Multimodality imaging of lower extremity peripheral arterial disease: current role and future directions

Musculoskeletal manifestations of COVID-19

During the COVID-19 pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected millions of people worldwide, with acute respiratory distress syndrome (ARDS) being the most common severe condition of pulmonary involvement. Despite its involvement in the lungs, SARS-CoV-2 causes multiple extrapulmonary manifestations, including manifestations in the musculoskeletal system. Several cases involving bone, joint, muscle, neurovascular and soft tissues were reported shortly after pandemic onset. Even after the acute infection has resolved, many patients experience persistent symptoms and a decrease in quality of life, a condition known as post-COVID syndrome or long COVID. COVID-19 vaccines have been widely available since December 2020, preventing millions of deaths during the pandemic. However, adverse reactions, including those involving the musculoskeletal system, have been reported in the literature. Therefore, the primary goal of this article is to review the main imaging findings of SARS-CoV-2 involvement in the musculoskeletal system, including acute, subacute, chronic and postvaccination manifestations.

Cost-effectiveness of diagnostic imaging modalities in symptomatic patients with lower limb peripheral arterial disease: discrete event simulation model

Objective

Lower limb peripheral arterial disease in the symptomatic stage has a significant effect on patients´ functional disability. Before an intervention, an imaging diagnostic examination is necessary to determine the extent of the disability. This study evaluates cost-effectiveness of duplex ultrasonography (DUS), digital subtraction angiography (DSA), computed tomography angiography (CTA) and magnetic resonance angiography (MRA) in the diagnostics of symptomatic patients with lower limb peripheral arterial disease indicated for endovascular or surgical intervention.

Methods

Discrete event simulation was used to capture lifetime costs and effects. Costs were calculated from the perspective of the health care payer, and the effects were calculated as quality-adjusted life year's (QALY's). The cost-effectiveness analysis was performed to pairwise compare CTA, MRA and DSA with DUS as the baseline diagnostic modality. A scenario analysis and probabilistic sensitivity analysis were carried out to evaluate the robustness of the results.

Results

In the basic case, the DUS diagnostic was the least expensive modality, at a cost of EUR 10,778, compared with EUR 10,804 for CTA, EUR 11,184 for MRA, and EUR 11,460 for DSA. The effects of DUS were estimated at 5.542 QALYs compared with 5.554 QALYs for both CTA and MRA, and 5.562 QALYs for DSA. The final incremental cost-effectiveness ratio (ICER) value of all evaluated modalities was below the cost-effectiveness threshold whereas CTA has the lowest ICER of EUR 2,167 per QALY. However, the results were associated with a large degree of uncertainty, because iterations were spread across all cost-effectiveness quadrants in the probabilistic sensitivity analysis.

Conclusion

For imaging diagnosis of symptomatic patients with lower limb peripheral arterial disease, CTA examination appears to be the most cost-effective strategy with the best ICER value. Baseline diagnostics of the DUS modality has the lowest costs, but also the lowest effects. DSA achieves the highest QALYs, but it is associated with the highest costs.

Leveraging the Cardiovascular Team in Peripheral Artery Disease Diagnosis: A Call to Action

Lower extremity peripheral artery disease (PAD) is a common atherosclerotic cardiovascular disease (ASCVD) involving the aortoiliac, femoropopliteal, and infrapopliteal arterial segments. PAD remains a largely underdiagnosed and undertreated condition. The ankle-brachial index (ABI) is a simple and widely available test that is key detection tool in the diagnosis of PAD and is prognostic for mortality and morbidity. The cardiovascular (CV) team is a diverse array of health care clinicians (eg, nurses, nurse practitioners, physician assistants/associates, pharmacists, podiatrists) who have the qualifications and skills to be able to recognize when patients are at risk for PAD and perform an ABI. It is critical that the healthcare community recognize the critical role the CV team could play in improving outcomes and reducing disparities for patients with PAD.

Design and development of the DE-SPECT system: a clinical SPECT system for broadband multi-isotope imaging of peripheral vascular disease

Objective. Peripheral Vascular Disease (PVD) affects more than 230 million people worldwide and is one of the leading causes of disability among people over age 60. Nowadays, PVD remains largely underdiagnosed and undertreated, and requires the development of tailored diagnostic approaches. We present the full design of the Dynamic Extremity SPECT (DE-SPECT) system, the first organ-dedicated SPECT system for lower extremity imaging, based on 1 cm thick Cadmium Zinc Telluride (CZT) spectrometers and a dynamic dual field-of-view (FOV) synthetic compound-eye (SCE) collimator.Approach. The proposed DE-SPECT detection system consists of 48 1 cm thick 3D-position-sensitive CZT spectrometers arranged in a partial ring of 59 cm in diameter in a checkerboard pattern. The detection system is coupled with a compact dynamic SCE collimator that allows the user to select between two different FOVs at any time during an imaging study: a wide-FOV (28 cm diameter) configuration for dual-leg or scout imaging or a high-resolution and high-sensitivity (HR-HS) FOV (16 cm diameter) for single-leg or focused imaging.Main results.The preliminary experimental data show that the CZT spectrometer achieves a 3D intrinsic spatial resolution of <0.75 mm FWHM and an excellent energy resolution over a broad energy range (2.6 keV FWHM at 218, 3.3 keV at 440 keV). From simulations, the wide-FOV configuration offers a 0.034% averaged sensitivity at 140 keV and <8 mm spatial resolution, whereas the HR-HS configuration presents a peak central sensitivity of 0.07% at 140 keV and a ∼5 mm spatial resolution. The dynamic SCE collimator enables the capability to perform joint reconstructions that would ensure an overall improvement in imaging performance.Significance. The DE-SPECT system is a stationary and high-performance SPECT system that offers an excellent spectroscopic performance with a unique computer-controlled dual-FOV imaging capability, and a relatively high sensitivity for multi-tracer and multi-functional SPECT imaging of the extremities.

Clinical physiology: the crucial role of MRI in evaluation of peripheral artery disease

Peripheral artery disease (PAD) is a common vascular disease that primarily affects the lower limbs and is defined by the constriction or blockage of peripheral arteries and may involve microvascular dysfunction and tissue injury. Patients with diabetes have more prominent disease of microcirculation and develop peripheral neuropathy, autonomic dysfunction, and medial vascular calcification. Early and accurate diagnosis of PAD and disease characterization are essential for personalized management and therapy planning. Magnetic resonance imaging (MRI) provides excellent soft tissue contrast and multiplanar imaging capabilities and is useful as a noninvasive imaging tool in the comprehensive physiological assessment of PAD. This review provides an overview of the current state of the art of MRI in the evaluation and characterization of PAD, including an analysis of the many applicable MR imaging techniques, describing the advantages and disadvantages of each approach. We also present recent developments, future clinical applications, and future MRI directions in assessing PAD. The development of new MR imaging technologies and applications in preclinical models with translation to clinical research holds considerable potential for improving the understanding of the pathophysiology of PAD and clinical applications for improving diagnostic precision, risk stratification, and treatment outcomes in patients with PAD.

Multi-Modality Imaging of Atheromatous Plaques in Peripheral Arterial Disease: Integrating Molecular and Imaging Markers

Peripheral artery disease (PAD) is a common and debilitating condition characterized by the narrowing of the limb arteries, primarily due to atherosclerosis. Non-invasive multi-modality imaging approaches using computed tomography (CT), magnetic resonance imaging (MRI), and nuclear imaging have emerged as valuable tools for assessing PAD atheromatous plaques and vessel walls. This review provides an overview of these different imaging techniques, their advantages, limitations, and recent advancements. In addition, this review highlights the importance of molecular markers, including those related to inflammation, endothelial dysfunction, and oxidative stress, in PAD pathophysiology. The potential of integrating molecular and imaging markers for an improved understanding of PAD is also discussed. Despite the promise of this integrative approach, there remain several challenges, including technical limitations in imaging modalities and the need for novel molecular marker discovery and validation. Addressing these challenges and embracing future directions in the field will be essential for maximizing the potential of molecular and imaging markers for improving PAD patient outcomes.

Can Sublingual Nitrate Improve Visualization of Lower Limb Arteries on Computed Tomography Angiography?

OBJECTIVE

The aim of the study is to evaluate the role of sublingual nitrate in improving vessel visualization on peripheral computed tomography angiography (CTA).

METHODS

Fifty patients clinically diagnosed with peripheral arterial disease of the lower limb were prospectively included in this study: Twenty-five underwent CTA after sublingual nitrate administration (nitrate group) and 25 without (non-nitrate group). Two blinded observers qualitatively and quantitatively assessed the data thus generated. The mean luminal diameter, intraluminal attenuation, site, and percentage of stenosis were evaluated in all segments. Assessment of collateral visualization at sites of significant stenosis was also done.

RESULTS

Patients in the nitrate and non-nitrate groups were similar in age and sex characteristics (P > 0.05).On subjective evaluation, there was significantly improved visualization of the femoropopliteal and tibioperoneal vasculature of the lower limb in the nitrate group compared with the non-nitrate group (P < 0.05). Quantitative evaluation showed a statistically significant difference in the measured arterial diameters for all evaluated segments in the nitrate group versus the non-nitrate group (P < 0.05). Intra-arterial attenuation was significantly greater for all segments in the nitrate group resulting in better contrast opacification in these studies. Collateral visualization around segments with more than 50% stenosis/occlusion was also better in the nitrate group.

CONCLUSIONS

Our study suggests that nitrate administration before peripheral vascular CTA can improve visualization, especially in the distal segments by increasing the vessel diameter and intraluminal attenuation along with better delineation of the collateral circulation around stenotic areas. It may also improve the number of evaluable segments of vasculature in these angiographic studies.

Automatic force-controlled 3D photoacoustic system for human peripheral vascular imaging

Photoacoustic (PA) imaging provides unique advantages in peripheral vascular imaging due to its high sensitivity to hemoglobin. Nevertheless, limitations associated with handheld or mechanical scanning by stepping motor techniques have precluded photoacoustic vascular imaging from advancing to clinical applications. As clinical applications require flexibility, affordability, and portability of imaging equipment, current photoacoustic imaging systems developed for clinical applications usually use dry coupling. However, it inevitably induces uncontrolled contact force between the probe and the skin. Through 2D and 3D experiments, this study proved that contact forces during the scanning could significantly affect the vascular shape, size, and contrast in PA images, due to the morphology and perfusion alterations of the peripheral blood vessels. However, there is no available PA system that can control forces accurately. This study presented an automatic force-controlled 3D PA imaging system based on a six-degree-of-freedom collaborative robot and a six-dimensional force sensor. It is the first PA system that achieves real-time automatic force monitoring and control. This paper's results, for the first time, demonstrated the ability of an automatic force-controlled system to acquire reliable 3D PA images of peripheral blood vessels. This study provides a powerful tool that will advance PA peripheral vascular imaging to clinical applications in the future.

Advanced virtual monoenergetic imaging algorithm for lower extremity computed tomography angiography: effects on image quality, artifacts, and peripheral arterial disease evaluation

PURPOSE

To investigate the image quality of lower extremity computed tomography angiography (LE-CTA) using a reconstruction algorithm for monoenergetic images (MEIs) to evaluate peripheral arterial disease (PAD) at different kiloelectron volt (keV) levels.

METHODS

A total of 146 consecutive patients who underwent LE-CTA on a dual-energy scanner to obtain MEIs at 40, 50, 60, 70, and 80 keV were included. The overall image quality, segmental image quality of the arteries and PAD segments, venous contamination, and metal artifacts from prostheses, which may compromise quality, were analyzed.

RESULTS

The mean overall image quality of each MEI was 2.9 ± 0.7, 3.6 ± 0.6, 3.9 ± 0.3, 4.0 ± 0.2, and 4.0 ± 0.2 from 40 to 80 keV, respectively. The segmental image quality gradually increased from 40 to 70-80 keV until reaching its highest value. Among 295 PAD segments in 68 patients, 40 (13.6%) were scored at 1-2 at 40 keV and 13 (4.4%) were scored at 2 at 50 keV, indicating unsatisfactory image quality due to the indistinguishability between high-contrast areas and arterial calcifications. The segments exhibiting metal artifacts and venous contamination were reduced at 70-80 keV (2.6 ± 1.2, 2.7 ± 0.5) compared with at 40 keV (2.4 ± 1.1, 2.5 ± 0.7).

CONCLUSION

The LE-CTA method using a reconstruction algorithm for MEIs at 70-80 keV can enhance the image quality for PAD evaluation and improve mitigate venous contamination and metal artifacts.

Postintervention monitoring of peripheral arterial disease wound healing using dynamic vascular optical spectroscopy

SIGNIFICANCE

Due to the persistence of chronic wounds, a second surgical intervention is often necessary for patients with peripheral arterial disease (PAD) within a year of the first intervention. The dynamic vascular optical spectroscopy system (DVOS) may assist physicians in determining patient prognosis only a month after the first surgical intervention.

AIM

We aim to assess the DVOS utility in characterizing wound healing in PAD patients after endovascular intervention.

APPROACH

The DVOS used near-infrared light ( 670 < λ < 850    nm ) to record hemodynamic response to a cuff inflation in 14 PAD patients with lower limb ulcers immediately before, immediately after, and at a first follow-up 3 to 4 weeks after intervention. Ankle-brachial index (ABI) and arterial duplex ultrasound (A-DUS) measurements were obtained when possible.

RESULTS

The total hemoglobin plateau time differed significantly between patients with ulcers that reduced in size ( N = 9 ) and patients with ulcers that did not ( N = 5 ) 3 to 4 weeks after intervention ( p  value < 0.001 ). Data correlated strongly (89% sensitivity, 100% specificity, and AUC = 0.96 ) with long-term wound healing. ABI and A-DUS measurements were not statistically associated with wound healing.

CONCLUSIONS

This pilot study demonstrates the potential of the DVOS to aid physicians in giving accurate long-term wound healing prognoses 1 month after intervention.

Discrete Event Simulation Model for Cost-Effectiveness Evaluation of Screening for Asymptomatic Patients with Lower Extremity Arterial Disease

Lower limb ischemic disease (LEAD) affects a significant portion of the population, with most patients being asymptomatic. Patient screening is necessary because LEAD patients have an increased risk of occurrence of other cardiovascular events and manifestations of disease, in terms of leg symptoms such as intermittent claudication, critical limb ischemia, or amputation. The aim of this work was to evaluate the cost-effectiveness of screening using ABI diagnostics in asymptomatic patients and its impact on limb symptoms associated with LEAD. A discrete event simulation model was created to capture lifetime costs and effects. Costs were calculated from the perspective of the health care payer, and the effects were calculated as QALYs. A cost-effectiveness analysis was performed to compare ABI screening examination and the situation without such screening. A probabilistic sensitivity analysis and scenario analysis were carried out to evaluate the robustness of the results. In the basic setting, the screening intervention was a more expensive intervention, at a cost of CZK 174,010, compared to CZK 70,177 for the strategy without screening. The benefits of screening were estimated at 14.73 QALYs, with 14.46 QALYs without screening. The final ICER value of CZK 389,738 per QALY is below the willingness to pay threshold. Likewise, the results of the probabilistic sensitivity analysis and of the scenario analysis were below the threshold of willingness to pay, thus confirming the robustness of the results. In conclusion, ABI screening appears to be a cost-effective strategy for asymptomatic patients aged 50 years when compared to the no-screening option.

Imaging Findings of Peripheral Arterial Disease on Lower-Extremity CT Angiography Using a Virtual Monoenergetic Imaging Algorithm

Peripheral arterial disease (PAD) is common in elderly patients. Lower-extremity CT angiography (LE-CTA) can be useful for detecting PAD and planning its treatment. PAD can also be accurately evaluated on reconstructed monoenergetic images (MEIs) from low kiloelectron volt (keV) to high keV images using dual-energy CT. Low keV images generally provide higher contrast than high keV images but also feature more severe image noise. The noise-reduced virtual MEI reconstruction algorithm, called the Mono+ technique, was recently introduced to overcome such image noise. Therefore, this pictorial review aimed to present the imaging findings of PAD on LE-CTA and compare low and high keV images with those subjected to the Mono+ technique. We found that, in many cases, the overall and segmental image qualities were better and metal artifacts and venous contamination were decreased in the high keV images.

Emergent Magnetic Resonance Angiography for Evaluation of the Thoracoabdominal and Peripheral Vasculature

Thoracoabdominal and peripheral vasculature pathologies include a variety of severe and life threatening conditions that may be encountered in the emergent setting. Computed tomography angiography (CTA) is the first-line modality for imaging of the vasculature in this context, but magnetic resonance angiography (MRA) also plays an important and emerging role in the evaluation of carefully selected patients. Intravenous (IV) iodinated contrast is necessary for CTA, although MRA is most useful in patients who cannot receive IV iodinated contrast for reasons including prior severe allergic-like reaction to iodinated contrast, poor IV access, or severe renal insufficiency. Gadolinium-based contrast agents are administered for MRA when possible, as they generally improve the diagnostic quality and shorten the duration of the exam. In most clinical situations, however, noncontrast MRA is sufficient to obtain a diagnostic evaluation. In this review, we discuss the key strengths and limitations of MRA performed in the emergent setting, highlighting the role of MRA in the diagnosis of acute aortic syndromes, aortitis, aortic aneurysm, pulmonary embolism, and peripheral vascular disease.

Influence of diabetes on diagnostic performance of computed tomography angiography of the calf arteries in acute limb ischemia

BACKGROUND

Patients with diabetes mellitus (DM) have a more extensive distal arterial occlusive disease compared to non-diabetic patients. Diagnostic imaging is a necessity to identify the location and extent of the arterial occlusion in acute limb ischemia (ALI). Computed tomography angiography (CTA) is the most commonly used modality and the diagnostic performance with CTA of calf arteries may be questioned.

PURPOSE

To evaluate diagnostic performance of CTA of calf arteries in ALI and to compare patients with and without DM.

MATERIAL AND METHODS

All thrombolytic treatments performed during 2001-2018 in patients with ALI were included. Initial digital subtraction angiography (DSA) and CTA of all patients were classified according to the Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II) below-the-knee arteries and compared to CTA. Two raters assessed the CTA images independently. Inter-rater reliability was expressed as intraclass correlation (ICC) with 95% confidence intervals (CI).

RESULTS

Patients with (n = 23) and without (n = 85) DM had lower (P = 0.006) glomerular filtration rate. ICC between CTA and DSA was 0.33 (95% CI -0.22 to 0.56) and 0.71 (95% CI 0.38-0.68) in patients with and without DM, respectively. Sensitivity with CTA for TASC D lesions in patients with and without DM was 0.14 (95% CI -0.12 to 0.40) and 0.64 (95% CI 0.48-0.80), respectively.

CONCLUSION

The sensitivity of CTA for assessment of infra-popliteal TASC D lesions in patients with ALI was not acceptable in patients with DM in contrast to those without DM. Another imaging option at present times should be considered for patients with DM.

Dedicated Photoacoustic Imaging Instrument for Human Periphery Blood Vessels: A New Paradigm for Understanding the Vascular Health

A novel photoacoustic imaging system based on a semi-ring transducer array is proposed to image peripheral blood vessels. The system's penetration depth is deep (∼15 mm) with high spatial (∼200 μm) and temporal resolution. In a clinical study, volumetric photoacoustic data of limbs were obtained within the 50s (for a FOV of 15 cm × 4 cm) with the volunteers in the standing and sitting posture. Compared to the previous studies, our system has many advantages, including (1) Larger field of view; (2) Finer elevational and in-plane resolutions; (3) Enhanced 3D visualization of peripheral vascular networks; (4) Compact size and better portability. The 3D visualization and cross-sectional images of five healthy volunteers clearly show the vascular network and the system's ability to image submillimeter blood vessels. This high-resolution PA system has great potential for imaging human periphery vasculatures noninvasively in clinical research.

Dual Function of a in vivo Albumin-Labeling Tracer for Assessment of Blood Perfusion and Vascular Permeability in Peripheral Arterial Disease by PET

Background

Peripheral arterial disease (PAD) leads to tissue ischemia in the extremities. Enhanced vascular permeability plays a critical role in targeted delivery of drugs for effective therapeutic angiogenesis and resultant blood perfusion recovery. However, optimal tracers for evaluating this process in PAD patients are lacking. At this time, we employed a novel in vivo albumin-labeling tracer of dual function, termed as ¹⁸F-NEB, to assess blood perfusion as well as vascular permeability by positron emission tomography (PET).

Methods and Results

After successful establishment of mouse hindlimb ischemia (HI) model, static PET imaging was performed 15 min and 2 h post injection (p.i.) of ¹⁸F-NEB at 1, 3, 5, 7, 10 and 14 days post-surgery respectively. Gradual recovery of blood supply was detected by PET scan 15 min p.i. and collaborated by serial Laser Doppler. In addition, the highest vascular permeability observed by high local uptake of ¹⁸F-NEB at 2 h p.i. was consistent with histological examinations. Furthermore, we quantitatively evaluated the effect of vascular endothelial growth factor (VEGF) stimulus on vascular permeability and blood perfusion by PET scan using ¹⁸F-NEB probe in HI model, which were also confirmed by immunohistological results.

Conclusion

The application of ¹⁸F-NEB probe alone by PET can successfully achieve dual imaging of blood perfusion as well as vascular permeability at different time points p.i. and monitor their responses to therapy in PAD model. The simple labeling approach and multipurpose feature suggest the great promise of using this imaging probe in theranostic applications for treating ischemic disease.

Peripheral Artery Disease: A comprehensive updated review

Peripheral arterial disease is estimated to affect more than 200 million people worldwide. Although more than 50% of those affected are asymptomatic, it accounts for 3-4% of amputations and a crude five-year death rate of 82.4 deaths per 1000 patient-years when adjusted for duration of follow-up. Additionally, peripheral artery disease is often an indicator of obstructive atherosclerotic disease involvement of cerebral and coronary vessels, consequently increasing the risk of stroke, cardiovascular death, and myocardial infarction in these patient populations. The management of peripheral arterial disease includes conservative therapies, pharmacological treatments, interventional and surgical revascularization of blood vessels. Percutaneous transluminal angioplasty with balloons and stents has improved clinical outcomes compared to medical treatment alone. Despite these advances, the prevalence of peripheral arterial disease remains high. This review article aims to provide focused, up-to-date information on the clinical course, diagnosis, medical and interventional approach of the management of peripheral artery disease.

Automatic segmentation of peripheral arteries and veins in ferumoxytol-enhanced MR angiography

PURPOSE

To automate the segmentation of the peripheral arteries and veins in the lower extremities based on ferumoxytol-enhanced MR angiography (FE-MRA).

METHODS

Our automated pipeline has 2 sequential stages. In the first stage, we used a 3D U-Net with local attention gates, which was trained based on a combination of the Focal Tversky loss with region mutual loss under a deep supervision mechanism to segment the vasculature from the high-resolution FE-MRA datasets. In the second stage, we used time-resolved images to separate the arteries from the veins. Because the ultimate segmentation quality of the arteries and veins relies on the performance of the first stage, we thoroughly evaluated the different aspects of the segmentation network and compared its performance in blood vessel segmentation with currently accepted state-of-the-art networks, including Volumetric-Net, DeepVesselNet-FCN, and Uception.

RESULTS

We achieved a competitive F1 = 0.8087 and recall = 0.8410 for blood vessel segmentation compared with F1 = (0.7604, 0.7573, 0.7651) and recall = (0.7791, 0.7570, 0.7774) obtained with Volumetric-Net, DeepVesselNet-FCN, and Uception. For the artery and vein separation stage, we achieved F1 = (0.8274/0.7863) in the calf region, which is the most challenging region in peripheral arteries and veins segmentation.

CONCLUSION

Our pipeline is capable of fully automatic vessel segmentation based on FE-MRA without need for human interaction in <4 min. This method improves upon manual segmentation by radiologists, which routinely takes several hours.

Quiescent-Interval Slice-Selective MRA Accurately Estimates Intravascular Stent Dimensions Prior to Intervention in Patients With Peripheral Artery Disease

BACKGROUND

Quiescent-interval slice-selective (QISS) magnetic resonance angiography (MRA) is a non-contrast alternative for the pre-procedural assessment of patients with peripheral artery disease (PAD). However, the feasibility of pre-procedural stent size estimation using QISS MRA would merit investigation.

PURPOSE

To evaluate the feasibility of QISS MRA for pre-procedural stent size estimation in PAD patients compared to computed tomography angiography (CTA).

STUDY TYPE

Retrospective.

SUBJECTS

Thirty-three PAD patients (68 ± 9 years, 18 men, 15 women).

FIELD STRENGTH/SEQUENCE

Two-dimensional balanced steady-state free precession QISS MRA at 1.5 T and 3 T.

ASSESSMENT

All patients received QISS MRA and CTA of the lower extremity run-off followed by interventional digital subtraction angiography (DSA). Stenotic lesion length and diameter were quantified (AMF and AVS with 3 and 13 years of experience in cardiovascular imaging, respectively) to estimate the dimensions of the stent necessary to restore blood flow in the treated arteries. Measured dimensions were adjusted to the closest stent size available.

STATISTICAL TESTS

The Friedman test with subsequent pairwise Wilcoxon signed-rank test was used to compare the estimated stent dimensions between QISS MRA, CTA, and the physical stent size used for intervention. Intra-class correlation (ICC) analysis was performed to assess inter-reader agreement. Significant differences were considered at P < 0.05.

RESULTS

No significant difference was observed between estimated stent diameter by QISS MRA or CTA compared to physical stent diameter (8.9 ± 2.9 mm, 8.8 ± 3.0 mm, and 8.8 ± 3.8 mm, respectively; χ²  = 1.45, P = 0.483). There was a significant underestimation of stent length for both QISS MRA and CTA, compared to physical stent length (45.8 ± 27.8 mm, 46.4 ± 29.3 mm, and 50.4 ± 34.0 mm, respectively; χ²  = 11.96) which could be corrected when measurements were adjusted to the next available stent length (χ²  = 2.38, P = 0.303). Inter-reader assessment showed good to excellent agreement between the readers (all ICC ≥0.81).

DATA CONCLUSION

QISS MRA represents a reliable method for pre-procedural lesion assessment and stent diameter and length estimation in PAD patients.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Evaluation of foot hypoperfusion and estimation of percutaneous transluminal angioplasty outcome in patients with critical limb ischemia using intravoxel incoherent motion microperfusion MRI

OBJECTIVES

To emerge hypoperfusion of lower limbs in patients with critical limb ischemia (CLI) using Intravoxel Incoherent Motion microperfusion magnetic resonance imaging (IVIM-MRI). Moreover to examine the ability of IVIM-MRI to differentiate patients with severe peripheral arterial disease (PAD) from normal subjects and evaluate the percutaneous transluminal angioplasty (PTA) results in patients with CLI.

METHODS

Eight patients who presented with CLI and six healthy volunteers were examined. The patients underwent IVIM-MRI of lower extremity before and following PTA. The imaging protocol included sagittal diffusion-weighted (DW) sequences. DW images were analyzed and color parametric maps of the micro-circulation of blood inside the capillary network (D*) were constructed. The studies were evaluated by two observers to define interobserver reproducibility.

RESULTS

Technical success was achieved in all patients (8/8). The mean ankle-brachial index increased from 0.35 ± 0.2 to 0.76 ± 0.25 (p < 0.05). Successful revascularization improved IVIM microperfusion. Mean D* increased from 279.88 ± 13.47 10^-5 mm²/s to 331.51 ± 31 10^-5 mm²/s, following PTA, p < 0.05. Moreover, PAD patients presented lower D* values as compared to healthy individuals (279.88 ± 13.47 10^-5 mm²/s vs 332.47 ± 22.95 10^-5 mm²/s, p < 0.05, respectively). Good interobserver agreement was obtained with an ICC = 0.84 (95% CI 0.64-0.93).

CONCLUSIONS

IVIM-MRI can detect differences in microperfusion between patients with PAD and healthy individuals. Moreover, significant restitution of IVIM microperfusion is found following successful PTA.

ADVANCES IN KNOWLEDGE

IVIM-MRI is a safe, reproducible and effective modality for evaluation of lower limb hypoperfusion in patients with PAD. It seems also to be a helpful tool to detect changes of tissue perfusion in patients with CLI following revascularization.

Lower extremity CT angiography in peripheral arterial disease: from the established approach to evolving technical developments

With the advent of multidetector computed tomography (CT), CT angiography (CTA) has gained widespread popularity for noninvasive imaging of the arterial vasculature. Peripheral extremity CTA can nowadays be performed rapidly with high spatial resolution and a decreased amount of both intravenous contrast and radiation exposure. In patients with peripheral artery disease (PAD), this technique can be used to delineate the bilateral lower extremity arterial tree and to determine the amount of atherosclerotic disease while differentiating between acute and chronic changes. This article provides an overview of several imaging techniques for PAD, specifically discusses the use of peripheral extremity CTA in patients with PAD, clinical indications, established technical considerations and novel technical developments, and the effect of postprocessing imaging techniques and structured reporting.

Variability in utilization of diagnostic imaging tests in patients with symptomatic peripheral artery disease

AIM

Imaging can help guide management in peripheral arterial disease (PAD) with symptoms refractory to medical treatment. However, there are no set guidelines to determine when physicians should seek further imaging in patients with PAD for the assessment of new, persistent or worsening symptoms. This study describes the rates and variability in non-invasive and invasive imaging for patients presenting to vascular specialty clinics for symptomatic PAD.

METHODS

Patients (n=1,275) with a new PAD diagnosis or exacerbation of PAD symptoms were enrolled from 16 vascular clinics. Hierarchical logistic regression models were used to estimate the referral rates for 1) non-invasive and 2) invasive imaging tests, after adjusting for patient demographics, disease characteristics, PAQ summary score, PAD performance measures and country. Median Odds Ratios (MOR) were calculated to examine the variability across sites and providers.

RESULTS

Mean ABI was 0.67 ± 0.19. There were 690 (54.1%) patients who had imaging, of which 62 (9.0%) had invasive imaging. Imaging rates ranged from 8.6% to 98.6% across sites. The MOR for use of imaging for site was 3.36 (p < 0.001) and provider 3.49 (p < 0.001). The variability was explained primarily by (R² = 29%) country followed by patient-level factors, provider and lastly site (R² = 17%, 14%, and 13%, respectively).

CONCLUSION

There is wide variation in the use of imaging for patients presenting with new onset or recent exacerbations of their PAD. Country, followed by provider and site, were most strongly associated with this variability after adjusting for patient characteristics.

Photoacoustic Imaging of Human Vasculature Using LED versus Laser Illumination: A Comparison Study on Tissue Phantoms and In Vivo Humans

Vascular diseases are becoming an epidemic with an increasing aging population and increases in obesity and type II diabetes. Point-of-care (POC) diagnosis and monitoring of vascular diseases is an unmet medical need. Photoacoustic imaging (PAI) provides label-free multiparametric information of deep vasculature based on strong absorption of light photons by hemoglobin molecules. However, conventional PAI systems use bulky nanosecond lasers which hinders POC applications. Recently, light-emitting diodes (LEDs) have emerged as cost-effective and portable optical sources for the PAI of living subjects. However, state-of-art LED arrays carry significantly lower optical energy (<0.5 mJ/pulse) and high pulse repetition frequencies (PRFs) (4 KHz) compared to the high-power laser sources (100 mJ/pulse) with low PRFs of 10 Hz. Given these tradeoffs between portability, cost, optical energy and frame rate, this work systematically studies the deep tissue PAI performance of LED and laser illuminations to help select a suitable source for a given biomedical application. To draw a fair comparison, we developed a fiberoptic array that delivers laser illumination similar to the LED array and uses the same ultrasound transducer and data acquisition platform for PAI with these two illuminations. Several controlled studies on tissue phantoms demonstrated that portable LED arrays with high frame averaging show higher signal-to-noise ratios (SNRs) of up to 30 mm depth, and the high-energy laser source was found to be more effective for imaging depths greater than 30 mm at similar frame rates. Label-free in vivo imaging of human hand vasculature studies further confirmed that the vascular contrast from LED-PAI is similar to laser-PAI for up to 2 cm depths. Therefore, LED-PAI systems have strong potential to be a mobile health care technology for diagnosing vascular diseases such as peripheral arterial disease and stroke in POC and resource poor settings.

Quick evaluation of lower leg ischemia in patients with peripheral arterial disease by time maximum intensity projection CT angiography: a pilot study

Background

The purpose of this study is to evaluate a new method involving time maximum intensity projection (t-MIP) postprocessed from dynamic computed tomographic angiography (dyn-CTA) in diagnosing peripheral arterial disease (PAD).

Methods

A population of 34 patients with known PAD was examined with a combined CTA protocol consisting of a standard CTA (s-CTA) scan of the lower extremities and a dyn-CTA scan of the calves. For each lower leg, t-MIP images consisting of the MIP₀ (sagittal MIP), MIP_+θ (45° lateral MIP), and MIP_−θ (− 45° lateral MIP) were automatically generated from dyn-CTA. An objective evaluation of the vascular CT attenuation of the best enhancement phase of dyn-CTA and t-MIP was measured; a subjective evaluation of vessel stenosis and occlusion was performed, assigning a score for t-MIP and s-CTA. The CT attenuation of t-MIP and dyn-CTA was compared, as were the runoff scores of t-MIP and s-CTA.

Results

The CT attenuation of t-MIP CTA of three vascular segments from 68 lower extremities was higher than that of the best enhancement phase of dyn-CTA and s-CTA, with statistically significant differences at the posterior tibial artery and fibular artery (all p < 0.05). There were strong correlations (r ≥ 0.75, p < 0.05) of the runoff scores between t-MIP and s-CTA.

Conclusions

There is potential clinical applicability of t-MIP in assisting with the diagnosis of lower leg vascular stenosis in dyn-CTA with reliable diagnostic accuracy and convenient immediacy.

Multispectral optoacoustic tomography of peripheral arterial disease based on muscle hemoglobin gradients-a pilot clinical study

BACKGROUND

Current imaging assessment of peripheral artery disease (PAD) relies on anatomical cross-sectional visualizations of the affected arteries. Multispectral optoacoustic tomography (MSOT) is a novel molecular imaging technique that provides direct and label-free visualizations of soft tissue perfusion and oxygenation.

METHODS

MSOT was prospectively assessed in a pilot trial in healthy volunteers (group n1=4, mean age 31, 50% male and group n3=4, mean age 37.3, 75% male) and patients with intermittent claudication (group n2=4, mean age 72, 75% male, PAD stage IIb). We conducted cuff-induced ischemia (group n1) and resting state measurements (groups n2 and n3) over the calf region. Spatially resolved mapping of oxygenated (HbO2), deoxygenated (Hb) and total (THb) hemoglobin, as well as oxygen saturation (SO2), were measured via hand-held hybrid MSOT-Ultrasound based purely on hemoglobin contrast.

RESULTS

Calf measurements in healthy volunteers revealed distinct dynamics for HbO2, Hb, THb and SO2 under cuff-induced ischemia. HbO2, THb and SO2 levels were significantly impaired in PAD patients compared to healthy volunteers (P<0.05 for all parameters). Revascularization led to significant improvements in HbO2 of the affected limb.

CONCLUSIONS

Clinical MSOT allows for non-invasive, label-free and real-time imaging of muscle oxygenation in health and disease with implications for diagnostics and therapy assessment in PAD.

Multimodality imaging beyond CLEM: Showcases of combined in-vivo preclinical imaging and ex-vivo microscopy to detect murine mural vascular lesions

In imaging, penetration depth comes at the expense of lateral resolution, which restricts the scope of 3D in-vivo imaging of small animals at micrometer resolution. Bioimaging will need to expand beyond correlative light and electron microscopy (CLEM) approaches to combine insights about in-vivo dynamics in a physiologically relevant 3D environment with ex-vivo information at micrometer resolution (or beyond) within the spatial, structural and biochemical contexts. Our report demonstrates the immense potential for biomedical discovery and diagnosis made available by bridging preclinical in-vivo imaging with ex-vivo biological microscopy to zoom in from the whole organism to individual structures and by adding localized spectroscopic information to structural and functional information. We showcase the use of two novel imaging pipelines to zoom into mural lesions (occlusions/hyperplasia and micro-calcifications) in murine vasculature in a truly correlative manner, that is using exactly the same animal for all integrated imaging modalities. This correlated multimodality imaging (CMI) approach includes well-established technologies such as Positron Emission Tomography (microPET), Autoradiography, Magnetic Resonance Imaging (microMRI) and Computed Tomography (microCT), and imaging approaches that are more novel in the biomedical setting, such as X-Ray Fluorescence Spectroscopy (microXRF) and High Resolution Episcopic Microscopy (HREM). Although the current pipelines are focused on mural lesions, they would also be beneficial in preclinical and clinical investigations of vascular diseases in general.

Molecular and Cellular Mechanisms of Electronegative Lipoproteins in Cardiovascular Diseases

Dysregulation of glucose and lipid metabolism increases plasma levels of lipoproteins and triglycerides, resulting in vascular endothelial damage. Remarkably, the oxidation of lipid and lipoprotein particles generates electronegative lipoproteins that mediate cellular deterioration of atherosclerosis. In this review, we examined the core of atherosclerotic plaque, which is enriched by byproducts of lipid metabolism and lipoproteins, such as oxidized low-density lipoproteins (oxLDL) and electronegative subfraction of LDL (LDL(−)). We also summarized the chemical properties, receptors, and molecular mechanisms of LDL(−). In combination with other well-known markers of inflammation, namely metabolic diseases, we concluded that LDL(−) can be used as a novel prognostic tool for these lipid disorders. In addition, through understanding the underlying pathophysiological molecular routes for endothelial dysfunction and inflammation, we may reassess current therapeutics and might gain a new direction to treat atherosclerotic cardiovascular diseases, mainly targeting LDL(−) clearance.

Non-contrast-enhanced MR-angiography (MRA) of lower extremity peripheral arterial disease at 3 tesla: Examination time and diagnostic performance of 2D quiescent-interval single-shot MRA vs. 3D fast spin-Echo MRA

PURPOSE

Non-contrast enhanced MRA is a promising diagnostic alternative to contrast-enhanced (CE-) MRA or CT in patients with lower extremity peripheral arterial disease (PAD) but potentially associated with prolonged examination times and inferior diagnostic performance. We aimed to compare examination times and diagnostic performance of non-contrast enhanced quiescent-interval slice-selective (QISS)-MRA and fast-spin-echo (FSE)-MRA at 3.0 T.

MATERIALS AND METHODS

Forty-five patients with PAD were recruited for this IRB approved prospective study. Subjects underwent lower extremity MRA with 1) QISS-MRA, 2) FSE-MRA, and 3) CE-MRA (continuous table movement MRA and time-resolved MRA of the calf), which served as the standard of reference. Scan times for each examination step and total examination times for each of the three techniques was determined. Image quality and degree of stenosis were rated by two readers on a 5-point Likert scale. Sensitivity, specificity and diagnostic accuracy for relevant (>50%) stenosis were calculated.

RESULTS

Median total examination time was 27:02 min for QISS-MRA (IQR, 25:13-31:01 min), 28:37 min for FSE-MRA (IQR, 25:51-33:12 min), and 31:22 min for CE-MRA (IQR, 26:41-33:23 min). Acquisition time for QISS-MRA was significantly longer compared to FSE-MRA and CE-MRA (p ≤ 0.0001), while time for localizers, scouts and planning of the MRA sequence was significantly shorter for QISS-MRA compared to FSE-MRA and CE-MRA (p ≤ 0.0001). QISS-MRA had significantly better image quality compared to FSE-MRA with less segments classified as non-diagnostic (Reader 1: 3% vs. 35%; Reader 2: 3% vs. 50%, p ≤ 0.0001). Overall, QISS-MRA showed significantly better diagnostic performance than FSE-MRA (sensitivity, 85% vs. 54%; specificity, 90% vs. 47%, diagnostic accuracy, 89% vs. 48%; p ≤ 0.0001).

CONCLUSION

Total examination time of QISS-MRA and FSE-MRA was comparable with a conventional CE-MRA protocol. QISS-MRA showed significantly higher diagnostic performance than FSE-MRA.

Diagnostic accuracy of non-contrast quiescent-interval slice-selective (QISS) MRA combined with MRI-based vascular calcification visualization for the assessment of arterial stenosis in patients with lower extremity peripheral artery disease

OBJECTIVES

The proton density-weighted, in-phase stack-of-stars (PDIP-SOS) MRI technique provides calcification visualization in peripheral artery disease (PAD). This study sought to investigate the diagnostic accuracy of a combined non-contrast quiescent-interval slice-selective (QISS) MRA and PDIP-SOS MRI protocol for the detection of PAD, in comparison with CTA and digital subtraction angiography (DSA).

METHODS

Twenty-six prospectively enrolled PAD patients (70 ± 8 years) underwent lower extremity CTA and 1.5-T or 3-T PDIP-SOS/QISS MRI prior to DSA. Two readers rated image quality and graded stenosis (≥ 50%) on QISS MRA without/with calcification visualization. Sensitivity, specificity, and area under the curve (AUC) were calculated against DSA. Calcification was quantified and compared between MRI and non-contrast CT (NCCT) using paired t test, Pearson's correlation, and Bland-Altman analysis.

RESULTS

Image quality ratings were significantly higher for CTA compared to those for MRA (4.0 [3.0-4.0] and 3.0 [3.0-4.0]; p = 0.0369). The sensitivity and specificity of QISS MRA, QISS MRA with PDIP-SOS, and CTA for ≥ 50% stenosis detection were 85.4%, 92.2%, and 90.2%, and 90.3%, 93.2%, and 94.2%, respectively, while AUCs were 0.879, 0.928, and 0.923, respectively. A significant increase in AUC was observed when PDIP-SOS was added to the MRA protocol (p = 0.0266). Quantification of calcification showed significant differences between PDIP-SOS and NCCT (80.6 ± 31.2 mm³ vs. 88.0 ± 29.8 mm³; p = 0.0002) with high correlation (r = 0.77, p < 0.0001) and moderate mean of differences (- 7.4 mm³).

CONCLUSION

QISS MRA combined with PDIP-SOS MRI provides improved, CTA equivalent, accuracy for the detection of PAD, although its image quality remains inferior to CTA.

KEY POINTS

• Agreement in stenosis detection rate using non-contrast quiescent-interval slice-selective MRA compared to DSA improved when calcification visualization was provided to the readers. • An increase was observed in both sensitivity and specificity for the detection of ≥ 50% stenosis when MRI-based calcification assessment was added to the protocol, resulting in a diagnostic accuracy more comparable to CTA. • Quantification of calcification showed statistical difference between MRI and non-contrast CT; however, a high correlation was observed between the techniques.

Evaluation of Hemodynamics in a Murine Hindlimb Ischemia Model Using Spatial Frequency Domain Imaging

BACKGROUND AND OBJECTIVES

Spatial frequency domain imaging (SFDI), an optical imaging technique capable of quantitatively measuring tissue hemodynamics over a large field-of-view, has captured the interest of scientists and clinicians due to its ability to image rapidly and noninvasively. The goal of this study was to apply SFDI in a preclinical murine model to assess its ability to measure hemodynamic changes due to hindlimb ischemia in vivo longitudinally.

STUDY DESIGN/MATERIALS AND METHODS

Complete unilateral femoral artery ligation was performed on a total of nine C57BL/6J mice to induce ischemia in the left hindlimb. Changes in vascular perfusion in each mouse were monitored through SFDI acquisition of both the ischemic and control limbs throughout the course of 4 weeks. High-frequency pulsed-wave Doppler ultrasound was also acquired to confirm occlusion of the left femoral artery post-ligation compared with the control limb, while histological analysis was used to quantify femoral artery lumen shape and size.

RESULTS

Tissue oxygen saturation in the ischemic limb normalized to the control limb decreased from a ratio of 0.96 ± 0.06 at baseline to 0.86 ± 0.10 at day 1, then 0.94 ± 0.06 at day 3, followed by 0.95 ± 0.14 at day 7, 0.91 ± 0.09 at day 14, 0.90 ± 0.09 at day 21, and 1.01 ± 0.09 at day 28.

CONCLUSION

The results of this study indicate the utility of SFDI to detect hemodynamic changes in a preclinical murine model, as well as how to effectively use this tool to extract information regarding ischemia-induced hindlimb changes. In our model, we observed a decline in tissue oxygen saturation within one day post-ischemic injury, followed by a return to baseline values over the 4-week study period. While reducing skin artifacts and modifying camera hardware could still improve this murine imaging approach, our multimodality study presented here suggests that SFDI can be used to reliably characterize ischemia-mediated changes in a clinically relevant mouse model of peripheral arterial disease. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

"Push-button" noncontrast MR angiography using balanced T1 relaxation-enhanced steady-state (bT1RESS)

PURPOSE

We introduce a MR imaging technique, balanced T₁ relaxation-enhanced steady-state (bT1RESS), that provides the unique capability to efficiently impart a flexible amount of T₁ weighting to a balanced steady-state free precession acquisition using periodically applied contrast-modifying RF pulses. Leveraging this capability to suppress the signal intensity of background tissues, we implemented a 3D noncontrast MR angiography technique that continuously acquires thin overlapping 3D volumes and tested it for evaluation of the peripheral arteries.

METHODS

bT1RESS used a fast interrupted steady-state readout with a 45° cslab-selective ontrast-modifying RF pulse applied at 262 msec intervals. A series of 16.4-mm thick overlapping 3D volumes was acquired using a radial stack-of-stars k-space trajectory. The combination of slice oversampling, slab overlap, and averaging of edge slices was helpful to reduce venetian blind artifact. Spatial resolution was near isotropic with reconstructed slice thickness = 0.7 mm and in-plane resolution = 0.5 mm.

RESULTS

Pilot studies in the peripheral arteries demonstrated improved vessel sharpness compared with cardiac-gated quiescent interval slice-selective noncontrast MR angiography. bT1RESS noncontrast MR angiography reliably identified stenotic and occlusive arterial disease in a small cohort of patients with peripheral artery disease.

CONCLUSIONS

bT1RESS provides the basis for a simplified, completely "push button" approach for noncontrast MR angiography that obviates the need for contrast agents, electrocardiographic gating, scout imaging, breath holding, or tailoring of imaging parameters for the individual patient. Further work is needed for technical optimization and clinical validation.

Treatment of iliac atherosclerotic lesions using the balloon-expandable dynamic bare metal stent: One-year outcomes of the BIODYNAMIC single-center retrospective analysis

OBJECTIVES

Endovascular therapy using balloon expandable stents has become the treatment standard for most iliac atherosclerotic lesions. We aimed to assess the safety and performance of the Dynamic stainless-steel balloon-expanding stent system in this location.

METHODS

BIODYNAMIC is a retrospective single center study including consecutive patients with iliac lesions treated with the Dynamic stent system. Not included were implantations inside an endograft. The primary endpoint was freedom from major adverse limb events (MALE) at 12 months, defined as index limb amputation or target lesion revascularization (TLR). Secondary endpoints were procedure success, ankle brachial index (ABI) and Rutherford class change, mortality and freedom from TLR after 12 months.

RESULTS

Within two years, 182 patients with 234 lesions in the common iliac artery were enrolled. Rutherford class 5 and 6 were present in 11.5% of patients, average stent diameter was 8.0 ± 0.5 mm and stented length 40.0 ± 15.3 mm. The primary endpoint was reached in 96.2% (225/234) of the cases, with six TLR (2.6%) and three target limb amputations (1.3%). Procedure success was obtained in all but three patients (98.4%). In paired analysis, ABI improved by 0.25 ± 0.21 from baseline to 0.90 ± 0.16 post-procedure and Rutherford class improved by -1.75 ± 1.53. There were four non-device-related deaths (2.2%). Freedom from TLR was 97%, 95.3%, 94% and 92.7% at 24, 36, 48 and 60 months, respectively.

CONCLUSION

The Dynamic balloon-expandable stent system proved to be safe and effective in a population with common iliac artery lesions.

Diagnosis and Management of Peripheral Artery Diseases

Распространенность заболеваний периферических артерий (ЗПА) во всем мире достигает порядка 200 миллионов человек. Самым частым клиническим проявлением ЗПА является перемежающая хромота, возникающая вследствие недостаточного кровоснабжения пораженной конечности. В настоящем обзоре литературы обобщены и систематизированы последние достижения в области диагностики и лечения пациентов с перемежающей хромотой. Тщательный сбор анамнеза и физикальное обследование являются первоочередными мероприятиями для установления предварительного диагноза и направлены на дифференциацию сосудистых и нейрогенных причин перемежающей хромоты. Лодыжечно-плечевой индекс относится к наиболее часто используемым методам скрининга и диагностики ЗПА. Основу лечения составляют четыре взаимодополняющих подхода: немедикаментозное и лекарственное лечение для купирования симптомов хронической ишемии, фармакотерапия для вторичной профилактики сердечно-сосудистых осложнений, открытая или эндоваскулярная реваскуляризация для увеличения дистанции безболевой ходьбы. Недавнее исследование COMPASS продемонстрировало преимущества комбинированного применения 2,5 мг ривароксабана дважды в день и аспирина в части снижения уровня неблагоприятных сердечно-сосудистых событий, при этом отмечался более высокий риск геморрагических осложнений. На сегодняшний день цилостазол является единственным препаратом, обладающим доказанной терапевтической эффективностью в отношении перемежающей хромоты. Программы лечебной физкультуры под наблюдением врача либо в домашних условиях способствуют улучшению коллатерального кровообращения и увеличивают дистанцию ходьбы без боли. Назначение высоких доз статинов и антитромбоцитарных препаратов абсолютно обосновано всем пациентам с ЗПА. Ингибиторы ангиотензин-превращающего фермента обеспечивают дополнительное снижение кардиоваскулярных рисков, в особенности у пациентов с сахарным диабетом и артериальной гипертензией.

The prevalence of peripheral artery disease (PAD) worldwide reaches about 200 million people. The most frequent clinical manifestation of PAD is intermittent claudication, which occurs due to insufficient blood supply to the affected limb. This literature review summarizes and systematizes recent advances in the diagnosis and treatment of patients with intermittent claudication.Thorough case history collection and physical examination are the primary measures for making a preliminary diagnosis, which is aimed at differentiating the vascular and neurogenic causes of intermittent claudication. The ankle-shoulder index is one of the most commonly used methods for screening and diagnosing PAD. The basis of treatment consists of four complementary approaches: non-pharmacological and pharmacological treatment for the relief of symptoms of chronic ischemia, pharmacotherapy for the secondary prevention of cardiovascular complications, open or endovascular revascularization to increase the distance of pain-free walking. A recent COMPASS study demonstrated the benefits of combining 2.5 mg of rivaroxaban twice daily with aspirin in reducing adverse cardiovascular events, however there was a higher risk of hemorrhagic complications. Today, cilostazol is the only drug with proven therapeutic effectiveness against intermittent claudication. Physical therapy programs under the supervision of a doctor or at home help to improve collateral blood circulation and increase the walking distance without pain. The administration of high doses of statins and antiplatelet drugs is absolutely justified in all patients with PAD. Angiotensin converting enzyme inhibitors provide an additional reduction in cardiovascular risks, especially in patients with diabetes and hypertension.

Novel diagnostic and imaging techniques in endovascular iliac artery procedures

INTRODUCTION

Endovascular revascularization has become the preferred treatment for most patients with iliac artery obstructions, with a high rate of clinical and technical success.

AREAS COVERED

This review will describe novel developments in the diagnosis and treatment of iliac artery obstructions including the augmentation of preprocedural imaging with advanced flow models, image fusion techniques, and state-of-the-art device-tracking capabilities.

EXPERT OPINION

The combination of these developments will change the endovascular field within the next 5 years, allowing targeted iliac treatment without the need for radiographic imaging or iodinated contrast media.

The role of dynamic contrast-enhanced MRI in evaluation of percutaneous transluminal angioplasty outcome in patients with critical limb ischemia

PURPOSE

Imaging modalities such as CTA and MRA provide significant information about the distribution of macrovascular lesions of the limbs in patients with peripheral arterial disease but not for the local microvascular perfusion of the feet. The purpose of this study is to evaluate foot perfusion in patients with critical limb ischemia (CLI) and estimate percutaneous transluminal angioplasty (PTA) results, using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

METHODS

Ten patients (6 male, median age 68 years) with CLI were examined. All patients underwent DCE-MRI of the lower limb before and within first month after PTA. Perfusion parameters such as blood flow (BF), Ktrans, Kep were analyzed and applied for statistical comparisons. The studies were also examined by a second observer to determine inter-observer reproducibility.

RESULTS

Revascularization was technically successful in all patients and mean ankle brachial index (ABI) increased from 0.37 ± 0.18 to 0.76 ± 0.23, p < 0.05. After PTA, mean BF increased from 6.232 ± 2.867-9.867 ± 2.965 mL/min/100 g, K^trans increased from 0.060 ± 0.022 to 0.107 ± 0.041 min^-1 and K_ep increased from 0.103 ± 0.024 to 0.148 ± 0.024 min^-1, p < 0.05. All measurements demonstrated very good inter-observer reliability with an ICC > 0.85 for all perfusion parameters.

CONCLUSIONS

DCE-MRI is a safe and reproducible modality for the diagnosis of foot hypo-perfusion. It seems also to be a promising tool for evaluation of PTA outcome, as significant restitution of perfusion parameters was observed after successful revascularization.

A Quantitative Method for Prediction of True Lumen Recanalization in Chronic Total Occlusion of the Superficial Femoral Artery

BACKGROUND

This study aimed to examine a quantitative method for evaluating calcification in failure in recanalization (FR) in endovascular treatment of superficial femoral artery (SFA) chronic total occlusion, and to investigate the possibility of using a formula to predict the incidence of true lumen recanalization (TR) in such cases.

METHODS

Patients who met the inclusion criteria were retrospectively analyzed in our center from January 2012 to September 2017. A Calcification Lesion Analyzing and Scoring System (CLASS) was established to quantify the characteristics of calcification in SFA computed tomography slices, which were ranked as grade 1-4 and class A-E. Corresponding scores were obtained, and the Cumulative Calcification Score (CCS_O) of occlusive SFA was calculated on the basis of CLASS. The factors correlating to FR and the formula for predicting TR were evaluated.

RESULTS

A total of 215 patients were included in this study. There were 150 cases of TR and 65 cases of subintimal recanalization; 12 (5.6%) cases had FR. The maximum CLASS of occlusion was correlated with FR. Not only the formula including Trans-Atlantic Inter-Society Consensus II grade and CCS_O but also the formula including occlusion length and CCS_O predicted the incidence of TR well.

CONCLUSIONS

The degree of the most severe calcification in occlusive lesions clearly affects success in recanalization. Two quantitative formulas that combine occlusion length or Trans-Atlantic Inter-Society Consensus II grade with CCS_O can predict TR in endovascular treatment of SFA lesions with chronic total occlusion.

Lower extremity peripheral artery disease: a basic approach

Peripheral artery disease of the lower limbs is a chronically progressive disorder characterised by the presence of occlusive lesions in the medium and large arteries that result in symptoms secondary to insufficient blood flow to the lower extremities. It is both a manifestation of systemic atherosclerosis and a marker of increased cardiovascular morbidity and mortality. Because of its highly heterogenous clinical picture, a detailed history and physical assessment, a high degree of suspicion for peripheral artery disease and the use of the ankle-brachial pressure index is essential to identify patients with peripheral artery disease. This will allow early administration of basic pharmacotherapy and lifestyle changes to reduce cardiovascular events, minimise claudication symptoms and enable optimal revascularisation to prevent loss of limb function.

How To Assess a Claudication and When To Intervene

PURPOSE OF THE REVIEW

Peripheral artery disease (PAD) affects close to 200 million people worldwide. Claudication is the most common presenting symptom for patients with PAD. This review summarizes the current diagnostic and treatment options for patients with claudication. Comprehensive history and physical examination in order to differentiate between claudication secondary to vascular disease vs. neurogenic causes is paramount for initial diagnosis. Ankle-brachial index is the most commonly used test for screening and diagnostic purposes. Treatment consists of four different approaches, which are best utilized in combination: non-pharmacological treatment for claudication improvement, pharmacological treatment for claudication improvement, pharmacological treatment for secondary risk reduction, and interventional treatment for claudication improvement.

RECENT FINDINGS

Cilostazol is the only Food and Drug Administration (FDA)-approved agent for symptomatic treatment of claudication. Supervised exercise programs provide the maximum benefit for claudication improvement, but home-based exercise programs are an alternative. High-intensity statins and an antiplatelet agent should be prescribed to all patients with PAD. Angiotensin-converting-enzyme inhibitors can provide additional risk reduction, especially in patients with diabetes or hypertension. Rivaroxaban of low dosage (2.5 mg twice daily) in combination with aspirin further decreases cardiovascular risk, but this reduction comes at the cost of higher bleeding risk. Peripheral artery disease (PAD) is a form of atherosclerotic disease that affects hundreds of millions of people worldwide-one of its most common manifestations is intermittent claudication (IC), which results from insufficient blood flow to meet the metabolic demands of an affected extremity. This paper reviews the current literature regarding the workup, diagnosis, diagnostic modalities, treatment options, and management of intermittent claudication.

Assessment of Age-related Oxygenation Changes in Calf Skeletal Muscle by Photoacoustic Imaging: A Potential Tool for Peripheral Arterial Disease

Peripheral artery disease is often asymptomatic, and various imaging and nonimaging techniques have been used for assessment and monitoring treatments. This study is designed to demonstrate the ability of photoacoustic imaging to noninvasively determine changes in tissue oxygenation that occur in mice's hind limb skeletal muscle as they age. Mice from two age cohorts were scanned bilaterally with a pulsed laser. The photoacoustic signal was unmixed to generate a parametric map of estimated oxygen saturation and then overlaid on grayscale ultrasound images. Tissue oxygenation measured in young and old mice was compared. Photoacoustic imaging visually and quantitatively showed the decrease in skeletal muscle oxygenation that occurs with age. Percent tissue oxygenation decreased from 30.2% to 3.5% (p < 0.05). This reduction corresponded to reduced fractional area of oxygenation, which decreased from 60.6% to 6.0% (p < 0.05). The change in oxygenation capacity of the still active vascular regions was insignificant (p > 0.05). Intrasubject, intra-, and interobserver comparisons showed low variability in measurements, exhibited by high regression and intraclass correlations exceeding 0.81 for all ages. The decrease in oxygenation detected by photoacoustic imaging paralleled the known oxygenation decrease observed in aging tissues, demonstrating that photoacoustic imaging can assess age-related changes in a mouse calf muscle. These intramuscular changes could potentially act as a strong diagnostic marker for peripheral artery disease. This study thus opens the doors for a novel, affordable, noninvasive method of evaluation free of radiation or exogenous material.

Evaluation of the best single-energy scanning in energy spectrum CT in lower extremity arteriography

The present study aimed to apply the best single-energy (SE) scanning in energy spectrum computed tomography (CT) to evaluate the usefulness of lower extremity arterial angiography imaging in patients with lower extremity arterial occlusive disease. A total of 64 patients diagnosed with lower extremity arterial occlusive disease were randomly selected and divided into either the experimental group (n=32) or the control group (n=32). The two treatment groups were scanned for lower extremity arteriography using the best SE scanning mode of energy spectrum CT Gemstone imaging (GSI) and mixed energy scanning mode of multi-slice helical CT (MSCT). The CT images, image noise, contrast-to-noise ratio (CNR) and quality scores of the images of lower extremity arteries between the two groups were compared. Image quality of the two experimental groups were independently evaluated by two imaging diagnostic physicians. The CT scores and CNR of the lower extremity arteries were significantly higher in the experimental group compared with the control group (P<0.01). No statistically significant differences in the background noise between the two groups were observed (P<0.05). The image quality scores of two groups, with the differences between the two diagnosticians, were found to be statistically significant (P<0.01). In the lower extremity arterial angiography, the image quality of the best SE in the CT GSI scanning mode was observed to be superior to that taken using MSCT mixed energy scanning mode.

Applications of Cardiac Computed Tomography in the Cardio-Oncology Population

OPINION STATEMENT

The increased risk for cardiovascular events in aging cancer survivors and those undergoing certain chemotherapeutic treatments has raised concern for more rigorous screening and surveillance methods above that of the general population. At this time, there are limited guidelines for how to best manage this vulnerable cohort. Questions regarding timing of screening, choice of imaging modality and risk reduction strategies-especially in those patients with known atherosclerotic disease-remain to be elucidated. Over a decade of case series, retrospective studies and clinical trials have shed light on the evolving role of cardiac computed tomography (CT) in this population, of which there is a relative paucity of data regarding its potential utility in the specific cardio-oncology population. Focusing on ability of cardiac CT to evaluate multiple cardiac and vascular structures, provide diagnostic and prognostic information, as well as assist interventional and surgical colleagues in surgical/percutaneous valve replacement and revascularization strategies is the premise for this review.

Association of Peripheral Vascular Disease With Complications After Total Ankle Arthroplasty

BACKGROUND

Despite limited evidence, peripheral vascular disease is often cited as a contraindication for total ankle arthroplasty. The purpose of our study was to identify whether peripheral vascular disease in patients undergoing total ankle arthroplasty increased the rate of infection, postoperative irrigation and debridement, or failure of the implant.

METHODS

The PearlDiver Database was used to identify Medicare patients who underwent a total ankle arthroplasty from 2005 to 2014. These data were then analyzed for postoperative infections within 90 days, subsequent irrigation and debridements, and failure of total ankle arthroplasties. A diagnosis of preoperative peripheral vascular disease only included those patients who had peripheral vascular disease as an ICD-9 diagnosis code and underwent a preoperative lower extremity angiogram prior to total ankle arthroplasty. Medical comorbidities were identified using ICD-9 diagnosis codes. Three multivariable logistic regression models were then developed in order to identify risk factors associated with postoperative infections and failure after total ankle arthroplasty.

RESULTS

A total of 10 698 Medicare patients who underwent a primary total ankle arthroplasty were identified. There were 334 patients who had a postoperative infection within 90 days of their total ankle arthroplasty, and 95 of those patients required an irrigation and debridement. Regression analysis demonstrated that patients with peripheral vascular disease had the greatest risk of developing a postoperative infection within 90 days (OR 2.85, P < .01), requiring an irrigation and debridement postoperatively (OR 4.87, P < .001), and having a total ankle arthroplasty failure at any time point postoperatively (OR 2.51, P < .001).

CONCLUSIONS

Our study suggests that preoperative peripheral vascular disease is a significant risk factor for an acute postoperative infection, postoperative irrigation and debridement, and failure of the implant in Medicare patients undergoing a total ankle arthroplasty.

LEVEL OF EVIDENCE

Level III, therapeutic.

Modified calcium subtraction in dual-energy CT angiography of the lower extremity runoff: impact on diagnostic accuracy for stenosis detection

OBJECTIVES

To investigate the diagnostic accuracy of a modified three-material decomposition calcium subtraction (CS) algorithm for the detection of arterial stenosis in dual-energy CT angiography (DE-CTA) of the lower extremity runoff compared to standard image reconstruction, using digital subtraction angiography (DSA) as the reference standard.

METHODS

Eighty-eight patients (53 males; mean age, 65.9 ± 11 years) with suspected peripheral arterial disease (PAD) who had undergone a DE-CTA examination of the lower extremity runoff between May 2014 and May 2015 were included in this IRB-approved, HIPAA-compliant retrospective study. Standard linearly blended and CS images were reconstructed and vascular contrast-to-noise ratios (CNR) were calculated. Two independent observers assessed subjective image quality using a 5-point Likert scale. Diagnostic accuracy for ≥ 50% stenosis detection was analyzed in a subgroup of 45 patients who had undergone additional DSA. Diagnostic accuracy parameters were estimated with a random-effects logistic regression analysis and compared using generalized estimating equations.

RESULTS

CS datasets showed higher CNR (15.3 ± 7.3) compared to standard reconstructions (13.5 ± 6.5, p < 0.001). Both reconstructions showed comparable qualitative image quality scores (CS, 4.64; standard, 4.57; p = 0.220). Diagnostic accuracy (sensitivity, specificity, positive and negative predictive values) for CS reconstructions was 96.5% (97.5%, 95.6%, 90.9%, 98.1) and 93.1% (98.8%, 90.4%, 82.3%, 99.1%) for standard images.

CONCLUSIONS

A modified three-material decomposition CS algorithm provides increased vascular CNR, equivalent qualitative image quality, and greater diagnostic accuracy for the detection of significant arterial stenosis of the lower extremity runoff on DE-CTA compared with standard image reconstruction.

KEY POINTS

• Calcified plaques may lead to overestimation of stenosis severity and false positive results, requiring additional invasive digital subtraction angiography (DSA). • A modified three-material decomposition algorithm for calcium subtraction provides greater diagnostic accuracy for the detection of significant arterial stenosis of the lower extremity runoff compared with standard image reconstruction. • The application of this algorithm in patients with heavily calcified vessels may be helpful to potentially reduce inconclusive CT angiography examinations and the need for subsequent invasive DSA.

Modeling of the hemodynamics in the feet of patients with peripheral artery disease

To simulate the hemodynamic effects in the feet in response to a thigh cuff occlusion, we have developed a multi-compartmental model in which the circulatory system for the leg is represented by its electrical equivalents. Dynamic vascular optical tomographic imaging data previously obtained from 20 patients with peripheral artery disease (PAD) and 20 healthy subjects is used to test the model. Analyzing the clinical data with the support of the model yields diagnostic specificity and sensitivity in the 90-95% range, significantly higher than previously reported.

Photoacoustic computed tomography of human extremities

We present a method of imaging angiographic structures in human extremities, including hands, arms, legs, and feet, using a newly developed photoacoustic computed tomography (PACT) system. The system features deep penetration (1.8 cm in muscular tissues) with high spatial and temporal resolutions. A volumetric image is acquired within 5 to 15 s while each cross sectional image is acquired within 100  μs. Therefore, we see no blurring from motion in the imaging plane. Longitudinal and latitudinal cross-sectional images of a healthy volunteer clearly show the vascular network of each appendage and highlight the system's ability to image major and minor vasculatures, without the use of an external contrast or ionizing radiation. We also track heartbeat-induced arterial movement at a two-dimensional frame rate of 10 Hz. This work substantiates the idea that PACT could be used as a noninvasive method for imaging human vasculatures.

ACC/AHA/SCAI/SIR/SVM 2018 Appropriate Use Criteria for Peripheral Artery Intervention: A Report of the American College of Cardiology Appropriate Use Criteria Task Force, American Heart Association, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, and Society for Vascular Medicine

The American College of Cardiology (ACC) collaborated with the American Heart Association, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, and Society for Vascular Medicine, along with several ACC Councils, to establish and evaluate Appropriate Use Criteria (AUC) for peripheral artery intervention (PAI). Although PAI has been the subject of prior single-society papers, this is the first multisocietal effort on the topic.

To initiate the AUC process, patient scenarios that are common in clinical practice were drafted, along with assumptions and definitions for those scenarios. The scenarios were created using published guidelines, trial data, and expert opinions from within the field of peripheral artery disease. The writing group developed 45 clinical scenarios with up to 6 intervention options per scenario and categorized them into 6 general sections. A separate, independent rating panel evaluated each indication using a scoring scale from 1 to 9, thereby designating each indication as “Appropriate” (score of 7 to 9), “May Be Appropriate” (score of 4 to 6), or “Rarely Appropriate” (score of 1 to 3).

Throughout the scenarios, emphasis was placed on adhering to and exhausting medical therapy to achieve maximal benefit in those situations in which symptom management was desired or incidental disease was discovered. However, situations arise in which medical therapy is insufficient, and identifying a suitable revascularization strategy is necessary. After considering factors such as symptom burden, anatomic distribution, and ischemic burden, the rating panel determined that both endovascular and surgical approaches are Appropriate in clinical scenarios involving concomitant tissue loss or end organ compromise. There was a tendency to select endovascular approaches in these scenarios, particularly in anatomic distributions below the knee and where prior endovascular or surgical revascularization has been performed. Given the dynamic landscape of cardiovascular medicine, the writing group felt it was necessary to address situations in which adjunct arterial revascularization may be necessary to facilitate other procedures such as percutaneous valve replacement or hemodynamic support. The clinical situations where this occurs often make endovascular interventions more attractive and that was reflected in the ratings.

The purpose of this particular AUC is to provide guidance to clinicians who may refer patients for revascularization treatments and to interventionalists and surgeons themselves. With the field of peripheral artery disease constantly evolving, it is imperative to offer tools and resources that physicians can utilize to provide the best care for their patients.