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. 2016 Oct 7;3(1):e000149.
doi: 10.1136/bmjresp-2016-000149. eCollection 2016.

Assessment of Proximal Pulmonary Arterial Stiffness Using Magnetic Resonance Imaging: Effects of Technique, Age and Exercise

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Free PMC article

Assessment of Proximal Pulmonary Arterial Stiffness Using Magnetic Resonance Imaging: Effects of Technique, Age and Exercise

Jonathan R Weir-McCall et al. BMJ Open Respir Res. .
Free PMC article

Abstract

Introduction: To compare the reproducibility of pulmonary pulse wave velocity (PWV) techniques, and the effects of age and exercise on these.

Methods: 10 young healthy volunteers (YHV) and 20 older healthy volunteers (OHV) with no cardiac or lung condition were recruited. High temporal resolution phase contrast sequences were performed through the main pulmonary arteries (MPAs), right pulmonary arteries (RPAs) and left pulmonary arteries (LPAs), while high spatial resolution sequences were obtained through the MPA. YHV underwent 2 MRIs 6 months apart with the sequences repeated during exercise. OHV underwent an MRI scan with on-table repetition. PWV was calculated using the transit time (TT) and flow area techniques (QA). 3 methods for calculating QA PWV were compared.

Results: PWV did not differ between the two age groups (YHV 2.4±0.3/ms, OHV 2.9±0.2/ms, p=0.1). Using a high temporal resolution sequence through the RPA using the QA accounting for wave reflections yielded consistently better within-scan, interscan, intraobserver and interobserver reproducibility. Exercise did not result in a change in either TT PWV (mean (95% CI) of the differences: -0.42 (-1.2 to 0.4), p=0.24) or QA PWV (mean (95% CI) of the differences: 0.10 (-0.5 to 0.9), p=0.49) despite a significant rise in heart rate (65±2 to 87±3, p<0.0001), blood pressure (113/68 to 130/84, p<0.0001) and cardiac output (5.4±0.4 to 6.7±0.6 L/min, p=0.004).

Conclusions: QA PWV performed through the RPA using a high temporal resolution sequence accounting for wave reflections yields the most reproducible measurements of pulmonary PWV.

Keywords: Imaging/CT MRI etc.

Conflict of interest statement

Conflicts of Interest: None declared.

Figures

Figure 1
Figure 1
Transit time technique: (A) axial HASTE through the pulmonary trunk bifurcation; (B) short axis RPA; (C) short axis MPA; (D) short axis LPA; (E) flow curves from the three pulmonary arteries. Time delay between arrival of the three flow curves can then be derived, while the distance is measured from the axial HASTE image. HASTE, half-Fourier acquisition turbo spin echo; LPA, left pulmonary artery; MPA, main pulmonary artery; RPA, right pulmonary artery.
Figure 2
Figure 2
Assessment of the main pulmonary artery for calculation of the QA PWV. (A and C) demonstrate the magnitude and phase contrast images at the start of systole, while (B and D) demonstrate the magnitude and phase images at peak systolic flow. From these, the flow (E) and area (F) of the pulmonary artery is calculated, and then charted against each other (G), with the gradient of this line representing the PWV. QA, flow area; PWV, pulse wave velocity.
Figure 3
Figure 3
Bland-Altman plots comparing PWV repeatability during the same visit. The middle line represents the mean difference while the upper and lower lines represent the±2SD limit.3, three point technique; Inv, inverse squared reciprocal technique; LPA, left pulmonary artery; MPA, main pulmonary artery; PWV, pulse wave velocity; QA, flow area; RPA, right pulmonary artery; Trad, traditional technique; TT, transit time.
Figure 4
Figure 4
Bland-Altman plots comparing PWV repeatability on separate visits. The middle line represents the mean difference while the upper and lower lines represent the±2SD limit. 3, three point technique; Inv, inverse squared reciprocal technique; LPA, left pulmonary artery; MPA, main pulmonary artery; PWV, pulse wave velocity; QA, flow area; RPA, right pulmonary artery; Trad, traditional technique; TT, transit time.
Figure 5
Figure 5
Bland-Altman plots comparing intraobserver PWV repeatability. The middle line represents the mean difference while the upper and lower lines represent the±2SD limit. 3, three point technique; Inv, inverse squared reciprocal technique; LPA, left pulmonary artery; MPA, main pulmonary artery; PWV, pulse wave velocity; QA, flow area; RPA, right pulmonary artery; Trad, traditional technique; TT, transit time.
Figure 6
Figure 6
Bland-Altman plots comparing interobserver PWV repeatability. The middle line represents the mean difference while the upper and lower lines represent the±2SD limit. 3, three point technique; Inv, inverse squared reciprocal technique; LPA, left pulmonary artery; MPA, main pulmonary artery; PWV, pulse wave velocity; QA, flow area; RPA, right pulmonary artery; Trad, traditional technique; TT, transit time.

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