Publications by authors named "Mafalda Correia"

19 Publications

  • Page 1 of 1

Smart ultrasound device for non-invasive real-time myocardial stiffness quantification of the human heart.

IEEE Trans Biomed Eng 2021 Jun 7;PP. Epub 2021 Jun 7.

Quantitative assessment of myocardial stiffness is crucial to understand and evaluate cardiac biomechanics and function. Despite the recent progresses of ultrasonic shear wave elastography, quantitative evaluation of myocardial stiffness still remains a challenge because of strong elastic anisotropy. In this paper we introduce a smart ultrasound approach for non-invasive real-time quantification of shear wave velocity (SWV) and elastic fractional anisotropy (FA) in locally transverse isotropic elastic medium such as the myocardium. The approach relies on a simultaneous multidirectional evaluation of the SWV without a prior knowledge of the fiber orientation. We demonstrated that it can quantify accurately SWV in the range of 1.5 to 6 m/s in transverse isotropic medium (FA<0.7) using numerical simulations. Experimental validation was performed on calibrated phantoms and anisotropic ex vivo tissues. A mean absolute error of 0.22 m/s was found when compared to gold standard measurements. Finally, in vivo feasibility of myocardial anisotropic stiffness assessment was evaluated in four healthy volunteers on the antero-septo basal segment and on anterior free wall of the right ventricle (RV) in end-diastole. A mean longitudinal SWV of 1.08 0.20 m/s was measured on the RV wall and 1.74 0.51 m/s on the Septal wall with a good intra-volunteer reproducibility (0.18 m/s). This approach has the potential to become a clinical tool for the quantitative evaluation of myocardial stiffness and diastolic function.
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http://dx.doi.org/10.1109/TBME.2021.3087039DOI Listing
June 2021

Prognostic Value of Charlson Comorbidity Index in Acute Embolic Lower Limb Ischaemia Patients.

Ann Vasc Surg 2021 May 2. Epub 2021 May 2.

Angiology and Vascular Surgery Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.

Introduction: Charlson Comorbidity Index (CCI) is commonly used in outcome studies to adjust for patient comorbid conditions but has not been specifically validated for use in acute embolic lower limb ischaemia (AELLI).

Objectives: The aim of this study was to access whether a high CCI score unadjusted (CCIu) and adjusted (CCIa) by age relates to major amputation and mortality after a first episode of AELLI.

Methods: The last 100 patients presenting with the first event of AELLI submitted to embolectomy at our Vascular Surgery Department were retrospectively evaluated. Patient characteristics, pre- and post-operative period variables were collected and CCIu and CCIa calculated. Survival predictors were analyzed using Cox regression. The area under the curve of the receiver operating characteristic curves was calculated to validate and determine the discriminating ability of CCIu and CCIa in predicting amputation rate and 30-day mortality. Youden index was used to determine the critical value. Survival analysis was performed with Kaplan-Meier method and differences between survival curves were tested with Log-Rank test. A P value of <0.05 was considered statistically significant.

Results: The mean age was 80.03±10.776 years and the mean follow-up 19.28±7.929 months. Amputation rate was 16%, 30-day mortality 21% and long-term mortality 42%. Patients with CCIu≥3 compared with patients with CCIu<3 had higher amputation rate (37.5% vs. 1.7%; OR:35.400), 30-day mortality (47.5% vs. 3.3%; OR:35.400) and global mortality (P=0.00). Also, patients with CCIa≥6 compared with patients with CCIa<6 had higher amputation rate (34.1% vs. 1.8%; OR:28.488), 30-day mortality (47.7% vs. 0.0%) and global mortality (P=0.00). Multivariate analysis showed that both CCIu and CCIa were independent predictors of amputation rate and 30-day mortality.

Conclusion: CCIu and CCIa have proven to be good predictors of amputation rate and survival, thus being a valuable prognostic factor in patients presenting with the first event of AELLI.
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http://dx.doi.org/10.1016/j.avsg.2021.04.022DOI Listing
May 2021

Change in Domains that Influence Quality of Life after Major Lower Limb Amputation in Patients with Peripheral Arterial Disease.

Ann Vasc Surg 2021 Feb 5. Epub 2021 Feb 5.

Angiology and Vascular Surgery Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.

Background: Recent guidelines raise the concept of the importance of health-related quality of life (QoL). Change in QoL after amputation in ischemic patients is not well described. We aim to evaluate the change in quality of life after major limb amputation in patients with peripheral arterial disease.

Methods: We retrospectively identified all patients submitted to above-knee amputation (AKA) and below-knee amputation in our vascular surgery department in a 2-year period. Trauma excluded. A vascular amputee adapted QoL questionnaire was administered comparing the last 2 weeks to the 2 weeks before amputation. It included subjective and objective questions adapted from WHOQoL-BREEF and SF-36 divided into specific domains of QoL (physical health, role physical, pain, social, and psychological health) that were compared to 2 global items (overall QoL and general health). Independent samples tests and linear correlations were calculated.

Results: A total of 106 patients were included, 30-day mortality rate 16.3% and 1-year 39.1%. Patients had an increase in mean total score after amputation of 14.35 out of 100 points, with an improvement of 52.1 points in pain and 11 points in social and psychological health out of 100 (P<0.001). Physical health and role physical scores decreased after amputation. Overall QoL was correlated with total score (P<0.001). Mean QoL total score after amputation was 79.0% ± 12.6. In general, amputees scored higher in the domains social and psychological health. Older people, women, AKA and bilateral amputees had lower physical health scores (P<0.05), prosthesis was correlated with improvement in physical health after amputation (P = 0.026). Elderly and married people had big improvement in overall QoL after amputation (P = 0.008 and P = 0.056, respectively).

Conclusions: QoL does not seem to diminish in advanced ischemic patients after amputation. Older people value more a decrease in pain and family support over physical health. Therefore, patient oriented treatments should be preferred. Future research should be made to validate a disease-specific questionnaire for this population.
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http://dx.doi.org/10.1016/j.avsg.2021.01.082DOI Listing
February 2021

Impact of Total Psoas Area and Lean Muscular Area on Mortality after Endovascular Aortic Aneurysm Repair.

Ann Vasc Surg 2021 Apr 16;72:479-487. Epub 2020 Sep 16.

Angiology and Vascular Surgery Department, Centro Hospitalar e Universitário de Coimbra, EPE, Praceta Professor Mota Pinto, Coimbra, Portugal.

Background: Sarcopenia has assumed growing relevance as a morbimortality predictor after major abdominal surgery. The aim of this study is to access total psoas muscle area (TPA) and lean muscle area (LMA) impact in morbimortality after elective endovascular abdominal aortic aneurysm repair (EVAR).

Methods: Asymptomatic patients submitted to aortic endoprosthesis implantation between January 1, 2014 and December 31, 2018 at our vascular surgery department were retrospectively evaluated. After exclusion criteria were applied, 105 patients were included in the study; preoperative computed tomography scans were evaluated using OSIRIX software (Bernex, Switzerland). Two observers independently calculated TPA at the most caudal level of the L3 vertebra and respective density, therefore calculating LMA. Patients were separated by tertiles with the lowest being considered sarcopenic and with higher muscle steatosis and compared with the higher tertiles. Patient demographics and intraoperative and postoperative period variables were collected. Charlson comorbidity index was calculated and surgical complications classified according to Clavien-Dindo. The intraclass correlation coefficient and Bland-Altman plot were made to characterize interobserver variability. Survival analysis was performed with the Kaplan-Meier method, and differences between survival curves were tested with the log-rank test. The effect of sarcopenia on patient survival was assessed using Cox proportional hazard models.

Results: Considering TPA, univariate analyses revealed that patients in the lower tertile had inferior survival (P = 0.03), whereas multivariate analyses showed increased likelihood of mortality (P = 0.039, hazard ratio (HR) 3.829). For LMA, univariate analyses revealed that patients in the lower tertile had inferior survival (P = 0.013), whereas multivariate analyses showed increased likelihood of mortality (P = 0.026, HR 4.153). When analyzing patients in the lowest tertile of both TPA and LMA, both univariate (P = 0.002) and multivariate (P = 0.018, HR 4.166) analyses reveled inferior survival.

Conclusions: Our study reveals reduced survival in patients with low TPA and low LMA submitted to elective EVAR; these factors should probably be taken into consideration in the future for preoperative risk evaluation and surgical planning.
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http://dx.doi.org/10.1016/j.avsg.2020.09.004DOI Listing
April 2021

Is There an Impact of COVID-19 on Admission of Patients to the Emergency Department for Vascular Surgery?

Ann Vasc Surg 2020 Nov 11;69:100-104. Epub 2020 Aug 11.

Cirurgia Vascular, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.

Background: On March 2020, the World Health Organization declared the coronavirus disease 2019 outbreak a pandemic. During this period, surgical activity and admission to the Emergency Department (ED) decreased globally. The aim of this article is to understand how the admission of a patient to the ED for vascular surgery changed in our center in Portugal and if this situation prevented urgent surgical procedures.

Methods: Through a retrospective study, we compared the volume of patients admitted to the ED during the emergency state (ES) in Portugal with the same period in 2019. In addition, we analyzed the urgent surgical activity during the ES and in the correspondent period of the previous 10 years, regarding limb acute ischemia, acute aortic pathology, and vascular trauma. Two groups of patients were formed-patients operated during the ES and during the non-ES, for control. Statistical analysis was performed using IBM SPSS® Statistics, version 25.

Results: In the ES, 115 patients were observed at the ED and 179 in the 2019 corresponding period. During the ES, patients significantly recurred less to the ED directly from home (P < 0.001) and were less referred to the ED by primary care doctors (P < 0.001). Patients observed at the ED were significantly more urgent-required urgent surgery or were admitted to the department-than those in 2019 (40% vs. 24%). However, there were no differences when only considering urgent surgery (14% in ES vs. 10% in 2019). In the ES, 38% of patients observed at the ED were discharged with no follow-up related to vascular surgery against 60% in 2019, although this difference was not significant. Compared with the preceding 10 years, there are not significant differences in the number of patients who underwent urgent surgery in both ES and non-ES periods. In patients with acute limb ischemia, we did not find an increase in the time between onset of symptoms and ED admission, during the ES.

Conclusions: Fewer patients were admitted at the ED during the ES, and those admitted were significantly more urgent. We did not find a decrease in the number of urgent surgeries when compared with the preceding 10 years. Therefore, we cannot assume that coronavirus pandemic precluded urgent surgical procedures.
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http://dx.doi.org/10.1016/j.avsg.2020.08.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7417287PMC
November 2020

[The Impact of Patient Transfer After Rupture of an Abdominal Aortic Aneurysm].

Rev Port Cir Cardiotorac Vasc 2019 Oct-Dec;26(4):273-277

Serviço de Angiologia e Cirurgia Vascular, Centro Hospitalar e Universitário de Coimbra, Portugal.

Objective: determine whether patient transfer adversely affects the survival of ruptured abdominal aortic aneurysm (rAAA) patients after conventional surgery.

Methods: We performed a retrospective review of all patients undergoing attempted repair of an rAAA at a tertiary center, over January 2008 and December 2014. Patients were divided into those presenting directly to our center and those transferred from another hospital. The main outcome variable was 24-hour or 30-day mortality, with secondary variables including time to surgical treatment, length of intensive care unit stay and total length hospitalization.

Results: 78 patients (88% men) underwent attempted open repair of an rAAA during this period, 69% (54 cases) were transferred from another institution. Both groups were similar in terms of demographic characteristics, comorbidities and hemodynamic stability. The overall mortality rate was 51% at 30 days. Transferred patients took twice as long as direct patients to get to the operating room (median 7,9 vs. 3,9 horas, p < 0,05), Although the difference for surgery treatment, there was no difference in 24-hour and 30-day mortality between the transferred group and direct group (26% e 50% vs. 29% e 58%, p < 0,05). Mean intensive care unit stay (median, 12 vs. 4 dias, p = 0,04) and total hospitalization (median 11 vs. 4 dias, p = 0,04) were sustantially superior in the transferred group.

Conclusions: Transfer of patients with RAAA in this series results in a doubling of the time interval between initial patient presentation and arrival in the operating room. This, however, did not result in any disadvantage in the survival rate between the groups. The total length and resources consumption were higher in the transfer group. These results may be attributed to a pre-selection of patients (clinically stable) who are able to tolerate such a delay in surgical treatment, secondary to transfer.
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March 2020

4D functional ultrasound imaging of whole-brain activity in rodents.

Nat Methods 2019 10 23;16(10):994-997. Epub 2019 Sep 23.

Physics for Medicine Paris, INSERM U1273, ESPCI Paris, CNRS FRE 2031, PSL Research University, Paris, France.

We extended the capabilities of functional ultrasound to whole-brain four-dimensional (4D) neuroimaging. Our multiplane-wave transmission scheme on matrix arrays at thousands of frames per second provides volumetric recordings of cerebral blood volume changes at high spatiotemporal resolution. We illustrated the approach in rats while providing multiple sensory stimuli, for 4D functional connectivity and during instantaneous tracking of epileptiform events.
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http://dx.doi.org/10.1038/s41592-019-0572-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6774790PMC
October 2019

Ultrafast 3D Ultrasound Localization Microscopy Using a 32 × 32 Matrix Array.

IEEE Trans Med Imaging 2019 09 1;38(9):2005-2015. Epub 2019 Apr 1.

Ultrasound localization microscopy can map blood vessels with a resolution much smaller than the wavelength by localizing microbubbles. The current implementations of the technique are limited to 2-D planes or small fields of view in 3-D. These suffer from minute-long acquisitions, out-of-plane microbubbles, and tissue motion. In this paper, we exploit the recent development of 4D ultrafast ultrasound imaging to insonify an isotropic volume up to 20 000 times per second and perform localization microscopy in the three dimensions. Specifically, a 32 ×32 elements, 9-MHz matrix-array probe connected to a 1024-channel programmable ultrasound scanner was used to achieve sub-wavelength volumetric imaging of both the structure and vector flow of a complex 3D structure (a main canal branching out into two side canals). To cope with the large volumes and the need to localize the bubbles in the three dimensions, novel algorithms were developed based on deconvolution of the beamformed microbubble signal. For tracking, individual particles were paired following a Munkres assignment method, and velocimetry was done following a Lagrangian approach. ULM was able to clearly represent the 3-D shape of the structure with a sharp delineation of canal edges (as small as [Formula: see text]) and separate them with a spacing as low as [Formula: see text]. The compounded volume rate of 500 Hz was sufficient to describe velocities in 2.5-150-mm/s range and to reduce the maximum acquisition time to 12 s. This paper demonstrates the feasibility of in vitro 3-D ultrafast ultrasound localization microscopy and opens up the way toward in vivo volumetric ULM.
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http://dx.doi.org/10.1109/TMI.2018.2890358DOI Listing
September 2019

Adaptive Spatiotemporal Filtering for Coronary Ultrafast Doppler Angiography.

IEEE Trans Ultrason Ferroelectr Freq Control 2018 11;65(11):2201-2204

The heart's supply of oxygen and nutrients relies on the coronary vasculature, which branches from millimeter-sized arteries down to micrometer-sized capillaries. To date, imaging technologies can only detect large epicardial coronary vessels, whereas the intramural coronary vasculature remains invisible due to cardiac motion. We recently introduced coronary ultrafast Doppler angiography, a noninvasive vascular imaging technology based on ultrafast ultrasound that enables the visualization of epicardial and intramural coronary vasculature in humans. In this letter we describe, using an open-chest swine data set, the adaptive spatiotemporal filtering method that was developed for the detection of slow blood flows embedded in rapid myocardial motion.
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http://dx.doi.org/10.1109/TUFFC.2018.2870083DOI Listing
November 2018

True Brachial Artery Aneurysm in a Patient with Vascular Access for Haemodialysis and Kidney Graft.

Rev Port Cir Cardiotorac Vasc 2017 Jul-Dec;24(3-4):184

Serviço de Angiologia e Cirurgia Vascular do Centro Hospitalar e Universitário de Coimbra, Portugal.

Introduction: True brachial artery aneurysms are rare and some of them have been described as a late complication in patients with vascular access for haemodialysis and kidney graft. The purpose of this paper is to present a clinical case of a patient with a true brachial artery aneurysm and its following treatment.

Methods: This case concerns a caucasian male patient with 43 years old who had vesicoureteral reflux at 7 years old, and subsequent end-stage renal disease, and started on haemodialysis at the age of twelve. The patient had homolateral radial and brachiocephalic arteriovenous fistulas (AVF), two sequential kidney grafts and was under immunosuppressant therapy for several years. As part of the medical history he also had bilateral amaurosis, Hepatitis B and C and was submitted to total parathyroidectomy and a following auto-transplant. In the latest years the patient presented with several aneurysms related to the vascular access. After the finding of an anastomotic false aneurysm and venous aneurysms complicating the AVF, the patient had removal of the aneurysms and ligation of the AVF. Later, he was diagnosed, in different times, with two true brachial artery aneurysms. At the time of the diagnosis of the first true aneurysm, the patient presented with local pain and occasional paraesthesias relative to compression symptoms. At physical examination the patient had a brachial pulsatile mass and a palpable radial pulse. The Doppler ultrasound exam revealed a true brachial artery aneurysm with 4,5 cm diameter. After two years, the patient was once again diagnosed with a true brachial artery aneurysm with 3,1 cm diameter. At this time the patient was asymptomatic and had palpable brachial mass and radial pulse.

Results: At the time of the diagnosis of the first true brachial aneurysm the patient was submitted to partial aneurysmectomy and brachiobrachial graft with PTFE 8. The patency of the graft persisted until the diagnosis of the second aneurysm. After two years, the patient was submitted to partial aneurysmectomy and axilobrachial graft with PTFE 8. During the follow-up period, the patient remained asymptomatic, had palpable radial pulse and the Doppler ultrasound exam confirmed the patency of the graft.

Conclusion: The surveillance of patients with long duration AVF and kidney grafts might be advantageous in the early detection of arterial aneurysms. The surgical treatment in this group of patients is a first treatment option that is associated to a low morbidity.
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May 2019

Aneurysms of the Upper Limb: Review of an Experience.

Rev Port Cir Cardiotorac Vasc 2017 Jul-Dec;24(3-4):152

Serviço de Angiologia e Cirurgia Vascular do Centro Hospitalar e Universitário de Coimbra, Portugal.

Introduction: True arterial aneurysms of the upper limb are rare and their treatment is intended to avoid complications as distal embolization or compression of surrounding neurovascular structures. The purpose of this study is to review the experience in the surgical treatment of true arterial aneurysms of the upper limb.

Methods: Retrospective study of patients with true arterial aneurysms of the upper limb surgically treated between January 2007 and August 2017. Nine patients were identified and data was collected regarding sex, age, past medical history, aneurysm's aetiology, surgical procedure, complications and the need for re-intervention.

Results: From a total of nine patients, seven were male and two were female, with ages between 29 and 68 years old (medium age of 55,5). One of the patients had surgery twice because of two aneurysms of the upper limb. From a total of 10 cases, two were subclavian, one was axillary and seven were brachial aneurysms. Three of them had degenerative/idiopathic aetiology, one was associated to a cervical rib and six occurred in the setting of arteriovenous fistula or kidney graft. Three patients had emergent surgery and the others had elective surgery. All of them were submitted to aneurysmectomy. As 30-day complications, there were two haematomas, one compartment syndrome and two early graft occlusions. Four patients needed re-intervention. During the follow-up period, all the grafts initially preserved were patent. There were no further known complications or amputation procedures. One of the patients who had emergent surgery and presented with finger paresis remained with hypomotility after the surgery.

Conclusion: True arterial aneurysms of the upper limb are uncommon. In this review most of the aneurysms were found in patients with haemodialysis vascular access or kidney grafts. Despite the need for early re-intervention in some cases, the surgical treatment of true arterial aneurysms of the upper limb is a low morbidity procedure.
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May 2019

Abdominal Aortic Aneurysm in Women: Retrospective Analysis of the Cases that Undergo Surgical Repair.

Rev Port Cir Cardiotorac Vasc 2017 Jul-Dec;24(3-4):150

CHUC, Portugal.

Introduction: The prevalence of infra-renal aortic abdominal aneurysms (AAA) is about 3 to 4 times higher in men, with a recommendation I 1a for screening men > 65y. Althoug women only represente 20% of the total AAAs they have a significant higher rupture rate - threefold higher - and a worse outcome after ruptured AAA repair. Screening is not consensual but can be recommended for women > 65y who have smoked or have a family history of AAA. Against screening is the fact that the AAA in women have not only a lower incidence but also a late presentation (>80y) but references have been made to the fact that smoking became popular more than 30 years after than men and so the effects just now can start to be seen.

Methods: A retrospective review was made to all women with an infra- renal AAA who undergo a surgical treatment, elective or urgent, in the past 7 years (January 2010 - August 2017) in our hospital. Information was obtained through the clinical process. It was made an evaluation of the demographic information and anatomic features.

Results: 15 cases were reviewed, 4 elective and 11 ruptured surgical repairs. The mean age was 74 and only 4 women were more than 80 years old, with a minium age of 57. More than half the patients were previously diagnosis with hypertension but only 30% had high cholesterol. Only one was a known smoker. None had a diagnosis of cardiac disease. One had a sintomatic cerebrovascular disease. Within the elective cases, all open repair, the intra-hospitalar mortality was zero with a mean stay of 7,5 days. The ruptured cases, 1 endovascular, had a perioperative mortality of 50% The mean aortic diametre at rupture was less than 6 cm.

Conclusion: Data supports the evidence of the morbidity of a ruptured AAA and the high intra-hospitalar mortality in women. Early detection and elective repair should be considered. Sex-specific research is needed to provide the best medical treatment.
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May 2019

Myocardial Stiffness Evaluation Using Noninvasive Shear Wave Imaging in Healthy and Hypertrophic Cardiomyopathic Adults.

JACC Cardiovasc Imaging 2019 07 14;12(7 Pt 1):1135-1145. Epub 2018 Mar 14.

Hôpital Européen Georges Pompidou, Université Paris Descartes, Cardio-Vascular Departement, UMR 970, Paris, France.

Objectives: The goal of our study was to investigate the potential of myocardial shear wave imaging (SWI) to quantify the diastolic myocardial stiffness (MS) (kPa) noninvasively in adult healthy volunteers (HVs) and its physiological variation with age, and in hypertrophic cardiomyopathy (HCM) populations with heart failure and preserved ejection function (HFpEF).

Background: MS is an important prognostic and diagnostic parameter of the diastolic function. MS is affected by physiological changes but also by pathological alterations of extracellular and cellular tissues. However, the clinical assessment of MS and the diastolic function remains challenging. SWI is a novel ultrasound-based technique that has the potential to provide intrinsic MS noninvasively.

Methods: We prospectively included 80 adults: 60 HV (divided into 3 groups: 20- to 39-year old patients [n = 20]; 40- to 59-year-old patients [n = 20]; and 60- to 79-year-old patients [n = 20]) and 20 HCM-HFpEF patients. Echocardiography, cardiac magnetic resonance imaging and biological explorations were achieved. MS evaluation was performed using an ultrafast ultrasound scanner with cardiac phased array. The fractional anisotropy of MS was also estimated.

Results: MS increased significantly with age in the HV group (the mean MS was 2.59 ± 0.58 kPa, 4.70 ± 0.88 kPa, and 6.08 ± 1.06 kPa for the 20- to 40-year-old, 40- to 60-year-old, and 60- to 80-year-old patient groups, respectively; p < 0.01 between each group). MS was significantly higher in HCM-HFpEF patients than in HV patients (mean MS = 12.68 ± 2.91 kPa vs. 4.47 ± 1.68 kPa, respectively; p < 0.01), with a cut-off at 8 kPa (area under the curve = 0.993; sensitivity = 95%, specificity = 100%). The fractional anisotropy was lower in HCM-HFpEF (mean = 0.133 ± 0.073) than in HV (0.238 ± 0.068) (p < 0.01). Positive correlations were found between MS and diastolic parameters in echocardiography (early diastolic peak/early diastolic mitral annular velocity, r = 0.783; early diastolic peak/transmitral flow propagation velocity, r = 0.616; left atrial volume index, r = 0.623) and with fibrosis markers in cardiac magnetic resonance (late gadolinium enhancement, r = 0.804; myocardial T1 pre-contrast, r = 0.711).

Conclusions: MS was found to increase with age in healthy adults and was significantly higher in HCM-HFpEF patients. Myocardial SWI has the potential to become a clinical tool for the diagnostic of diastolic dysfunction. (Non-invasive Evaluation of Myocardial Stiffness by Elastography [Elasto-Cardio]; NCT02537041).
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http://dx.doi.org/10.1016/j.jcmg.2018.02.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6603249PMC
July 2019

Simultaneous positron emission tomography and ultrafast ultrasound for hybrid molecular, anatomical and functional imaging.

Nat Biomed Eng 2018 02 6;2(2):85-94. Epub 2018 Feb 6.

Inserm, UMR970, Paris Cardiovascular Research Center, Paris, France.

Positron emission tomography-computed tomography (PET-CT) is the most sensitive molecular imaging modality, but it does not easily allow for rapid temporal acquisition. Ultrafast ultrasound imaging (UUI)-a recently introduced technology based on ultrasonic holography-leverages frame rates of up to several thousand images per second to quantitatively map, at high resolution, haemodynamic, biomechanical, electrophysiological and structural parameters. Here, we describe a pre-clinical scanner that registers PET-CT and UUI volumes acquired simultaneously and offers multiple combinations for imaging. We demonstrate that PET-CT-UUI allows for simultaneous images of the vasculature and metabolism during tumour growth in mice and rats, as well as for synchronized multi-modal cardiac cine-loops. Combined anatomical, functional and molecular imaging with PET-CT-UUI represents a high-performance and clinically translatable technology for biomedical research.
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http://dx.doi.org/10.1038/s41551-018-0188-zDOI Listing
February 2018

Noninvasive Imaging of the Coronary Vasculature Using Ultrafast Ultrasound.

JACC Cardiovasc Imaging 2018 06 16;11(6):798-808. Epub 2017 Aug 16.

Institut Langevin, ESPCI ParisTech, CNRS UMR 7587, INSERM U979, Paris, France. Electronic address:

Objectives: The aim of this study was to investigate the potential of coronary ultrafast Doppler angiography (CUDA), a novel vascular imaging technique based on ultrafast ultrasound, to image noninvasively with high sensitivity the intramyocardial coronary vasculature and quantify the coronary blood flow dynamics.

Background: Noninvasive coronary imaging techniques are currently limited to the observation of the epicardial coronary arteries. However, many studies have highlighted the importance of the coronary microcirculation and microvascular disease.

Methods: CUDA was performed in vivo in open-chest procedures in 9 swine. Ultrafast plane-wave imaging at 2,000 frames/s was combined to an adaptive spatiotemporal filtering to achieve ultrahigh-sensitive imaging of the coronary blood flows. Quantification of the flow change was performed during hyperemia after a 30-s left anterior descending (LAD) artery occlusion followed by reperfusion and was compared to gold standard measurements provided by a flowmeter probe placed at a proximal location on the LAD (n = 5). Coronary flow reserve was assessed during intravenous perfusion of adenosine. Vascular damages were evaluated during a second set of experiments in which the LAD was occluded for 90 min, followed by 150 min of reperfusion to induce myocardial infarction (n = 3). Finally, the transthoracic feasibility of CUDA was assessed on 2 adult and 2 pediatric volunteers.

Results: Ultrahigh-sensitive cine loops of venous and arterial intramyocardial blood flows were obtained within 1 cardiac cycle. Quantification of the coronary flow changes during hyperemia was in good agreement with gold standard measurements (r = 0.89), as well as the assessment of coronary flow reserve (2.35 ± 0.65 vs. 2.28 ± 0.84; p = NS). On the infarcted animals, CUDA images revealed the presence of strong hyperemia and the appearance of abnormal coronary vessel structures in the reperfused LAD territory. Finally, the feasibility of transthoracic coronary vasculature imaging was shown on 4 human volunteers.

Conclusions: Ultrafast Doppler imaging can map the coronary vasculature with high sensitivity and quantify intramural coronary blood flow changes.
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http://dx.doi.org/10.1016/j.jcmg.2017.05.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5784807PMC
June 2018

4D ultrafast ultrasound flow imaging: in vivo quantification of arterial volumetric flow rate in a single heartbeat.

Phys Med Biol 2016 12 3;61(23):L48-L61. Epub 2016 Nov 3.

Institut Langevin, ESPCI Paris, PSL Research University, INSERM U979, CNRS UMR 7587, Université Paris Diderot - Sorbonne Paris Cité UMR 7587, UPMC Université Paris 06 - Sorbonne Universités UMR 7587, 17 rue Moreau, 75012 Paris, France.

We present herein 4D ultrafast ultrasound flow imaging, a novel ultrasound-based volumetric imaging technique for the quantitative mapping of blood flow. Complete volumetric blood flow distribution imaging was achieved through 2D tilted plane-wave insonification, 2D multi-angle cross-beam beamforming, and 3D vector Doppler velocity components estimation by least-squares fitting. 4D ultrafast ultrasound flow imaging was performed in large volumetric fields of view at very high volume rate (>4000 volumes s) using a 1024-channel 4D ultrafast ultrasound scanner and a 2D matrix-array transducer. The precision of the technique was evaluated in vitro by using 3D velocity vector maps to estimate volumetric flow rates in a vessel phantom. Volumetric Flow rate errors of less than 5% were found when volumetric flow rates and peak velocities were respectively less than 360 ml min and 100 cm s. The average volumetric flow rate error increased to 18.3% when volumetric flow rates and peak velocities were up to 490 ml min and 1.3 m s, respectively. The in vivo feasibility of the technique was shown in the carotid arteries of two healthy volunteers. The 3D blood flow velocity distribution was assessed during one cardiac cycle in a full volume and it was used to quantify volumetric flow rates (375  ±  57 ml min and 275  ±  43 ml min). Finally, the formation of 3D vortices at the carotid artery bifurcation was imaged at high volume rates.
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http://dx.doi.org/10.1088/0031-9155/61/23/L48DOI Listing
December 2016

Ultrafast Harmonic Coherent Compound (UHCC) Imaging for High Frame Rate Echocardiography and Shear-Wave Elastography.

IEEE Trans Ultrason Ferroelectr Freq Control 2016 Mar 15;63(3):420-31. Epub 2016 Feb 15.

Transthoracic shear-wave elastography (SWE) of the myocardium remains very challenging due to the poor quality of transthoracic ultrafast imaging and the presence of clutter noise, jitter, phase aberration, and ultrasound reverberation. Several approaches, such as diverging-wave coherent compounding or focused harmonic imaging, have been proposed to improve the imaging quality. In this study, we introduce ultrafast harmonic coherent compounding (UHCC), in which pulse-inverted diverging waves are emitted and coherently compounded, and show that such an approach can be used to enhance both SWE and high frame rate (FR) B-mode Imaging. UHCC SWE was first tested in phantoms containing an aberrating layer and was compared against pulse-inversion harmonic imaging and against ultrafast coherent compounding (UCC) imaging at the fundamental frequency. In vivo feasibility of the technique was then evaluated in six healthy volunteers by measuring myocardial stiffness during diastole in transthoracic imaging. We also demonstrated that improvements in imaging quality could be achieved using UHCC B-mode imaging in healthy volunteers. The quality of transthoracic images of the heart was found to be improved with the number of pulse-inverted diverging waves with a reduction of the imaging mean clutter level up to 13.8 dB when compared against UCC at the fundamental frequency. These results demonstrated that UHCC B-mode imaging is promising for imaging deep tissues exposed to aberration sources with a high FR.
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http://dx.doi.org/10.1109/TUFFC.2016.2530408DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4878711PMC
March 2016

Multiplane wave imaging increases signal-to-noise ratio in ultrafast ultrasound imaging.

Phys Med Biol 2015 Nov 21;60(21):8549-66. Epub 2015 Oct 21.

ESPCI-ParisTech, PSL University, INSERM U979, CNRS UMR7587, Institut Langevin, 1 rue Jussieu, F-75005, Paris, France.

Ultrafast imaging using plane or diverging waves has recently enabled new ultrasound imaging modes with improved sensitivity and very high frame rates. Some of these new imaging modalities include shear wave elastography, ultrafast Doppler, ultrafast contrast-enhanced imaging and functional ultrasound imaging. Even though ultrafast imaging already encounters clinical success, increasing even more its penetration depth and signal-to-noise ratio for dedicated applications would be valuable. Ultrafast imaging relies on the coherent compounding of backscattered echoes resulting from successive tilted plane waves emissions; this produces high-resolution ultrasound images with a trade-off between final frame rate, contrast and resolution. In this work, we introduce multiplane wave imaging, a new method that strongly improves ultrafast images signal-to-noise ratio by virtually increasing the emission signal amplitude without compromising the frame rate. This method relies on the successive transmissions of multiple plane waves with differently coded amplitudes and emission angles in a single transmit event. Data from each single plane wave of increased amplitude can then be obtained, by recombining the received data of successive events with the proper coefficients. The benefits of multiplane wave for B-mode, shear wave elastography and ultrafast Doppler imaging are experimentally demonstrated. Multiplane wave with 4 plane waves emissions yields a 5.8  ±  0.5 dB increase in signal-to-noise ratio and approximately 10 mm in penetration in a calibrated ultrasound phantom (0.7 d MHz(-1) cm(-1)). In shear wave elastography, the same multiplane wave configuration yields a 2.07  ±  0.05 fold reduction of the particle velocity standard deviation and a two-fold reduction of the shear wave velocity maps standard deviation. In functional ultrasound imaging, the mapping of cerebral blood volume results in a 3 to 6 dB increase of the contrast-to-noise ratio in deep structures of the rodent brain.
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http://dx.doi.org/10.1088/0031-9155/60/21/8549DOI Listing
November 2015