[Complicated acute type B aortic dissection-what does endovascular therapy contribute?] / Akute komplizierte Typ-B-Dissektion ­ was leistet die endovaskuläre Therapie?

BACKGROUND: Acute aortic dissection type B is a severe and life-threatening vascular emergency. Complications such as rupture and/or malperfusion of organs are the main reasons for early mortality. OBJECTIVES: The aim is to provide an overview on important diagnostic radiological findings, conservative as well as endovascular therapeutic options for patients presenting with rupture or malperfusion syndromes. RESULTS: Medical treatment consisting of blood pressure and heart rate control as well las adequate analgesia remains the cornerstone therapy of all type B aortic dissections. In case of organ malperfusion, various endovascular therapies, e. g., endoluminal fenestration of dissection flap, thoracic stent-graft implantation (TEVAR) or branch vessel stenting, are available. In the case of aortic rupture, TEVAR has become the standard owing to its lower mortality compared to open surgical repair. DISCUSSION: For the treatment of complicated type B aortic dissection, a number of endovascular options are available. For optimal treatment, profound knowledge of the disease, of the diagnostic workup, and of the interventional procedures is mandatory.

Model-based iterative reconstruction for improvement of low-contrast detectability in liver CT at reduced radiation dose: ex-vivo experience.

AIM: To compare low-contrast detectability, and qualitative and quantitative image parameters on standard and reduced radiation dose abdominal CT reconstructed with filtered back projection (FBP) and model-based iterative reconstruction (MBIR). MATERIALS AND METHODS: A custom built liver phantom containing 43 lesions was imaged at 120 kVp and four radiation dose levels (100% = 188 mAs, 50%, 25%, and 10%). Image noise and contrast-to-noise ratios (CNR) were assessed. Lesion detection and qualitative image analysis (five-point Likert scale with 1 = worst, 5 = best for confidence) was performed by three independent radiologists. RESULTS: CNR on MBIR images was significantly higher (mean 246%, range 151-383%) and image noise was significantly lower (69%, 59-78%) than on FBP images at the same radiation dose (both p < 0.05). On MBIR 10% images, CNR (3.3 ± 0.3) was significantly higher and noise (15 ± 1HU) significantly lower than on FBP 100% images (2.5 ± 0.1; 21 ± 1 HU). On 100% images, lesion attenuation was significantly lower with MBIR than with FBP (mean difference -2 HU). Low-contrast detectability and qualitative results were similar with MBIR 50% and FBP 100%. CONCLUSION: Low-contrast detectability with MBIR 50% and FBP 100% were equal. Quantitative parameters on even lower dose MBIR images are superior to 100%-dose FBP images. Some attenuation values differ significantly with MBIR compared with FBP.