Vessel Perfusion Research Articles

Hemodynamic analysis on the flow characteristics around abdominal aortic hemorrhage site

The hemodynamic characteristics of blood flow around the site of abdominal aortic hemorrhage can serve as a valuable indicator for identifying the location of hemorrhage. In this research, we conducted numerical simulations to analyze the flow fields in the patient-specific abdominal aorta with and without hemorrhage. We quantitatively compared differences in flow field patterns, blood loss, and branch vessel perfusion between hemorrhagic and non-hemorrhagic cases. Our numerical results demonstrate that there is a distinct hemodynamic characteristic observed around the hemorrhage site, characterized by continuous abnormal high-velocity (>0.7 m/s) and high-Rortex (>200) zone. Additionally, we evaluated the amount of blood loss and time to moderate shock for different cases of abdominal aortic hemorrhage, while statistically analyzing variations in branch vessel perfusion along the abdominal aorta. These findings provide quantitative estimations for blood loss, branch perfusion, and potential indicators to assess rescue time window as well as evaluate the extent of distal tissue damage and organ injury.

Effects of veno-arterial extracorporeal membrane oxygenation return cannula side hole structure on aortic hemodynamic features under different perfusion levels.

The interaction between primary left ventricular output and Veno-arterial extracorporeal membrane pulmonary oxygenation (VA ECMO) flow may impede the perfusion of aortic vessels with hyperoxic blood, leading to differential oxygenation. ECMO return cannula design significantly influences the perfusion level of blood supplied via ECMO. This study aimed to investigate the impact of various cannula designs (side hole number) on intravascular flow patterns under different blood perfusion conditions. Six return cannula models with different side hole number and three cardiac output waveforms were designed based on clinical data for comparative analysis. The position of the blood mixing zone (MZ) was influenced by the flow-volume ratio of the heart output (CO/(CO+Qec)) and cannula design. As the CO/(CO+Qec) and the number of side holes in the cannula increased, the MZ shifted from the ascending aorta to the descending aorta. Concurrently, aortic wall and scalar shear stress on the impact side of ECMO cannulation reduced progressively. Return cannula with side holes effectively mitigated discrepancies in the perfusion of the renal artery and inadequate perfusion of the lower limb vessels on the cannula side while simultaneously reducing damage to the vessel walls and blood. However, increasing the number of side holes in the return cannulas resulted in diminished perfusion of the aortic arch bifurcation vessels by hyperoxic blood supplied via ECMO. Increasing the number of return cannula side holes for VA ECMO femoral artery cannulation improves hypoxic perfusion in the lower limb and reduces vascular endothelial injury, but may also lead to inadequate hypoxic perfusion in the upper body.

Quantitative detection of macular microvascular abnormalities identified by optical coherence tomography angiography in different hematological diseases

It is now understood that hematological diseases can have detrimental effects on the retina, reducing retinal capillaries, compromising visual function, and potentially causing irreversible visual impairment. Over the years, there has been limited research on macular microvascular abnormalities, such as changes in vessel density and the foveal avascular zone (FAZ) and variations in the severity of these effects across different types of blood disorders. This study aims to quantitatively assess the impact of various hematological disorders on the retina using optical coherence tomography angiography (OCTA). Compared with healthy eyes, patients with different blood diseases exhibited reductions in linear vessel density (LVD), perfusion vessel density (PVD), FAZ area, and FAZ perimeter. Notably, patients with erythrocyte diseases showed more significant abnormalities in LVD and PVD, while patients with lymphocytic diseases demonstrated more pronounced abnormalities in the FAZ area and perimeter. OCTA imaging could potentially reflect changes of the retinal microvascular of patients with hematological diseases and may serve as a valuable tool for distinguishing abnormalities affecting different blood cell lines. This approach offers a novel avenue for assessing, treating, and monitoring blood disorders.

Neuroendoscopy Training

AbstractNeuroendoscopy can be learnt by assisting or doing live human surgery, cadaver dissection with or without augmented pulsatile vessel and cerebrospinal fluid (CSF) perfusion, and practicing on live animal, dead animal model, synthetic models, three-dimensional printing model with or without augmentation with animal, cadaver tissue, pulsatile vessel and reconstructed CSF model, virtual reality (VR) simulator, and hybrid simulators (combined physical model and VR model). Neurosurgery skill laboratory with basic and advanced learning should be there in all teaching hospitals. Skills can be transferred from simulation model or VR to cadaver to live surgery. Staged learning (first with simple model to learn basic endoscopic technique, then animal model, and then augmented cadavers) is the preferred method of learning. Although most surveys favor live surgery and practice on animal models and cadavers as the most preferred training model now, in future VR may also become a favored method of learning. This article is based on our experience in over 10,000 neuroendoscopic surgeries, and feedback from over 950 neuroendoscopic fellows or consultants who attended workshops conducted every 6 monthly since 2010. A literature search was done on PubMed and Google Scholar using (neuroendoscopy) AND (learning), and (neuroendoscopy) AND (training), which resulted in 121 and 213 results, respectively. Out of them, 77 articles were finally selected for this article. Most of the training programs typically focus on microneurosurgical training. There is lack of learning facilities for neuroendoscopy in most centers. Learning of neuroendoscopy differs greatly from microneurosurgery; switching from microneurosurgery to neuroendoscopy can be challenging. Postgraduate training centers should have well-equipped neuroendoscopy skill laboratory and the surgical educational curriculum should include neuroendoscopy training. Learning endoscopy is about taking advantages of the technique and overcoming the limitations of endoscopy by continuous training.

Losartan rewires the tumor-immune microenvironment and suppresses IGF-1 to overcome resistance to chemo-immunotherapy in ovarian cancer.

Ovarian cancer (OvCa) is the most lethal of the gynecologic malignancies. Immune checkpoint inhibitors, which have revolutionized the treatment of multiple malignancies, have had limited efficacy in OvCa patients. This lack of effectiveness is partly due to the abnormal ovarian tumor microenvironment (TME), displaying a desmoplastic, highly fibrotic extracellular matrix. High extracellular matrix deposition leads to a buildup of compressive forces that cause tumor blood vessel collapse, reduced vessel perfusion, poor delivery of drugs, and compromised trafficking of cytotoxic T-cells to these tumors. Using two syngeneic OvCa models, we tested the effect of losartan, a widely prescribed anti-hypertensive drug, on reprogramming the TME and chemosensitizing the cancer cells. Losartan treatment (i) reprograms the TME leading to increased vascular perfusion, and thus enhances drug delivery and immune effector cell intratumoral infiltration and function; and (ii) rewires the OvCa cells by suppressing the IGF-1 signaling, resulting in enhanced chemosensitivity. As a result of the combined tumor and stromal effects, losartan treatment enhances the efficacy of chemo-immunotherapy in OvCa models. The safety and low cost ( < $1-2/day) of losartan warrant rapid translation of our findings to patients with OvCa.

The generation of stable microvessels in ischemia is mediated by endothelial cell derived TRAIL.

Reversal of ischemia is mediated by neo-angiogenesis requiring endothelial cell (EC) and pericyte interactions to form stable microvascular networks. We describe an unrecognized role for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in potentiating neo-angiogenesis and vessel stabilization. We show that the endothelium is a major source of TRAIL in the healthy circulation compromised in peripheral artery disease (PAD). EC deletion of TRAIL in vivo or in vitro inhibited neo-angiogenesis, pericyte recruitment, and vessel stabilization, resulting in reduced lower-limb blood perfusion with ischemia. Activation of the TRAIL receptor (TRAIL-R) restored blood perfusion and stable blood vessel networks in mice. Proof-of-concept studies showed that Conatumumab, an agonistic TRAIL-R2 antibody, promoted vascular sprouts from explanted patient arteries. Single-cell RNA sequencing revealed heparin-binding EGF-like growth factor in mediating EC-pericyte communications dependent on TRAIL. These studies highlight unique TRAIL-dependent mechanisms mediating neo-angiogenesis and vessel stabilization and the potential of repurposing TRAIL-R2 agonists to stimulate stable and functional microvessel networks to treat ischemia in PAD.

Retinal microcirculation changes in prediabetic patients with short-term increased blood glucose using optical coherence tomography angiography.

Retinal microcirculation alterations are early indicators of diabetic microvascular complications. Optical coherence tomography angiography (OCTA) is a noninvasive method to assess these changes. This study analyzes changes in retinal microcirculation in prediabetic patients during short-term increases in blood glucose using OCTA. To investigate the changes in retinal microcirculation in prediabetic patients experiencing short-term increases in blood glucose levels using OCTA. Fifty volunteers were divided into three groups: Group 1 [impaired fasting glucose (IFG) or impaired glucose tolerance (IGT)], Group 2 (both IFG and IGT), and a control group. Retinal microcirculation parameters, including vessel density (VD), perfusion density (PD), and foveal avascular zone (FAZ) metrics, were measured using OCTA. Correlations between these parameters and blood glucose levels were analyzed in both the fasting and postprandial states. One hour after glucose intake, the central VD (P = 0.023), central PD (P = 0.026), and parafoveal PD (P < 0.001) were significantly greater in the control group than in the fasting group. In Group 1, parafoveal PD (P < 0.001) and FAZ circularity (P = 0.023) also increased one hour after glucose intake. However, no significant changes were observed in the retinal microcirculation parameters of Group 2 before or after glucose intake (P > 0.05). Compared with the control group, Group 1 had a larger FAZ area (P = 0.032) and perimeter (P = 0.018), whereas Group 2 had no significant differences in retinal microcirculation parameters compared with the control group (P > 0.05). Compared with Group 1, Group 2 had greater central VD (P = 0.013) and PD (P = 0.008) and a smaller FAZ area (P = 0.012) and perimeter (P = 0.010). One hour after glucose intake, Group 1 had a larger FAZ area (P = 0.044) and perimeter (P = 0.038) than did the control group, whereas Group 2 showed no significant differences in retinal microcirculation parameters compared with the control group (P > 0.05). Group 2 had greater central VD (P = 0.042) and PD (P = 0.022) and a smaller FAZ area (P = 0.015) and perimeter (P = 0.016) than Group 1. At fasting, central PD was significantly positively correlated with blood glucose levels (P = 0.044), whereas no significant correlations were found between blood glucose levels and OCTA parameters one hour after glucose intake. A short-term increase in blood glucose has a more pronounced effect on retinal microcirculation in prediabetic patients with either IFG or IGT.

Optical coherence tomography angiography analysis of the fellow eye in unilateral pseudoexfoliation syndrome

PurposeTo compare the macular and optic disc vascular parameters in the unaffected fellow eyes of subjects with unilateral pseudoexfoliation syndrome (PXS) and controls using optical coherence tomography angiography (OCTA).MethodsThe medical records of 61 eyes of 61 patients were analyzed in a retrospective study. Of these, 30 eyes were unaffected fellow eyes and 31 eyes were control eyes. The vessel density (VD), perfusion density (PD) and foveal avascular zone (FAZ)-related parameters of the superficial capillary plexus (SCP) in the circumpapillary and macular area and the VD and PD of the deep capillary plexus (DCP) in the macular area were measured using OCTA after dilatation and were compared between two groups after adjustment for age, sex and axial length.ResultsThere were no statistically significant differences in sex ratio or mean age, central corneal thickness measurements, refractive errors, intraocular pressures and axial length between both groups (all P > 0.05). In the circumpapillary area, inferior VD and PD in the inner zone, as well as average, temporal, inferior, and nasal VD and PD in the outer zone were significantly reduced in the unaffected fellow eyes with unilateral PXS, while the circumpapillary retinal nerve fiber layer (RNFL) thicknesses were similar between groups. In the macular SCP, VDs were significantly lower in all sectors in the inner area and in the outer zones (p < 0.05 for all), PDs were significantly lower in all sectors (p < 0.05 for all) except the nasal sector of the outer zone (p = 0.003 for average, p = 0.029 for superior sector, p = 0.004 for temporal sector, p < 0.001 for inferior sector), and the FAZ circularity (p = 0.037) were significantly lower in the unaffected fellow eyes with unilateral PXS, whereas macular ganglion cell inner plexiform layer (GCIPL) thickness was similar between the two groups.ConclusionsAlthough circumpapillary RNFL and GCIPL thicknesses were similar between the two groups, VDs and PDs in the circumpapillary and macular SCP and FAZ circularity were significantly lower in the fellow eye of subjects with unilateral PXS.

Cardio-ocular syndrome: Retinal microvascular changes in acutely decompensated heart failure.

To investigate the changes in retinal microvasculature by contemporary imaging techniques during episodes of acute decompensated heart failure (ADHF) and following recompensation compared to age-matched controls without known cardiac or retinal disease. Adult patients hospitalized with a primary diagnosis of ADHF, regardless of left ventricular ejection fraction (LVEF) and treated with a minimum dose of 40 mg of intravenous furosemide or equivalent were included. Transthoracic echocardiography was conducted in all patients. Eye examinations were performed out within the initial 24 h after admission and after recompensation before discharge. All eyes underwent a general examination, including a best corrected visual acuity test, dilated fundoscopy, spectral-domain optical coherence tomography (OCT) as well as OCT angiography (OCT-A). In addition, 40 participants without documented cardiac or retinal diseases served as controls. Forty patients with ADHF (mean age 78.9 ± 8.8 years; 32% female) with a mean LVEF of 43 ± 12.8% were included. All patients were treated with intravenous diuretics for a median of 4.3 ± 2.8 days. There was a significant reduction in N-terminal pro-B-type natriuretic peptide from baseline up to discharge (10 396 [interquartile range 6410] vs. 6380 [interquartile range 3933] pg/ml, p ≤ 0.001) and inferior vena cava diameters (2.13 ± 0.4 vs. 1.63 ± 0.3 cm, p = 0.003). Compared to the control group, patients with ADHF showed on admission impaired visual acuity (0.15 ± 0.1 vs. 0.35 ± 0.1 logMAR, p < 0.001), reduced macular vessel density (18.0 ± 1.9 vs. 14.3 ± 3.6 mm/mm2, p < 0.001) and perfusion density (42.6 ± 3.2 vs. 35.2 ± 9.7%, p < 0.001). After recompensation, the mean overall vessel density and mean overall perfusion density were markedly increased at discharge (14.3 ± 3.6 vs. 19.7 ± 2.6 mm/mm2, p = 0.001, and 35.2 ± 9.7 vs. 39.2 ± 6.5%, p = 0.005, respectively). The mean diameter of the superior temporal retinal vein at admission was significantly larger compared to the control group (136 ± 19 vs. 124 ± 22 μm, p = 0.008) and decreased significantly to 122 ± 15 μm at discharge (p < 0.001). This analysis revealed a remarkable reversible change in retinal microvasculature after ADHF. This could provide a valuable evidence for use of OCT-A in the assessment of overall microperfusion and haemodynamic status in patients with acute heart failure.

Perfusion deficit and vessel wall characteristics to predict recurrent ischemic events in medically treated patients with chronic symptomatic anterior circulation large vessel occlusion.

To investigate the association between perfusion deficit, vessel wall characteristics, and risk of recurrent ischemic events in medically treated patients with chronic symptomatic anterior circulation large vessel occlusion. We retrospectively reviewed chronic symptomatic patients due to anterior circulation large vessel occlusion in our center. All patients received multiparametric magnetic resonance imaging (including perfusion-weighted imaging and high-resolution vessel wall imaging) within 4 weeks to 3 months after symptom onset. The association between baseline clinical or imaging variables and recurrent ischemic events was assessed in bivariate models and multivariable logistic regression to identify independent predictors of recurrence. Among 71 enrolled patients, 21.1% (15/71) patients had recurrent ischemic events (nine ischemic strokes and six transient ischemic attacks) during a 2-year follow-up. In bivariate models, hypertension, occlusion with hyperintense signals, the presence of intraluminal thrombus, Tmax >4 s volume, Tmax >6 s volume, Tmax >8 s volume, and Tmax >10 s volume were associated with recurrence (all p < 0.05). In multivariate analysis, hypertension (p = 0.039, OR 10.057 (95% CI, 1.123-90.048)), higher deficit volume of Tmax >4 s (p = 0.011, OR 1.012 (95% CI, 1.003-1.021)) and occlusion with hyperintense signal (p = 0.030, OR 6.732 (95% CI, 1.200-37.772)) were still independent predictors of recurrent ischemic events. Besides hypertension history, higher deficit volume of Tmax >4 s and occlusion with hyperintense signal determined using multiparametric MRI are strongly associated with risk for recurrent ischemic events in medically treated patients with chronic symptomatic anterior circulation large vessel occlusion. Future studies are needed to determine the utility of revascularization strategies in such high-risk patients.

Non-invasive follow-up for intracranial aneurysms treated with contour neurovascular system-comparison of digital subtraction angiography (DSA) to magnetic resonance imaging (MRI) and spectral computed tomography angiography (CTA) in vitro.

The contour neurovascular system (CNS) is an intrasaccular flow-disrupting device designed for the treatment of intracranial wide-necked bifurcation aneurysms. Metal artifacts limit magnetic resonance imaging (MRI) accessibility after implantation. The purpose of this in vitro study was to evaluate non-invasive imaging alternatives to digital subtraction angiography (DSA). Three aneurysms of patients originally treated with CNS were three-dimensional (3D)-printed (one at the basilar tip and two at the middle cerebral artery bifurcation). CNS devices were implanted under fluoroscopic control into the 3D models. Post-implantation two-dimensional-DSA, flat panel computed tomography angiography (CTA), MRI, and spectral CTA were performed. Time of flight angiography and T1 weighted sequences showed large susceptibility artifacts at the detachment zone of the devices. A thin-sliced T2 weighted sequence in cross-sectional orientation to the aneurysm allowed visualization of the aneurysm dome, but the aneurysm neck and parent vessel could not be assessed. Focused spectral CTA, especially a 40 keV reconstruction with a metal artifact reduction algorithm (orthopedic metal artifact reduction (OMAR)), showed only minor artifacts at the detachment zone. This approach achieved a very similar result to DSA and flat panel computed tomography, enabling the assessment of the device structure, aneurysm perfusion, and parent vessel perfusion. For non-invasive follow-up of CNS, focused 40 keV CTA with OMAR seems to be a valuable option. MRI can be valuable for larger aneurysms to assess the aneurysm dome, but was not suitable for evaluating the parent vessels and aneurysm neck after CNS implantation in this study.

Prolonged inhibition of intratumoral mast cells enhances efficacy of low-dose antiangiogenic therapy.

Low-dose antiangiogenic therapies have demonstrated the ability to enhance normalization of tumor vessels, consequently improving hypoxia levels, drug delivery, and promoting anticancer immune responses. Mast cells have been identified as contributors to resistance against antiangiogenic therapy and facilitators of abnormal neoangiogenesis. In this study, we demonstrate that by simultaneously targeting intratumoral mast cells with Imatinib and administering low-dose anti-VEGFR2 therapy, antitumor efficacy can be enhanced in preclinical models. Thus, combinatory treatment overcomes therapy resistance, while concurrently promoting tumor vessel normalization. Notably, histomorphometric analysis of tumor sections revealed that vessel perfusion could be improved through mast cell inhibition and, despite a significantly reduced microvessel density, the combination treatment did not result in elevated tumor hypoxia levels compared to anti-VEGFR2 therapy alone. Short-term Imatinib application effectively increased antitumor efficacy, and by prolonging the application of Imatinib tumor vessel normalization was additionally improved. The combination of mast cell depletion and antiangiogenic treatments has not been investigated in detail and promises to help overcoming therapy resistance. Further studies will be required to explore their impact on other treatment approaches, and subsequently to validate these findings in a clinical setting.

Baseline tumour vessel perfusion as a non-invasive predictive biomarker for immune checkpoint therapy in non-small-cell lung cancer

ObjectiveCurrent biomarkers for predicting immunotherapy response in non-small-cell lung cancer (NSCLC) are derived from invasive procedures with limited predictive accuracy. Thus, identifying a non-invasive predictive biomarker would improve patient stratification...

Tumor-Derived Exosomes Promote Tumor Growth Through Modulating Microvascular Hemodynamics in a Human Ovarian Cancer Xenograft Model.

Abnormal tumor vascular network contributes to aberrant blood perfusion and reduced oxygenation in tumors, which lead to poor efficacy of chemotherapy and radiotherapy. We aimed to explore the effects of the tumor-derived exosomes (TDEs) and C188-9 (a small molecule inhibitor of signal transducer and activator of transcription 3, STAT3) on tumor microvascular hemodynamics and determine which blood flow oscillations for various frequency intervals are responsible for these changes. Microvascular hemodynamics parameters were recorded using a PeriFlux 6000 EPOS system in tumor surface in a nude mouse subcutaneous xenograft model. Oscillations of laser Doppler flowmetry (LDF) signal were investigated by wavelet transform analysis. TDEs facilitated tumor growth at least partially was associated with increasing blood flow in smaller vessels with lower speed and decreasing the blood flow at larger vessels with higher speed. Lower oxyhemoglobin saturation (SO2) on tumor surface was aggravated by TDEs, and C188-9 treatment significantly alleviated this decrease. Wavelet transform spectral analysis revealed that TDEs increased the amplitude of oscillations in four frequency intervals related to endothelial (NO-dependent and -independent), myogenic and neurogenic activities, and C188-9 had no effect on this increase. TDEs facilitated tumor growth partially was associated with increasing blood flow in distributing vessels, reducing blood perfusion in larger vessels, and lowering SO2 on tumor surface. Enhanced vascular smooth muscle, endothelial and neurogenic activities occurred in tumor superficial zone.

Effects of visual neuroplasticity training on visual perception, visual quality, and macular blood flow in patients with strabismus.

To observe the effects of visual neuroplasticity training on visual perception, visual quality, and macular blood flow in patients with concomitant strabismus postoperatively. In total, 108 patients underwent binocular strabismus correction operation, and some patients underwent neuroplasticity training. All patients underwent clinical ophthalmic examination, including measurement of best-corrected visual acuity, spherical equivalent, axis length, optical coherence tomography angiography, optical quality analysis system, and visual perception examinations. A total of 78 patients received neuroplasticity training for 1 month postoperatively, and 30 patients did not receive training. All patients underwent a visual perception examination preoperatively and at 1 day, 1 week, and 1 month postoperatively. Macular blood flow and visual quality were examined preoperatively and at 1 month postoperatively. Postoperative visual perception was better than preoperative visual perception (P < 0.05). After neuroplasticity training, the visual perception of the trained subjects was better than that of the untrained subjects (P < 0.05), and the blood flow in the macular area of the trained patients was lower than that of the untrained subjects (P < 0.05). The visual quality of the untrained subjects was lower than that of the trained patients (P < 0.05). Visual inspection system could accurately evaluate binocular visual perception in patients with concomitant strabismus. After surgical alignment of the strabismus patient, training can stimulate and integrate the formation of stereovision in a short period of time, maintain the visual quality of patients after surgery, and provide conditions for the formation of binocular visual signals and binocular stereovision, but in the short term, it will lead to the decrease of macular blood vessel density and perfusion density. However, the long-term effects of training have not been proven.

Polyvinylpyrrolidone-curcumin nanoparticles with immune regulatory and metabolism regulatory effects for the treatment of experimental autoimmune uveitis

Uveitis comprises a cluster of intraocular inflammatory disorders characterized by uncontrolled autoimmune responses and excessive oxidative stress leading to vision loss worldwide. In the present study, curcumin (CUR) was conjugated with polyvinylpyrrolidone (PVP) to form PVP-CUR nanoparticles with significantly elevated solubility and outstanding multiple radical scavenging abilities. In vitro studies revealed that PVP-CUR nanoparticles markedly mitigated oxidative stress and reduced apoptosis in a H2O2-induced human retinal pigment epithelial cell line (ARPE-19) and promoted phenotypic polarization from M1 to M2 in an LPS-induced human microglial cell line (HMC3). Further in vivo studies demonstrated the prominent therapeutic effects of PVP-CUR nanoparticles on experimental autoimmune uveitis (EAU), which relieved clinical and pathological progression, improved perfusion and tomographic manifestations of retinal vessels, and reduced blood–retinal barrier (BRB) leakage; these effects may be mediated by mitigating oxidative stress and attenuating macrophage/microglia-elicited inflammation. Notably, treatment with PVP-CUR nanoparticles was shown to regulate metabolite alterations in EAU rats, providing novel insights into the underlying mechanisms involved. Additionally, the PVP-CUR nanoparticles showed great biocompatibility in vivo. In summary, our study revealed that PVP-CUR nanoparticles may serve as effective and safe nanodrugs for treating uveitis and other oxidative stress- and inflammation-related diseases.

Role of Vitreous Detachment in Epiretinal Membrane Peeling: A Multimodal Imaging and Microperimetry Study.

Background: To investigate anatomical and functional changes of the macula caused by epiretinal membrane (ERM) peeling procedures in patients with or without posterior vitreous detachment (PVD). Methods: This is a multicentric prospective observational study on thirty-seven (37) patients affected by symptomatic ERM who underwent 25-gauge pars plana vitrectomy (PPV), induction of a PVD (as needed) and peeling of both the internal limiting membrane (ILM) and ERM. Optical coherence tomography-angiography (OCT-A) (RS 3000, Nidek, Japan) and microperimetry (MP-3, Nidek, Japan) were performed; central retinal thickness (CRT), foveal avascular zone (FAZ) area and perimeter, vessel density and perfusion density, retinal sensitivity and fixation stability (as a total mean retinal sensitivity (MRS), and MRS in the ellipse area and bivariate contour ellipse area (BCEA)) were recorded at baseline and up to postoperative month 3. Results: Eyes were classified as having complete PVD (51.4%) or incomplete PVD (48.6%). At baseline, patients with incomplete PVD had worse best-corrected distance visual acuity (BCDVA), total MRS, MRS in the ellipse area and BCEA, and higher CRT than patients with complete PVD. At month 3, the differences in BCDVA between the two groups remained statistically significant, with patients with incomplete PVD having worse results (difference: 0.199 logMAR, p < 0.001). The difference in the MRS in the ellipse area was statistically significant at month 3 (-3.378 Db, p = 0.035), with greater improvement in patients with complete PVD. Conclusions: Our study shows that patients with incomplete PVD have worse conditions at baseline than patients with complete PVD, and the differences in visual acuity and retinal sensitivity were maintained postoperatively.

Advances in Vascular Diagnostics using Magnetic Particle Imaging (MPI) for Blood Circulation Assessment.

Rapid and accurate assessment of conditions characterized by altered blood flow, cardiac blood pooling, or internal bleeding is crucial for diagnosing and treating various clinical conditions. While widely used imaging modalities such as magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound offer unique diagnostic advantages, they fall short for specific indications due to limited penetration depth and prolonged acquisition times. Magnetic particle imaging (MPI), an emerging tracer-based technique, holds promise for blood circulation assessments, potentially overcoming existing limitations with reduction in background signals and high temporal and spatial resolution, below the millimeter scale. Successful imaging of blood pooling and impaired flow necessitates tracers with diverse circulation half-lives optimized for MPI signal generation. Recent MPI tracers show potential in imaging cardiovascular complications, vascular perforations, ischemia, and stroke. The impressive temporal resolution and penetration depth also position MPI as an excellent modality for real-time vessel perfusion imaging via functional MPI (fMPI). This review summarizes advancements in optimized MPI tracers for imaging blood circulation and analyzes the current state of pre-clinical applications. This work discusses perspectives on standardization required to transition MPI from a research endeavor to clinical implementation and explore additional clinical indications that may benefit from the unique capabilities of MPI.

The usefulness of super-selective arterial spin labeling for postoperative evaluation of pediatric moyamoya disease: technical note

Moyamoya disease is characterized by progressive internal carotid artery (ICA) occlusion. Extracranial-intracranial bypass surgery is effective, particularly in pediatric patients; imaging plays a crucial role in evaluating intracranial perfusion pre- and post-surgery. Arterial spin labeling (ASL) is a magnetic resonance technique employed for noninvasive, whole-brain perfusion assessment by magnetically labeling inflowing blood. However, ASL cannot evaluate the territories and development of each vessel perfusion compared with digital subtraction angiography (DSA). Recently, super-selective ASL (SS-ASL) has been developed, performing pinpoint labeling on a specific artery at a time, and offering a tomographic view that distinctly displays blood supply areas for each vessel. Unlike DSA, SS-ASL is noninvasive and can be repeatedly performed in pediatric patients. In conclusion, SS-ASL is useful for evaluating bypass development over time and understanding the pathophysiology of pediatric moyamoya disease.

Patterns of Progression of Nonproliferative Diabetic Retinopathy Using Non-Invasive Imaging.

To identify progression of nonproliferative diabetic retinopathy (NPDR) in patients with type 2 diabetes by combining optical coherence tomography angiography (OCTA) metrics and color fundus photography (CFP) images. This study was a post hoc analysis of a prospective longitudinal cohort study (CORDIS, NCT03696810) with 2-year duration. This study enrolled 122 eyes. Ophthalmological examinations included OCTA and CFP. OCTA metrics included skeletonized vessel density (SVD) and perfusion density (PD) at the superficial capillary plexus (SCP) and deep capillary plexus (DCP). Microaneurysm turnover analysis and Early Treatment Diabetic Retinopathy Study (ETDRS) grading for diabetic retinopathy (DR) severity assessment were performed on 7-field CFP. Eyes graded as ETDRS level 20 showed significant capillary nonperfusion predominantly in the inner ring area in the SCP (P < 0.001), whereas eyes graded as ETDRS level 35 and ETDRS levels 43 and 47 showed significant capillary nonperfusion in both the SCP and DCP in both inner and outer rings (P < 0.001). When evaluating rates of progression in capillary nonperfusion for the 2-year period of follow-up, changes were found predominantly in the DCP for SVD and PD and were better identified in the outer ring area. Microaneurysm turnover contributes to the characterization of NPDR progression by discriminating ETDRS level 35 from ETDRS levels 43 and 47 (P < 0.001), which could not be achieved using only OCTA metrics. Patterns of progression of NPDR can be identified combining OCTA examinations of the superficial and deep retinal capillary plexi of central retina and determination of microaneurysm turnover from fundus photographs. Our study reports results from a registered clinical trial that advances understanding of disease progression in NPDR.