Degradable starch microspheres transarterial chemoembolisation (DSM-TACE) of HCC: Dynamic Contrast-Enhanced Ultrasonography (DCE-US) based evaluation of therapeutic efficacy using a novel perfusion software.

PURPOSE: To evaluate therapeutic efficacy of degradable starch microsphere (DSM)-TACE in hepatocellular carcinoma (HCC) using Dynamic Contrast-Enhanced Ultrasonography (DCE-US) based perfusion analysis. MATERIALS AND METHODS: A total of 60 DCE-US examinations were performed in 15 selected patients who underwent DSM-TACE with EmboCept®S for the treatment of advanced HCC. DCE-US was performed via i.v. application of ultrasound contrast media before and 24 hours post embolization. In addition DCE-US was performed with i.a. contrast application via the angiographic catheter right before and after the embolization. Microcirculation of embolized HCC lesions was quantified using a dedicated perfusion software by two experienced radiologists in consensus. RESULTS: Significant reduction of microvascularization (PE, WiAUC and WiR) was seen right after DSM-TACE and during 24 hour follow-up. Mean PE was 342.22 ± 97.80 prior to embolization, 59.28 ± 29.74 post embolization (p = 0.019) and 18.83 ± 7.03 during follow-up (p ≤ 0.01). Mean WiAUC was 1103.21 ± 432.05 prior to embolization 267.69 ± 151.80 post embolization (p = 0.023) and 105.10 ± 44.43 during 24 hour follow-up (p ≤ 0.01). The corresponding values for WiR were 224.91 ± 57.97 prior-, 38.14 ± 18.80 post embolization (p = 0.034) and 6.97 ± 2.68 during follow up (p ≤ 0.01). CONCLUSION: In this study, therapeutic efficacy of DSM-TACE in HCC using DCE-US based perfusion analysis could be demonstrated.

[Superior vena cava occlusion : Radiological placement of a central venous port system via femoral vein access]. / Okklusion der V. cava superior : Radiologische Implantation eines zentralvenösen Portsystems über einen femoralen Zugang.

We report on a young patient with cancer of unknown primary origin with occlusion of the superior vena cava due to mediastinal lymphadenopathy. In order to continue infusion of palliative chemotherapy a central venous port system was radiologically implanted via a right femoral vein access. The port reservoir was placed craniomedial to the right anterior superior iliac spine. This approach was considered convenient in respect to comfort in wearing trousers. In addition, at this site the port reservoir is easily accessible for medical staff. It was possible to draw blood via the port system and to infuse the chemotherapy without complications. The present case shows that in cases of occlusion of the superior vena cava radiological implantation of a central venous port system via a femoral vein access is a useful option.

Evaluation of the microcirculation of hepatocellular carcinomas using contrast-enhanced ultrasound with intraarterial and intravenous contrast application during transarterial chemoembolization with drug-eluting beads (DEB-TACE): preliminary data.

PURPOSE: The objective was the evaluation of microcirculation in hepatocellular carcinomas (HCC) in vivo by dynamic contrast-enhanced ultrasound (CEUS) after intravenous (i.v.) and intraarterial (i.a.) application of contrast agent during transarterial chemoembolization (TACE) using drug-eluting beads (DEB). PATIENTS AND METHODS: Eleven patients with HCC underwent CEUS directly before and immediately after DEB-TACE. The sonographic contrast agent was injected through the microcatheter intraarterially and intravenously. The grade of hypervascularization was evaluated before Bead application. The percentage of devascularization after Bead application was calculated and quantitative devascularization was carried out using time intensity curves (TIC). These results were compared to postinterventional angiography after Bead application and postprocedural computed tomography. RESULTS: The hypervascularization of HCC was marginal improved after i.a. contrast application compared to i.v. application (p = 0.163). The reduction of vascularization after Bead application correlated significant between i.a. and i.v. contrast application (p = 0.007) and decreased significant using TIC analysis (p = 0.003). Postinterventional angiography related with CEUS after i.a. sonographic contrast agent application. Extrahepatic tumor-feeding arteries were detected by a mismatch between i.a. and i.v. CEUS in one case. CONCLUSION: Quantification of the reduction of microvascularization using TIC analysis may be a valuable periinterventional tool during DEB-TACE. Intraprocedural CEUS with i.a. and i.v. ultrasound contrast agent injection may help finding extrahepatic tumor-feeding arteries.

Pre-surgical evaluation of ICA-stenosis using 3D power Doppler, 3D color coded Doppler sonography, 3D B-flow and contrast enhanced B-flow in correlation to CTA/MRA: first clinical results.

AIM: Pre-surgical evaluation of the extent of internal carotid artery stenosis (ICA) according to NASCT criteria using digital 3D ultrasound methods. MATERIAL/METHODS: In a prospective study, 25 patients (54-88 years, mean 75) with neurological deficits and the diagnosis of ICA stenosis underwent pre-surgical ultrasound examination using Color Coded Duplex Sonography (CCDS), 3D CCDS, 3D power Doppler, 3D B-flow, contrast enhanced 3D B-flow, and CTA/MRA. Ultrasound was performed by an experienced examiner with a multifrequency linear transducer (6-9 MHz, Logiq 9, GE). After bolus injection of 2.4 ml Sonovue i.v., low mechanical index technique (MI<0.16) was used for contrast enhanced 3D B-flow. As reference method for evaluation of the extent of ICA stenosis each patient underwent CTA (multislice CT, Sensation 16, Siemens) and/or MRA (1.5 T, Symphony Siemens). Indications for surgery (carotid EEA) followed the NASCET criteria. All images were interpreted and evaluated independently by two observers with three measurements of the degree of the ICA stenosis. For assessment of the extent of stenosis a 10%-scale from 50% to 99% was used. Statistical analysis was performed using Spearman Correlation and Wilcoxon Signed Rank Test with a significance threshold of p<0.05. RESULTS: Assessment of the extent of ICA stenosis during surgery and in CTA/MRA displayed a range from 60% to 99% (mean 80%). Non significant differences were found with paired Wilcoxon test only for 3D B-flow with and without contrast medium (p<0.05). Correlation with surgical evaluation regarding the extent of ICA stenosis using Spearman correlation teat was 0.77 for B-scan, 0.90 for 3D CCDS, 0.84 for 3D Power Doppler, 0.91 for B-flow and 0.93 for contrast enhanced 3D B-flow. When circular calcifications were present, contrast enhanced flow detection of 3D B-flow proved to be useful. Visualisation of intrastenotic variances of severe and profound stenosis (70-99%) without blooming and reverberation artefacts was possible only with 3D B-flow. This facilitates the detection of the morphology of plaques ulcers as an embolic source. CONCLUSION: In correlation with surgery and CTA/MRA, a valid evaluation of the extent and morphology of ICA stenosis using 3D B-flow, with and without contrast medium, is feasible.

Microcirculation and perfusion with contrast enhanced ultrasound (CEUS) in Crohn's disease: first results with linear contrast harmonic imaging (CHI).

AIM: To evaluate a newly introduced high resolution linear transducer for vascularization and mural perfusion assessment using contrast harmonic imaging (CHI) with quantitative time intensity curve analysis (TIC) in patients with active Crohn's disease (CD). MATERIAL AND METHODS: We prospectively evaluated 14 consecutive patients (7 women, 7 males, age range 19-42 years, median 28 years) with histologically proven CD having an acute episode of the disease applying contrast enhanced MRI and high resolution ultrasound. For the ultrasound we used a newly introduced high resolution linear multi-frequency transducer (6-9 MHz, Logiq 9, GE). Ultrasound was performed by an experienced radiologist applying color coded Doppler sonography (CCDS), power Doppler (PD) and contrast enhanced CHI using the 'true agent detection mode'. Additionally, 5 healthy volunteers were examined by ultrasound applying CCDS, PD and CHI. After the injection of 2.4 ml ultrasound contrast agent (SonoVue) the dynamic CHI cine sequences were recorded as digital raw data for 60 seconds. Therefore we were able to perform a quantitative perfusion analysis using TIC retrospectively. CCDS, PD and CHI with TIC were compared and analyzed. RESULTS: In all 14 patients MRI showed inflammatory changes in the terminal or pre-terminal ileum. Using PD and CCDS enlarged vessels surrounding the bowel wall were visualized in all patients. PD as well as CCDS diagnosed just in 9 of 14 patients augmented mural vessels. Having CHI with TIC increased mural contrast enhancement was diagnosed in all 14 patients. Patients with CD showed a maximum enhancement 36 s after injection with 9 dB (range 5.9-13.2 dB), while healthy volunteers reached the maximum level of 2.8 dB (range 2-3.8 dB) after 23 s (p<0.05). CONCLUSION: Using high resolution linear transducer mural perfusion changes in active Crohn's disease can be appreciated applying CHI with TIC. This technique could be an effective dynamic imaging modality for diagnosis and especially follow-up examination to monitor treatment in CD.

Vacancy-impurity complexes in highly Sb-doped Si grown by molecular beam epitaxy.

Positron annihilation measurements, supported by first-principles electron-structure calculations, identify vacancies and vacancy clusters decorated by 1-2 dopant impurities in highly Sb-doped Si. The concentration of vacancy defects increases with Sb doping and contributes significantly to the electrical compensation. Annealings at low temperatures of 400-500 K convert the defects to larger complexes where the open volume is neighbored by 2-3 Sb atoms. This behavior is attributed to the migration of vacancy-Sb pairs and demonstrates at atomic level the metastability of the material grown by epitaxy at low temperature.

Evidence for a new class of defects in highly n-doped Si: donor-pair-vacancy-interstitial complexes.

Electron channeling experiments performed on individually scanned, single columns of atoms show that in highly n-type Si grown at low temperatures the primary electrically deactivating defect cannot belong to either the widely accepted class of donor-vacancy clusters or a recently proposed class of donor pairs. First-principles calculations suggest a new class of defects consisting of two dopant donor atoms near a displaced Si atom, which forms a vacancy-interstitial pair. These complexes are consistent with the present experimental results, the measured open volume of the defects, the observed electrical activity as a function of dopant concentration, and the enhanced diffusion of impurities in the presence of deactivated dopants.

Atomic-scale imaging of individual dopant atoms and clusters in highly n-type bulk Si.

As silicon-based transistors in integrated circuits grow smaller, the concentration of charge carriers generated by the introduction of impurity dopant atoms must steadily increase. Current technology, however, is rapidly approaching the limit at which introducing additional dopant atoms ceases to generate additional charge carriers because the dopants form electrically inactive clusters. Using annular dark-field scanning transmission electron microscopy, we report the direct, atomic-resolution observation of individual antimony (Sb) dopant atoms in crystalline Si, and identify the Sb clusters responsible for the saturation of charge carriers. The size, structure, and distribution of these clusters are determined with a Sb-atom detection efficiency of almost 100%. Although single heavy atoms on surfaces or supporting films have been visualized previously, our technique permits the imaging of individual dopants and clusters as they exist within actual devices.

Surface diffusion and islanding in semiconductor heterostructures.

Molecular beam epitaxy (MBE) is an important technique for the creation of new, non-equilibrium semiconductor materials and structures exhibiting novel physical phenomena. Surface diffusion plays an important role in the growth of these structures, influencing such fundamental growth processes and constants as islanding, critical thickness and epitaxial temperatures. Two approaches to the general problem of surface diffusion and islanding, using the SiGe system as a prototypical semiconductor heterostructure, are discussed: The time evolution of patterned deposits, and kinetic studies of nucleation and growth. While disordered laminar growth occurs for deposition at 300 K, elevated temperatures lead to Stranski-Krastanow (SK) growth (uniform coverage theta SK with excess Ge in islands). Diffusion coefficients for Ge on Si(100) have been determined for coverages below theta SK and show a significant coverage dependence. They are extremely sensitive to contamination with carbon on the order of approximately 0.05 ML, as well as to e-beam irradiation. In situ annealing experiments were performed to study the islanding process in real time. Provided the initial coverage exceeds the thickness of the SK layer, theta SK approximately 3 ML on Si(100)2 x 1, the initially uniform but disordered layer begins to collapse into a SK-type morphology at about 250 degrees C. At a ramping rate of 0.1 degrees C/s this process is completed at approximately 400 degrees C. A temperature dependence of the SK-layer thickness has been discovered for the first time. It is in excellent agreement with theoretical predictions.

[The special case. Thyrogenic acropachy]. / Der besondere Fall. Thyreogene Akropachie.

Thyroid acropachy is a typical, though rare complication, of Graves' disease. It is seen in about 1% patients, often after a course of several years. It may occur while the patient is euthyroid, hyper- or hypothyroid. In most cases it is part of a syndrome including exophthalmos and pretibial myxedema. We describe the course of a patient's disease and discuss the criteria of diagnosis as well as the possible pathogenetic role of antithyroid immunoglobulins in thyroid acropachy.