Samuel W. Fielden

A new method for the determination of aortic pulse wave velocity using cross-correlation on 2D PCMR velocity data

To evaluate the reproducibility of a new multisite axial pulse wave velocity (PWV) measurement technique that makes use of 2D PCMR data and cross‐correlation analysis.

Typical readout durations in spiral cine DENSE yield blurred images and underestimate cardiac strains at both 3.0 T and 1.5 T

INTRODUCTIONnDisplacement encoding with stimulated echoes (DENSE) is a phase contrast technique that encodes tissue displacement into phase images, which are typically processed into measures of cardiac function such as strains. For improved signal to noise ratio and spatiotemporal resolution, DENSE is often acquired with a spiral readout using an 11.1u202fms readout duration. However, long spiral readout durations are prone to blurring due to common phenomena such as off-resonance and T2* decay, which may alter the resulting quantifications of strain. We hypothesized that longer readout durations would reduce image quality and underestimate cardiac strains at both 3.0u202fT and 1.5u202fT and that using short readout durations could overcome these limitations.nnnMATERIAL AND METHODSnComputational simulations were performed to investigate the relationship between off-resonance and T2* decay, the spiral cine DENSE readout duration, and measured radial and circumferential strain. Five healthy participants subsequently underwent 2D spiral cine DENSE at both 3.0u202fT and 1.5u202fT with several different readout durations 11.1u202fms and shorter. Pearson correlations were used to assess the relationship between cardiac strains and the spiral readout duration.nnnRESULTSnSimulations demonstrated that long readout durations combined with off-resonance and T2* decay yield blurred images and underestimate strains. With the typical 11.1u202fms DENSE readout, blurring was present in the anterior and lateral left ventricular segments of participants and was markedly improved with shorter readout durations. Radial and circumferential strains from those segments were significantly correlated with the readout duration. Compared to the 1.9u202fms readout, the 11.1u202fms readout underestimated radial and circumferential strains in those segments at both field strengths by up to 19.6% and 1.5% (absolute), or 42% and 7% (relative), respectively.nnnCONCLUSIONSnBlurring is present in spiral cine DENSE images acquired at both 3.0u202fT and 1.5u202fT using the typical 11.1u202fms readout duration, which yielded substantially reduced radial strains and mildly reduced circumferential strains. Clinical studies using spiral cine DENSE should consider these limitations, while future technical advances may need to leverage accelerated techniques to improve the robustness and accuracy of the DENSE acquisition rather than focusing solely on reduced acquisition time.

Refocused turbo spin echo for non-contrast peripheral magnetic resonance angiography

To develop and assess a three‐dimensional refocused turbo spin‐echo (rTSE) sequence for generating peripheral angiograms. This sequence combines the rapid T2‐weighting of TSE and the better flow performance of the fully‐refocused gradients of balanced steady state free precession (bSSFP), along with bSSFP‐style phase alternation of refocusing radiofrequency (RF) pulses.