Perfusion CT in colorectal cancer: comparison of perfusion parameters with tumor grade and microvessel density

Abstract

Objective: The purpose of this study was to prospectively compare pre-operative computed tomography (CT) perfusion parameters with tumor grade from colorectal adenocarcinoma (CRC) and to correlate pre-operative CT perfusion parameters with microvessel density (MVD) to evaluate angiogenesis in CRC.

Materials and methods: Pre-operative perfusion CTs were performed with a 64-channel multidetector row CT in 27 patients (17 women and 10 men; age range 32-82 years) who were diagnosed with CRC involving the sigmoid and rectum between August 2006 and November 2007. All patients underwent surgery without pre-operative chemotherapy or radiation therapy. Dynamic perfusion CTs were performed for 65 seconds after intravenous injection of contrast medium (100 mL, 300 mg of iodine per mL, 5 mL/sec). Before surgery, blood flow (BF), blood volume, mean transit time (MTT), and permeability-surface area product were measured in the tumor. After surgery, one gastrointestinal pathologist evaluated tumor grade and performed immunohistochemical staining using CD 34 to determine MVD in each tumor. The Kruskal-Wallis test was used to compare CT perfusion parameters with tumor grade, and Pearson's correlation analysis was used to correlate CT perfusion parameters with MVD.

Results: In 27 patients with CRC, tumor grading was as follows: well differentiated (n = 8); moderately differentiated (n = 15); and poorly differentiated (n = 4). BF was higher in moderately differentiated CRC than well differentiated and poorly differentiated CRCs (p = 0.14). MTT was shorter in moderately differentiated than well differentiated and poorly differentiated CRCs (p = 0.039). The MVD was greater in poorly differentiated than well differentiated and moderately differentiated CRCs (p = 0.034). There was no significant correlation between other perfusion parameters and tumor grade. There was no significant correlation between CT perfusion parameters and MVD.

Conclusion: BF and MTT measurement by perfusion CT is effective in predicting moderately differentiated CRCs. However, perfusion CT is limited in distinguishing well differentiated and poorly differentiated CRCs. Pre-operative perfusion CT does not reflect the MVD of CRCs.

Keywords: Angiogenesis; CT; Colon cancer; Perfusion.

Fig. 1

Perfusion CT of rectal cancer in 68 year-old woman. A. Contrast-enhanced CT image shows tumor region of interests within enhancing rectal cancer (arrows) and arterial input (arrowhead) in left iliac artery. B-E. Corresponding functional color maps of rectal tumor (arrow) and iliac artery (arrowhead) for each perfusion parameter [(B) blood flow, (C) blood volume, (D) mean transit time, and (E) permeability surface-area product] are displayed according to color scale.

Fig. 2

Increased CD34 immunostaining in moderately differentiated colorectal adenocarcinomas was observed. Microvessels were defined as single brown-staining endothelial cells with lumen (arrow) and small clusters of brown-staining endothelial cells without lumen (arrowhead) (CD34 immunostaining at × 200 magnification).

Fig. 3

Relationship between CT perfusion parameters (A-D) and microvessel densities (E) of well differentiated, moderately differentiated, and poorly differentiated colorectal adenocarcinoma (CRC). There were significant differences in blood flow (A), mean transit time (C), and microvessel densities (E) between well differentiated, moderately differentiated, and poorly differentiated CRC (p < 0.05).

Fig. 4

Correlation plots of microvessel density (MVD) and CT vascular parameters. (A) blood flow, (B) blood volume, (C) mean transit time, and (D) permeability surface-area product. No perfusion parameters correlated significantly with MVD.