A novel gas embolotherapy using microbubbles electrocoalescence for cancer treatment

BACKGROUND AND OBJECTIVE

Embolotherapy has been increasingly used to disrupt tumor growth. Despite its success in the occlusion of microvessels, it has drawbacks such as limited access to the target location, limited control of the blocker size, and inattention to the tumor characteristics, especially high interstitial fluid pressure. The present work introduces a novel numerical method of gas embolotherapy for cancer treatment through tumor vessel occlusion.

METHODS

The gas microbubbles are generated from Levovist bolus injection into the tumor microvessel. The microbubble movement in the blood flow is innovatively controlled by an electric field applied to the tumor-feeding vessel. The interaction between the Levovist microbubbles and the electric field is resolved by developing a fully coupled model using the phase-field model, Carreau model for non-Newtonian blood, Navier-Stokes equations and Maxwell stress tensor. Additionally, the critical effect of high interstitial fluid pressure as a characteristic of solid tumors is included.

RESULTS

The findings of this study indicate that the rates of microbubble deformation and displacement increase with the applied potential intensity to the microvessel wall. Accordingly, the required time for a microbubble to join the upper microvessel wall reduces from 1.97ms to 22 μs with an increase of the electric potential from 3.5V to 12.5V. Additionally, an electric potential of 12.5V causes the microbubbles coalescence and formation of a gas column against the bloodstream.

CONCLUSIONS

Clinically, our novel embolization procedure can be considered a non-invasive targeted therapy, and under a controlled electric field, the blocker size can be precisely controlled. Also, the proposed method has the potential to be used as a gradual treatment in advanced cancers as tumors develop resistance and relapse.

Contrast-Enhanced Ultrasonography (CEUS) in Imaging of the Reproductive System in Dogs: A Literature Review

The use of contrast-enhanced ultrasound (CEUS) has been widely reported for reproductive imaging in humans and animals. This review aims to analyze the utility of CEUS in characterizing canine reproductive physiology and pathologies. In September 2022, a search for articles about CEUS in canine testicles, prostate, uterus, placenta, and mammary glands was conducted on PubMed and Scopus from 1990 to 2022, showing 36 total results. CEUS differentiated testicular abnormalities and neoplastic lesions, but it could not characterize tumors. In prostatic diseases, CEUS in dogs was widely studied in animal models for prostatic cancer treatment. In veterinary medicine, this diagnostic tool could distinguish prostatic adenocarcinomas. In ovaries, CEUS differentiated the follicular phases. In CEH-pyometra syndrome, it showed a different enhancement between endometrium and cysts, and highlighted angiogenesis. CEUS was shown to be safe in pregnant dogs and was able to assess normal and abnormal fetal-maternal blood flow and placental dysfunction. In normal mammary glands, CEUS showed vascularization only in diestrus, with differences between mammary glands. CEUS was not specific for neoplastic versus non-neoplastic masses and for benign tumors, except for complex carcinomas and neoplastic vascularization. Works on CEUS showed its usefulness in a wide spectrum of pathologies of this non-invasive, reliable diagnostic procedure.

Recent Imaging Updates and Advances in Gynecologic Malignancies

Gynecologic malignancies are among the most common cancers in women worldwide and account for significant morbidity and mortality. Management and consequently overall patient survival is reliant upon early detection, accurate staging and early detection of any recurrence. Ultrasound, Computed Tomography (CT), Magnetic resonance imaging (MRI) and Positron Emission Tomography-Computed Tomography (PET-CT) play an essential role in the detection, characterization, staging and restaging of the most common gynecologic malignancies, namely the cervical, endometrial and ovarian malignancies. Recent advances in imaging including functional MRI, hybrid imaging with Positron Emission Tomography (PET/MRI) contribute even more to lesion specification and overall role of imaging in gynecologic malignancies. Radiomics is a neoteric approach which aspires to enhance decision support by extracting quantitative information from radiological imaging.

Contrast-enhanced ultrasound evaluation of placental perfusion in brachicephalic bitches

The present study aimed to investigate placental hemodynamics to determine quantitative and qualitative parameters for pregnant brachycephalic bitches as well as describe placental vascularization and perfusion in females with fetal abnormalities close to delivery. Forty-four healthy fetuses from 22 brachycephalic bitches and 9 fetuses with gestational abnormalities (anasarca and hydrocephalus) from 8 brachycephalic bitches were evaluated. All female dogs were artificially inseminated intravaginally and underwent cesarean section at the end of gestation. Pregnancy diagnosis was made on the 25th day and experimental evaluations were performed on Days 25 (M1), 45 (M2), and 58 (M3) of gestation in normal pregnancies. Fetuses with gestational abnormalities were evaluated at the last time point. Biometric values of the fetuses were determined by B-mode and vascular indices by Doppler fluxometry of the umbilical artery, whereas qualitative assessment of contrast filling and quantitative parameters of placental perfusion were performed using CEUS. Parameter comparisons among the examined fetuses (normal and abnormal) and between the moments (M1, M2, and M3) were performed by Student's t-test and ANOVA tests, and then correlated using the Spearman test. In healthy fetuses, systolic and diastolic velocities as well as the time averages of minimum and maximum velocities increased significantly from M2 to M3 (P < 0.05), whereas the pulsatility index (P < 0.043) and vascular resistance (P < 0.001) decreased. Contrast distribution was always homogeneous in placental tissues and CEUS filling parameters remained constant during the evaluated periods (P < 0.05). In fetuses with hydrops, Doppler values were similar to those obtained in healthy subjects (P > 0.05), but CEUS evaluation demonstrated a heterogeneous distribution with lower intensity of placental tissue filling and a delay in perfusion time (P < 0.05) with a diagnostic accuracy of 75%. The association of dopplerfluxometry and CEUS allowed evaluation of qualitative and quantitative parameters of physiological pregnancy hemodynamics in all gestational thirds without evidence of significant changes in the physiology of the maternal-fetal binomial, and CEUS was shown to be applicable in the detection of failures in placental vascular filling (tissue dysfunction) in fetuses with anasarca and hydrocephaly.

Contrast-Enhanced Ultrasound in Cystic Endometrial Hyperplasia-Pyometra Complex in the Bitch: A Preliminary Study

Simple Summary

In canine cystic endometrial hyperplasia–pyometra (CEH) syndrome, toxic factors and endometrial inflammatory reactions are responsible of increased blood flow and lower vascular resistance in uterine arteries. Color Doppler ultrasound is regarded as an adjunctive tool for quantitative assessment of endometrial vascularization during uterine disorders. The aim of this study was to assess, through contrast-enhanced ultrasound (CEUS) exam, the vascularization in endometrial microvessels in CEH-pyometra in order to evaluate the possibility of application in this syndrome. In twelve female dogs with clinical symptoms related to pyometra, echographic, Color Doppler and CEUS exams were performed. Histopathological examination revealed severe CEH and pyometra, immunohistochemical stain with CD 34 confirmed the presence of angiogenesis. CEUS exam revealed a widespread, intense and rapidly developing homogeneous enhancement of the hyperplastic endometrium with absence of signal only in cystic areas. All parameters of the quantitative analysis were not significantly influenced by region of interest dimension and position. CEUS may improve not invasive evaluations in the CEH-pyometra syndrome and virtually in CEH-mucometra.

Abstract

In cystic endometrial hyperplasia (CEH)–pyometra syndrome, toxic factors and endometrial remodeling culminate in changes characterized by exudative and degenerative inflammatory reaction. Recent studies on hemodynamic found an increased blood flow and lower vascular resistance in uterine arteries, suggesting color Doppler ultrasound as an adjunctive tool for quantitative assessment of endometrial vascularization during pyometra. The aim of this study was to assess, through contrast-enhanced ultrasound (CEUS) exam, the vascularization in endometrial microvessels in CEH-pyometra in order to evaluate the possibility of application in this syndrome. In twelve female dogs with clinical symptoms related to pyometra, B-mode, color Doppler and CEUS exams were performed. In CEH-pyometra uteri, histopathological examination revealed severe CEH and pyometra, immunohistochemical stain with CD 34 confirmed the presence of angiogenesis. CEUS exams revealed a widespread, intense and rapidly developing homogeneous enhancement of the hyperplastic endometrium, with absence of signal only in cystic areas. All parameters of the quantitative analysis were not significantly influenced by region of interest dimension and position. CEUS has the potential to improve clinical not invasive evaluations in the CEH-pyometra syndrome and virtually in CEH-mucometra.

Diagnostic imaging in pregnancy: Making informed decisions

The use of diagnostic imaging involving ionising radiation may be necessary in pregnancy and requires an assessment of the most appropriate and safest imaging modality which will provide the necessary information balanced with the potential risks to the mother and fetus. In most cases, this will involve a potential fetal radiation dose well below 50 mGy. At these doses, there is no risk of lethality, genetic damage/epigenetic change, teratogenicity, growth impairment or sterility. Older epidemiological data indicating a potential increased cancer risk have been contradicted by newer data and better understanding of the biology of low dose radiation. The linear no-threshold rule has been challenged by many and more realistic estimates of oncogenicity risk along with the potential risks of contrast agents are summarised in this review. Imaging in the pregnant population is increasing in both the number of examinations performed and the number of patients being imaged, with the greatest increase being computed tomography scans. Counselling and obtaining informed consent for imaging that involves radiation requires the clinician to communicate with the woman and her family a realistic estimate of the potential radiation dose to herself and her fetus, to describe and quantitate the risks of this estimated dose, to outline the benefits of the imaging procedure and to respond to any questions or concerns. As almost all diagnostic imaging involves doses below the 50 mGy threshold, clinically indicated investigations should not be withheld during pregnancy. All allied staff must also be well informed to ensure the patient receives a consistent message about the risks and benefits of the proposed test.

Contrast-enhanced ultrasonography of maternal and fetal blood flows in pregnant bitches

We evaluated the potential usefulness of CEUS to assess fetal-maternal circulation during pregnancy in dogs. Nine bitches were examined at 23, 30, and 45 days of gestation using an ultrasound machine (LOGIQ E9) and SonoVue^® contrast media as echo-signal enhancer. Qualitative and quantitative evaluation of contrast enhancement patterns of uterine artery and utero/placental vessels were performed on recorded images. Independently of the gestational periods, the qualitative evaluation showed the initial wash-in phase from the first appearance of the uterine artery to the rapid distribution in embryonic vesicles or placenta to the progressive washout, whilst there was no enhancement of either embryos or fetuses in any bitch. Independent of gestational age, parameters derived from quantitative analysis of time intensity-curves of contrast enhancement (peak intensity, time to peak, rise time, washout) did not vary between proximal placenta, distal placenta, and uterine artery. With the progression of gestation, AUC values did not change in both proximal and distal placenta, but in the uterine artery it was lower (P ≤ 0.05) at day 30 than at day 23 (464.8 ± 16.1 vs.596.4 ± 28.1, respectively). In conclusion, CEUS appears to safely permit evaluation of the maternal and fetal vessels in the first two third of gestation, without any clinically relevant adverse effects. Further studies in a larger number of bitches in different stages of pregnancy are needed to establish standard parameters for normal pregnancies that can be used to detect abnormalities of pregnancy.