Johan M Edvinsson

University of Pennsylvania, Philadelphia, Pennsylvania, United States

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Publications (6)12.09 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Alveolar ventilation/perfusion ratio (VA/Q) is a key parameter in functional imaging of the lung. Herein, regional VA/Q was calculated from regional values of alveolar partial pressure of oxygen (PAO2) measured by hyperpolarized 3He gas MRI (HP 3He MRI). Yorkshire pigs (n = 7, mean weight = 25 kg) were paralyzed and maintained under isoflurane anesthesia. Animals were placed into a birdcage coil, then transferred to the bore of a 1.5 T MRI unit. Prior to imaging, animals were manually ventilated with room air for 5 min, then a 3He gas mixture was administered during breathhold and imaging performed. PAO2 was measured based on the decay rate of 3He signal. Subjects' blood gas concentrations were measured and these values and PAO2 values entered into a system of four equations with four unknowns. Calculated VA/Q values were analyzed by preparing frequency distributions for the entire lung and compared to VA/Q frequency distributions previously established in the literature as normal using other diagnostic techniques. Distributions were consistent with those in the literature, indicating that HP 3He MRI may be an accurate, quantitative, noninvasive, and nonradioactive method for acquiring VA/Q for small regions of the lung.
    Magnetic Resonance in Medicine 08/2004; 52(1):65-72. · 3.27 Impact Factor
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    ABSTRACT: Several radiological imaging modalities are available to assist with the clinical diagnosis of pulmonary embolism (PE). The most frequently used techniques-nuclear medicine ventilation-perfusion (VP) scan, computed tomography (CT), magnetic resonance angiography (MRA), and pulmonary angiography (PA)-all have literature-supported, substantial limitations with respect to timeliness and patient safety. Hyperpolarized 3He magnetic resonance gas distribution imaging (HP 3He MRI) recently has shown potential as a safer and faster alternative. In this study, we performed HP 3He MRI on a porcine model (N = 6) of simulated PE using selective occlusion balloon catheterization (N = 4) and nonselective aged autologous clot injection (N = 1). The technique was also performed on a normal pig and again after the animal was killed. Temporal depletion of regional HP 3He MRI signal intensity provided for a qualitative assessment of simulated PE (N = 4), and regional PAO2 (alveolar partial pressure of oxygen) was calculated in affected airspaces for a quantitative assessment of simulated PE (N = 1). The preliminary results suggest that HP (3)He MRI shows promise as a means of assessing regional pulmonary perfusion abnormalities in the porcine models of simulated PE that were used in this study.
    Magnetic Resonance in Medicine 03/2004; 51(2):291-8. · 3.27 Impact Factor
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    ABSTRACT: Atelectasis, the collapse of small airways, is a significant clinical problem. We use hyperpolarized (HP) 3He magnetic resonance imaging (MRI), or HP 3He MRI, to describe atelectasis in the normal Yorkshire pig, the pig with atelectasis, and the pig with re-expansion of atelectasis. We compare HP 3He MRI findings with depictions of atelectasis by proton MRI. During end-expiration in the anesthetized and paralyzed Yorkshire pig (n = 6), HP 3He gas produced by the optical pumping spin-exchange method, was delivered via an endotracheal tube. For two separate groups, atelectasis was either induced by Fogarty-catheter occlusion balloon inflation (n = 3), or lateral chest wall administration of sodium hydroxide (NaOH) (n = 3). MRI was performed at time zero, at 5, 9, 13, 15, and 19 minutes after atelectasis production, 30 minutes after balloon deflation, and 10 and 30 minutes after recruitment of atelectatic areas with increased tidal volumes and added positive end-expiratory pressure. High-resolution, cross-sectional MR images were procured, and comparison was made with the traditional proton MRI. Atelectatic areas by HP 3He MRI were easily distinguishable in both subject groups, and correlated with those located by proton MR. HP 3He MR images showed absence of ventilation, whereas proton MR images depicted dense, white areas. Re-expansion of atelectasis was well delineated by HP 3He MRI. HP 3He MRI may overcome many of the shortcomings of other well-established radiographic methods. HP 3He MRI is a novel, informative method for describing atelectasis and its re-expansion.
    Academic Radiology 12/2003; 10(11):1283-90. · 1.91 Impact Factor
  • Masaru Ishii, Johan M. Edvinsson, Aman Jalali, Rahim R. Rizi
    Otolaryngology Head and Neck Surgery 08/2003; 129(2). · 1.73 Impact Factor
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    ABSTRACT: The aim of this study was to test the effectiveness of laser-hyperpolarized helium 3 (3He) as a contrast agent for magnetic resonance (MR) imaging of porcine paranasal sinuses. Imaging experiments were conducted on the heads of four 50-kg Yorkshire pigs after open sinus surgery was performed. Paranasal sinus MR images were obtained with laser-polarized 3He gas produced through the spin-exchange method. The gas was delivered into the sinuses through two 14-gauge plastic catheters inserted in the nostrils. The 3He MR images were then compared with spatially correlated proton MR images. The porcine paranasal sinuses were adequately depicted by MR imaging with hyperpolarized 3He. The signal intensity of the paranasal sinuses on the 3He MR images was related to the size of the opening joining the sinuses to the nasal cavity and was clearly time dependent. Hyperpolarized 3He MR imaging may be particularly useful for identifying the anatomic configuration of the paranasal sinuses, as well as for assessing sinus aeration. Further study of the time-dependence of 3He signal intensity may help increase understanding of gas exchange in the sinuses.
    Academic Radiology 05/2003; 10(4):373-8. · 1.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Rationale and Objectives. Atelectasis, the collapse of small airways, is a significant clinical problem. We use hyperpolarized (HP) 3He magnetic resonance imaging (MRI), or HP 3He MRI, to describe atelectasis in the normal Yorkshire pig, the pig with atelectasis, and the pig with re-expansion of atelectasis. We compare HP 3He MRI findings with depictions of atelectasis by proton MRI.Materials and Methods. During end-expiration in the anesthetized and paralyzed Yorkshire pig (n = 6), HP 3He gas produced by the optical pumping spin-exchange method, was delivered via an endotracheal tube. For two separate groups, atelectasis was either induced by Fogarty-catheter occlusion balloon inflation (n = 3), or lateral chest wall administration of sodium hydroxide (NaOH) (n = 3). MRI was performed at time zero, at 5, 9, 13, 15, and 19 minutes after atelectasis production, 30 minutes after balloon deflation, and 10 and 30 minutes after recruitment of atelectatic areas with increased tidal volumes and added positive end-expiratory pressure. High-resolution, cross-sectional MR images were procured, and comparison was made with the traditional proton MRI.Results. Atelectatic areas by HP 3He MRI were easily distinguishable in both subject groups, and correlated with those located by proton MR. HP 3He MR images showed absence of ventilation, whereas proton MR images depicted dense, white areas. Re-expansion of atelectasis was well delineated by HP 3He MRI.Conclusion. HP 3He MRI may overcome many of the shortcomings of other well-established radiographic methods. HP 3He MRI is a novel, informative method for describing atelectasis and its re-expansion.
    Academic Radiology - ACAD RADIOL. 01/2003; 10(11):1283-1290.

Publication Stats

72 Citations
12.09 Total Impact Points

Institutions

  • 2003
    • University of Pennsylvania
      • Department of Radiology
      Philadelphia, Pennsylvania, United States
    • Harbor-UCLA Medical Center
      Torrance, California, United States