Rapid T₂ mapping of mouse heart using the carr–purcell–meiboom–gill sequence and compressed sensing reconstruction

Abstract

Purpose To develop and prove preliminary validation of a fast in vivo T2 mapping technique for mouse heart. Materials and Methods MRI experiments were performed on a 7T animal scanner. The standard Carr-Purcell-Meiboom-Gill (CPMG) sequence was modified to minimize the effect of stimulated echoes for accurate T2 quantification. The acquisition was further accelerated with the compressed sensing approach. The accuracy of the proposed method was first validated with both phantom experiments and numerical simulations. In vivo T2 measurement was performed on seven mice in a manganese-enhanced MRI study. Results In phantom studies, T2 values obtained with the modified CPMG sequence are in good agreement with the standard spin-echo method (P > 0.05). Numerical simulations further demonstrated that with the application of the compressed sensing approach, fast T2 quantification with a spatial resolution of 2.3 mm can be achieved at a high temporal resolution of one minute per slice. With the proposed technique, an average T2 value of 25 msec was observed for mouse heart at 7T and this number decreased significantly after manganese infusion (P < 0.001). Conclusion A rapid T2 mapping technique was developed and assessed, which allows accurate T2 quantification of mouse heart at a temporal resolution of one minute per slice.

Dysprosium-Modified Tobacco Mosaic Virus Nanoparticles for Ultra-High-Field Magnetic Resonance and Near-Infrared Fluorescence Imaging of Prostate Cancer

“…First, a multislice, T 2 weighted imaging sequence (RARE) was used to provide location information on the cells or tumor with the following parameters: 55 TE/TR = 24/3000 ms, RARE factor = 8, NAV = 1, 15 axial slices with 1.5 mm thickness, matrix size = 128 × 128, 30 × 30 mm field of view (FOV). Total acquisition time was 48 s. Next, a single slice, T 2 -mapping Carr–Purcell–Meiboom–Gill sequence was optimized to detect the boundary of the lesions at the xenograft site with the following parameters: 56 TE = 8, 16, 24...512 ms (64 echoes), TR = 1000 ms, NAV = 2, 1.5 mm thickness, matrix size = 128 × 128, 30 × 30 mm FOV. Total acquisition time was 4 min 16 s. After imaging, the cell samples were collected and sonicated at 30% power for 30 s in ice, and the total protein content was measured using the Quick Start Bradford Protein Assay with bovine serum albumin as standard (Biorad, Hercules, CA).…”

A rapid T1 mapping method for assessment of murine kidney viability using dynamic manganese‐enhanced magnetic resonance imaging

“…can be reduced to: where R 2 is equal to 1/T 2 . A slow infusion of MnCl 2 at low dose induces an approximately linear accumulation of Mn 2+ and increase in R 2 over time . If the post‐contrast kidney T 2 is still much larger than the effective TE, the M 0 image at a certain time point during MnCl 2 infusion can be linearly interpolated from two M 0 images acquired at baseline and post‐contrast, respectively.…”

“…To evaluate Mn 2+ ‐induced T 2 change, T 2 mapping was performed in all mice at baseline and post‐contrast using a modified Carr–Purcell–Meiboom–Gill sequence . In this method, variable crusher gradients were applied before and after the 180° pulses to minimize the stimulated echo effects, and the slice thickness of the 180° pulses were adjusted to 3 times of the excitation pulse to ensure a uniform refocusing across the imaging slice.…”

Polydopamine-decorated tobacco mosaic virus for photoacoustic/magnetic resonance bimodal imaging and photothermal cancer therapy

“…The in vitro MRI studies were carried out using a horizontal Biospec 7 T scanners (Bruker Inc., Billerica, MA, USA) equipped with a 3-cm birdcage 1 H coil (Bruker, Erlangen, Germany). First, a multi-slice, T 2 weighted imaging sequence (RARE) 54 was used to provide location information about the cells with the following parameters: TE/TR=24/3000 ms, RARE factor = 8, NAV = 1, number of axial slices = 15, slice thickness = 1.5 mm, matrix size = 128 × 128, 30 × 30 mm field of view (FOV). The total acquisition time was 48 s. Next, single-slice T 1 -mapping was performed using a saturation-recovery-look-locker (SRLL) sequence as previously described, and a spiral readout to accelerate acquisition.…”