Therapy-induced modulation of tumor vasculature and oxygenation in a murine glioblastoma model quantified by deep learning-based feature extraction.

Glioblastoma presents characteristically with an exuberant, poorly functional vasculature that causes malperfusion, hypoxia and necrosis. Despite limited clinical efficacy, anti-angiogenesis resulting in vascular normalization remains a promising therapeutic approach. Yet, fundamental questions concerning anti-angiogenic therapy remain unanswered, partly due to the scale and resolution gap between microscopy and clinical imaging and a lack of quantitative data readouts. To what extend does treatment lead to vessel regression or vessel normalization and does it ameliorate or aggravate hypoxia? Clearly, a better understanding of the underlying mechanisms would greatly benefit the development of desperately needed improved treatment regimens. Here, using orthotopic transplantation of Gli36 cells, a widely used murine glioma model, we present a mesoscopic approach based on light sheet fluorescence microscopic imaging of wholemount stained tumors. Deep learning-based segmentation followed by automated feature extraction allowed quantitative analyses of the entire tumor vasculature and oxygenation statuses. Unexpectedly in this model, the response to both cytotoxic and anti-angiogenic therapy was dominated by vessel normalization with little evidence for vessel regression. Equally surprising, only cytotoxic therapy resulted in a significant alleviation of hypoxia. Taken together, we provide and evaluate a quantitative workflow that addresses some of the most urgent mechanistic questions in anti-angiogenic therapy.

Volumetric imaging reveals VEGF-C-dependent formation of hepatic lymph vessels in mice.

The liver is a major biosynthetic and detoxifying organ in vertebrates, but also generates 25%-50% of the lymph passing through the thoracic duct and is thereby the organ with the highest contribution to lymph flow. In contrast to its metabolic function, the role of the liver for lymph generation and composition is presently severely understudied. We took a rigorous, volume imaging-based approach to describe the microarchitecture and spatial composition of the hepatic lymphatic vasculature with cellular resolution in whole mount immune stained specimen ranging from thick sections up to entire mouse liver lobes. Here, we describe that in healthy adult livers, lymphatic vessels were exclusively located within the portal tracts, where they formed a unique, highly ramified tree. Ragged, spiky initials enmeshed the portal veins along their entire length and communicated with long lymphatic vessels that followed the path of the portal vein in close association with bile ducts. Together these lymphatic vessels formed a uniquely shaped vascular bed with a delicate architecture highly adapted to the histological structure of the liver. Unexpectedly, with the exception of short collector stretches at the porta hepatis, which we identified as exit point of the liver lymph vessels, the entire hepatic lymph vessel system was comprised of capillary lymphatic endothelial cells only. Functional experiments confirmed the space of Disse as the origin of the hepatic lymph and flow via the space of Mall to the portal lymph capillaries. After entry into the lymphatic initials, the lymph drained retrograde to the portal blood flow towards the exit at the liver hilum. Perinatally, the liver undergoes complex changes transforming from the main hematopoietic to the largest metabolic organ. We investigated the time course of lymphatic vessel development and identified the hepatic lymphatics to emerge postnatally in a process that relies on input from the VEGF-C/VERGFR-3 growth factor-receptor pair for formation of the fully articulate hepatic lymph vessel bed.

Normal thoracic aorta diameter on cardiac computed tomography in healthy asymptomatic adults: impact of age and gender.

RATIONALE AND OBJECTIVES: To establish the normal criterion of ascending aortic diameter (AAOD) measured by 64 multidetector computed tomography (MDCT) and electron beam computed tomography (EBT) based on gender and age. MATERIALS AND METHODS: A total of 1442 consecutive subjects who were referred for evaluation of possible coronary artery disease underwent coronary computed tomographic (CT) angiography (CTA) and coronary artery calcium scanning (CACS) (55 + 11 years, 65% male) without known coronary heart disease, hypertension, chronic pulmonary and renal disease, diabetes, and severe aortic calcification. The AAOD aortic diameter, descending aortic diameter (DAOD), pulmonary artery (PAD), and chest anteroposterior diameter (CAPD), posterior border of the sternal bone to the anterior border of the spine, were measured at the slice level of mid-right pulmonary artery using end systolic trigger imaging. The volume of four chambers, ejection fraction of left ventricle, and cardiac output were measured in 56% of the patients. Patients' demographic information, age, gender, weight, height, and body surface area were recorded. The mean value and age-specific and gender-adjusted upper normal limits (mean +/- 2 standard deviation) were calculated. The linear correlation analysis was done between AAOD and all parameters. The reproducibility, wall thickness, and difference between end-systole and end-diastole were calculated. RESULTS: AAOD has significant linear association with age, gender, DAOD, and pulmonary artery diameter (P < .05). There is no significant correlation between AAOD and body surface area, four-chamber volume, left ventricular ejection fraction, cardiac output, and CAPD. The mean intraluminal AAOD was 31.1 +/- 3.9 and 33.6 +/- 4.1 mm in females and males, respectively. The upper normal limits (mean +/- 2 standard deviations) of intraluminal AAOD, were 35.6, 38.3, and 40 mm for females and 37.8, 40.5, and 42.6 mm for males in age groups 20-40, 41-60, and older than 60 years, respectively. Intraluminal aortic diameters should parallel echocardiography and invasive angiography. Traditional cross-sectional imaging (with CT and magnetic resonance imaging) includes the vessel wall. The mean total AAOD was 33.5 and 36.0 mm in females and males, respectively. The upper normal limits (mean +/- 2 standard deviations) of intraluminal AAOD were 38.0, 40.7 and 42.4 mm for females and 40.2, 42.9, and 45.0 mm for males in age group 20 to 40, 41 to 60, and older than 60 years, respectively. The inter- and intraobserver, scanner, and repeated measurement variabilities were low (r value >0.91, P < .001, coefficient variation <3.2%). AAOD was 1.7 mm smaller in end-diastole than end-systole (P < .001). CONCLUSIONS: The AAOD increases with age and male gender. Gender-specific and age-adjusted normal values for aortic diameters are necessary to differentiate pathologic atherosclerotic changes in the ascending aorta. Use of intraluminal or total aortic diameter values depends on the comparison study employed.

An automated insertion tool for cochlear implants with integrated force sensing capability.

PURPOSE: Minimally invasive cochlear implantation and residual hearing preservation require both the surgical approach to the cochlea as well as the implant insertion to be performed in an atraumatic fashion. Considering the geometric limitations of this approach, specialized instrumentation is required to insert the electrode while preserving intracochlear membranes carrying the sensory hair cells. METHODS: An automated insertion tool for cochlear implants, which is capable of sensing insertion forces with a theoretical resolution of 30 µN, is presented. In contrast to previous designs, the custom force sensor is integrated in the insertion mechanism. Moreover, a test bench for insertion studies under constant and reproducible boundary conditions is proposed. It is used to experimentally validate the force sensing insertion tool, which is achieved by comparing the acquired forces to a ground truth measurement. The results of insertion studies on both an acrylic cochlear phantom and temporal bone specimen are given and discussed. RESULTS: Results reveal that friction, occurring between the electrode carrier and the inside of the insertion tool guide tube, is likely to affect the force output of the proposed sensor. An appropriate method to compensate for these disturbances is presented and experimentally validated. Using the proposed approach to friction identification, a mean accuracy of (4.0±3.2) mN is observed. CONCLUSIONS: The force information provided by the proposed, automated insertion tool can be used to detect complications during electrode insertion. However, in order to obtain accurate results, an identification of frictional forces prior to insertion is mandatory. The insertion tool is capable of automatically executing the appropriate trajectories.