Spectral photon-counting CT imaging of colorectal peritoneal metastases: initial experience in rats

Arnaud Thivolet,Philippe Douek,Pierre-Emmanuel Bonnot,Vahan Képénékian,Christophe Blanchet,Loïc Boussel,Salim Si-Mohamed,Pascal Rousset

doi:10.1038/s41598-020-70282-w

Abstract

Computed tomography imaging plays a major role in the preoperative assessment of tumor burden by providing an accurate mapping of the distribution of peritoneal metastases (PM). Spectral Photon Counting Computed Tomography (SPCCT) is an innovative imaging modality that could overcome the current limitations of conventional CT, offering not only better spatial resolution but also better contrast resolution by allowing the discrimination of multiple contrast agents. Based on this capability, we tested the feasibility of SPCCT in the detection of PM at different time of tumor growth in 16 rats inoculated with CC531 cells using dual-contrast injection protocols in two compartments (i.e. intravenous iodine and intraperitoneal gadolinium or the reverse protocol), compared to surgery. For all peritoneal regions and for both protocols, sensitivity was 69%, specificity was 100% and accuracy was 80%, and the correlation with surgical exploration was strong (p = 0.97; p = 0.0001). No significant difference was found in terms of diagnostic performance, quality of peritoneal opacification or diagnostic quality between the 2 injection protocols. We also showed poor vascularization of peritoneal metastases by measuring low concentrations of contrast agent in the largest lesions using SPCCT, which was confirmed by immunohistochemical analyses. In conclusion, SPCCT using dual-contrast agent injection protocols in 2 compartments is a promising imaging modality to assess the extent of PM in a rat model.

Highlights

Peritoneal metastases (PM) are part of the natural history of most abdominal and gynecological malignancies and have long been considered as a terminal disease
Si-Mohamed et al demonstrated that, in peritoneal cavity and abdominal organ imaging of healthy rats, Spectral Photon Counting Computed Tomography (SPCCT) increased the spatial resolution leading to excellent visualization of small peritoneal structures, and the spectral resolution by allowing the differentiation of 2 contrast agents injected in 2 different compartments, i.e. intraperitoneal (IP) and intravenous (IV) injections[33]
We demonstrated the capacity of a prototype SPCCT system to accurately detect peritoneal metastases (PM) in a rat model using dual-contrast agent injection protocols in the peritoneal and vascular compartments at different time of tumor growth

Summary

Introduction

Peritoneal metastases (PM) are part of the natural history of most abdominal and gynecological malignancies and have long been considered as a terminal disease. Si-Mohamed et al demonstrated that, in peritoneal cavity and abdominal organ imaging of healthy rats, SPCCT increased the spatial resolution leading to excellent visualization of small peritoneal structures, and the spectral resolution by allowing the differentiation of 2 contrast agents injected in 2 different compartments, i.e. intraperitoneal (IP) and intravenous (IV) injections[33]. The latter capability offers a specific and quantitative analysis of the contrast agent biodistribution resulting in greater contrast-to-noise ratios of the structures analyzed in comparison to conventional CT images[33]. The purpose of the present study was to assess the capacity of SPCCT to detect PM of colorectal cancer in a rat model using dual-contrast agent injection protocols in 2 compartments (IV and IP)

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