Mo1637 NOVEL METHOD TO DETERMINE THE DEPTH OF INVASION IN COLORECTAL NEOPLASMS WITH ULTRASOUND ELASTOGRAPHY USING A FORWARD-VIEWING RADIAL-ARRAY ECHOENDOSCOPE

With the increasing use of endoscopy for treating colorectal cancer, accurate diagnosis of the depth of invasion in colorectal neoplasms has become an important clinical issue. Our study aimed to compare the diagnostic ability and clinical efficacy of endoscopic ultrasound elastography (EUS-EG) with those of magnifying chromoendoscopy (MCE) and EUS in diagnosing the depth of invasion in colorectal neoplasms. Patients with superficial colorectal neoplasms evaluated by MCE, EUS, and EUS-EG were enrolled. The primary clinical endpoint was the diagnostic yield differentiating intramucosal and shallow submucosal cancers from deep submucosal and advanced colorectal neoplasms, using the elastic score of colorectal neoplasms (ES-CRN). In addition, validation of ES-CRN was performed using inter- and intra-observer agreement from two expert and two non-expert endoscopists. We examined the diagnostic yield of additional patients prospectively due to these results. Thirty-one patients (33 lesions) with colorectal neoplasms were enrolled. The diagnostic yields (sensitivity, specificity, positive predictive value, negative predictive value and accuracy) of deeply submucosal cancers or advanced colorectal neoplasms, respectively, were as follows: EUS-EG:100%/88.2%/86.7%/100%/93.3%, MCE: 66.7%/94.4%/90.9%/77.3%/81.8% and EUS: 93.3%/77.8%/77.8%/93.3%/84.8%. Interobserver agreement for the ES-CRN was 0.70/0.80 and 0.45/0.40 for the first/second assessment, for the two expert endoscopists and two non-expert endoscopists. Furthermore, we examined additional 33 patients (34 lesions) prospectively. The diagnostic yields of prospective study were as follows, respectively: EUS-EG:83.3%/81.5%/50.0%/95.7%/81.8%, MCE: 75.0%/92.0%/75.0%/92.0%/87.9% and EUS: 85.7%/61.5%/37.5%/94.1%/66.7%. The diagnostic yield was from equal to higher for EUS-EG than for MCE and EUS, with moderate inter and intra-observer agreement, even for non-expert endoscopists. Therefore, EUS-EG may be a useful modality to determine the depth of invasion in colorectal neoplasms.