Self‐adapting multi‐peak water‐fat reconstruction for the removal of lipid artifacts in chemical exchange saturation transfer (CEST) imaging

Zhao, Yu; Xu, Yan; Zhang, Zhongshuai; Zhao, Weiwei; Liu, Zhenzhi; Li, Jianqi

doi:10.1002/mrm.27859

Cited by 13 publications

(16 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Neutral lipids have a very low concentration in brain (50), which exist in the form of lipid droplets as energy reserves in bio tissues and cannot produce CEST effects. Note that neutral lipids in tissues could generate artifacts in Z-spectrum, which need to be carefully removed in CEST imaging (63)(64)(65). The NOE(-3.5ppm) signals arise from the aliphatic chains of phospholipids.…”

Section: Discussionmentioning

confidence: 99%

Assignment of molecular origins of NOE signal at −3.5 ppm in the brain

Zhao

2023

Preprint

Self Cite

View full text Add to dashboard Cite

Purpose: Nuclear Overhauser Enhancement mediated saturation transfer effect, termed NOE(-3.5 ppm), is a major source of chemical exchange saturation transfer (CEST) MRI contrasts at 3.5 ppm in the brain. Previous phantom experiments have demonstrated that both proteins and lipids, two major components in tissues, have substantial contributions to NOE(-3.5 ppm) signals. Their relative contributions in tissues are informative for the interpretation of NOE(-3.5 ppm) contrasts that could provide potential imaging biomarkers for relevant diseases, which remain incompletely understood. Methods: Experiments on homogenates and supernatants of brain tissues collected from healthy rats, that could isolate proteins from lipids, were performed to evaluate the relative contribution of lipids to NOE(-3.5 ppm) signals. On the other hand, experiments on ghost membranes with varied pH, and reconstituted phospholipids with different chemical compositions were conducted to study the dependence of NOE(-3.5 ppm) on physiological conditions. Besides, CEST imaging on rat brains bearing 9L tumors and healthy rat brains was performed to analyze the causes of the NOE(-3.5 ppm) contrast variations between tumors and normal tissues, and between gray matter and white matter. Results: Our experiments reveal that lipids have dominant contributions to the NOE (-3.5 ppm) signals. Further analysis suggests that decreased NOE(-3.5 ppm) signals in tumors and higher NOE(-3.5 ppm) signals in white matter than in gray matter are mainly explained by changes in membrane lipids, rather than proteins. Conclusion: NOE(-3.5 ppm) could be exploited as a highly sensitive MRI contrast for imaging membrane lipids in the brain.

show abstract

Section: Discussionmentioning

confidence: 99%

Assignment of molecular origins of NOE signal at −3.5 ppm in the brain

Zhao

2023

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Several methods have been proposed to suppress strong lipid artifacts in breast CEST imaging. [145][146][147] Fortunately, it has been shown that the standard spectral pre-saturation inversion-recovery (SPIR) method is generally sufficient for lipid artifact removal in APTw imaging of the brain. 148,149…”

Section: Lipid Suppressionmentioning

confidence: 99%

“…Zhu et al 122 demonstrated that lipid suppression can be effectively achieved using chemical‐shift selective removal before acquisition with an asymmetric, frequency‐modulated, lipid suppression pulse, followed by a crusher gradient. Several methods have been proposed to suppress strong lipid artifacts in breast CEST imaging 145–147 . Fortunately, it has been shown that the standard spectral pre‐saturation inversion‐recovery (SPIR) method is generally sufficient for lipid artifact removal in APTw imaging of the brain 148,149 …”

Section: Pulse Sequencesmentioning

confidence: 99%

Review and consensus recommendations on clinical APT‐weighted imaging approaches at 3T: Application to brain tumors

Zhou

Zaiß

Knutsson

et al. 2022

Magnetic Resonance in Med

119

138

View full text Add to dashboard Cite

Amide proton transfer-weighted (APTw) MR imaging shows promise as a biomarker of brain tumor status. Currently used APTw MRI pulse sequences and protocols vary substantially among different institutes, and there are no agreed-on standards in the imaging community. Therefore, the results acquired from different research centers are difficult to compare, which hampers uniform clinical application and interpretation. This paper reviews current clinical APTw imaging approaches and provides a rationale for optimized APTw brain tumor imaging at 3 T, including specific recommendations for pulse sequences, acquisition protocols, and data processing methods. We expect that these consensus recommendations will become the first broadly accepted guidelines for APTw imaging of brain tumors on 3 T MRI systems from different vendors. This will allow more medical centers to use the same or comparable APTw MRI techniques for the detection, characterization, and monitoring of brain tumors, enabling multi-center trials in larger patient cohorts and, ultimately, routine clinical use. K E Y W O R D APTw standardization, APT-weighted imaging, brain tumor, CEST imaging How to cite this article: Zhou J, Zaiss M, Knutsson L, et al. Review and consensus recommendations on clinical APT-weighted imaging approaches at 3T: Application to brain tumors.

show abstract

“…However, the DSP-CEST signals need to be corrected by mapping the B 0 inhomogeneity along with the B 0 inhomogeneity when the proposed method is applied to the human studies, considering the B 1 field could have substantial deviations in the ranges demonstrated in Fig. 4E-4H (57,58).…”

Section: Resultsmentioning

confidence: 99%

A new method for quantifying APT and NOE(-3.5) using chemical exchange saturation transfer with double saturation powers (DSP-CEST)

Zhao

Sun

2022

Preprint

Self Cite

View full text Add to dashboard Cite

Purpose: Quantifications of amide proton transfer (APT) and nuclear Overhauser enhancement (NOE(-3.5)) mediated transfer with high specificity are challenging since their signals measured in a Z-spectrum are overlapped with confounding signals from direct water saturation (DS), semi-solid magnetization transfer (MT) and chemical exchange saturation transfer (CEST) of fast-exchange pools. In this study, based on two canonical CEST acquisitions with double saturation powers (DSP), a new data-postprocessing method is proposed to specifically quantify the effects of APT and NOE. Methods: For CEST imaging with relatively low saturation powers (ω_1^2), both the fast-exchange CEST effect and the semi-solid MT effect increase linearly with ω_1^2 whereas the slow-exchange APT/NOE(-3.5) effect has no such a dependence on ω_1^2, which is exploited to isolate the APT and NOE effects from the confounding signals in this study. After a mathematical derivation for the establishment of the proposed method, numerical simulations based on Bloch equations are then performed to demonstrate its specificity to detections of the APT and NOE effects. Finally, an in vivo validation of the proposed method is conducted using an animal tumor model at a 4.7-T MRI scanner. Results: The simulations show that DSP-CEST can quantify the effects of APT and NOE and substantially eliminate the confounding signals. The in vivo experiments demonstrate that the prosed DSP-CEST method is feasible for the imaging of tumors. Conclusion: The data-postprocessing method proposed in this study can quantify the APT and NOE effects with considerably increased specificities and a reduced cost of imaging time.

show abstract

Self‐adapting multi‐peak water‐fat reconstruction for the removal of lipid artifacts in chemical exchange saturation transfer (CEST) imaging

Cited by 13 publications

References 62 publications

Assignment of molecular origins of NOE signal at −3.5 ppm in the brain

Assignment of molecular origins of NOE signal at −3.5 ppm in the brain

Review and consensus recommendations on clinical APT‐weighted imaging approaches at 3T: Application to brain tumors

A new method for quantifying APT and NOE(-3.5) using chemical exchange saturation transfer with double saturation powers (DSP-CEST)

Contact Info

Product

Resources

About