engleski

Developing a non-invasive predictive model for sperm presence in testicular tissue of men with azoospermia

Azoospermia is a condition where there are no spermatozoa in the ejaculate and men who wish to have children undergo testicular sperm extraction (TESE). The success rate of TESE in nonobstructive azoospermia (NOA) is only around 50%. Histological analysis is the only method used for predicting sperm retrieval. The shortcomings are that histology in NOA is heterogeneous and the method is invasive. Magnetic resonance imaging (MRI), on the other hand, can provide whole testis imaging and parameter mapping and is also a non-invasive method. The aim of this study was to assess which parameters obtained with ex-vivo MRI could be useful in predicting testicular histology. 35 samples of testicular tissue were obtained via TESE and all of them underwent 7T MRI, specifically diffusion tensor imaging (DTI), magnetization transfer imaging (MTI) and magnetic resonance spectroscopy (MRS). Images were analysed in ImageJ while the concentrations of metabolites were determined using the QUEST algorithm of the jMRUI software and tetramethylsilane (TMS) as a reference. Samples were then histologically processed, analysed, and divided into groups based on their mean Johnsen score: JS<2, JS≥2, JS≤4, 4<JS<8, and JS≥8. The apparent diffusion coefficient (ADC) was higher in samples with a lower mean Johnsen score which reflects the higher level of water diffusion in tissue with lower cell density. The difference was statistically significant (p<0, 05) between each group. Fractional anisotropy (FA) was significantly lower (p<0, 05) in the group with a mean JS<2 compared to the other samples which could reflect less restricted water diffusion in tissues with the lowest cell density. Magnetisation transfer ratio (MTR) which reflects the density of macromolecules in tissue did not differ significantly between histological groups. Concentrations of myo- Inositol, choline and phosphoethanolamine were significantly different (p<0, 05) between all groups. ADC, FA and concentrations of myo- Inositol, choline and phosphoethanolamine could, thus, be useful in a non- invasive predictive model for sperm presence in testicular tissue and will be used in its further development. Differential concentrations of metabolites could also point to differences in the regulation of spermatogenesis and warrant further research.

Sperm retrieval, Azoospermia, Testis, Magnetic resonance spectroscopy, Magnetic resonance imaging

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