Combined endorectal ultrasonography and strain elastography for the staging of early rectal cancer

Abstract

Aim Strain elastography is a novel approach to rectal tumour evaluation. The primary aim of this study was to correlate elastography to pT stages of rectal tumours and to assess the ability of the method to differentiate rectal adenomas (pT0) from early rectal cancer (pT1-2). Secondary aims were to compare elastography with endorectal ultrasonography (ERUS) and to propose a combined strain elastography and ERUS staging algorithm.Method In all, 120 consecutive patients with a suspected rectal tumour were examined in this staging study. Patients receiving surgery without neoadjuvant radiotherapy were included (n = 59). All patients were examined with ERUS and elastography. Treatment decisions were made by multidisciplinary team (MDT) assessment, without considering the strain elastography examination.Results Histopathology identified 21 adenomas, 13 pT1, 9 pT2, 15 pT3 and one pT4. Mean elastography strain ratios were predictive of T stage (P = 0.01). Differentiation of adenomas from early rectal cancer (pT1-2) had sensitivity, specificity and accuracy of 0.82, 0.86 and 0.84 for elastography and 0.82, 0.62 and 0.72 for ERUS. A combined staging algorithm was developed to identify tumours eligible for local resection. Based on MDT evaluation 32% of tumours later identified as pT0 or pT1 were treated with total mesorectal excision, even though a local excision might have sufficed. Combined ERUS and elastography evaluation would have significantly reduced this number to 9% (P = 0.008).Conclusion Elastography may improve the staging of adenomas and early rectal cancer compared with ERUS alone. Combined ERUS and elastography assessment is likely to further improve the selection of patients for local resection.Keywords Rectal cancer, early-stage rectal neoplasms, elastography, strain ratio, endorectal ultrasound What does this paper add to the literature? This paper is to our knowledge the first to demonstrate the ability of endorectal elastography to improve staging of pT0, pT1 and pT2 rectal tumours, proposing a combined ERUS and elastography approach to early rectal cancer staging.

Elastography and diffusion-weighted MRI in patients with rectal cancer

“…Descriptive statistics were used. Data were analysed with the Number Cruncher Statistical Systems (NCSS 8 Statistical Software, Kaysville, UT, 2012).…”

“…This is a semi-quantification of the tumour hardness using relative strain ratios; however, it seems that elastography using strain imaging may improve the staging of adenomas and early rectal cancer compared with ERUS alone. 8 The advent of acoustic radiation force impulse (ARFI) imaging has enabled objective measurement of tumour elasticity. ARFI uses a short pulse ,1 ms, producing shear waves in the target tissue.…”

Strain Ratio as a Quantification Tool in Strain Imaging

“…Also, in the characterization of thyroid nodules as malignant or benign, SR was reported to have sensitivity of 85-89% with specificity of 80-82% in two meta-analyses [10,11]. In trans-rectal applications in prostate and rectal tumors, SR has been used to improve B-mode identification of malignant tumors with adequate accuracy (ROC-AUC > 90%) [12,13]. The aim of this study was to retrospectively compare variability in strain-based elastography quantified by SR, recorded in three different applications using Real-Time Elastography in homogeneous tissue-mimicking media, in resected tissue from bowel lesions, and during the endoscopic ultrasound (EUS) of focal pancreatic lesions.…”

“…Also, in the characterization of thyroid nodules as malignant or benign, SR was reported to have sensitivity of 85-89% with specificity of 80-82% in two meta-analyses [10,11]. In trans-rectal applications in prostate and rectal tumors, SR has been used to improve B-mode identification of malignant tumors with adequate accuracy (ROC-AUC > 90%) [12,13].…”

Strain Ratio as a Quantification Tool in Strain Imaging<strong> </strong>

“…The SR data in this study were recorded on the Hitachi (Hitachi Medical Corporation, Tokyo, Japan) Extended Combined Autocorrelation Method (ECAM) also known as Real-Time Elastography (RTE) operated on Hitachi HV-900 and Ascendus platforms (version: V16-04 STEP 2). US data were acquired using external linear probes (L54, [9][10][11][12][13]. The phantom used was a standard model made of Zerdine ® (US pat no.…”