The Diagnostic Performance of MRI for Detection of Extramural Venous Invasion in Colorectal Cancer: A Systematic Review and Meta-Analysis of the Literature

Abstract

OBJECTIVE. The purpose of this article is to perform a systematic review and meta-analysis regarding the diagnostic test accuracy of MRI for detecting extramural venous invasion (EMVI) in patients with colorectal cancer. MATERIALS AND METHODS. PubMed and EMBASE were searched up to November 9, 2018. We included diagnostic accuracy studies that used MRI for EMVI detection in patients with colorectal cancer, using pathologic analysis as the reference standard. The methodologic quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Sensitivity and specificity were pooled and plotted in a hierarchic summary ROC plot. Metaregression analysis using several clinically relevant covariates was performed. RESULTS. Fourteen studies (n = 1751 patients) were included. Study quality was moderate in general. Pooled sensitivity was 0.61 (95% CI, 0.49-0.71), and pooled specificity was 0.87 (95% CI, 0.79-0.92). There was substantial heterogeneity according to the Cochran Q test (p < 0.01) and Higgins I² heterogeneity index (98% and 95% for sensitivity and specificity, respectively). Publication bias was present (p = 0.01). Higher rates of advanced T category, use of high-resolution MRI, and use of antispasmodic drugs were shown to significantly affect heterogeneity (p < 0.01). Location of primary tumor, preoperative treatment status, study design, definition of reference standard, magnetic field strength, and use of functional MRI were not statistically significant (p = 0.17-0.92). CONCLUSION. MRI shows moderate sensitivity and good specificity for the detection of EMVI in colorectal cancer. The use of high-resolution MRI may improve diagnostic performance.

Keywords: MRI; colorectal cancer; extramural venous invasion; meta-analysis; systematic review.

Fig. 1—

Three patients with rectal cancer, two of whom also had MRI-detected extramural venous invasion (EMVI), with corresponding pathologic results. A, 68-year-old man with rectal cancer and MRI EMVI score of 0 (definitely absent) and negative EMVI at histopathologic examination. No definite extramural tumor extension is observed on T2-weighted oblique axial MR image. Normal-caliber perirectal vessels of low signal intensity are shown (arrowheads). B, 61-year-old man with rectal cancer and MRI EMVI score of 2 (indeterminate) with positive EMVI at histopathologic examination. T2-weighted oblique axial MR image shows suspicious extramural tumor stranding (arrow) in vicinity of extramural vessels (arrowheads). However, tumor signal intensity does not extend to these normal-caliber perirectal vessels of low signal intensity. Note there is indeterminate perirectal lymph node (line), which was pathologically confirmed as regional lymph node metastasis. C and D, 44-year-old woman with rectal cancer and MRI EMVI score of 4 (definitely present) with positive EMVI at histopathologic examination. T2-weighted oblique axial MR image (C) shows intermediate tumor signal with serpiginous extension (arrow) along vascular structure (arrowheads). On sagittal MR image (D), irregular tumor signal (arrow) extends cranially from primary rectal cancer along vein of low signal intensity (arrowheads).

Fig. 2—

Flow diagram showing study selection process for meta-analysis.

Fig. 3—

Grouped bar charts of risk of bias (left) and concerns for applicability (right) of 14 included studies using Quality Assessment of Diagnostic Accuracy Studies–2 (QUADAS-2) tool.

Fig. 4—

Coupled forest plots of pooled sensitivity and specificity. Numbers are pooled estimates (dots within squares) with 95% CIs (horizontal lines). Corresponding heterogeneity statistics are provided at bottom right corners. Dashed vertical lines and diamonds indicate overall meta-analytically pooled estimate. Lateral points of diamonds indicate CIs for estimate.

Fig. 5—

Hierarchic summary ROC curve of diagnostic performance of MRI for detection of extramural venous invasion in patients with colorectal cancer.

Fig. 6—

Deeks funnel plot; p = 0.01 suggests that likelihood of publication bias is high. Numbers in circles are study number, in same order as shown in Table I. ESS = effective sample size.