Assessment of murine brain tissue shrinkage caused by different histological fixatives using magnetic resonance and computed tomography imaging
Hans F. Wehrl1, Ilja Bezrukov1,2, Stefan Wiehr1, Mareike Lehnhoff1, Kerstin Fuchs1, Julia G. Mannheim1, Leticia Quintanilla-Martine3, Ursula Kohlhofer3, Manfred Kneilling1,4, Bernd J. Pichler1 and Alexander W. Sauter1,5
1Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, 2Department of Empirical Inference, Max-Planck-Institute for Intelligent Systems, 3Department of Pathology, Eberhard Karls University Tuebingen, 4Department of Dermatology, Eberhard Karls University Tuebingen and 5Department of Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, Tuebingen, Germany
Offprint requests to: Alexander Sauter, Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Roentgenweg 13, D-72076 Tuebingen, Germany. e-mail: email@example.com
Summary. Especially for neuroscience and the development of new biomarkers, a direct correlation between in vivo imaging and histology is essential. However, this comparison is hampered by deformation and shrinkage of tissue samples caused by fixation, dehydration and paraffin embedding.
We used magnetic resonance (MR) imaging and computed tomography (CT) imaging to analyze the degree of shrinkage on murine brains for various fixatives. After in vivo imaging using 7 T MRI, animals were sacrificed and the brains were dissected and immediately placed in different fixatives, respectively: zinc-based fixative, neutral buffered formalin (NBF), paraformaldehyde (PFA), Bouin-Holland fixative and paraformaldehyde-lysine-periodate (PLP). The degree of shrinkage based on mouse brain volumes, radiodensity in Hounsfield units (HU), as well as non-linear deformations were obtained.
The highest degree of shrinkage was observed for PLP (68.1%, P<0.001), followed by PFA (60.2%, P<0.001) and NBF (58.6%, P<0.001). The zinc-based fixative revealed a low shrinkage with only 33.5% (P<0.001). Compared to NBF, the zinc-based fixative shows a slightly higher degree of deformations, but is still more homogenous than PFA.
Tissue shrinkage can be monitored non-invasively with CT and MR. Zinc-based fixative causes the smallest degree of brain shrinkage and only small deformations and is therefore recommended for in vivo ex vivo comparison studies. Histol Histopathol 30, 601-613 (2015)
Key words: Imaging, Fixation, Paraffin, Shrinkage, Brain