Occlusion Type, Number of Recanalization Passages and Dose Program Determine Radiation Dose in Endovascular Stroke Thrombectomy.

PURPOSE: Identification of independent treatment factors associated with high radiation exposure during endovascular mechanical thrombectomy (EMT) in acute ischemic stroke. METHODS: This retrospective analysis included all patients treated by means of EMT during the 2­year period 2017-2018 in a comprehensive stroke center. The EMT were performed by four internal and three external certified neuroradiologists in a clinic overlapping on call system. Radiation exposure as the dependent variable (dose area product DAP, Gy ⋅ cm2) was dichotomized in < 100 Gy ⋅ cm2 and ≥ 100 Gy ⋅ cm2. Independent variables were age (< 75 years vs. ≥ 75 years), time of intervention (during vs. beyond workday), treating neuroradiologist (internal vs. external), occlusion type ("mono" vs. "tandem"), reperfusion success (TICI 0-2A vs. TICI 2B/3), recanalization attempts (≤ 2 vs. > 2) and dose protocol (normal dose in 2017 vs. low dose in 2018). RESULTS: The EMT treatment of 208 patients (111 female, 97 male, mean age 71.6 years) was analyzed. Median DAP was 86.6 Gy ⋅ cm2 and could be reduced from 104.8 Gy ⋅ cm2 (N = 105 in 2017) to 73.3 Gy ⋅ cm2 (N = 103 in 2018) with LD program. Univariable and multivariable binary logistic regression analysis revealed a significantly increased radiation exposure (≥ 100 Gy ⋅ cm2) in tandem occlusion type (P < 0.001), > 2 recanalization attempts (P < 0.001) and normal dose protocol (P = 0.002). CONCLUSION: Low dose programs can significantly reduce the radiation exposure in EMT. High radiation exposure is significantly associated with more than two recanalization attempts and in cases of tandem occlusions.

Feasibility of non-contrast-enhanced four dimensional (4D) MRA in head and neck tumors, comparison with contrast-enhanced 4D MRA.

BACKGROUND: Information of tumor vascular architecture and hemodynamics is important in treating patients with head and neck tumors (HNTs). The purpose of this study is to investigate the feasibility of non-contrast-enhanced four-dimensional magnetic resonance angiography (non-CE 4DMRA) using arterial spin labeling for anatomical and hemodynamic evaluation of vascularity of head and neck tumors. RESULTS: Non-CE 4DMRA images of 15 patients with HNTs were compared with those of contrast-enhanced 4DMRA (CE 4DMRA) by two independent observers. For qualitative evaluation, overall image quality, visualization of arterial branches and main arterial tumor feeders were assessed. For hemodynamic evaluation, signal-intensity-over-time curves within the tumors were compared. The sensitivity of non-CE 4DMRA for the identification of arterial branches and the main arterial tumor feeders was 75 and 20 %, respectively (interobserver agreement, κ = 0.56 and 0.54, respectively), while that of CE 4DMRA was 99 and 95 %, respectively (interobserver agreement, κ = 0.62 and 0.70, respectively). All three arterial/hypervascularized tumors determined on CE 4DMRA showed distinct signal-intensity-over-time curve pattern on non-CE 4DMRA, with distinct peak and wash out phases. Other tumors showed no wash out on non-CE 4DMRA. CONCLUSIONS: Use of non-CE 4DMRA for the anatomical and hemodynamic evaluation of vascularity of head and neck tumors is feasible, although the technique needs to be improved.

Computer-aided nidus segmentation and angiographic characterization of arteriovenous malformations.

PURPOSE: Exact knowledge about the nidus of an arteriovenous malformation (AVM) and the connected vessels is often required for image-based research projects and optimal therapy planning. The aim of this work is to present and evaluate a computer-aided nidus segmentation technique and subsequent angiographic characterization of the connected vessels that can be visualized in 3D. METHODS: The proposed method was developed and evaluated based on 15 datasets of patients with an AVM. Each dataset consists of a high-resolution 3D and a 4D magnetic resonance angiography (MRA) image sequence. After automatic cerebrovascular segmentation from the 3D MRA dataset, a voxel-wise support vector machine classification based on four extracted features is performed to generate a new parameter map. The nidus is represented by positive values in this parameter map and can be extracted using volume growing. Finally, the nidus segmentation is dilated and used for an automatic identification of feeding arteries and draining veins by integrating hemodynamic information from the 4D MRA datasets. RESULTS: A quantitative comparison of the computer-aided AVM nidus segmentation results to manual gold-standard segmentations by two observers revealed a mean Dice coefficient of 0.835, which is comparable to the inter-observer agreement for which a mean Dice coefficient of 0.830 was determined. The angiographic characterization was visually rated feasible for all patients. CONCLUSION: The presented computer-aided method enables a reproducible and fast extraction of the AVM nidus as well as an automatic angiographic characterization of the connected vessels, which can be used to support image-based research projects and therapy planning of AVMs.

Diagnosis of Toxoplasma gondii infection after allogeneic stem cell transplant can be difficult and requires intensive scrutiny.

Infectious complications remain a major problem after allogeneic hematopoietic stem cell transplant (HSCT). Specifically Toxoplasma gondii infection is a life-threatening condition in immunocompromised patients. In order to highlight the difficulties in obtaining an early and definitive diagnosis, we report three cases of toxoplasmosis after HSCT for hematologic malignancies: two cases of T. gondii retinochoroiditis, and one case of encephalitis. All patients had unrelated donors and received antithymocyte globulin; none had received trimethoprim/sulfamethoxazole prophylaxis. Toxoplasmosis occurred early post-transplant and diagnosis was obtained by real-time PCR. In one case, the correct diagnosis could only be established by PCR analysis of a retinal biopsy specimen. Rapid diagnosis--by invasive approaches--and an immediate onset of antiparasite treatment are crucial to avoid disseminated and often lethal Toxoplasma infections in the post-transplant period. Post-transplant prevention strategies and treatment to control advanced infection in this setting are discussed.

Overexpression of lysosomal acid lipase and other proteins in atherosclerosis.

Atherosclerosis is one of the major causes of morbidity and mortality in the western world. The existing data of elevated expression levels of proteins like DNA damage and DNA repair enzymes in human atherosclerotic plaques are reviewed. From the literature, the effect of overexpression of different proteins using adenoviral vectors or the model of transgenic mice on the development of atherosclerosis will be discussed. Special focus is placed on the lysosomal acid lipase (LAL), because LAL connects extra-cellular with intra-cellular lipid metabolism and is the only hydrolase for cleavage of cholesteryl esters delivered to the lysosomes. Patients with a deficiency of LAL show an accumulation of lipids in the cells and develop pre-mature atherosclerosis. To answer the question of the influence of LAL in atherosclerosis if overexpressed, we show for the first time data of transgenic mice overexpressing LAL and the effect on the lipid level.