Effect of using endorectal coil in preoperative staging of rectal carcinomas by pelvic MR imaging
Introduction
Rectal cancer is a highly treatable disease, with combined surgery and adjuvant or neoadjuvant therapy resulting in cure in 50% of patients. Therefore, preoperative staging is important to identify patients for selected treatment and those who are likely to benefit from adjuvant or neoadjuvant therapy. Patients whose tumors are confined within the rectal wall (T1, T2) can be offered a local surgical procedure, and those with involvement of the perirectal fat or lymph nodes can be offered preoperative adjuvant therapy in order to decrease the bulk of tumor and improve the chance of complete surgical resection. In Europe, preoperative radiotherapy or radiochemotherapy is the preferred approach to tumor of middle or lower rectum, whereas in United States, adjuvant therapy consisting of combined postoperative radiochemotheraphy is favored for patients with T3 and/or N1 [1], [2], [3], [4]. A number of imaging techniques are now available for staging primary tumor: endorectal ultrasound (US), computed tomography (CT) and magnetic resonance (MR) imaging. The accuracy for staging of tumor penetration by endorectal ultrasound ranges from 64% to 95%, with an average of 84%. However, accuracy rates are influenced by operator experience and level of the tumor. In addition, peritumoral inflammation may cause overstaging, and placing the probe is mostly discomfortable and sometimes impossible for stenotic tumors [5], [6]. Role of CT in local staging has diminished with the advent of transrectal ultrasound and MRI due to its inability to distinguish rectal wall layers and the lack of true multiplanar imaging capability [7]. Lately, in a study comparing conventional CT and MDCT, it was shown that multidetector CT (MDCT) was superior to conventional CT in the evaluation of depth of tumor invasion; however, both modalities similarly showed modest diagnostic accuracy in the evaluation of lymph node metastasis [8]. Another preliminary study demonstrated that MDCT is equally accurate in the preoperative staging of locally advanced rectal carcinoma when compared with MRI [9]. More comparative contemporary data are awaited in this context. Results of the studies show varying accuracy rates for preoperative staging by MRI with either phased-array coil or endorectal coil. Some of the authors believe that introduction of endorectal coil has improved resolution and revealed better accuracy rates for staging rectum cancer, whereas others suggest that endorectal coil should be abandoned due to its inability to provide any further information to the images obtained by phased-array coil [10], [11].
In this study, the images obtained by pelvic phased-array coil alone and after the endorectal coil was placed were reviewed and correlated with histopathologic findings of the surgical specimens. Retrospectively, the imaging before and after endorectal coil placement were compared to figure out if endorectal coil imaging can contribute to pelvic imaging in routine examinations and its disadvantage of causing discomfort can be overlooked in consideration of more accurate results for staging rectal carcinoma.
Section snippets
Patient population
From January 2003 to November 2003, 33 patients (20 male, 13 female; mean age, 62; age range, 32–77) who had rectal carcinoma on CT scan or rectosigmoidoscopy were prospectively enrolled to the study. Five of these patients were determined as inoperable based on imaging findings and surgical consultation and suggested having preoperative chemoradiotherapy and three of them were excluded as they could not tolerate the placement of the endorectal coil. Two patients had stenosing lesions,
Results
The distance of the tumor to the anal verge was 2–10 cm (mean distance 5.5 cm). Tumor sizes ranged between 2 cm × 0.5 cm to 6 cm × 3 cm (mean, 3 cm × 2.5 cm). The rectal segment affected by tumor was measured as 1–6 cm in length. Histopathological comparison of T staging of the tumors diagnosed by MR imaging is shown in Table 5. The sensitivity, specificity and accuracy of MRI in staging of T3 tumor were 71%, 100% and 84%, respectively, on both images obtained by pelvic phased-array coil alone and with the
Discussion
As there are very different therapeutic strategies required for operable localized disease and locally advanced or disseminated disease, preoperative staging is indicated in almost all circumstances [14]. This is important for both the early stage and advanced stage carcinoma. Most early carcinomas of the colon and rectum can be treated by adequate local excision, such as colonoscopic polypectomy and per-anal excision. If there are adverse risk factors, especially poorly differentiated
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2020, Clinical ImagingCitation Excerpt :RC staging before surgery is presently based on the findings of computed tomography (CT), endoscopic ultrasound (EUS), and magnetic resonance imaging (MRI), even though it is not possible to accurately assess the HG and extent of LNM by imaging alone because CT has poor soft-tissue contrast and nonspecific size criteria [3,4], while EUS is limited by technical inadequacies in detecting stenotic tumors, extraordinary operator reliance, interface echoes caused by artifacts, and an inadequate sonographic range [5–7]. Although conventional MRI is used as an alternative to CT and EUS [8–10], MRI is also an insufficient means by which to assess the HG and extent of LNM in RC [11–20]. Previous studies have shown that the apparent diffusion coefficient (ADC) has the potential to predict the HG of RC; however, the differentiation of RC HG based on ADC was reported to be difficult because of the considerable overlap of ADC values [21–23].
Colorectal carcinoma: Ex vivo evaluation using 3-T high-spatial-resolution quantitative T2 mapping and its correlation with histopathologic findings
2017, Magnetic Resonance ImagingCitation Excerpt :In contrast to the abovementioned modalities, some reports have suggested the ability of magnetic resonance (MR) imaging in depicting mural invasion by colorectal carcinomas [8,9]. However, conventional MR imaging, which features limited spatial resolution, cannot distinguish individual colorectal wall layers [10–16]. To overcome this limitation as well as the visual and subjective nature of MR assessment, 1.5-T quantitative T2 mapping has been recommended for providing more objective assessments of rectal and prostate tumors [17,18].
Optimizing Adjuvant Treatment Decisions for Stage T2 Rectal Cancer Based on Mesorectal Node Size. A Decision Analysis
2013, Academic RadiologyCitation Excerpt :We accounted for the possibility of incorrect T2 staging of the primary tumor at MRI as follows. Tumors incorrectly staged as T2 at MRI are most often T3 at pathology; incorrect staging of T2 tumors as T1 or T4 is less common (11,15,18–23). Thus, in our model, a clinically staged T2 tumor at MRI could either be a T2 (true T2) or a T3 (false T2) tumor at pathology.
Magnetic Resonance Imaging of Anorectal Neoplasms
2009, Clinical Gastroenterology and HepatologyCitation Excerpt :In recent times, rectal cancer has become a treatable condition. Curative surgery is possible in 50% of cases, with a combination of surgery and adjuvant or neoadjuvant therapy.28 Recurrence rate after TME alone is less than 10%, whereas recurrence rates of 3%–32% have been reported after curative resection of the rectum for rectal cancer.29–32
Staging and Diagnostics of Rectal Cancer
2023, Zentralblatt fur Chirurgie - Zeitschrift fur Allgemeine, Viszeral- und Gefasschirurgie
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