Contributions
Abstract: P810
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - MRI and PET
Fluorine (19F) MR methods are currently not applied in clinical practice. However they could complement standard MR methods used in MS clinical studies. While 19F compounds can serve as contrast agents to study processes such as inflammation, some of the established 19F drugs used in MS (e.g. teriflunomide, siponimod) could be monitored by 19F MRI. We employ 19F MR methods in the experimental autoimmune encephalomyelitis (EAE) to study inflammation as well as the distribution of 19F drugs during disease progression. Although the absence of 19F background is an advantage for 19F MR, the low 19F availability in vivo poses a major challenge with respect to signal sensitivity. One way to overcome this is to enhance the signal or reduce the noise associated with MR measurements, in order to improve the signal-to-noise ratio (SNR). The SNR gain can then be exploited by increasing the level of detail when studying inflammation or improving the detection limit of 19F drugs, particularly when their availability e.g. in the brain is low. Here we present two of the approaches that we are using to improve SNR. The first approach makes use of a novel 19F cryogenic radio frequency probe (CRP) that increases SNR in the MR measurements by reducing noise (through cooling of the electronic components). The second approach makes use of higher magnetic field (B0) strengths; we have access to an MR scanner at the NHMFL with the highest B0 strength (21.1 Tesla). We studied both approaches to improve 19F SNR and image detail in inflammation. A dependency between 19F-MR relaxation and B0 was demonstrated; a reduction in longitudinal relaxation at 21.1T indicates a chance for increasing SNR via accelerated acquisitions. 19F-signals, not seen at 9.4T, were revealed in both mouse brain and lymph nodes at 21.1T. With the CRP approach, a detection limit in the order of 1015 19F atoms was reached, compared to 1016 fluorine atoms with another standard-coil used for 19F brain MRI (both at 9.4 T). The SNR gain achieved with the CRP was 1-15 depending on the proximity of the region of interest to the CRP. The SNR gain was also used to acquire high resolution 19F MRI of the EAE brain (150µm³) with the CRP, most signals were undetectable at this resolution when using the control coil. In conclusion, both approaches studied substantially improved 19F SNR and both could be employed in future in vivo studies to image 19F drugs in the brain or study neuroinflammation with greater detail.
Disclosure: Part of this work was performed at the US National High Magnetic Field Laboratory (NHMFL), which is supported by the State of Florida and the National Science Foundation Cooperative Agreement No. DMR-1157490.
SW: has received travel funding from the NHMFL User Collaborations Grant Program, research grants from Genzyme and Novartis, and presentation fees from Novartis.
JMM: has received presentation fees from Novartis.
CP: has received presentation fees from Genzyme and Novartis.
JTR: nothing to disclose.
LS: nothing to disclose.
AP: nothing to disclose.
HW: has received travel funding from the NHMFL User Collaborations Grant Program.
TN: is founder and CEO of MRI.TOOLS GmbH, chair of the Highfield and Applications study group of the International Society of Magnetic Resonance in Medicine, and has received travel funds from Siemens Healthcare.
Abstract: P810
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - MRI and PET
Fluorine (19F) MR methods are currently not applied in clinical practice. However they could complement standard MR methods used in MS clinical studies. While 19F compounds can serve as contrast agents to study processes such as inflammation, some of the established 19F drugs used in MS (e.g. teriflunomide, siponimod) could be monitored by 19F MRI. We employ 19F MR methods in the experimental autoimmune encephalomyelitis (EAE) to study inflammation as well as the distribution of 19F drugs during disease progression. Although the absence of 19F background is an advantage for 19F MR, the low 19F availability in vivo poses a major challenge with respect to signal sensitivity. One way to overcome this is to enhance the signal or reduce the noise associated with MR measurements, in order to improve the signal-to-noise ratio (SNR). The SNR gain can then be exploited by increasing the level of detail when studying inflammation or improving the detection limit of 19F drugs, particularly when their availability e.g. in the brain is low. Here we present two of the approaches that we are using to improve SNR. The first approach makes use of a novel 19F cryogenic radio frequency probe (CRP) that increases SNR in the MR measurements by reducing noise (through cooling of the electronic components). The second approach makes use of higher magnetic field (B0) strengths; we have access to an MR scanner at the NHMFL with the highest B0 strength (21.1 Tesla). We studied both approaches to improve 19F SNR and image detail in inflammation. A dependency between 19F-MR relaxation and B0 was demonstrated; a reduction in longitudinal relaxation at 21.1T indicates a chance for increasing SNR via accelerated acquisitions. 19F-signals, not seen at 9.4T, were revealed in both mouse brain and lymph nodes at 21.1T. With the CRP approach, a detection limit in the order of 1015 19F atoms was reached, compared to 1016 fluorine atoms with another standard-coil used for 19F brain MRI (both at 9.4 T). The SNR gain achieved with the CRP was 1-15 depending on the proximity of the region of interest to the CRP. The SNR gain was also used to acquire high resolution 19F MRI of the EAE brain (150µm³) with the CRP, most signals were undetectable at this resolution when using the control coil. In conclusion, both approaches studied substantially improved 19F SNR and both could be employed in future in vivo studies to image 19F drugs in the brain or study neuroinflammation with greater detail.
Disclosure: Part of this work was performed at the US National High Magnetic Field Laboratory (NHMFL), which is supported by the State of Florida and the National Science Foundation Cooperative Agreement No. DMR-1157490.
SW: has received travel funding from the NHMFL User Collaborations Grant Program, research grants from Genzyme and Novartis, and presentation fees from Novartis.
JMM: has received presentation fees from Novartis.
CP: has received presentation fees from Genzyme and Novartis.
JTR: nothing to disclose.
LS: nothing to disclose.
AP: nothing to disclose.
HW: has received travel funding from the NHMFL User Collaborations Grant Program.
TN: is founder and CEO of MRI.TOOLS GmbH, chair of the Highfield and Applications study group of the International Society of Magnetic Resonance in Medicine, and has received travel funds from Siemens Healthcare.