TY - JOUR
T1 - Impact of Formalin- and Cryofixation on Raman Spectra of Human Tissues and Strategies for Tumor Bank Inclusion
AU - Mirizzi, Giulia
AU - Jelke, Finn
AU - Pilot, Michel
AU - Klein, Karoline
AU - Klamminger, Gilbert Georg
AU - Gérardy, Jean Jacques
AU - Theodoropoulou, Marily
AU - Mombaerts, Laurent
AU - Husch, Andreas
AU - Mittelbronn, Michel
AU - Hertel, Frank
AU - Kleine Borgmann, Felix Bruno
N1 - Funding:
This research was funded by Fondation Cancer, Luxembourg. Furthermore, the project was funded in part by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) Projektnummer: 314061271 – TRR 205 (to MT). M.M. received funding from the Luxembourg National Research Fund (FNR PEARL P16/BM/11192868)
PY - 2024/3/6
Y1 - 2024/3/6
N2 - Reliable training of Raman spectra-based tumor classifiers relies on a substantial sample pool. This study explores the impact of cryofixation (CF) and formalin fixation (FF) on Raman spectra using samples from surgery sites and a tumor bank. A robotic Raman spectrometer scans samples prior to the neuropathological analysis. CF samples showed no significant spectral deviations, appearance, or disappearance of peaks, but an intensity reduction during freezing and subsequent recovery during the thawing process. In contrast, FF induces sustained spectral alterations depending on molecular composition, albeit with good signal-to-noise ratio preservation. These observations are also reflected in the varying dual-class classifier performance, initially trained on native, unfixed samples: The Matthews correlation coefficient is 81.0% for CF and 58.6% for FF meningioma and dura mater. Training on spectral differences between original FF and pure formalin spectra substantially improves FF samples’ classifier performance (74.2%). CF is suitable for training global multiclass classifiers due to its consistent spectrum shape despite intensity reduction. FF introduces changes in peak relationships while preserving the signal-to-noise ratio, making it more suitable for dual-class classification, such as distinguishing between healthy and malignant tissues. Pure formalin spectrum subtraction represents a possible method for mathematical elimination of the FF influence. These findings enable retrospective analysis of processed samples, enhancing pathological work and expanding machine learning techniques.
AB - Reliable training of Raman spectra-based tumor classifiers relies on a substantial sample pool. This study explores the impact of cryofixation (CF) and formalin fixation (FF) on Raman spectra using samples from surgery sites and a tumor bank. A robotic Raman spectrometer scans samples prior to the neuropathological analysis. CF samples showed no significant spectral deviations, appearance, or disappearance of peaks, but an intensity reduction during freezing and subsequent recovery during the thawing process. In contrast, FF induces sustained spectral alterations depending on molecular composition, albeit with good signal-to-noise ratio preservation. These observations are also reflected in the varying dual-class classifier performance, initially trained on native, unfixed samples: The Matthews correlation coefficient is 81.0% for CF and 58.6% for FF meningioma and dura mater. Training on spectral differences between original FF and pure formalin spectra substantially improves FF samples’ classifier performance (74.2%). CF is suitable for training global multiclass classifiers due to its consistent spectrum shape despite intensity reduction. FF introduces changes in peak relationships while preserving the signal-to-noise ratio, making it more suitable for dual-class classification, such as distinguishing between healthy and malignant tissues. Pure formalin spectrum subtraction represents a possible method for mathematical elimination of the FF influence. These findings enable retrospective analysis of processed samples, enhancing pathological work and expanding machine learning techniques.
KW - Raman spectroscopy
KW - machine learning
KW - tumor bank
KW - formalin fixation
KW - cryopreservation
UR - http://www.scopus.com/inward/record.url?scp=85187777194&partnerID=8YFLogxK
UR - https://pubmed.ncbi.nlm.nih.gov/38474679
U2 - 10.3390/molecules29051167
DO - 10.3390/molecules29051167
M3 - Article
C2 - 38474679
SN - 1420-3049
VL - 29
JO - Molecules
JF - Molecules
IS - 5
M1 - 1167
ER -