Bildgebende Diagnostik bei Chordomen des Beckens: Vergleich der Modalitäten CT und MRT

ZusammenfassungFragestellung Das sakrale Chordom ist ein primär gutartiger Tumor des Knochenskeletts. Eine korrekte und ausreichende Tumorvolumendefinition zur Therapieplanung ist ein entscheidender Prognoseparameter aufgrund der hohen Rate an Rezidiven. Wir untersuchten die Wertigkeit der CT und MRT in der Diagnostik des sakralen Chordoms.Methodik Mittels CT und MRT wurden bei 31 Patienten mit histologisch gesichertem sakralem Chordom Septierung, Ossifikation, Zeichen einer Einblutung, die Kontrastmittelaufnahme des Tumors, die maximale axiale Tumorausdehnung, Weichteilinfiltration, Infiltration des Duralsackes, der Cauda equina und eine Multifokalität durch 2 unabhängige Radiologen untersucht und bewertet.Ergebnisse Alle Chordome zeigten in der CT nativ ein hypodenses und in der MRT ein T2w-hyperintenses Verhalten mit nur mäßiger Kontrastmittelaufnahme. Unter Zugrundelegung des besseren Weichteilkontrastes der MRT gegenüber der CT erwies sich die MRT mit Ausnahme bei Fragen der tumoralen Ossifikation in allen untersuchten Parametern der CT überlegen (p <0,05). Unter alleiniger Anwendung der CT wurde das Tumorvolumen tendenziell unterschätzt.Schlussfolgerung Die MRT sollte bei der Primär- und Rezidivdiagnostik des sakralen Chordoms ein wichtiger Bestandteil der Diagnostik sein.*Die vorliegende Studie wurde im Rahmen des Tumorzentrums Heidelberg-Mannheim durchgeführt.     

Die chronische kritische Unterschenkelischämie: prätherapeutische Diagnostik, Methoden der Revaskularisation

Each year 1-2% of patients with peripheral arterial occlusive disease (pAOD) develop critical limb ischemia (CLI), characterized by rest pain and peripheral ulcer or gangrene. This aggravation of the disease is accompanied by an increase of the 1-year mortality rate up to 25% and a similarly increased frequency of major amputation. We can choose between conservative, endovascular, and surgical procedures for an adequate therapy of the underlying vascular stenoses or occlusions. Yet, clear therapeutic recommendations only exist for suprapopliteal lesions. However, in a number of cases, especially in diabetics, target lesions have an infrapopliteal location. Since endovascular procedures have undergone significant improvement in the last few years, the following review discusses methods for infrapopliteal revascularization taking into consideration the newest publications on this topic.     

Rationale minimal-invasive Therapie der pAVK: wann konservativ, wann PTA, wann Stent?

In order to obtain optimal results and satisfied patients, rational therapy of pAOD should strictly follow national and international society guidelines. In particular cases an individual therapeutic concept seems justified beyond these guidelines. Based on clinical data and driven by costs, aortic and iliac lesions may be treated by PTA or selective stent placement with equal results; however, long-term data justify also primary, direct stenting. For treatment of infrainguinal and popliteal stenotic lesions primary stenting should be restricted to PTA failure (dissection, recoil, occlusion); except for treatment of extended lesions, primary stenting compared to PTA alone seems beneficial in terms of midterm patency. Endovascular procedures below the knee and at the toe should be limited to existing limb-threatening ischemia in order to save the extremity; whether PTA or stenting is advantageous has not yet determined.     

CT-Diagnostik bei akuter zerebraler Ischämie

Zusammenfassung Obwohl die Magnetresonanztomographie (MRT) gegenüber der Computertomographie (CT) Vorteile bei der Frühdiagnostik der akuten zerebralen Ischämie bietet, wird der überwiegende Anteil von Patienten mit frischen Schlaganfällen in Kliniken eingeliefert, denen nur ein CT zur Verfügung steht. In dieser Übersichtsarbeit wird die diagnostische Wertigkeit des Schlaganfall-CT-Protokolls, bestehend aus Nativ-CT, Perfusions-CT und CT-Angiographie (CTA) anhand mehrerer Beispiele diskutiert. Mit der Perfusions-CT kann der Diagnostiker therapierelevante Informationen über die zerebralen Perfusionsverhältnisse (zerebraler Blutfluss, zerebrales Blutvolumen und Transitzeit des Blutes) erhalten. Die CTA liefert wertvolle Informationen über den Gefäßstatus; die Analyse der CTA-Quellbilder bietet zusätzliche Informationen über die Größe des Infarktkerns. Diese Untersuchungstechniken führen nur zu einer minimalen Verzögerung in der Therapie, können dafür jedoch entscheidende Hilfe bei der Patientenselektion für eine Thrombolysetherapie sein.     

Nichtokklusive Ischämie (NOI) des rechtsseitigen Kolons

BACKGROUND: Nonocclusive disease (NOD) is known to be a common cause of ischemic colitis, which is frequently underestimated. MATERIAL AND METHODS: A computer-assisted search of radiological reports at our institute over a period of 18 months, describing ischemic colitis of the ascending colon with an unimpaired perfusion of the superior mesenteric artery, was performed. RESULTS: A retrospective analysis of the clinical and radiological data of 14 patients was performed. In ten cases colonic ischemia was confirmed clinically or intraoperatively. Most of our patients needed intravenous catecholamines due to severe hypotension. However, no significant radiographic predictors could be identified. CONCLUSION: Awareness of NOD seems to be crucial. Especially in cases of acute abdominal pain associated with severe hypotension, renal insufficiency, or pancreatitis, one should include NOD as a differential diagnosis at an early stage.     

CT und MRT der Hüftprothese

Metal-induced artifacts impair image quality of computed tomography (CT) and magnetic resonance imaging (MRI) in patients with hip prostheses. Due to new developments in metal artifact reduction both methods can now be used for evaluation of a painful hip prosthesis. Iterative reconstruction algorithms and dual-energy scans are among the newer CT techniques for artifact reduction, while slice-encoding for metal artifact correction (SEMAC) and multi-acquisition variable-resonance image combination (MAVRIC) have introduced substantial improvements for MRI. Loosening of the hip prosthesis, osteolysis from small wear particles and pseudotumors in metal-on-metal prostheses are specific pathologies in patients with total hip arthroplasty. Other causes of painful hip prostheses are infections, fractures, tendinopathies, tendon ruptures, muscle and nerve alterations and heterotopic ossifications.     

Biopsien von Nierenläsionen: wann und wie?

The demand for image-guided renal biopsy has increased due to the better detection of renal lesions; however, despite modern imaging techniques many small renal tumors cannot be classified as benign because they cannot be differentiated from renal cell carcinoma. Ultrasound and computed tomography (CT)-guided kidney biopsy is a safe and accurate method in the diagnostics of renal lesions and can be helpful in the selection of new ablative and pharmaceutical forms of treatment and avoid unnecessary operations. This article describes the clinical indications for an image-guided biopsy and discusses factors which should be considered when performing a biopsy.     

Echoplanare diffusionsgewichtete MRT in der Diagnostik des akuten ischämischen Schlaganfalls Möglichkeiten und Grenzen bei der Interpretation auffälliger Bildbefunde

Zusammenfassung In den ersten Stunden nach zerebraler Isch?mie ist eine exakte Diagnosestellung h?ufig schwierig. Die diffusionsgewichtete (DW) Magnetresonanztomographie (MRT) erm?glicht die bildliche Darstellung betroffener Parenchymanteile und quantitative Erfassung der Gewebever?nderungen, noch bevor eindeutige Auff?lligkeiten im T₂-gewichteten Bild nachweisbar sind. Wir analysierten 105 MRT-Untersuchungen akuter Schlaganf?lle (<24 h) in Hinblick auf typische Befundkonstellationen in der T₂- und DW MRT. Weiterhin wurde der Einflu? der bei DW echoplanarer (EP) Einzelpuls („single shot”) Me?techniken h?ufig auftretenden Bildartefakte auf die Bildbefundung ausgewertet. In Abh?ngigkeit vom Untersuchungszeitpunkt zeigten sich drei z.T. zeitlich überlappende T₂/DW Konstellationen: a) In der sehr frühen Infarktphase (≤1,5 Stunden) fehlende T₂-Auff?lligkeiten, bei gleichzeitig ebenfalls noch nicht nachweisbarer Diffusionsst?rung; b) fehlende T₂-Ver?nderung bei gleichzeitigen Zeichen einer reduzierten Diffusion (1,5–4 h); c) eindeutige T₂-Hyperintensit?t bei gleichzeitig eingeschr?nkter Diffusion (≥3 h). Es fanden sich typische Artefakte in Form von Suszeptibilit?tsverzerrungen, N/2 Artefakten, Fettsignal-(„chemical shift”)Artefakten und Wirbelstromverzerrungen, die bei der Befundinterpretation berücksichtigt werden müssen. Die Kenntnis der typischen Bildartefakte vorausgesetzt, erm?glicht EP DW-Bildgebung eine exaktere Diagnose akuter Schlaganf?lle.      

CT und MRT bei intrinsischen raumfordernden Läsionen der knöchernen Schädelbasis

Intrinsic bony lesions of the skull base are diseases which arise within the bones forming the skull base. Mainly they are bone tumours and tumour-like lesions. With the exception of osteomas of the paranasal sinuses and exostoses of the external auditory canal, these lesions occur rarely. This article gives an overview of the appearance of the most common primary bony skull base masses in CT and MRI. From the authors’ point of view these are fibrous dysplasia, chordomas, chondrosarcomas, Langerhans cell histiocytosis and multiple myelomas, which must be differentiated from pseudolesions. The possibilities of CT and MRI in making a specific diagnosis, differential diagnosis and the kind of making the final diagnosis are described.     

Untersuchung der atemabhängigen Bewegungen pulmonaler Raumforderungen mit der MRT

Parallel imaging and echo sharing techniques have markedly reduced the acquisition times for MRI of large volumes. Dynamic 2 and 3-dimensional data sets of the chest with high temporal resolution (up to 10 images/s with single slice and 2 volume/s) allow an analysis of respiratory motion of the lungs and tumors. Time-resolved 2D series in preselected planes can be used to observe respiratory motion during free breathing or after respiratory commands, e.g. to exclude chest wall invasion by a tumor or for diagnosing impairment of respiratory mechanics. Time-resolved 3D-series (4D-MRI) allow monitoring of the spatial displacement of the lungs and tumors as a whole volume. Present limitations such as an overestimation of tumor size and an underestimation of displacement due to a limited temporal resolution are expected to be overcome with further technical developments. However, 4D-MRI already appears to be the appropriate tool to select patients for motion-adapted radiotherapy. In addition 4D-MRI is available for a broad spectrum of scientific applications, as it allows repeated and prolonged series of measurements without radiation exposure.     

Ganzkörpertumorstaging: MRT oder FDG-PET/CT?

Technical innovations such as the availability of movable patient platforms and the introduction of 32-channel systems have made whole-body MRI for tumor staging feasible. In addition, the development of dual-modality PET/CT systems offers the opportunity to perform anatometabolic tumor staging with whole-body coverage in a single session. Based on an increase in patient survival when applying a stage-adapted therapy in different malignant diseases the relevant question relates to the accuracies of whole-body MRI and whole-body PET/CT for TNM staging. This review article addresses whole-body tumor staging with MRI and FDG-PET/CT with special emphasis on diagnostic accuracies for staging different malignant diseases.     

Prognostischer Wert der kardiovaskulären MRT bei Diabetikern

Die Radiologie - Trotz eines im Durchschnitt erhöhten kardiovaskulären Risikos sind Diabetiker eine heterogene Population mit höchst unterschiedlichen individuellen...     

Ischämie der unteren Extremität durch eine persistierende A. ischiadica – ein möglicher interventioneller Therapieansatz

The sciatic artery is a rarely seen variant of the vessels of the lower limb. Anatomically it is the prolongation of the inferior gluteal artery and accompanies the sciatic nerve from the sciatic foramen to the knee. More than other vessels, the sciatic artery shows vasculopathies like diffuse dilatation or aneurysms. This report describes an interesting case of embolic acute ischemia, caused by a persistent sciatic artery with an aneurysm. We treated the ischemia with intra-a. lysis and bridged the aneurysm with an covered stent.     

MR-Bildgebung der Nieren Neue Ansätze in der Diagnostik*

AIM: New diagnostic strategies for evaluation of the kidney by fast MR imaging techniques. MATERIAL AND METHODS: A comprehensive morphologic and functional evaluation of the kidney is proposed using fast MR imaging of renal morphology, multiphase 3D gadolinium MR angiography, MR urography and MR flow measurements. A single MR examination is designed to grade renovascular disease and assess the hemodynamic and functional significance, detect and characterize renal lesions and evaluate the urinary tract. RESULTS: The combined analysis of morphologic and functional data allows reliable assessment of renal artery stenosis, benign and malignant renal masses and diseases of the renal collecting system and ureters, as well as congenital abnormalities in good agreement to the results of conventional imaging modalities. The improved tissue contrast and additional functional information compensates for the disadvantage of a lower spatial resolution. CONCLUSION: Combined morphologic and functional MR examination represents a reliable, non-invasive and cost-effective alternative imaging modality for comprehensive diagnostic evaluation of renal disease.     

Einsatz der Dual-source-Computertomographie in der prä- und postoperativen kardiochirurgischen Diagnostik

PURPOSE: The aim of this study was to evaluate the clinical potential of dual-source computed tomography (DSCT) in pre- and postsurgical diagnostics in the field of cardiac surgery. MATERIAL AND METHODS: A total of 20 patients underwent DSCT of the heart. This CT system with two rotating X-ray tubes (Somatom Definition, Siemens Medical Solutions, Forchheim, Germany) achieves a temporal resolution of 83 ms and a spatial resolution of 0.4 x 0.4 x 0.4 mm. The patient cohort consisted of two subgroups. In a group of ten patients with known coronary artery disease (CAD), scheduled for bypass surgery (i.e., high pretest likelihood for having significant CAD), the results of DSCT coronary angiography (CTA) and invasive quantitative catheter angiography (QCA) were compared to assess the diagnostic accuracy of DSCT in the detection of significant coronary artery stenoses (>50%). In a second group of ten patients with previous aortic valve replacement (homografts), the valve opening area of the transplanted aortic valve graft was measured by DSCT and compared with echocardiography as a standard of reference to exclude postsurgical restenosis of the valve. RESULTS: Of 150 coronary artery segments depicted by CT, 144 (96%) were classified as "assessable." A significant CAD was known in all patients, and altogether 43 significant stenoses were present according to the results of QCA. Blinded to these results, DSCTA reached a sensitivity and specificity of 95% (41/43) and 93% (103/111), yielding a positive and negative predictive value (PPV, NPV) of 79% (31/39) and 98% (103/105), respectively. In patients with aortic valve homografts, all DSCT datasets were considered as being of diagnostic image quality concerning valve depiction. The planimetric evaluation of the CT data as compared to results of echocardiography showed a significant correlation of the results (r=0.64, p=0.0467). A high-grade valve stenosis (opening area <1.0 cm(2)) could be correctly excluded by DSCT in all patients. CONCLUSIONS: Dual-source CT shows great diagnostic potential in patients before or after cardiac surgery. DSCT provides a high diagnostic accuracy for detection of coronary artery stenosis before bypass surgery. DSCT also proved to be accurate in the assessment of patients who received aortic valve replacement.