Dataset Information

To measure T₁ of short T₂ species using an inversion recovery prepared three-dimensional ultrashort echo time (3D IR-UTE) method: A phantom study.

ABSTRACT:

Purpose

To demonstrate the feasibility of a new method for measuring T₁ of short T₂ species based on an adiabatic inversion recovery-prepared three-dimensional ultrashort echo time Cones (3D IR-UTE-Cones) sequence.

Methods

T₁ values for short T₂ species were quantified using 3D IR-UTE-Cones data acquired with different repetition times (TRs) and inversion times (TIs). An inversion efficiency factor Q was introduced into the fitting model to accurately calculate T₁ values for short T₂ species. Experiments were performed on twelve MnCl₂ aqueous solution phantoms with a wide range of T₁ values and T₂* values on a 3 T clinical MR system to verify the efficacy of the proposed method. For comparison, a variable flip angle UTE (VFA-UTE) sequence, a variable TR UTE (VTR-UTE) sequence, and a conventional 2D IR fast spin echo (IR-FSE) sequence were also used to quantify T₁ values of those phantoms. T₁ values were compared between all performed sequences.

Results

The proposed 3D IR-UTE-Cones method provided higher contrast images of short T₂ phantoms and measured much shorter T₁ values than the VFA-UTE, VTR-UTE and 2D IR-FSE methods. T₁ values as short as 2.95 ms could be measured by the 3D IR-UTE-Cones sequence. The 3D IR-UTE-Cones methods with different TRs were applied to different ranges of T₁ measurement, and the scan time was significantly decreased by using 5 TIs along the recovery curves to perform fitting with comparable accuracy.

Conclusion

The 3D IR-UTE-Cones sequence could accurately measure short T₁ values while providing high contrast images of short T₂ species.

SUBMITTER: Wei Z

PROVIDER: S-EPMC7307614 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Publications

To measure T<sub>1</sub> of short T<sub>2</sub> species using an inversion recovery prepared three-dimensional ultrashort echo time (3D IR-UTE) method: A phantom study.

Wei Zhao Z Ma Ya-Jun YJ Jang Hyungseok H Yang Wenhui W Du Jiang J

Journal of magnetic resonance (San Diego, Calif. : 1997) 20200413

<h4>Purpose</h4>To demonstrate the feasibility of a new method for measuring T<sub>1</sub> of short T<sub>2</sub> species based on an adiabatic inversion recovery-prepared three-dimensional ultrashort echo time Cones (3D IR-UTE-Cones) sequence.<h4>Methods</h4>T<sub>1</sub> values for short T<sub>2</sub> species were quantified using 3D IR-UTE-Cones data acquired with different repetition times (TRs) and inversion times (TIs). An inversion efficiency factor Q was introduced into the fitting model ...[more]

PMID: 32320926

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Project description:Background Signal contamination from long T2 water is a major challenge in direct imaging of myelin with MRI. Nulling of the unwanted long T2 signals can be achieved with an inversion recovery (IR) preparation pulse to null long T2 white matter within the brain. The remaining ultrashort T2 signal from myelin can be detected with an ultrashort echo time (UTE) sequence. Purpose To develop patient-specific whole-brain myelin imaging with a three-dimensional double-echo sliding inversion recovery (DESIRE) UTE sequence. Materials and Methods The DESIRE UTE sequence generates a series of IR images with different inversion times during a single scan. The optimal inversion time for nulling long T2 signal is determined by finding minimal signal on the second echo. Myelin images are generated by subtracting the second echo image from the first UTE image. To validate this method, a prospective study was performed in phantoms, cadaveric brain specimens, healthy volunteers, and patients with multiple sclerosis (MS). A total of 20 healthy volunteers (mean age, 40 years ± 13 [standard deviation], 10 women) and 20 patients with MS (mean age, 58 years ± 8; 15 women) who underwent MRI between November 2017 and February 2019 were prospectively included. Analysis of variance was performed to evaluate the signal difference between MS lesions and normal-appearing white matter in patients with MS. Results High signal intensity and corresponding T2* and T1 of the extracted myelin vesicles provided evidence for direct imaging of ultrashort-T2 myelin protons using the UTE sequence. Gadobenate dimeglumine phantoms with a wide range of T1 values were selectively suppressed with DESIRE UTE. In the ex vivo brain study of MS lesions, signal loss was observed in MS lesions and was conformed with histologic analysis. In the human study, there was a significant reduction in normalized signal intensity in MS lesions compared with that in normal-appearing white matter (0.19 ± 0.10 vs 0.76 ± 0.11, respectively; P < .001). Conclusion The double-echo sliding inversion recovery ultrashort echo time sequence can generate whole-brain myelin images specifically with a clinical 3-T scanner. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Port in this issue.

Project description:PurposeTo evaluate the relationship between delivered radiation (RT) and post-RT inversion-recovery ultrashort-echo-time (IR-UTE) MRI signal-intensity (SI) in gynecologic cancer patients treated with high-dose-rate (HDR) brachytherapy (BT).MethodsSeven patients underwent whole-pelvis RT (WPRT) followed by BT to the high-risk clinical target volume (HR-CTV). MR images were acquired at three time-points; pre-RT, post-WPRT/pre-BT, and 3-6 months post-BT. Diffuse-fibrosis (FDiffuse) was imaged with a non-contrast dual-echo IR (inversion time [TI] = 60 ms) UTE research application, with image-subtraction of the later echo, only retaining the ultrashort-echo SI. Dense-fibrosis (FDense) imaging utilized single-echo Late-Gadolinium-Enhanced IR-UTE, acquired ∼ 15 min post-Gadavist injection. Resulting FDiffuse and FDense SI were normalized to the corresponding gluteal-muscle SI. Images were deformably registered between time-points based on normal tissue anatomy. The remnant tumor at both time-points was segmented using multi-parametric MRI. Contours corresponding to the 50%, 100%, 150%, and 200% isodose lines (IDLs) of the prescription BT-dose were created. Mean FDiffuse and FDense SI within (i) each IDL contour and (ii) the remnant tumor were calculated. Post-BT FDiffuse and FDense SI were correlated with prescribed BT-dose. To determine the relationship between BT-dose and IR-UTE SI, the differences in the post-BT FDense across IDLs was determined using paired t-tests with Bonferroni correction.ResultsFDense was higher in regions of higher dose for 6/7 patients, with mean ± SD values of 357 ± 103% and 331 ± 97% (p = .03) in the 100% and 50% IDL, respectively. FDense was higher in regions of higher dose in the responsive regions with mean ± SD values of 380 ± 122% and 356 ± 135% (p = .03) in the 150% and 50% IDL, respectively. Within the segmented remnant tumor, an increase in prescribed dose correlated with an increase in FDense post-BT (n = 5, r = .89, p = .04). Post-BT FDiffuse inversely correlated (n = 7, r = -.83, p = .02) with prescribed BT-dose within the 100% IDL.ConclusionsResults suggest that FDense SI 3-6 months post-BT is a sensitive measure of tissue response to heterogeneous BT radiation-dose. Future studies will validate whether FDiffuse and FDense are accurate biomarkers of fibrotic radiation response.

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Dataset Information

To measure T₁ of short T₂ species using an inversion recovery prepared three-dimensional ultrashort echo time (3D IR-UTE) method: A phantom study.

Purpose

Methods

Results

Conclusion

Publications

To measure T<sub>1</sub> of short T<sub>2</sub> species using an inversion recovery prepared three-dimensional ultrashort echo time (3D IR-UTE) method: A phantom study.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

To measure T1 of short T2 species using an inversion recovery prepared three-dimensional ultrashort echo time (3D IR-UTE) method: A phantom study.

Purpose

Methods

Results

Conclusion

Publications

To measure T<sub>1</sub> of short T<sub>2</sub> species using an inversion recovery prepared three-dimensional ultrashort echo time (3D IR-UTE) method: A phantom study.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

To measure T₁ of short T₂ species using an inversion recovery prepared three-dimensional ultrashort echo time (3D IR-UTE) method: A phantom study.