Quantitative Vessel Analysis Research Articles

Computer-aided detection of retinopathy of prematurity severity assessment via vessel tortuosity measurement in preterm infants' fundus images.

To develop a computer-aided diagnostic system for retinopathy of prematurity (ROP) disease using retinal vessel morphological features. A total of 200 fundus images from 136 preterm infants with stage 1 to 3 ROP were analysed. Two methods were developed to measure vessel tortuosity: the peak-and-valley method and the polynomial curve fitting method. Correlations between temporal artery tortuosity (TAT) and temporal vein tortuosity (TVT) with ROP severity were investigated, and vessel tortuosity relationships with vessel angles (TAA and TVA) and vessel widths (TAW and TVW). A separate dataset from Japan containing 126 images from 97 preterm patients was used for verification. Both methods identified similar tortuosity in images without ROP and mild ROP cases. However, the polynomial curve fit method demonstrated enhanced tortuosity detection in stages 2 and 3 ROP compared to the peak and valley method. A strong positive correlation was revealed between ROP severity and increased arterial and venous tortuosity (P < 0.0001). A significant negative correlation between TAA and TAT (r = -0.485, P < 0.0001) and TVA and TVT (r = -0.281, P < 0.0001), and a significant positive correlation between TAW and TAT (r = 0.204, P value = 0.0040) were identified. Similar results were found in the test dataset from Japan. ROP severity was associated with increased retinal tortuosity and retinal vessel width while displaying a decrease in retinal vascular angle. This quantitative analysis of retinal vessels provides crucial insights for advancing ROP diagnosis and understanding its progression.

관상동맥 CT와 심근관류 CT 검사를 이용한 고농도 조영제와 저농도 조영제 간 비교 평가

With the advancement of CT technology, the use of low tube voltages, and the clinical efficacy of low-concentration contrast media are gradually being demonstrated. In this study, we compared the differences between high- and low-concentration contrast media using Coronary Computed Tomography Angiography (CCTA) and Computed Tomography-Myocardial Perfusion Imaging (CT-MPI). These imaging techniques can simultaneously evaluate the patient's hemodynamic distribution and myocardium. The study results indicated that the quantitative analysis of tissues and blood vessels in CCTA showed that high-concentration contrast media led to a 5 to 10% increase in Hounsfield Units (HU), but the probability of significance was greater than 0.05. As a result of myocardial evaluation using CCTA and CT-MPI, the difference between the two contrast agents was within 5%, and the probability of significance was greater than 0.05. Qualitative analysis utilized nominal measurements in five categories and did not reveal significant differences between low- and high-concentration contrast media with a significance probability greater than 0.05. This study differed from existing studies by utilizing high- and low-concentration contrast media for CCTA and CT-MPI examinations. Analysis using CCTA and CT-MPI shows that low-concentration images are not inferior to images obtained using high-concentration contrast media.

Quantitative Analysis of Occipital Artery Bypass Donor Vessels by Ultrasonography and DSA.

Occipital artery (OA) acts as a vital donor vessel in intra-cranialand extra-cranial bypass. Ultrasonography and digital subtracted angiography (DSA) are becoming increasingly important in the assessment of vascular morphology and hemodynamically; however, quantitative analysis of occipital artery bypass donor vessels by Ultrasonography and DSA are seldom discussed. A retrospective study involving 62 cases accepted occipital artery bypass to treat posterior circulation aneurysms or artery occlusion/stenosis. The characteristics of OA are collected and analyzed. Occipital artery bypasses were performed to treat posterior circulation aneurysms in 34 patients and to treat posterior circulation artery occlusion or stenosis in 28 patients. Compared with the ultrasonography group, the DSA group had a greater diameter of OA, and Bland Altman analysis indicated that the discrepancy between the 2 groups was about 0.555 mm. Ultrasonography showed the characteristics of OA: the mean Peak Systolic Velocity (PSV) was 42.98 cm/s, the mean End Diastolic Velocity (EDV) was 8.811 cm/s, and the mean Resistance Index (RI) was 1.46. There were no statistical differences in the diameter of OA, PSV, EDV, and RI between the male group and female group, the elderly group and younger adult group or the left occipital artery group and right occipital artery group. However, compared with patients with posterior circulation aneurysms, patients with artery occlusion or stenosis were older and had higher PSV, RI, and greater diameter in occipital arteries. The mean diameter of occipital arteries was increased in the first postoperative years but reduced in 3 patients during 1 year follow-up. Both ultrasonography and DSA were effective assessment methods of occipital artery bypasses, and the DSA group had a greater diameter of OA. Age, gender, and left or right sides had little effect on the diameter of OA, PSV, EDV, and RI. Posterior circulation occlusion or stenosis had higher PSV, RI, and greater diameter of the occipital artery when compared with posterior circulation aneurysms. Occipital artery bypasses could increase the diameter of OA in most cases.

Quantitative Analysis of Bone, Blood Vessels, and Metastases in Mice Tibiae Using Synchrotron Radiation Micro-Computed Tomography

Bone metastases are one of the most dangerous consequences of breast cancer. Early diagnosis and treatment would slow down the development of the disease and increase the survival rates of patients. Bone micro-vasculature is believed to play a major role in the development of bone metastases. It could be used for both diagnosis and as a therapeutic target. Synchrotron radiation micro-computed tomography (SR-µCT) with a contrast agent of blood vessels has been used to analyze the bone vasculature both in healthy and in metastatic bone. However, few studies have investigated the local features of blood vessels around metastases so far. For this purpose, the metastases first need to be automatically segmented. This is a challenging task, however, since the metastases do not contribute a specific contrast to the three-dimensional (3D) SR-µCT images. Here, we propose a new method for the simultaneous segmentation of bone, blood vessels, and metastases from contrast enhanced 3D SR-µCT images based on the nnU-Net architecture. In this study, we showed that only minimal training data was required to achieve a high quality of segmentation. The proposed method allowed for the automatic segmentation of metastases and provided an improved segmentation of bone and blood vessels compared to previous methods while being much more efficient to apply once trained. Further, the automatic segmentation allowed for the measurement of vascular metastases interdistance and to restrict measurements to volumes of interest around the metastases. Finally, we quantitatively analyzed blood vessel parameters locally around metastases. This allowed for the demonstration that a combined anti-angiogenic treatment significantly decreased the volume and thickness of blood vessels close to metastases. The proposed method showed the capacity of the method to reveal new aspects of the blood vessel structure interaction with metastases. This could be further used to both define new targets for precocious detection of metastases as well as to study the kinetics of metastasis development in bone and the action of drugs on this process.

Clinical Research of Lupus Retinopathy: Quantitative Analysis of Retinal Vessels by Optical Coherence Tomography Angiography in Patients with Systemic Lupus Erythematosus.

Lupus retinopathy, an ocular manifestation of systemic lupus erythematosus (SLE), is the major pathology attributed to retinal vasculopathy. Our study is to analyze the changes in retinal vessels in patients with SLE by optical coherence tomography angiography. A total of 61 SLE patients without obvious retinal manifestation and 71 healthy people were included. The SLE patients were further divided into a lupus nephritis (LN) group and a non-LN group. The changes in central macular thickness (CMT) and the retinal vessel densities were compared between the two groups, and the correlation between retinal vascular changes and disease activity was analyzed. Compared with healthy control, the CMT and the retinal vascular densities in both superficial and deep retina were decreased significantly in SLE patients. There was no significant difference in retinal vascular densities between LN groups and non-LN groups. The CMT and retinal vessel densities were decreased in SLE patients without clinical manifestations, which might serve as a sensitive biomarker for early changes of lupus retinopathy in SLE patients.

Correlation Between Intranodular Vessels and Tumor Invasiveness of Lung Adenocarcinoma Presenting as Ground-glass Nodules: A Deep Learning 3-Dimensional Reconstruction Algorithm-based Quantitative Analysis on Noncontrast Computed Tomography Images.

To evaluate the role of quantitative features of intranodular vessels based on deep learning in distinguishing pulmonary adenocarcinoma invasiveness. This retrospective study included 512 confirmed ground-glass nodules from 474 patients with 241 precursor glandular lesions (PGL), 126 minimally invasive adenocarcinomas (MIA), and 145 invasive adenocarcinomas (IAC). The pulmonary blood vessels were reconstructed on noncontrast computed tomography images using deep learning-based region-segmentation and region-growing techniques. The presence of intranodular vessels was evaluated based on the automatic calculation of vessel prevalence, vascular categories, and vessel volume percentage. Further comparisons were made between different invasive groups by the Mantel-Haenszel χ 2 test, χ 2 test, and analysis of variance. The detection rate of intranodular vessels in PGL (33.2%) was significantly lower than that of MIA (46.8%, P = 0.011) and IAC (55.2%, P < 0.001), while the vascular categories were similar (all P > 0.05). Vascular changes were more common in IAC and MIA than in PGL, mainly in increased vessel volume percentage (12.4 ± 19.0% vs. 6.3 ± 13.1% vs. 3.9 ± 9.4%, P < 0.001). The average intranodular artery and vein volume percentage of IAC (7.5 ± 14.0% and 5.0 ± 10.1%) was higher than that of PGL (2.1 ± 6.9% and 1.7 ± 5.8%) and MIA (3.2 ± 9.1% and 3.1 ± 8.7%), with statistical significance (all P < 0.05). The quantitative analysis of intranodular vessels on noncontrast computed tomography images demonstrated that the ground-glass nodules with increased internal vessel prevalence and volume percentages had higher possibility of tumor invasiveness.

Quantitative analysis of external carotid artery bypass donor vessels by recipient and approach

IntroductionUtilization an in-situ pedicle of the external carotid artery (ECA) as an arterial donor can allow for the successful augmentation or replacement of flow to a large vascular territory. We propose a mathematical model for quantitatively analyzing and grading the suitability of donor and recipient bypass vessels based on a set of anatomical and surgical variables in order to predict which pair has the greatest possibility for success. Using this method, we analyze all of the potential donor-recipient pairs for each ECA donor vessel—including the superficial temporal (STA), middle meningeal (MMA), and occipital (OA) arteries. MethodsThe ECA pedicles were dissected in frontotemporal, middle fossa, subtemporal, retrosigmoid, far lateral, suboccipital, supracerebellar, and occipital transtentorial approaches. For each approach, every potential donor-recipient pair was identified, and donor length and diameter were measured as well as depth of field, angle of exposure, ease of proximal control, maneuverability, and length and diameter of the recipient segment. Anastomotic pair scores were determined by adding the weighted donor and recipient. ResultsThe best overall anastomotic pairs were OA-vertebral artery (V3, 17.1) and STA-insular (M2, 16.3) and STA-sylvian (M3, 15.9) segments of the middle cerebral artery. Other strong anastomotic combinations were OA- telovelotonsillar (15) and OA- tonsilomedullary (14.9) segments of the posterior inferior cerebellar artery, and MMA-lateral pontomesencephalic segment of the superior cerebellar artery (14.2). ConclusionsThis novel model for anastamotic pair scoring can serve as a useful clinical tool for selecting the optimal donor, recipient, and approach combination that can help facilitate a successful bypass.

Choroidal vessel segmentation in SD-OCT with 3D Shape-aware Adversarial Networks

Background and Objective:Quantitative analysis of choroidal vessels is important for the diagnosis of choroidal related diseases and the cognition of the choroid. Previous studies focused on segmenting choroidal vessels in enhanced depth imaging optical coherence tomography (OCT) and swept-source OCT modalities. There is still a blank for the segmentation of 3D choroidal vessels in the spectral-domain OCT (SD-OCT) modality. Quantitative analysis of choroidal vessels is crucial for diagnosing choroidal-related diseases and understanding the choroid. Previous studies have focused on segmenting choroidal vessels in enhanced depth imaging optical coherence tomography (OCT) and swept-source OCT modalities. There is still a gap in the segmentation of 3D choroidal vessels in the spectral-domain OCT (SD-OCT) modality. Method:We propose a novel 3D CNN-based method, called Shape-aware Adversarial Networks (SAN), for segmenting choroidal vessels in SD-OCT images. To learn the 3D mapping of SD-OCT images and labels, we built a 3D U-shape network backbone with anisotropic down-sampling and up-sampling operations. To learn the morphological characteristics of choroidal vessels, we constructed an auxiliary output branch to predict a newly designed choroidal vessel shape representation generated by labels. We further introduced a label-conditional adversarial loss to enforce shape learning in a patch-based pipeline. The code for SAN is publicly available at: https://github.com/nicetomeetu21/SAN. Results:The effectiveness of SAN has been verified in data with myopia. The proposed model reported as measures of segmentation performance a mean dice similarity coefficient of 85.96% and a mean Hausdorff distance of 2.54, outperforming other 2D and 3D segmentation methods. We further applied our method in the statistical analysis of the choroidal feature between 100 eyes with low to moderate myopia and 108 eyes with high myopia. The results show that in all Early Treatment of Diabetic Retinopathy Study subfields, the choroid volumes and vascular volumes of the two groups are significantly different (P<0.01). The choroidal vascular indexes (CVI) of two groups are significantly different in most subfields (P<0.01) except for central and nasal inner subfields. The CVI of the high myopia group is higher than that of the low to moderate myopia group in most subfields except for the nasal inner subfield. Conclusions:The results demonstrate that the proposed method can accurately segment choroidal vessels from SD-OCT volumes. The quantitative analysis of choroidal biomarkers in a total of 208 myopia eyes shows the applicability of the proposed method in helping to study the choroid.

Five-Year Outcomes of the Bioresorbable Peripheral Remedy Stent in the Treatment of Iliac Artery Disease

PurposeTo evaluate the 5-year performance of a bioresorbable vascular scaffold, the Remedy stent, for the treatment of iliac artery atherosclerotic disease. Materials and MethodsThis prospective, multicenter, single-arm clinical study evaluated 97 patients (97 lesions) with symptomatic TransAtlantic Inter-Society Consensus II A/B iliac artery lesions for 5 years after stent placement. The primary efficacy end point was 12-month primary patency compared with the prespecified standard derived from historical data with metallic stents, and the primary safety end point was the occurrence of major adverse clinical events within 5 years. All angiographic and computed tomography angiographic findings were evaluated by an independent core laboratory for quantitative vessel analysis. ResultsThe 12-month primary patency rate was 88.6% (95% CI, 80.1%–94.4%), which was lower than the prespecified standard. No significant difference was noted between the diameter stenosis at 9 and 12 months. There were no device- or procedure-related deaths, major amputation, or distal embolization during the follow-up period. The ankle-brachial index maintained significant improvement through the 5-year period compared with that at baseline. The Kaplan–Meier estimates of freedom from target lesion revascularization (TLR), major adverse cardiovascular events, and major adverse cardiovascular and limb events were 95.8%, 91.7%, and 87.5% at 12 months and 85.4%, 72.1%, and 62.5% at 5 years, respectively. ConclusionsThe 5-year follow-up outcomes, including freedom from TLR, of the Remedy stent in iliac artery lesions were satisfactory, with a good safety profile. Nevertheless, the 12-month primary patency did not meet the expected standard compared with that of contemporary metallic stents.

Heterogeneous vascular response after implantation of bare nitinol self-expanding stents in the swine femoropopliteal artery

BackgroundMechanism of femoropopliteal in-stent restenosis has been underappreciated.AimThe aim of this animal study was to elucidate vascular response after femoropopliteal bare nitinol self-expanding stents (SESs) implantation.MethodsMisago, Smart Flex, or Innova stent was randomly implanted in 36 swine femoropopliteal arteries. At week 4, quantitative vessel analysis (QVA) was performed on 36 legs, of which 18 underwent histological evaluation after angiography. The remaining 18 legs underwent QVA and histological evaluation at week 13.ResultsFibrin deposition was excessive at week 4. Internal elastic lamina (IEL) progressively enlarged over time, and vessel injury developed from mild level at week 4 to moderate level at week 13. Vessel inflammatory reaction was mild to moderate at week 4, and was moderate to severe at week 13. Increased fibrin deposition was an early-acting, IEL enlargement and increased vessel inflammation were long-acting, and increased vessel injury and giant cells infiltration were late-acting contributors to neointimal hyperplasia (NIH). Stent type altered time-dependent process of vessel injury, vessel inflammation, eosinophils and giant cells infiltration. Misago had less fibrin deposition and vessel enlargement, and less progressive vessel injury, vessel inflammation, and eosinophils and giant cells infiltration. Net lumen as assessed by percent diameter stenosis or minimum lumen diameter was preserved with Misago, but was not preserved with the other stents.ConclusionsIn the context of bare nitinol SES platform with less progressive mechanical stress and inflammatory reaction, the advantage of less NIH outweighed the disadvantage of less vessel enlargement, leading to net lumen preservation.

The Percentage of PNAd-Expressing Vessels is Correlated with Disease Severity in Eosinophilic Chronic Rhinosinusitis.

Eosinophilic chronic rhinosinusitis (ECRS) is a chronic inflammatory condition of the paranasal sinuses characterized by intractable nasal polyps with prominent eosinophil infiltration. These eosinophils are presumably recruited from peripheral blood via vessels expressing peripheral lymph node addressin (PNAd), a set of glycoproteins decorated with 6-sulfo sialyl Lewis x (sLex) glycans that serve as L-selectin ligands. Based on the severity classification algorithm proposed by the Japanese Epidemiological Survey of Refractory Eosinophilic Chronic Rhinosinusitis (JESREC) study group, ECRS is divided into mild, moderate and severe groups; however, as yet there are few reports comparing the clinicopathological differences among these groups. Our goal was to elucidate clinicopathological differences among the three different severities of ECRS with special reference to eosinophils and PNAd-expressing vessels. We performed quantitative immunohistochemical analysis of PNAd-expressing vessels using surgical specimens of nasal polyps from patients exhibiting varying severity of ECRS (n = 35) and from individuals with non-ECRS (n = 10). To this end, we immunostained tissue sections with anti-PNAd and anti-CD34 monoclonal antibodies, and then determined the number of vessels immunolabeled with each antibody. The number of eosinophils infiltrating nasal polyps was correlated with ECRS severity. We also found that the PNAd + /CD34 + vessel ratio, namely, the percentage of PNAd-expressing vessels among all vessels, was positively correlated not only with ECRS severity but also with the number of eosinophils infiltrating nasal polyps formed in ECRS. These results strongly suggest that PNAd-expressing vessels play at least a partial role in eosinophil recruitment to nasal polyps and consequent severity of ECRS.

Intravascular Lithotripsy in Calcified Peripheral Lesions: Single-Center JEN-Experience.

Peripheral artery disease (PAD) shows increasing need for revascularization therapy. Interventional success in calcified lesions is limited. Here, intravascular lithotripsy (IVL), modifying intimal and medial calcium, is a promising treatment approach. A single-center, prospective all-comers registry for patients undergoing peripheral IVL was established to examine treatment success in PAD with severe vessel calcification. Periprocedural safety events as well as short-term and intermediate follow-up clinical data were evaluated. Between December 2018 and January 2021 all consecutive patients receiving peripheral lithotripsy at our center were analyzed. Clinical and angiographic data were evaluated. Angiographic images were analyzed using a semiautomatic software for quantitative vessel analysis. Eighty-five lesions in 61 limbs were treated with IVL in 51 patients presenting with Rutherford classes 2 to 5. Most lesions (68%) were localized in the superficial femoral artery. Mean calcified lesion length was 102.5 mm (10-390 mm), with a median peripheral arterial calcium score of 3, indicating a highly calcified status. In 58% of the patients, IVL was used as a stand-alone therapy. IVL resulted in a mean acute luminal gain of 2.6 ± 0.9 mm, resulting in stenosis reduction by 42.1 ± 15%. Mean ankle brachial index (ABI) improved significantly from 0.6 to 0.8 ( p < 0.0001) on day 1 after the intervention and remained stable at 6 months. This large real-world data of peripheral IVL reports compelling safety in a complex patient cohort. For the first time, clinical follow-up data demonstrated a sustained significant improvement in ABI after 6 months.

Blood Vessel Detection Algorithm for Tissue Engineering and Quantitative Histology

Immunohistochemistry for vascular network analysis plays a fundamental role in basic science, translational research and clinical practice. However, identifying vascularization in histological tissue images is time consuming and markedly depends on the operator’s experience. In this study, we present “blood vessel detection—BVD”, an automatic algorithm for quantitative analysis of blood vessels in immunohistochemical images. BVD is based on extraction and analysis of low-level image features and spatial filtering techniques, which do not require a training phase. BVD algorithm performance was comparatively evaluated on histological sections from three different in vivo experiments. Collectively, 173 independent images were analyzed, and the algorithm's results were compared to those obtained by human operators. The developed BVD algorithm proved to be a robust and versatile tool, being able to quantify number, area, and spatial distribution of blood vessels within all three considered histologic datasets. BVD is provided as an open-source application working on different operating systems. BVD is supported by a user-friendly graphical interface designed to facilitate large-scale analysis.

Accuracy of quantitative vessel analysis in endovascular treatment for femoropopliteal lesions.

Our aim was to evaluate the accuracy of quantitative vessel analysis (QVA) in measuring the reference vessel diameter (RVD) of femoropopliteal lesions. Between October 2014 and September 2015, 30 consecutive femoropopliteal lesions in 25 patients who underwent endovascular therapy (EVT) under intravascular ultrasound (IVUS) guidance were analyzed. RVDs measured using QVAsheath (calibrated using a 6-Fr sheath in the common femoral artery) and QVAruler (calibrated using a ruler on the angiography table) were compared to those obtained using IVUS as the reference values. The mean QVAsheath-measured RVD was significantly larger than the mean IVUS-measured RVD (5.34±1.29 vs. 5.07±1.20 mm, P=0.001). In contrast, mean QVAruler-measured RVD was 4.60±1.04 mm, which was significantly smaller than both the mean IVUS- and mean QVAsheath-measured RVD (both P<0.001). Bland-Altman analysis revealed that the 95% limits of agreement versus IVUS ranged from -0.94 to 1.49 mm for QVAsheath and -1.69 to 0.76 mm for QVAruler, respectively. Agreement with tolerance of ±1.00 mm accounted for 88% of QVAsheath and 83% of QVAruler (P=0.60). The difference between QVA- and IVUS-measured RVDs was inversely correlated with the distance from the table (P=0.029 for QVAsheath and P=0.003 for QVAruler). The accuracy of both QVAsheath and QVAruler in measuring RVD were similarly suboptimal. Over- and under-estimation of RVD is not rare in QVA.

Early Vascular and Functional Changes after Vitreoretinal Surgery: A Comparison between the Macular Hole and Epiretinal Membrane.

(1) Background: The aim of this observational comparative study was to investigate early retinal vascular and functional changes in patients undergoing vitreoretinal surgery for idiopathic epiretinal membrane (iERM) or macular hole (MH) using a widefield swept-source optical coherence tomography angiography (WSS-OCTA). (2) Methods: Forty one diseased eyes were enrolled in the study. Twenty three eyes with iERM diagnosis (ERM group) underwent 25-gauge vitrectomy with inner limiting membrane (ILM) and MER peeling, while eighteen eyes with MH (MH group) underwent 25-gauge vitrectomy with inverted flap technique. Functional and anatomical/perfusion parameters were evaluated pre- and postoperatively in all eyes by means of WSS-OCTA system, microperimetry (MP3), best corrected visual acuity assessment, central macular thickness (CMT) and MH diameter calculation. For each eye, 12 × 12 mm OCTA volume scans were acquired by a retinal specialist and a semi-automated algorithm was used for a quantitative vessel analysis of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris (CC). In detail, perfusion density (PD) of the SCP, DCP and CC was evaluated in four circles (one central in the macular area of 5 mm diameter; three midperiphery circles (temporal, superior and inferior) of 3 mm). In addition, the vessel length density (VLD) of the SCP and DCP for the same circles was quantified. (3) Results: In the MH group, PD of the SCP significantly increased in the macular area (p = 0.018) and in the superior ring (p = 0.016); PD of the DCP significantly increased in the macular area (p = 0.015) and in the superior and inferior ring (p = 0.016) 3 months after surgery. In the ERM group, PD of the SCP and DCP significantly increased in the macular area and superior ring, respectively (p = 0.001; p = 0.032), 3 months after surgery. During follow-up there was a significant improvement in terms of functional (Best corrected visual acuity, p = 0.007 and p = 0.029; microperimetry ((MP3) 10°, p = 0.003 and p = 0.004; MP3 2°, p = 0.028 and p = 0.003 in MH group and ERM group respectively) and anatomical parameters (CMT, p = 0.049 in ERM group; hole complete closure in MH group). (4) Conclusions: After vitreoretinal surgery, early retinal vascular and functional changes can be promptly observed and quantified to monitor and potentially predict surgery outcomes. Widefield OCTA devices allow for a detailed microvasculature analysis of retina and choriocapillaris in the macular area and in the periphery, showing a different behaviour of retinal sectors in two distinct vitreoretinal disorders.

Topology-Aware Retinal Artery–Vein Classification via Deep Vascular Connectivity Prediction

Retinal artery–vein (AV) classification is a prerequisite for quantitative analysis of retinal vessels, which provides a biomarker for neurologic, cardiac, and systemic diseases, as well as ocular diseases. Although convolutional neural networks have presented remarkable performance on AV classification, it often comes with a topological error, like an abrupt class flipping on the same vessel segment or a weakness for thin vessels due to their indistinct appearances. In this paper, we present a new method for AV classification where the underlying vessel topology is estimated to give consistent prediction along the actual vessel structure. We cast the vessel topology estimation as iterative vascular connectivity prediction, which is implemented as deep-learning-based pairwise classification. In consequence, a whole vessel graph is separated into sub-trees, and each of them is classified as an artery or vein in whole via a voting scheme. The effectiveness and efficiency of the proposed method is validated by conducting experiments on two retinal image datasets acquired using different imaging techniques called DRIVE and IOSTAR.

Combination of \xb5CT and light microscopy for generation-specific stereological analysis of pulmonary arterial branches: a proof-of-concept study

Various lung diseases, including pulmonary hypertension, chronic obstructive pulmonary disease or bronchopulmonary dysplasia, are associated with structural and architectural alterations of the pulmonary vasculature. The light microscopic (LM) analysis of the blood vessels is limited by the fact that it is impossible to identify which generation of the arterial tree an arterial profile within a LM microscopic section belongs to. Therefore, we established a workflow that allows for the generation-specific quantitative (stereological) analysis of pulmonary blood vessels. A whole left rabbit lung was fixed by vascular perfusion, embedded in glycol methacrylate and imaged by micro-computed tomography (µCT). The lung was then exhaustively sectioned and 20 consecutive sections were collected every 100 µm to obtain a systematic uniform random sample of the whole lung. The digital processing involved segmentation of the arterial tree, generation analysis, registration of LM sections with the µCT data as well as registration of the segmentation and the LM images. The present study demonstrates that it is feasible to identify arterial profiles according to their generation based on a generation-specific color code. Stereological analysis for the first three arterial generations of the monopodial branching of the vasculature included volume fraction, total volume, lumen-to-wall ratio and wall thickness for each arterial generation. In conclusion, the correlative image analysis of µCT and LM-based datasets is an innovative method to assess the pulmonary vasculature quantitatively.

Preliminary study on modelling, fabrication by photo-chemical etching and in vivo testing of biodegradable magnesium AZ31 stents

Magnesium metal (Mg) is a promising material for stent applications due to its biocompatibility and ability to be resorbed by the body. Manufacturing of stents by laser cutting has become an industry standard. Our alternative approach uses photo-chemical etching to transfer a pattern of the stent onto a Mg sheet. In this study, we present three stages of creating and validating a stent prototype, which includes design and simulation using finite element analysis (FEA), followed by fabrication based on AZ31 alloy and, finally, in vivo testing in peripheral arteries of domestic pigs. Due to the preliminary character of this study, only six stents were implanted in two domestic farm pigs weighing 25–28 kg and they were evaluated after 28 days, with an interim follow-up on day 14. The left and right superficial femoral, the left iliac, and the right renal artery were selected for this study. The diameters of the stented artery segments were evaluated at the time of implantation, on day 14 and then, finally, on day 28, by quantitative vessel analysis (QVA) using fluoroscopic imaging. Optical Coherence Tomography (OCT) imaging displayed some malposition, breaks, stacking, and protrusion into the lumen at the proximal, distal, and mid-sections of the stented arteries. The stents degraded with time, but simultaneously became embedded in the intima. After 28 days, the animals were euthanized, and explanted vessels were fixed for micro-CT imaging and histology studies. Micro-CT imaging revealed stent morphological and volumetric changes due to the in-body degradation. An in vivo corrosion rate of 0.75 mm/year was obtained by the CT evaluation. The histology suggested no-life threatening effects, although moderate injury, inflammation, and endothelialization scores were observed.

Full three-dimensional segmentation and quantification of tumor vessels for photoacoustic images

Quantitative analysis of tumor vessels is of great significance for tumor staging and diagnosis. Photoacoustic imaging (PAI) has been proven to be an effective way to visualize comprehensive tumor vascular networks in three-dimensional (3D) volume, while previous studies only quantified the vessels projected in one plane. In this study, tumor vessels were segmented and quantified in a full 3D framework. It had been verified in the phantom experiments that the 3D quantification results have better accuracy than 2D. Furthermore, in vivo vessel images were quantified by 2D and 3D quantification methods respectively. And the difference between these two results is significant. In this study, complete vessel segmentation and quantification method within a 3D framework was implemented, which showed obvious advantage in the analysis accuracy of 3D photoacoustic images, and potentially improve tumor study and diagnosis.

Lumen Loss at 1 Year After Bare Nitinol Stent Implantation in the Superficial Femoral Artery

Purpose To investigate lumen loss (LL) at 1 year after bare nitinol stent (BNS) implantation for de novo superficial femoral artery (SFA) lesions. Materials and Methods The subjects were 701 consecutive patients (mean age 74±9 years; 492 men) with 817 de novo SFA lesions treated with BNS implantation between January 2004 and September 2015. The mean lesion length was 141±88 mm and the mean vessel diameter was 5.4±0.9 mm. The endpoint was LL at 1 year after BNS implantation. Secondary outcomes were restenosis and target lesion revascularization (TLR) estimated using the Kaplan-Meier method; estimates are reported with the 95% confidence interval (CI). LL was defined as the minimum lumen diameter immediately after BNS implantation minus that at 1 year measured by angiographic quantitative vessel analysis. The distribution of LL in the overall population was estimated using an accelerated failure time model. Results Mean LL at 1 year was estimated to be 1.74±1.28 mm (95% CI 1.63 to 1.84). Current smoking was positively associated with LL (p=0.015), whereas lack of cilostazol use was correlated with an increase in LL (p=0.001). Reference vessel diameter and lesion length did not have any significant association with LL at 1 year. The 1-year cumulative estimate of restenosis was 25% (95% CI 22% to 28%); the corresponding value for TLR was 18% (95% CI 15% to 21%). Conclusion Mean LL progressed by at least 1.6 mm up to 1 year after BNS implantation. The risk factors for increased LL were current smoker and lack of cilostazol use.