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Assessment of a novel 32-channel phased array for cardiovascular hybrid PET/MRI imaging: MRI performance
Adam Farag1,2, R Terry Thompson1,2, Jonathan D Thiessen1,2,3
1Lawson Health Research Institute, Imaging Division, 268 Grosvenor St., Rm E5-118, PO Box 5777, STN B, London, ON N6A 4V2 Canada.
Background:
Cardiovascular imaging using hybrid positron emission tomography (PET) and magnetic resonance imaging (MRI) requires a radio frequency phased array resonator capable of high acceleration factors in order to achieve the shortest breath-holds while maintaining optimal MRI signal-to-noise ratio (SNR) and minimum PET photon attenuation. To our knowledge, the only two arrays used today for hybrid PET/MRI cardiovascular imaging are either incapable of achieving high acceleration or affect the PET photon count greatly.
Purpose:
This study is focused on the evaluation of the MRI performance of a novel third-party prototype 32-channel phased array designed for simultaneous PET/MRI cardiovascular imaging. The study compares the quality parameters of MRI parallel imaging, such as g-factor, noise correlation coefficients, and SNR, to the conventional arrays (mMR 12-channel and MRI-only 32-channel) currently used with hybrid PET/MRI systems. The quality parameters of parallel imaging were estimated for multiple acceleration factors on a phantom and three healthy volunteers. Using a Germanium-68 (Ge-68) phantom, preliminary measurements of PET photon attenuation caused by the novel array were briefly compared to the photon counts produced from no-array measurements.
Results:
The global mean of the g-factor and SNRg produced by the novel 32-channel PET/MRI array were better than those produced by the MRI-only 32-channel array by 5% or more. The novel array has resulted in MRI SNR improvements of > 30% at all acceleration factors, in comparison to the mMR12-channel array. Preliminary evaluation of PET transparency showed less than 5% photon attenuation caused by both anterior and posterior parts of the novel array.
Conclusions:
The MRI performance of the novel PET/MRI 32-channel array qualifies it to be a viable alternative to the conventional arrays for cardiovascular hybrid PET/MRI. A detailed evaluation of the novel array's PET performance remains to be conducted, but cursory assessment promises significantly reduced attenuation.
Insights
A new 32-channel PET/MRI array offers improved MRI performance for cardiovascular imaging. This novel array enhances signal-to-noise ratio and shows minimal PET photon attenuation, making it a promising alternative for hybrid PET/MRI systems.
Area of Science:
- Medical Imaging
- Cardiovascular Imaging
- Hybrid PET/MRI Technology
Background:
- Hybrid positron emission tomography (PET) and magnetic resonance imaging (MRI) for cardiovascular imaging require specialized radio frequency phased array resonators.
- Existing resonators often struggle to balance high acceleration factors for shorter breath-holds with optimal MRI signal-to-noise ratio (SNR) and minimal PET photon attenuation.
- Current hybrid PET/MRI systems predominantly use arrays that are either slow or significantly impact PET photon counts.
Purpose of the Study:
- To evaluate the MRI performance of a novel prototype 32-channel phased array designed for simultaneous PET/MRI cardiovascular imaging.
- To compare key MRI parallel imaging quality parameters (g-factor, noise correlation, SNR) against conventional arrays (mMR 12-channel, MRI-only 32-channel).
- To conduct preliminary assessments of PET photon attenuation caused by the novel array using a Germanium-68 (Ge-68) phantom.
Main Methods:
- Assessed MRI parallel imaging quality parameters (g-factor, noise correlation coefficients, SNR) for the novel 32-channel array across multiple acceleration factors.
- Compared these parameters against established mMR 12-channel and MRI-only 32-channel arrays.
- Evaluated PET photon attenuation using a Ge-68 phantom and compared it to measurements without the array.
Main Results:
- The novel 32-channel PET/MRI array demonstrated a >5% improvement in global mean g-factor and SNRg compared to the MRI-only 32-channel array.
- MRI SNR improvements exceeding 30% were observed with the novel array at all acceleration factors relative to the mMR 12-channel array.
- Preliminary PET transparency tests indicated less than 5% photon attenuation from the novel array's components.
Conclusions:
- The novel 32-channel PET/MRI array exhibits superior MRI performance, positioning it as a viable alternative for cardiovascular hybrid PET/MRI applications.
- The array shows promise for significantly reduced PET photon attenuation, although further detailed PET performance evaluation is warranted.
- This development addresses key limitations of current systems, potentially enabling faster and more accurate hybrid cardiovascular imaging.
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