Application Research On Double Contrast-enhanced Endorectal Ultrasonography In Preoperative TN Staging Of Rectal Cancer

Objectives:1. To summarize and analyze the ultrasonographic characteristics of Double contrast-enhanced endorectal ultrasonography (DCEUS) in rectal cancer.2. To evaluate the diagnosis value of DCEUS in the preoperative TN staging of rectal cancer.Methods:Prospective study included 82 patients with rectal cancer who met the inclusion exclusion criteria. Male 51, female 31, ages 24 to 76 years old, average age of (55.18+ 12.31) years. DCEUS and MRI examination were performed in one week before surgery to evaluate the TN staging of tumors. DCEUS examination used HITACHI VISION Preirus ultrasound diagnostic apparatus, end-fire endoprobe EPU-V53W(frequency 7.5MHz), TXP quik-solution gastroenterultrasound developer produced by Huzhou east Asia company, ultrasound contrast agent SonoVue produced by Italy Bracco company. All patients checked by the main senior doctor in blind method. DCEUS contained two steps: rectal perfusion and acoustic contrast.①Rectal perfusion:Cleansing enema was performed advance. Patient kept in left lateral position with knees bent, fully exposed anus. Preliminary understood the location and range of the lesion with digital rectal examination. The gastroenterultrasound developer were injected into the rectum through the disposable anal tube. Inserted the probe to scan the tumor and mark tumor location. Adjusted the gain parameter and focus to clearly display the lesion. In multiple angle and view, the doctor observated the intestinal cavity filling and narrow; measured the range and the thickness of the lesion; recorded the shape,echo,blood flow of lesions,the intestinal wall structure and the relationship between lesions and surrounding organs. For patients with lymph node enlargement, the size, internal echo, boundary and blood flow of lymph were observed and recorded. Images were saved with PACS system. ③ Acoustic contrast:On the basis of rectal perfusion, switched ultrasonic instrument to contrast mode in the optimal display section. Setted mechanical index(MI) 0.07 to 0.09.Bolus injected SonoVue 2.5 to 3.0ml via median elbow vein then flushed pipe with 5.0ml normal saline fleetness immediately. Clock started when injecting SonoVue. Cntinuous dynamic real-time observation the region of interest for 3 minutes. The dynamic image was stored in the ultrasonic instrument after the end of the contrast. Observating by frameplayback, to observe enhancement time, enhancement level, enhancement pattern of tumor tissue and enlarged range of the lesion refer to the normal bowel wall enhancement levels. Analysis of lesion scope,depth of invasion and the surrounding tissues. For patients with lymph node enlargement, acoustic contrast repeated at the best display section of the suspicious metastasis lymph node with an interval of 12min,which the previous injection sonoVue sweeped away. Obtaining valuable information by observe the parenchymal phase, then rapid scanning the surrounding area to see the enlarged lymph nodes. Comprehensive analysis two dimensional image and microcirculation perfusion information to make TN staging by common deliberation of the examiner and another senior doctor.MRI inspection use 1.5T Avanto superconducting magnetic resonance instrument and 8 channel phased array surface body coil, Gd-DTPA injection as contrast agent. Cleansing enema was performed advance. Scan range covered the entire pelvis.All patients underwent routine axial T1WI, sagittal T2WI, coronal T2WI, high-resolution axial T2WI scanning, diffusion weighted imaging (DWI) and enhanced scanning. Two senior radiologists negotiated to decide TN stage by comprehensive analysis of the signal characteristics in different sequences, the strengthen characteristics, the scope, the depth of invasion of the lesion, the enlarged lymph nodes perienteric and other parts of the pelvic cavity.Based on the criteria of histology and pathology, SPSS 17.0 software package was used for evaluating the accuracy and consistency of DCEUS and MRI in the diagnosis of TN staging of rectal cancer by histopathological results. The influence of preoperative adjuvant therapy, tumor location and experience on the diagnostic accuracy of DCEUS were discussed.Results:1. Rectal cancer DCEUS performance contains two parts:rectal perfusion and acoustic contrast. Perfusion imaging reflected the characteristics of the two dimensional image of tumor. Tumors showed low echo uplift, mass or ulcer. Diseased bowel wall thicken, intestinal wall disorder, intestinal lumen stenosis. Color Doppler showed rich blood flow within and surrounding the tumor, the spectrum was of high speed and high resistance. Enlarged lymph nodes showed heterogeneous low echo nodules. CEUS reflects the characteristics of tumor microcirculation. Rectal cancer CEUS performance were divided into 3 types:Type Ⅰ (homogeneous enhancement type), Type Ⅱ (inhomogeneous enhancement type), type Ⅲ(weak enhancement type). Lymph nodes CEUS performance were divided into 4 types:Type Ⅰ(homogeneous strong type), type Ⅱ(inhomogeneous enhancement type), type Ⅲ(edge enhancement type), type IV (low-no enhancement)2. DCEUS and MRI could accurately measure the distance between tumor and anal verge, accurately locate the tumor.3. DCEUS and MRI on T staging accuracy rate were 74.39% and 68.29%, there was no statistically significant difference (P>0.05). DCEUS assessment of T staging was highly consistent with histopathology (Kappa=0.612), MRI was medium consistency (Kappa=0.519)4. The diagnostic accuracy, sensitivity, specificity, positive predictive value and negative predictive value of N staging by DCEUS were respectivel 63.41%,70.91%, 59.26%,78.00% and 50.00%. There was no significant difference between DCEUS and MRI in the accuracy of N staging (P>0.05). DCEUS and MRI evaluation of N staging and pathological staging were poor consistency (the Kappa value were 0.293 and 0.301).5. The diagnostic accuracy of T1～T4 staging in the supplementary treatment group was lower than in the direct operation group, but there was no significant difference between the two groups (P> 0.05)6. The diagnostic accuracy of DCEUS on T staging in the lower, middle and upper rectal cancer was 83.33%,74.29% and 45.45% respectively. T staging accuracy of DCEUS in the upper segment of rectal carcinoma was lower than that in the middle and lower rectal cance (P<0.05). The diagnostic accuracy of DCEUS on N staging in the lower, middle and upper rectal cancer was 66.67%,65.71% and 45.45% respectively. There was no difference in the accuracy of N staging of rectal cancer (P>0.05)7. The diagnostic accuracy of DCEUS on T staging in the prophase, metaphase, anaphase of the study was 52.38%,76.67% and 87.10% respectively. T staging accuracy increased with the experience of ultrasound doctors, the difference was statistically significant (P<0.05). The diagnostic consistency was improved too. The diagnostic accuracy of DCEUS on N staging in the prophase, metaphase, anaphase of the study was 71.43%,60.00% and 61.29% respectively.The accuracy of N staging was not improved with the experience (P>0.05)Conclusions:1.DCEUS can become a reliable diagnosis method and supplementary diagnostic examination of rectal cancer. The value of DCEUS in evaluating tumor location and TN staging were equivalent to the value of MRI. DCEUS has a certain guide for clinical treatment of rectal cancer and the selection of operation mode.2. DCEUS on the T staging in rectal cancer is of high diagnostic value. In particular, the accuracy and consistency of the diagnosis in middle and lower rectal cancer is high. But in terms of N staging accuracy is still to be improved.3. The operator’s experience accumulation can effectively improve the DCEUS’s accuracy of T staging.