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

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4 Results 4.1 Inves tigation of dissol ved 129 Xe f or MRA applications (Pa per I) The spectroscopic measurements of the dissolved 129 Xe signal relative to the gas signal yielded an Ostwald solubility coefficient (ratio between dissolved concentration and gas concentration) of 2.8 ± 0.3 after intense shaking of the syringes containing 129 Xe gas and ethanol. With only gentle shaking, the solubility was 1.6 ± 0.3, indicating that an equilibrium solution was not reached. The T 1 relaxation of dissolved 129 Xe was measured to 160 ± 11 s when oxygen had been expelled from the ethanol by bubbling with helium. Without helium bubbling, the measured T 1 relaxation time was reduced to 55 ± 10 s. The T 2 relaxation time was measured to 25 s. A series of 4 images of hyperpolarized 129 Xe in the flow phantom, acquired with the SE-EPI sequence, is shown in Figure 10. The maximum SNR of these images was measured to 74. The SNR in the EPI image of thermally polarized xenon was 3.8. After normalization with respect to polarization and concentration, the maximum SNR of the hyperpolarized EPI images was ∼75% of the thermally polarized image. 0 s 3 s 6 s 9 s Figure 10. EPI images showing a time series of flowing HP 129 Xe, acquired with an inter-image delay of 1.5 s (every second image shown). The acquisition time of each image was 44 ms. The flow direction is indicated in the third image. The mean flow velocity was 15 cm/s and the polarization level was estimated at 2%. 36 Out In
4.2 Vascular imaging of a 13 C-based imaging agent (Paper II) The T 1 relaxation time of the 13 C substance in water solution was estimated at 82 ± 6 s. The signal evolution in the 15 consecutive trueFISP images without phase-encoding gradients is shown in Figure 11 (data shown for the first 6 images only), demonstrating that the signal could be retained between images. From the signal decay in a corresponding series of images, but with activated phase-encoding gradients, the T 2 relaxation time was estimated at 18 s. Max echo amplitude [a.u.] 6000 5000 4000 3000 2000 1000 0 0 64 128 192 Echo number 256 320 384 Figure 11. Maximum echo amplitudes from a series of 15 consecutive trueFISP images without phase encoding (data shown for the first 6 images only). The images were acquired with a 180° flip angle and each image was started with a 90° preparation pulse and ended with a 90° flip-back pulse. Dashed lines separate the individual images. The investigation of the trueFISP sequence at different flip angles confirmed that the maximal signal was obtained at a flip angle of 180°. The corresponding measurement using a FLASH sequence yielded, at an optimal flip angle of ∼10°, a ninefold reduction in signal as compared with the maximum signal of the trueFISP sequence. In vivo trueFISP images are presented in Figure 12. In the image covering the abdomen and thorax (a), the vena cava, the heart, the lungs, the aortic arc including the branches of the carotid arteries, the abdominal aorta, and 37
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 and 36: lation-perfusion ratio (V · A/Q ·
Page 37 and 38: after gas inhalation, due to the wa
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: 3.8.2 Measurement procedure The spe
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
Page 88 and 89: though several technical issues rem
Page 91 and 92: Hyperpolarized 13 C MR angiography
Page 93 and 94: Introduction The most widespread te
Page 95 and 96: of the gradient moments prior to ea
Page 97 and 98: Methods Polarization procedure The
Page 99 and 100: secutive trueFISP images were acqui
Page 101 and 102:
also to several other sources such
Page 103 and 104:
low γ of 13 C reduces the sensitiv
Page 105 and 106:
9. Chawla MS, Chen XJ, Möller HE,
Page 107 and 108:
My 1 0.8 0.6 0.4 0.2 0 0 50 100 150
Page 109 and 110:
Signal [a.u] 100 90 80 70 60 50 40
Page 111 and 112:
a b Figure 5. Series of angiograms
Page 113:
Paper III
Page 116 and 117:
224 Deninger et al. FIG. 1. Sketch
Page 118 and 119:
226 Deninger et al. FIG. 2. Coronal
Page 120 and 121:
228 Deninger et al. FIG. 6. Histogr
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230 Deninger et al. FIG. 9. Monte C
Page 124 and 125:
232 Deninger et al. 5. Gur D, Draye
Page 127 and 128:
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
Page 160 and 161:
After tracheal intubation, the anim
Page 162 and 163:
Parametric analysis The fit of the
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in the LPS-treated group is consist
Page 166 and 167:
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
Page 172 and 173:
V-22 Error in estimated diffusion l
Page 174 and 175:
V-24 NMR Ventilator repetition loop
Page 176:
Figure 7. The peak amplitudes (circ
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