Detection of early cartilage damage: feasibility and potential of gagCEST imaging at 7T

Brinkhof, Sander; Nizak, Razmara; Khlebnikov, Vitaliy; Prompers, Jeanine J.; Klomp, Dennis W. J.; Saris, Daniël B.F.

doi:10.1007/s00330-017-5277-y

Cited by 43 publications

(44 citation statements)

References 31 publications

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“…GAG content can also be visualized by employing a gagCEST imaging protocol, as shown in earlier work . While the gagCEST signal can be contaminated by signals originating from other compounds or influenced by system imperfections, it can now be obtained in the same scan session as sodium; benefiting from both modalities.…”

Section: Discussionmentioning

confidence: 99%

“…21 GAG content can also be visualized by employing a gagCEST imaging protocol, as shown in earlier work. 12 While the gagCEST signal can be contaminated by signals originating from other compounds or influenced by system imperfections, it can now be obtained in the same scan session as sodium; benefiting from both modalities. The sodium MRI will be more specific but is hindered by lower spatial resolution, and the higher resolution of gagCEST can reveal heterogeneities in more detail.…”

Section: Figurementioning

confidence: 99%

“…Examples of such biochemical MRI methods include T2 mapping, [5][6][7] T1ρ mapping, 8,9 delayed gadolinium enhanced MRI of cartilage (dGEMRIC), 10,11 glycosaminoglycan chemical exchange saturation transfer (gagCEST) [12][13][14] and sodium imaging, [15][16][17] each probing one or more characteristics of articular cartilage. These techniques result in quantitative biomarkers which reflect the biochemical composition of articular cartilage and can assess early cartilage damage.…”

Section: Introductionmentioning

confidence: 99%

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Uncompromised MRI of knee cartilage while incorporating sensitive sodium MRI

Brinkhof

Haghnejad²,

Ito

et al. 2019

NMR in Biomedicine

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Sodium imaging is able to assess changes in ion content, linked to glycosaminoglycan content, which is important to guide orthopeadic procedures such as articular cartilage repair. Sodium imaging is ideally performed using double tuned RF coils, to combine high resolution morphological imaging with biochemical information from sodium imaging to assess ion content. The proton image quality of such coils is often harshly degraded, with up to 50% of SNR or severe acceleration loss as compared to single tuned coils. Reasons are that the number of proton receive channels often severely reduced and double tuning will degrade the intrinsic sensitivity of the RF coil on at least one of the nuclei. However, the aim of this work was to implement a double‐tuned sodium/proton knee coil setup without deterioration of the proton signal whilst being able to achieve acquisition of high SNR sodium images.A double‐tuned knee coil was constructed as a shielded birdcage optimized for sodium and compromised for proton. To exclude any compromise, the proton part of the birdcage is used for transmit only and interfaced to RF amplifiers that can fully mitigate the reduced efficiency. In addition, a 15 channel single tuned proton receiver coil was embedded within the double‐resonant birdcage to maintain optimal SNR and acceleration for proton imaging. To validate the efficiency of our coil, the designed coil was compared with the state‐of‐the‐art single‐tuned alternative at 7 T. B1+ corrected SNR maps were used to compare both coils on proton performance and g‐factor maps were used to compare both coils on acceleration possibilities. The newly constructed double‐tuned coil was shown to have comparable proton quality and acceleration possibilities to the single‐tuned alternative while also being able to acquire high SNR sodium images.

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Section: Discussionmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Uncompromised MRI of knee cartilage while incorporating sensitive sodium MRI

Brinkhof

Haghnejad²,

Ito

et al. 2019

NMR in Biomedicine

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“…We used MTR asym to evaluate the gagCEST effect. MTR asym is widely used, but other measures of the gagCEST effect also exist, as well as alternative methods for the correction of B 0 and B 1 inhomogeneity . It is possible that other methods may be beneficial in improving the sensitivity to CS‐C.…”

Section: Discussionmentioning

confidence: 99%

The role of cartilage glycosaminoglycan structure in gagCEST

et al. 2020

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Glycosaminoglycan (GAG) chemical exchange saturation transfer (gagCEST) is a potential method for cartilage quality assessment. The aim of this study was to investigate how the gagCEST effect depends on the types and molecular organization of GAG typically found in articular cartilage. gagCEST was performed on different concentrations of GAG in various forms: free chains of chondroitin sulfate (CS) of different types (-A and -C) and GAG bound to protein in aggregated and nonaggregated aggrecan extracted from calf articular cartilage. The measured magnetization transfer ratio asymmetry (MTR asym ) was compared with known GAG concentrations or GAG concentrations determined through biochemical analysis. The gagCEST effect was assessed through the linear regression coefficient with 95% confidence interval of MTR asym per GAG concentration. We observed a lower gagCEST effect in phantoms containing a mixture of CS-A and CS-C compared with phantoms containing mainly CS-A. The difference in response corresponds well to the difference in CS-A concentration. GAG bound in aggrecan from calf articular cartilage, where CS-A is assumed to be the major type of GAG, produed a similar gagCEST effect as that observed for free CS-A. The effect was also similar for aggregated (ie, bound to hyaluronic acid) and nonaggregated aggrecan. In conclusion, our results indicate that the aggrecan structure in itself does not impact the gagCEST effect, but that the effect is strongly dependent on GAG type. In phantoms, the current implementation of gagCEST is sensitive to CS-A while for CS-C, the main GAG component in mature human articular cartilage, the sensitivity is limited. This difference in gagCEST sensitivity between GAG types detected in phantoms is a strong motivation to also explore the possibility of a similar effect in vivo. K E Y W O R D S 7 T, articular cartilage, chondroitin sulfate, gagCEST, phantom Abbreviations used: CI, confidence interval; CS, chondroitin sulfate; GAG, glycosaminoglycan; gagCEST, glycosaminoglycan chemical exchange saturation transfer; MTR asym , magnetization transfer ratio asymmetry; OA, osteoarthritis; PBS, phosphate buffered saline. André Struglics and Jonas Svensson are joint last authors.

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“…In this issue of European Radiology Brinkhof et al use gagCEST at 7T in volunteers and patients before cartilage repair surgery to show its clinical feasibility [10]. This study is also a first step to establish this technique as an imaging biomarker.…”

Section: What Does the Current Study Tell Us About Gagcest?mentioning

confidence: 98%