In vivo characterization of brain ultrashort‐T<sub>2</sub> components

Boucneau, Tanguy; Cao, Peng; Tang, Shuyu; Han, Misung; Xu, Duan; Henry, Roland G.; Larson, Peder E. Z.

doi:10.1002/mrm.27037

Cited by 32 publications

(92 citation statements)

References 23 publications

(40 reference statements)

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“…For voxels with mixed short T 2 and long T 2 components, UTE‐MRF measures an apparent T 1 and T 2 from the overall signal. To resolve the MRF signal into long and short T 2 components, a multicomponent analysis method could be employed and modeled into dictionary …”

Section: Discussionmentioning

confidence: 99%

“…Magnetic resonance imaging (MRI) provides exquisite contrast in soft tissues. However, bone, tendon, meniscus, and myelin sheath tissues, which have short or ultrashort T 2 values (on the order of 1‐10 ms), are barely detectable in conventional MRI . Ultrashort echo time (UTE) and zero echo time imaging techniques have been used to detect these constituents .…”

Section: Introductionmentioning

confidence: 99%

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Ultrashort echo time magnetic resonance fingerprinting (UTE‐MRF) for simultaneous quantification of long and ultrashort T₂ tissues

Cao

et al. 2019

Magnetic Resonance in Med

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Purpose To demonstrate an ultrashort echo time magnetic resonance fingerprinting (UTE‐MRF) method that allows quantifying relaxation times for muscle and bone in the musculoskeletal system and generating bone enhanced images that mimic CT scans. Methods A fast imaging steady‐state free precession MRF sequence with half pulse excitation and half projection readout was designed to sample fast T2 decay signals. Varying echo time (TE) of a sinusoidal pattern was applied to enhance sensitivity for tissues with short and ultrashort T2 values. The performance of UTE‐MRF was evaluated via simulations, phantom, and in vivo experiments. Results A minimal TE of 0.05 ms was achieved. Simulations indicated the sinusoidal TE sampling increased T2 quantification accuracy in the cortical bone and tendon but had little impact on long T2 muscle quantifications. For the rubber phantom, the averaged relaxometries from UTE‐MRF (T1 = 162 ms and T2 = 1.07 ms) compared well with the gold standard (T1 = 190 ms and T2∗ = 1.03 ms). For the long T2 agarose phantom, the linear regression slope between UTE‐MRF and gold standard was 1.07 (R2 = 0.991) for T1 and 1.04 (R2 = 0.994) for T2. In vivo experiments showed the detection of the cortical bone (averaged T2 = 1.0 ms) and Achilles tendon (averaged T2 = 15 ms). Scalp structures from the bone enhanced image show high similarity with CT. Conclusion The UTE‐MRF with sinusoidal TEs can simultaneously quantify T1, T2, proton density, and B0 in long, short, even ultrashort T2 musculoskeletal structures. Bone enhanced images can be achieved in the brain with UTE‐MRF.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ultrashort echo time magnetic resonance fingerprinting (UTE‐MRF) for simultaneous quantification of long and ultrashort T₂ tissues

Cao

et al. 2019

Magnetic Resonance in Med

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“…A minimum phase Shinnar‐Le Roux radiofrequency pulse with a duration of 112 µs and bandwidth of 50 kHz was used for selective excitation. A single echo was acquired after each RF excitation for each TR, using real time randomization of the echo times to reduce the effects of eddy currents . The same radial k‐space trajectory was sampled at multiple echo times in a randomized order to minimize motion‐related artifacts .…”

Section: Methodsmentioning

confidence: 99%

“…At short echo times, short T 2 * (ST2) signals in the liver are detectable. Signal components with multiple exponentially decaying rates, with different off‐resonance frequencies relative to water, or with different T 1 relaxation rates may exist, as shown in previous studies in other tissues . To simplify the model in this preliminary study, we hypothesized that ST2 is 1) monoexponential signal decay and 2) on resonance with water.…”

Section: Theorymentioning

confidence: 95%

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Characterizing a short T₂* signal component in the liver using ultrashort TE chemical shift‐encoded MRI at 1.5T and 3.0T

Zhu

Hernando

Johnson

et al. 2019

Magnetic Resonance in Med

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Purpose Recent studies have suggested the presence of short‐T2* signals in the liver, which may confound chemical shift‐encoded (CSE) fat quantification when using short echo times (TEs). The purpose of this study was to characterize the liver signal at short echo times and to determine its impact on liver fat quantification. Methods An ultrashort echo time (UTE) chemical shift‐encoded MRI (CSE‐MRI) technique and a multicomponent reconstruction were developed to characterize short‐T2* liver signals. Subsequently, liver fat fraction was quantified using a short‐TE (first TE = 0.7 ms) and UTE CSE‐MRI acquisitions and compared with a standard CSE‐MRI (first TE = 1.2 ms). Results Short‐T2* signals were consistently observed in the liver of all healthy volunteers imaged at both 1.5T and 3.0T. At 3.0T, short‐T2* signal fractions of 9.6 ± 1.5%, 7.0 ± 1.7%, and 7.4 ± 1.7% with T2* of 0.23 ± 0.05 ms, 0.20 ± 0.05 ms, and 0.10 ± 0.02 ms were measured in healthy volunteers, patients with liver cirrhotic disease, and patients with hepatic steatosis (but no cirrhosis), respectively. For proton density fat fraction (PDFF) estimation, 1.7% (P < .01) and 3.4% (P < .01) biases were observed in subjects imaged using short‐TE CSE‐MRI and using UTE CSE‐MRI at 1.5T, respectively. The biases were reduced to 0.4% and −0.7%, respectively, by excluding short echoes less than 1 ms. A 3.2% bias (P < .01) was observed in subjects imaged using UTE CSE‐MRI at 3.0T, which was reduced to 0.1% by excluding short echoes <1 ms. Conclusions A liver short‐T2* signal component was consistently observed and was shown to confound liver fat quantification when short echo times were used with CSE‐MRI.

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Bone material analogues for PET/MRI phantoms

et al. 2020

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Purpose: To develop bone material analogues that can be used in construction of phantoms for simultaneous PET/MRI systems. Methods: Plaster was used as the basis for the bone material analogues tested in this study. It was mixed with varying concentrations of an iodinated CT contrast, a gadolinium-based MR contrast agent, and copper sulfate to modulate the attenuation properties and MRI properties (T1 and T2*). Attenuation was measured with CT and 68 Ge transmission scans, and MRI properties were measured with quantitative ultrashort echo time pulse sequences. A proof-of-concept skull was created by plaster casting. Results: Undoped plaster has a 511 keV attenuation coefficient (~0.14 cm À1 ) similar to cortical bone (0.10-0.15 cm À1 ), but slightly longer T1 (~500 ms) and T2* (~1.2 ms) MR parameters compared to bone (T1~300 ms, T2*~0.4 ms). Doping with the iodinated agent resulted in increased attenuation with minimal perturbation to the MR parameters. Doping with a gadolinium chelate greatly reduced T1 and T2*, resulting in extremely short T1 values when the target T2* values were reached, while the attenuation coefficient was unchanged. Doping with copper sulfate was more selective for T2* shortening and achieved comparable T1 and T2* values to bone (after 1 week of drying), while the attenuation coefficient was unchanged. Conclusions: Plaster doped with copper sulfate is a promising bone material analogue for a PET/ MRI phantom, mimicking the MR properties (T1 and T2*) and 511 keV attenuation coefficient of human cortical bone.

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In vivo characterization of brain ultrashort‐T₂ components

Cited by 32 publications

References 23 publications

Ultrashort echo time magnetic resonance fingerprinting (UTE‐MRF) for simultaneous quantification of long and ultrashort T₂ tissues

Ultrashort echo time magnetic resonance fingerprinting (UTE‐MRF) for simultaneous quantification of long and ultrashort T₂ tissues

Characterizing a short T₂* signal component in the liver using ultrashort TE chemical shift‐encoded MRI at 1.5T and 3.0T

Bone material analogues for PET/MRI phantoms

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In vivo characterization of brain ultrashort‐T2 components

Cited by 32 publications

References 23 publications

Ultrashort echo time magnetic resonance fingerprinting (UTE‐MRF) for simultaneous quantification of long and ultrashort T2 tissues

Ultrashort echo time magnetic resonance fingerprinting (UTE‐MRF) for simultaneous quantification of long and ultrashort T2 tissues

Characterizing a short T2* signal component in the liver using ultrashort TE chemical shift‐encoded MRI at 1.5T and 3.0T

Bone material analogues for PET/MRI phantoms

Contact Info

Product

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In vivo characterization of brain ultrashort‐T₂ components

Ultrashort echo time magnetic resonance fingerprinting (UTE‐MRF) for simultaneous quantification of long and ultrashort T₂ tissues

Ultrashort echo time magnetic resonance fingerprinting (UTE‐MRF) for simultaneous quantification of long and ultrashort T₂ tissues

Characterizing a short T₂* signal component in the liver using ultrashort TE chemical shift‐encoded MRI at 1.5T and 3.0T