Simultaneous multislice acquisition without trajectory modification for hyperpolarized ¹³C experiments

Abstract

PurposeTo investigate the feasibility of performing large FOV hyperpolarized 13C metabolic imaging using simultaneous multislice excitation.MethodsA spectral‐spatial multislice excitation pulse was constructed by cosine modulation and incorporated into a 13C spiral imaging sequence. Phantom and in vivo pig experiments were performed to test the feasibility of simultaneous multislice data acquisition and image reconstruction. In vivo cardiac‐gated images of hyperpolarized pyruvate, bicarbonate, and lactate were obtained at 1 × 1 × 1 cm3 resolution over a 48 × 48 × 24 cm3 FOV with 2‐fold acceleration in the slice direction. Sensitivity encoding was used for image reconstruction with both autocalibrated and numerically calculated coil sensitivities.ResultsSimultaneous multislice images obtained with 2‐fold acceleration were comparable to reference unaccelerated images. Retained SNR figures greater than 80% were achieved over the part of the image containing the heart.ConclusionThis method is anticipated to enable large FOV imaging studies using hyperpolarized 13C substrates, with an aim toward whole‐body exams that have to date been out of reach.

Coil combination methods for multi-channel hyperpolarized 13C imaging data from human studies

“…In the field of hyperpolarized 13 C MRI, a number of published clinical and pre-clinical studies have used phased arrays for spectroscopic and imaging applications 2,3,[19][20][21][22][23][24][25][26] , and the choice of coil combination techniques varied between them, sometimes unspecified by authors. Among these studies, the SOS algorithm remains the most widely used and simplest method for combining multichannel data, despite lacking optimal SNR and its failure to preserve phase information.…”

“…This analytical estimate of coil weights was shown to be an effective method of combining multichannel data, with only minor intrinsic limits of the Biot-Savart law, which neglects detailed factors such as coil loading and current distribution 22 . Lau et al 23 have also proposed using the ESPIRiT method to estimate coil sensitivity maps for natural abundance 13 C phantom imaging, and Park et al 2 have described using both the SOS algorithm and the hyperpolarized [1-13 C]pyruvate map to combine data for human brain imaging applications. Because coil combination methods were not the central focus of these studies, the specific advantages and disadvantages were not evaluated in depth.…”

Comprehensive Literature Review of Hyperpolarized Carbon-13 MRI: The Road to Clinical Application

“…Cardiac imaging protocols need to consider cardiac cycle timing, motion correction, distortion correction, etc. [ 52 , 53 ]. To date, only a few clinical studies have been performed on the heart covering initially normal hearts (n = 4) [ 5 ] and later hearts of patients with type 2 diabetes (T2MD = 5, HC = 5) [ 54 ].…”

Cardiac applications of hyperpolarised magnetic resonance

“…This approach, however, is susceptible to frequency errors, which again would correspond to errors in the delivered flip angle, potentially utilising the entirety of the magnetisation in the injected probe prematurely by errantly playing a high-flip angle pulse. Another 'unconventional' approach to RF pulse design for hyperpolarised imaging is the use of simultaneous multi-slice techniques to excite up to three slices simultaneously, reading out aliased images that can be reconstructed through the use of differing coil sensitivities, provided that the hardware used permits such approaches [218].…”