CT of Kidney Volume in Autosomal Dominant Polycystic Kidney Disease: Accuracy, Reproducibility, and Radiation Dose

Abstract

A utosomal dominant polycystic kidney disease (AD-PKD) is the most common inherited renal disease and is the fourth-leading cause of end-stage renal disease (1-3). ADPKD is progressive in nature, but the rate of progression is variable (4); in light of this variability, a readily available tool to determine individualized rate of progression is valuable in ADPKD management (5). Increases in renal cyst number and size leading to observable enlargement of the kidneys (4) precedes renal dysfunction in ADPKD, often by many years to decades (4). Therefore, quantifying renal enlargement emerged as a robust marker of progression in ADPKD (6,7). This concept was extended to imaging-based classifications (6) used to individualize prognosis and make treatment decisions (8-10). It is now recommended that all patients with ADPKD have an assessment of renal size as part of their initial evaluation (8,10,11). Whereas various methods of renal size assessment have been reported (6,7,12), total kidney volume (TKV) has emerged as the most accurate assessment method and is most strongly associated with clinical outcomes (5). MRIderived TKV is accurate and reproducible but the reference standard method of manual planimetry is time consuming (11,13,14), which limits translation into clinical practice. Alternative methods have been developed that estimate TKV on the basis of a more rapidly obtained series of measurements, although familiarity with these methods is limited in many clinical settings (6,14-16). In addition, image acquisition can be a challenge for clinicians who practice in settings where MRI access is limited (17). CT is known to help provide accurate TKV assessment (6,18), but there are concerns regarding radiation exposure; however, this has not been re-evaluated in the context of modern dosereducing imaging techniques (19).

Identification of osteopontin as a urinary biomarker for autosomal dominant polycystic kidney disease progression

“…Although gene variants can be detected by direct sequencing of the PKD1 and PKD2 genes, distinguishing between gene polymorphisms and pathogenic missense mutations in the absence of family history is difficult [6][7][8][9]. Therefore, in addition to direct sequencing of the PKD1 and PKD2 genes, radiologic analysis of renal cysts is performed for the diagnosis of ADPKD [10][11][12]. Kidney cysts begin in childhood, but the size and number of cysts must be sufficient to be detected in radiographic images.…”

Radiographic Imaging in Autosomal Dominant Polycystic Kidney Disease: A Claims Analysis

“…Further, total kidney volume is a more accurate measure of renal impairment than eGFR, which can capture disease impairment too late when used as the sole prognostic tool. 24 …”

Accuracy, Reproducibility and User Experience With Standardized Instructions for Measurement of Total Kidney Volume in Autosomal Dominant Polycystic Kidney Disease

“…The images used for this study were obtained from our previous study examining the performance of varying image acquisition and TKV measurement protocols. 21 From this collection of scans, a sample of 3 CT scans were chosen by the study team as scans with different volumes and representative of what would be encountered in clinical practice; images of these scans are included in Supplement 2. All participating radiologists performed measurements on the same 3 scans, and the choice of 3 scans to interpret was chosen as a number that would not be overly onerous to encourage participation of radiologists in varying clinical settings.…”

“…The reference standard TKV value for these 3 scans was determined by planimetry which was performed manually but assisted by Image J version 1.51d software. 21 The software was courtesy of the UBC and St Paul’s Hospital Centre for Heart Lung Innovation.…”