Arterial Stiffness as a Biomarker of Radiation-Induced Carotid Atherosclerosis

Using ultrasound sequential images processing to predict radiotherapy-induced sternocleidomastoid muscle fibrosis

PURPOSE

The purpose of this study was to evaluate the thickness and biomechanical parameters of the sternocleidomastoid muscle (SCM) before, during, and after radiotherapy using ultrasound elastography to predict radiotherapy-induced muscle fibrosis.

MATERIALS AND METHODS

The mean daily absorbed doses of 20 SCMs were determined. To find out the Young and shear modulus, shear wave elastography (SWE) and the B-mode sequential images processing method were implemented. In the B-mode sequential images processing method, by administering dynamic stress, the Young and shear modulus were estimated utilizing the maximum gradient and the block-matching algorithms, respectively. The imaging was done before, during the third and sixth weeks of treatment, and 3 months after radiotherapy.

RESULTS

There was a statistically significant increase in the maximum thickness during the sixth week compared to before radiotherapy (p = .043). However, this parameter did not change significantly 3 months later (p = .095). The Young modulus (p = .611) derived from SWE did not differ significantly throughout any of the weeks of radiotherapy. But Young and shear modulus increased significantly in the B-mode sequential images processing method before and during the third and sixth weeks of treatment (p = .001). The outcomes observed 3 months after radiotherapy revealed a statistically significant increase in both Young modulus (p = .029) and shear modulus (p = .004) compared to pre-radiotherapy.

CONCLUSION

The Young modulus and shear modulus are introduced as biological markers used to detect the onset of the fibrosis process during the initial radiotherapy fractions.

Risk, prevention, screening and management of carotid artery stenosis in head & neck cancer patients-An evidence based review

Our review aims to clarify the incidence of carotid artery stenosis, risks of development, screening, management, and primary prevention strategies documented in the literature after radiation therapy for head and neck cancers. The high prevalence of carotid stenosis after radiation therapy for head and neck cancers has made surveillance and risk stratification critical. In addition to general cardiovascular risk factors such as smoking, diabetes, and dyslipidemia, risk factors for carotid artery stenosis after head and neck radiation included total plaque score, radiotherapy use and dosage, length of time after radiotherapy, and age greater than 50. Cancer subtype, namely nasopharyngeal cancer, may be correlated with increased risk as well, though contrasting results have been found. Interestingly, however, no significant relationship has been found between radiotherapy dose and stroke risk. Surgical management of post-radiation carotid stenosis is similar to that of stenosis unrelated to radiation, with carotid endarterectomy considered to be the gold standard treatment and carotid artery stenting being an acceptable, less-invasive alternative. Medical management of these patients has not been well-studied, but antiplatelet therapy, statins, and blood pressure control may be beneficial. The mainstay of screening for radiation-induced stenosis has been Doppler ultrasound, with measurement of changes in the intima-media thickness being a primary marker of disease development. A literature review was carried out using the MeSH terms "Carotid Artery Stenosis," "Head and Neck Neoplasms," and "Radiotherapy."

Carotid Artery Stenosis and Ischemic Stroke in Patients With Head and Neck Cancer Treated With Radiation Therapy: A Critical Review

The purpose of this review is to summarize the literature on carotid artery stenosis (CAS) and ischemic stroke (IS) in patients with head and neck cancer (HNC) treated with radiation therapy (RT) to guide assessment, screening, and management strategies. Patients treated with RT for HNC are at an elevated risk of developing CAS, with published meta-analyses demonstrating that CAS >50% occurs in approximately 25% of patients. Previous research suggests a 10-year cumulative incidence of stroke between 5.7% and 12.5%. Cardiovascular disease (CVD) risk prediction tools such as Qstroke, QRISK-2, and Framingham risk score perform poorly for predicting IS for patients with HNC who received RT. Duplex ultrasound is the most common imaging modality to assess CAS, but controversy remains as to the utility of screening asymptomatic individuals. Only 3 of the 5 major HNC survivorship guidelines acknowledge RT as a risk factor for CAS or IS, while only 1 makes a specific recommendation on screening for CAS (American Head and Neck Society). Within the general population, only 1 CVD guideline discusses RT as a risk factor for CAS (Society for Vascular Surgery). Clinicians involved in the care of patients with HNC treated with RT should be aware of the increased risk of CAS and IS and the challenges in risk prediction. Although there is a lack of evidence to make firm recommendations, HNC survivorship recommendations should ensure HNC survivors and primary care providers are informed of these risks and the importance of assessment and management of CVD risk factors. Future studies are required to refine risk prediction models in patients with HNC and to determine those most likely to benefit from targeted screening and initiation of early preventative strategies.

Longitudinal changes in the carotid arteries of head and neck cancer patients following radiation therapy: Results from a prospective serial imaging biomarker characterization study

INTRODUCTION

We prospectively evaluated morphologic and functional changes in the carotid arteries of patients treated with unilateral neck radiation therapy (RT) for head and neck cancer.

METHODS

Bilateral carotid artery duplex studies were performed at 0, 3, 6, 12, 18 months and 2, 3, 4, and 5 years following RT. Intima media thickness (IMT); global and regional circumferential, as well as radial strain, arterial elasticity, stiffness, and distensibility were calculated.

RESULTS

Thirty-eight patients were included. A significant difference in the IMT from baseline between irradiated and unirradiated carotid arteries was detected at 18 months (median, 0.073 mm vs -0.003 mm; P = 0.014), which increased at 3 and 4 years (0.128 mm vs 0.013 mm, P = 0.016, and 0.177 mm vs 0.023 mm, P = 0.0002, respectively). A significant transient change was noted in global circumferential strain between the irradiated and unirradiated arteries at 6 months (median difference, -0.89, P = 0.023), which did not persist. No significant differences were detected in the other measures of elasticity, stiffness, and distensibility.

CONCLUSIONS

Functional and morphologic changes of the carotid arteries detected by carotid ultrasound, such as changes in global circumferential strain at 6 months and carotid IMT at 18 months, may be useful for the early detection of radiation-induced carotid artery injury, can guide future research aiming to mitigate carotid artery stenosis, and should be considered for clinical surveillance survivorship recommendations after head and neck RT.

Comparison of Arterial Stiffness and Strain Measured with Speckle Tracking Carotid Strain Ultrasonography after Radiation and Surgical Treatment for Head and Neck Cancer-A Clinical Trial

This study assessed arterial stiffness in head and neck cancer patients using speckle tracking carotid strain ultrasonography (STCS-US). It investigated the impacts of neck irradiation and neck dissection on the arterial stiffness of these patients by comparing their stiffness parameters with those of healthy controls. A total of 101 participants (67 patients and 34 healthy controls) were enrolled in this study. Fifty-two patients received definitive radiation therapy (TD: 60-72 Gy in 30 days) at least two years ago. Participants were grouped into four according to their states of neck irradiation (IR) and neck dissection (ND): Group (IR+/ND-) had 28 patients, Group (IR+/ND+) had 24 patients, Group (IR-/ND+) had 15 patients, and Group (IR-/ND-) had 34 healthy controls. All the participants underwent STCS-US. Arterial stiffness parameters relating to arterial compliance (AC) and elastic modulus (EM) were significantly changed in Group (IR+/ND-) and Group (IR+/ND+) in the transverse plane (p < 0.001, p < 0.001) and in the longitudinal plane (p < 0.001, p < 0.001); the change in β-stiffness index (β-SI) was more significant in the transverse plane (p = 0.002). Group (IR+/ND+) had significant transverse circumferential (p = 0.001) and radial strain parameters (p = 0.001). The carotid intimal medial thickness (CIMT) significantly changed in Group (IR+/ND+) compared to controls (p = 0.001). Our findings indicate that neck irradiation and neck dissection increase arterial stiffness as single treatments; however, double treatment is associated with a higher increase. Neck irradiation affects strain parameters more than neck dissection alone. The study demonstrated the feasibility and clinical value of the STCS method in assessing arterial stiffness and its potential use in cardiovascular risk assessment for patients with head and neck cancer.

The Relationship Between Cancer and Functional and Structural Markers of Subclinical Atherosclerosis: A Systematic Review and Meta-Analysis

Objectives

The relationship between cancer and subclinical atherosclerosis has always been the focus of people's attention. We conducted a systematic review and meta-analysis by evaluating the effects of cancer on functional and structural markers of subclinical atherosclerosis:intima-media thickness (IMT), pulse wave velocity (PWV), and flow-mediated vasodilation (FMD).

Methods

A comprehensive and systematic literature search was conducted on the internet. Sensitivity analysis, publication bias, standard mean difference (SMD), corresponding 95% confidence interval (95% CI), and subgroup analysis were performed for all relevant research indicators in the retrieved literature.

Results

Forty-six studies were included, including 3,729 cancer patients and 2,404 healthy controls. Cancer patients had significantly thicker IMT [SMD (95%CI) = 0.290 (0.069 to 0.511), P = 0.010] and higher PWV [SMD (95%CI) = 0.392 (0.136 to 0.647), P = 0.003] compared with healthy controls. There was no significant difference in FMD [SMD (95% CI) = −0.192 (−0.527 to 0.144), P > 0.05). After subgrouping by age, male proportion, and treatment, the analysis results of IMT ≥ 50 years old, PWV and FMD < 50 years old, male proportion ≥50%, chemotherapy group, IMT and PWV radiotherapy group, and PWV endocrine therapy group were statistically significant (P < 0.05). There were no significant differences in other subgroup analyses, overall sensitivity analysis, and publication bias (p < 0.05).

Conclusions

Cancer may promote subclinical atherosclerosis, and change the functional and structural markers of subclinical atherosclerosis such as IMT and PWV. Early intervention and prevention should be pursued.

Late onset cardiovascular dysfunction in adult mice resulting from galactic cosmic ray exposure

The complex and inaccessible space radiation environment poses an unresolved risk to astronaut cardiovascular health during long-term space exploration missions. To model this risk, healthy male c57BL/6 mice aged six months (corresponding to an astronaut of 34 years) were exposed to simplified galactic cosmic ray (GCR5-ion; 5-ion sim) irradiation at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratories (BNL). Multi-modal cardiovascular functional assessments performed longitudinally and terminally revealed significant impairment in cardiac function in mice exposed to GCR5-ion compared to unirradiated controls, gamma irradiation, or single mono-energetic ions (56Fe or 16O). GCR5-ion-treated mice exhibited increased arterial elastance likely mediated by disruption of elastin fibers. This study suggests that a single exposure to GCR5-ion is associated with deterioration in cardiac structure and function that becomes apparent long after exposure, likely associated with increased morbidity and mortality. These findings represent important health considerations when preparing for successful space exploration.

Carotid intima-media thickness/diameter ratio and peak systolic velocity as risk factors for neurological severe ischemic events in Takayasu's arteritis

Objective

To characterize Takayasu arteritis (TAK) with supra-aortic involvement and determine the associations between clinical features, carotid ultrasonographic (US) parameters, and neurological severe ischemic events (SIE).

Methods

Patients with supra-aortic involvement including brachiocephalic trunk, bilateral common carotid artery and internal carotid artery, and bilateral subclavian and vertebral artery and baseline carotid US examination were enrolled from the East China Takayasu arteritis cohort. Bilateral carotid diameter, intima-media thickness (IMT), and peak systolic velocity (PSV) were measured by US. Then, IMT/diameter ratio (IDR) was calculated. Risk factors associated with neurological SIE were analyzed by multivariate logistic regression.

Results

Totally, 295 patients were included, of whom 260 (88.14%) were female, and 93 (31.53%) experienced neurological SIE. Involved supra-aortic artery distribution (p=0.04) and number (p<0.01) differed between neurologic and non-neurologic SIE subjects, showing higher prevalence of common carotid and vertebral artery involvement after Bonferroni correction and 56.99% patients having more than four involved arteries in neurological SIE group. The bilateral IDR (p<0.01) differed between patients with and without neurological SIE. The carotid IDR (left: cut-off value ≥0.55, odds ratio [OR] 2.75, 95% confidence interval [CI] 1.24-6.07, p=0.01; right: ≥0.58, OR 2.70, 95% CI 1.21-6.02, p=0.01) and left carotid PSV (≤76.00 cm/s, OR 3.09; 95% CI 1.53-6.27; p<0.01) as well as involved supra-aortic artery number (≥4, OR 2.33, 95% CI 1.15-4.72, p =0.02) were independently associated with neurological SIE.

Conclusion

The carotid IDR and PSV might be performed as valuable markers for recognizing neurological SIE in TAK patients with supra-aortic lesions.

Arterial stiffness as an ultrasound biomarker of radiation-induced carotid artery disease

Background: Radiation-induced carotid artery disease (RICAD) is an important issue in head and neck cancer (HNC) survivors after radiotherapy (RT). The risk of cerebrovascular disease in these patients is doubled. The aim of this study was to assess the effect of RT on carotid artery stiffness in HNC patients. Patients and methods: Conventional arterial stiffness parameters were measured in a total of 50 HNC survivors treated with RT for at least 5 years and compared to 50 unirradiated HNC patients. Elastic modulus (Ep) and Beta stiffness index (β) were measured in proximal, mid and distal common carotid artery (CCA). Results: The mean age of the subjects was 68±9 years (range: 44-84) in the irradiated group and 67±10 years (range: 45-85) in the control group. The RT group was treated with a mean radiation exposure of 60.3±6.7 Gy (range: 44-72) in the neck. Carotid stiffness parameters showed significant group differences: Ep in the RT group was 2.329±1.222 vs 1.742±828 in the non-RT group (p=0.006) and β index in the RT group was 23±11 vs 15±8 in the non-RT group (p<0.001). Radiation-induced carotid stiffness was quantified and cervical exposure to RT increased Ep in 575 kPa (p=0.014) and β in 7 units (p<0.003). Conclusions: Ep and β index could be suitable ultrasound biomarkers of radiation-induced atherosclerosis in HNC survivors. Further prospective studies are needed to feature RICD in this setting.

Assessing the short-term effects of radiotherapy on the shear modulus of the common carotid artery as a new biomarker of radiation-induced atherosclerosis

Purpose

The purpose of this study was to investigate the incidence of short-term atherosclerosis in the common carotid arteries following radiotherapy.

Methods

The mean radiation dose to the arteries was 49.30±15.83 Gy. A computational ultrasound method was introduced to investigate the elastic modulus. Ultrasonography was performed 2-3 cm inferior to the bifurcation region before and after radiotherapy, and sequential images were extracted from a video of each artery. Instantaneous movement of the arterial wall in the radial and longitudinal directions was extracted by implementing the maximum gradient and block matching algorithms, respectively.

Results

There was a significant change in systolic blood pressure after radiotherapy (P=0.008). Irradiated arteries had significantly smaller systolic and end-diastolic diameters than non-irradiated arteries (P<0.001). The shear modulus was significantly different between irradiated and non-irradiated arteries (3.10±2.03 kPa vs. 1.38±0.98 kPa, P<0.001). The shear and Young moduli of radiation-induced arteries were 2.25±1.50 and 1.57±0.59 times higher than those of the pre-irradiation arteries.

Conclusion

The arterial shear modulus can be considered as a new biomarker of radiation-induced atherosclerosis in the common carotid artery.

Effect of radiation on endothelial functions in workers exposed to radiation

OBJECTIVE Our aim is to determine whether radiation affects the endothelial function of hospital staff working in the radiation unit for diagnostic and therapeutic purposes. We have evaluated endothelial function with vascular imaging parameters such as flow-mediated dilatation (FMD) and aortic stiffness index (ASI). METHODS A total of 75 employees, 35 of whom are exposed to radiation due to their profession and 40 as the control group, were included in our single-centered study. Demographic data, FMD, aortic stiffness, and echocardiographic findings of the two groups were compared. RESULTS There were no significant differences in demographic data. Median FMD values tended to be lower in the radiation exposure group [7.89 (2.17-21.88) vs. 11.69 (5.13-27.27) p=0.09]. The FMD value was significantly lower in the catheter laboratory group than in the radiation-exposed (p=0.034) and control (p=0.012) groups. However, there was no statistically significant difference between the non-catheter lab radiation exposed group and the control group (p=0.804). In addition, there was no statistically significant difference in the ASI value between the groups (p=0.201). CONCLUSION We have found that FMD is decreased among hospital staff working in radiation-associated areas. This may be an early marker for radiation-induced endothelial dysfunction.

Medical prevention and treatment of radiation-induced carotid injury

Radiotherapy has significantly improved the survival of cancer patients but is also associated with several adversities, including radiation-induced carotid injury (RICI). The RICI mechanisms are complex, including vessel inflammatory injury, carotid atherosclerosis, intimal proliferation, media necrosis, and peri-adventitial fibrosis. The main manifestation and adverse consequence of RICI is carotid artery stenosis (CAS), which can lead to stroke and transient ischemic attack. Currently, carotid artery injury is primarily diagnosed via color-coded duplex sonography. Early detection of traumatic changes in the carotid artery depends on measurements of carotid intima-media thickness; serum biomarker testing also shows great potential. CAS is mainly treated with carotid endarterectomy or carotid angioplasty and stent implantation. Notably, bone marrow mesenchymal stem cells are advantageous in RICI treatment and reduce carotid inflammation, oxidative stress, and delaying atherosclerosis. This review summarizes the mechanisms, examination methods, and latest treatments for RICI to provide data for its clinical prevention and treatment.

Dose-dependent 60Co γ-radiation Effects on Human Endothelial Cell Mechanical Properties

Exposure to ionizing radiation is unavoidable for noncancerous cells during the external radiotherapy process. Increasing the dose delivery fraction times leads to increasing the endothelial cell damage. Vascular abnormalities are commonly associated with the alternation of endothelium biomechanical properties. The goal of the present study was to quantify the elastic and viscoelastic properties of human umbilical vein endothelial cells (HUVECs) using the micropipette aspiration technique in conjunction with a theoretical model while an 8 Gy dose was given in four fractions. Confocal imaging was performed for evaluation of cytoskeletal changes during fractionation ⁶⁰Co radiotherapy. The results indicated an increase in elastic modulus from 29.87 ± 1.04 Pa to 46.69 ± 1.17 Pa while the fractional doses increased from 0 Gy to 8 Gy along with the obvious cytoskeletal changes. Moreover, in the creep behavior of radiated groups, a significant decrease was shown in the time constant and viscoelastic properties. On the other hand, it was observed that the change in the biomechanical properties of the cells while applying a single fraction of 8 Gy was not exactly the same as that in the properties of the radiation-exposed cells while delivering an 8 Gy dose at 2 Gy per fraction. The observed differences in the biomechanical behavior of endothelium provide a quantitative description of radiobiological effects for evaluating the dose-response relationship as a biological dosimetry procedure.

The Effect of Microgravity on Central Aortic Blood Pressure

BACKGROUND

Blood pressure has been traditionally measured at peripheral arteries. In the past decade, evidence has grown that central aortic blood pressure may be a more powerful predictor for cardiovascular events, but data on its regulation are rare. The present work examines the impact of microgravity on central blood pressure for the first time.

METHODS

We performed 7 parabolic flights with 22 seconds of weightlessness in each parabola. Hemodynamic parameters including central systolic blood pressure were measured noninvasively in a free-floating position in 20 healthy subjects (19-43 years of age).

RESULTS

Arterial elasticity at rest was normal in all participants (augmentation index 14% (interquartile range (IQR) 10-22), pulse wave velocity 5.2 m/s (IQR 5.0-5.4)). Transition of 1g to 0g led to a significant increase of central systolic blood pressure from 124 (IQR 118-133) to 127 (IQR 119-133) mm Hg (P = 0.017). Cardiac index augmented significantly from 2.5 (IQR 2.2-2.8) to 2.7 (IQR 2.3-3.0) l/min/m2 (P < 0.001), while peripheral vascular resistance showed a decrease from 1.30 (IQR 1.14-1.48) to 1.25 (IQR 1.15-1.40) s × mm Hg/ml (P = 0.037). Peripheral systolic blood pressure did not change significantly (P > 0.05).

CONCLUSION

Whereas there is a multitude of studies on the effects of microgravity on peripheral blood pressure, this study provides first data on central aortic blood pressure. An acute loss of gravity leads to a central blood volume shift with an augmentation of cardiac output. In healthy subjects with normal arterial stiffness, the compensatory decrease of peripheral resistance does not outweigh this effect resulting in an increase of central blood pressure.

Hemodynamic analysis of radiation-induced damage in common carotid arteries by using color Doppler ultrasonography

Purpose

The aim of this study was to assess vascular changes and blood flow abnormalities in the common carotid arteries of patients with head and neck cancers after external radiotherapy, using color Doppler ultrasonography.

Methods

We studied 24 patients treated with external radiotherapy for various head and neck cancers. In order to study the acute effects of irradiation on common carotid blood flow and arterial diameter changes, color Doppler ultrasonography parameters such as peak systolic velocity, end diastolic velocity, mean velocity, systolic-to-diastolic velocity (S/D) ratio, pulsatility index (PI), resistive index (RI), and instantaneous diameter changes were evaluated before and after external radiotherapy. Additionally, the blood volume flow (VF) values in the peak systolic and end diastolic phases, as well as mean velocity, were evaluated throughout three cardiac cycles using B-mode ultrasonic image processing.

Results

The findings showed significant changes in the S/D ratio, PI, and RI of the common carotid arteries before and after external radiotherapy (P<0.05). Moreover, a significant decrease in artery diameter and blood VF was observed after radiotherapy relative to the pretreatment values. A significant correlation was found between the blood VF values estimated using ultrasonic measurements and mathematical methods throughout three cardiac cycles.

Conclusion

The hemodynamic parameters of the common carotid arteries changed during radiotherapy. These arterial changes may lead to late adverse effects of radiotherapy, such as ischemic strokes and ischemic attacks.

Arterial stiffness in hematologic malignancies

Malignant and cardiovascular disorders are the top causes of mortality worldwide. This article reviews the main literature data and mechanisms linking hematologic malignancies and arterial stiffness, focusing on recent experimental and clinical results. Several links were found in hematologic malignancies between complete blood count and arterial stiffness. Chemotherapy, especially anthracyclines, cyclophosphamide and tyrosine kinase inhibitors, as well as radiotherapy and hematopoietic stem cell transplantation are the main known causes of arterial stiffness increase in hematologic malignancies. The mechanisms of arterial stiffness elevation in hematologic malignancies include an increased oxidative stress, impaired vascular wall homeostasis, endothelial dysfunction and apoptosis of endothelial cells, overexpression of inflammatory cytokines, accelerated atherosclerosis, increased blood viscosity and unstable platelet aggregates. Guidelines regarding cardiovascular health screening and cardiovascular risk scores are necessary for hematologic cancer survivors in order to improve prognosis and quality of life of the patients.

Intensity-modulated radiotherapy for early glottic cancer: transition to a new standard of care?

For decades, the standard of care for radiation treatment of early larynx cancers has been conventional treatment using opposed lateral fields encompassing the larynx and overlying neck structures, including the adjacent carotid arteries. While intensity-modulated radiotherapy (IMRT) has replaced conventional radiotherapy for all other head/neck cancer situations, the use of IMRT to treat early glottic cancers remains controversial. The article reviews the published experience with IMRT for this clinical situation and provides a detailed review of the literature on radiation-induced carotid toxicity and how it might apply to the controversy. Finally, we discuss whether the radiation oncology community should transition to IMRT as a new standard of care for the treatment of early glottic cancers.