Dual Energy Spectral CT Imaging for Colorectal Cancer Grading: A Preliminary Study
February
Dual Energy Spectral CT Imaging for Colorectal Cancer Grading: A Preliminary Study
Hong-xia Gong 0 1 2
Ke-bei Zhang 0 1 2
Lian-Ming Wu 0 1 2
Brian F. Baigorri 0 1 2
Yan Yin 0 1 2
Xiao- chuan Geng 0 1 2
Jian-Rong Xu 0 1 2
Jiong Zhu 0 1 2
0 Funding: This study was supported by the National Basic Research Program of China (no. 2012CB932600) and Shanghai Leading Academic Discipline Project , no. S30203
1 Editor: Gayle E. Woloschak, Northwestern University Feinberg School of Medicine, UNITED STATES
2 1 Department of Radiology, Renji Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai, 200127, China , 2 Department of Radiology, The University of North Carolina , Chapel Hill, North Carolina, 27516 , United States of America
Objectives
OPEN ACCESS
Competing Interests: The authors have declared
that no competing interests exist.
To assess the diagnostic value of dual energy spectral CT imaging for colorectal cancer grading using the quantitative iodine density measurements in both arterial phase (AP) and venous phase (VP).
Methods
81 colorectal cancer patients were divided into two groups based on their pathological
findings: a low grade group including well (n = 13) and moderately differentiated cancer (n =
24), and a high grade group including poorly differentiated (n = 42) and signet ring cell
cancer (n = 2). Iodine density (ID) in the lesions was derived from the iodine-based material
decomposition (MD) image and normalized to that in the psoas muscle to obtain normalized
iodine density (NID). The difference in ID and NID between AP and VP was calculated.
Results
The ID and NID values of the low grade cancer group were, 14.65±3.38mg/mL and 1.70
±0.33 in AP, and 21.90±3.11mg/mL and 2.05± 0.32 in VP, respectively. The ID and NID
values for the high grade cancer group were 20.63±3.72mg/mL and 2.95±0.72 in AP, and
26.27±3.10mg/mL and 3.51±1.12 in VP, respectively. There was significant difference for
ID and NID between the low grade and high grade cancer groups in both AP and VP (all p<0.001). ROC analysis indicated that NID of 1.92 in AP provided 70.3% sensitivity and 97.7% specificity in differentiating low grade cancer from high grade cancer.
Conclusions
The quantitative measurement of iodine density in AP and VP can provide useful information to differentiate low grade colorectal cancer from high grade colorectal cancer with NID in AP providing the greatest diagnostic value.
Introduction
Colorectal cancer (CRC) has become a very common malignant tumor and one of the leading
causes of cancer-related death in western countries [
1
] and more so in China in recent years.
The 5-year survival rate following surgical intervention is approximately 50% [
2
]. Most studies
have focused on colorectal cancer staging [
3–7
]. However, few studies have evaluated tumor
grading. Tumor grade closely relates to degree of malignancy. A higher tumor grade suggests a
poorer prognosis and reduced tumor cell differentiation. This also implies an easier ability to
metastasize and higher rate of recurrence [
8
]. Adenocarcinoma is the most common type of
colorectal cancer. According to the fourth edition of WHO Classification of Tumors of the
Digestive System [
9
], adenocarcinoma is graded predominantly on the basis of the extent of
glandular appearance, and should be divided into well, moderately and poorly differentiated
types. Another method of classification is to divide the cancer into low-grade (encompassing
well and moderately differentiated adenocarcinomas) and high-grade (including poorly
differentiated adenocarcinomas and undifferentiated carcinomas). Poorly differentiated
adenocarcinomas should show at least some gland formation or mucus production; tubules are typically
irregularly folded and distorted. For this study we employed the latter classification method.
Modern imaging technology allows for detection and noninvasive staging of disease. Large
tumors can be detected by conventional barium enema, while air-contrast radiography
improves the visualization of less advanced lesions. Examinations such as CT, MRI, and
transrectal ultrasonography, allow for the assessment of local tumor invasion and the presence of
locoregional and distant metastases [
10
]. But the tumor grading research through CT imaging
is seldom for lack of quantitative density measurement. Dual energy spectral CT (DEsCT) was
recently introduced as a method of furthering diagnostic capabilities. Different from previous
dual energy approaches, DEsCT employs a single x-ray tube producing dual energy spectra
through rapidly alternating high and low tube voltage [
11, 12
]. Spectral CT produces a material
decomposition (MD) image pair (e.g. water- and iodine-based material decomposition images)
for accurate material density quantification. The aim of this study is to assess the feasibility and
diagnostic value of dual energy spectral CT imaging for colorectal cancer grading using the
quantitative i (...truncated)