|Year : 2014 | Volume
| Issue : 3 | Page : 98-102
Preoperative evaluation of colorectal carcinoma by multislice computed tomography
Aly A Elbarbary, Manal E Badawy
Department of Radiodiagnosis, Faculty of Medicine, Tanta University, Tanta, Egypt
|Date of Submission||25-Apr-2014|
|Date of Acceptance||06-Jul-2014|
|Date of Web Publication||29-Oct-2014|
Aly A Elbarbary
MD, Radiodiagnosis Department, Faculty of Medicine, Tanta University, Saeed Street, Tanta
The purpose of this study was to assess the role of multislice computed tomography (MSCT) in preoperative evaluation of colorectal carcinoma (CRC) and to compare the imaging findings with surgical/pathological findings.
Patients and methods
MSCT scan was performed for 44 patients with pathological proven CRC. All these patients underwent spiral computed tomography with oral and intravenous contrast administration. Surgery was subsequently performed in all patients and surgical specimens were sent for detailed pathologic analysis. The MSCT assessment was then compared with the histopathological findings for sensitivity, specificity, and accuracy.
MSCT had 60% sensitivity and 83% specificity for assessment of local spread of disease, 69% sensitivity and 76% specificity for the evaluation of lymph nodal metastases, and 89% sensitivity and 96% specificity for hepatic metastases. In all cases, the visualized tumor growth with wide zone of resection and regional nodal chains were surgically removed. It was, however, the distant metastases that made a difference to the type of curative or palliative surgery planned, and in this study spiral computed tomography had 92% accuracy for detection of hepatic metastases.
MSCT has a significant role in preoperative evaluation and subsequent management of CRC.
Keywords: Colonic carcinoma, multislice computed tomography, rectal carcinoma
|How to cite this article:|
Elbarbary AA, Badawy ME. Preoperative evaluation of colorectal carcinoma by multislice computed tomography. Tanta Med J 2014;42:98-102
|How to cite this URL:|
Elbarbary AA, Badawy ME. Preoperative evaluation of colorectal carcinoma by multislice computed tomography. Tanta Med J [serial online] 2014 [cited 2020 Nov 29];42:98-102. Available from: http://www.tdj.eg.net/text.asp?2014/42/3/98/143562
| Introduction|| |
Colorectal carcinoma (CRC) is the third common malignancy worldwide and is one of the common causes of cancer-related death ,. Preoperative evaluation of the extent of CRC spread indicates the expected prognosis and also assists management .
CRC is usually diagnosed by barium studies and colonoscopy followed by biopsy. Although these techniques provide excellent visualization of the mucosa, they cannot determine the depth of mural invasion by the tumor or the extent of metastatic disease. In patients with CRC, accurate assessment of tumor extent within and beyond the bowel wall, the presence or absence of lymphadenopathy, and distant metastases are significantly important .
The depth of bowel wall invasion and presence of lymph node metastases and distant metastases are the major factors that affect the prognosis of patient . All patients with CRC were staged on multislice computed tomography (MSCT) according to the modified tumor, node, metastasis (TNM) classification. Modified computed tomographic (CT) criteria were adapted from Burton et al.  and Hennedige et al. .
Accurate staging of CRC is important to provide the optimal treatment strategy. Despite preoperative evaluation and staging of CRC patient is difficult, CT scanning has been very often used in preoperative staging of CRC as a noninvasive instrument with the development of high resolution scanners, technical refinements in obtaining better quality as a result. CT is an excellent imaging tool for screening the distant metastases ,,.
Advances in CT technologies have increased interest in the potential role of multidetector computerized tomography (MDCT) for detection and staging of CRC .
The aim of this study was to assess the role of MSCT in preoperative evaluation of CRC and to compare the imaging findings with surgical/pathological findings.
| Patients and methods|| |
Between March 2012 and November 2013, 44 patients with biopsy-proved CRC were prospectively included in this study (24 men, 20 women with an age range of 30-79 years and mean age of 61.7 years). Of the 44 patients who had a prior colonoscopy, seven patients had incomplete application due to inability to pass a distal stricture. All patients were operated upon within 3 weeks after CT examination. Patients who had received any prior treatment for CRC or those who had any concurrent disease process, which could result in a false interpretation of the CT scan, were excluded; in addition, patients with chronic renal impairment (high serum creatinine >2 mg/dl) or previous allergy to the contrast media were excluded from the study. This study was approved by the ethics committee of our institution; informed consent was obtained from all patients after full explanation of the benefits and risks of the procedure.
| Methods|| |
All patients received 800-1000 ml of water as oral contrast medium 6 h before the scan. Automatic injection of 100 ml nonionic iodinated contrast omnipaque300 (containing 300 mg of iodine per ml, Omnipaque; Schering, USA) was given at a rate of 5 ml/s into the antecubital vein. MDCT examinations were performed for all patients using a 16-detector CT scanner (Somatom, E-motion 16; Siemens Healthcare, Germany). The acquisition parameters were 120 kVp, 350 mAs, a helical pitch of 1.375 : 1, 0.6 s gantry rotation time, table speed of 53 mm/rotation, 0.625-mm-detector configuration, 18.4 s total exposure time, 0.625 mm helical slice thickness, and 0.625 mm reconstruction interval with a large field of view. The axial source images with a 0.625 mm slice were transferred to a dedicated workstation (Wizard; Siemens Healthcare). Images were acquired from above the dome of diaphragm to the pubic symphysis in craniocaudal manner. Scanning was initiated in spiral mode 45-50 s after the initiation of intravenous contrast injection. Images were acquired in venous phase of enhancement, which is ideal for detection of hepatic metastases, majority of which are hypovascular. Imaging was performed in two or three breath-holds in majority of patients.
For the location of each lesion, the large intestine was divided into eight anatomic segments: cecum, ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon, and rectum. One experienced gastrointestinal radiologist with more than 5 years of experience reviewed the images. The reader identified the location of the cancer, extent of local invasion, lymph node spread, and adjacent or distant organ involvement. The MSCT staging criteria had been used for local tumor spread, lymph node involvement, and distant metastasis [Table 1] and [Table 2]. The radiological assessment was then compared with the surgical and histopathological findings. Pathological staging was performed according to the TNM classification described by the American Joint Committee on Cancer (AJCC) for CRC.
|Table 1: Multislice computed tomography criteria for tumor staging, modifi ed from Burton et al.  and Hennedige et al. |
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|Table 2: Multislice computed tomography criteria for nodal and metastases staging, modifi ed from Burton et al. 6] and Hennedige et al. |
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Sensitivity, specificity, and accuracy were calculated for TNM staging from MDCT image results. Differences in accuracy for N and T staging and also differences in accuracy for the locations of T and N staging were assessed by the χ2 -test and related-samples marginal homogeneity tests. SPSS 19.0 software, USA, was used for statistical tests.
| Results|| |
A total of 44 patients were included in the study (24 men and 20 women). According to localization, 17 tumors were localized in the right colon [cecum (n = 8), ascending colon (n = 3), hepatic flexure (n = 2), and transverse colon (n = 4)], 27 tumors were localized in the left colon [splenic flexure (n = 2), descending colon (n = 2), sigmoid colon (n = 14)], and nine tumors were localized in the rectum. The clinical presentation in majority of cases was abdominal pain (32%) and altered bowel habits (30%). The other symptoms included weight loss and bleeding per rectum in 22% patients, a palpable mass in one patient, and one patient had no symptoms.
MSCT for the assessment of all phases of the tumor, nodal, and metastases stages was measured separately for the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy [Table 3],[Table 4] and [Table 5].
|Table 3: Multislice computed tomography assessment of all phases of tumor stages (Balthazar et al. )|
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|Table 4: Multislice computed tomography assessment of all phases of nodal stages|
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|Table 5: Multislice computed tomography assessment of all phases of metastases stages|
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Evidence of local (extramural) spread of the tumor was determined using the help of parameters mentioned in [Table 1]. These were compared with surgical/histological results. Correct assessment for local spread was made in 29 of 44 scans (66%). Incorrect assessment was made in 15 scans (34%). Of the 29 scans correctly evaluated, 22 scans had extramural tumor spread (true positive) and seven scans did not (true negative). Of the 15 CT scans proven to be incorrectly evaluated, local spread was falsely interpreted as positive in two patients and as negative in 13 patients. The sensitivity and specificity of CT scan in detecting local tumor spread in this study was 60 and 83%, respectively. The positive and negative predictive values were 92 and 38%, respectively.
The preoperative evaluation for lymph nodal status was also performed according to the predefined criteria stated in [Table 2]. They were divided into two groups: metastatic lymphadenopathy or no lymphadenopathy detected. Lymphadenopathy was correctly identified in 31 of 44 patients (70%) and incorrectly in 13 of 44 patients (30%). Twenty-three of these 31 scans correctly assessed had histologically proven metastatic lymphadenopathy (true positive). The remaining eight of 31 scans were accurately described as negative for lymphadenopathy (true negative). Of the 13 CT scans proven to be incorrectly evaluated, three patients were falsely interpreted as positive and 10 patients as negative. The sensitivity and specificity for detection of adenopathy was 69 and 76%, respectively. The positive predictive value for metastatic lymphadenopathy was 85% and negative predictive value was 52% [Figure 1],[Figure 2],[Figure 3],[Figure 4] and [Figure 5].
For hepatic metastases, CT scans were correct in evaluation in 41 of 44 scans (93%), with 11 true positives and 30 true negatives. Of the remaining three, one scan was proven to be false positive and two false negative on surgery. Perioperative surgical evaluation was used for confirmation. Furthermore, all patients regardless of the presence or absence of liver metastasis were followed for 1 year in which 6-monthly clinical assessment and ultrasonography were performed. The sensitivity and specificity of preoperative CT for hepatic metastases were proven to be 89 and 96%, respectively. Positive and negative predictive values were 94 and 88%, respectively. Metastases to the lungs were found in two patients. Located on the lung bases, all of these were identified correctly.
| Discussion|| |
Accurate preoperative evaluation of the local staging of CRC is required to predict prognosis and to select most appropriate management. There is no guideline clearly stating an optimal strategy for preoperative imaging .
Advances in CT technology have raised interest in the potential role of CT for detecting and staging of CRCs. With the development of MDCT thin-section images, faster scan acquisitions, improved resolution, and multiplanar reconstruction images have shown better accuracy in T and N staging ,.
The sensitivity of CT detection depends mainly on the size of the colorectal tumor and the quality of the CT examination. Conventional CT has undergone significant changes with the development of MDCT. The prognosis of CRC is directly related to the extent of colorectal wall invasion, lymph node involvement, and distant metastases ,.
In this study, accurate prediction of local spread was made in 65% of patients with a sensitivity and specificity of 60 and 83%, respectively. Balthazar et al.  found an accuracy of 58% in 90 patients. Freeny et al.  examined 103 patients and reported sensitivity of 61% and a specificity of 81% for local tumor extension. Gazelle et al.  correctly assessed 23 of 30 tumors using water as intraluminal contrast. The best-published results, however, are for Hundt et al.  with an accuracy of 81%.
Lymph nodal assessment was accurate for 70% of the patients, the sensitivity and specificity being 69 and 76%, respectively. Balthazar et al.  determined a sensitivity of 73% and a specificity of 46%. The disparity in the results of various authors is most likely related to the different diameter of nodes considered pathologic. If the criterion for nodal size, which is 1 cm, is lowered, the sensitivity increases at the expense of specificity.
Modern surgical opinion helps to solve this universal problem faced by radiologists concerning nodal assessment. It is now accepted that low sensitivity is not a significant clinical problem because regional lymph node sampling is routinely performed at surgery .
CT has an established role in the detection of hepatic metastases. Currently, spiral CT coupled with rapid injection of contrast material is the preferred technique for hepatic imaging and is more sensitive than conventional scanning for tumor detection and characterization. When imaging the liver for metastases, adequate hepatic enhancement is crucial. Using spiral CT, Kuszyk et al.  achieved a sensitivity of more than 90% for detection of liver lesions more than 1 cm in diameter and a sensitivity of more than 56% for detection of lesions smaller than 1 cm. These results represent an improvement over those achieved with traditional incremental CT. The results of this study are equally good with 89% sensitivity and 96% specificity for liver metastases. This study shows that spiral CT has an accuracy of 65% for local spread of CRC, 70% for evaluation of lymphadenopathy, and 92% for hepatic metastases.
| Conclusion|| |
MSCT has a significant role in preoperative evaluation and subsequent management of CRC.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]