Eldrid H Winther-Larssen

Publications (4)8.35 Total impact

• Source

  Available from: Charlotte de Lange

  Article: A piglet model for detection of hypoxic-ischemic brain injury with magnetic resonance imaging.

  Berit Holthe Munkeby, Charlotte De Lange, Kyrre Eeg Emblem, Atle Bjørnerud, Grete A B Kro, Jannicke Andresen, Eldrid H Winther-Larssen, Else Marit Løberg, John K Hald
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  ABSTRACT: BACKGROUND: Early detection of hypoxic-ischemic (HI) injury in the asphyxic newborn is important because present prognostic factors are inadequate. Furthermore, therapeutic interventions may have additional benefit if initiated in time. PURPOSE: To assess whether the use of a combined protocol including conventional magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), and proton MR spectroscopy (MRS) could detect pathological findings in a piglet model 7 hours after HI. MATERIAL AND METHODS: Ten piglets were submitted to HI for 30 min followed by reoxygenation with 21% O2 for 7 hours. MRI at 1.5T was done prior to and 7 hours after the HI. Single-voxel proton MRS was performed, and apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured in the basal ganglia. MRS identified N-acetylaspartate (NAA), choline (Cho), creatine (Cr), and lactate (Lac). Histology and microtubule-associated protein 2 (MAP-2) staining was performed in the basal ganglia at the end of the experiment. RESULTS: Compared to baseline, ADC, NAA/Cho, and NAA/Cr were significantly reduced after 7 hours (P<0.001, P=0.01, and P=0.05, respectively) and FA values were increased (P<0.025). The ratios of Lac/Cho and Lac/NAA were significantly higher after 7 hours compared to baseline (P<0.001). Presence of necrosis correlated well with reduced ADC (R(S)=0.91) and presence of Lac (R(S)=0.80). Histology and MAP-2 staining showed more than 90% necrosis in eight piglets, 60% in one piglet, and no necrosis in one piglet. CONCLUSION: Diffusion MRI and proton MRS can detect HI injury in the piglet brain 7 hours after hypoxia. DWI and MRS can be used to give useful prognostic information. This piglet model may potentially be used to mimic clinical situations and is suitable for further research investigating HI injury.
  07/2009;
• Article: Magnetic resonance imaging of the Harderian gland in piglets.

  Berit H Munkeby, Hans-Jørgen Smith, Eldrid H Winther-Larssen, Atle Bjørnerud, Inge Bjerkås
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  ABSTRACT: The main purpose of the present study was to investigate the value and effectiveness of functional and morphological magnetic resonance imaging (MRI), in order to assess the extent of brain injury in a hypoxic-ischaemic piglet model, and further to validate that the ischaemic injury was successfully induced. In this way, we also characterized the Harderian gland. MRI was performed at 1.5 T in anaesthetized piglets (n = 10, 12-36 h of age). Magnetic resonance perfusion and diffusion imaging were performed at different time points, before, during and after the induction of hypoxia-ischaemia. The effects following bilateral clamping of the carotid arteries were also assessed by contrast-enhanced magnetic resonance angiography. Morphological assessment included T1- and T2-weighted imaging, and fat-suppressed T1-weighted imaging before and after contrast medium enhancement. Morphological MRI revealed a prominent, well-defined structure located at the eyeball. Magnetic resonance angiography reconstructed with volume rendering showed this structure to be partially enclosed by large venous sinuses. At dissection, when compared with the magnetic resonance images, the deep gland of the third eyelid, the Harderian gland, corresponded to this structure both in topography and in size. By contrast, the lacrimal gland proper presented as a small, soft and pale structure that was difficult to distinguish from the surrounding connective tissue. At histological examination, the Harderian gland consisted mainly of compact areas of tubuloacinar glands with abundant eosinophilic granules. The present MRI demonstration of the Harderian gland was an accidental finding during an investigation to assess the extent of brain injury in a hypoxic-ischaemic piglet model. The combination of MRI and histology made it possible to detect and describe the Harderian gland in pig. It has generally been studied in rodents and lower vertebrates and is reported to possess various endocrine and exocrine functions.
  Journal of Anatomy 12/2006; 209(5):699-705. · 2.37 Impact Factor
• Article: Morphological and hemodynamic magnetic resonance assessment of early neonatal brain injury in a piglet model.

  Berit H Munkeby, Kristin Lyng, Jahn Frederik Frøen, Eldrid H Winther-Larssen, Jan Henrik Rosland, Hans-Jørgen Smith, Ola Didrik Saugstad, Atle Bjørnerud
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  ABSTRACT: To investigate the utility of functional and morphological magnetic resonance imaging (MRI) to assess the extent of brain injury in a hypoxia-ischemia (HI) piglet model and further to validate that the desired ischemic injury was successfully induced. MRI was performed at 1.5 T in anesthetized piglets (N = 10, age = 12-36 hours). Relative cerebral blood flow (rCBF), time-to-peak (TTP) contrast, and apparent diffusion coefficient (ADC) were estimated at different time points pre-, during, and post-HI. The effect following bilateral clamping of the carotid arteries was assessed by contrast-enhanced MR angiography (MRA) and phase contrast MR angiography (PCA) (N = 4). A linear correlation was observed between relative cerebral perfusion reduction and cerebral ADC during HI (r(2) = 0.85, P < 0.05). There was no correlation between rCBF reduction during 30 minutes of HI and cerebral ADC after 30 or 150 minutes of reperfusion/reoxygenation (RR). The combination of morphological and functional (perfusion and diffusion) MRI enabled consistent assessment of both the presence and absence of complete occlusion as well as the functional significance of the occlusion.
  Journal of Magnetic Resonance Imaging 07/2004; 20(1):8-15. · 2.70 Impact Factor
• Source

  Available from: Erik Fosse

  Article: A novel infraclavicular brachial plexus block: the lateral and sagittal technique, developed by magnetic resonance imaging studies.

  Øivind Klaastad, Hans-Jørgen Smith, Orjan Smedby, Eldrid H Winther-Larssen, Per Brodal, Harald Breivik, Erik T Fosse
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  ABSTRACT: A new infraclavicular brachial plexus block method has the patient supine with an adducted arm. The target is any of the three cords behind the pectoralis minor muscle. The point of needle insertion is the intersection between the clavicle and the coracoid process. The needle is advanced 0 degrees -30 degrees posterior, always strictly in the sagittal plane next to the coracoid process while abutting the antero-inferior edge of the clavicle. We tested the new method using magnetic resonance imaging (MRI) in 20 adult volunteers, without inserting a needle. Combining 2 simulated needle directions by 15 degrees posterior and 0 degrees in the images of the volunteers, at least one cord in 19 of 20 volunteers was contacted. This occurred within a needle depth of 6.5 cm. In the sagittal plane of the method the shortest depth to the pleura among all volunteers was 7.5 cm. The MRI study indicates that the new infraclavicular technique may be efficient in reaching a cord of the brachial plexus, often not demanding more than two needle directions. The risk of pneumothorax should be minimal because the needle is inserted no deeper than 6.5 cm. However, this needs to be confirmed by a clinical study. IMPLICATIONS: A new infraclavicular brachial plexus block method was investigated using magnetic resonance imaging without inserting needles in the volunteers. The study suggests two needle directions for performance of the block and that the risk of lung injury should be minimal. Expectations need to be confirmed by a clinical study.
  Anesthesia & Analgesia 02/2004; 98(1):252-6, table of contents. · 3.29 Impact Factor