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العنوان
Role of MRI in rectal cancer staging /
المؤلف
Abd Alraheem, Mohammed Redia.
هيئة الاعداد
باحث / محمد رضا عبد الرحيم الساعدي
مشرف / أحمد محمد منيب
مشرف / رشا صلاح الدين حسين
الموضوع
Rectum - Cancer.
تاريخ النشر
2017.
عدد الصفحات
141 .p :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
الأشعة والطب النووي والتصوير
تاريخ الإجازة
1/10/2017
مكان الإجازة
جامعة عين شمس - كلية الطب - Radio-diagnosis
الفهرس
Only 14 pages are availabe for public view

from 141

from 141

Abstract

Rectal cancer is one of the most common causes of cancer cases all over the world. Its highest incidence is found in industrialized developed countries and its lowest incidence is found in developing countries.
Adenocarcinomas account for the vast majority (more than 67%) of rectal cancer, mucinous adenocarcinomas account for 20% (most aggressive type).
Despite advances in the diagnosis and treatment of rectal cancer, fiveyear survival rates continue to hover around the 50% mark. For cancers limited to the bowel wall, the survival rate climbs to 83%-90%, and drops to less than 10% if there are distant metastases, highlighting the importance of early detection and treatment.
Treatment is either surgical excision which is the total mesorectal excision (TME) alone (free resection margin) or neoadjuvant therapy followed by TME (involved resection margin).
The MRI protocol was T1W in axial plane, T2W in axial, coronal and sagittal planes, T1W post contrast fat saturation in axial, coronal and sagittal planes and DW-MRI. All cases have undergone surgery and their specimens were sent for histopathological assessment,and these result were used as our gold standerd.
MR imaging of the rectum may be performed with either an endorectal coil or a phased-array surface coil. Use of an endorectal coil yields high resolution images that fully depict the wall layers of the bowels, although clear differentiation between the mucosa and submucosa is still difficult.
The major drawback of endorectal coil MR imaging is difficulty in Evaluating stenosing and high rectal carcinomas. Moreover, a complete assessment of the perirectal structures is rather difficult because portions of the mesorectal fascia, mesorectal fat, and lymph nodes lie outside the field of view; so that evaluation with endorectal coil MR imaging is comparable to that with transrectal sonography.
In our study we used a phased-array surface coil yields high spatial resolution images, thereby providing a full evaluation of the rectal wall layers, and has the additional advantage of a large field of view.
Finally, stenosing lesions and tumors at the rectosigmoid junction can be evaluated in all cases, and the mesorectal fat and mesorectal fascia can be visualized.
The most suitable MR sequence for rectal cancer staging is the T2 weighted image sequence as it best depicts the anatomy of the rectal wall. Proper angulation along the rectal wall at the tumor site leads to accurate detection of tumor stage and its relation to CRM. IV gadolinium, fat suppression are not needed as they do not improve the diagnostic accuracy.
The use of rectal contrast was needed in some cases in this when it is difficult to clarify the relation of the tumor to the rectal. However, rectal contrast causes distension of the lumen making detection of mesorectal LN and CRM involvement difficult.
Our study included 30 patients with preoperatively diagnosed rectal cancer and the mean age was 48.05 (ranges from 26 to 74 years).
All patients have been subjected to pelvic MRI assessment performed on 1.5T magnet with pelvic phased array coil.
We found that the MRI results of 27 out of 30 patients were correct when compared with the histopathological results in different T stages (i.e. accuracy was 90%).
Regarding the differentiation of T2/T3 tumors, the sensitivity, specificity, PPV, NPV and accuracy were 86.30%, 75%, 84%, 89.90% and 81%, respectively.
Regarding the differentiation of T3/T4 tumors, the sensitivity, specificity, PPV, NPV and accuracy were 90.4%, 80%, 93%, 95% and 89%, respectively.
Regarding N staging, we found that the MRI results of 23 out of 30 patients were correct when compared with histopathological results in different N stages (i.e. accuracy was 80.2%).
In the evaluation of mesorectal fat invasion in comparison with histopathological examination, we found that the MRI accuracy was 100%.
In the evaluation of MRF invasion in comparison with histopathological examination results, we found that the MRI accuracy was 96.7%.
In the evaluation of the CRM status in comparison with histopathological examination results, we found that the values of sensitivity, specificity, PPV, NPV and accuracy were 91.7%, 100%, 100%, 94.7% and 96.7%, respectively.
The results of this study demonstrate that preoperative HRMRI has a great value in achieving the best treatment strategy through accurate staging of rectal cancer, prediction of negative CRMs and involvement of the perirectal and pelvic LNs.