Endorectal ultrasonography, strain elastography and MRI differentiation of rectal adenomas and adenocarcinomas

Abstract

AimStrain elastography is a method for recording tissue hardness. Strain in different areas may be compared using strain ratio (SR). The aims of this study were to validate a previously proposed SR cut-off value of 1.25 for differentiating adenocarcinomas from adenomas and to compare the performance of endorectal ultrasonography (ERUS), strain elastography and MRI in the same patients.MethodA prospective evaluation of 120 consecutive patients with rectal neoplasia, using a predetermined elastography strain ratio cut-off value, was performed to differentiate adenomas from adenocarcinomas. ERUS and MRI were performed according to standard routine at Haukeland University Hospital, defining T0 as adenomas and T1–T4 as adenocarcinomas. Subsequent histopathology was used as the reference standard.ResultsHistopathological evaluation revealed 21 adenomas and 99 adenocarcinomas. Sensitivity, specificity and accuracy (with 95% CI) were as follows: ERUS: 0.96 (0.90–0.99), 0.62 (0.40–0.80) and 0.90 (0.83–0.94); elastography SR: 0.96 (0.90–0.99), 0.86 (0.66–0.96) and 0.94 (0.88–0.97); and MRI: 0.99 (0.94–1.00), 0.07 (0.00–0.31) and 0.87 (0.80–0.93).ConclusionThis study confirms that the elastography SR assessment accurately differentiates sessile adenomas from adenocarcinomas. SR assessment has a superior ability to differentiate adenomas and adenocarcinomas when compared with ERUS and MRI. MRI examination seems unable to recognize adenomas and should be interpreted with care when early-stage rectal neoplasia is suspected.

Strain Ratio as a Quantification Tool in Strain Imaging

“…After removing the outliers, the evaluation for identification of malignant lesions based on qualitative visual scores and strain histograms outperformed the SR-based evaluation (sensitivity: 0.94, specificity: 0.54, diagnostic odds ratio (OR): 29.42 [17]. However, strain elastography and SR-based assessment of rectal tumors using a dedicated radial rectal probe, which allows induction of strain by rapid water-inflation of a balloon around the US probe, was used to improve patient selection for organ-sparing treatment compared to standard multidisciplinary assessment [18].…”

Endoscopic ultrasound for the characterization and staging of rectal cancer. Current state of the method. Technological advances and perspectives.

“…Color elastography has demonstrated its applicability and usefulness in multiple clinical areas [27], with promising results in TRUS as well. There is hope that the method would help for a better rectal tumor staging and differentiation between adenomas and adenocarcinomas [28]. To identify rectal tumor formations, Waage et al have used the Hitachi equipment with a micro-convex endorectal transducer (5-10 MHz), rigid, with 360-degree US scanning [26].…”

“…At this value, elastography differentiates between benign and malignant lesions much better than preoperative biopsy (Se=93%, Sp=96%, OA=94%; preoperative biopsy: Se=69%, Sp=87%, OA=75%) (fig 4) [26]. Rectal adenoma may be differentiated from adenocarcinoma using color elastography with additional gray scale TRUS value, being superior to MRI (TRUS: Se=96%, Sp=62% and OA=90%; elastography: Se with SR measurement: Se=96%, Sp=86% and OA=94%; MRI: Se=99%, Sp=7% and OA=87%) [28].…”

Characterization and staging of rectal tumors: endoscopic ultrasound versus MRI / CT. Pictorial essay.

“…In terms of cancer staging, elastography, along with TRUS, is useful to distinguish pT0 stage from pT1 stage, with better results than MRI, including pretreatment biopsy. Elastography, additional to TRUS, does not bring additional information regarding T2 and T3 staging, as TRUS is sufficient for final cancer staging [3] (fig 9). To our knowledge, the characterization of pathological lymph nodes did not include their elasticity but, by our experience, these appear more rigid than perirectal fat during elastography (fig 10).…”

“…Among these, endoscopic ultrasound has proven to be the best imaging technique in rectal tumors. A complete endoscopic ultrasound multimodal examination may even surpass biopsy in terms of rectal cancer detection [3,4] Ultrasound techniques 2D and 3D gray scale ultrasound. Endorectal and endovaginal US, in one term endoscopic US, represent the essential test for the local assessment of rectal tu-mors.…”