Evaluation of a preclinical photon-counting CT prototype for pulmonary imaging

Felix K Kopp,Roland Proksa,Philippe Douek,Bernhard Brendel,Alexander A Fingerle,Franz Pfeiffer,Heiner Daerr,Ernst J Rummeny,Andreas P Sauter,Peter B Noël,Daniela Pfeiffer,Salim Si-Mohamed,Sebastian Ehn,Ewald Roessl

doi:10.1038/s41598-018-35888-1

Abstract

The purpose of this study was to investigate a preclinical spectral photon-counting CT (SPCCT) prototype compared to conventional CT for pulmonary imaging. A custom-made lung phantom, including nodules of different sizes and shapes, was scanned with a preclinical SPCCT and a conventional CT in standard and high-resolution (HR-CT) mode. Volume estimation was evaluated by linear regression. Shape similarity was evaluated with the Dice similarity coefficient. Spatial resolution was investigated via MTF for each imaging system. In-vivo rabbit lung images from the SPCCT system were subjectively reviewed. Evaluating the volume estimation, linear regression showed best results for the SPCCT compared to CT and HR-CT with a root mean squared error of 21.3 mm3, 28.5 mm3 and 26.4 mm3 for SPCCT, CT and HR-CT, respectively. The Dice similarity coefficient was superior for SPCCT throughout nodule shapes and all nodule sizes (mean, SPCCT: 0.90; CT: 0.85; HR-CT: 0.85). 10% MTF improved from 10.1 LP/cm for HR-CT to 21.7 LP/cm for SPCCT. Visual investigation of small pulmonary structures was superior for SPCCT in the animal study. In conclusion, the SPCCT prototype has the potential to improve the assessment of lung structures due to higher resolution compared to conventional CT.

Highlights

Over the last decades, high-resolution computed tomography (HR-CT) has demonstrated to be a valuable tool for detection of lung diseases and exploration of the lung[1,2,3,4,5]
We investigate the resolution capabilities of a preclinical spectral photon-counting CT (SPCCT) prototype compared to a conventional CT by evaluating size and shape of lung nodules in a phantom model, measuring the modulation transfer function (MTF) and demonstrating lung structure visualization in an in-vivo acquisition of a rabbit
We investigated high-resolution imaging with a preclinical SPCCT prototype for pulmonary imaging in comparison to a commercially available CT system

Summary

Introduction

High-resolution computed tomography (HR-CT) has demonstrated to be a valuable tool for detection of lung diseases and exploration of the lung[1,2,3,4,5]. While air is carried to the lungs, it passes several structures, including trachea, bronchi, and bronchioles, which have features and structures within – or currently below – the spatial resolution of HR-CT systems When it comes to pathological changes in the lung, HR-CT has a significant role in the diagnostic evaluation and therapy design[6]. Recent developments showed promising results in the areas of abdominal[21,22,23,24,25], cardiovascular[25,26,27,28,29,30], neurological[31,32,33], and nanoparticle imaging[34] In addition to those possibilities, SPCCT will offer an improved spatial resolution due to smaller detector pixel sizes compared to the current clinical standard. We investigate the resolution capabilities of a preclinical SPCCT prototype compared to a conventional CT by evaluating size and shape of lung nodules in a phantom model, measuring the modulation transfer function (MTF) and demonstrating lung structure visualization in an in-vivo acquisition of a rabbit

Objectives

Methods

Results

Conclusion