gms | German Medical Science

61st Annual Meeting of the German Society of Neurosurgery (DGNC) as part of the Neurowoche 2010
Joint Meeting with the Brazilian Society of Neurosurgery on the 20 September 2010

German Society of Neurosurgery (DGNC)

21 - 25 September 2010, Mannheim

Nanoscaled liposomes increase homogeneity in contrast enhanced ultrasound imaging

Meeting Abstract

  • Andreas Becker - Klinik für Neurochirurgie, Universitätsklinikum Marburg, Deutschland
  • Elena Marxer - Institut für pharmazeutische Technologie und Biopharmazie, Philipps-Universität Marburg, Deutschland
  • Jana Brüßler - Institut für pharmazeutische Technologie und Biopharmazie, Philipps-Universität Marburg, Deutschland
  • Udo Bakowsky - Institut für pharmazeutische Technologie und Biopharmazie, Philipps-Universität Marburg, Deutschland
  • Christopher Nimsky - Klinik für Neurochirurgie, Universitätsklinikum Marburg, Deutschland

Deutsche Gesellschaft für Neurochirurgie. 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010. Mannheim, 21.-25.09.2010. Düsseldorf: German Medical Science GMS Publishing House; 2010. DocV1696

DOI: 10.3205/10dgnc167, URN: urn:nbn:de:0183-10dgnc1674

Published: September 16, 2010

© 2010 Becker et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

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Objective: In neurosurgery ultrasound (US) contrast enhanced imaging is used in brain perfusion measurement or in the diagnosis of vasospasm after subarachnoidal hemorrhage. Texture and homogeneity of contrast enhanced US is a crucial criteria of image quality in brightness mode e.g. in cerebral tumor imaging. The aim of our study was to examine the contrast properties of ideally sized 100 nm liposomes made of dipalmitoylphosphatidylcholine (DPPC), distearoylphosphatidylcholine (DSPC), cholesterol (CHOL) and polyethyleneglycol-40stearate (PEG-40-STEA) compared to the commercial available SonoVue. To obtain texture and homogeneity of US images, the box-counting fractal dimension D_B and lacunarity lambda (l) was used in this study.

Methods: Phased inversion harmonic imaging of a medical US device (Siemens SonoLine Elegra) equipped with a 2.5 MHz phased array transducer was used to measure the second harmonics of the samples in a flow model. Fundamental frequency was 1.4 MHz with a MI of 0.4. US images of 8, 10, 12, 16, 30 and 60 seconds after administration of the liposomes were digitally preprocessed to obtain white spots on a black background that indicates contrast enhancement. A variable (e) was computed as box-size divided by image-size. The number of pixels in each (e)-sized box was counted and (l) for each grid was calculated from the standard deviation and mean. Slopes of (l) were used for statistics. Low slope values indicate homogeneity of digital images, high values of DB indicate minimal alterations in texture.

Results: Lowest slope values were obtained from DPPC/PEG-40-STEA. We found significant lower (l) values compared to SonoVue (p<0.01) for the first 30 seconds of insonation. We found no significant differences in lacunarity within the DPPC/PEG-40-STEA time-series (p=0.95). Highest values of lacunarity were obtained from DPPC/CHOL. For DPPC/PEG-40-STEA we found slightly changes in DB during insonation. Our results could be explained by the modelling of the Rayleigh-Plesset-equation. The resonance frequency of a microbubble is inversely proportional to the bubble radius and proportional to the shell stiffness.

Conclusions: The nanoscaled DPPC/PEG-40-STEA could be a promising contrast agent in US diagnostics e.g. of vascularisation in intracerebral tumors, target drug delivery, and functional US in ischemic diseases like stroke or cerebral vasospasm. Furthermore, D_B and (l) could be a valid and reliable mathematical tool to describe contrast enhanced US imaging.