Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2019 Aug 27;9:12400. doi: 10.1038/s41598-019-48896-6

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© The Author(s) 2019

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

PMC Copyright notice

(a) Block diagram of the matched-filter pulse compression algorithm of IV-DPAR. The bandpass FD filter ensures that any frequency components outside the modulation bandwidth are eliminated during the signal-processing. Examples of IV-DPAR signal (from early-stage human plaque) in (b) amplitude, (c) unwrapped instantaneous phase, (d) phase-ISDV and (e) PFA channels. A total of 50 signals (N = 50) were obtained for this measurement point. By encoding statistical information of phase-ISDV on amplitude, the PFA channel showed dramatic improvement in SNR and FWHM axial resolution by approximately 135% and 37%, respectively, compared to the amplitude channel while utilizing the same raw data. FFT: Fast Fourier Transform, IFFT: Inverse Fast Fourier Transform, Z*: complex conjugate, Re: Real component of R, Im: Imaginary component of R, X: multiplication, σ: standard deviation, BP filter: Bandpass filter, Amp.: Amplitude, Phase-ISDV: Phase Inverse Standard Deviation, PFA: Phase-filtered Amplitude.