Novel high-resolution contrast agent ultrasound techniques HiFR CEUS and SR CEUS in combination with shear wave elastography, fat assessment and viscosity of liver parenchymal changes and tumors.

BACKGROUND: The continuous development of ultrasound techniques increasingly enables better description and visualization of unclear lesions. New ultrasound systems must be evaluated with regard to all these diagnostic possibilities. METHODS: A multifrequency C1-7 convex probe (SC7-1M) with the new high-end system Resona A20 Series was used. Modern technologies, including HiFR CEUS, SR CEUS and multimodal tissue imaging with shear wave elastography (SWE), fat evaluation and viscosity measurements (M-Ref) were applied. RESULTS: Of n = 70 (mean value 48,3 years±20,3 years, range 18-84 years) cases examined, a definitive diagnosis could be made in n = 67 cases, confirmed by reference imaging and/or follow-up. Of these, n = 22 cases were malignant changes (HCC (hepatocellular carcinoma) n = 9, CCC (cholangiocellular carcinoma) n = 3, metastases of colorectal carcinomas or recurrences of HCC n = 10). In all 12 cases of HCC or CCC, the elastography measurements using the shear wave technique (with values >2 m/s to 3.7 m/s) showed mean values of 2.3±0.31 m/s and a degree of fibrosis of F2 to F4. In n = 14 cases, changes in the fat measurement (range 0.51 to 0.72 dB/cm/MHz, mean values 0.58±0.12 dB/cm/MHz) in the sense of proportional fatty changes in the liver were detected. In the 4 cases of localized fat distribution disorders, the values were >0.7 dB/cm/MHz in the sense of significant fatty deposits in the remaining liver tissue. Relevant changes in the viscosity measurements with values >1.8 kPa were found in n = 31 cases, in n = 5 cases of cystic lesions with partially sclerosing cholangitis, in n = 13 cases of malignant lesions and in n = 9 cases post-interventionally, but also in n = 4 cases of benign foci with additional systemic inflammation. CONCLUSIONS: The results are promising and show a new quality of ultrasound-based liver diagnostics. However, there is a need for further investigations with regard to the individual aspects, preferably on a multi-center basis.

Wireless handheld ultrasound for internal jugular vein assessment in pediatric patients.

BACKGROUND: Rapid evolution of ultrasound technology has allowed widespread use of handheld ultrasound devices (HHUDs) for many possible applications. Along with the adult population, the use of HHUDs for Point of Care Ultrasound (POCUS) in pediatric medicine has been increasing over the last few years. However, pediatric-specific literature is still scarce on mobile vascular ultrasound. OBJECTIVE: To evaluate diagnostic capabilities of Vscan Air™ in comparison with high-end ultrasound for the assessment of the internal jugular vein in children and adolescents. METHODS: 42 Internal Jugular Veins (IJVs) of 21 pediatric patients were scanned by an experienced examiner using a WLAN-supported handheld ultrasound device (Vscan Air™) and high-end cart-based ultrasound (LOGIQ E9) as reference. B-Mode and Color-coded Doppler (CCDS) were performed and compared. Image quality was assessed using a score of 0 to 5 and statistically analyzed. Results were interpreted independently by two readers in consensus. RESULTS: 21 patients (2-17 years; mean 11,00±4,5 years; female n = 11, male n = 10) were examined. The rating score never dropped below 3 for both devices. The median score evaluation of B-Mode and CCDS for the high-end device was 5.00, of Vscan Air™ 5.00 for B-Mode and 4.00 for CCDS. A significant difference was shown between the two devices in the evaluation of CCDS. CONCLUSIONS: Vscan Air™ ultrasound device allows sufficient assessability of the IJV in pediatric patients, opening up new possibilities for fast and mobile POCUS of cervical veins and potential guidance of central venous catheter placement.

Sonographic 3-D Power Doppler Imaging Enhances Rapid Assessment of Morphologic and Pathologic Arteriovenous Fistula Variations.

Early detection of pathologic variations in an arteriovenous fistula (AVF) is essential for preventing fistula dysfunction in individuals undergoing hemodialysis. This study aimed to evaluate the clinical applicability of 3-D tomographic ultrasound (tUS) for rapid and simple visualization of AVF morphology and pathology. We assessed 53 AVFs in 50 consecutive patients using 3-D tUS including secondary, blinded reading. For all examinations, a high-end ultrasound (US) device was used with linear probe, attached to a tUS system to allow freehand 3-D scanning. Participants were examined by 2-D US and 3-D tUS with different raw data (B-mode, power Doppler, B-flow). Additional angiography was available for 15 participants with scheduled interventions. In all participants, 3-D tUS allowed a 3-D representation of AVFs in angiographic-like images with good image quality. The 2-D US assessment took 7.9 ± 4.0 min. A 3-D power Doppler scan required, on average, 1.4 ± 0.6 min. Diagnostic accuracy of blinded reading for pathologies was high (86.8% for aneurysms and 79.2% for stenoses). Bland-Altman plots showed an excellent correlation of 3-D tUS with 2-D US and angiography. 3-D tUS is an easily and rapidly applicable method for visualizing morphologic and pathologic AVF variations. Color-coded 3-D reconstruction of power Doppler data simplifies detection of perfused aneurysms and stenoses.

Histological and SEM Assessment of Blood Stasis in Kidney Blood Vessels after Repeated Intra-Arterial Application of Radiographic Contrast Media.

BACKGROUND: After application of iodinated contrast media (CM), a pronounced deterioration of the microcirculation in skin and myocardium was reported. Clinically, the repeated application of CM, especially, led to an increase of the renal resistance index (RRI). With respect to the transiency of the RRI increase, it is reasonable to assume that the deterioration of blood flow could be due to transient blood stasis caused by reversible morphologic cell alterations due to osmotic discrepancies between CM and human blood. Therefore, the hypothesis was investigated whether CM are able to induce in vivo such blood stasis and cell deformations in the renal vasculature of well-hydrated pigs. METHODS: The in vivo study was performed as a prospective randomized examination to compare the effects of two different CM in 16 pigs (German Landrace). Pigs were randomized to receive either Iodixanol (n = 8), or Iopromide (n = 8). Each animal received 10 injections separated by 5-min intervals via the suprarenal aorta at a rate of 10 mL/s according to the usual procedure during a cardiac catheter examination. Finally, the kidneys were explanted and processed for histology (H & E staining and fibrin staining according to Weigert) as well as for scanning electron microscopy (SEM) with regards to morphologic correlates explaining the changes in the microcirculation. RESULTS: In each of the predefined four categories of vascular diameters, blood stasis were found, but clearly more often after application of Iopromide than after application of Iodixanol (p < 0.001). In addition, Iopromide induced more blood stasis in all of the examined kidney regions compared to Iodixanol (p = 0.0001). There were no obstructive events in the middle cortex following the application of Iodixanol. Except for the region around a puncture channel of a placed-in catheter probe, no fibrin was detected in Weigert's fibrin-stained samples, neither around the histologically assessed thrombi nor in vessels with blood stasis. Complementary SEM analyses revealed in a few cases only a slight generation of fibrin and thrombi and deformations, such as echinocyte and "box-like" deformations. CONCLUSIONS: According to previous in vitro studies, pathological erythrocyte deformations, such as echinocyte and box-like formation of erythrocytes, were observed also in vivo. In addition, blood stasis and/or thrombi could be detected in histological samples from explanted kidneys from young pigs after repeated in vivo administration of CM. In only a few cases, mural platelet aggregates within minimal fibrin meshes occurred only after the application of Iopromide.

Safety margin assessment after microwave ablation of liver tumors: inter- and intrareader variability.

Background The aim of the study was to evaluate the inter- and intrareader variability of the safety margin assessment after microwave ablation of liver tumors using post-procedure computed tomography (CT) images as well as to determine the sensitivity and specificity of identification remnant tumor tissue. Patients and methods A retrospective analysis of 58 patients who underwent microwave ablation (MWA) of primary or secondary liver malignancies (46 hepatocellular carcinoma, 9 metastases of a colorectal cancer and 3 metastases of pancreatic cancer) between September 2017 and June 2019 was conducted. Three readers estimated the minimal safety margin in millimeters using side-by-side comparison of the 1-day pre-ablation CT and 1-day post-ablation CT and judged whether ablation was complete or incomplete. One reader estimated the safety margin again after 6 weeks. Magnetic resonance imaging (MRI) after 6 weeks was the gold standard. Results The intraclass correlation coefficient (ICC) for estimation of the minimal safety margin of all three readers was 0.357 (95%-confidence interval 0.194-0.522). The ICC for repeated assessment (reader 1) was 0.774 (95%-confidence interval 0.645-0.860). Sensitivity and specificity of the detection of complete tumor ablation, defined as no remnant tumor tissue in 6 weeks follow-up MRI, were 93%/82%/82% and 33%/17%/83%, respectively. Conclusions In clinical practice, the safety margin after liver tumor ablation is often assessed using side-by-side comparison of CT images. In the study, we were able to show, that this technique has a poor reliability (ICC 0.357). From our point of view, this proves the necessity of new technical procedures for the assessment of the safety distance.

Comparison between quantitative assessment of bowel wall vascularization by contrast-enhanced ultrasound and results of histopathological scoring in ulcerative colitis.

PURPOSE: In ulcerative colitis (UC), endoscopic methods are preferred for assessment of extent and activity of disease. Due to the invasive nature of endoscopical examinations, replacement by other, reliable imaging procedures would be helpful. Contrast-enhanced ultrasound (CEUS) in combination with perfusion assessment using a specific quantification software might be such a new diagnostic tool. Thus, we compared the findings of CEUS with the results of endoscopically taken specimens applying a histopathological scoring system. METHODS: We prospectively evaluated 15 patients with proven UC undergoing endoscopy. CEUS was performed and the quantification software Qontrast® applied to obtain contrast-enhanced sonographic perfusion maps. Moreover, in each patient C-reactive protein (CRP) was measured and taken biopsies were assessed using an advanced scoring system. Four patients had to be excluded from final analysis. RESULTS: There was a trend to higher Peak (%) values with increasing histological inflammation. Furthermore, a strong negative correlation between the ratio TTP (s)/Peak (%) (Spearman's correlation r = -0.761, p < 0.01) was found. There was no significant relationship between CRP and histopathological scoring or CEUS parameters, respectively. CONCLUSION: Quantitative evaluation with CEUS, particularly the calculation of the ratio TTP (s)/Peak (%), provides a simple method for assessment of inflammatory activity in UC.

Vascularization and perfusion of hepatocellular carcinoma: assessment with contrast-enhanced ultrasound using perflutren protein-type A microspheres.

PURPOSE: To assess the vascularization and the perfusion within hepatocellular carcinoma (HCC) including treatment-related changes with contrast-enhanced (CE) ultrasound (US). MATERIALS AND METHODS: Twenty-six biopsy-verified HCC lesions (size between 2.5-8 cm, median 3.8 cm) in 20 patients were examined with unenhanced and CE vascular US techniques immediately before selective angiography for transarterial chemoembolization (TACE) as well as immediately after TACE using all of the following modalities: color-coded Doppler sonography (CCDS), power Doppler imaging (PDI), CE pulse inversion harmonic imaging with PDI (PIHI+PDI), and CE coded harmonic angiography (CHA). In CE US studies, perflutren protein-type A microspheres were administered as contrast agent in a single 0.5 ml i.v. bolus diluted in 20 ml 0.9% NaCl. Selective arteriograms and CE computed tomographies were taken for reference purposes. The Wilcoxon test was used for statistical analysis. RESULTS: Intratumoral vessels could be visualized before TACE in 11/26 lesions (42%) with CCDS; in 15/26 (58%) with PDI; in 23/26 (88%) with CE CHA; in 26/26 (100%) with CE PIHI+PDI. Following TACE, the sensitivities were calculated as follows: CCDS 33%; PDI 55%; CE CHA 77%; and CE PIHI+PDI 100%. The corresponding negative predictive values were 74% for CCDS; 81% for PDI; 89% for CE CHA and 100% for CE PIHI+PDI. During the capillary phase, contrast enhancement could be observed in the CHA mode only. CONCLUSION: CE US by means of PIHI+PDI and CHA enables reliable visualization of residual tumor following TACE equivalent to that which is attained with angiography and Contrast Harmonic Imaging with Power Doppler, if perflutren microspheres are used as contrast agent in a single low-dose bolus.