Intensity correction for multichannel hyperpolarized ¹³C imaging of the heart

Abstract

The analytical intensity correction scheme was shown to improve the uniformity of multichannel image reconstruction in hyperpolarized [1-(13) C]pyruvate and (13) C-bicarbonate cardiac MRI. The method is independent of the pulse sequence used for (13) C data acquisition, simple to implement and does not require additional scan time, making it an attractive technique for multichannel hyperpolarized (13) C MRI.

Translation of Carbon‐13 EPI for hyperpolarized MR molecular imaging of prostate and brain cancer patients

“…Although this variation is implicitly removed when computing the apparent rate constant or AUC ratio map, the individual dynamic images reflect the sensitivity profile of the 32‐channel array. This non‐uniform intensity could potentially be corrected using fiducial markers to analytically calculate the reception profile using the Biot‐Savart law, from coil sensitivity maps obtained from a thermal 13 C phantom, or from reception profiles extracted from the fully sampled hyperpolarized data using ESPIRiT . Improved coil combination methods could also be used to improve image quality over the conventional sum‐of‐squares approach used in this work.…”

Simultaneous multislice acquisition without trajectory modification for hyperpolarized 13C experiments

“…For phantom experiments, the ESPIRiT method was used to estimate coil sensitivities from low‐resolution images . For in vivo experiments, a low‐resolution reference scan would require using nonrecoverable magnetization; thus, numerical high‐resolution coil sensitivity estimates were calculated using the Biot‐Savart law using fiducial marker positioning as previously described …”

The use of hyperpolarized carbon-13 magnetic resonance for molecular imaging

“…Alternatively, a setup consisting of a volume transmit, surface receive coil can be used for homogenous power transmission [103]. Volume transmit/receive coils offer superior field homogeneity on both transmit/receive ends and, as such, are well suited for imaging the larger regions of interest typically used in abdominal and thoracic applications [110,111]. For small animal and perfused cell applications, cryocoils have shown to improve the SNR, although the degree of improvement is difficult to determine with certainty [111,112]; imaging researchers have reported SNR increases of 4–7 at 9.4T, consistent with theoretical considerations under low-loading conditions [111].…”

“…This approach requires accurate calibration of the coil’s RF power, which is typically done by placing a labeled 13 C phantom inside the coil next to the subject prior to administration of the hyperpolarized agent. Ideally, the coil’s B 1 map should also be obtained and incorporated into the reconstruction to improve image fidelity [110,114]. This is particularly important when single-channel receive surface coils or multichannel phased-array receive coils are used for parallel imaging.…”