Colorectal neoplasm:Magnetic resonance colonography with fat enema-initial clinical experience

AIM： To assess Magnetic resonance colonography with fat enema as a method for detection of colorectal neoplasm.METHODS： Consecutive twenty-two patients underwent MR colonography with fat enema before colonoscopy. Tl-weighted three-dimensional fast spoiled gradient- echo with inversion recovery sequence was acquired with the patient in the supine position before and 75 s after Gadopentetate Dimelumine administration. Where by, pre and post MR coronal images were obtained with a single breath hold for about 20 s to cover the entire colon. The quality of MR colonographs and patients＇ tolerance to fat contrast medium was investigated. Colorectal neoplasms identified by MR colonography were compared with those identified on colonoscopy and sensitivity of detecting the lesions was calculated accordingly.RESULTS： MR colonography with fat enema was well tolerated without sedation and analgesia. 120 out of 132 （90.9%） colonic segments were well distended and only 1 （0.8%） colonic segment was poor distension. After contrast enhancement scan, mean contrast-to-noise ratio （CNR） value between the normal colonic wall and lumen was 18.5 ± 2.9 while mean CNR value between colorectal neoplasm and lumen was 20.2± 3.1. By Magnetic resonance colonography, 26 of 35 neoplasms （sensitivity 74.3%） were detected. However, sensitivity of MRC was 95.5% （21 of 22） for neoplasm larger than 10 mm and 55.6% （5 of 9） for 5-10 mm neoplasm.CONCLUSION： MR colonography with fat enema and Tl-weighted three-dimensional fast spoiled gradientecho with inversion recovery sequence is feasible in detecting colorectal neoplasm larger than 10 mm.

Colonography by CT,MRI and PET/CT combined with conventional colonoscopy in colorectal cancer screening and staging

Colorectal cancer (CRC) remains a leading cancer killer worldwide. But the disease is both curable and preventable at an early stage. Regular CRC cancer screening has been shown to reduce the risk of dying from CRC. However, the importance of large-scale screening is only now starting to be appreciated. This article reviews a variety of imaging procedures available for detecting ulcerative colitis (UC) and Crohn's disease (CD), polyps and CRC in their early stage and also presents details on various screening options. Detecting, staging and re-staging of patients with CRC also require multimodality, multistep imaging approaches. Staging and re-staging with conventional colonoscopy (CC), computer tomography colonography (CTC), magnetic resonance colonography (MRC) and positron emission tomography/computer tomography colonography (PET/CTC) are of paramount importance in determining the most appropriate therapeutic method and in predicting the risk of tumor recurrence and overall prognosis. The advantages and limitations of these modalities are also discussed.

Bimodal visualization of colorectal uptake of nanoparticles in dimethylhydrazine-treated mice

AIM:To investigate colorectal uptake of solid lipid nanoparticles(SLNs) in mice receiving different doses of 1,2-dimethylhydrazine(DMH) using magnetic resonance(MR) and laser-scanning confocal fluorescence microscope(LSCFM) imaging.METHODS:Eight mice were sacrificed in a pilot study to establish the experimental protocol and to visualize colorectal uptake of SLNs in normal mice.Gadopentetate dimeglumine and fluorescein isothiocyanate(FITC)-loaded SLN(Gd-FITC-SLN) enemas were performed on mice receiving DMH for 10 wk(group 1,n = 9) or 16 wk(group 2,n = 7) and FITC-SLN enema wasperformed on 4 DMH-treated mice(group 3).Pre-and post-enema MR examinations were made to visualize the air-inflated distal colorectum.Histological and LSCFM examinations were performed to verify colorectal malignancy and to track the distribution of SLNs.RESULTS:Homogeneous enhancement and dense fluorescence(FITC) deposition in colorectal wall were observed in normal mice and 1 DMH-treated mouse(group 1) on fluid attenuated inversion recovery(FLAIR) and LSCFM images,respectively.Heterogeneous mural enhancement was found in 6 mice(4 in group 1;2 in group 2).No visible mural enhancement was observed in the other mice.LSCFM imaging revealed linear fluorescence deposition along the colorectal mucosa in all groups.Nine intraluminal masses and one prolapsed mass were detected by MR imaging with different enhancement modes and pathologies.Interstitial FITC deposition was identified where obvious enhancement was observed in FLAIR images.Bladder imaging agent accumulations were observed in 11 of 16 DMH-treated mice of groups 1 and 2.CONCLUSION:There are significant differences in colorectal uptake and distribution of SLNs between normal and DMH-treated mice,which may provide a new mechanism of contrast for MR colonography.

Virtual gastrointestinal colonoscopy in combination with large bowel endoscopy:Clinical application

Although colorectal cancer (CRC) has no longer been the leading cancer killer worldwide for years with the exponential development in computed tomography (CT) or magnetic resonance imaging, and positron emission tomography/CT as well as virtual colonoscopy for early detection, the CRC related mortality is still high. The objective of CRC screening is to reduce the burden of CRC and thereby the morbidity and mortality rates of the disease. It is believed that this goal can be achieved by regularly screening the average-risk population, enabling the detection of cancer at early, curable stages, and polyps before they become cancerous. Large-scale screening with multimodality imaging approaches plays an important role in reaching that goal to detect polyps, Crohn's disease, ulcerative colitis and CRC in early stage. This article reviews kinds of presentative imaging procedures for various screening options and updates detecting, staging and re-staging of CRC patients for determining the optimal therapeutic method and forecasting the risk of CRC recurrence and the overall prognosis. The combination use of virtual colonoscopy and conventional endoscopy, advantages and limitations of these modalities are also discussed. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.