[The value of magnetic resonance tomography (MRI) with reference to economic aspects of radiotherapy planning of vertebral metastases. A cost benefit analysis]. / Die Wertigkeit der Magnetresonanztomographie (MRT) unter ökonomischen Aspekten bei der Bestrahlungsplanung von Wirbelkörpermetastasen. Eine Kosten-Nutzen-Analyse.

Is magnetic resonance imaging (MRI) based target volume definition for treatment planning of vertebral metastasis effective under economic considerations. From 1994 to 1999, a total of 137 patients with bone metastases affecting the vertebral column underwent MRI of the cervical, thoracic, or lumbar spine for the treatment planning of palliative radiation therapy. The following radiation treatment consisted in a irradiation of the affected vertebral region up to a total dose of 30-40 Gy. The cost calculation for radiotherapy and magnetic resonance tomography was done using the common tariff model (EBM) of the German Health Insurances. In 73% of patients (101 patients), magnetic resonance imaging resulted in marked corrections of the irradiation fields which would have resulted in the necessity of treatment for recurrence in the case of treatment planning without MRI. Consequently, the higher cost of MRI of 345.00 DEM (176,40 EUR) lead to a saving of 497.00 DEM (254,11 EUR) compared to a recurrence treatment of 10 fractions and of 1,428.00 DEM (730,12 EUR) compared to 20 fractions. The transport expenses for the second treatment could be saved as well. Even under economic considerations MRI is effective.

[Sigmoidoperianal fistula associated with diverticulitis and Cul de Sac situation--diagnostics and therapy]. / Sigmoidoperianale Fistel durch Sigmadivertikulitis bei Cul de Sac-Syndrom--Diagnostik und Therapie.

We report on the case of a 64-year-old female patient who presented herself in our outpatient clinic because of a perianal fistula with recurrent abscesses. We describe the step diagnostics and the surgical treatment of the causal sigmoido-perianal fistula with diverticulitis and Cul de sac situation. Clinical examination, fistulography, colonoscopy and MRT were part of the precise representation and preparation for the high anterior rectosigmoidal resection with simultaneous rectopexy according to Sudeck which were performed without complications. The sigmoidoperianal fistula must be taken into account as a differential diagnosis of a recalcitrant high perianal fistula.

KAMEDIN: a telemedicine system for computer supported cooperative work and remote image analysis in radiology.

The software system KAMEDIN (Kooperatives Arbeiten und MEdizinische Diagnostik auf Innovativen Netzen) is a multimedia telemedicine system for exchange, cooperative diagnostics, and remote analysis of digital medical image data. It provides components for visualisation, processing, and synchronised audio-visual discussion of medical images. Techniques of computer supported cooperative work (CSCW) synchronise user interactions during a teleconference. Visibility of both local and remote cursor on the conference workstations facilitates telepointing and reinforces the conference partner's telepresence. Audio communication during teleconferences is supported by an integrated audio component. Furthermore, brain tissue segmentation with artificial neural networks can be performed on an external supercomputer as a remote image analysis procedure. KAMEDIN is designed as a low cost CSCW tool for ISDN based telecommunication. However it can be used on any TCP/IP supporting network. In a field test, KAMEDIN was installed in 15 clinics and medical departments to validate the systems' usability. The telemedicine system KAMEDIN has been developed, tested, and evaluated within a research project sponsored by German Telekom.

Image transfer and computer-supported cooperative diagnosis.

The KAMEDIN system was designed as a low-cost communication tool as part of a computer-supported cooperative work project that included synchronized user interaction, telepointing and audioconferencing. During a five-month field trial, it was used for medical image transfer and cooperative diagnosis in 14 clinics and medical departments in Germany. During the field test, 297 teleconsultations were performed via ISDN and 875 MByte of data were transferred. An image compression ratio of 2-3 was obtained, so that the total quantity of data transferred corresponded to 14,000-21,000 magnetic resonance images or 3500-5250 computerized tomography images. Furthermore, 694 local sessions were conducted for the preparation of teleconsultations and the review of transferred images. Participants learned to handle the KAMEDIN system in a few hours. This was mainly owing to the design of the user-oriented graphical user interface and the restriction of the system to a set of essential image-processing functions.

[Digital picture archiving, processing and communication in diagnostic imaging with a Siemens Network (SIENET): initial results]. / Digitale Bildarchivierung, -nachbearbeitung und -kommunikation in der bildgebenden Diagnostik mit einem Siemens-Netz (SIENET): Erste Erfahrungen.

The concept of Picture Archiving and Communication System (PACS) in digital imaging offers substantial advantages: better data security, faster access to archived images, simultaneous availability of images at different sites, minimal space demand for archive medium, retrospective image post-processing opportunities and lower costs resulting from reduced film consumption and length of stay. However, practical experiences concerning reliability and efficiency of real PAC networks in radiological departments have to be made yet in order to improve network structure, software design and hardware performance. The ongoing stepwise installation and test of a Siemens PACS (SIENET) at the Department of Radiology at the Medical University of Lübeck will support the introduction of PACS concept into radiological practice.

ISDN based teleradiology and image analysis with the software system KAMEDIN.

This contribution describes the software system KAMEDIN (Kooperatives Arbeiten und MEdizinische Diagnostik auf Innovativen Netzen) that is designed as an ISDN based computer supported cooperative work (CSCW) tool for usage in medical diagnostics. Medical image data from various sources (for example CT and MR) can be interchanged and analyzed in bilateral teleconferences via ISDN. During a cooperative session, user interactions for image processing etc., are synchronized and performed on both workstations, Features like telepointing, remote control, and audio connection enhance communication quality. With ISDN as a transmission line, widespread availability and low communication costs are achieved. Further, automatic tissue labeling in intracranial MR data can be invoked. For this purpose, artificial neural network classifiers such as multilayer perceptron and Kohenen feature map are integrated. Classification results can be viewed as 3D-reconstructions.

Neural network approach for computer-assisted interpretation of ultrasound images of the gallbladder.

Multi-formatted films of 90 ultrasound examinations of the gallbladder (stones 56 cases, sludge 20 cases, hydrops five cases, normal gallbladder nine cases) have been digitalized and stored in a personal computer. Image data of each examination was processed to extract a 19-dimensional vector that represents the essential diagnostic information of each examination. This vector was evaluated by three different classification algorithms: (1) classical nearest neighbor principle, (2) classical linear discriminant analysis, (3) multilayered backpropagation neural network. The correct classification rate was 64% (58/90) for the nearest neighbor principle, 97% (87/90) for the linear discriminant analysis, and 99% (89/90) for the backpropagation neural network. We conclude that, (1) automated classification of ultrasound images is possible for limited diagnostic problems, (2) a neural network approach can be used successfully for that goal, and (3) the efficiency of the more flexible neural network approach is comparable to large-scale classical methods.

Insufficient hemodialysis access fistulas: 18 months' experience in laser-supported dilation.

Patients with end-stage renal failure disease frequently develop venous stenoses or occlusions in their hemodialysis access fistulas caused by intimal fibrosis. A complete dilation with high pressure balloons up to 20 atm may be unsuccessful in those cases. We investigated two new pulsed dye laser devices for the ablation of obstructions, which were not adequately treatable with a previous balloon angioplasty. From November 1990 to April 1992 a total of 154 percutaneous transluminal angioplasties (PTAs) of hemodialysis access fistulas were performed. In 23 of them an additive laser angioplasty was necessary. Twenty patients with Cimino fistulas presented 28 stenoses and two occlusions, and three Goretex loops presented all occlusions. Two pulsed dye laser devices emitting at 504 nm and 595 nm wavelength were tested. Technical success was achieved in 22/23 cases, but clinical success was obtained in 20/23 patients because two early reocclusions caused by thrombosis appeared. Five restenoses occurred 2, 3, 10, and in two cases 14 months after angioplasty with a mean follow-up period of 13.5 (5-18) months. Pulsed dye laser ablation in hemodialysis access fistula lesions due to intimal fibrosis is a valuable enrichment of radiological recanalization techniques and an alternative to surgery if stand alone balloon PTA fails.

[The laser-assisted balloon angioplasty of insufficient hemodialysis-access fistulae]. / Lasergestützte Ballonangioplastie insuffizienter Hämodialysefisteln.

Patients with end-stage renal failure frequently develop venous stenoses or occlusions in their haemodialysis access fistulas caused by intimal fibrosis. A complete dilation with high pressure balloons up to 20 atm may be unsuccessful in such cases. We investigated two pulsed dye laser devices for the ablation of obstructions, which were not adequately treatable with a previous balloon angioplasty. From 11/90 to 4/92 a total amount of 154 PTAs of haemodialysis access fistulas were performed. In 23 of them additive laser angioplasty was necessary. 20 patients with Cimino fistulas presented 28 stenoses and two occlusions, whereas all the three patients with Goretex loops presented with occlusions. Two pulsed dye laser devices emitted at the wavelengths 504 nm (green) and 595 nm (red). Technical success was achieved in 22/23 cases, but clinical success was obtained in only 20/23 patients, due to two early reocclusions caused by thrombosis. 5 restenoses occurred two, three, 10, and twice 14 months after angioplasty with a mean follow-up period of 13.5 (5-18) months. Pulsed dye laser ablation in haemodialysis access fistula lesions due to intimal fibrosis greatly enriches radiological recanalisation techniques and is a valuable alternative to surgery if stand-alone balloon PTA fails.

[Thrombotic and thromboembolic occlusions of leg arteries and bypasses. Short-term versus long-term lysis]. / Thrombotische und thrombembolische Beinarterien- und Bypassverschlüsse. Kurzzeit- versus Langzeitlyse.

Since thrombolytic therapy is less invasive than operative thrombectomy, it is often used as initial treatment for thrombotic or thrombo-embolic occlusions of lower limb arteries or by-passes. We compared four patient groups with acute and subacute occlusions: 1. 19 patients with occluded by-passes treated by rapid lysis using 15.5 (2.5-35) mg rt-PA. 2. 12 patients with by-pass occlusions treated with initial rt-PA in a dose of 6.5 (2.5-12.5) mg followed by prolonged lysis with 5.6 (2.5-10) x 10(6) units of urokinase. 3. 16 patients with arterial occlusions treated by rapid lysis with 15 (2.5-25) mg rt-PA. 4. 14 patients with arterial occlusions given 10.5 (2.5-60) mg rt-PA followed by overnight treatment with 5.9 (2.5-15) x 10(6) units of urokinase. For by-pass recanalisation, prolonged lysis overnight had a success rate of 83% (10/12) which was better than short term lysis with a success rate of 74% (14/19). Similar results were obtained in arterial occlusions with a success rate of 86% (12/14) compared with 69% (11/16). Long term lysis did, however, have significantly more complications. In about one-third of cases further procedures had to be used in addition to lytic therapy.

Follow-up study of renal transplants by duplex Doppler and gray-scale ultrasound.

In the early postoperative period after renal transplantation 388 follow-up ultrasound examinations were performed in 77 patients. Over a period of 18 months standardized duplex indices (resistive index, pulsatility index) and gray-scale parameters (parenchyma/sinus index; medulla/cortex index) were sampled. These data were correlated retrospectively with clinical and pathological diagnoses. To delineate the individual course of duplex and gray-scale indices during different transplant diseases we created a new parameter: the MID (maximal index difference) which is a result of the difference between the highest index during the phase of renal dysfunction and the lowest index during the phase of normal renal function. This MID, calculated for duplex indices and for the parenchyma/sinus index, indicated significant differences in the behavior of renal transplants during the four main diseases: interstitial rejection, vascular rejection, acute tubular necrosis and Cyclosporine A nephrotoxicity. Using the MIDs, a table of cut-off values was established, which enables to differentiate retrospectively these four transplant complications with a sensitivity of 84% and specificity of 81%. In our opinion consequent follow-up examinations with duplex and gray-scale sonography should be performed, enabling sonography to become a helpful diagnostic instrument in the monitoring of renal transplants.

Non-absorbable fat-dense oral contrast agent for abdominal computed tomography.

Opacification of the gastrointestinal tract for CT scanning is usually achieved by oral administration of a diluted iodine solution or barium suspension. As high-density contrast agents often cause image degrading artifacts, we investigated the value of a paraffin-methylcellulose emulsion as an oral CT scanning agent. Diseases of the intestinum were clearly outlined with paraffin emulsion, and image degrading artifacts were virtually not encountered.

Initial clinical experience with a new pulsed dye laser device in angioplasty of limb ischemia and shunt fistula obstructions.

Selective plaque ablation with laser radiation at 405-530 nm in vitro has been reported. We investigated the possibilities of a new pulsed dye laser device for in vivo recanalization of arteries in ischemic lower limbs and stenoses/occlusions of arterio-venous hemodialysis shunt fistulae. A specially designed 9F or 7F multifiber catheter was used for treatment of 10 patients with lower limb artery obliterations and 11 patients with malfunctioning hemodialysis access fistulae (HAF). The recanalization technical success was 5/5 in the iliac arteries (IA), 4/5 in the superficial femoral arteries (SFA), and 11/11 in the HAF. Early re-occlusions occurred in one SFA and one IA, respectively, caused by very bad run-off. There was one clinically insignificant SFA perforation. Additional balloon angioplasty was considered necessary in 10/16 lesions. Mean ankle-arm index increased from 0.68 to 0.97. With two exceptions all HAF patients were re-integrated in the dialysis program. Pulsed dye laser angioplasty promises to be an effective and fast method for plaque ablation/debulking. The first clinical experience confirms previous in vitro results. In particular laser recanalization may become the method of choice for treatment of rigid HAF obstructions and it seems to be superior to vascular surgery or balloon angioplasty alone.

[Imaging diagnosis of parotid diseases--a comparison of methods]. / Bildgebende Diagnostik bei Parotiserkrankungen--ein Methodenvergleich.

Thirty-five patients with parotid gland disorders were ultrasonographically examined with a "small parts" scanner, as well as with high-resolution computed tomography, and conventional and digital subtracted sialography. The results were compared with clinical, surgical, and pathomorphological data. In cases of parotid gland masses, the sensitivity of sonography, CT, and sialography was 100%, 81%, and 70% respectively, while in cases of sialadenitis, sensitivity was 38%, 50%, and 75%. The image-quality of digital subtracted sialography was superior to conventional sialography in 94% of cases, the same in 6%, and inferior in none of the cases. It is concluded that in all cases of parotid gland diseases ultrasound should be the first imaging method. If a tumor is confirmed, no further pretherapeutic imaging will be necessary in most cases. If a tumor is not confirmed, digital subtracted sialography should be employed to visualize inflammatory changes.

[Selective catheter angiography using a translumbar technic]. / Selektive Katheterangiographie in translumbaler Technik.

By using a new 5-F-needle-sheath system for translumbar aortic puncture, it was possible to introduce 4-F-catheters of different lengths and shapes. In nine patients 19 vessels were selectively catheterised. There were no complications. The trans-lumbar approach to selective angiography is a simple and safe alternative to the more dangerous trans-brachial method.

Digital subtraction sialography, conventional sialography, high-resolution ultrasonography and computed tomography in the diagnosis of salivary gland diseases.

Forty-one patients with salivary gland disorders have been evaluated by digital subtraction sialography, conventional sialography, high-resolution ultrasonography and computed tomography, and the results compared with clinical, surgical and pathomorphological data. In the case of salivary gland masses, the sensitivity of ultrasonography, CT and digital subtraction sialography was 100%, 82% and 71%, respectively, while in the case of sialadenitis, the respective figures were 54%, 69% and 85%. The image quality of digital subtraction sialography was superior to that of conventional sialography in 80%, equal in 16%, and inferior in 3% of the examinations. We conclude that in all cases of salivary gland diseases ultrasound should be the first imaging procedure. If a tumour is not confirmed, digital subtraction sialography should be employed to visualise inflammatory changes, while in most cases of salivary gland masses no further imaging will be necessary.

Insufficient hemodialysis access fistulas: late results of treatment with percutaneous balloon angioplasty.

Forty-six patients with malfunctioning hemodialysis access fistulas were treated with balloon angioplasty. The initial percutaneous transluminal angioplasty procedure was successful in 16 (89%) of 18 patients with stenoses and in 13 (46%) of 28 with occlusions. In ten patients (seven with stenoses and three with occlusions) repeated dilation (two to five times; mean, two times) became necessary due to recurrent malfunction 1-24 months (mean, 6 months) after the first intervention. In the 16 patients with stenoses, the patency rate after 6 months was 93%; after 1 year, 91%; and after 2 years, 57%. In the 12 patients with occlusions, the rates were 80%, 50%, and 14%, respectively. Dilation of stenoses in malfunctioning hemodialysis fistulas is the procedure of choice. If hemodialysis shunts malfunction, immediate dilation of stenotic lesions should be performed to prevent occlusion.