Stability and sensitivity of water T

Autor: Christopher D J, Sinclair, Jasper M, Morrow, Robert L, Janiczek, Matthew R B, Evans, Elham, Rawah, Sachit, Shah, Michael G, Hanna, Mary M, Reilly, Tarek A, Yousry, John S, Thornton
Rok vydání: 2016
Předmět:
Zdroj: Nmr in Biomedicine
ISSN: 1099-1492
Popis: Quantifying muscle water T 2 (T 2‐water) independently of intramuscular fat content is essential in establishing T 2‐water as an outcome measure for imminent new therapy trials in neuromuscular diseases. IDEAL‐CPMG combines chemical shift fat–water separation with T 2 relaxometry to obtain such a measure. Here we evaluate the reproducibility and B 1 sensitivity of IDEAL‐CPMG T 2‐water and fat fraction (f.f.) values in healthy subjects, and demonstrate the potential of the method to quantify T 2‐water variation in diseased muscle displaying varying degrees of fatty infiltration. The calf muscles of 11 healthy individuals (40.5 ± 10.2 years) were scanned twice at 3 T with an inter‐scan interval of 4 weeks using IDEAL‐CPMG, and 12 patients with hypokalemic periodic paralysis (HypoPP) (42.3 ± 11.5 years) were also imaged. An exponential was fitted to the signal decay of the separated water and fat components to determine T 2‐water and the fat signal amplitude muscle regions manually segmented. Overall mean calf‐level muscle T 2‐water in healthy subjects was 31.2 ± 2.0 ms, without significant inter‐muscle differences (p = 0.37). Inter‐subject and inter‐scan coefficients of variation were 5.7% and 3.2% respectively for T 2‐water and 41.1% and 15.4% for f.f. Bland–Altman mean bias and ±95% coefficients of repeatability were for T 2‐water (0.15, −2.65, 2.95) ms and f.f. (−0.02, −1.99, 2.03)%. There was no relationship between T 2‐water (ρ = 0.16, p = 0.07) or f.f. (ρ = 0.03, p = 0.7761) and B 1 error or any correlation between T 2‐water and f.f. in the healthy subjects (ρ = 0.07, p = 0.40). In HypoPP there was a measurable relationship between T 2‐water and f.f. (ρ = 0.59, p
Databáze: OpenAIRE
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