Differentiation of Metastatic and Non-Metastatic Mesenteric Lymph Nodes by Strain Elastography in Surgical Specimens.

PURPOSE: To investigate if strain elastography could differentiate between metastatic and non-metastatic mesenteric lymph nodes ex-vivo. MATERIALS AND METHODS: 90 mesenteric lymph nodes were examined shortly after resection from 25 patients including 17 patients with colorectal cancer and 8 patients with Crohn's disease. Ultrasound-based strain elastography was performed with a linear probe. Tissue hardness in lymph nodes was assessed using visual scales and measuring the strain ratio. B-mode characteristics were also recorded. Pathological diagnosis with grading of fibrosis served as the reference standard. RESULTS: 20 lymph nodes were metastatic and 70 lymph nodes were non-metastatic. The strain ratios of metastatic and non-metastatic lymph nodes were significantly different (1.83 vs. 1.42, p = 0.021). The VAS scale (0 - 100) for tissue hardness gave higher mean values for metastatic than non-metastatic nodes, but the difference was not significant (65.5 vs. 55.0, p = 0.055). There was no difference between lymph nodes in Crohn's and non-metastatic cancer specimens. The metastatic lymph nodes were significantly more fibrotic than the non-metastatic lymph nodes by the ordinal fibrosis score (0 - 3). In an ROC analysis, quantitative strain imaging was not superior to the measurement of the short-axis diameter of lymph nodes in differentiating metastatic from non-metastatic mesenteric lymph nodes ex-vivo. CONCLUSION: Strain elastography is correlated to fibrosis in lymph nodes and a significant difference was observed on a group level using the strain ratio. Due to measurement overlap, individual mesenteric lymph nodes could not be identified accurately as metastatic or not in this ex-vivo model by strain imaging alone.

Strain Elastography Evaluation of Rectal Tumors: Inter- and Intraobserver Reproducibility.

PURPOSE: Elastography is a promising method for the identification and differentiation of malignant tissue in several organ systems. The primary aim was to evaluate the inter- and intraobserver reproducibility of endorectal strain elastography differentiation of adenomas and adenocarcinomas. The secondary aim was to compare the performance of strain elastography to endorectal ultrasonography (ERUS) examinations. MATERIALS AND METHODS: Consecutive inclusion of 95 ERUS examinations and 110 elastography video loops with ERUS overlay mode. Video loops were randomized and evaluated by eight observers on two separate occasions. Observers were blinded to all clinical information except the circumferential location of the tumor. A continuous visual analog scale (VAS) and a categorical scale (W-score) were used for elastography evaluation. ERUS loops were T-staged according to the TNM classification system. Histopathological evaluation of surgical resection specimen was used as the reference standard. RESULTS: Strain elastography visual evaluation yielded intraobserver variability from 0.86 to 0.97 and interobserver variability of 0.99. VAS strain elastography differentiation of adenomas (pT0) and adenocarcinomas (pT1 - 4) yielded sensitivity, specificity, accuracy, positive and negative predictive values of 0.94, 0.71, 0.89, 0.92 and 0.78, respectively. The corresponding ERUS values were 0.83, 0.64, 0.79, 0.88 and 0.54, respectively. CONCLUSION: Visual evaluation of elastography loops is highly reproducible in an offline setting with blinded observers, and correlates significantly with pT-stages. Strain elastography performs better than ERUS and might consequently improve staging.

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

AIM: Strain 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. METHOD: A 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. RESULTS: Histopathological 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). CONCLUSION: This 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.

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

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.

Endorectal elastography in the evaluation of rectal tumours.

AIM: Real-time elastography visualizes tissue compliance using an ultrasound platform. Elastography has been used, particularly in the breast, to characterize indeterminate lesions on B-mode imaging as either benign or malignant. The primary aim of this study was to assess the feasibility of routine endorectal elastography to evaluate rectal neoplasia. The secondary aim was to correlate elastography data with histopathological end-points. METHOD: Sixty-nine patients referred to the outpatient clinic of the Department of Colorectal Surgery at Haukeland University Hospital for the evaluation of rectal tumours were included in this prospective cohort study. All patients underwent digital rectal examination, rigid rectoscopy with biopsy, endorectal ultrasonography and endorectal elastography. In each case a strain ratio was calculated, comparing the tumour tissue with adjacent reference tissue that appeared normal on ultrasound scanning. RESULTS: Histopathologically there were 23 adenomas and 45 adenocarcinomas. One patient died before surgical treatment. Adequate elastography images were obtained in 66/69 (96%) patients. Optimal discrimination of malignant and benign lesions was obtained using a strain ratio cut-off value of 1.25 (sensitivity, 0.93; specificity, 0.96; and accuracy, 0.94). CONCLUSION: Endorectal elastography can be performed as an integral part of the clinical evaluation of rectal tumours and has good patient compliance. The method is a promising modality for the discrimination between adenocarcinoma and adenoma of the rectum.