Diagnostic and interventional angioscopy

Multimodal laser-based angioscopy for structural, chemical and biological imaging of atherosclerosis

The complex nature of atherosclerosis demands high-resolution approaches to identify subtle thrombogenic lesions and define the risk of plaque rupture. Here, we report the proof-of-concept use of a multimodal scanning fiber endoscope (SFE) consisting of a single optical fiber scanned by a piezoelectric drive that illuminates tissue with red, blue, and green laser beams, and digitally reconstructs images at 30 Hz with high resolution and large fields-of-view. By combining laser-induced reflectance and fluorescence emission of intrinsic fluorescent constituents in arterial tissues, the SFE allowed us to co-generate endoscopic videos with a label-free biochemical map to derive a morphological and spectral classifier capable of discriminating early, intermediate, advanced, and complicated atherosclerotic plaques. We demonstrate the capability of scanning fiber angioscopy for the molecular imaging of vulnerable atherosclerosis by targeting proteolytic activity with a fluorescent probe activated by matrix metalloproteinases. We also show that the SFE generates high-quality spectral images in vivo in an animal model with medium-sized arteries. Multimodal laser-based angioscopy could become a platform for the diagnosis, prognosis, and image-guided therapy of atherosclerosis.

Multimodal laser-based angioscopy for structural, chemical and biological imaging of atherosclerosis

The complex nature of atherosclerosis demands high-resolution approaches to identify subtle thrombogenic lesions and define the risk of plaque rupture. Here, we report the proof-of-concept use of a multimodal scanning fiber endoscope (SFE) consisting of a single optical fiber scanned by a piezoelectric drive that illuminates tissue with red, blue, and green laser beams, and digitally reconstructs images at 30 Hz with high resolution and large fields-of-view. By combining laser-induced reflectance and fluorescence emission of intrinsic fluorescent constituents in arterial tissues, the SFE allowed us to co-generate endoscopic videos with a label-free biochemical map to derive a morphological and spectral classifier capable of discriminating early, intermediate, advanced, and complicated atherosclerotic plaques. We demonstrate the capability of scanning fiber angioscopy for the molecular imaging of vulnerable atherosclerosis by targeting proteolytic activity with a fluorescent probe activated by matrix metalloproteinases. We also show that the SFE generates high-quality spectral images in vivo in an animal model with medium-sized arteries. Multimodal laser-based angioscopy could become a platform for the diagnosis, prognosis, and image-guided therapy of atherosclerosis.

Diagnostic and Interventional Optical Angioscopy in Ex Vivo Carotid Arteries

BACKGROUND: Angioscopy – or endovascular endoscopy – is a catheter-based technique employing a flexible fiberoptic angioscope to directly visualize arterial lumen. Poor resolution and excessive stiffness of pre-existent angioscopes limited their use clinically. Recent advances resulted in novel fused optical fiber bundle angioscopes with improved flexibility and imaging resolution. Use of these devices in endovascular neurosurgery is still largely unexplored.

OBJECTIVE: To evaluate image quality and feasibility of optical angioscopes for diagnostic and interventional neuro-angioscopy in carotid arteries of human cadavers.

METHODS: A 5-F optical angioscope was used in human cadaveric carotid arteries to inspect integrity of arterial walls, identify atherosclerotic plaques and associated lesions prone to thrombogenicity, place intravascular occlusion coils, and deploy endovascular stents with real-time visualization.

RESULTS: Angioscopy provided key information about endoluminal anatomy such as presence and characteristics of atherosclerotic plaques and thrombogenic lesions not detected by conventional diagnostic methods. Direct real-time visualization of vascular lumen during endovascular interventions provided information on spatial distribution of coils, coil loop herniation, and apposition of stent cells against carotid artery wall complementary to angiography.

CONCLUSIONS: Fused optical fiber bundle angioscopes provide good-quality endoluminal images in human carotid arteries. Their use can feasibly assist in navigation of extracranial carotid arteries to inspect integrity of the arterial wall and identify atherosclerotic plaques and associated lesions vulnerable to thrombogenicity, allow placement of intravascular occlusion coils, and assess apposition of stents to vessel wall. Further in Vivo validation needs to be conducted along with additional research to improve image quality, flexibility, and size of angioscopes.

IVC Thrombectomy in Renal Cell Carcinoma-Analysis of Out Come Data of 100 Patients and Review of Literature

To review our experience of RCC with IVC thrombus in terms of clinical presentation, principles of surgical management in contemporary era, also an impact of clinico-pathological factors on prognosis. Total 100 patients who underwent radical nephrectomy and IVC thrombectomy between 1991-2008 were included in this retrospective analysis. Data was analysed in terms of clinical pathological factors, survivals and compared with contemporary literature. The extent tumour thrombus was infrahepatic in 58 retro hepatic in 28 and suprahepatic in 14 patients including 6 with right atrial thrombus. The immediate postoperative mortality was 2% and incidence of major postoperative non fatal complications was 38%, which were managed conservatively. The overall and disease free 5 year survival was 63% and 55%. Further amongst the histological types, patients with clear cell tumours had the best (DFS- 71.42%), and those with papillary had the poor (DFS- 30.76%) outcome. Grade II tumors had better survivals as compared to grade IV (DFS 75.39% vs 23.52%, p < 0.05). Loco- regional extent wise 74% patients without perinephric fat invasion were free from disease at 5 years as compared to 30% of those who had perinephric fat invasion (p < 0.01). Similarly 5 year DFS was 76.11% in patients with negative nodes as compared to 12% in positive nodes (p < 0.01). In conclusion radical nephrectomy with IVC thrombectomy still remains the most effective therapeutic option in management in this clinical setting. Although this is complicated surgery success with multi disciplinary approach excellent survival outcome can be obtained. Further pathological factors, such as loco-regional spread and grade of tumor, rather than clinical factors influence long term survival.

Renal Cell Carcinoma with IVC Thrombi; Current Concepts and Future Perspectives

The incidence of venous extension to the inferior vena cava (IVC) in renal cell carcinoma (RCC) is markedly increased recently mostly due to the advances in diagnostic modalities. Such vascular invasion implies a heightened biologic behavior and a surgical challenge during the course of treatment. In this study, we reviewed the classification guidelines, recent diagnostic tools and up-to-date therapeutic modalities for RCC with IVC tumor thrombi added to the prognostic significance regarding the pathologic nature of vascular invasion; cephalad extent of thrombi and any associated distant metastasis. Also, we are providing our suggestion regarding the use of angioscopy for removal of IVC thrombi in a relatively bloodless field without aggressive surgical manipulations or shunt techniques for maintenance of hemodynamic stability.

Angioscopy

Angioscopy provides a magnified, real-time, 360-degree view of the endoluminal surface of blood vessels, yielding unique information that is often complementary to conventional angiography. This unique perspective can significantly enhance one's perception and appreciation of endovascular disease. Although angioscopy is primarily used as a research tool, its ability to characterize accurately the morphology and color of atherosclerotic lesions may lead to improved treatment and better clinical outcomes.