Abstract
Purpose
This study was performed to determine the apparent diffusion coefficient (ADC) of the normal kidney using diffusion-weighted magnetic resonance imaging (DW-MRI) sequences and to analyse both the changes due to hydration state and results repeatability.
Materials and methods
Ten volunteers underwent DW-MRI imaging of the kidneys with a breath-hold single-shot spin-echo planar imaging (SE-EPI) sequence in the axial and coronal planes with b values of 300, 500, 800 s/mm2, in different states of hydration. Urine osmolarity (OsmU) and sodium excretion (NaU) were measured at the time of each examination. ADC maps were created for all b values, and ADC values were calculated and compared between different states of hydration. In five subjects, the protocol was conducted twice to test data repeatability.
Results
ADC values were lower with higher b values (3.00 vs. 2.47 vs. 1.99×10−3 mm2/s with b values of 300, 500, 800 s/mm2, respectively). ADC values in different hydration states were not statistically different. Measurements were reproducible. OsmU and NaU were statistically different in the different states of hydration (p<0.01).
Conclusions
ADC values significantly decrease with higher b values. Average ADC values in the normal kidney are reproducible. Hydration state does not significantly influence mean ADC values.
Riassunto
Obiettivo
Calcolare con RM pesata in diffusione (RM-DW) i valori del coefficiente di diffusione apparente (ADC) del parenchima renale in volontari sani, valutarne le variazioni in relazione allo stato di idratazione e misurare la ripetibilità delle misure.
Materiali e metodi
È stato condotto studio RM-DW renale con sequenza single-shot Echo planare in breath-hold (SE-EPI) assiale e coronale (valori di b di 300, 500, 800 s/mm2) in 10 volontari sani, in differente stato di idratazione, con controllo di osmolarità urinaria (OsmU) e sodiuria (NaU). Sono state create mappe ADC e valutati i valori di ADC per i differenti valori di b ed in relazione allo stato di idratazione. Al fine di verificare la ripetibilità dei dati in 5 soggetti l’esame è stato ripetuto a distanza di 3 mesi, nelle stesse condizioni.
Risultati
I valori di ADC risultavano 3,00 vs 2,47 vs 1,99×10−3 mm2/s con valori di b rispettivamente di 300, 500, 800 s/mm2. Non si sono osservate differenze significative tra valori di ADC nei diversi stati di idratazione e tra esame basale ed esame ripetuto a distanza di tre mesi. OsmU e NaU erano statisticamente differenti nei diversi stati di idratazione (p<0,01).
Conclusioni
Il valori di ADC misurati sono in accordo con i dati riportati in letteratura e decrescono significativamente al crescere di b. Lo stato di idratazione non influenza significativamente i valori di ADC. Le misurazioni sono ripetibili.
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Damasio, M.B., Tagliafico, A., Capaccio, E. et al. Diffusion-weighted MRI sequences (DW-MRI) of the kidney: normal findings, influence of hydration state and repeatability of results. Radiol med 113, 214–224 (2008). https://doi.org/10.1007/s11547-008-0248-7
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DOI: https://doi.org/10.1007/s11547-008-0248-7