Non-invasive 23Na MRI Identifies Functionally Distinct Cyst Phenotypes in Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by cysts originating from different nephron segments. Researchers developed a non-invasive 23Na MRI method at 7 Tesla that classifies cysts based on their sodium concentration. Two distinct cyst types were identified: high-sodium cysts similar to blood serum and low-sodium cysts. High-sodium cysts originate from proximal tubules, while low-sodium cysts originate from distal tubules and collecting ducts. The V2R receptor, which is the target of tolvaptan therapy, is found exclusively in low-sodium cysts. Analysis of 2,299 cysts in 20 ADPKD patients showed that high-sodium cysts were 1.8-fold more frequent. Patients exhibited significant variability in cyst composition, with low-sodium cysts comprising 4.6% to 83.9% of all cysts. This heterogeneity may influence disease progression and therapeutic response.