Observational Study
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World J Gastroenterol. Dec 14, 2014; 20(46): 17552-17557
Published online Dec 14, 2014. doi: 10.3748/wjg.v20.i46.17552
Laterally spreading tumors: Limitations of computed tomography colonography
Kazutomo Togashi, Kenichi Utano, Shigeyoshi Kijima, Yosuke Sato, Hisanaga Horie, Keijirou Sunada, Alan T Lefor, Hideharu Sugimoto, Yoshikazu Yasuda
Kazutomo Togashi, Kenichi Utano, Department of Coloproctology, Aizu Medical Center, Fukushima Medical University, Aizuwakmatsu-city, Fukushima 969-3492, Japan
Kazutomo Togashi, Hisanaga Horie, Alan T Lefor, Yoshikazu Yasuda, Department of Surgery, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
Kenichi Utano, Shigeyoshi Kijima, Yosuke Sato, Hideharu Sugimoto, Department of Radiology, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
Keijirou Sunada, Department of Gastroenterology, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
Author contributions: Togashi K and Utano K contributed equally to this work; Kijima K, Sato Y, Horie H and Sunada K performed research; Lefor AT, Sugimoto H and Yasuda Y made a critical revision; Yasuda Y approved the final manuscript.
Correspondence to: Kazutomo Togashi, MD, PhD, Department of Coloproctology, Aizu Medical Center, Fukushima Medical University, 21-2 Maeda, Tanisawa, Kawahigashi, Aizuwakmatsu-city, Fukushima 969-3492, Japan. togashik@fmu.ac.jp
Telephone: +81-24-2752100 Fax: +81-24-2752568
Received: December 10, 2013
Revised: February 10, 2014
Accepted: June 2, 2014
Published online: December 14, 2014
Processing time: 373 Days and 16.7 Hours
Abstract

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.

Keywords: Computed tomography colonography; Laterally spreading tumor; Colon neoplasm; Advanced lesion; Flat adenoma; Detection rate

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.