Qualitative and Quantitative Imaging Evaluation of Renal Cell Carcinoma Subtypes with Grating-based X-ray Phase-contrast CT

Margarita Braunagel,Vera Link,Lorenz Birnbacher,Maximilian F Reiser,Mike Notohamiprodjo,Franz Pfeiffer,Julia Herzen,Marian Willner,Manuel Viermetz,Christine Woischke,Katharina Hellbach,Fabio De Marco,Mathias Marschner,Susan Notohamiprodjo,Sigrid Auweter

doi:10.1038/srep45400

Abstract

Current clinical imaging methods face limitations in the detection and correct characterization of different subtypes of renal cell carcinoma (RCC), while these are important for therapy and prognosis. The present study evaluates the potential of grating-based X-ray phase-contrast computed tomography (gbPC-CT) for visualization and characterization of human RCC subtypes. The imaging results for 23 ex vivo formalin-fixed human kidney specimens obtained with phase-contrast CT were compared to the results of the absorption-based CT (gbCT), clinical CT and a 3T MRI and validated using histology. Regions of interest were placed on each specimen for quantitative evaluation. Qualitative and quantitative gbPC-CT imaging could significantly discriminate between normal kidney cortex (54 ± 4 HUp) and clear cell (42 ± 10), papillary (43 ± 6) and chromophobe RCCs (39 ± 7), p < 0.05 respectively. The sensitivity for detection of tumor areas was 100%, 50% and 40% for gbPC-CT, gbCT and clinical CT, respectively. RCC architecture like fibrous strands, pseudocapsules, necrosis or hyalinization was depicted clearly in gbPC-CT and was not equally well visualized in gbCT, clinical CT and MRI. The results show that gbPC-CT enables improved discrimination of normal kidney parenchyma and tumorous tissues as well as different soft-tissue components of RCCs without the use of contrast media.

Highlights

Most renal lesions are incidentally detected in ultrasound or computed tomography (CT) often presenting without clinical symptoms
Previous studies showed an increased soft-tissue contrast, e.g. in breast specimens[13,14,15], atherosclerotic plaques[16,17], liver lesions[18], murine kidneys with and without renal ischemia[19] and other soft-tissue components[20,21]. The purpose of this ex vivo study was to evaluate the potential of grating-based Phase-contrast computed tomography (PC-CT) imaging for the visualization of tumor architecture and for the characterization of different renal cell carcinoma (RCC) subtypes in comparison to attenuation-based CT and magnetic resonance imaging (MRI) and to correlate the results with histopathology as the standard of reference
Qualitative image analysis showed that grating-based PC-CT (gbPC-CT) imaging allowed a reliable differentiation of tumorous tissue of ccRCCs, pRCCs and chromophobe RCC (chrRCC) from normal renal cortex (Figs 2–4)

Summary

Introduction

Most renal lesions are incidentally detected in ultrasound or computed tomography (CT) often presenting without clinical symptoms. Previous studies showed an increased soft-tissue contrast, e.g. in breast specimens[13,14,15], atherosclerotic plaques[16,17], liver lesions[18], murine kidneys with and without renal ischemia[19] and other soft-tissue components[20,21] The purpose of this ex vivo study was to evaluate the potential of grating-based PC-CT (gbPC-CT) imaging for the visualization of tumor architecture and for the characterization of different RCC subtypes in comparison to attenuation-based CT and MRI and to correlate the results with histopathology as the standard of reference

Methods

Results

Conclusion