obtained by this easy and accessible method.

[Pontine and extra-pontine myelinolysis. Early diagnostic and prognostic value of cerebral CT and MRI]. / Pontine und extrapontine Myelinolysen. Frühdiagnostischer und prognostischer Wert von zerebralem CT und MRT.

Retrospective examination of 44 patients with central pontine and/or extrapontine myelinolysis leads to the conclusion that in early diagnostics cerebral NMR is superior to cCT. T2-weighted images turned out to be the most sensitive parameter. Frequent contrast-medium enhancement early in the course up to 4 weeks after clinical manifestation in 7 patients underlines the pathogenetic idea of an initial transient blood-brain barrier. According to our results, central-pontine myelinolysis (CPM) proof by NMR can be expected after 1 week. During the clinical course, cCT and NMR findings showed no regression. Also no connection was noted between the size of the pontine lesion and the favorable clinical course in 72.2% of the patients, nor was there a correlation with the extent of the neurological symptoms at the crisis of the disease. Altogether, cCT and NMR are irrelevant for the prognosis of cerebral myelinolysis.

[Lacrimal duct recanalization with balloon catheter]. / Tränenwegrekanalisation mit Ballonkatheter.

In dilation of nasolacrimal duct stenosis materials now being used originally were developed for percutaneous transluminal coronary angioplasty (PTCA). Suitable modifications of the angioplasty equipment could improve therapeutic results and thus influence the area of indication of this new technique. In addition to the standard PTCA equipment, we used a cannula designed to fit the guide wire, leading to less traumatic intubation of the lacrimal duct and allowing radiographic control of the recanalization procedure. Five patients showing relative stenosis and ten patients showing complete obstruction of the nasolacrimal duct were treated by dacryocystoplasty. Clinical and radiographic follow-up was done over a period of 6 months. In a total of seven patients, dilation proved successful. Out of these, four showed stenosis (80% recanalization rate) and three complete obstruction (30% recanalization rate) before dilation. Recanalization by dilation using balloon catheters seems to be possible even in cases of complete nasolacrimal duct obstruction. However, the success rate is considerably lower than in relative stenosis.

Bilateral suppression of the sympathetic nervous system in hemispheric brain infarction.

To assess sympathetic system function after hemispheric brain infarction rostral to the hypothalamus we investigated 24 patients with infarction in the territory of the middle cerebral artery. Anisocoria and basal lacrimal gland secretion were determined. The ninhydrin test was performed and the sympathetic skin response recorded in both hands and feet. The functions assessed by these tests were found to be reduced bilaterally. No significant lateralisation of the sympathetic nervous system could be demonstrated.

[A rare form of heart metastasis: hypernephroma. Successful surgical treatment]. / Seltene Form von Herzmetastasen: Hypernephrome. Erfolgreiche chirurgische Behandlung.

An unusual cardiac metastasis, occurring in a 63-year-old man 19 years after nephrectomy because of renal cell carcinoma, is reported. The tumor extended from the right ventricle apex to the mid-portion of the interventricular septum. A complete excision could be achieved. To our knowledge, this is the third case of a renal cell carcinoma metastasis to the right ventricle which could be detected during a patient's lifetime and treated surgically. A review of the literature is also reported.

[Magnitude contrast angiography in peripheral arterial occlusive disease of the lower extremities]. / Magnitude-Contrast-Angiographie bei peripherer arterieller Verschlusskrankheit der unteren Extremitäten.

PURPOSE: To assess the clinical value of magnitude contrast angiography in arteriosclerosis of the lower limb. MATERIAL AND METHODS: 187 examinations were done in 105 patients with arteriosclerotic lesions of the femoropopliteal vessels. The MRA results were compared to DSA and conventional angiography. 36 patients were investigated before and after angioplasty. RESULTS: Occlusions were detected correctly in all cases. In mild and moderate stenoses there was 90% agreement. High-grade stenoses may simulate occlusions. All interruptions of the signal with a length of 1 to 10 mm have to be read as high-grade stenoses (MRA sensitivity was 0.96 and specificity 0.94). In patients with low cardiac output MRA may be advantageous in comparison to DSA: collaterals and vessels distal to occlusions were visualized better in MRA. Axial scans show morphology of stenoses and occlusions and influenced the choice of treatment in 6 cases. In 3 cases, thrombotic material and calcified plaque were distinguished. After angioplasty vessel wall lesions such as dissection of the intima or compressed plaque inside the vessel wall were well visualized. Agreement was 92% with MRA as opposed to lesser values with DSA.

[US Doppler guide wire. Initial experiences in angioplasty of peripheral blood vessels]. / US-Doppler-Führungsdraht. Erste Erfahrungen bei der Angioplastie peripherer Gefässe.

Forty-two patients underwent endoluminal Doppler examination of blood flow velocity proximally, at the stenosis and distal to it by means of a 0.018 in. Doppler guide wire. The method was found to be an accurate tool for documentation of a wide spectrum of stenoses of different morphology. The changes induced by percutaneous transluminal angioplasty (PTA)-hemodynamic changes as well as vascular wall lesions-could be documented precisely. Remaining stenoses after PTA were precisely verified as compared to angiography. In multiple stenoses or in stenoses with pure run-off, the hemodynamic significance of the lesion was evaluated. Intravascular Doppler flow measurement is valuable in angiographically imprecise cases. The method fits well into the angiographic routine examination.

Tumor in the horseshoe kidney: clinical implications and review of embryogenesis.

We report on 3 patients with tumor in a horseshoe kidney, 1 of whom had bilateral tumor (renal cell cancer on the right side and urothelial cancer on the left side). Tumors that arise predominantly in the bridge of a horseshoe kidney can mimic the symptoms of an intra-abdominal disease process. Besides routine diagnostic procedures, angiography is essential to plan the surgical approach, which in principle should be organ-sparing. The literature of the embryology of the horseshoe kidney was reviewed for a relationship between the abnormal renal development and the site of tumorigenesis, and for development of a key for the wide variation of blood supply. Recently reported data suggest that the theory of a mechanical fusion is valid only for horseshoe kidneys with a fibrous isthmus but that an abnormal migration of the posterior nephrogenic area causes the majority of horseshoe kidneys in which the isthmus consists of parenchyma. Development of the isthmus through abnormal migration could predispose this location for renal cell cancer and would explain the varying forms of blood supply. Additionally, this hypothesis supports the previously raised assumption that horseshoe kidneys may be the result of teratogenic factors, which also may be responsible for the known increased incidence of related congenital anomalies and of nephroblastoma.

The nutcracker syndrome: new aspects of pathophysiology, diagnosis and treatment.

Magnetic resonance imaging (MRI) was used to study vascular anatomy in 3 patients with the nutcracker syndrome and in 10 healthy volunteers. From these studies an abnormal branching of the superior mesenteric artery from the aorta was identified as being the cause of the nutcracker syndrome. Consequently, surgical transposition of the left renal vein to achieve an unobstructed renal venous backflow was performed successfully in 2 patients, while 1 underwent nephrectomy. In 1 patient adjuvant ureteral instrumentation became necessary to aid occlusion of persisting shunts between peripelvic venous varicosities and the urinary tract. Awareness of the pathophysiology of the nutcracker syndrome ensures an early diagnosis, which should be confirmed by a combination of diagnostic procedures, including MRI.

MR imaging in the differential diagnosis of scrotal and testicular disease.

It is frequently impossible to discriminate between various causes of scrotal pain and swelling by means of clinical examination and ultrasound (US) alone. Surgical exploration is necessary in cases of indefinite differential diagnosis. For evaluation of the diagnostic potential of magnetic resonance (MR) imaging in scrotal disease, 200 patients with testicular abnormalities were studied. For 74 of these patients, the diagnosis was cancer, based on clinical and US findings. MR imaging demonstrated malignant disease in 54 patients and benign disease in 20. All of the MR imaging findings were confirmed at surgical biopsy. Despite high costs of the procedure, the authors believe that MR imaging is a useful aid for diagnosis in cases of indefinite findings in scrotal and testicular disease.

[The clinical value of MRT in diseases of the testis and scrotum]. / Klinische Wertigkeit der MRT bei Erkrankungen der Hoden und des Skrotums.

Since 1986 more than 150 patients with testicular carcinoma, trauma or chronic inflammation and subacute torsion were investigated with MRT. Using a 1.5 Tesla-Magnetom (Siemens) with surface coils and a special Helmholtz coil, we imaged T1-weighted, proton-density and T2-weighted coronary and axial slices. The excellent spatial resolution facilitated the imaging of fine structures as the septula testis. In 55 surgically proven cases the proof or rejection of a testicular tumour was always possible without false negative or positive cases. We were also able to correlate certain types of tumours with the imaged morphologic structure. Embryonal carcinomas showed typical focal hemorrhages. Pure seminomas showed a clean cut surface, correlating with that of the surgical preparation. The T2 image gave always a low intensity signal. Beta-HCG-positive seminomas showed different signal patterns. Inflammatory processes in epididymitis were detected, as well torsion of the testicles. In traumatic conditions a differentiation of a ruptured tunica albuginea as an indication for surgery was possible. MRT is an important contribution for the indication of urological surgery. Unnecessary surgery of the testes can be prevented, small tumours can be detected at an early stage and can be differentiated from other conditions.

[Radiological findings in Recklinghausen's neurofibromatosis]. / Radiologische Befunde bei der Neurofibromatose von Recklinghausen.

The basic abnormality of neurofibromatosis consists not only of a maldevelopment of the neuroectoderm but also of the mesoderm. Therefore any organ or system of the body may be involved. Following a short clinical review of the central (acoustic) and peripheral type the well known and the more unusual radiographic findings are summarized. They include cranial and intracranial manifestations (orbitosphenoid dysplasia, bone defects of the skull, acoustic neuroma, glioma of the optic nerve and chiasm, meningioma), spinal lesions (scoliosis, vertebral scalloping, meningocele, neuroma, ependymoma), skeletal abnormalities (pseudarthrosis), cardiovascular manifestations, pulmonary fibrosis, tumors of the gastrointestinal and urinary tract and different endocrinopathies. Some of the roentgenologic symptoms are very characteristic and allow definitive diagnosis.

[Clinical experiences with arterial embolization of kidney tumors with ethanol]. / Klinische Erfahrungen mit der arteriellen Embolisation von Nierentumoren mit Athanol.

Based on 584 compiled cases of renal tumour embolization the materials used, the results and complications, are analyzed. The most serious complication proved to be the displacement and dislocation of particles from the embolization. Personal experience with 102 of our patients confirmed these results. In our clinics we have carried out tumour embolization in 20 patients using 95% alcohol since 1980. The first results are presented. The particular advantages of embolization using ethanol are: 1. The high risk of dispersal of particles from an embolization is eliminated. 2. It leads not only to destruction of the vascular system but also of the peripheral tissues as well to an extent rarely seen with the majority of other embolization materials. Attention must also be drawn to the comparatively safe and simple usage of ethanol during embolization.