Three-dimensional MR and axial CT colonography versus conventional colonoscopy for detection of colon pathologies

AIM： To evaluate the sensitivity and specificity of MR colonography （MRC） and CT performance in detecting colon lesions, and to compare their sensitivity and specificity with that of conventional colonoscopy. METHODS： Forty-two patients suspected of having colonic lesions, because of rectal bleeding, positive fecal occult blood test results or altered bowel habits, underwent the examinations. After insertion of a rectal tube, the colon was filled with 1000-1500 mL of a mixture of 9 g/L NaCI solution, 15-20 mL of 0.5 mmol/L gadopentetate dimeglumine and 100 mL of iodinized contrast material. Once colonic distension was achieved, three-dimensional gradient-echo （3D-GRE） sequences for MR colonography and complementary MR images were taken in all cases. Immediately after MR colonography, abdominal CT images were taken by spiral CT in the axial and supine position. Then all patients were examined by conventional colonoscopy （CC）. RESULTS： The sensitivity and specificity of MRC for colon pathologies were 96.4% and 100%, respectively. The percentage of correct diagnosis by MRC was 97.6%. The sensitivity and specificity of CT for colon pathologies were 92.8%, 100%, respectively. The percentage of correct diagnosis by CT was 95.2%. CONCLUSION： In detecting colon lesions, MRC achieved a diagnostic accuracy similar to CC. However, MRC is minimally invasive, with no need for sedation or analgesics during investigation. There is a lower percentage of perforation risk, and all colon segments can be evaluated due to multi-sectional imaging availability; intramural, extra-intestinal components of colonic lesions, metastasis and any additional lesions can be evaluated easily. MRC and CT colonography are new radiological techniques that promise to be highly sensitive in the detection of colorectal mass and inflammatory bowel lesions.

The added clinical value of performing CT colonography in patients with obstructing colorectal carcinoma

Background:A small percentage of incomplete optical colonoscopies(OCs)are the result of an obstructing tumor.According to current guidelines,CT colonography(CTC)is performed to prevent missing a synchronous tumor.The aim of this study was to evaluate how frequently a synchronous tumor was found on CTC and how often this led to a change in the surgical plan.Methods:In this retrospective study,a total of 267 patients underwent CTC after an incomplete OC as a result of an obstructing colorectal carcinoma(CRC).Among them,210 patients undergoing surgery met the inclusion criteria and were included in the analysis.The OC report,CTC report and surgical report of these patients were retrospectively evaluated for the presence of synchronous tumors using surgery and post-operative colonoscopy as the gold standard.Results:Six of the 210 patients(2.9%)showed signs of a synchronous CRC proximal to the obstructing tumor on CTC.In three of these patients,a synchronous CRC was confirmed during surgery.All these tumors caused a change in the surgical plan.Three out of the six tumors found on CTC were found to be large,non-malignant polyps.All these polyps were located in the same segment as the obstructing tumor and therefore did not alter the surgical plan.Conclusion:In patients with obstructing CRC,the frequency of synchronous CRCs proximal to this lesion is low.Performing a CTC leads to a change in surgical plan based on the presence of these synchronous tumors in 1.4%of the cases.CTC should be employed as a one-stop shop in patients with an obstructing CRC.

Optimal Noninvasive Colon Cancer Screening Modality in Patients Not Receiving Colonoscopy

Colon cancer is the third most common among cancer deaths in the US for both men and women. The incidence of colonoscopy has been soaring in younger patients, which led to changes in recent United States Preventive Services Task Force (USPSTF) guidelines to reduce the age for screening from 50 years to 45 years. Demand for colonoscopy services is surging due to increased incidences of colorectal cancer (CRC) in the both aging and younger population. Increased referrals have led to an insufficient workforce in hospitals and long waiting lists. Further, results from colonoscopy reveal a low percentage of CRC or another severe bowel disease (SBD). Therefore, colon cancer screening is a growing concern, particularly in patients who otherwise have a very long-life expectancy, and who are most likely to benefit from screening. Another reason to boost CRC screening is to minimize the load on hospitals by reducing the patients that undergo colonoscopy unnecessarily because only a low percentage of CRC occurrence is observed in individuals undergoing colonoscopy. In recent years, there are a variety of screening options available for CRC. Noninvasive alternatives include fecal immunochemical test (FIT), multitarget stool DNA testing (MT-sDNA, available under the brand name Cologuard), computed tomography (CT) colonography (previously called virtual colonoscopy), guaiac-based fecal occult blood testing (gFOBT), and capsule colonoscopy (CC). These tests have varied the degree of evidence supporting their use. This study focuses on the most recent survey and efficacy of noninvasive methods to prevent and detect colorectal cancer (CRC).