Hyperpolarized Nuclei for NMR Imaging and Spectroscopy - Lunds ...

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22 250 RBC A (brain gray matter?) 200 205 150 200 B (brain white matter?) 195 ppm 100 ppm 190 C (?) Figure 4. Spectrum of hyperpolarized 129 Xe in the rat brain, acquired in our laboratory. The gas peak originates from signal picked up from the oral cavity. RBC = red blood cells. The assignment of peaks A, B, and C is still a matter of discussion (Ruppert et al. 2000a, Duhamel et al. 2001, Kilian 2001). Besides the aforementioned spectroscopy-based methods, attempts have been made to employ hyperpolarized noble gases in vascular applications. With respect to 3 He, this can only be accomplished by means of encapsulation, due to the insolubility of 3 He in blood and other fluids (see section 2.3.1). 3 He MR angiography (MRA) has been demonstrated in rats using microbubbles (Chawla et al. 1998, Callot et al. 2001) and microspheres (Chawla et al. 2000). When compared with microbubbles, microspheres are smaller and have a more uniform size distribution, which reduce the risk of pulmonary embolism. In both studies, 3 He concentrations of up to 7% per volume and T 1 of ∼1 min were achieved. The use of 129 Xe for vascular applications is hampered by low concentrations (∼1 mM when equilibrated with blood at atmospheric pressure) and the relatively short lifetime of the hyperpolarization in blood (T 1 ∼5 s (Wolber et al. 1999a)). Using a theoretical uptake model (Martin et al. 1997), it has been estimated that the SNR in brain gray matter could constitute ∼2% of the proton SNR under ideal conditions (50% Xe polarization, no signal loss during imaging) after inhalation of 80% Xe, and that the arterial SNR would be ∼10 times higher than the brain signal. Another model has estimated that the available signal after injection of dissolved Xe would not significantly exceed the signal attainable 50 185 gas 0
after gas inhalation, due to the wash-out of Xe when the bolus passes the lungs (Lavini et al. 2000). To improve the efficacy of injected 129 Xe, it has been suggested to inject “carrier agents,” in which 129 Xe has higher solubility and longer T 1 than in blood or saline (Wolber et al. 1999b, Venkatesh et al. 2000). Using a lipid emulsion (Intralipid, T 1 ∼25 s, T 2* ∼37 ms and Ostwald solubility coefficient ∼0.6, i.e., four times higher than in blood) as the carrier, angiograms of moderate quality (SNR ∼28) have been demonstrated in rats (Möller et al. 1999). A review of the possibilities to inject hyperpolarized noble gases has been presented by e.g., Goodson 1999. 2.6.3 Vascular imaging with hyperpolarized 13 C Hyperpolarized 13 C has only recently been available at polarization levels sufficient for MRI (Golman et al. 2001, Golman et al. 2002). At present, the polarization and T1 in vivo are comparable to those of 129 Xe in lipid emulsion (Möller et al. 1999). However, 13 C has the potential of being superior to the noble gases in vascular applications due to its availability as a hyperpolarized liquid, with in vivo concentrations about 2 orders of magnitude higher than those of 3 He and 129 Xe. Further, in the work of Svensson et al., the feasibility of hyperpolarized 13 C for MRA was investigated (Svensson 2002). 23
Page 1: ��
Page 4 and 5: DOKUMENTDATABLAD enl SIS 61 41 21 O
Page 6 and 7: Doctoral Dissertation Department of
Page 9 and 10: Abstract Based on the principle of
Page 11 and 12: Original papers This thesis is base
Page 13 and 14: Table of Contents 1 Introduction .
Page 15 and 16: 1 Introduction The phenomenon of nu
Page 17 and 18: By using hyperpolarized imaging age
Page 19 and 20: vector addition of all the magnetic
Page 21 and 22: illustrates the difference between
Page 23 and 24: pumping process (Colegrove and Fran
Page 25 and 26: thetic effects, and has been used a
Page 27 and 28: 1 T 1,O2 p = ξ O2 [11] where ξ Xe
Page 29 and 30: 1 2 2 −6 ∝ γC γHrτ c. [17] T
Page 31 and 32: and thus breaks down at very low fr
Page 33 and 34: 230 mT, e.g., Tseng et al. 1998, Du
Page 35: lation-perfusion ratio (V · A/Q ·
Page 39 and 40: tion of an NMR signal from a small
Page 41 and 42: larized gas with air took place as
Page 43 and 44: Table 5. Parameters of the imaging
Page 45 and 46: The images were evaluated with resp
Page 47 and 48: partial pressure present within the
Page 49 and 50: 3.8.2 Measurement procedure The spe
Page 51 and 52: 4.2 Vascular imaging of a 13 C-base
Page 53 and 54: gions. In central lung areas, regio
Page 55 and 56: 4.5 Diffusion capacity and perfusio
Page 57 and 58: 5 Discussion In this thesis, three
Page 59 and 60: due to the increased demand on the
Page 61 and 62: 5.3 Hyperpolarized 3 He ventilation
Page 63 and 64: a theoretical T 1 of ∼38 min in t
Page 65 and 66: eath-holding periods during, e.g.,
Page 67 and 68: 6 Conclusions The phantom study in
Page 69 and 70: 8 References ABRAGAM A, GOLDMAN M.
Page 71 and 72: CHEN XJ, MÖLLER HE, CHAWLA MS, COF
Page 73 and 74: GIERADA DS, SAAM B, YABLONSKIY D, C
Page 75 and 76: KAUCZOR HU, HANKE A, VAN BEEK EJ. A
Page 77 and 78: OLSSON LE, MAGNUSSON P, DENINGER AJ
Page 79 and 80: TILTON RF, JR., KUNTZ ID, JR. Nucle
Page 81: Paper I
Page 84 and 85: formance of the gradient system, si
Page 86 and 87:
S. MÅNSSON ET AL. Fig. 2. a-h) EPI
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though several technical issues rem
Page 91 and 92:
Hyperpolarized 13 C MR angiography
Page 93 and 94:
Introduction The most widespread te
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of the gradient moments prior to ea
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Methods Polarization procedure The
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secutive trueFISP images were acqui
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also to several other sources such
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low γ of 13 C reduces the sensitiv
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9. Chawla MS, Chen XJ, Möller HE,
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My 1 0.8 0.6 0.4 0.2 0 0 50 100 150
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Signal [a.u] 100 90 80 70 60 50 40
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a b Figure 5. Series of angiograms
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Paper III
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224 Deninger et al. FIG. 1. Sketch
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226 Deninger et al. FIG. 2. Coronal
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228 Deninger et al. FIG. 6. Histogr
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230 Deninger et al. FIG. 9. Monte C
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232 Deninger et al. 5. Gur D, Draye
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3 He MRI-based measurement of posit
Page 129 and 130:
Introduction It is well known that
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3 He imaging All experiments were p
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coefficients b 1 and b 2, respectiv
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Using VI data after subtraction of
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To investigate whether the calculat
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14. Gur D, Drayer BP, Borovetz HS,
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Table 1. Gradient of VI [cm −1 ]
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Cycle 1 Cycle 2 Cycle 3 Cycle 4 2 s
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a Prone Ventilation index c Supine
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a Prone Supine 0 b 1 R 2 Prone Supi
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Paper V
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Abstract The ability to quantify pu
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lation and perfusion information by
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Applying the conditions at the inne
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where L is obtained from Eq. [8]. V
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After tracheal intubation, the anim
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Parametric analysis The fit of the
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in the LPS-treated group is consist
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3. Worsley DF, Palevsky HI, Alavi A
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enin activity in rats chronically e
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V-20 blood without Xe C a V a (t) L
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V-22 Error in estimated diffusion l
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V-24 NMR Ventilator repetition loop
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Figure 7. The peak amplitudes (circ
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