Rheological and Low Field NMR Characterisation of Cystic Fibrosis Patient’s Sputum

• Published in: Chemical and Biochemical Engineering Quarterly 2023-02, Vol.36 (4), p.239-253
• Main Authors: Staltari, G, Biasin, A, Grassi, L, Gerin, F, Maschio, M, Confalonieri, M, Grassi, G, Grassi, M, Abrami, M
• Format: Article
• Language: English
• Subjects: Cultures (Biology); Cystic fibrosis; Diagnosis; low field NMR; Magnetic resonance imaging; mesh size; Methods; rheology; saliva contamination; shear modulus
• ISSN: 0352-9568; 0352-9568; 1846-5153
• DOI: 10.15255/CABEQ.2022.2119

The shear modulus G of the sputum obtained by expectoration from cystic fibrosis patients is fundamental to determine the mesh size of the polymeric network pervading the sputum, a parameter related to lung functionality. The Akaike criterion revealed that in 55.2% of the examined samples, the best approach (among those considered) to determine G relied on the mechanical spectrum fitting by the generalised Maxwell model with relaxation times scaled by a factor 10. Thus, this approach was adopted to evaluate the mesh size distribution combining G knowledge with the determination of the average magnetic relaxation time ([T.sub.2m]) of sputum. As G and [T.sub.2m] determination can be negatively affected by sputum contamination by saliva, whose presence increases [T.sub.2m] and depresses G, we developed a proper "decontamination" procedure to obtain more reliable [T.sub.2m] and G estimations (necessary in 21% of the samples). This procedure allowed to strengthen the [T.sub.2m] correlation with lung functionality evaluated by [FEV.sub.1] (normalised air volume emitted in the first second during a spirometry test). Keywords: rheology, low field NMR, cystic fibrosis, shear modulus, mesh size, saliva contamination