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Background:  Transcatheter aortic valve implantation (TAVI) has evolved into an alternative procedure to surgical valve replacement for high-risk patients with aortic valve stenosis. Despite technical innovations, there is still a risk of complications during and after the intervention. After a TAVI procedure, ECG-gated multidetector computed tomography (MDCT) plays an important role in the early diagnosis of local complications. In this article, we explain for the first time how the technical acquisition of MDCT in the region of the aortic root is performed as post-interventional control of the TAVI prosthesis. In the second part normal post-interventional findings of different prosthetic valves as well as classic and uncommon complications in the implant area will be illustrated in several case studies., Methods:  In this review the current literature from PubMed about ECG-gated MDCT after TAVI is summarized and structured. It is supplemented by several case studies from our institution., Results and Conclusion:  Using retrospectively ECG-gated MDCT, an aortic valve prosthesis after TAVI can be visualized with high spatial resolution in several phases of the cardiac cycle. Images of the implanted aortic valve at all time points of the cardiac cycle enable a functional analysis of prosthetic leaflets similar to echocardiography. MDCT is superior to transthoracic echocardiography with respect to the direct detection of prosthetic leaflet thrombosis. The position of the device in relation to the coronary ostia and correct unfolding of the stent frame need to be evaluated. There are different types of stents carrying the valve leaflets with distinct ideal positions. Any stent should cover the left ventricular outflow tract (LVOT) along its whole circumference. Life-threatening complications in the implant area, such as annulus rupture, can be diagnosed reliably with CT., Key Points:   · ECG-gated multidetector CT (MDCT) after transcatheter aortic valve implantation (TAVI) can provide early detection of postinterventional complications of the prosthetic valve and the aortic root.. · MDCT is superior to echocardiography with respect to the direct detection of prosthetic leaflet thrombosis.. · MDCT can also reveal hypokinesia of the thrombotic valve leaflets.. · Correct position of the device und unfolding of the stent frame differ according to the type of prosthesis.. · The integrity of the native aortic root should be carefully assessed.., Citation Format: · Soschynski M, Capilli F, Ruile P et al. Post-TAVI Follow-Up with MDCT of the Valve Prosthesis: Technical Application, Regular Findings and Typical Local Post-Interventional Complications. Fortschr Röntgenstr 2018; 190: 521 - 530., Competing Interests: Disclosure The authors report no conflicts of interest in this work., (© Georg Thieme Verlag KG Stuttgart · New York.)

Purpose:  To compare ratings regarding the depiction, diagnostic accuracy and lesion characterization of conventional synthesized mammography (SM), multiple angulated mammography reconstructions (INSIGHT3D), and standard stack reconstructions in digital breast tomosynthesis for microcalcifications., Materials and Methods:  This is a retrospective, multicase, multireader study. We included patients with digital breast tomosynthesis (DBT), microcalcifications and histology over a period of four months in our institution and the same number of normal cases. Three radiologists, who were blinded to patient data, independently rated the depiction, distribution, morphology and BI-RADS score of microcalcifications in SM, INSIGHT3D and standard stack reconstructions. Deidentified images were presented in random order. Reading time was measured. Friedman and post hoc Nemenyi tests, Cochrane's Q and post hoc Wilcoxon signed rank tests, Fleiss' kappa and receiver operating characteristics were used for statistical analysis., Results:  We included 41 histopathologically proven and 41 normal cases. Depiction of microcalcifications was rated better in INSIGHT3D than in SM and better in stack reconstructions than in INSIGHT3D and SM (P < 0.001). The reading time was lower in SM and INSIGHT3D compared to stack reconstructions (P < 0.001). The diagnostic accuracy and inter-rater correlation were comparable between all tested modes of reconstruction., Conclusions:  INSIGHT3D has higher ratings regarding the depiction of microcalcifications compared to SM while maintaining a short reading time. Our preliminary assessment suggests that INSIGHT3D provides added value to SM., Key Points:   · INSIGHT3D depicts microcalcifications better than synthesized mammography while maintaining a low reading time.. · The diagnostic accuracy and inter-rater correlation were comparable between INSIGHT3D and synthesized mammography.. · INSIGHT3D may be a potential successor to synthesized mammography.., Citation Format: · Neubauer J, Neubauer C, Wicklein J et al. Multiple Angulated Mammography Reconstructions in Digital Breast Tomosynthesis for the Diagnosis of Microcalcifications - Added Value to Standard Stack Reconstructions and Synthesized Mammography. Fortschr Röntgenstr 2018; DOI: 10.1055/s-0044-100726., Competing Interests: J. W. and T. M. are Siemens Healthcare GmbH staff members. All other authors declared that they have no conflict of interest., (© Georg Thieme Verlag KG Stuttgart · New York.)

Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Purpose: Comparison of radiation dose of cone beam computed tomography (CBCT) and multidetector computed tomography (MDCT) in examinations of the hand., Materials and Methods: Dose calculations were carried out by means of Monte Carlo simulations in MDCT and CBCT. A corpse hand was examined in a 320-row MDCT scanner and a dedicated extremities CBCT scanner with standard protocols and multiple low-dose protocols. The image quality of the examinations was evaluated by 5 investigators using a Likert scale from 1 (very good) to 5 (very poor) regarding depiction of cortical bone, cancellous bone, joint surfaces, soft tissues and artifacts. For a sum of ratings of all structures < 50 a good overall image quality was expected. The studies with at least good overall image quality were compared with respect to the dose., Results: The dose of the standard examination was 13.21 (12.96 to 13.46 CI) mGy in MDCT and 7.15 (6.99 to 7.30 CI) mGy in CBCT. The lowest dose in a study with good overall image quality was 4.54 (4.43 to 4.64 CI) mGy in MDCT and 5.72 (5.59 to 5.85 CI) mGy in CBCT., Conclusion: Although the dose of the standard protocols in the CBCT is lower than in the MDCT, the MDCT can realize a good overall image quality at a lower dose than the CBCT. Dose optimization of CT examination protocols for the hand is useful in both modalities, the MDCT has an even greater potential for optimization., Key Points: • Low dose examinations of the hand are feasible in CBCT and MDCT.• In default settings CBCT has a lower dose than MDCT.• MDCT enables a good image quality at a lower dose than CBCT. Citation Format: • Neubauer J, Neubauer C, Gerstmair A et al. Comparison of the Radiation Dose from Cone Beam Computed Tomography and Multidetector Computed Tomography in Examinations of the Hand. Fortschr Röntgenstr 2016; 188: 488 - 493., (© Georg Thieme Verlag KG Stuttgart · New York.)

This publication outlines the "medical research" licensing procedure as specified in the amendment of the German Radiation Protection Ordinance of November 1, 2011. The general licensing requirements for the use of radiation have not been changed by the amendment. Three so-called use restrictions (i. e., dose limits of 10 mSv and 20 mSv, age limit of 50 years) have been modified. They will only apply to healthy volunteers in the future. In addition, there are considerable simplifications with respect to applications and licensing procedures of the Federal Office for Radiation Protection (Bundesamt für Strahlenschutz, BfS) regarding the use of radiation in the newly introduced "accompanying diagnostics" ("Begleitdiagnostik") case group. The newly established, independent panel of experts at the German Radiological Society (Deutsche Röntgengesellschaft, DRG) may provide essential support to principal investigators, qualified physicians and sponsors for differentiating between "medical research" and "health care", the latter not being subject to licensing. An expert statement will be issued by the DRG within four weeks of an inquiry. This consulting service is subject to confidentiality, and is free of charge for inquirers and without any commitment., (© Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: To discuss the juridical basis for CT examinations of cocaine body packers and to evaluate the clinical implementation of a tube current reduction-based low-dose CT protocol., Materials and Methods: A literature search was performed to discuss the legal basis regarding the problem, the procedures, the potential harm and the proportionality. Retrospective evaluation of 8 patients who had undergone a low-dose CT scan (body mass index < 25 kg/m(2) 30 mAs; > 25 kg/m(2) 60 mAs) during the time period from February until October 2009 in order to exclude or to assess remaining cocaine body packs was approved by the institutional review board. The detectability and condition of the body packs were analyzed. Effective doses were calculated., Results: German jurisdiction does not distinguish between plain film X-ray and CT examinations. Both plain film X-ray and CT examination require a judicial warrant. However, examination results might still remain valid if a warrant was not requested. In 8 examinations (30 mAs n = 3, 60 mAs n = 5, mean BMI 25.9 ± 3.2) a total of 34 body packs were correctly identified. The mean density of the body packs was 74.4 ± 31.9 HU (range 17-154 HU) with a cocaine content between 22.5% and 72.8%. The mean estimated radiation dose was 2.23 ± 0.72 mSv., Conclusion: Although medical legal aspects do not specify the diagnostic procedure to be performed, the high diagnostic accuracy and applied radiation dose reduction could establish low-dose CT as the method of choice for detecting cocaine body packs, thereby potentially avoiding future legal problems., (© Georg Thieme Verlag KG Stuttgart · New York.)

CT angiography is the imaging modality of choice for the pre- and postsurgical evaluation of patients with pathologies of the thoracic aorta. The purpose of this review is to familiarize the reader with the technical principle, recent technical developments and requirements for specific examination protocols and image interpretation, and to highlight common pathologies and findings., (© Georg Thieme Verlag KG Stuttgart · New York.)

Magnetic resonance imaging (MRI) with a continuously moving table (CMT) represents a novel method allowing for the seamless acquisition of an extended field-of-view in the z-direction. One option to realize CMT MRI from a technical point of view is based on very fast sequences like echo planar imaging (EPI). Consequently, table translation for signal sampling and image reconstruction can be neglected. The acquisition of different contrasts, however, necessitates table motion correction, either during acquisition or via post-processing. First clinical studies applying fast steady-state imaging already yielded promising results with respect to metastasis detection. Nevertheless, additional equipment has to be installed for table motion and position tracking. In contrast, the subsequently developed sliding multislice (SMS) technique can be implemented without any additional hardware. In clinical studies, the achievable image quality corresponds to stationary sequences. Additionally, the use of SMS for the detection of pulmonary and abdominal metastases appears to be comparable to computed tomography (CT). Due to the relatively short examination times, CMT MRI can be integrated into highly specialized stationary imaging protocols, thus increasing the possibility to combine local staging with thoracoabdominal metastasis screening within one examination. New contrasts like diffusion-weighted imaging (DWI) or Dixon techniques as well as improved workflow including breathing motion compensation and intuitive scout acquisition have already been proposed and will further expand the clinical applications of this technique., (© Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: Evaluation of the impact of a new, dynamic computer-aided quality manual application (QMA) regarding the acceptance and efficiency of a quality management system (QMS) according to DIN EN ISO 9001:2000., Materials and Method: The QMA combines static pages of HTML with active content generated from an underlying database. Through user access rights, a hierarchy is defined to create and administer quality documents. Document workflow, feedback management and employee survey were analyzed to compare the performance of the new QMH with the formerly used static version., Results: Integration of a document editor and automated document re-approval accelerated the document process by an average of 10 min. In spite of an increase of the yearly document changes of 60%, the administration effort was reduced by approximately 160 h. Integration of the feedback management system into the QMA decreased handling time from an average of 16.5 to 3.4 days. Simultaneously the number of feedback messages increased from 160 in 2005 to 306 in 2006. Employee satisfaction was raised (old: 3.19+/-1.02, new: 1.91+/-0.8). The number of users who partook in the QMA more than once a week also increased from 29.5% to 60%., Conclusion: The computer-aided quality manual application constitutes the basis for the success of our QMS. The possibility to actively participate in the quality management process has led to broad acceptance and usage by the employees. The administration effort was able to be tremendously decreased as compared to conventional QMS.

Giant cell (temporal) arteritis is a diagnostic challenge. Blindness is a dreaded complication, especially if high-dose steroid treatment is delayed. With an optimized MR protocol, noninvasive diagnosis of giant cell arteritis is facilitated. Submillimeter in-plane resolution makes it possible to distinguish healthy segments from inflamed segments. The lumen and arterial wall can be depicted in high detail. Post-contrast high-resolution MRI visualizes the superficial cranial arteries bilaterally and simultaneously, allowing assessment of the cranial involvement pattern. In combination with MR angiography of the aortic arch and supra-aortic arteries, the extracranial involvement pattern can be demonstrated in a single comprehensive MR examination assessing the cranial, cervical and thoracic vasculature. Good diagnostic image quality can be achieved at 1.5 Tesla and at 3 Tesla. However, due to higher signal-to-noise ratios, image quality seems to be superior at 3 Tesla. Over the course of successful long-term treatment, MR signs of mural inflammation decrease significantly and eventually vanish entirely. In contrast to color-coded Duplex sonography, which is a comparatively cost-efficient imaging modality, acquisition of high-resolution MRI is almost independent of the investigator's expertise. Compared to positron emission tomography with 18F-fluoro-2-deoxy-D-glucose, which is a very sensitive whole-body screening tool for detecting extracranial involvement of large vessel vasculitis, MRI allows visualization and assessment of both the superficial cranial arteries in high detail and the extracranial large artery involvement in the same investigation.

Modern phase contrast MR imaging at 3 Tesla allows the depiction of 3D morphology as well as the acquisition of time-resolved blood flow velocities in 3 directions. In combination with state-of-the-art visualization and data processing software, the qualitative and quantitative analysis of hemodynamic changes associated with vascular pathologies is possible. The 4D nature of the acquired data permits free orientation within the vascular system of interest and offers the opportunity to quantify blood flow and derived vessel wall parameters at any desired location within the data volume without being dependent on predefined 2D slices. The technique has the potential of overcoming the limitations of current diagnostic strategies and of implementing new diagnostic parameters. In light of the recent discussions regarding the influence of the wall shear stress and the oscillatory shear index on the genesis of arteriosclerosis and dilatative vascular processes, flow-sensitive 4D MRI may provide the missing diagnostic link. Instead of relying on experience-based parameters such as aneurysm size, new hemodynamic considerations can deepen our understanding of vascular pathologies. This overview reviews the underlying methodology at 3T, the literature on time-resolved 3D MR velocity mapping, and presents case examples. By presenting the pre- and postoperative assessment of hemodynamics in a thoracic aortic aneurysm and the detailed analysis of blood flow in a patient with coarctation we underline the potential of time-resolved 3D phase contrast MR at 3T for hemodynamic assessment of vascular pathologies, especially in the thoracic aorta.

Preoperative portal vein embolization (PVE) is increasingly used for operative treatment of patients scheduled to undergo liver resection when the volume of the future remnant liver appears to be insufficient. Portal vein embolization should be considered when the prospective postoperative liver volume is less than 20 % or less than 40 % in patients with known liver cirrhosis. Our own results (n = 28) demonstrated an average volume increase in segments II and III of 280 +/- 95 ml to 420 +/- 98 ml within 6 weeks after selective percutaneous- transhepatic embolization of the portal vein branches (IV)-V-VIII. Thus, an expanded right resection of the liver could be performed in all patients without major complications. None of the patients suffered from clinically relevant liver insufficiency within the first few postoperative months.

MRI is accepted as one of the major diagnostic tools for the detection of anorectal fistulas and abscesses. Noninvasiveness and high accuracy are advantageous hallmarks of this technique. In general, the purpose of imaging anal fistulas is to reduce the risk of recurrence, incontinence and non-healing. To achieve these goals, the applied method must provide the proctologist with detailed information. In this context, MRI acts as a guide for surgeons to accurately plan fistula operations. Another aspect is the follow-up of conservatively treated patients with fistulizing Crohn's disease. In 2000, subtraction MR fistulography was introduced as new imaging technique. This review provides an overview of the entire spectrum of diagnostic modalities for anorectal fistulas with emphasis on subtraction MR fistulography.

In large installations of a Picture Archiving and Communication System (PACS), data protection becomes an issue. Above all, not every employee should have access to all data stored in the system. At the Freiburg University Hospital, we developed a concept of dynamic assignment of authorization, assuring that every physician is authorized to the data of all patients under his care. We describe the technical implementation of data protection developed for the integration of PACS and electronic patient records in Freiburg. The system was installed in January 2001 and the experience of its two years in operation is reported.

Purpose: Evaluation of image quality of paper prints in routine CT investigations., Method: The image quality of paper prints from 104 CT scans of daily routine investigations was analysed by three observer three observers according to a five-point ranking scale for contrast, grey level, spatial resolution, and subjective confidence in correct evaluation. Each study was rated "acceptable" or "not acceptable for documentation"., Results: In 312 ratings the mean grade for contrast was 2.7, for grey levels 3.2, and for spatial resolution 3.3. Grades ranged from 1 = very good to 5 = insufficient. Subjective confidence in correct evaluation was rated as "certain" in 77.4 %, "likely" in 18.4 % and "impossible to evaluate" in 4.2 % of cases. 93.7 % of printed CT images were rated "acceptable for documentation"., Conclusion: Image quality of paper prints does not reach the quality of laser films concerning its contrast, grey levels, and spatial resolution. Nevertheless, paper prints are acceptable for documentation of findings in most CT investigations. A high confidence in correct evaluation was found. Limitations are found in documentation of small coin lesions of the lung and ischemic lesions of the neurocranium.

Purpose: The objective of this study was to compare the diagnostic value of cinematic magnetic resonance imaging with static MRI examinations in patients with rheumatoid arthritis and concomitant attack of the cervical spine., Methods: Dynamic functional MRI examinations of the cervical spine were performed one five subjects without complaints and 20 patients with rheumatoid arthritis. For the functional studies, a positioning frame was used that allowed infinitely variable forward and backward inclinations of the head., Results: Functional magnetic resonance imaging made possible a sufficiently good differentiation of the extension of pannus tissue cranial, ventral, and dorsal of the dens with possible displacing and impinging effects on the spinal cord during flexing and stretching movements. In addition, it is suitable for demonstration of the degree of instability in the atlanto-occipital and atlanto-axial planes. In contrast to conventional X-rays, CT, and static MRI, basilary impression as well as compressions and angulations of the cervical bone marrow are better visualized by cinematic magnetic resonance tomography., Conclusions: Functional magnetic resonance tomography is an important diagnostic method for the induction of the cervical spine in patients with rheumatoid arthritis. In particular, fusion and instabilities as well as compressions of the bone marrow often can only be detected with the help of functional MRI.

In spite of all the scientific advances of the past few years, proton magnetic resonance spectroscopy of the brain has not attained the status of a routine examination technique with clinically accepted indications. The method should be considered as an additional option to MR imaging for inherited and acquired encephalopathic changes as well as, in future, for localization diagnosis of epilepsies. A proton magnetic resonance spectroscopic investigation without a prior intensive clinical and imaging investigation is not useful. Above all, factors influencing metabolite distribution such as for example, serum osmolality must be known. Methodological prerequisites for the clinical application of proton resonance spectroscopy are, first of all, a high stability of the chosen technique as well as a sufficiently certain quantification of metabolites and the availability of a reference group. The use of short echo times is necessary for the quantification of glutamine and the osmolyte myo-inositol. Indications for individual cases in which clinical investigations and MR topography cannot provide sufficient certainty and spectroscopy can furnish additional information are, in addition to uses in neuropediatrics, the suspicion of Alzheimer's dementia, HIV encephalopathy in early manifestations, and unclarified depressions of consciousness accompanying liver cirrhosis.

Purpose: To examine if RARE urography may replace conventional intravenous urography in patients with suspected urinary obstruction in pelvic tumours., Materials and Methods: In a prospective trial on 120 patients with pelvic tumours scheduled for operation, biplanar RARE urography was performed and compared to conventional intravenous urography and ultrasound findings., Results: In 30 out of 120 patients an ureteric obstruction was diagnosed by ultrasound. Sensitivity of RARE urography for obstruction was 98% as compared to 60% in conventional intravenous urography. In 12 patients additional retrograde cystoureterography showed a sensitivity of 83%. Specificity of RARE urography and intravenous urography was 100%. In combination with axial MR tomography RARE urography yielded a more precise localisation of the site of obstruction and the underlying cause (98%) as compared to conventional urography (60%) and ultrasound (56%)., Conclusion: By use of RARE urography urinary obstruction can be reliably demonstrated or ruled out. Combining RARE urography with tomographic MR imaging allows the precise depiction of the site of the obstruction and may demonstrate the underlying pathology.

Purpose: In an experimental study, the correlation between the trabecular bone density of the different regions of the proximal femur and the fracture load in the setting of femoral neck fractures was examined., Methods: The bone mineral density of 41 random proximal human femora was estimated by single-energy quantitative CT (SE-QCT). The trabecular bone density was measured at the greatest possible extracortical volume at midcapital, midneck and intertrochanteric level and in the 1 cm3 volumes of the centres of these regions in a standardised 10 mm thick slice in the middle of the femoral neck axis (in mg/ml Ca-hydroxyl apatite). The proximal femora were then isolated and mounted on a compression/bending device under two-legged stand conditions and loaded up to the point when a femoral neck fracture occurred., Results: Statistical analysis revealed a linear correlation between the trabecular bone density and the fracture load for the greater regions, with the highest value in the maximal area of the head (coefficient factor r = 0.76)., Conclusion: According to our data, the measurement of the trabecular bone by SE-QCT at the femoral head is a more confident adjunct than the neck or trochanteric area to predict a femoral neck fracture.

Purpose: With a series of 31 transluminal stent-graft procedures, we assessed the feasibility and clinical effectiveness of a new stent-graft for the treatment of infrarenal abdominal aortic aneurysms (AAAs)., Methods: We treated the patients (male; mean age 71 years) with straight or bifurcated nitinol stents covered with woven dacron graft material for infrarenal eccentric saccular AAA (n = 4) or AAA involving the bifurcation and the common iliac arteries (n = 27). The 18-F delivery system was advanced via a surgical arteriotomy and the stent-graft was placed under fluoroscopic control. Follow-up period ranged from 8 days to 9 months., Results: The implantation of the stent-grafts was technically successful in 30/31 cases. Procedure-related complications were acute hepatic failure due to gastric bleeding in a patient with liver cirrhosis, graft occlusion due to emboli originating from the left atrium (n = 1), macro-embolisation (n = 3), local haematoma (n = 1) and av-fistula (n = 1) requiring surgery. A post-implantation syndrome with leukocytosis and elevated C-reactive protein was observed in all patients., Conclusions: Endoluminal repair of infrarenal AAA with use of dacron covered nitinol stent-grafts is feasible, safe and clinically effective. However, careful long-term evaluation is necessary.

Purpose: A new MRI method for the measurement of femoral torsion and tibial torsion is presented., Methods: Axial images were generated using a standard gradient echo sequence (FLASH 2D). Otherwise measurement of femoral and tibial torsion was performed according to an established CT method., Results: The torsion angles measured using MRI were in accordance with the angles measured using the CT method. The MRI method was not more time-consuming than the CT method., Conclusion: In respect of radiation exposure, MRI determination of femoral and tibial torsion should be considered particularly in children and patients who have to undergo repeated torsion measurements.

In a prospective study we examined the diagnostic ranking of CT and MR in 52 immunocompromised patients with nodular pulmonary lesions and clinical suspicion of invasive pulmonary aspergillosis (IPA). For early diagnosis of IPA (clinical symptoms having existed for less than 10 days) the CT halo sign proved highly sensitive and specific. MRT showed at this time a comparatively high sensitivity but only low specificity that could not be improved upon after Gd-DTPA. At a later stage of the aspergillosis infection (clinical symptoms manifested for more than 10 days) MR identified aspergillus-specific lesions with on-target characteristics (marked enhancement of margins after Gd-DTPA) or the so-called "reverse" target phenomenon (T2-weighted sequences). Such lesions were never seen in the early stage of the disease in patients with nodular pulmonary lesions of different aetiology (pseudomonal or staphylococcal pneumonia).

Following oral administration of a buffered gadopentetate-dimeglumine solution (Magnevist enteral, 1 mmol/l, 6-17 ml/kg) T1-, proton-density- and T2-weighted spin-echo images of abdominal and retroperitoneal lesions were acquired (0.5 T). Gadopentetate is a signal-enhancing, positive MR contrast agent, intraluminal air served as a model of a signal-free, negative agent. In 21 patients contrast/noise ratios of gadopentetate and air versus lesions and fat were compared quantitatively (t-test). In T1- and T2-weighted images contrast/noise ratios of gadopentetate versus lesions were significantly higher than those of air. In proton-density images there was no significant difference. In T1- and proton-density images contrast/noise ratios of air versus abdominal fat were significantly higher than those of gadopentetate, in T2-weighted images gadopentetate had a significantly higher contrast/noise ratio than air. Signal-enhancing positive contrast agents seem advantageous over signal-free negative enteral MR contrast agents.

The possibility of examining brain activity by means of localised spectroscopy was studied in relation to its neurological basis. Measurements on 18 normals during optical stimulation showed an improvement in signal to noise ratio compared with functional imaging of almost one order of magnitude. Time dependent measurements during stimulation by a 500 ms light impulse showed definite delay of increased blood flow when compared with oxygen utilisation. The excellent signal to noise ratio and the inherent stability of the method permits reliable detection of weak effects such as are caused by finger tapping or electrical stimulation.

The capabilities of a patient-oriented digital optical laser-card for the documentation of the image/report unit and for image transmission were assessed. 150 conventional X-rays covering the fields of urology (n = 50), traumatology (n = 50) and orthopaedics (n = 50) were digitised using a CCD scanner and subsequently transmitted to an Image-Transfer Medium (ITM) and to an optical laser-card. The image quality for the detection of relevant diagnostic parameters was evaluated by 4 radiologists and one clinician of the corresponding specialty. Based upon a total of 4740 decision readings for each method, it was found that the optical laser-card reduced the image quality significantly (p < 0.01) in comparison to the digitised ITM images in all fields. Thus, a primary diagnostic statement cannot be made based upon the images of the optical card. However, concomitant documentation of the image and opinion on the card may be used for the transmission of the radiological report, especially to external referring institutions.

Conventional radiographs, axial CT with multiplanar 2-D and 3-D-CT reformations were obtained in 20 patients presenting with craniofacial injuries, to evaluate the capabilities of 3-D-CT. The image quality was assessed by two readers. Sagittal and oblique components as well as comminuted fractures could be detected by 3-D-CT reconstructions similarly to axial CT with 2-D reformations. Displacements over 2 mm were confidently documented by 3-D-CT images. 3-D-CT reconstructions allow an improved demonstration of rotational components of fractured fragments. 3-D-CT images are not as accurate as 2-D-CT in the primary detection of fractures in the relevant anatomic regions. Among 3-D-CT reconstructions, the lateral and partly the facial regions are adequately visualised.

The absorption of the elements iodine, gadolinium and ytterbium in various dilutions was studied in relation to CT. Regression analysis and specific CT density measurements showed that absorption decreases from gadolinium to ytterbium and iodine. These results were confirmed by experiments using ten dogs. Boli of 0.5 molar gadolinium used for angio-CT without table movement showed the largest increase in density in the aorta and liver with an average of 190HU and 21HU respectively compared with iodine which gave 157HU and 12HU respectively. The animal experimental studies suggest that gadolinium and ytterbium are suitable contrast media for dynamic CT investigations.

Radioimmunoscintigraphy (= RIS, scintigraphic "specific" imaging of benign and malignant diseases by means of radioactively marked monoclonal antibodies) has been performed in Germany in clinical studies since 1985 in patients suffering from colorectal cancer. After having been successfully proven in primary studies, RIS is now being used in the early diagnosis of recurrences and metastases. In the prospective study presented here the clinical usefulness of RIS was assessed in comparison against well-tried diagnostic methods including computed tomography in patients suffering from colorectal cancer. It was shown that RIS in SPECT technique (= single photon emission computed tomography) with 99mTc-labelled monoclonal CEA antibodies can visualise local recurrences if diagnostic findings are doubtful, with a sensitivity of 78% versus 50% for CT findings.

In 50 patients with pulmonary disease of varying aetiology and involvement of the pulmonary interstitium, high resolution CT with 1 mm sections have been performed. Various morphological changes within the secondary lobule could be demonstrated which helped in reducing the differential diagnosis. Compared with conventional CT with 10 mm cuts it was also possible to improve the demonstration of pleural lesions by changing window levels.

The study demonstrates the value of angiography and radiological interventions before and after liver transplantation. From September 1988 till February 1991 84% out of 124 hepatic transplant recipients underwent pretransplant angiography evaluation for the exact demonstration of arterial and portal venous blood supply of the liver. Posttransplant angiography was performed in cases with suspected vascular complications, chronic rejection, and spleno-hepatic steal syndrome. Radiological interventions were performed for bacteriological examination and percutaneous drainage of encapsulated fluid collections.

Palpation and CT are used before treatment, in addition to sonography, in patients with tumours in the head and neck for lymph node staging. The accuracy of CT in identifying lymph node metastases is 79% and in our clinical material is similar to the accuracy of palpation (81%). Sensitivity of CT (93%) is better than palpation (82%). Specificity of CT (65%) is less than that of palpation (82%). The high percentage of false positives from CT (35%) is due to enlargement of the lymph nodes resulting from sinus histiocytosis or follicular hyperplasia. CT is significantly superior to palpation in demonstrating the relationship of the lymph nodes to the surrounding tissues (vessels, muscles, bones).

Differentiation between liver metastases and local fat deposition may be difficult when using CT; the value of MRI was therefore investigated in 18 patients with metastases and ten patients with fat deposits. CT shows both lesions as similar hypodense areas. MRI, however, produces different appearances: T1- and 2-weighted images show marked differences in the signal arising from metastases, whereas local fat collections in both sequences differ little in their signal from normal liver. Quantitative MRI signal intensity of the two types of lesion were also different. Where the differentiation by CT may be difficult, it may be made with certainty by means of MRI.

The prospective study includes 25 patients without pathology of the femoral head for the evaluation of the normal femoral head perfusion. In addition 34 patients with femoral head necrosis underwent i.a. DSA preoperatively before pedicled pelvic bone grafting. 15 patients after pelvic bone graft operation and 7 patients with medial femoral head fracture were also examined via superselective DSA. In cases with femoral head necrosis a rarefaction or interruption of the rami nutricii proximales, or an occlusion of the medial circumflex femoral artery were observed. Patients with medial femoral neck fracture showed an interruption of the rami nutricii proximales of the femoral head. Postoperative DSA--after pedicled pelvic bone graft--revealed a regular arterial graft perfusion in 82%.

During a period of nine months, fifteen patients with extensive hepato-cellular carcinomas were subjected to palliative arterial chemo-embolisation using doxorubicin and cisplatin in an emulsion with Lipiodol and/or Spherex particles. Two patients (stage Child C) died within two weeks as the result of liver failure. The remaining thirteen patients showed improvement in their general condition. Subsequent CT showed evidence of tumour reduction and reduction of ascites. Gas production in the tumour was considered as evidence of tumour necrosis. Biochemical results confirmed these findings with a fall of AFP as tumour marker indicating tumour regression.

52 patients with normal pancreas, pancreatitis and pancreatic tumors were examined by magnetic resonance imaging (Magnetom 0.5 T). Using T1-, proton density- and T2-weighted spin-echo sequences images were obtained before and after oral administration of Gadolinium-DTPA (Gd-DTPA, 1 mM, 15 g/l Mannit, 5-13 ml/kg). Gd-DTPA resulted in hyperintense labeling of small bowel in all sequences and improved visualization of pancreatic head, body and tail in 15, 14 and 7 of 27 patients with normal pancreas and in 17, 8 and 6 of 25 patients with diseased pancreas. Better delineation of pseudocysts and tumorous gut wall invasion were diagnostically profitable. With regard to motion artifact reduced MRI of the intestine using fast sequences Gd-DTPA may be a suitable oral contrast agent to improve the imaging of the pancreas.

This is a prospective study of the value of dynamic CT with a rapid scan frequency for the control of liver transplants. In 28 patients dynamic CT was performed with table movement and angio-CT without table movement, using a standard contrast bolus. In 97% of cases the central portions of the portal and hepatic veins could be delineated. The peripheral vessels were better demonstrated by angio-CT (79%) than by dynamic studies with table movement (47%). Parenchymal lesions, such as infarcts, and changes round the liver, such as lymphoedema or haematomas, were adequately demonstrated by either method. In addition, angio-CT provided information on abnormalities of perfusion within the transplant.

Fifty patients with various diseases of the petrous bone were examined by HR-CT with a 1024 x 1024 matrix. It is demonstrated that the improved spacial resolution results in a better discrimination of subtle anatomical structures and therefore leads to an expansion of the diagnostic possibilities in diseases of the auditory and vestibular organs. Evaluation of the two-dimensional reconstructed images shows that best quality is obtained with contiguous 1 mm, sections in the primary scans. In most cases these reconstructed images are diagnostically sufficient. In addition they help to reduce patient strain (no problem with patient positioning, no further x-ray exposure, time-saving). Three-dimensional reconstructions from the base of the skull allow a good visualization of complex and extensive osseous destructions of the temporal bone. The disadvantage of this method is on the one hand the lacking representation of soft tissue and the poor spacial resolution (no 3-D imaging of the ossicular chain), and on the other hand the smoothing of contours because of arithmetical filters. Thus tumor expansion and finer osseous erosions may not be distinguishable. Consequently, 2D primary or reconstructed images must continue to be the basis of diagnosis.

In this prospective study the diagnostic merit of radioimmunoscintigraphy (RIS) was compared with computed tomography (CT) and operation in the primary diagnostic procedure and follow-up of women with suspected ovarian cancer. In primary diagnosis, sensitivity, specificity, and diagnostic accuracy was 100%, 60% and 90% for RIS. In follow-up, sensitivity for local recurrence was slightly higher in CT than in RIS. It was possible to detect peritoneal carcinosis in the pelvis and lower abdominal region better with RIS, but in the upper abdominal region, peritoneal carcinosis was detected better with CT. If no differentiation between benign or malignant lesion, is possible with CT, differentiation will in many cases be possible with RIS.

As part of a radiological communication project (RADKOM), two PACS systems of the radiological clinic in the Rudolf Virchow University Clinic in Charlottenburg and Wedding were connected via the BERKOM network of the German post office. Within the radiology departments, all CT and MRT systems were joined through a local network. The first results have shown that the PACS stations are of value for providing uniformity of diagnosis and for radiological conferences. It is evident, however, that the speed of transfer and the architecture within the PACS system would be of crucial importance for their practicability for radiological conferences.

In 25 patients in whom oral surgery was required, we examined what additional information can be obtained via three-dimensional CT compared with conventional transverse CT scans. We showed that D-3 CT facilitated the spatial orientation by complex osseous destructions. Better therapy planning and postoperative control was therefore feasible. However, CT diagnosis continued to be based on transverse scans.

14 patients with orthotopic liver transplantation were prospectively studied with MR imaging. MR imaging demonstrated a perivascular collar surrounding central portal venous branches in 14 patients. The perivascular collar had low signal intensity on T1-weighted and high signal intensity on T2-weighted images. In 10 of the 14 patients, a perivascular collar was also observed around peripheral portal venous branches. The perivascular collar is probably caused by intraoperative interruption of hepatic lymph vessels and resultant impaired lymph drainage. It is a normal postoperative phenomenon in hepatic transplants. MR imaging is particularly useful in the distinction of postoperative hematoma from other intra- and extrahepatic fluid collections and may provide a noninvasive assessment of liver transplant rejection.

In this prospective study 39 patients with malignant liver tumours were examined by rapid CT. CT was performed before contrast, as dynamic CT, with and without table movement and, in some patients, images were obtained four hours after contrast injection. Time/density curves of hepato-cellular carcinomas (nine cases) showed more rapid and more intense enhancement of the tumour than of the liver parenchyma, whereas tumours of biliary origin (ten cases) showed a slower and less marked enhancement than surrounding tissue. In addition, it was possible to differentiate hypovascular metastases (18 cases) and hypervascular lesions by means of the time-density curve. Best diagnostic information was obtained by dynamic bolus CT. This method without table movement is best for differentiating focal lesions, whereas dynamic CT with table movement shows the extent and number of tumour lesions.