| Objective:To explore rectal cancer reasonable MRI scan technology, summarizes its in MRI and DCE-MRI the imaging findings, and assess the value of DCE-MRI in the preoperative staging of rectal cancer.Materials and Methods:1. Normal volunteers:30 health volunteers' the pelvic scan were imaged with routine MRI examination, each gender have 15 people. The average age of male people is 29.4, the femal people is 24. All of the volunteers were without operation of colon and rectum history. All the volunteer were admitted to have the MRI scan.2. Anatomical specimens:Seven speciments of cadaver pelvic,4 males and 3 females.1 received the routin examination.3. Case group:49 patients of rectal carcinoma were preoperatively assessed by routin MRI, high resolution and DCE-MRI with a phased array coil. The male 28 patients,female 21 patients, median age 67. Inclusion criteria:Never accept radiotherapy or and chemotherapy and have complete MRI material, and surgery healers. Exclusion criteria:acceptance the pelvic radiotherapy or and chemotherapy.4. MR scan was performed on GE 1.5 T signa scanner with phased array coil. Scan range from the sigmoid colon and rectal border area (L5-S1) to the anus.Compare the distance which measurement methods between in sagittal MRI and postoperative measurement MRI inferior margin from anus distance, using matching t test, P<0.05 for difference have statistically significant; On the normal bowel wall and rectal lesions to the signal intensity (SImax), peaked time (Tpeak), within the first 1 min injection of contrast the biggest signal strength (Sl1min), early increase rate (SIR) data, using matching t test, P<0.05 for difference have statistical significance. Results:1.①Rectum wall By the rectal wall anatomy biopsy showed mucosal layer, muscularis mucosa, submucosa, muscularis propria.And serosal layer (or coating) composition. The T2WI MRI of the rectum is divided into only two-story structure, the center side of the circle of high signal ring, that is, mucosa and submucosa, and peripheral side of the low signal ring, that is, the muscularis propria and the coating layer. MRI can only distinguish the mucosa and submucosa and muscularis propria and the coating layer, can not distinguish between mucosa and submucosa; muscularis propria and the coating layer. In addition, the outer edge of the rectal wall on T2WI often see incomplete linear low signal intensity, often located in the side wall, and the direction of the relevant code, but not the capsule due to chemical shift artifact.②Mesorectum In the biopsy and autopsy, the mesorectum is located around the rectum, behind the thick, on both sides of the second, mainly to adipose tissue, generally cylindrical shape similar to, first, gradually widened from top to bottom, of the levator ani Affixed to the levator ani muscle after the muscle and then gradually narrow down the inside of their performance in the MRI, in TIWI, T2WI showed on both perirectal fat signal. Mesorectum department of membrane bending strip visible blood vessels, lymph vessels, and round, oval, film and lymph vessels video section, MRI showed round or oval, low signal cable strip.Mesorectal fascia In biopsy and autopsy, mesorectal fascia is the visceral pelvic fascia, formed around the mesorectal fascia clear boundary layer structure. In the above, mesorectal fascia at the level of S3 sacral roots extend to the sigmoid colon mesentery connective tissue. In the following, mesorectal fascia, the fascia extend across the surface of the basin of loose connective tissue, close to the end with the rectal wall, and finally attached to the outer edge of the levator ani, the equivalent of about 2cm below the coccyx at the tip of the former. In MRI, the whole show mesorectal fascia, axial scanning range from S1 to the anus; sagittal scanning range in the femoral head between the medial border of the two tangent; coronal scanning range of the pubic symphysis to the posterior margin of the sacrum Between;. As with the mesorectal fascia and mesangial outside the presence of fat, so that the formation of natural and mesorectal fascia contrast, in the performance on both T2WI TIWI and around the mesorectum as linear low signal structure. In the sagittal end of the mesorectal fascia and the rectal wall close, very little fat between the two, combined with limited spatial resolution 1.5TMR, our cutting-edge as a location mark the coccyx to the coccyx tip as a starting point, along the rectum Traveling down the measure to the direction of 2cm at the rectal wall, as the end of mesorectal fascia attachment.2.①MRI scan showed 49 cases of colorectal tumor exact location, shape; tumor showed intermediate signal signal T1WI, T2WI showed equal or slightly higher signal. MR form and position of the tumor with surgery and pathology results are consistent.②The extent of tumor invasion by the order from light to heavy divided into the following four signs:Tumor signal confined to the intestinal wall, fat and intestine week structured interface; tumor intestinal wall into the mesorectal signal a breakthrough, the wall can be seen outside the bar cable video, film -Like and nodular low signal; tumor signal violations mesorectal fascia, adjacent tissues and organs were normal signal change; tumor signal violations through mesorectal fascia adjacent tissues and organs. MR showed the extent of local tumor invasion and pathological results were different, to determine whether the tumor is the major breakthrough occurred in the intestinal wall, part of the break wall MR showed the tumor, pathological results for the inflammatory reaction around the tumor proliferation.③Pathology results showed that CRM (+) 20, CRM (-) 29, MRI can correctly judge the 45 cases to determine the overall accuracy of 91.8%(45/49),2 cases of CRM (-) before surgery error Sentenced for the CRM (+),2 casesCRM (+) before surgery mistaken for CRM (-).④The lower edge of the tumor, the Department of membrane lymph node cancer nest or increase the distance from the anal verge measured on sagittal MRI measurement of 39 cases on the middle and lower rectal tumor distance from the anal margin, the results compared with the pathological measurements:MRI to determine tumor From the anal margin of the lower edge of the average distance of 6.36± 0.91cm; after the lower edge of the tumor measured the average distance from the anal margin of 7.32±0.42cm. Paired t test, t value 4.35, P value of 0.243, P> 0.05, the difference was not statistically significant.⑤metastatic lymph nodes within the mesorectum and pelvic lymph node metastatic performance of different MRI, normal lymph nodes, metastatic lymph nodes, and reactive lymph node hyperplasia in diameter and shape, are overlapping in the performance of DWI, MRI the performance of the same. In addition, metastatic lymph nodes is important to determine the location of metastatic lymph nodes on the position of circumferential resection margin status, whether the line of sphincter preserving surgery.⑥DCE-MRI:Dynamic contrast-enhanced MRI scan Cancer 49 cases. Lesions were mostly significantly enhanced, regular or irregular edges, some edge of nodular lesions, small pieces or lobulated, homogeneous degree of enhancement within the lesions or uneven. Dynamic enhanced MRI showed enhancement effect of the intestinal wall, but can not distinguish between the intestinal wall layers, especially in mucosa and submucosa. Shows the tumor more clearly than the plain, outline, plain more apparent. However, the extent of tumor invasion to determine the accuracy of the range was no significant increase compared with plain, because the dynamic contrast-enhanced scans can not distinguish between the intestinal wall layers, In addition, some inflammatory reaction around the tumor or vascular lesions such as hyperplasia also showed enhanced effects of change, so Determine the scope of tumor invasion was no significant increase accuracy.TIC curve is divided into three types:A type-speed lift platform type; B-type-type of fast down hill; C type-rise type. Cancer and normal the intestinal wall tissue compared TIC parameters:rectal cancer compared with normal mucosa, reaching peak signal intensity (SImax), after injection of contrast agent before the lmin the largest signal strength (SI1min) peak time (Tpeak), the early enhancement ratio (SIR) were higher than those of normal rectal the intestinal wall, SImax and SI1min, early enhancement rate P value less than 0.05, there are statistically significant. Tumor peak time (Tpeak) less than the normal peak time of the intestinal wall, there is significant difference between the two. Summary:1.1.5T MRI the T2WI divided the rectum wall into two-layer structure, which ring the mucosa and submucosa showed high signal, the inherent circular muscular layer and coating layer showed a low signal. Can not distinguish between mucosa and submucosa, muscularis propria and the coating layer. Mesorectal fascia in TIWI and can be displayed on T2WI, showing around the mesorectum linear low signal structure. MRI can be fully displayed mesorectal fascia.2. FSE T2WI is the best sequence to show the rectal the intestinal wall, the mesorectum and mesorectal fascia. Axial shows mesorectal fascia throughout the scanning range from S1 to the anal verge, sagittal scan range of femoral head between the medial border of the two tangential or coronal to the pubic symphysis to sacrum between the posterior edge. Sagittal MRI scans, providing the end and the adjacent mesorectal anatomy and pathological changes in the organizational structure of information.3. The neoplasms exact location, shape, degree of local tumor invasion can be shown by 1.5TMR, and between the degree of local tumor invasion on MRI and pathological results show differences, to determine whether the tumor is the major breakthrough occurred in the the intestinal wall.4.1.5T MRI in determining the status of circumferential resection of the original has important clinical value in the diagnosis of mesorectum and pelvic lymph node metastases exist difficulties in the feasibility of sphincter preserving surgery, sagittal MRI of rectal cancer to determine the next off The distance from the anal margin edge has a good predictive value, and by the end of the mesorectum and the assessment of surrounding structures, clinical specify a reasonable treatment.5. DCE-MRI can show not only the morphological characteristics of lesions, but also a more comprehensive description of contrast agent to enter and discharge dynamic processes of tumor blood flow, reflecting the focus of local blood circulation, but can not distinguish between the rectal wall layers. Objective:To evaluate routine MRI, routine MRI+high-resolution MRI, routine MRI+high-resolution MRI+DCE-MRI and routine MRI+DWI four inspection methods i reliability in preoperative T, N stage of rectal carcinoma, explore the local staging of rectal cancer (T, N) the best combination of MRI scan sequence.Materials and Methods:1. Study information with the first part of the same patient group.2. Inspection means and the first part of MR parameters and consistent.3. The 49 patients in different series combination of MRI images into four groups, namely, routine MRI, routine MRI+high-resolution MRI, routine MRI+ high-resolution MRI+DCE-MRI for the three groups T, N stage assessment, routine MRI+DWI Only for N staging evaluation.5 years of work by two or more physicians diagnose abdominal imaging method using double-blind review films, respectively, from the four combinations of image sequences preoperative staging (T, N), on routine MRI+DWI N points from the image Period. To the pathological staging as the gold standard, the four inspection methods to evaluate the T, N staging accuracy.4. Statistical analysis using statistical software SPSS 17.0, calculating inspection methods combinations of four sequences of T, N staging accuracy and consistency of the results with the pathological examination, if the Kappa value is less than 0.45, indicating the degree of consistency is poor, if Kappa0.45-0.7 shows moderate consistency can be a general assessment, Kappa values greater than 0.7, indicating a good degree of consistency.Results:Routine MRI, routine MRI+high-resolution MRI, routine MRI+ high-resolution MRI+DCE-MRI scan of three MRI T staging accuracy of rectal cancer were 79.6%,87.8%,89.8%, consistent with the pathological Comparison of Kappa values were 0.650,0.790,0.824; routine MRI, routine MRI+high-resolution MRI, routine MRI+high-resolution MRI+DCE-MRI and routine MRI+DWI inspection methods on the four preoperative N staging of rectal cancer Accuracy was 69.4%,79.6%,81.6%,81.6%, compared with postoperative pathologic findings consistent Kappa values were 0.452,0.616,0.665,0.666. The results show that for T staging, conventional MRI+high-resolution MRI, routine MRI+high-resolution MRI+DCE-MRI sequences of these two high accuracy for N staging, conventional MRI+high-resolution MRI+DCE-MRI and routine MRI+DWI higher accuracy of the two sequences. MRI T staging of overvalued and undervalued, this group of patients showed over-due for some inflammation, infection and vascular disease, resulting in the intestinal wall and surrounding structures produce similar signs of tumor invasion, leading to over-staging. Underestimated because of the tumor within the mesorectum micrometastases, can not exactly show the MRI, leading to inadequate staging. Dynamic enhanced MRI can not distinguish between layers of the intestinal wall, mucosa and submucosa mucosa in particular, the other part of the inflammatory reaction around the tumor or vascular lesions such as hyperplasia showed strengthening effect change, produce similar signs of tumor invasion. Therefore, the tumor was no significant increase the accuracy of T staging.Summary:1. Routine MRI+high-resolution MRI+DWI sequence combination that is the local staging of rectal cancer MRI (T, N) the optimal sequence alignment. routine MRI+ high-resolution MRI T staging accuracy rate of 87.8%, conventional MRI+DWI N staging accuracy rate of 81.6%.2. For N staging of rectal cancer, not only to determine the number of lymph nodes, but also the use of MRI images of different scanning position to determine the spatial location of lymph nodes, to understand their relative position with the mesorectal fascia, especially the use of sagittal images, understand the mesorectum End of the lymph node metastasis has important clinical significance.3. DCE-MRI does not improve cancer T, N stage 1. Routine MRI+high-resolution MRI+DWI sequence combination that is the local staging of rectal cancer MRI (T, N) the optimal sequence alignment.2.1.5T MRI the T2WI divided the rectum wall into two-layer structure, the mucosa and submucosa, muscularis propria and the coating layer, can not distinguish between mucosa and submucosa, muscularis propria and the coating layer. Circumferential resection margin in determining the original state has an important clinical value. In determining the metastatic lymph nodes as being difficult.3. Sagittal T2WI mesorectal fascia can be fully displayed, the lower edge of the tumor to determine the distance from the anal margin, while also using sagittal MRI shows mesorectal anatomy and pathological changes of the end of the surgical treatment of rectal cancer has important clinical value.4. MRI of rectal carcinoma with high accuracy, T stage of N staging accuracy is low.5. DCE-MRI does not improve cancer T, N stage. |
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