Published online Dec 14, 2014. doi: 10.3748/wjg.v20.i46.17552
Revised: February 10, 2014
Accepted: June 2, 2014
Published online: December 14, 2014
Processing time: 373 Days and 16.7 Hours
AIM: To prospectively investigate the detection rate of laterally spreading tumors (LSTs) of the colorectum by computed tomography (CT) colonography (CTC).
METHODS: Patients with LSTs measuring ≥ 20 mm detected during colonoscopy were prospectively enrolled in the study. All patients underwent colonoscopy and subsequent CTC on the same day. CTC was performed using multi-detector CT without contrast in the prone and supine positions. Two radiologists blinded to the existence of LSTs read the virtual endoscopic images as well as 2-D images. LSTs were classified into granular and non-granular types based on colonoscopic appearance.
RESULTS: Forty-seven pathologically proven LSTs were evaluated prospectively. Histology included adenomas in 19, mucosal cancers in 19 and T1 cancers in 9. The mean diameter of the LSTs was 35.1 mm. Twenty-eight (60%) LSTs were correctly identified by CTC, and the configuration was similar to the colonoscopic appearance in most cases. Detection rate for the granular type was significantly higher than that for the non-granular type (71% vs 31%, P = 0.013). Detection rate of adenomas was significantly lower than mucosal cancers (32% vs 79%, P = 0.008) and T1 cancers (32% vs 78%, P = 0.042).
CONCLUSION: The detection rate of LSTs by CTC, particularly the non-granular type was not acceptable. Practitioners should be aware of the relatively low detection rate when using CTC.
Core tip: Laterally spreading tumors (LSTs) are a major target for colon screening. Nevertheless, it is still unknown what percentage of LSTs can be identified with computed tomography (CT) colonography (CTC). It has been reported that CTC may miss flat neoplastic lesions regardless of their size. It is a fascinating clinical question whether non-granular type LSTs, which have a very flat appearance on optical colonoscopy, can be identified with CTC. This study demonstrated that the detection rate of LSTs by CTC, particularly the non-granular type was not acceptable. Practitioners should be aware of the relatively low detection rate when using CTC.