Quantitative magnetisation transfer imaging in glioma: preliminary results

Tozer, Daniel J.; Rees, Jeremy; Benton, Christopher E.; Waldman, Adam D.; Jäger, Hans Rolf; Tofts, Paul S.

doi:10.1002/nbm.1614

Cited by 19 publications

(19 citation statements)

References 24 publications

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“…ADC was higher in the tumor region, suggesting a lower cellularity compared with normal tissues. PSR was significantly lower in the tumor, which is consistent with a few previously reported observations that used different qMT acquisition methods . The k mf and k fm maps show clear contrast between GM and WM and higher values within the tumor, but the overall signal‐to‐noise ratios are much lower.…”

Section: Resultssupporting

confidence: 90%

Quantitative magnetization transfer imaging of rodent glioma using selective inversion recovery

et al. 2013

NMR Biomed.

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Magnetization transfer provides an indirect means to detect variations in macromolecular contents in biological tissues non-invasively, but so far, there have been only a few quantitative MT (qMT) studies reported in cancer, all of which used off-resonance pulsed saturation methods. This paper describes the first implementation of a different qMT approach, selective inversion recovery (SIR), for characterizing tumor in vivo using a rodent glioma model. The SIR method is an on-resonance method capable of fitting qMT parameters and T1 relaxation time simultaneously without mapping B0 and B1, which is very suitable for high field qMT measurements due to lower saturation absorption rate. The results show that the average pool size ratio (PSR, the macromolecular pool vs. the free water pool) in rat 9L glioma (5.7%) is significantly lower compared with normal rat gray matter (9.2%) and white matter (17.4%), which suggests PSR is potentially a sensitive imaging biomarker for assessing brain tumor. Despite being less robust, the estimated MT exchange rates also show clear differences from normal tissues (19.7 Hz for tumors vs 14.8 and 10.2 Hz for grey and white mater respectively). In addition, the influence of confounding effects, e.g. B1 inhomogeneity, on qMT parameter estimates is investigated with numerical simulations. These findings not only assist better understanding of the changes in the macromolecular contents of tumors, but also are important for interpreting other imaging contrasts such as chemical exchange saturation transfer (CEST) of tumors.

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Section: Resultssupporting

confidence: 90%

Quantitative magnetization transfer imaging of rodent glioma using selective inversion recovery

et al. 2013

NMR Biomed.

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“…wileyonlinelibrary.com/journal/nbm relaxation, consistent with extensive earlier literature and conventional explanations of lower relaxation rates in malignant and other rapidly growing tissues (19). The MT exchange rate k mf is significantly higher in tumors, consistent with previous reports (16)(17)(18). There is also a small increase in ADC, suggesting a lower cellularity in tumors.…”

Section: Resultssupporting

confidence: 90%

On the origins of chemical exchange saturation transfer (CEST) contrast in tumors at 9.4 T

et al. 2014

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Chemical exchange saturation transfer (CEST) provides an indirect means to detect exchangeable protons within tissues through their effects on the water signal. Previous studies have suggested that amide proton transfer (APT) imaging, a specific form of CEST, detects endogenous amide protons with a resonance frequency offset 3.5 ppm downfield from water, and thus may be sensitive to variations of mobile proteins/peptides in tumors. However, since CEST measurements are influenced by various confounding effects, such as spillover saturation, magnetization transfer (MT) and MT asymmetry, the mechanism or degree of increased APT signal in tumors are not certain. In addition to APT, nuclear Overhauser enhancement (NOE) effects upfield from water may also provide distinct information about tissue composition. In the current study, APT, NOE and several other magnetic resonance parameters were measured and compared comprehensively in order to elucidate the origins of APT and NOE contrasts in tumors at 9.4T. In addition to conventional CEST methods, a new intrinsic inverse metric was applied to correct for relaxation and other effects. After corrections for spillover, MT and T1 effects, corrected APT in tumors was found not significantly different from normal tissues, but corrected NOE effects in tumors showed significant decreases compared with normal tissues. Biochemical measurements verified that there is no significant enhancement of protein contents in the tumors studied, consistent with corrected APT measurements and previous literature while qMT data showed decreases in the fractions of immobile macromolecules in tumors. Our results may assist better understanding the contrast depicted by CEST imaging in tumors, and the development of improved APT and NOE measurements for cancer imaging.

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“…Tozer et al (40) reported reduced macromolecular pool fraction in human gliomas compared with normal-appearing white matter. Thus, given these previously published reports and the data presented here, future qMT-MRI studies designed to study the effects of various biophysical processes in breast cancer on PSR measurements are warranted.…”

Section: Discussionmentioning

confidence: 99%

Quantitative Magnetization Transfer Imaging of the Breast at 3.0 T: Reproducibility in Healthy Volunteers

et al. 2016

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Quantitative magnetization transfer magnetic resonance imaging provides a means for indirectly detecting changes in the macromolecular content of tissue noninvasively. A potential application is the diagnosis and assessment of treatment response in breast cancer; however, before quantitative magnetization transfer imaging can be reliably used in such settings, the technique’s reproducibility in healthy breast tissue must be established. Thus, this study aims to establish the reproducibility of the measurement of the macromolecular-to-free water proton pool size ratio (PSR) in healthy fibroglandular (FG) breast tissue. Thirteen women with no history of breast disease were scanned twice within a single scanning session, with repositioning between scans. Eleven women had appreciable FG tissue for test–retest measurements. Mean PSR values for the FG tissue ranged from 9.5% to 16.7%. The absolute value of the difference between 2 mean PSR measurements for each volunteer ranged from 0.1% to 2.1%. The 95% confidence interval for the mean difference was ±0.75%, and the repeatability value was 2.39%. These results indicate that the expected measurement variability would be ±0.75% for a cohort of a similar size and would be ±2.39% for an individual, suggesting that future studies of change in PSR in patients with breast cancer are feasible.

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Quantitative magnetisation transfer imaging in glioma: preliminary results

Cited by 19 publications

References 24 publications

Quantitative magnetization transfer imaging of rodent glioma using selective inversion recovery

Quantitative magnetization transfer imaging of rodent glioma using selective inversion recovery

On the origins of chemical exchange saturation transfer (CEST) contrast in tumors at 9.4 T

Quantitative Magnetization Transfer Imaging of the Breast at 3.0 T: Reproducibility in Healthy Volunteers

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