Non-contrast low-dose CT can be used for volumetry of ADPKD.

BACKGROUND: Kidney volume provides important information for the diagnosis and prognosis of autosomal dominant polycystic kidney disease (ADPKD), as well as for the evaluation of the effects of drugs such as tolvaptan. Non-contrast computed tomography (CT) is commonly used for volumetry, and this study examined the correspondence and correlation of kidney volume measured by standard-dose or low-dose CT. METHODS: Axial standard-dose and low-dose CT images with 1-mm slices were obtained from 24 ADPKD patients. The kidney was segmented in the Synapse 3D software and the kidney volume was calculated using stereology. The kidney volume was compared between the two sets of images using R2, Bland-Altman plots, coefficient of variation, and intra-class correlation coefficients (ICCs). RESULTS: The mean age of the 24 patients was 48.4 ± 10.9 years, and 45.8% were men (n = 11). The mean total kidney volume on standard-dose CT was 1501 ± 838.2 mL. The R2 of volume between standard-dose and low-dose CT was 0.995. In the Bland-Altman plot, except for one case with a large kidney volume, the two measurements were consistent, and the coefficient of variation and ICC were also good (0.02, 0.998). The CT radiation dose (dose-length product) was 229 ± 68 mGy·cm for standard-dose CT and 50 ± 19 mGy·cm for low-dose CT. A comparable volume was obtained with 20% of the radiation dose of standard-dose CT. CONCLUSIONS: Standard-dose and low-dose CT showed comparable kidney volume in ADPKD. Therefore, low-dose CT can substitute for ADPKD volumetry while minimizing radiation exposure.

Comprehensive analysis of mutations of renal cell carcinoma in an autosomal dominant polycystic kidney disease patient.

Renal cell carcinoma (RCC) is known to be more prevalent in autosomal dominant polycystic kidney disease (ADPKD) patients than in the general population. However, little is known about genetic alterations or changes in signaling pathways in RCC in patients with ADPKD.In the current report, whole-exome and transcriptome sequencing was performed for paired samples of tumor tissue, cyst tissue, and peripheral blood (triple set) from a patient diagnosed with ADPKD and RCC.A 68-year-old man with ADPKD underwent left partial nephrectomy and was diagnosed with RCC. DNA and RNA were extracted from the triple set of the patient. A nonsense mutation in PKD2 (p.Arg742X), which is well known as a pathogenic variant in ADPKD, was identified in the paired triple set. In the tumor sample, a somatic missense mutation of VHL (p.S65L) was found, which is known as a pathogenic mutation in Von Hippel-Lindau syndrome and RCC. Furthermore, loss of chromosome 3p, where VHL is located, was detected. Upregulated VEGFA was found in the analysis of RCC mRNA, which might be caused by the loss of VHL and accelerate angiogenesis in RCC.Proliferation was also expected to be activated by the MAPK signaling pathway, including NRAS and MAPK1 expression.