Volume 79, Issue 1 pp. 515-528
Full Paper

A novel phase-unwrapping method based on pixel clustering and local surface fitting with application to Dixon water–fat MRI

Junying Cheng

Junying Cheng

School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu, China

Guangdong Provincial Key Laborary of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China

Search for more papers by this author
Yingjie Mei

Yingjie Mei

Guangdong Provincial Key Laborary of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China

Search for more papers by this author
Biaoshui Liu

Biaoshui Liu

Guangdong Provincial Key Laborary of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China

Search for more papers by this author
Jijing Guan

Jijing Guan

Guangdong Provincial Key Laborary of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China

Search for more papers by this author
Xiaoyun Liu

Xiaoyun Liu

School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu, China

Search for more papers by this author
Ed X. Wu

Ed X. Wu

Laboratory of Biomedical Imaging and Signal Processing, the University of Hong Kong, Hong Kong SAR, China

Department of Electrical and Electronic Engineering, the University of Hong Kong, Hong Kong SAR, China

Search for more papers by this author
Qianjin Feng

Qianjin Feng

Guangdong Provincial Key Laborary of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China

Search for more papers by this author
Wufan Chen

Corresponding Author

Wufan Chen

School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu, China

Guangdong Provincial Key Laborary of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China

Correspondence to: Yanqiu Feng, Ph.D., School of Biomedical Engineering, Southern Medical University, No. 1023 Shatai Nan Rd, Guangzhou, China 510515. Tel: + 86 20 6164 8294; Fax: + 86 20 6164 8274; E-mail: [email protected].Search for more papers by this author
Yanqiu Feng

Corresponding Author

Yanqiu Feng

Guangdong Provincial Key Laborary of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China

Correspondence to: Yanqiu Feng, Ph.D., School of Biomedical Engineering, Southern Medical University, No. 1023 Shatai Nan Rd, Guangzhou, China 510515. Tel: + 86 20 6164 8294; Fax: + 86 20 6164 8274; E-mail: [email protected].Search for more papers by this author
First published: 01 March 2017
Citations: 9

Correction added after online publication 03 April 2017. The authors updated the model of the MR Scanner from “XGR-OPER” to “XGY-OPER” in the In Vivo Data Acquisition section.

Abstract

Purpose

To develop and evaluate a novel 2D phase-unwrapping method that works robustly in the presence of severe noise, rapid phase changes, and disconnected regions.

Theory and Methods

The MR phase map usually varies rapidly in regions adjacent to wraps. In contrast, the phasors can vary slowly, especially in regions distant from tissue boundaries. Based on this observation, this paper develops a phase-unwrapping method by using a pixel clustering and local surface fitting (CLOSE) approach to exploit different local variation characteristics between the phase and phasor data. The CLOSE approach classifies pixels into easy-to-unwrap blocks and difficult-to-unwrap residual pixels first, and then sequentially performs intrablock, interblock, and residual-pixel phase unwrapping by a region-growing surface-fitting method. The CLOSE method was evaluated on simulation and in vivo water–fat Dixon data, and was compared with phase region expanding labeler for unwrapping discrete estimates (PRELUDE).

Results

In the simulation experiment, the mean error ratio by CLOSE was less than 1.50%, even in areas with signal-to-noise ratio equal to 0.5, phase changes larger than π, and disconnected regions. For 350 in vivo knee and ankle images, the water–fat swap ratio of CLOSE was 4.29%, whereas that of PRELUDE was 25.71%.

Conclusions

The CLOSE approach can correctly unwrap phase with high robustness, and benefit MRI applications that require phase unwrapping. Magn Reson Med 79:515–528, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.