Post-hoc standardisation of parametric T1 maps in cardiovascular magnetic resonance imaging: a proof-of-concept

BACKGROUND

In cardiovascular magnetic resonance imaging parametric T1 mapping lacks universally valid reference values. This limits its extensive use in the clinical routine. The aim of this work was the introduction of our self-developed Magnetic Resonance Imaging Software for Standardization (MARISSA) as a post-hoc standardisation approach.

METHODS

Our standardisation approach minimises the bias of confounding parameters (CPs) on the base of regression models. 214 healthy subjects with 814 parametric T1 maps were used for training those models on the CPs: age, gender, scanner and sequence. The training dataset included both sex, eleven different scanners and eight different sequences. The regression model type and four other adjustable standardisation parameters were optimised among 240 tested settings to achieve the lowest coefficient of variation, as measure for the inter-subject variability, in the mean T1 value across the healthy test datasets (HTE, N = 40, 156 T1 maps). The HTE were then compared to 135 patients with left ventricular hypertrophy including hypertrophic cardiomyopathy (HCM, N = 112, 121 T1 maps) and amyloidosis (AMY, N = 24, 24 T1 maps) after applying the best performing standardisation pipeline (BPSP) to evaluate the diagnostic accuracy.

FINDINGS

The BPSP reduced the COV of the HTE from 12.47% to 5.81%. Sensitivity and specificity reached 95.83% / 91.67% between HTE and AMY, 71.90% / 72.44% between HTE and HCM, and 87.50% / 98.35% between HCM and AMY.

INTERPRETATION

Regarding the BPSP, MARISSA enabled the comparability of T1 maps independently of CPs while keeping the discrimination of healthy and patient groups as found in literature.

FUNDING

This study was supported by the BMBF / DZHK.

"Death and Taxes": Why Financial Compensation for Research Participants is an Economic and Legal Risk

In the US, research payments are technically taxable income. This article argues that tax liability is a form of possible economic and legal risk of paid research participation. Findings are presented from empirical research on Phase I healthy volunteer trials. The article concludes by discussing the implications of these findings for the informed consent process, as well as for broader ethical issues in whether and how payments for research participation should be regulated.

The Association Between Blood Lead Levels and Coronary Artery Calcium Score Determined by Using Coronary Computed Tomography Angiography

BACKGROUND

Lead exposure is a known risk factor for cardiovascular disease (CVD), and coronary artery calcification (CAC) is a biomarker for diagnosing atherosclerotic CVD. This study investigated the association between blood lead level (BLL) and CAC using coronary computed tomography (CT) angiography.

METHODS

This study enrolled 2,189 participants from the general population with no history or symptoms of CVD. All participants underwent coronary CT angiography, health examination, and BLL testing. The association between coronary artery calcium score (CACS) and BLL was analyzed.

RESULTS

The arithmetic mean of BLL was 2.71 ± 1.26 μg/dL, and the geometric mean was 2.42 (1.64) μg/dL, ranging from 0.12 to 10.14 μg/dL. There was a statistically significant positive correlation between CACS and BLL (r = 0.073, P < 0.001). Mean BLLs among predefined CACS categories were as follows: absent grade (CACS = 0), 2.67 ± 1.23 μg/dL; minimal grade (> 0, < 10), 2.81 ± 1.25 μg/dL; mild grade (≥ 10, < 100), 2.74 ± 1.29 μg/dL; moderate grade (≥ 100, < 400), 2.88 ± 1.38 μg/dL; severe grade (≥ 400): 3.22 ± 1.68 μg/dL. The odds ratio for severe CAC was 1.242 in association with an 1 μg/dL increase in BLL (P = 0.042).

CONCLUSION

Using coronary CT angiography, we determined a positive correlation between BLL and CAC among participants without CVD from the general population. To reduce the burden of CVD, efforts and policies should be geared toward minimizing environmental lead exposure.

Willingness of Latinx and African Americans to Participate in Nontherapeutic Trials: It Depends on Who Runs the Research

Background

Inclusion of racial/ethnic minorities in cancer-related research remains inadequate, continuing to impact disparate health outcomes. Data regarding enrollment of racial/ethnic minorities in nontherapeutic, health-related research is sparse, and even less is known about enrollment of those with a double disparity of racial/ethnic minorities in rural settings.

Objective

To examine perspectives of Latinx and African American (AA) healthy volunteers from rural and urban settings in five southern US states and Puerto Rico regarding their trust in research and their willingness to participate in nontherapeutic research trials based on who conducts the research.

Methods

This study was conducted in 2013 in rural and urban communities across Alabama, Florida, Georgia, Mississippi, Louisiana, and Puerto Rico. A 38-item questionnaire based on the Tuskegee Legacy Project Questionnaire assessed willingness, motivators, and barriers to participation in nontherapeutic cancer-related research. The sample was segmented into four subgroups by urban/rural location and race/ethnicity.

Results

Of 553 participants (rural Latinx=151, urban Latinx=158, rural AA=122, urban AA=122), more than 90% had never been asked to participate in research, yet 75% of those asked agreed to participate. Most had positive views regarding health-related research. Trust in who conducted research varied by subgroup. Personal doctors and university hospitals were most trusted by all subgroups; for-profit and tobacco companies were least trusted. Both Latinx subgroups trusted pharmaceutical companies more than AAs; local hospitals and for-profit businesses were more trusted by AAs. Both rural subgroups trusted research by insurance companies more than their urban counterparts.

Conclusions

If asked, rural and urban AA and Latinx healthy volunteers were willing to participate in health-related research, with personal doctors and university hospitals considered the most trusted sources to encourage/conduct research.

Quantifying Lumbar Mobilization With Inertial Measurement Unit

OBJECTIVE

Lumbar mobilization is a standard intervention for the management of low back pain, yet ways to quantify lumbar mobilization are limited. An inertial measurement unit (IMU) is a small and inexpensive device that can be used to quantify lumbar mobilization. The objective of this study was to determine the validity and reliability of an IMU in measuring the amplitude of displacement of a clinician's hand movement during oscillatory lumbar mobilization.

METHODS

An IMU was secured on a clinician's hand during application of mobilization forces at the L4 segment of 16 healthy participants. The validity of the IMU was tested against common laboratory methods of measurements (force plate and motion capture system). The reliability of the IMU measurements was determined between 2 clinicians (inter-rater reliability) and between 2 sessions (intra-rater reliability) by calculating percent error of measurement (%e) and limits of agreement (LOA). The reliability was considered high when |%e| ≤ 10% and |LOA| ≤ 20%; moderate when |%e| 10% to 20% and |LOA| 21% to 40%; and non-acceptable when |%e| > 20% and |LOA| > 40%.

RESULTS

The IMU measurements had high correlation with the force plate measurements (r_s = 0.94) and high agreement with the motion capture system measurements (%e = 4%, LOA = -11% and 20%). Both the inter-rater reliability (%e = 6%, LOA = -25% and 37%) and the intrarater reliability (%e = -1%, LOA = -29% and 27%) of IMU measurements were moderate.

CONCLUSION

The IMU seems to be a valid device to measure the amplitude of a clinician's hand movement. The moderate reliability found in this study may not reflect poor reliability of the IMU as much as inconsistency in reapplication of lumbar mobilization.

Re-Establishing Brain Networks in Patients with ESRD after Successful Kidney Transplantation

BACKGROUND AND OBJECTIVES

Cognition in ESRD may be improved by kidney transplantation, but mechanisms are unclear. We explored patterns of resting-state networks with resting-state functional magnetic resonance imaging among patients with ESRD before and after kidney transplantation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Thirty-seven patients with ESRD scheduled for kidney transplantation and 22 age-, sex-, and education-matched healthy subjects underwent resting-state functional magnetic resonance imaging. Patients were imaged before and 1 and 6 months after kidney transplantation. Functional connectivity of seven resting-state subnetworks was evaluated: default mode network, dorsal attention network, central executive network, self-referential network, sensorimotor network, visual network, and auditory network. Mixed effects models tested associations of ESRD, kidney transplantation, and neuropsychological measurements with functional connectivity.

RESULTS

Compared with controls, pretransplant patients showed abnormal functional connectivity in six subnetworks. Compared with pretransplant patients, increased functional connectivity was observed in the default mode network, the dorsal attention network, the central executive network, the sensorimotor network, the auditory network, and the visual network 1 and 6 months after kidney transplantation (P=0.01). Six months after kidney transplantation, no significant difference in functional connectivity was observed for the dorsal attention network, the central executive network, the auditory network, or the visual network between patients and controls. Default mode network and sensorimotor network remained significantly different from those in controls when assessed 6 months after kidney transplantation. A relationship between functional connectivity and neuropsychological measurements was found in specific brain regions of some brain networks.

CONCLUSIONS

The recovery patterns of resting-state subnetworks vary after kidney transplantation. The dorsal attention network, the central executive network, the auditory network, and the visual network recovered to normal levels, whereas the default mode network and the sensorimotor network did not recover completely 6 months after kidney transplantation. Neural resting-state functional connectivity was lower among patients with ESRD compared with control subjects, but it significantly improved with kidney transplantation. Resting-state subnetworks exhibited variable recovery, in some cases to levels that were no longer significantly different from those of normal controls.

Comparison of the placebo effect between different non-penetrating acupuncture devices and real acupuncture in healthy subjects: a randomized clinical trial

Background

Several studies have used placebo acupuncture methods in recent years as a way for blinding therapeutic effect of acupuncture, however placebo method selection has not followed enough methodological criteria to the point of stabilishing a consensus of what should be the best method to be used. This study aimed to evaluate the effectiveness of three different placebo acupuncture methods for blinding applied in healthy subjects.

Methods

This study was approved by the Ethics Committee of the Federal University of Sergipe with the number 47193015.5.0000.5546 and all individuals participating in the study signed a free and informed consent. For this study, 321 healthy volunteers were randomly divided into seven groups using the abdominal point stomach (ST) 25 and seven groups using the lumbar point bladder (Bl) 52 for stimulation. For real acupuncture procedure, three different methods of placebo acupuncture plus a mix between real acupuncture and placebo applied in the same individual, totaling fourteen groups in this study. Outcome assessments were performed before and immediately after applying the technique. Investigator who assessed variables had no knowledgement about the method was applied. Identification, weight and height were measured before puncture by using. At the end, subjects were asked if they believed they were receiving real or placebo acupuncture.

Results

There was no significant difference between groups for the perception about the type o stimulation (wheter real or placebo puncture). Percentage of subjects who reported to have received real acupuncture in the abdominal point was 69.56% in real group, 86.95% in group Park Sham, 82.60% in needle + foam, 91.30% in insertion and removal, 78.26% in real + Park Sham, 86.36% in real + needle and foam, 86.95% in real + insertion and removal, and for the lumbar point was 86.36% in real group, 86.95% in group Park Sham, 69.56% in needle + foam, 72% in insertion and removal, 86.95% in real + Park Sham, 81.81% in real + needle and foam and 78.26% in real + insertion and removal.

Conclusion

All placebo acupuncture methods proposed in this study were equally effective for bliding the study participants using either abdominal or lumbar acupoints, and none of the placebo methods presented benefit compared to the other to be used in future clinical trials.

Ethics Committee

Federal University of Sergipe (UFS), number of approval: 47193015.5.0000.5546

Trial registration

ensaiosclinicos.gov.br RBR-3w2p32 Registered in 28th January 2016.

PH Measurements of the Brain Using Phosphorus Magnetic Resonance Spectroscopy ((31)PMRS) in Healthy Men - Comparison of Two Analysis Methods

Background

Intracellular pH provides information on homeostatic mechanisms in neurons and glial cells. The aim of this study was to define pH of the brain of male volunteers using phosphorus magnetic resonance spectroscopy (³¹PMRS) and to compare two methods of calculating this value.

Material/Methods

In this study, 35 healthy, young, male volunteers (mean age: 25 years) were examined by ³¹PMRS in 1.5 T MR system (Signa Excite, GE). The FID CSI (Free Induction Decay Chemical Shift Imaging) sequence was used with the following parameters: TR=4000 ms, FA=90°, NEX=2. Volume of interest (VOI) was selected depending on the size of the volunteers’ brain (11–14 cm³, mean 11.53 cm³). Raw data were analyzed using SAGE (GE) software.

Results

Based on the chemical shift of peaks in the ³¹PMRS spectrum, intracellular pH was calculated using two equations. In both methods the mean pH was slightly alkaline (7.07 and 7.08). Results were compared with a t-test. Significant difference (p<0.05) was found between these two methods.

Conclusions

The ³¹PMRS method enables non-invasive in vivo measurements of pH. The choice of the calculation method is crucial for computing this value. Comparing the results obtained by different teams can be done in a fully credible way only if the calculations were performed using the same formula.

Pain perception in healthy young men is modified by time-of-day and is modality dependent

OBJECTIVE

Several physiological processes exhibit 24-hour oscillations termed circadian rhythms. Despite numerous investigations on the circadian dynamics of pain perception, findings related to this issue remain inconsistent. This study aimed to assess the effect of time-of-day on multimodal experimental pain perception in healthy males, including "static" and "dynamic" quantitative sensory tests.

DESIGN

A random order tests were performed in the morning, afternoon and evening.

SUBJECTS

Forty-eight healthy males (25.9 ± 4.7 years old).

METHODS

Three different pain modalities i) mechanical (pain threshold, tolerance, and intensity), ii) heat (pain threshold and intensity), iii) cold (pain threshold measured in °C and in seconds and cold pain tolerance and intensity) utilizing nine "static" pain parameters, and two "dynamic" pain paradigms i) temporal summation and ii) conditioned pain modulation were assessed in each session.

RESULTS

Pain scores varied significantly in six pain parameters during the day. Specifically, lower pain scores were found in the morning for cold pain threshold (in seconds and in °C), cold pain intensity, cold pain tolerance, heat pain threshold and intensity. There were no significant diurnal differences in the mechanical evoked pain parameters or in either of the "dynamic" pain paradigms.

CONCLUSIONS

Thermal pain scores varies during the day and morning seems to be the time-of-day most insensitive to pain. Also, dynamic tests and the mechanical pain model are not appropriate for detecting diurnal variability in pain. The results of this study may be partially explained by a potential analgesic effect of some hormones known to have diurnal variation (e.g., melatonin and cortisol).

Reference equations for the six-minute walk distance in healthy korean adults, aged 22-59 years

Background

The six-minute walk test has been widely used in people with chronic cardiopulmonary disorders as an outcome assessment with regards to therapeutic or prognostic determinants. This study was undertaken to determine the six-minute walk distance (6MWD) in a sample of healthy Koreans and to create a reference equation. We also compared the 6MWD of our cohort with previously published equations.

Methods

Two hundred fifty-nine healthy subjects (95 males) aged 22-59 years performed two walking tests using a standardized protocol. 6MWD was defined as the greatest distance achieved from the two tests. The effect of anthropometrics on the 6MWD was also investigated.

Results

The average 6MWD was 598.5±57.92 m, with significantly longer distances by males (628.9±59.51 m) than females (580.9±47.80 m) (p<0.001). Age, height, weight, and body mass index were significantly correlated with 6MWD in univariate analysis. Stepwise multiple regression showed height to be single independent predictor of 6MWD (r²=0.205, p<0.001). The reference equations derived in Caucasian and North African populations tend to overestimate the distance walked by Korean subjects, while Asian equations underestimate it.

Conclusion

The average 6MWD in these Korean populations was 600 m. The regression equation revealed that individual's height was the most significant predictor of distance, explaining 20.5% of the distance variance.