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. 2017 Aug 14;4(1):e000151.
doi: 10.1136/bmjgast-2017-000151. eCollection 2017.

Diagnostic accuracy of high-resolution MRI as a method to predict potentially safe endoscopic and surgical planes in patients with early rectal cancer

Svetlana Balyasnikova  1   2   3 , James Read  1   2   4 , Andrew Wotherspoon  1 , S Rasheed  1 , Paris Tekkis  1   2 , Diana Tait  1 , David Cunningham  1 , G Brown  1   2
Affiliations

Diagnostic accuracy of high-resolution MRI as a method to predict potentially safe endoscopic and surgical planes in patients with early rectal cancer

Svetlana Balyasnikova et al. BMJ Open Gastroenterol. .

Abstract

Introduction: Early rectal cancer (ERC) assessment should include prediction of the potential excision plane to safely remove lesions with clear deep margins and feasibility of organ preservation.

Method: MRI accuracy for differentiating ≤T1sm2 (partially preserved submucosa) or ≤T2 (partially preserved muscularis) versus >T2 tumours was compared with the gold standard of pT stage T1sm1/2 versus ≤pT2 versus >pT2. N stage was also compared. The MRI protocol employed a standard surface phased array coil with a high resolution (0.6×0.6×3 mm resolution). The staging data were analysed from a prospectively recorded database of all ERC (≤mrT3b) treated by primary surgery.

Results: Of 65 <mrT3b tumours, 45 were ≤pT2 and 14 were ≤pT1sm2. MRI accuracy for ≤T1sm2 was 89% (95% CI 63% to 87%), positive predictive value (PPV) 77% and negative predictive value (NPV) 92%, and for ≤T2 89% (95% CI 79% to 95%), PPV 93% and NPV 81%. Interobserver agreement between two experienced radiologists was >0.7 suggesting good agreement. 44 out of 65 patients underwent radical surgery and 22 out of 44 were ≤mrT2. MRI accuracy to predict lymph node status was 84% (95% CI 70% to 92%), PPV 71% and NPV 90%. Among the 21 out of 65 (32%) patients undergoing local excision or TEM, 20 out of 21 were staged as MR≤T2 and confirmed as such by pathology. On follow-up, none had relapse. If the decision had been made to offer local excision on MRI TN staging rather than clinical assessment, a significant increase in organ preservation surgery from 32% to 60% would have been observed (difference 23%, 95% CI 9% to 35%).

Conclusions: MRI is a useful tool for multidisciplinary teams (MDTs) wishing to optimise treatment options for ERC; these study findings will be validated in a prospective multicentre trial.

Keywords: ABDOMINAL MRI; COLORECTAL CANCER; ENDOSCOPIC POLYPECTOMY; STAGING.

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Conflict of interest statement

Competing interests: None declared.

Figures

Figure 1
Figure 1
(A) Submucosa has a hyperintense signal on MRI (red arrow) which should be considered partially or fully preserved if at least 1 mm visible on high-resolution T2-WI. Findings confirmed on histopathology (B). (C) If no hyperintense signal present between the tumour invasion portion and muscularis propria, full invasion of the submucosal layer should be considered. Findings confirmed on histopathology (D).
Figure 2
Figure 2
Flow chart demonstrating potential treatment algorithms based on MRI-defined endoscopic and surgical planes. Blue colour indicates scenario 1 and pink colour indicates scenario 2.
Figure 3
Figure 3
Diagram reporting flow of participants though the study (according to STARD recommendations).
See this image and copyright information in PMC

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