Ultrafast Flow Quantification With Segmented K-Space Magnetic Resonance Phase Velocity Mapping

Magnetic resonance (MR) phase-velocity mapping (PVM) is routinely being used clinically to measure blood flow velocity. Conventional nonsegmented PVM is accurate but relatively slow (3–5 min per measurement). Ultrafast k-space segmented PVM offers much shorter acquisitions (on the order of seconds instead of minutes). The aim of this study was to evaluate the accuracy of segmented PVM in quantifying flow from through-plane velocity measurements. Experiments were performed using four straight tubes (inner diameter of 5.6–26.2 mm), under a variety of steady (1.7–200 ml/s) and pulsatile (6–90 ml/cycle) flow conditions. Two different segmented PVM schemes were tested, one with five k-space lines per segment and one with nine lines per segment. Results showed that both segmented sequences provided very accurate flow quantification (errorsflow conditions, even under turbulent flow conditions. This agreement was confirmed via regression analysis. Further statistical analysis comparing the flow data from the segmented PVM techniques with (i) the data from the nonsegmented technique and (ii) the true flow values showed no significant difference (all p values≫0.05). Preliminary flow measurements in the ascending aorta of two human subjects using the nonsegmented sequence and the segmented sequence with nine lines per segment showed very close agreement. The results of this study suggest that ultrafast PVM has great potential to measure blood velocity and quantify blood flow clinically. © 2002 Biomedical Engineering Society

Accurate Quantification of Steady and Pulsatile Flow With Segmented K-Space Magnetic Resonance Velocimetry

Conventional non-segmented magnetic resonance phase velocity mapping (MRPVM) is an accurate but relatively slow velocimetric technique. Therefore, the aim of this study was to evaluate the accuracy of the much faster segmented k-space MRPVM in quantifying flow. The axial velocity was measured in four straight tubes (inner diameter: 5.6–26.2 mm), using a segmented MRPVM sequence with seven lines of k-space per segment. The flow rate and flow volume were accurately quantified (errorssteady (r2=0.99) and pulsatile flow (r2=0.98), respectively. The measured velocity profiles and flow rates from the segmented sequence agreed with those from the non-segmented (p\u3e0.05). Changing the slice thickness or the field of view did not affect the accuracy of the measurements. The results of this study suggest that fast, segmented MRPVM can be used for accurate flow quantification

Accurate Quantification of Steady and Pulsatile Flow With Segmented K-Space Magnetic Resonance Velocimetry

Conventional non-segmented magnetic resonance phase velocity mapping (MRPVM) is an accurate but relatively slow velocimetric technique. Therefore, the aim of this study was to evaluate the accuracy of the much faster segmented k-space MRPVM in quantifying flow. The axial velocity was measured in four straight tubes (inner diameter: 5.6–26.2 mm), using a segmented MRPVM sequence with seven lines of k-space per segment. The flow rate and flow volume were accurately quantified (errorssteady (r2=0.99) and pulsatile flow (r2=0.98), respectively. The measured velocity profiles and flow rates from the segmented sequence agreed with those from the non-segmented (p\u3e0.05). Changing the slice thickness or the field of view did not affect the accuracy of the measurements. The results of this study suggest that fast, segmented MRPVM can be used for accurate flow quantification

Ultrafast Flow Quantification With Segmented K-Space Magnetic Resonance Phase Velocity Mapping

Magnetic resonance (MR) phase-velocity mapping (PVM) is routinely being used clinically to measure blood flow velocity. Conventional nonsegmented PVM is accurate but relatively slow (3–5 min per measurement). Ultrafast k-space segmented PVM offers much shorter acquisitions (on the order of seconds instead of minutes). The aim of this study was to evaluate the accuracy of segmented PVM in quantifying flow from through-plane velocity measurements. Experiments were performed using four straight tubes (inner diameter of 5.6–26.2 mm), under a variety of steady (1.7–200 ml/s) and pulsatile (6–90 ml/cycle) flow conditions. Two different segmented PVM schemes were tested, one with five k-space lines per segment and one with nine lines per segment. Results showed that both segmented sequences provided very accurate flow quantification (errorsflow conditions, even under turbulent flow conditions. This agreement was confirmed via regression analysis. Further statistical analysis comparing the flow data from the segmented PVM techniques with (i) the data from the nonsegmented technique and (ii) the true flow values showed no significant difference (all p values≫0.05). Preliminary flow measurements in the ascending aorta of two human subjects using the nonsegmented sequence and the segmented sequence with nine lines per segment showed very close agreement. The results of this study suggest that ultrafast PVM has great potential to measure blood velocity and quantify blood flow clinically. © 2002 Biomedical Engineering Society

Clinical Blood Flow Quantification with Segmented k-Space Magnetic Resonance Phase Velocity Mapping

To evaluate the accuracy of segmented k-space magnetic resonance phase velocity mapping (PVM) in quantifying aortic blood flow from through-plane velocity measurements. Two segmented PVM schemes were evaluated, one with seven lines per segment (seg-7) and one with nine lines per segment (seg-9), in twenty patients with cardiovascular disease. A non-segmented (non-seg) PVM acquisition was also performed to provide the reference data. There was agreement between the aortic flow curves acquired with segmented and non-segmented PVM. The calculated systolic and total flow volume per cycle from the seg-7 and the seg-9 scans correlated and agreed with the flow volumes from the non-seg scans (differences \u3c 5%). Sign tests showed that there were no statistically significant differences (P-values \u3c 0.05) between the segmented and the non-segmented PVM measurements. Seg-9, which was the fastest among the three sequences, provided adequate spatial and temporal resolution (\u3e 10 phases per cycle)

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Cohort study of cardiovascular risk in asymptomatic young adults: subclinical atherosclerosis and coronary calcium score

Abstract Coronary artery calcification is an early marker of subclinical atherosclerosis, but little research has been done in asymptomatic individuals under 45 years. In this cohort study with 17 years of follow-up, 155 participants were assessed in 2016 with a coronary calcium score for the association with cardiovascular risk factors. During follow-up, there was a significant increase in anthropometric measurements, cholesterol and fractions, and diastolic pressure. Participants who gained 1 cm in waist circumference had a mean reduction of 0.36 mg/dL in HDL-cholesterol and those who gained 1 kg/m2 in body mass index had a reduction of 0.72 mg/dL in HDL-cholesterol. Married participants had a 4.78 mg/dL reduction in HDL-cholesterol levels compared to singles. There was an increase of 2.09 mg/dL in HDL-cholesterol at each higher level of self-perceived health. One single case, a 32-year-old male, smoker, sedentary individual with a family history of cardiovascular disease, presented coronary calcification (0.6%). His HDL-cholesterol was reduced by 43.4%, with levels of less than 25 mg/dL at the time of coronary calcium scoring. Our findings may prompt broader studies of populations under 35 years with HDL-C levels below 25 mg/dL and family histories of cardiovascular disease, associated with obesity, sedentary lifestyle and smoking

Reduction of cardiac imaging tests during the COVID-19 pandemic: The case of Italy. Findings from the IAEA Non-invasive Cardiology Protocol Survey on COVID-19 (INCAPS COVID)

Background: In early 2020, COVID-19 massively hit Italy, earlier and harder than any other European country. This caused a series of strict containment measures, aimed at blocking the spread of the pandemic. Healthcare delivery was also affected when resources were diverted towards care of COVID-19 patients, including intensive care wards. Aim of the study: The aim is assessing the impact of COVID-19 on cardiac imaging in Italy, compare to the Rest of Europe (RoE) and the World (RoW). Methods: A global survey was conducted in May–June 2020 worldwide, through a questionnaire distributed online. The survey covered three periods: March and April 2020, and March 2019. Data from 52 Italian centres, a subset of the 909 participating centres from 108 countries, were analyzed. Results: In Italy, volumes decreased by 67% in March 2020, compared to March 2019, as opposed to a significantly lower decrease (p &lt; 0.001) in RoE and RoW (41% and 40%, respectively). A further decrease from March 2020 to April 2020 summed up to 76% for the North, 77% for the Centre and 86% for the South. When compared to the RoE and RoW, this further decrease from March 2020 to April 2020 in Italy was significantly less (p = 0.005), most likely reflecting the earlier effects of the containment measures in Italy, taken earlier than anywhere else in the West. Conclusions: The COVID-19 pandemic massively hit Italy and caused a disruption of healthcare services, including cardiac imaging studies. This raises concern about the medium- and long-term consequences for the high number of patients who were denied timely diagnoses and the subsequent lifesaving therapies and procedures