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The nuclear and non-nuclear industry has produced a considerable amount of low and intermediate-level radioactive wastes during the last decades. The material characterization of waste packages recently became more and more important in order to dispose of these waste packages in a final underground repository. Material characterization remains an indispensable criterion to prevent pollution of the groundwater with toxic materials and is usually required by the national licensing and supervisory authorities. Information on the nature of waste materials can be obtained based on existing documentation or, if the documentation is insufficient, on further destructive or non-destructive analysis. Non-destructive methods are to be preferred to minimize radiation exposures of operating personnel as well as costs. Existing non-destructive techniques (Gamma scanning, X-ray, active/passive neutron counting, muon tomography) do not allow the identification of non-radioactive hazardous substances. An innovative non-destructive measurement system called QUANTOM® (QUantitative ANalysis of TOxic and non-toxic Materials) has been developed. It is based on the prompt and delayed gamma neutron activation analysis (P&DGNAA). This technology is able to identify and quantify the elemental composition (Cd, Cu, B, Pb, Hg, Fe, Al, …) in radioactive packages such as 200-l radioactive drums. This information helps waste producers verify the content of their radioactive wastes, especially regarding the presence of hazardous substances. Different reference materials have been analysed by means of the same technology (P&DGNAA) at the research reactor of BUDAPEST. A comparison of those results for five reference materials is presented. The results show a very good agreement between QUANTOM® and standardized reference analyses.

Im Zuge der Erweiterung des Campus der Technischen Hochschule Dresden in den 1950er Jahren wurden auch südlich des Zelleschen Wegs neue Gebäude für die Lehre und Forschung errichtet. Eine zentrale Grünfläche, im Norden und Süden durch kammartige Gebäudekomplexe begrenzt, wurde stirnseitig durch ein Hörsaalgebäude, den heutigen Trefftz-Bau, abgeschlossen. Die Gestaltung der dortigen Außenanlagen oblag dem von 1952 bis 1968 in Dresden als Professor für Landschaftsarchitektur tätigen Werner Bauch (1912–1983), der in dieser Zeit weite Teile der Freiraumgestaltung des Campus schuf. Mit der dem Beitrag zugrundeliegenden studentischen Arbeit wurde das Ziel verfolgt, aus der Aufarbeitung der Geschichte der Außenanlagen und der anschließenden Analyse des Bestands Schlüsse für eine gartendenkmalpflegerische Zielstellung zu ziehen.

Percutaneous transhepatic portal vein catheterisation with blood sampling from the various areas of drainage, especially the pancreatic veins, was undertaken in seven patients with insulinoma to diagnose its site. In six patients measurement of serum-insulin levels revealed an abrupt rise in the vascular area later found to drain the area of the insulinoma. Insulin measurement in one patient with insulinoma in the head of the pancreas falsely indicated an islet-cell tumour in the region of the tail of the pancreas. C-peptide concentration in serum followed the concentration of insulin, but did not show such a marked rise. The method of percutaneous transhepatic portal vein catheterisation with selective blood sampling for the measurement of hormonal concentration was superior to ultrasound, computer tomography or coeliacography for determining the site of the tumour.

In 17 patients with suspected bleeding in the lower intestinal tract 23 scintigraphic studies were performed with Tc-colloid, followed in each case by visceral-artery angiography. Comparison of the two methods with the final clinical diagnosis indicated that angiography was correct in 6 of 23 examinations (26%), scintigraphy in 12 of 23 (52%). All scintigraphically negative results were negative also angiographically. Noninvasive, relatively unstressful scintigraphy should be performed for immediate diagnosis in any case of acute bleeding. Emergency-type angiography is reasonably performed only if scintigraphy is positive.

Purpose By using localized 1H-MR spectroscopy in the brain of patients with anorexia nervosa we wanted to verify our preliminary results and to look for a reversibility of the metabolic changes under therapy. Methods In 22 patients and 17 healthy volunteers (11 follow-up examinations) single voxel 1H-MR spectroscopy (TE = 50 ms, TM = 30 ms, TR = 1500 ms, voxel (2 cm)3, acq.: 256) was used in two different localizations (thalamus and parieto-occipital region). The first examination of the patients was performed before therapy, the follow-up examination at the end of therapy. Results In both regions of the brain we found a statistically significant elevation of the Cho/Cr-ratio in comparison to normal controls. The follow-up examinations revealed reversibility of the metabolic changes under successful therapy. Conclusions 1H-MR spectroscopy reveals metabolic changes in the brain of patients with anorexia nervosa, which are reversible under successful therapy. These metabolic changes can be conclusively explained using a biochemical model.

PURPOSE The neurophysiological and neuromorphological changes in patients with anorexia nervosa (AN) are well-known but the reason of both is still unknown. We have evaluated the usefulness of hydrogen (H1) magnetic resonance spectroscopy in anorexia nervosa. METHOD We investigated 15 patients with clinically diagnosed AN (ICD F50.0) and 17 controls without eating disorders. The body mass index (BMI) was 15.8 and 21, respectively. The spectroscopy was recorded on two voxels in the parieto-occipital white matter or in the thalamus with a water-suppressed STEAM-sequence. The metabolites were recorded with respect to phosphocreatine (PCr). RESULTS The ratio of NAA/PCr in both voxels were not significantly different when comparing patients vs. controls. Patients showed significantly higher ratios of choline-containing components (Cho) or, respectively Cho/PCr and NAA/PCr in the white matter. Distinct, but not significant differences were detected both for m-Ino and m-Ino/PCr in the parieto-occipital region and for the Cho- and m-Ino contained ratios in the thalamus. CONCLUSION AN is not associated with neuronal damage. The ratio of Cho/PCr and NAA/Cho may reflect the disturbance of membrane-turnover. It is possible that the increase of membrane catabolism leads to a hyperosmolar state. The change of m-Ino/PCr ratio may reflect the regulation of osmolarity.

Electron beam tomography (EBT) has been scientifically evaluated to a much lesser degree for non-cardiac indications than for cardiac purposes. Therefore, four groups of investigators in Berlin (2), Mannheim and Munchen, which were supported by the Deutsche Forschungsgemeinschaft (DFG), included applications outside the heart in their evaluation of EBT technology. EBT has proven useful to look for pulmonary embolism and to assess other vessels (aorta, aortic branches, and intracranial arteries). Imaging of the lung parenchyma benefits from its intrinsic high contrast and from the fast data acquisition of EBT. Limited photon efficiency, higher radiation exposure, increased noise levels and other artifacts, however, markedly reduce the value of EBT for imaging of low contrast objects compared to conventional spiral CT and multislice CT (MSCT), compromising, in particular, the morphologic depiction of parenchymal abdominal organs and the brain. Consequently, scientific studies to further evaluate EBT for scanning of the brain and parenchymal abdominal organs were not pursued. Radiation exposure for non-cardiac EBT studies is up to three times higher than that for respective spiral CT studies, and in children EBT can only be advocated in select cases. Radiation exposure for the various prospectively triggered cardiac examination protocols of EBT is lower than that for conventional coronary angiography. Radiation exposure in cardiac multislice CT exceeds severalfold that of EBT, but the dose efficiency of EBT and MSCT are similar due to higher spatial resolution and less image noise of MSCT. In addition, modifications of MSCT (ECG pulsing) can further reduce radiation exposure to the level of EBT. Technical improvements of the EBT successor scanner "e-Speed" enable faster data acquisition at higher spatial resolution. Within comparative studies, the "e-Speed" will have to prove its value and competitiveness, particularly in comparison with multislice CT. After profound scientific assessment in a multicenter evaluation supported by the Deutsche Forschungsgemeinschaft (DFG) and regardless of the specific suitability of electron beam tomography for various cardiac and some non-cardiac indications, the investigators unanimously find the electron beam tomograph Evolution C150 XP not suitable as a whole body CT scanner.

Electron beam tomography (EBT) directly competes with other non-invasive imaging modalities, such as multislice computed tomography, magnetic resonance imaging, and echocardiography, in the diagnostic assessment of cardiac diseases. EBT is the gold standard for the detection and quantification of coronary calcium as a preclinical sign of coronary artery disease (CAD). Its standardized examination protocols and the broad experience with this method favor EBT. First results with multislice CT indicate that this new technology may be equivalent to EBT for coronary calcium studies. The principal value of CT-based coronary calcium measurements continues to be an issue of controversy amongst radiologists and cardiologists due to lack of prospective randomized trials. Coronary angiography with EBT is characterized by a high negative predictive value and, in addition, may be indicated in some patients with manifest CAD. It remains to be shown whether coronary angiography with multislice CT is reliable and accurate enough to be introduced into the routine work-up, to replace some of the many strictly diagnostic coronary catheterizations in Germany and elsewhere. Assessment of coronary stent patency with EBT is associated with several problems and in our opinion cannot be advocated as a routine procedure. EBT may be recommended for the evaluation of coronary bypasses to look for bypass occlusions and significant stenoses, which, however, can be equally well achieved with multislice CT. Quantification of myocardial perfusion with EBT could not replace MRI or other modalities in this field. EBT has proven to be accurate, reliable and in some instances equivalent to MRI, which is the gold standard for the quantitative and qualitative evaluation of cardiac function. Some disadvantages, not the least of which is the limited distribution of electron beam scanners, favor MRI for functional assessment of the heart.

Hintergrund: Durch die Einfuhrung der ultraschnellen Kernspintomographie (MRT), einschlieslich der Darstellung des hepato-pankreatischen Gangsystems (MRCP) und der 3D-Gefasdarstellung (MR-Angio) haben sich neue diagnostische Moglichkeiten in der Diagnostik von Pankreasveranderungen ergeben. Material und Methode: Wir berichten uber 143 operierte Patienten mit benignen und malignen Pankreaserkrankungen, die ausschlieslich eine MR-Diagnostik praoperativ erhalten haben. Alle radiologischen Befunde wurden intraoperativ uberpruft. Ergebnisse: Es konnte fur die Frage nach der Resektabilitat eine Sensitivitat von 96,0 % bei einer Spezifitat von 89,5 % und bei der Festlegung der Dignitat eine Sensitivitat von 99,1 %, bei einer Spezifitat von 95,2 % mit der MR-Pankreasdiagnostik erreicht werden. Schlussfolgerung: Nach unseren Erfahrungen mit der MR-Pankreasdiagnostik wird sich dieses sichere und komplikationslose diagnostische Verfahren als Standard durchsetzen.

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.

Purpose To evaluate electron beam tomography in the detection of acute pulmonary embolism using a new acquisition protocol. Materials and methods 65 patients underwent electron beam tomography (EBT) and v./p. scintigraphy. According to the inclusion criteria 46 patients participated in the study. Contrast enhancement and detectability of pulmonary arteries were scored on a 4 step scale for image quality. The results of prospective detection of pulmonary embolism were compared for both modalities (blinded reading). "Embolism", "questionable embolism" and "no embolism" were used as categories. Results 22/46 patients (48%) showed acute pulmonary embolism. EBT and scintigraphy were discordant in 24% of patients. In EBT 1 false positive and 1 false negative case occurred, scintigraphy demonstrated 2 false negative and 3 false positive cases. 6/9 patients with questionable findings in scintigraphy were correctly classified by EBT to a category "embolism" or "no embolism" as "suspected embolism", EBT displayed a sensitivity of 96.3% and a specificity of 94.7%. Scintigraphy evidenced a sensitivity of 93.7% and a specificity of 84.4%. Conclusions EBT shows better results than scintigraphy for the detection of acute pulmonary emboli. The evaluated new acquisition protocol for EBT seems to be well suited. High vessel contrast and thin slices allow a reliable detection of segmental and subsegmental pulmonary arteries.

Fragestellung: Im Rahmen einer prospektiven Studie wurden die Befunde initial durchgefuhrter Computertomographien bei Kindern mit schwerem SHT mit den Ergebnissen einer MR-Nachuntersuchung korreliert und zusatzlich eine Evaluation der Haufigkeit und Lokalisation ausschlieslich kernspintomographisch nachweisbarer Lasionen durchgefuhrt. Methodik: 70 Kinder mit initial nach SHT durchgefuhrtem und pathologischem CT wurden im Rahmen eines Follow-up im zeitlichen Abstand von durchschnittlich 3 Jahren kernspintomographisch nachuntersucht. Ergebnisse: Bei 71% der nachuntersuchten Kinder konnten pathologische MRT-Befunde erhoben werden. 43% der Kinder mit einer subduralen Blutung wiesen kortikal, der ehemaligen Blutung anliegende, Parenchymlasionen auf, dagegen zeigten alle 15 Kinder mit Epiduralhamatom an der Stelle der ehemaligen Blutung einen unauffalligen Befund. Alle Kontusionen waren im Follow-up als umschriebene Substanzdefekte nachweisbar. Allerdings wiesen 44% der Kinder Parenchymlasionen auf, die initial und retrospektiv computertomographisch nicht nachweisbar waren. Alle 16 im Corpus callosum gelegenen Herde ware nur mit Hilfe der MRT nachzuweisen. Schlusfolgerung: Zusammengefast zeigt die vorliegende Studie die deutlich hohere Sensitivitat der Kernspintomographie fur nichthamorrhagische Hirnparenchymlasionen und Lasionen im Sinne von „diffusen axonalen Verletzungen” gegenuber der Computertomographie. Bei Kindern mit erlittenem SHT sollte im Verlauf eine kernspintomographische Abklarung durchgefuhrt werden, vor allem bei posttraumatischen neurologischen Auffalligkeiten, die nicht mit Hilfe der initialen computertomographischen Untersuchung erklart werden konnen.

PURPOSE: Evaluation of high-resolution 2D-RARE MRCP in the diagnosis of pancreaticobiliary diseases. MATERIALS AND METHODS: 23 patients with various pancreaticobiliary diseases were evaluated using conventional and high-resolution 2D-RARE sequences. RESULTS: High-resolution RARE MRCP allowed for improved delineation of biliary and pancreatic ducts at the expense of reduced signal-to-noise ratio. Pathological findings were significantly (p < 0.001) better demonstrated with high resolution RARE MRCP (score 1.65 +/- 0.54) as compared to the conventional RARE sequence (score 2.58 +/- 0.62). CONCLUSIONS: High-resolution 2D-RARE-MRCP improves the delineation of biliary and pancreatic ducts. This sequence should replace the conventional 2D-RARE sequence.

In den ersten Stunden nach zerebraler Ischamie ist eine exakte Diagnosestellung haufig schwierig. Die diffusionsgewichtete (DW) Magnetresonanztomographie (MRT) ermoglicht die bildliche Darstellung betroffener Parenchymanteile und quantitative Erfassung der Gewebeveranderungen, noch bevor eindeutige Auffalligkeiten im T2-gewichteten Bild nachweisbar sind. Wir analysierten 105 MRT-Untersuchungen akuter Schlaganfalle (

PURPOSE To prospectively evaluate the role of MRI including MR cholangiopancreatography (MRCP) compared to endoscopic retrograde cholangiopancreatography (ERCP) in the diagnosis of pancreatic cancer. MATERIAL AND METHODS ERCP and MRI including MRCP were performed in 52 patients with suspected pancreatic cancer. MRCP was obtained using a single-shot RARE technique. The results of axial images and MRCP were compared to concurrently performed ERCP examinations. The standards of reference were the surgical and pathological findings, respectively. Image quality of MRCP was assessed using a three-step-score (1 = good, 2 = fair, 3 = nondiagnostic). RESULTS In 88% of the cases the MRCP was of good quality. Only in 4% was MRCP non-diagnostic. The combination of MRI and MRCP showed an overall accuracy of 88%, whereas the overall accuracies of MRCP alone and ERCP were 80%, and 85%, respectively. The positive predictive values of MRI/MRCP, MRCP alone, and ERCP were 91%, 85%, and 88%, respectively. CONCLUSION For the detection of pancreatic cancer MRI including MRCP is comparable to ERCP and can be regarded as the method of choice in patients with suspected pancreatic cancer. ERCP is the procedure of choice in patients with contraindications to MRI and in patients in whom additional therapeutic procedures are performed.

In the last twenty years the basic gastro-intestinal diagnostic procedures have had to record increasing losses. This is why the study of these examinations had becoming more and more endangered. From our experience and from literature review the question arises whether now or in future we can manage without the basic gastrointestinal diagnostic procedures. The answer is that both for efficiency and for costs the continuation of these procedures does not appear acceptable. The preservation of the X-ray techniques of examination should be object of discussion and agreement between radiologists, clinicians, endoscopists, and economically experienced professionals in administration. In order to meet the needs for urgent economic measures in hospitals, the increased use of investigation with water-soluble contrast media seems unavoidable. Therefore the examination techniques should be adjusted and optimised as described.

PURPOSE To evaluate the accuracy of 3D-MRA in preoperative staging in correlation to intraoperative and histological results. METHODS In 30 patients with focal liver lesions axial and coronal MR sequences (T1w-Flash 2D, T2w-TSE unenhanced. T1w-Flash 2D, TRUE FISP contrast-enhanced) as well as coronal breath-hold MRA were performed. The technical parameters of the MRA were as follows; TR/TE 5/2 ms, flip angle 40 degrees, 32-40 partitions with an effective slice thickness of 2-3 mm, acquisition time 26 s, matrix 128 x 256, FOV 320 x 320 to 400 x 400. RESULTS In 23/30 patients liver resection was performed. Correct prediction of segmental localization was achieved in preoperative MRI of 22 patients (98%). The presumed histology was correct in 20/23 cases (87%). The evaluation of the hepatic vascular structures was correctly predicted in all cases. By use of multiplanar reconstructions and single image view of the 3D data base of MRA, additional information could be obtained in 13 patients. CONCLUSIONS Breath-hold 3D-MRA gives certain information on localization and relation of vascular structures to focal hepatic lesions. In presentation of portal venous structures MRA is superior to conventional angiography.

Mit der ultraschnellen kontrastmittelunterstutzten FLASH-3D-MR-Angiographie ist im Vergleich zur konventionellen, nichtkontrastmittelunterstutzten FISP-3D-‘TOF’-MTS-TONE-MR-Angiographie in 83,8% eine ubereinstimmende Darstellung und Einschatzung intrakranieller Gefasprozesse des vertebrobasilaren Stromgebietes mit gleich guter Abbildung der Gefaspathologie innerhalb einer Akquisitionszeit von 35 Sekunden moglich. Bei intakter Blut-Hirn-Schranke und schneller intrakranieller Kontrastmitteltransitzeit mus das Ziel einer kontrastmittelunterstutzten MR-Angiographie des intrakraniellen Stromgebietes eine Optimierung der Untersuchungsparameter mit kurzesten Repetitions- und Echozeiten unter Verbesserung der Ortsauflosung sein. Zusatzlich mus durch Bestimmung der Kontrastmittelanflutungsphase durch eine repetitive Testbolussequenz und standardisierte Injektionsraten mittels maschineller Injektion eine optimale uberlagerungs- und artefaktfreie Gefaskontrastierung des intrakraniellen Stromgebietes gelingen.

Anorexia nervosa is usually associated with a shrinkage of the brain that is at least partially reversible with weight gain. The pathogenesis of this brain abnormality is unclear. The purpose of this study was to investigate potential alterations in localized proton magnetic resonance (1H MR) spectra of anorectic patients immediately after an interval of excessive weight loss. Twelve patients and seventeen control subjects were examined. Water suppressed 1H MR spectra were recorded from two voxels placed in the thalamus and in the parieto-occipital white matter. The spectra of ten patients could be evaluated. Comparing patients and control subjects, significantly higher signal intensity ratios of choline containing compounds (Cho) relative to total creatine (Cr) as well as significantly lower ratios of N-acetyl-aspartate (NAA) relative to Cho were found in the white matter region. We hypothesize that these results indicate an abnormal starvation, associated membrane turnover, which predominantly takes place in the white matter. No evidence for neuronal degeneration was found in the thalamus or in the white matter region.

Purpose To provide methods for stereoscopic visual demonstration from 3D reconstructed MR angiographic images. Methods Stereoscopic viewing can be obtained with pairs of images that are displayed at angles of 15 degrees. Optical devices as stereoscopic binoculars or minor stereoscopes facilitate stereoscopic viewing. The possibility of stereoscopic projections for a larger auditorium is mentioned. Results Using three clinical examples the advantages of stereoscopic display of MR angiograms are demonstrated. Conclusions MR angiography allows stereoscopic viewing with simple methods, like CT- and conventional rotation angiography. This principle, which has been known for 100 years, may thus acquire a new significance.

Ziel: Prospektive Untersuchung der Doppelspiral-CT unter Einsatz eines auf die praoperative Beurteilung des Pankreaskarzinoms abgestimmten Aufnahmeprotokolls. Methodik: Innerhalb eines Jahres wurden 136 Patienten unter der Verdachtsdiagnose einer tumorosen Pankreaslasion an einem Spiral-CT "HiSpeed Advantage" (GE) untersucht und einer prospektiven Befundung anhand eines halbstandardisierten Fragebogens unterzogen. Die Befundsicherung erfolgte mittels Operation, Biopsie oder klinischem Verlauf. Angefertigt wurde eine arterielle Spirale uber der Pankreasloge nach Bolustracking, Injektion von 140 ml Kontrastmittel und Nachinjektion von 30 ml NaCl (Flusrate je 4 ml/Sekunde). Nach einer Verzogerung von 35 Sekunden wurde eine portalvenose Spirale zur Darstellung der Leber angeschlossen. Ergebnisse: Der Tumornachweis gelang mit einer Trefferrate von 92 %, einer Sensitivitat von 98 % und einer Spezifitat von 70 % (6 falsch-positiv, 1 falschnegativ). Bei der lokalen Resektabilitatsbeurteilung wird eine Sensitivitat von 92 %, eine Spezifitat von 88 % und eine Trefferrate von 90 % erreicht (4 falsch-positive, 4 falsch-negative). Die Trefferrate fur den Nachweis einer Infiltration lag bei 94 % fur arterielle und bei 91 % fur venose Gefase, fur den Nachweis der lokalen Organuberschreitung bei 91 % und fur den Nachweis von Lymphknotenmetastasen bei 67 %. Schlusfolgerungen: Das vorgestellte Aufnahmeprotokoll fur die Doppelspiral-CT erlaubt eine zuverlassige praoperative Beurteilung des Pankreaskarzinoms. Purpose: A prospective study was performed to evaluate the accuracy of dual phase helical CT in suspected pancreatic cancer. Methods: Within one year 136 patients underwent helical CT with arterial and portal venous scans after bolus tracking and NaCl bolus injection. Evidence of pancreatic cancer and assessment of resectability were recorded using a standardised protocol. Suspected benign disease was verified by follow-up examination and clinical data, suspected malignant disease was correlated with biopsy or surgery. Results: For the detection of tumor the overall concordance was 92 %, the sensitivity 98 % and the specificity 70 % (6 false positve, 1 false negative). Resectability was correctly assessed in 90 % with a sensitivity of 92 % and a specificity of 88 % (4 false positive, 4 false negative). Vascular invasion was detected correctly in 91 % (veins) -94 % (arteries), lymph node invasion in 67 % and liver metastasis in 94 %. Conclusion: Dual phase helical CT is a very reliable tool in the assessment of resectability in pancreatic cancer.

PURPOSE: To evaluate the use of dual-phase helical computed tomography (CT) (with or without CT angiography) to assess resectability in patients suspected to have pancreatic cancer. MATERIALS AND METHODS: Tumor resectability was prospectively evaluated in 89 patients who later underwent surgery for suspected pancreatic cancer. Helical CT scans were obtained in the vascular phase and a phase of maximal hepatic enhancement. CT angiograms were produced with multiprojection volume reconstruction and maximum-intensity projection. CT results were correlated with surgical and histopathologic results. RESULTS: Helical CT allowed detection of pancreatic cancer in 74 of 76 cases (97%). There were six false-positive results (positive predictive value, 92%). For prediction of irresectability, helical CT had an accuracy of 91%, negative predictive value of 79%, and sensitivity of 91%. Helical CT allowed detection of liver metastases in 21 of 28 cases (75%), nodal involvement in 13 of 24 cases (54%), and vascular invasion in 35 of 40 cases (88%). CT angiography demonstrated 30 of the 35 cases of vascular invasion detected with helical CT (86%). CONCLUSION: Use of dual-phase helical CT improves prediction of resectability in patients with pancreatic cancer. CT angiography cannot show all of the findings seen on helical scans.

Ziel: Einsatz der individuellen Bolustriggerung mit Nachinjektion eines NaCl-Bolus zur Optimierung der Injektionsparameter bei der Spiral-CT des Abdomens. Untersuchung der aus der Bolustriggerung resultierenden diagnostischen Bildqualitat im Abdomen. Methoden: Drei nicht vorselektionierte Patientenkollektive wurden mit der biphasischen Spiral-CT (HiSpeed Advantage, Fa. GE) untersucht. Analysiert wurde der Einflus des NaCl-Bolus auf die Dauer der maximalen aortalen Kontrastierung. Mit Hilfe einer dreistufigen Bewertungsskala erfolgte die Beurteilung der Parenchym- und Gefaskontrastierung im Abdomen. Zusatzlich wurde der Einflus von Korpermassenindex, Injektionsgeschwindigkeit und Kontrastmittelvolumen auf die Kontrastierung evaluiert. Ergebnisse: Die Nachinjektion von NaCl verlangerte das Plateau der aortalen Kontrastierung signifikant. Optimale Bildqualitat fur Pankreas und Abdominalarterien wurde in der arteriellen Phase, fur Leber, Milz, Nieren und Abdominalvenen in der portalvenosen Phase erzielt. Korpermassenindex, Injektionsgeschwindigkeit und Kontrastmittelvolumen hatten einen signifikanten Einflus auf die aus der Bolustriggerung resultierenden Zeitintervalle fur die arterielle Phase der Spiral-CT-Untersuchung. Schlusfolgerung: Die individuelle Bolustriggerung mit Nachinjektion von 20 ml NaCl-Bolus verbessert die intravenose Kontrastmittelgabe. Purpose: To optimise injection parameters in helical CT of the abdomen with individual bolus tracking and subsequent NaCl bolus injection. To investigate the effect of bolus tracking on image quality in the abdomen. Methods: Patients were randomised into three examination protocols and underwent biphasic helical CT (HiSpeed Advantage, CE). The effect of NaCl bolus on duration of aortic enhancement was investigated. Contrast enhancement in parenchyma and vessels was examined. The influence of body mass index, injection flow and contrast material volume on enhancement was evaluated. Results: Subsequent injection of NaCl provided significant extension of contrast enhancement in the aorta. Optimal image quality for pancreas and abdominal arteries was achieved in the arterial phase and for liver, spleen, kidneys and abdominal veins in the portal venous phase. Body mass index, injection flow and contrast material volume showed a significant influence on the time intervals resulting from bolus tracking. Conclusion: Individual bolus tracking with subsequent injection of 20 ml NaCl bolus optimises intravenous contrast application.

PURPOSE The purpose of this study was to assess the clinical value of HRCT of the lung in patients with known HIV-infection and acute lung disease. In a prospective study a HRCT was performed in 31 patients infected with the HIV-1 virus, mainly stage C (CDC), who had acute pulmonary symptoms. Precondition for the HRCT examination was a normal or non-specific chest radiograph. A provoked sputum as well as bronchoscopy with bronchoalveolar lavage and/or transbronchial biopsy were performed concurrently. In 24 out of 31 cases a pathogenic organism was identified. 19 of these 24 patients showed abnormal HRCT findings. The most frequent pathogenic organism was Pneumocystis carinii (n = 12). 9 out of these 12 patients (75%) showed pathological HRCT findings consisting of ground-glass opacity. Specific patterns of attenuation could not be worked out except for Pneumocystis carinii infection. Compared to bronchoalveolar lavage, the diagnostic value of HRCT is inferior; it is however helpful in the early stage of disease, when the pathogenic organism has not yet been identified, HRCT may demonstrate parenchymal abnormalities in patients with normal radiographic findings. Compared to bronchoalveolar lavage and induced sputum, HRCT can provide conclusive results within a short time.

Different concepts and applications of teleradiology systems have been realised. However, their cost-effectiveness is still questionable. Therefore, a cost-benefit anylsis of three different scenarios of the new teleradiology system Kamedin (Kooperatives Arbeiten und rechnergestutzte Medizinische Diagnostik auf innovativen Netzen der Deutschen Telekom) was performed. Methods: CT examinations were transmitted from an Advantage Windows (GE) workstation to a Kamedin workstation using DICOM 3 protocol. Afterwards a teleconference was established with a Kamedin workstation in the intensive care unit within the hospital via FDDI/Ethernet, with an external workstation in a radiology department 6 km away via ISDN and with a Kamedin PC located with radiologist on duty 22 km away via ISDN. On average, 36 CT slices per patient were transferred. A break-even analysis was performed with respect to costs of hardware, software, support, use of ISDN and staff, as well as benefits like the decrease in transportation or film documentation costs. Results: Owing to the different reductions in transportation costs, two applications (intensive care unit and external PC) showed a break-even of 1817 and 528 teleconferences/year, respectively. Further optimisation of cost-effectiveness is possible on condition that existing hardware can be used and an automatic data transfer without staff control is available. When all optimisation factors were combined, the break-even decreased to a minimum of 167 and 77 teleconferences/year, respectively. Conclusion: Teleconferences with high image quality can be set up between workstations and PCs using the Kamedin system. Depending on the possible decrease in transportation costs, teleconferencing is cost-effective under certain conditions. Teleradiology has additional advantages, such as the acceleration and optimisation of patient management.

Specific radiological requirements have to be considered for the realization of telemedicine. In this article the goals and requirements for an extensive introduction of teleradiology will be defined from the radiological user's point of view. Necessary medical, legal and professional prerequisites for teleradiology are presented. Essential requirements, such as data security, maintenance of personal rights and standardization, 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, such as acknowledgement of electronic documentation, reimbursement of teleradiology and liability, must be clarified. Legal advice and the observance of quality guidelines are recommended.

Die nichtinvasive Diagnostik von Stenosen der A. cerebri media (ACM) erfolgt mittels transkraniellem Doppler (TCD) und Magnetresonanzangiographie (MRA). Da die kurze Untersuchungszeit der Spiral-CT-Angiographie (CTA) ein schnelles Notfallmanagement von Patienten mit akuter Verschlussymptomatik erlaubt, wurde die Nachweisbarkeit von Lumeneinengungen der ACM an 23 in MRA und TCD gesicherten Stenosen untersucht. Fur die CTA wurde eine bolusgetriggerte Injektion von 70 ml KM mit 40 ml NaCl-Bolus, eine Detektorbreite von 1 mm, ein pitch von 1,5 und ein Rekonstruktionsintervall von 1 mm eingesetzt. Die Darstellung des Angiogramms erfolgte als MIP und als MPVR. Gegenuber MRA und TCD wurden durch die CTA 14 Stenosen gleich und 9 Stenosen niedriger klassifiziert. Eine Uberschatzung des Stenosegrades durch die CTA kam nicht vor. Bei gleichwertiger Stenoseklassifikation zeigte die MPVR gegenuber der MIP eine bessere Abbildungsqualitat. Die Ergebnisse sprechen dafur, das mit der CTA mittel- und hochgradige Stenosen der ACM sicher und schnell erfast werden konnen.

PURPOSE The development of a CD-ROM database for continuous acquisition and archiving of interesting radiologic cases is described. As a pilot study radiologic images of focal lesions of the liver were collected. METHODS The database runs on a PC (80486 DX2, 66 MHz, 16 MB RAM), which is connected to the clinic network, a high quality x-ray scanner and a CD-ROM writer. Radiologic images can be inserted into the database either by scanner or by image transfer via network. The database is designed using Access 2.0. Well documented cases were chosen retrospectively, manipulated and archived. RESULTS 308 images of 12 focal lesions with a capacity of 802 MB were stored on CD-ROM. Per case a storage capacity of 40-75 MB is necessary for image raw material, 15-25 MB are necessary for the postprocessed data. Spatial resolution is 190 dpi (3000 pixel/40 cm). Clinical data, radiological diagnosis coded by modified ACR index and a compressed icon of the images are stored on PC, the image data are stored on CD-ROM. 2.5 hours per case are needed for the complete acquisition, manipulation and archiving procedure, but improved hardware configuration can reduce the time significantly. CONCLUSION The described database allows continuous archiving of interesting radiologic cases on PC. ACR index is suited for a quick search of a specific combination of radiologic images and diagnosis from different modalities.

PURPOSE In a retrospective analysis the diagnostic value of two scintigraphic methods was compared with each other. METHOD 104 patients with acute or intermittent gastrointestinal haemorrhage were examined with 121 scintigraphic studies. We compared scintigraphic results with surgical findings, endoscopic results or final clinical diagnosis. We used two scintigraphic methods, colloid scintigraphy and in vivo/vitro red blood cell scintigraphy. RESULTS Our scintigraphic findings reached a sensitivity of 72% and a specificity of 100%. We calculated a sensitivity of 68% for colloid scintigraphy and a sensitivity of 79% for red blood cell scintigraphy. The correct localisation of bleeding was successful in 52 (98%) cases. CONCLUSIONS Our results demonstrate that red blood cell scintigraphy is the method of choice in detecting intermittent gastrointestinal hemorrhage. We believe that with new preparation kits for in vivo labelling red blood cell scintigraphy will become seriously competitive for the colloid scintigraphic method.

AIMS Functional magnetic resonance imaging was used in conjunction with a letter detection task for the study of working memory in 16 normal subjects. Because of movement artifacts, data from only 9 subjects were analysed. METHODS In the activation task, subjects responded by pressing a button whenever any presented letter was the same as the second last in the sequence. In the control condition, the subjects had to respond to a fixed letter. Hence, the activation condition and the control condition differed only subjectively, i.e., regarding the task demand, whereas the stimuli and the type and frequency of response were identical. RESULTS The activation condition produced significant activation in the dorsolateral prefrontal cortex (Brodmann's areas 10, 46, and 9). CONCLUSIONS In contrast to experimental tasks previously used rather extensively to study the prefrontal cortex, the present paradigm is characterized by its simplicity, interpretability, and its ties to known neurophysiology of the frontal cortex.

Eight patients with a prominent occipitotemporal vein on MR imaging, and ipsilateral temporal lobe epilepsy are reported. The ages of the patients ranged from 2 months to 12 yr. There were five males and three females. Abnormal electroencephalographic (EEG) findings were evident in all the patients, and they had focal seizures. MR images revealed prominent (4 mm or more in width) occipitotemporal veins in the ipsilateral sides, and otherwise unremarkable findings. Three similar patients have previously been reported in the literature. We speculate that a prominent occipitotemporal vein may represent a consequence or a cause of a certain type of temporal lope epilepsy. Further clinicoradiologic studies are required to clarify the question raised by these observations.

A method is presented that enables the use of (static) informations from magnetic resonance imaging (MRI) for (dynamic) biomechanical analysis. Using a specially developed software MRI pixel matrices are colour-coded and--according to the principle of same density--line data are created. After sectional attribution of the resulting polygons a three-dimensional mesh of so-called finite elements is created which can then be used in deformation analysis. This method is exemplified by a project dealing with the simulation of birth mechanics, which is finally aimed at validating the results from radiologic pelvimetry. First analyses show that even under foetal head moulding conditions, being considered as normal, such sensitive structures as the cerebellum, brain stem as well as the ventricles with the plexus chorioidei are to be found within the maximum isobars within a range of 104-140 N(10.6-14.3 kp).

The important dimensions of pelvimetry were evaluated from 467 CT studies of the pelvis by trigonometric deduction. The age of the women was between 18 and 88 years. In addition to the diameters, which are routinely used for pelvimetry, transverse and sagittal diameters, pelvic angles and areas of pelvic planes were calculated. On condition that the pelvic dimensions do not depend on age the parameters can be regarded as representative of sexual maturity. 5 parameters showed highly significant and 7 parameters showed significant differences between the age-classes 1901-1920 and 1950-1971. An increase of pelvic dimensions (1950-1971) was found at the planes of the pelvic inlet and outlet in contrast to the dimensions of the pelvic center. The results confirm the importance of the bispinous diameter for pelvimetry as well as the demand for a revision of the standard values of the first half of the century.

Since April 1990, chest radiographs in the Mannheim clinic have been performed with a slit technique (Kodak AMBER System). In this study, image quality from conventional film/screen combination and from storage phosphor radiography was compared with that from the AMBER system. Phantoms were used to measure spatial resolution and to determine the detectability of nodules. Image quality affecting various structures within the thorax was evaluated on 200 p.a. and 48 lateral radiographs by three radiologists from Mannheim and four from Berlin. In the retrocardiac, retrodiaphragmatic, mediastinal and peripheral portions the best image quality was obtained by film/screen with the AMBER system. Compared with conventional film/screen images, there was no improvement from the AMBER system within the lung parenchyma. The use of storage phosphor plates with the AMBER system did not lead to any further improvement in image quality.

Paramagnetic contrast agents produce local magnetic field inhomogeneity when they pass through the cerebrovascular system. This effect can be monitored with T2*-weighted gradient echo images, which show transient signal loss, while a bolus of GdDTPA is passing through the brain tissue. This signal loss is correlated to the local cerebral tissue perfusion and the local cerebral blood volume. In a prospective study 10 volunteers and 14 patients with cerebral infarcts and brain tumours were examined. After bolus application of GdDTPA a dynamic series of rapid T2*-weighted gradient echo images were recorded, and the local dynamics of contrast flow in brain tissue was examined. From the series of images, local changes in signal intensity were calculated pixel by pixel and presented as parameter images. By this method, infarcted areas and brain tumours can be distinguished from normal tissue by their contrast flow dynamics. The abnormal contrast dynamics depend on changes in local tissue perfusion and alterations in local blood volume. The separation of the influence of both parameters however is still an unsolved problem.

MR angiography (MRA) combined with selective saturation techniques has proved to be a reliable method for the determination of flow direction and vascular supply at the level of the circle of Willis. We describe its application to the vertebrobasilar system (VBS) in ten volunteers and five patients with abnormal findings. In one patient with postsurgical stenosis of the brachiocephalic artery, reverse flow of the vertebral artery (VA) was demonstrated. Collateral blood flow from the anterior circulation over the posterior communicating arteries was shown in three patients with bilateral vertebral or proximal basilar artery occlusion. Due to increase of pressure during contrast injection into the contralateral VA, DSA showed reverse flow of a dissected VA in one patient. MR flow determination as well as TCD proved antegrade flow. All results correlated with both DSA and transcranial Doppler (TCD). The technique is little time consuming and is a promising add-on examination to conventional and MRA imaging of the VBS.

35 patients with brachial and/or cerebral ischemia underwent 37 PTA's. Indications for PTA were stenosis (n = 31) or occlusion (n = 1) of the subclavian artery, stenosis of the brachiocephalic trunk (n = 2), stenosis of the axillary artery (n = 2) and stenosis of the brachial artery (n = 1). 23 patients demonstrated a subclavian steal phenomenon. However, the minority of patients (n = 10) presented with neurologic symptoms, which could be provoked by brachial exercise in only 3 patients. 7 of the 10 patients with cerebral ischaemia demonstrated additional significant stenosis of the extracranial arteries. The technical success rate for PTA was 89.2%. Two patients showed relapse of the stenosis. The clinical success rate regarding brachial ischaemia was 94.4% (follow-up: 6-37 months). Neurologic symptoms disappeared after treatment in 72.7%. Minor complications without clinical sequelae occurred in 8.6%.

The clinical value and the imaging characteristics of digital radiography systems (image intensifier (I.I.) radiography: Polytron/Siemens, storage phosphor radiography: PCR/Philipps) in skeletal imaging were compared with film-screen radiography and 100 mm technique. The influence of spatial and contrast resolution, entrance dose and detectability of lytic, osteoblastic and cortical lesions were studied as well as the images of 25 parallel examined patients. Only with the small image intensifier (diameter 14 cm) the quality of 100 mm technique and digital I.I. radiography was equivalent to storage phosphor and film-screen radiography. Storage phosphor radiography seems to be better qualified than I.I. radiography to replace conventional techniques in skeletal imaging.

With approximately 150 reported cases, fistulas between the abdominal aorta and inferior vena cava are rare. Preoperative clinical diagnosis of aortocaval fistula is difficult because the classical triad of abdominal pain, pulsatile abdominal mass, and abdominal machinery-like bruit may be absent in up to 50 % of patients. We report a case of aortocaval fistula complicating abdominal aortic aneurysm which was diagnosed preoperatively using breath-hold gadolinium-enhanced three-dimensional MR angiography.

A questionnaire was sent by mail to 4400 radiologists (i.e. to at least 1000 radiological institutions). The response rate was about 5%. The results showed that 47% of respondents felt well informed about teleradiology, 49% not enough and 3% not at all. Image and report transfer as well as interfaces to reference databases, educational applications, technical quality surveillance and product support (maintenance) were considered to be increasingly important areas. Smaller institutions (1–3 doctors) judged expert consultation as more important than bigger institutions. Standardization, system stability and data security were demanded as well as guidelines, for example concerning the linking of report and image, correct documentation and required image quality. Technically most demands can be fulfilled today but this technology is not yet commonly included in teleradiology systems.