3D Endosonography Research Articles

Does a learning curve exist in endorectal two-dimensional ultrasound accuracy?

Dear Sir,We read with interest the paper in Techniques in Colo-proctologybyMorrisetal.[1]whereatwo-dimensional(2D)probe was used in rectal cancer staging. We feel it importantto mention the value of three-dimensional (3D) endosonog-raphy, which we now use routinely in our department.Display of volume data in three perpendicular planesfacilitates the interpretation of ultrasound images andenhances the diagnostic information provided by the data.The comparative accuracy for both techniques is similaraccording to the literature. Tumor invasion prediction hasbeen shown to be 84 and 88 % for 2D and 3D endoson-ography, respectively. In the determination of lymph nodeinvolvement, 3D and 2D endoscopic ultrasound (EUS)provide accuracy rates of 79 and 74 %, respectively [2].However, 3D has obvious advantages. With the use of2D EUS, no direct information is available about the lon-gitudinal extent of the tumor and its spatial relationships.Consequently, a series of transverse images must be inte-grated by the observer to produce a mental impression ofthe real anatomy. This means repeated movements of thescan plane over the region of interest, which can be time-consuming, embarrassing, and painful for the patient. With3D EUS, data from a series of closely spaced 2D imagesare combined to create a 3D volume displayed as a cube.The cube does not remain fixed; it can be freely rotated,rendered, tilted, and sliced to allow the operator to infi-nitely vary the different section parameters and visualizethe lesions at different angles in order to get the mostinformation out of the data.The multiview function also allows up to six differentand specialized views at once with real-time reconstruc-tion. This allows the physician to evaluate arbitrary planesnot available with 2D ultrasound, to improve assessment ofcomplex anatomic situations by 3D display, to measureorgan dimensions and volumes, and to standardize theultrasound examination procedures [3].3D scanning may also allow visualization of obstructingtumors by using reconstructed planes in front of thetransducer, possibly improving therapy planning inadvanced rectal cancer by selecting patients who requireneo-adjuvant therapy.Finally, 3D imaging makes EUS less operator dependentas data can easily be stored on a hard disk allowing a real-time reexamination at a later date without loss of infor-mation, such as in discussion of images at cancer multi-disciplinary team meetings.3D ultrasound facilitates the interpretation of the scanimages and improves the diagnostic confidence in approxi-mately 60 % of the examinations [4].

P-0284 Importance of Endorectal Sonography in Rectal Cancer Staging (Poster Presentation)

ABSTRACT Introduction The staging of rectal cancer is a crucial part of the complex therapy of this form of cancer. The purpose of this study was to assess the diagnostic validity of three- dimensional (3D) endoluminal ultrasound at preoperative 3D staging of rectal cancer (uT). Methods The preoperative staging of rectal cancer has been made at our Surgical Department for 20 years. The method of 3D endosonography was introduced in 2000. During the period from 8/2005 to 12/2010, the 3D endorectal sonography was used in 236 examination of rectal tumour. Malignant rectal cancer was diagnosed in 156 patients and that method was indicated in 80 cases for adenomatous or villous rectal polypus. Endosonography shows 5 layers of the rectal wall – three hyperechogenic layers (mucous, submucous, periproctal adipose tissue) and two hypoechogenic layers (muscularis mucosae, muscularis propria). Tumours of uT1 stage show the infiltrated mucous layer and submucosa. Tumours of uT2 stage infiltrate the muscularis propria, uT3 carcinomas infiltrate the whole rectal wall up to the periproctal adipose tissue, and uT4 carcinomas infiltrate the periproctal adipose tissue or adjacent organs. All our patients underwent surgical intervention. Endorectal approach by using an operation rectoscope was applied by patients with uT1 and uT2 stage who had tumour of 3 cm in diameter of G1-2 grading. All surgical samples were examined by one histopathologist. Results The preoperative rectal cancer staging by 3D endorectal sonography correlated with histopathology in 136 patients (87.5%). The up-staging by 3D endorectal sonography was seen in 16 patients (10.3%). The up-staging was assessed in 7 cases of histopathologic pT1 stage evaluated by endorectal sonography as uT2, in 6 patients with histopathologic stage pT2 evaluated as uT3 and in 3 cases of histopathologic pT3 stage evaluated by endorectal sonography as uT4. The down-staging at 3D endorectal sonography was seen in 4 patients (2.3%). It was histopathologic stage pT4 evaluated by endorectal sonography as uT3-T4. Conclusion The data indicate that the preoperative staging of malignant rectal cancer by 3D endorectal sonography results in 100% detection only in the pT1 stage. In pT2 stage the staging accuracy of 3D endorectal sonography was the lowest at 75%, but in stage pT3 it was 85.5% and in pT4 it was 94%. According to our experience, the interpretation of findings obtained by 3D endorectal sonography at limits of T2 – T3 and T3 – T4 is the most difficult. The reason for this is the peripheral reactive fibrous and inflammatory reaction near the tumor tissue often involves the adjacent rectal wall and it echogenecity is the same as the tumor and this results in the overestimation of invasion depth during endorectal sonography of cancer.

Three-dimensional endoluminal ultrasound-guided interstitial brachytherapy in patients with anal cancer

New techniques using image guidance other than computed tomography (CT) and traditional two-dimensional (2D) endosonography might improve interstitial brachytherapy in patients with anal cancer. To investigate a new technique guided by three-dimensional (3D) endosonography used in our institution. Seventeen patients with anal carcinoma were referred to interstitial brachytherapy under 3D endosonographic guidance after external radiotherapy. The procedure was initiated by anal endosonography performed with a 10-MHz rotating endoprobe. Cross-sectional images of the anal sphincters were stored on a 3D system during retraction of the endoprobe through the anal canal. Afterward, any projection could be reconstructed. From this scanning, the optimal positioning of the needles was determined. The needles were inserted through holes in an externally fixated anal template. A repeated endosonography assured that optimal tumor coverage could be obtained by adjusting the number, dwell positions, and/or position of the needles. In all patients, endosonography was able to visualize the extension of the tumors and the position of each needle in 3D. 3D endosonography guidance of interstitial brachytherapy in anal carcinoma seems to optimize the implant procedure and offer better information for dose planning.

A novel procedure to assess anismus using three‐dimensional dynamic anal ultrasonography

This study aimed to determine the value of three-dimensional (3D) dynamic endosonography in the assessment of anismus. Sixty-one women submitted to anorectal manometry were enrolled including 40 healthy women and 21 patients with anismus diagnosed by manometry. Patients were submitted to 3D endosonography. Images were acquired at rest and during straining and analysed in axial and midline longitudinal planes. Sphincter integrity was quantified. The angle between the internal edge of the puborectalis with a vertical line according to the anal canal axis was calculated at rest and during straining. The angle increased in 39 of the 40 normal individuals and decreased in all patients with anismus during straining compared with the angle at rest (88.36 degrees ) and straining (98.65 degrees ) in normal individuals. In the anismus group, the angle decreased at rest (90.91 degrees ) and straining (84.89 degrees ). The difference between angle sizes in normal and anismus patients during straining was statistically significant (P < 0.5). Three-dimensional endosonography is a useful method to assess patients with anismus confirming the anorectal manometric results.

Detection Rate of Periintestinal Lymph Nodes

Compared to standard two-dimensional (2D) endosonography, three-dimensional (3D) endosonography has been presented as a possible improvement regarding imaging of the gastrointestinal (G-I) tract and detection of metastatic lymph nodes. The aim of this study was to evaluate the efficacy of detecting periintestinal lymph nodes in surgical specimens using 3D endosonography. Surgical specimens from 31 patients with malignant G-I tumours were investigated by 3-D endosonography and histology with focus on the presence of periintestinal lymph nodes and presence of metastasis. The specimens were scanned submerged into water. Position and size of the lymph nodes were mapped on a photo of the specimen both by the pathologist and the examiners. Three-dimensional endosonography detected 48 out of 60 malignant lymph nodes (80.0 %), and 110 out of 219 benign lymph nodes (50.2 %). The positive predictive value for an endosonographic finding interpreted as a lymph node was 0.97. The detection rates for periintestinal lymph nodes were relatively high and seemed superior to the one usually assigned to 2D endosonography. Although distinguishing between metastatic and non-metastatic lymph nodes remains a problem, all patients with histologically confirmed metastasis to lymph nodes were detected by 3D endosonography, and the technique thus seems suitable for grouping of patients prior to surgery.

Three‐dimensional reconstruction of endosonographic images of gastric lesions: Preliminary experience

This study was conducted to assess the ability of the endoluminal sonographic probes to image upper gastrointestinal lesions detected with conventional endoscopy and to reconstruct 3-dimensional (3D) images. Sonographic images were obtained from 25 gastrointestinal lesions in 22 patients using a sonographic miniprobe manually drawn at a set speed across lesions detected during conventional endoscopy. 3D images were then reconstructed using an in-house software program. In 16 lesions (64%), the 3D sectional images were evaluated as good, and all 25 lesions (100%) could be visualized both transversely and longitudinally. In 12 lesions (48%), the 3D display of the endosonographic surface image corresponded to the endoscopic appearance. In all 11 cases of gastric cancer, the depth of tumor invasion measured using the 3D image was consistent with the histologic diagnosis (100% accuracy). When videotaped sonographic images were stored on a hard disk, it took an average of 3.5 minutes to obtain and display 3D images of the targeted area. 3D sonographic reconstructions of digestive lesions were useful in diagnosis, and we believe that further improvements should enhance the clinical usefulness of 3D endosonography.

3D endosonography to clarify distal ureteral processes

Evaluation of 3D endoluminal sonography as a diagnostic modality in lower ureteral pathologies. Between December 93 and December 97, 36 consecutive patients with negative findings on IVP and still suspected ureteral obstruction were referred for transrectal or transvaginal endosonography. Patients mean age was 63 years and all of them presented clinically obvious symptoms such as colic pain and miction disturbances. In 31 of 36 patients (86%) 3D endosonography was diagnostic although previous IVP was negative. Reasons for ureteral obstructions were ureteral calculi in 23, urological tumours in 5 and rectal carcinoma in two cases. In one patients a gynecological tumour caused the symptomatology. In the remaining 5 patients CT/MRT or invasive retrograde ureterography/ureteroscopy had to be performed for the final diagnosis. The use of 3D endosonography shows encouraging results in the diagnosis of distal ureteral pathologies. In case of negative findings on IVP it should therefore precede invasive diagnostic modalities or cost intensive imaging techniques.

Evaluation and biopsy of recurrent rectal cancer using three-dimensional endosonography.

The value of endorectal ultrasonography for postoperative follow-up of rectal cancer is limited by the inability to distinguish recurrent malignancy from benign lesions, e.g., fibrotic tissue. This study was conducted to investigate the role of three-dimensional (3D) endosonography for evaluation and biopsy of recurrent rectal cancer. Endorectal ultrasonography was performed in routine follow-up program after resection of rectal cancer. 3D volume scans were recorded using a bifocal multiplane 3D transducer (7.5/10 MHz) with a 100 degrees longitudinal and a 360 degrees transversal scan angle. For transrectal ultrasound-guided biopsy of pararectal lesions, a specially designed targeting device was attached to the endoprobe. Overall pararectal lesions were detected in 28 of 163 patients (17 percent) who were undergoing endorectal ultrasonography for follow-up after resection of rectal cancer. 3D image analysis facilitated assessment of suspicious pararectal lesions by contemporary display of three perpendicular scan planes or volume reconstructions of the scanned area. Ultrasound-guided biopsy was performed in all 28 patients with pararectal lesions identified by endorectal ultrasonography. Biopsy revealed recurrent disease or lymph node metastases in seven and two patients, respectively. Benign lesions explained the endosonographic findings in 17 patients. All patients with benign histology still have no evidence of recurrent disease after a median follow-up of seven months. Nonrepresentative material was obtained in only 2 of 28 patients (accuracy, 93 percent). Histology changed the endosonographic diagnosis in 28 percent of cases. 3D endosonography with ultrasound-guided biopsy improves the diagnosis of extramural recurrence after curative resection of rectal cancer. 3D image display allows precise control of the position of the biopsy needle within the target.