The Role of 3-D Endorectal Ultrasound in Rectal Cancer: Our Experience

Abstract

In the last 20 years, endorectal ultrasound (ERUS) has been one of the main diagnostic methods for locoregional staging of rectal cancer. ERUS is accurate modality for evaluating local invasion of rectal carcinoma into the rectal wall layers (T category). Adding the three-dimensional modality (3-D) increases the capabilities of this diagnostic tool in rectal cancer patients. We review the literature and report our experience in preoperative 3-D ERUS in rectal cancer staging. In the group of 71 patients, the staging of preoperative 3-D endorectal ultrasonography was compared with the postoperative morphologic examination. Three-dimensional ERUS preoperative staging was confirmed with morphologic evaluation in 66 out of 71 cases (92.9%). The detection sensitivities of rectal cancer with 3-D ERUS were as follows: T1, 92.8%; T2, 93.1%; T3, 91.6%; and T4, 100.0%; with specificity values of T1, 98.2%; T2, 95.4%; T3, 97.8%; and T4, 98.5%. Three-dimensional ERUS correctly categorized patients with T1, 97.1%; T2, 94.3%; T3, 95.7%; and T4, 98.5%. The percentage of total overstaged cases was 2.75% and that of understaged cases was 6.87%. The metastatic status of the lymph nodes was determined with a sensitivity of 79.1% (19 of 24), specificity of 91.4% (43 of 47), and diagnostic accuracy of 87.3% (62 of 71). In our experience, 3-D ERUS has the potential to become the diagnostic modality of choice for the preoperative staging of rectal cancer.

3D echoendoscopy and miniprobes for rectal cancer staging

“…2) for T1 staging, which is in agreement with previous reports (21,22). With regard to T2 staging, 3D was superior to mp-EUS, which tended to overstage tumors (12,16,17,(22)(23)(24). A very high accuracy for T3 staging was reported for 3D or mp-EUS (12,16,17,(23)(24)(25)(26), whereas mp-EUS had the lowest accuracy in relation to the higher ultrasound frequency for T4 staging, which is in line with current evidence (17,(24)(25)(26)(27).…”

“…These values range between 77 and 93% in previous reports (12,14,16,17). Our findings confirm the high accuracy of 3D-EUS, which is higher than that of conventional EUS.…”

“…However, there is no consensus with regard to this matter (28,29). In fact, this trend to improved accuracy was also observed in other studies (12,17,30,31).…”

“…With regard to T2 staging, 3D was superior to mp-EUS, which tended to overstage tumors (12,16,17,(22)(23)(24). A very high accuracy for T3 staging was reported for 3D or mp-EUS (12,16,17,(23)(24)(25)(26), whereas mp-EUS had the lowest accuracy in relation to the higher ultrasound frequency for T4 staging, which is in line with current evidence (17,(24)(25)(26)(27). The use of 3D for T staging of rectal cancer had the best accuracy with mp and allowed the staging of stenosing tumors, although with some limitations for large masses (e.g., T4 staging).…”

“…It also allows the isolation of structures or lesions of interest and presents them in different perspectives, changing their texture and/or transparency (12)(13)(14)(15). However, the application of 3D-EUS in this setting has rarely been reported (12,14,16,17). Therefore, we aimed to compare RC preoperative staging using C-EUS with 3D-EUS and mp-EUS.…”