Aktuelle und effektive bildgebende Diagnostik von Sprunggelenk und Fuß

Projection radiographic techniques have been used in a standardized manner for decades for the diagnosis of conditions of the foot and ankle; the indications for them and the pattern of findings useful in the initial diagnosis and monitoring of the course are generally known to clinical radiology staff. Computed tomography has been introduced as an extension of the basic procedures performed for diagnosis in the ankle and the hindfoot. In the case of complex fractures, however, specialist experience is essential. CT is an easily accessible investigative procedure and is meanwhile economical and very powerful. Magnetic resonance imaging supplements the range of investigations in special cases when there are particular problems. Microfractures, findings indicative of inflammation and/or dystrophy and, in particular questions concerning the musculoligamentous support system are the situations in which such investigations are needed. Ultrasound has an additive value vis-à-vis magnetic resonance imaging and is an easily accessible and highly effective examination procedure both for the primary diagnosis and for serial monitoring. Financial constraints in the healthcare sector are increasingly limiting purely medical indications. Regardless of this development, the retention of projection radiography, computer tomography, and magnetic resonance imaging must be demanded for the initial diagnosis in the care of foot and ankle injuries. The earliest possible implementation of all these techniques for the initial diagnosis is the first step towards effective treatment. Cafrefully chosen and, if appropriate, complementary strategies are needed for monitoring of the course and for assessment.     

CT and MRI of the petrous bone

Diseases of the petrous bone should now be diagnosed by means of high-resolution multislice spiral computed tomography (MSCT) and/or magnetic resonance imaging (MRI). The first step in the process of diagnosis, however, must be conventional X-ray photographs (according to Schüller, Mayer, Stenvers) for screening purposes, because of the high cost of the other procedures mentioned. Because of the excellent imaging of bone structures with MSCT, this technique is especially suitable for the diagnosis both of acquired pathologies and of congenital abnormalities of the external auditory meatus, the middle ear and the mastoid, of trauma-induced pathologies of the entire petrous bone, and of osteogenic diseases. MRI is the method of choice for examination of the labyrinthine system, the interior auditory meatus and the cerebellopontine angle because it gives much the best depiction of soft tissue. Sometimes when questions remain unsolved after computed tomography (CT) examination of the middle ear MRI can be applied to complement CT, and it can yield additional information. Lesions affecting the apex of the petrous pyramid should be examined by MRI. High-resolution CT through the bone window and thin-layer MRI are both components of the presurgical diagnosis before cochlear implant (CI) surgery. For postoperative monitoring a conventional transorbital X-ray of the petrous bone is sufficient; CT is indicated only in complicated cases, and MRI is absolutely contraindicated after CI.     

New abdominal CT angiography protocol on a 16 detector-row CT scanner - first results

Purpose. Purpose of this study was the implementation of a new abdominal CT angiography protocol on a 16 detector-row CT scanner and the comparison to selective catheter angiography. Methods. 76 patients with various vascular disorders underwent abdominal CT angiography on a recently developed 16 detector-row CT scanner using submillimeter slice collimation (16×0.75 mm). Results were compared with mesenteric and/or hepatic angiography in 17 patients performed during tumor embolization. Opacification was provided using individually tailored contrast application with a test bolus setting. To evaluate the contrast injection protocol density measurements within the vessel lumen were performed. Results. Diagnostic image quality was achieved in all patients with angiographic comparison (n = 17). Within the hepatic and mesenteric vasculature up to 4th generation vessels could be identified. Compared to selctive angiography CT angiography provided equivalent morphologic information up to the detectable vessel generation. With the applied contrast application regimen there were no significant differences in vessel enhancement along the abdominal aorta and iliac arteries. Conclusion. 16 detector-row CT enables whole abdominal angiographic studies with submillimeter resolution in a single breath-hold. The improved spatial resolution enables for high quality 3D visualization. Compared to invasive angiography, 16 detector-row CT reveals equivalent morphologic information.     

Radiologische Diagnostik der Leber

Highly specific methods are required for the diagnostic workup of focal hepatic lesions, since benign circumscribed liver changes are very common. Although cross-sectional imaging techniques have a high diagnostic accuracy, radionuclide imaging techniques such as colloid, red blood cell, or hepatobiliary scan are commonly performed when a benign lesion is assumed since these permit a definite diagnosis with high specificity. The diagnosis of a primary or secondary malignant liver tumor, however, usually relies on radiological imaging techniques alone, supported by needle biopsy. Whether positron emission tomography as a primary or supplementary diagnostic tool will have a role in the routine staging of malignant tumors remains to be determined.     

Technik und Strahlendosis konventioneller Röntgenaufnahmen und Computertomographie des Sakroiliakalgelenks

Zusammenfassung Röntgenaufnahmen des Sakroiliakalgelenks im anterior-posterioren bzw. posterior-anterioren Strahlengang, gelegentlich ergänzt durch die Schrägaufnahme, sind seit vielen Jahren die Methode der Wahl für die Diagnostik bei Patienten mit Verdacht auf Sakroiliitis. Die Sensitivität und Spezifität des konventionellen Röntgens sind relativ niedrig, was die Diagnose der Sakroiliitis verzögern könnte. Die Computertomographie (CT) ist dem konventionellen Röntgen für die Diagnostik der Sakroiliitis überlegen, verursacht jedoch eine relativ hohe Strahlendosis. Aus diesem Grund sollte besonders bei Frauen die CT durch die Verwendung semikoronarer Scanebenen optimiert werden, die mit einer niedrigeren Strahlendosis als bei den axialen Scanebenen auskommen. Eine semikoronare Schnittführung in der CT ruft eine minimale Strahlenbelastung der Ovarien hervor, und die effektive Strahlendosis bei Frauen dürfte deswegen sogar noch niedriger als bei konventionellen AP Röntgenaufnahmen sein. Folglich wird die semikoronare Schnittführung in der CT, bei Verdacht auf Sakroiliitis, diagnostisch und hinsichtlich des Strahlenschutzes bei jungen Frauen als bildgebendes Verfahren bevorzugt, wenn keine Magnetresonanztomographie (MRT) zur Verfügung steht. Bei Männern können die Gonaden bei konventionellen Röntgenaufnahmen vor der Strahlendosis geschützt werden, die CT kann hier lediglich aufgrund des überlegenen diagnostischen Wertes als erstes bildgebendes Verfahren gerechtfertigt werden. Die MRT ist aufgrund der fehlenden Risikofaktoren diagnostisch der CT überlegen, da zusätzlich zur Gelenkdestruktion auch Entzündungszeichen dargestellt werden können. Daher ist bei entsprechender Verfügbarkeit die MRT für die Diagnostik der Sakroiliitis zu bevorzugen.     

Heutiger Stand und zukünftige Entwicklungen in der Mehrschichtcomputertomographie

Zusammenfassung In diesem Übersichtsartikel werden der heutige Stand und das zukünftige Entwicklungspotenzial der Mehrschichtcomputertomographie beleuchtet. Wesentliche Vorteile der etablierten 4- bis 16-Schicht-CT-Geräte liegen in größerer Volumenabdeckung, besserer Nutzung der Röntgenröhre und v. a. verbesserter transversaler Auflösung. Spiraluntersuchungen mit 16 Submillimeterschichten stellen einen Durchbruch auf dem Weg zu räumlich isotroper Bildgebung für alle Routineanwendungen dar. EKG-gesteuerte CT-Untersuchungen des Herzens profitieren von der verbesserten zeitlichen und räumlichen Auflösung der neuen Generation der 16-Schicht-CT-Geräte. Im Vergleich zu 4-Schicht-Scannern sind Kardiountersuchungen klinisch wesentlich robuster. Das größte Verbesserungspotenzial für die Mehrschicht-CT des Herzens liegt in einer weiteren Steigerung der zeitlichen Auflösung der Bilder, die klinisch robust mit erhöhter Gantryrotationsgeschwindigkeit erreicht werden kann. Kombinierte Systeme wie PET-CT-Scanner werden in naher Zukunft an klinischer Bedeutung gewinnen. Für allgemeinradiologische Anwendungen geht das Wettrennen um höhere Zeilenzahlen weiter, das schließlich in die Einführung von CT-Geräten mit Flächendetektoren münden wird.     

Die postoperative Kontroll-CT nach Acetabulumfraktur

Fractures of the acetabulum are severe injuries of the hip joint. Exact preoperative management is necessary to make possible an anatomical reconstruction. Postoperative quality control is done best with computed tomography. Is the higher radiation exposure caused by this routine examination justified? During the 5 years from 1995 to 1999, a total of 154 patients with fractures of the acetabulum were examined postoperatively at our clinic using CT to control reconstruction, implant position and the remaining free fragments in the joint. Thirteen of these patients (8.4%) had to be re-operated after postoperative CT control. The causes of the re-operation were four cases of an intra-articular implant position, three of free fragments remaining in the joint, and in 6 patients showed inadequate reconstruction. The mean radiation exposure was 25 mGy per patient. The low mean age of the patients and the long lasting consequences of a probably unrecognised complication, justify routine, postoperative CT control, even though the radiation exposure is about 10 mGy higher than the conventional radiological diagnosis. The use of CT diagnosis as a routine postoperative measure is an appropriate control procedure that allows an objective assessment of the quality of the result for the patient as well as for the surgeon.     

Verbesserung der Diagnostik von Lebermetastasen mit der Multi-Detektor-CT

The introduction of multidetector computed tomography in clinical routine creates a new dimension of increased spatial and temporal resolution in CT scanning. On the basis of the very short acquisition time, the whole liver can now be scanned within one breathhold. Multidetector-CT allows the examination of the liver with nearly isotropic data sets. This is the prerequisite for the optimal assessment of very small liver lesions in all planes and excellent enhancement of liver lesions in defined organic perfusion phases. The speed of multidetector-CT can either be used to reduce the time to cover a given volume, or to use narrower beam collimation to increase the resolution of details along the z-axis and to reduce volume averaging. We report our clinical experiences in hepatic multidetector-CT examinations and optimized examination protocols in the assessment of hepatic metastases. Multidetector-CT and the use of interactive multiplanar reconstructions improve the detection and characterization of liver metastases. However, new problems in data management may arise from the large amount of data generated by multidetector-CT.