Technical note: gold marker implants and high-frequency jet ventilation for stereotactic, single-dose irradiation of liver tumors.

With reference to radiosurgery of the liver, we describe techniques designed to solve the methodological problem of striking targets subject to respiratory motion with the necessary precision. Implanting a gold marker in the vicinity of the liver tumor was the first step in ensuring the reproducibility of the isocenter's position. An 18-karat gold rod measuring 1.9 x 3 mm was implanted approximately 2 cm from the edge of the tumor as this was displayed in the spiral, thin-slice CT with contrast media. Both the implantation of the marker and the required, CT-controlled biopsy of the liver tumor can be achieved simultaneously with the same puncture needle. The efficiency of high-frequency jet ventilation (HFJV) in neutralizing the targeted organ's respiratory motion during stereotactic single-dose irradiation was evaluated. The procedure was carried out on ten patients without any complications. In the time between treatment planning and irradiation (3 days), no significant marker migration was observable. In all cases, the gold marker (volume: 7.5 mm(3)) was readily observable in the treatment beam using portal imaging. HFJV provided reliable immobilization. The liver motion in each anesthetized patient was limited to under 3.0 mm in all directions. Thus, the correct field settings and target reproducibility were able to be analyzed and documented during the irradiation. The combination of marker and HFJV enables the determination of stereotactic coordinates directly related to the liver itself and, in this way, stereotactic radiation treatment of liver tumors is freed from the uncertainties involved in orientation to bony landmarks, in respiratory motion, and in changes of position in the stereotactic body frame. The method is feasible and can improve the accuracy of stereotactic body radiation therapy.

Angiographic detection of gastrointestinal bleeding. An experimental comparison of conventional screen-film angiography and digital subtraction angiography.

RATIONALE AND OBJECTIVES: The authors experimentally assess and compare the detection limit of gastrointestinal bleeding in digital subtraction angiography (DSA) and conventional screen-film angiography. MATERIALS AND METHODS: Arterial blood flow was simulated using a tube model in which bleeding was imitated by exudation of liquid containing contrast material. Gut peristalsis was imitated using silicone tubes filled with air and liquid. Images were acquired by DSA and conventional screen-film angiography. The iodine concentration was increased in increments from 1 mg I/mL, with and without simulated peristalsis, and with both free and circumscribed extravasation of contrast material. RESULTS: The detection limit for free extravasation in DSA was 1 mg I/mL without peristalsis and 60 mg I/mL with peristalsis. The corresponding figures for circumscribed extravasation were 1 mg I/mL and 34 mg I/mL. The detection limit for free extravasation in screen-film angiography was 172 mg I/mL both with and without simulated peristalsis. Circumscribed extravasation was detected at 9 mg I/mL without peristalsis and 7 mg I/mL with peristalsis. CONCLUSION: Digital subtraction angiography is the more sensitive angiographic technique for detection of gastrointestinal bleeding and is superior to conventional screen-film angiography, provided that it is performed with adequate parasym-pathicolysis and suspended respiration. Only when these requirements cannot be achieved is screen-film angiography advantageous.

Calculation of flow velocities from the geometrical shape of contrast agent-induced time-density curves using DSA.

A method for the calculation of flow velocities in vessels is introduced. The method is validated by measurements with an artificial model. Measurements with the carrier fluids sodium chloride solution and human blood using various scattering objects, show good correlation (r greater than +0.9) of the calculated and volumetrically measured velocities. With a menu-oriented computer program, measurement of flow velocities on DSA series can be made following the routine clinical examination.

[High-resolution MR tomography of the hand: normal anatomy]. / Hochauflösende MR-Tomographie der Hand: Normalanatomie.

By using surface coils and a high resolution matrix, the images from MR tomography of small objects can be greatly improved. Normal subjects have been examined in order to demonstrate the usefulness of MR tomography for the examination of bones and soft tissues in the normal hand.

[In vitro measurement of intravascular blood flow with color Doppler sonography]. / In-vitro-messung des intravasalen Blutflusses mit der Farb-Doppler-Sonographie.

The accuracy of colour Doppler sonography for measuring various aspects of intravascular flow (volume and velocity), under varying conditions, was studied experimentally. The effect of variable Doppler angles, different flow paths, frequency and vessel diameter on flow profiles was examined. At all levels of measurement (range 14 ml/min to 566 ml/min) there was a very close correlation between the actual and measured values (r greater than 0.99) and high accuracy. In the detection of very slow flow rates, the use of a specific high pass filter technique was able to quantify blood flow velocities of just under 1 cm./second. Multigated colour Doppler sonography is better for measuring flow volumes than a single channel duplex system.

[Measurement of absolute intravascular flow velocity using digital subtraction angiography]. / Messung der absoluten intravasalen Strömungsgeschwindigkeit mit der digitalen Subtraktionsangiographie.

Experiments on phantoms showed very good correlation between flow velocity, as calculated from time-density curves, and theoretical values. After further development using an inter-active computer programme, DSA measurements of flow velocity are now undergoing further experimental investigation, but are also available for routine clinical examination.

[Digital image intensifier radiography and film-screen combinations in pulmonary nodules]. / Digitale BV-Radiographie und Film-Folien-Kombination bei Lungenrundherden.

30 patients with known or suspected pulmonary nodules were examined using a digital image intensifier radiography system, a conventional radiography system and a tomography of the whole lung. 73.8% of the pulmonary nodules detected with tomography were also detected with the digital system, 69.1% with the conventional system. There was no significant difference between the two systems comparing false positive and false negative diagnoses. Regarding the dose reduction to nearly 25% of that of a conventional examination the digital technique should be preferred to the conventional technique, if pulmonary nodules are suspected.

[Imaging properties of digital image-intensifier radiography compared to the conventional x-ray technic for chest pictures]. / Abbildungseigenschaften der Digitalen BV-Radiographie im Vergleich zur konventionellen Röntgentechnik für Thoraxaufnahmen.

Projection properties of a digital fluorographic system for chest examinations are examined using varying test phantoms. A maximal geometric distortion of +14% between the centre and the periphery of the image intensifier and a maximal spatial resolution of 2.6 LP/mm is found. Contrast detail diagrams are used to show the combination of spatial and contrast resolution of the system. Compared with diagrams for conventional radiographic systems there is a significant loss of resolution.

[Magnetic resonance tomography of children with surgically treated anal and rectal atresia]. / Kernspintomographie (KST) bei Kindern mit operierten Anal- und Rektumatresien.

MRI of the pelvis was performed in 17 children following surgical correction of anal and rectal atresias and in five children without ano-rectal malformations. A muscle score was used to characterize the muscles of the pelvic floor and their relationship to the rectum. There was close agreement between the MRI muscle score and clinical continence. MRI provided additional information that should improve continence following conservative and surgical treatment.

[Can digital selenium-based radiography in thoracic diagnosis replace the analog x-ray imaging technic?]. / Kann die digitale Selenradiographie in der Thoraxdiagnostik die analoge Röntgenaufnahmetechnik ersetzen?

PURPOSE: To find out the diagnostic value of digital selenium radiography, we compared the image quality of chest x-ray images from 50 patients who had been examined via conventional chest x-ray and digital selenium radiography of the chest. METHOD: 50 patients with a malignant melanoma underwent chest x-ray within 3 months in conventional technique and with digital selenium radiography (Thoravision: Philips Medical Systems, Hamburg, Germany). In this period none of the patients showed a difference in respect of clinical status or radiological diagnosis. Simultaneous examinations on the same day were not performed to avoid unnecessary exposure to x-rays. The digital and conventional images were compared by 4 radiologists with regard to image quality by the detection of defined anatomic structures. RESULTS: Image quality of digital selenium radiography was considered superior to that of conventional chest x-rays in the mediastinum, the retrocardiac and retrodiaphragmatic areas, the superior and inferior lobes of the lung especially near the parietal pleura, and the chest wall. CONCLUSIONS: Compared to analogous techniques there is no loss of image information when employing digital selenium radiography in chest x-rays. On the contrary, new assessment criteria may be gained. We conclude that digital selenium radiography offers diagnostic advantages in chest x-ray examination.

[X-ray studies of the peripheral joints: a comparison of digital luminescence radiography (DLR) and film-screen systems]. / Röntgenuntersuchungen der peripheren Gelenke: Vergleich der digitalen Lumineszenzradiographie (DLR) mit Filmfoliensystem.

175 matched skeletal x-ray examinations were carried out by digital luminescent radiography (DLR) and conventional screen-film system combinations. In digital luminescent radiography (DLR) two differently postprocessed images were obtained from one x-ray exposure: A display with low spatial frequency enhancement was opposed to a second display with high edge enhancement. Conventional and digital images were evaluated randomly and separately by four radiologists using a questionnaire. DLR proved to be diagnostically equivalent to the conventional technique except for a diminished visibility of subtle erosions and fissures. As major advantages of DLR maybe pointed out that faulty exposures were avoided by the automatic adjustment of image brightness and that the soft tissue margins could be more easily delineated in displays with high edge enhancement than in conventional radiography. However, digital displays with high edge enhancement did not provide additional diagnostic information and led to artifacts at the edges of metal prostheses.

[Digital selenium radiography: a comparison of the picture quality of thoracic images in normal and reduced image formats based on the structural anatomical details]. / Digitale Selenradiographie: Vergleich der Bildqualität von Thoraxaufnahmen in normalem und verkleinertem Bildformat anhand anatomischer Detailstrukturen.

PURPOSE: Is there a loss of information when using selenium radiographic images displayed with reduced image format compared to full format? METHOD: Digital selenium radiographic chest images in two planes were obtained in 35 patients for medical reasons. The digital data sets of each patient were separately displayed in full format on two different films and were printed in reduced format on one film. The format was reduced to 61% of the full format using an acquisition matrix of 2166 x 2488 pixels, an image display matrix of 4000 x 5000 pixels and a film format of 43 x 49 cm. All images were anonymously evaluated by four independent readers using a questionnaire concerning anatomic structures. RESULTS: Format reduction did not result in a loss of information in diagnostically relevant anatomic details. CONCLUSIONS: Displaying digital selenium radiographic data sets of thoracic view in two planes on one film presumably does not lead to a loss of diagnostic information. This procedure may help to reduce film costs.

[Color Doppler sonography: non-invasive potential for morphologic and functional vascular diagnosis]. / Farbdopplersonographie: Nicht-invasive Möglichkeiten der morphologischen und funktionellen Gefässdiagnostik.

A linear array colour Doppler sonographic method was used experimentally on a vessel phantom in order to determine flow velocity, and the results were compared with DSA. Both the Doppler and the DSA method showed very good agreement with true velocities (r greater than 0.97). The Doppler method underestimated flow velocity. Early clinical results indicate that colour Doppler sonography is able, at the same time, to demonstrate morphology and function (direction flow and flow velocity) of significant vascular abnormalities by a non-invasive method.

[Gadolinium-DTPA as an oral contrast medium for MR tomography of the abdomen]. / Gadolinium-DTPA als orales Kontrastmittel für die MR-Tomographie des Abdomens.

150 MR examinations of the upper abdomen were carried out after the oral administration of 5 ml/kg body weight of a gadolinium DTPA formulation (1.0 mmol/l, 15 g/l mannitol), with reference to the delineation of the pancrease, the liver and intra-abdominal fat. For comparison, 100 MR examinations without oral opacification of the G.I. tract were evaluated. Contrast administration resulted in a signal-intensive demonstration of the G.I. tract for all measurement sequences. The intraluminal contrast improved the distinction between normal and abnormal structures. T1 and T2 sequences and the demonstration of fat on T2-weighted series. T1-weighted series showed the best diagnostic results. In 25% there was meteorism and diarrhoea within 24 hours of the administration of the oral contrast.

[Interstitial lung diseases. A comparative study between a film-screen combination and a digital storage phosphor technic]. / Interstitielle Lungenerkrankungen. Eine Vergleichsstudie zwischen einer Film-Folien-Kombination und der digitalen Speicherfolien-Technik.

Chest examinations were carried out in 60 individuals using film-screen and digital storage phosphor techniques and identical radiation doses. 29 of these individuals were patients with interstitial pulmonary disease; 31 were normals. Postprocessing of the digital images was carried out with filtering using an unsharp mask and identical parameters for all patients. An ROC analysis using 10 observers showed no significant difference in the evaluation of the interstitial lung disease. Correlation analysis showed a significant positive correlation (p less than 0.001) for the findings in both techniques. Under the present circumstances, film-screen and digital storage phosphor technique are of equal value in the diagnosis of interstitial pulmonary disease.

[Congenital duodenal obstruction in combination with heterotopic gastric mucosa in the gallbladder. Case report and etiology]. / Congenitale Duodenalobstruktion in Kombination mit heterotoper Magenschleimhaut in der Gallenblase. Fallbeschreibung und Atiologie.

A hitherto unique case of ectopic gastric mucosa of the gallbladder in combination with a congenital duodenal stenosis in an young male adult is presented and the etiology of both anomalies is elucidated. While the intestinal obstruction was confirmed prior to the operation, the diagnosis of the gastric heterotopia in the gallbladder has been established, as usually, first by histopathologic examination. Both anomalies required surgical treatment. The long-standing indistinct abdominal complaints of the patient vanished after cholecystectomy and duodenojejunostomy.

[Septic splenic infarction after acute arterial embolism]. / Septischer Milzinfarkt nach akutem arteriellem Verschluss.

HISTORY AND CLINICAL FINDINGS: A 62-year-old woman was admitted because of sudden onset of increasingly severe pain in the left lower leg and foot. She also reported having had diarrhoea for the past few days. INVESTIGATIONS: Physical examination revealed a cold and pale left leg below the knee joint. Peripheral sensory and motor functions were normal. While femoral and popliteal arterial pulses were normally palpable, foot pulses were not felt. Magnetic resonance angiography of the pelvic and leg arteries showed an embolic occlusion of the left popliteal artery extending to the arteries of the lower leg. DIAGNOSIS, TREATMENT AND COURSE: Because of the acute embolic occlusion of the deep femoral and popliteal arteries an embolectomy of the deep and superficial femoral arteries was performed. The source of the emboli had been a free-floating thrombus in the descending aorta. Subsequently a persistent fever and leukocytosis occurred which had been cause by a septic splenic infarction. A conventional splenectomy was done. The postoperative was protracted, because of the development of a pancreatic fistula, which responded to treatment. Anticoagulation treatment started. The patient was finally discharged after more than five weeks. CONCLUSION: After urgent surgical treatment of an acute peripheral arterial occlusion its cause needs to be identified. Transthoracic echocardiography, computed tomography and magnetic resonance angiography are the methods of choice. If there is a floating aortic thrombus further embolizations, including septic splenic emboli may occur.