Karen Masterson

University of Geneva, Genève, Geneva, Switzerland

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Publications (11)18.97 Total impact

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    ABSTRACT: Purpose Head and neck squamous cell carcinoma (HNSCC) may cause a decreased apparent diffusion coefficient (ADC) on diffusion-weighted magnetic resonance imaging (DW MRI) and an increased standardized uptake value (SUV) on fluorodeoxyglucose (FDG) positron emission tomography (PET/CT). We analysed the reproducibility of ADC and SUV measurements in HNSCC and evaluated whether these biomarkers are correlated or independent. Methods This retrospective analysis of DW MRI and FDG PET/CT data series included 34 HNSCC in 33 consecutive patients. Two experienced readers measured tumour ADC and SUV values independently. Statistical comparison and correlation with histopathology was done. Intra- and inter-observer agreement for ADC and SUV measurements was assessed. Results Intraclass correlation coefficient (ICC) analysis showed almost perfect reproducibility (>0.90) for ADCmean, ADCmin, SUVmax and SUVmean values for intra-observer and inter-observer agreement. Mean ADCmean and ADCmin in HNSCC were 1.05 ± 0.34 × 10−3 mm2/s and 0.65 ± 0.29 × 10−3 mm2/s, respectively. Mean SUVmean and mean SUVmax were 7.61 ± 3.87 and 12.8 ± 5.0, respectively. Although statistically not significant, a trend towards higher SUV and lower ADC was observed with increasing tumour dedifferentiation. Pearson’s correlation analysis showed no significant correlation between ADC and SUV measurements (r −0.103, −0.051; p 0.552, 0.777). Conclusion Our data suggest that ADC and SUV values are reproducible and independent biomarkers in HNSCC.
    Full-text · Article · Feb 2013 · European Journal of Nuclear Medicine
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    ABSTRACT: OBJECTIVE: The objective of this article is to review the CT and MR angiography features of vascular injuries to the neck with special emphasis on the key diagnostic features of common and less common entities. CONCLUSION: CT and MR angiography are highly efficient for the diagnosis of most arterial and venous traumatic lesions in the acute setting and when patients develop delayed symptoms. Conventional angiography is recommended only for therapeutic purposes or when the diagnosis remains unclear after performing cross-sectional imaging techniques.
    Full-text · Article · Jun 2011 · American Journal of Roentgenology
  • Andrej Terzic · Minerva Becker · Karen Masterson · Paolo Scolozzi
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    ABSTRACT: Subcutaneous and deep cervical emphysema (SCE) in the head and neck are found in a wide spectrum of conditions. Most of them are seen in patients with midfacial trauma or oropharyngeal infections. Subcutaneous and deep cervical emphysema can also be a symptom of life-threatening mediastinitis and/or necrotizing fasciitis, both of which need immediate surgery. Rarely however does SCE occur in isolation as a consequence of elevated intraoral pressure in combination with or without visible lacerations of the oral mucosa. As a consequence, air penetrates the mucosal tears and results in subcutaneous emphysema even extending down to the mediastinum in severe cases. This article describes a series of five cases of isolated SCE. It discusses the diagnosis, the pathomechanism, the differential diagnosis and the treatment. It underlines the importance of anamnesis and careful physical and laboratory examinations in order to differentiate isolated SCE from more severe conditions such as necrotizing fasciitis or mediastinitis, which necessitate immediate surgery.
    No preview · Article · Apr 2011 · Archives of Oto-Rhino-Laryngology
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    ABSTRACT: This article provides an overview of the imaging findings of diseases affecting the optic nerve with special emphasis on clinical-radiological correlation and on the latest technical developments in MR imaging and CT. The review deals with congenital malformations, tumors, toxic/nutritional and degenerative entities, inflammatory and infectious diseases, compressive neuropathy, vascular conditions and trauma involving the optic nerve from its ocular segment to the chiasm. The implications of imaging findings on patient management and outcome and the importance of performing high-resolution tailored examinations adapted to the clinical situation are discussed.
    Full-text · Article · May 2010 · European journal of radiology
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    F Pazos · K Masterson · C Inan · J Robert · B Walder
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    ABSTRACT: We report the occurrence of a bilateral pneumothoraces after unilateral central venous catheterization of the right subclavian vein in a 70-year-old patient. The patient had no history of pulmonary or pleural disease and no history of cardiothoracic surgery. Two days earlier, she had a median laparotomy under general and epidural anaesthesia. Prior to the procedure, the patient was hemodynamically stable and her transcutaneous oxygen saturation was 97% in room air. We punctured the right pleural space before cannulation of the right subclavian vein. After the procedure, the patient slowly became hemodynamically instable with respiratory distress. A chest radiograph revealed a complete left-side pneumothorax and a mild right-side pneumothorax. The right-side pneumothorax became under tension after left chest tube insertion. The symptoms finally resolved after insertion of a right chest tube. After a diagnostic work-up, we suspect a congenital “Buffalo chests” explaining bilateral pneumothoraces and a secondary tension pneumothorax.
    Full-text · Article · Nov 2009 · Case Reports in Medicine
  • K Masterson · M.I. Vargas · J Delavelle
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    ABSTRACT: To demonstrate the use of perfusion CT in patients presenting with a suspected diagnosis of stroke to avoid the administration of inappropriate thrombolytic therapy in stroke-mimicking conditions such as status epilepticus. We reviewed the imaging studies of four patients presenting with symptoms suggestive of stroke, but finally diagnosed with status epilepticus. Imaging was by a 16-section multidetector CT scanner using a protocol consisting of non-contrast CT, CT angiography and perfusion CT. Color-coded maps allowed calculation of the CBV (cerebral blood volume), CBF (cerebral blood flow) and MTT (mean transit time). In all four cases, perfusion CT revealed increases in CBF and CBV as well as a decreased MTT, consistent with hyperperfusion linked to status epilepticus with focal deficit-in contrast to the hypoperfusion observed in stroke patients. The use of perfusion CT accurately detected hyperperfusion in status epilepticus presenting as stroke. In such cases, perfusion CT imaging avoided the administration of potentially harmful thrombolytic therapy to patients experiencing seizures due to different underlying etiologies.
    No preview · Article · Nov 2008 · Journal of Neuroradiology
  • K. Masterson · M. I. Vargas · J. Delaveile

    No preview · Article · Oct 2008 · Journal de Radiologie
  • K Masterson · L Merlini · K.O. Lövblad

    No preview · Article · Sep 2008 · Journal of Neuroradiology

  • No preview · Article · Feb 2008 · Foot and Ankle Surgery
  • Duy Nguyen · Karen Masterson · Jean-Paul Vallée
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    ABSTRACT: In the field of cardiac MR image segmentation, active contour models, or snakes have been extensively used, owing to their promising results and to the numerous extensions proposed to improve their performance. This paper explores a methodology for evaluating cardiac MR image segmentation algorithms, which assesses the distance between computer-generated and the observer's hand-outlined boundaries. This metric was applied to various external force extensions of the traditional snake, since no systematic comparison has been performed. Cardiac MRI from six patients were analyzed. Imaging was performed on a 1.5 T MR scanner with ECG-gated balanced steady-state free precession (b-SSFP) sequences. Segmentation performances were established for traditional snake, gradient vector flow snake, standard- and guided- pressure force-based snake. The use of a pre-treatment with non-linear anisotropic filtering was also compared to non-filtered images. Agreement between manual and segmentation algorithms was satisfactory for ejection fraction for every segmentation scheme. However end-systolic and end-diastolic volumes were systematically underestimated. The developed regional error metric provided a more rigorous evaluation of the segmentation schemes in comparison to the classical derived parameters based on left ventricle volume estimation, usually used in functional cardiac MR studies. These derived parameters can furthermore mask local segmentation errors.
    No preview · Article · May 2007 · MAGMA Magnetic Resonance Materials in Physics Biology and Medicine
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    ABSTRACT: LEARNING OBJECTIVES Illustrate the use of different CTA techniques for identifying morphological and functional anomalies of cervical and intracranial vessels Educate radiologists about CTA rendering techniques using an interactive multimedia teaching tool Demonstrate the clinical usefulness of 3D CTA imaging and rendering techniques over other imaging modalities ABSTRACT A computed-assisted interactive teaching tour is presented to illustrate the role of CTA in the assessment of acquired and congenital diseases of cervical and cerebral vessels. The different techniques of CTA are demonstrated as well as their limitations. The reconstruction techniques such as MIP, surface and volume rendering, and MPR using adjustable slab thickness are explained and compared with discussion on advantages and disadvantages of these different post-processing techniques. The computer-assisted teaching program allows user to interactively navigate through different image rendering techniques. A review of selected pre- and post-surgical cases include cervical and intracranial arterial (aneurysms, stenosis, arterial plaque morphology, ischemia, occlusion and collateral patterns, dissections, congenital anomalies) and venous (thombosis, malformations) diseases. This interactive teaching tool demonstrates the usefulness of dynamic CTA in well-documented clinical examples
    No preview · Conference Paper · Nov 2005