Dataset Information

A reproducible dynamic phantom for sequence testing in hyperpolarised ¹³C-magnetic resonance.

ABSTRACT:

Objective

To develop a phantom system which can be integrated with an automated injection system, eliminating the experimental variability that arises with manual injection; for the purposes of pulse sequence testing and metric derivation in hyperpolarised ¹³C-MR.

Methods

The custom dynamic phantom was machined from Ultem and filled with a nicotinamide adenine dinucleotide and lactate dehydrogenase mixture dissolved in phosphate buffered saline. Hyperpolarised [1-¹³C]-pyruvate was then injected into the phantom (n = 8) via an automated syringe pump and the conversion of pyruvate to lactate monitored through a ¹³C imaging sequence.

Results

The phantom showed low coefficient of variation for the lactate to pyruvate peak signal heights (11.6%) and dynamic area-under curve ratios (11.0%). The variance for the lactate dehydrogenase enzyme rate constant (kP) was also seen to be low at 15.6%.

Conclusion

The dynamic phantom demonstrates high reproducibility for quantification of ¹³C-hyperpolarised MR-derived metrics. Establishing such a phantom is needed to facilitate development of hyperpolarsed ¹³C-MR pulse sequenced; and moreover, to enable multisite hyperpolarised ¹³C-MR clinical trials where assessment of metric variability across sites is critical.

Advances in knowledge

The dynamic phantom developed during the course of this study will be a useful tool in testing new pulse sequences and standardisation in future hyperpolarised work.

SUBMITTER: Chowdhury R

PROVIDER: S-EPMC10996405 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Publications

A reproducible dynamic phantom for sequence testing in hyperpolarised <sup>13</sup>C-magnetic resonance.

Chowdhury Rafat R Papoutsaki Marianthi-Vasiliki MV Müller Christoph A CA Smith Lorna L Gong Fiona F Bullock Max M Rogers Harriet H Mathew Manju M Syer Tom T Singh Saurabh S Retter Adam A Caselton Lucy L Ryu Jung J Oliver-Taylor Aaron A Golay Xavier X Bainbridge Alan A Gadian David G DG Punwani Shonit S

The British journal of radiology 20220308 1134

<h4>Objective</h4>To develop a phantom system which can be integrated with an automated injection system, eliminating the experimental variability that arises with manual injection; for the purposes of pulse sequence testing and metric derivation in hyperpolarised <sup>13</sup>C-MR.<h4>Methods</h4>The custom dynamic phantom was machined from Ultem and filled with a nicotinamide adenine dinucleotide and lactate dehydrogenase mixture dissolved in phosphate buffered saline. Hyperpolarised [1-<sup>1 ...[more]

PMID: 35230136

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Project description:OBJECTIVES:To investigate the use of a fast dynamic hyperpolarised 129Xe ventilation magnetic resonance imaging (DXeV-MRI) method for detecting and quantifying delayed ventilation in patients with chronic obstructive pulmonary disease (COPD). METHODS:Three male participants (age range 31-43) with healthy lungs and 15 patients (M/F?=?12:3, age range?=?48-73) with COPD (stages II-IV) underwent spirometry tests, quantitative chest computed tomography (QCT), and DXeV-MRI at 1.5-Tesla. Regional delayed ventilation was captured by measuring the temporal signal change in each lung region of interest (ROI) in comparison to that in the trachea. In addition to its qualitative assessment through visual inspection by a clinical radiologist, delayed ventilation was quantitatively captured by calculating a covariance measurement of the lung ROI and trachea signals, and quantified using both the time delay, and the difference between the integrated areas covered by the signal-time curves of the two signals. RESULTS:Regional temporal ventilation, consistent with the expected physiological changes across a free breathing cycle, was demonstrated with DXeV-MRI in all patients. Delayed ventilation was observed in 13 of the 15 COPD patients and involved variable lung ROIs. This was in contrast to the control group, where no delayed ventilation was demonstrated (p =?0.0173). CONCLUSIONS:DXeV-MRI offers a non-invasive way of detecting and quantifying delayed ventilation in patients with COPD, and provides physiological information on regional pulmonary function during a full breathing cycle. KEY POINTS:• Dynamic xenon MRI allows for the non-invasive detection and measurement of delayed ventilation in COPD patients. • Dynamic xenon MRI during a free breathing cycle can provide unique information about pulmonary physiology and pulmonary disease pathophysiology. • With further validation, dynamic xenon MRI could offer a non-invasive way of measuring collateral ventilation which can then be used to guide lung volume reduction therapy (LVRT) for certain COPD patients.

Project description:Hyperpolarised [1-13C]pyruvate MRI (HP-13C-MRI) is an emerging metabolic imaging technique that has shown promise for evaluating prostate cancer (PCa) aggressiveness. Accurate tumour delineation on HP-13C-MRI is vital for quantitative assessment of the underlying tissue metabolism. However, there is no consensus on the optimum method for segmenting HP-13C-MRI, and whole-mount pathology (WMP) as the histopathological gold-standard is only available for surgical patients. Although proton MRI can be used for tumour delineation, this approach significantly underestimates tumour volume, and metabolic tumour segmentation based on HP-13C-MRI could provide an important functional metric of tumour volume. In this study, we quantified metabolism using HP-13C-MRI and segmentation approaches based on WMP maps, 1H-MRI-derived T2-weighted imaging (T2WI), and HP-13C-MRI-derived total carbon signal-to-noise ratio maps (TC-SNR) with an SNR threshold of 5.0. 13C-labelled pyruvate SNR, lactate SNR, TC-SNR, and the pyruvate-to-lactate exchange rate constant (kPL) were significantly higher when measured using the TC-SNR-guided approach, which also corresponded to a significantly higher tumour epithelial expression on RNAscope imaging of the enzyme catalysing pyruvate-to-lactate metabolism (lactate dehydrogenase (LDH)). However, linear regression and Bland-Altman analyses demonstrated a strong linear relationship between all three segmentation approaches, which correlated significantly with RNA-scope-derived epithelial LDH expression. These results suggest that standard-of-care T2WI and TC-SNR maps could be used as clinical reference tools for segmenting localised PCa on HP-13C-MRI in the absence of the WMP gold standard. The TC-SNR-guided approach could be used clinically to target biopsies towards highly glycolytic tumour areas and therefore to sample aggressive disease with higher precision. KEY POINTS: • T2WI- and TC-SNR-guided segmentations can be used in all PCa patients and do not explicitly require WMP maps. • Agreement between the three segmentation approaches is biologically validated by their strong relationship with epithelial LDH mRNA expression. • The TC-SNR-guided approach can potentially be used to identify occult disease on 1H-MRI and target the most glycolytically active regions.

Dataset Information

A reproducible dynamic phantom for sequence testing in hyperpolarised ¹³C-magnetic resonance.

Objective

Methods

Results

Conclusion

Advances in knowledge

Publications

A reproducible dynamic phantom for sequence testing in hyperpolarised <sup>13</sup>C-magnetic resonance.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

A reproducible dynamic phantom for sequence testing in hyperpolarised 13C-magnetic resonance.

Objective

Methods

Results

Conclusion

Advances in knowledge

Publications

A reproducible dynamic phantom for sequence testing in hyperpolarised <sup>13</sup>C-magnetic resonance.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

A reproducible dynamic phantom for sequence testing in hyperpolarised ¹³C-magnetic resonance.