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Ma YJ, Fan S, Shao H, Du J, Szeverenyi NM, Young IR, Bydder GM. Use of Multiplied, Added, Subtracted and/or FiTted Inversion Recovery (MASTIR) pulse sequences. Quant Imaging Med Surg 2020; 10:1334-1369. [PMID: 32550142 DOI: 10.21037/qims-20-568] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The group of Multiplied, Added, Subtracted and/or fiTted Inversion Recovery (MASTIR) pulse sequences in which usually two or more inversion recovery (IR) images of different types are combined is described, and uses for this type of sequence are outlined. IR sequences of different types can be multiplied, added, subtracted, and/or fitted together to produce variants of the MASTIR sequence. The sequences provide a range of options for increasing image contrast, demonstrating specific tissues and fluids of interest, and suppressing unwanted signals. A formalism using the concept of pulse sequences as tissue property filters is used to explain the signal, contrast and weighting of the pulse sequences with both univariate and multivariate filter models. Subtraction of one magnitude reconstructed IR image from another with a shorter TI can produce very high T1 dependent positive contrast from small increases in T1. The reverse subtracted IR sequence can provide high positive contrast enhancement with gadolinium chelates and iron deposition which decrease T1. Additional contrast to that arising from increases in T1 can be produced by supplementing this with contrast arising from concurrent increases in ρm and T2, as well as increases or decreases in diffusion using subtraction IR with echo subtraction and/or diffusion subtraction. Phase images may show 180º differences as a result of rotating into the transverse plane both positive and negative longitudinal magnetization. Phase images with contrast arising in this way, or other ways, can be multiplied by magnitude IR images to increase the contrast of the latter. Magnetization Transfer (MT) and susceptibility can be used with IR sequences to improve contrast. Selective images of white and brown adipose tissue lipid and water components can be produced using different TIs and in and out-of-phase TEs. Selective images of ultrashort and short T2 tissue components can be produced by nulling long T2 tissue components with an inversion pulse and subtraction of images with longer TEs from images with ultrashort TEs. The Double Echo Sliding IR (DESIRE) sequence provides images with a wide range of TIs from which it is possible to choose values of TI to achieve particular types of tissue and/or fluid contrast (e.g., for subtraction with different TIs, as described above, and for long T2 tissue signal nulling with UTE sequences). Unwanted tissue and fluid signals can be suppressed by addition and subtraction of phase-sensitive (ps) and magnitude reconstructed images. The sequence also offers options for synergistic use of the changes in blood and tissue ρm, T1, T2/T2*, D* and perfusion that can be seen with fMRI of the brain. In-vivo and ex-vivo illustrative examples of normal brain, cartilage, multiple sclerosis, Alzheimer's disease, and peripheral nerve imaged with different forms of the MASTIR sequence are included.
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Affiliation(s)
- Ya-Jun Ma
- Department of Radiology, University of California, San Diego, San Diego, CA, USA
| | - Shujuan Fan
- Department of Radiology, University of California, San Diego, San Diego, CA, USA
| | - Hongda Shao
- Department of Radiology, University of California, San Diego, San Diego, CA, USA
| | - Jiang Du
- Department of Radiology, University of California, San Diego, San Diego, CA, USA
| | | | - Ian R Young
- Formerly Department of Electrical Engineering, Imperial College, London, UK
| | - Graeme M Bydder
- Department of Radiology, University of California, San Diego, San Diego, CA, USA
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Aguirre-Reyes DF, Sotelo JA, Arab JP, Arrese M, Tejos R, Irarrazaval P, Tejos C, Uribe SA, Andia ME. Intrahepatic portal vein blood volume estimated by non-contrast magnetic resonance imaging for the assessment of portal hypertension. Magn Reson Imaging 2015; 33:970-7. [PMID: 26117696 DOI: 10.1016/j.mri.2015.06.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/21/2015] [Indexed: 12/31/2022]
Abstract
PURPOSE To investigate the feasibility of estimating the portal vein blood volume that flows into the intrahepatic volume (IHPVBV) in each cardiac cycle using non-contrast MR venography technique as a surrogate marker of portal hypertension (PH). MATERIALS AND METHODS Ten patients with chronic liver disease and clinical symptoms of PH (40% males, median age: 54.0, range: 44-73 years old) and ten healthy volunteers (80% males, median age: 54.0, range: 44-66 years old) were included in this study. A non-contrast Triple-Inversion-Recovery Arterial-Spin-Labeling (TIR-ASL) technique was used to quantify the IHPVBV in one and two cardiac cycles. Liver (LV) and spleen volumes (SV) were measured by manual segmentation from anatomical MR images as morphological markers of PH. All images were acquired in a 1.5T Philips Achieva MR scanner. RESULTS PH patients had larger SV (P=0.02) and lower liver-to-spleen ratio (P=0.02) compared with healthy volunteers. The median IHPVBV in healthy volunteers was 13.5cm(3) and 26.5cm(3) for one and two cardiac cycles respectively, whereas in PH patients a median volume of 3.1cm(3) and 9.0cm(3) was observed. When correcting by LV, the IHPVBV was significantly higher in healthy volunteers than PH patients for one and two cardiac cycles. The combination of morphological information (liver-to-spleen ratio) and functional information (IHPVBV/LV) can accurately identify the PH patients with a sensitivity of 90% and specificity of 100%. CONCLUSION Results show that the portal vein blood volume that flows into the intrahepatic volume in one and two cardiac cycles is significantly lower in PH patients than in healthy volunteers and can be quantified with non-contrast MRI techniques.
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Affiliation(s)
- Daniel F Aguirre-Reyes
- Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, 7820436, Chile; Electrical Engineering Department, School of Engineering, Pontificia Universidad Catolica de Chile, Santiago, 7820436, Chile; Computation Sciences and Electronic Department, Universidad Tecnica Particular de Loja, Ecuador, Loja 1101608, Ecuador.
| | - Julio A Sotelo
- Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, 7820436, Chile; Electrical Engineering Department, School of Engineering, Pontificia Universidad Catolica de Chile, Santiago, 7820436, Chile.
| | - Juan P Arab
- Gastroenterology Department, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, 8331150, Chile.
| | - Marco Arrese
- Gastroenterology Department, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, 8331150, Chile.
| | - Rodrigo Tejos
- Gastroenterology Department, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, 8331150, Chile.
| | - Pablo Irarrazaval
- Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, 7820436, Chile; Electrical Engineering Department, School of Engineering, Pontificia Universidad Catolica de Chile, Santiago, 7820436, Chile.
| | - Cristian Tejos
- Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, 7820436, Chile; Electrical Engineering Department, School of Engineering, Pontificia Universidad Catolica de Chile, Santiago, 7820436, Chile.
| | - Sergio A Uribe
- Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, 7820436, Chile; Radiology Department, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, 8331150, Chile.
| | - Marcelo E Andia
- Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, 7820436, Chile; Radiology Department, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, 8331150, Chile.
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Dong HZ, Worters PW, Wu HH, Ingle RR, Vasanawala SS, Nishimura DG. Noncontrast-enhanced renal angiography using multiple inversion recovery and alternating TR balanced steady-state free precession. Magn Reson Med 2012; 70:527-36. [PMID: 23172805 DOI: 10.1002/mrm.24480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 08/07/2012] [Accepted: 08/09/2012] [Indexed: 01/05/2023]
Abstract
Noncontrast-enhanced renal angiography techniques based on balanced steady-state free precession avoid external contrast agents, take advantage of high inherent blood signal from the T 2 / T 1 contrast mechanism, and have short steady-state free precession acquisition times. However, background suppression is limited; inflow times are inflexible; labeling region is difficult to define when tagging arterial flow; and scan times are long. To overcome these limitations, we propose the use of multiple inversion recovery preparatory pulses combined with alternating pulse repetition time balanced steady-state free precession to produce renal angiograms. Multiple inversion recovery uses selective spatial saturation followed by four nonselective inversion recovery pulses to concurrently null a wide range of background T 1 species while allowing for adjustable inflow times; alternating pulse repetition time steady-state free precession maintains vessel contrast and provides added fat suppression. The high level of suppression enables imaging in three-dimensional as well as projective two-dimensional formats, the latter of which has a scan time as short as one heartbeat. In vivo studies at 1.5 T demonstrate the superior vessel contrast of this technique.
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Affiliation(s)
- Hattie Z Dong
- Department of Electrical Engineering, Magnetic Resonance Systems Research Laboratory, Stanford University, Stanford, California, USA.
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