Acoustic and Elastic Properties of a Blood Clot during Microbubble-Enhanced Sonothrombolysis: Hardening of the Clot with Inertial Cavitation.

Stroke is the second leading cause of death worldwide. Existing therapies present limitations, and other therapeutic alternatives are sought, such as sonothrombolysis with microbubbles (STL). The aim of this study was to evaluate the change induced by STL with or without recombinant tissue-type plasminogen activator (rtPA) on the acoustic and elastic properties of the blood clot by measuring its sound speed (SoS) and shear wave speed (SWS) with high frequency ultrasound and ultrafast imaging, respectively. An in-vitro setup was used and human blood clots were submitted to a combination of microbubbles and rtPA. The results demonstrate that STL induces a raise of SoS in the blood clot, specifically when combined with rtPA (p < 0.05). Moreover, the combination of rtPA and STL induces a hardening of the clot in comparison to rtPA alone (p < 0.05). This is the first assessment of acoustoelastic properties of blood clots during STL. The combination of rtPA and STL induce SoS and hardening of the clot, which is known to impair the penetration of thrombolytic drugs and their efficacy.

Quantitative Ultrasound in Ex Vivo Fibrotic Rabbit Livers.

Liver fibrosis is the common result of chronic liver disease. Diagnosis and grading liver fibrosis for patient management is mainly based on blood tests and hepatic puncture-biopsy, which is particularly invasive. Quantitative ultrasound (QUS) techniques provide insight into tissue microstructure and are based on the frequency-based analysis of the signals from biologic tissues. This study aims to quantify how spectral-based QUS parameters change with fibrosis grade. The changes in QUS parameters of healthy and fibrotic rabbit liver samples were investigated and were compared with the changes in liver stiffness, using shear wave elastography. Overall, the acoustic concentration was found to decrease with increasing fibrosis grade, and the effective scatterer size was found to be higher in fibrotic livers when compared with normal liver. The result of this study indicates that the combination of three QUS parameters (stiffness, effective scatterer size and acoustic concentration) provides the best classification performance, especially for classifying healthy and fibrotic livers.

Microbubbles combined with ultrasound therapy in ischemic stroke: A systematic review of in-vivo preclinical studies.

BACKGROUND: Microbubbles (MBs) combined with ultrasound sonothrombolysis (STL) appears to be an alternative therapeutic strategy for acute ischemic stroke (IS), but clinical results remain controversial. OBJECTIVE: The aim of this systematic review is to identify the parameters tested; to assess evidence on the safety and efficacy on preclinical data on STL; and to assess the validity and publication bias. METHODS: Pubmed® and Web of ScienceTM databases were systematically searched from January 1995 to April 2017 in French and English. We included studies evaluating STL on animal stroke model. This systematic review was conducted in accordance with the PRISMA guidelines. Data were extracted following a pre-defined schedule by two of the authors. The CAMARADES criteria were used for quality assessment. A narrative synthesis was conducted. RESULTS: Sixteen studies met the inclusion criteria. The result showed that ultrasound parameters and types of MBs were heterogeneous among studies. Numerous positive outcomes on efficacy were found, but only four studies demonstrated superiority of STL versus recombinant tissue-type plasminogen activator on clinical criteria. Data available on safety are limited. LIMITATIONS: Quality assessment of the studies reviewed revealed a number of biases. CONCLUSION: Further in vivo studies are needed to demonstrate a better efficacy and safety of STL compared to currently approved therapeutic options. SYSTEMATIC REVIEW REGISTRATION: http://syrf.org.uk/protocols/.

Evaluation of high resolution ultrasound as a tool for assessing the 3D volume of blood clots during in vitro thrombolysis.

Thrombosis is a major cause of several diseases, i.e. myocardial infarction, cerebral stroke and pulmonary embolism. Thrombolytic therapies are required to induce fast and efficient recanalization of occluded vessels. To evaluate the in vitro efficacy of these thrombolytic strategies, measuring clot dissolution is essential. This study aimed to evaluate and validate high resolution ultrasound as a tool to assess the exact volume of clots in 3D and in real time during in vitro thrombolytic drug testing. This new method was validated by measuring the effects of concentration range of recombinant tissue type plasminogen activator on a blood clot during complete occlusion or 70% stenosis of a vessel. This study shows that high resolution ultrasound imaging allows for a real-time assessment of the 3D volume of a blood clot with negligible inter- and intra-operator variabilities. The conclusions drawn from this study demonstrate the promising potential of high resolution ultrasound imaging for the in vitro assessment of new thrombolytic drugs.

Microbubble-mediated ultrasound drug-delivery and therapeutic monitoring.

INTRODUCTION: Recent developments in ultrasound imaging and ultrasound contrast agents (UCAs) improved diagnostic confidence in echography and set into motion their combined use as a tool for drug delivery and therapeutic monitoring. Non-invasive, precise and targeted delivery of drug molecules to pathological tissues by employing different mechanisms of drug release is becoming feasible. Areas covered: We sought to describe: the nature and features of UCAs; outline current contrast-specific imaging modes; before describing a variety of strategies for using ultrasound and microbubbles as a drug delivery system. Our expert opinion focusses on results and prospects of using ultrasound and microbubbles as a dual modality for drug delivery and therapeutic monitoring. Expert opinion: Today, ultrasound and microbubbles present a realistic prospect as drug delivery tools that have been demonstrated in a variety of animal models and clinical indications. Besides delivering drugs, ultrasound and microbubbles have demonstrated added value through therapeutic monitoring and assessment. Successful evaluation of the sonoporation mechanism(s), ultrasound parameters, drug type and dose will need to be addressed before translating this technology for clinic use. Ultimately, the development of a strategy for monitoring targeted delivery and its implementation in clinical practice would advance therapeutic treatment to a new qualitative level.

Prevalence of Raynaud phenomenon and nailfold capillaroscopic abnormalities in Fabry disease: a cross-sectional study.

Fabry disease (FD) is a lysosomal disorder leading to progressive systemic involvement, including microvascular damage that leads to neurological and cardiovascular disorders. We hypothesize that the latter could be documented at an early stage by performing a microcirculation study with nailfold capillaroscopy and evaluation of Raynaud phenomenon.The objective was to measure the prevalence of Raynaud phenomenon and nailfold capillaroscopic abnormalities in FD.This cross-sectional study included a standardized questionnaire and a nailfold capillaroscopy that assessed previously reported patterns in FD (dystrophic and giant capillaries, avascular fields, irregular architecture, dilatation and density of capillaries, hemorrhage), and was conducted on 32 Fabry patients and 39 controls. Capillaroscopic photographs were reviewed by 2 independent blinded investigators.Twelve Fabry patients (38%) suffered from Raynaud phenomenon, 5 were males (ie, 50% of male Fabry patients), compared with 2 controls (13%) (P < 0.001), of whom none were males (P < 0.001). Raynaud phenomenon was concomitant or before the occurrence of pain in the extremities in 42% of Fabry patients.More ramified capillaries were significantly observed in Fabry patients (12/32, 38%) than in controls (5/39, 13%, P = 0.016).Secondary Raynaud phenomenon should lead to screening for FD, especially in men. By extension, in high-risk populations for FD, the presence of Raynaud phenomenon and ramified capillaries should be assessed.

Idiopathic hypertrophic pachymeningitis presenting with occipital neuralgia.

BACKGROUND: Although occipital neuralgia is usually caused by degenerative arthropathy, nearly 20 other aetiologies may lead to this condition. METHODS: We present the first case report of hypertrophic pachymeningitis revealed by isolated occipital neuralgia. RESULTS AND CONCLUSIONS: Idiopathic hypertrophic pachymeningitis is a plausible cause of occipital neuralgia and may present without cranial-nerve palsy. There is no consensus on the treatment for idiopathic hypertrophic pachymeningitis, but the usual approach is to start corticotherapy and then to add immunosuppressants. When occipital neuralgia is not clinically isolated or when a first-line treatment fails, another disease diagnosis should be considered. However, the cost effectiveness of extended investigations needs to be considered.

Ischemic stroke due to paradoxical embolism arising from a popliteal vein aneurysm.

Popliteal vein aneurysm (PVA) is a very uncommon cause of stroke. We present the case of a 63-year-old, right-handed man who presented to the emergency department with transitory ischemic accident (left superior extremity regressive monoplegia). Complete etiologic work-up led to the discovery of both a patent foramen ovale associated with an septum interauricular aneurysm, and of a PVA without mural thrombus. The diagnosis of brain paradoxical embolism was retained. The unique potentially embolic cause was the presence of the PVA. We decided to treat the PVA surgically to avoid a further cerebral vascular episode. Although uncommon, venous etiology must be considered for stroke.