Negative Oral Contrast Research Articles

Endoscopic Diagnosis of Small Bowel Tumor.

Recent technological advances, including capsule endoscopy (CE) and balloon-assisted endoscopy (BAE), have revealed that small intestinal disease is more common than previously thought. CE has advantages, including a high diagnostic yield, discomfort-free, outpatient basis, and physiological images. BAE enabled endoscopic diagnosis and treatment in the deep small bowel. Computed tomography (CT) enterography with negative oral contrast can evaluate masses, wall thickening, and narrowing of the small intestine. In addition, enhanced CT can detect abnormalities outside the gastrointestinal tract that endoscopy cannot evaluate. Each modality has its advantages and disadvantages, and a good combination of multiple modalities leads to an accurate diagnosis. As a first-line modality, three-phase enhanced CT is preferred. If CT shows a mass, stenosis, or wall thickening, a BAE should be selected. If there are no abnormal findings on CT and no obstructive symptoms, CE should be selected. If there are significant findings in the CE, determine the indication for BAE and its insertion route based on these findings. Early diagnosis of small intestinal tumors is essential for favorable outcomes. For early diagnosis, the possibility of small bowel lesions should be considered in patients with unexplained symptoms and signs after examination of the upper and lower gastrointestinal tract.

The efficacy of pineapple juice as a negative oral contrast agent in magnetic resonance cholangiopancreatography

The efficacy of pineapple juice as a negative oral contrast agent in magnetic resonance cholangiopancreatography

Combined Use of Negative Oral Contrast and Ranitidine for Magnetic Resonance Cholangiopancreatography: A Randomized Controlled Trial

Abstract Objective Magnetic resonance cholangiopancreatography (MRCP) is a noninvasive imaging modality to study pancreaticobiliary tree. The primary aim of this study was to compare the image quality of MRCP obtained with the use of ferric ammonium chloride (negative oral contrast) with that of combined use of ferric ammonium chloride and ranitidine (administered orally). Secondary aim was to determine the interobserver agreement between the assessing radiologists. Materials and Methods The study was a single-center randomized-controlled trial. The patients were randomized into two groups. One group received ranitidine orally and ferric ammonium chloride (Dexorange) and the other group received only the ferric ammonium chloride. The images were qualitatively analyzed independently by the two blinded radiologists. Two scoring systems were used for grading the diagnostic quality of the images: the gastrointestinal tract signal intensity score (range: 1–4) and the structure visibility score (range: 0–3). The mean score of contrast effect and image effect of the two groups were compared by using Mann–Whitney U test. A p-value < 0.05 was considered statistically significant. Interobserver agreement was studied using Cohen kappa coefficient. Results A total of 93 patients were eligible for the study. Forty-one patients were randomly assigned to the group that received only negative oral contrast and 52 group that received both ranitidine and negative oral contrast. The mean score of the images obtained with using both ranitidine and negative oral contrast was significantly higher when compared with the other group (3.02 vs. 2.7) (p-value = 0.018). However, there was no significant difference in mean structure visualization score of various parts of the pancreaticobiliary system. The interobserver agreement between the two readers in our study was acceptable. Conclusion Combined use of hematinic syrup and ranitidine increases the image quality by improving the suppression of gastrointestinal fluid signal as compared with the use of only hematinic syrup as negative oral contrast.

A novel food-based negative oral contrast agent compared with two conventional oral contrast agents in abdominal CT: a three-arm parallel blinded randomised controlled single-centre trial

BackgroundA negative oral contrast agent (OCA) has been long sought for, to better delineate the bowel and visualise surrounding structures. Lumentin® 44 (L44) is a new OCA formulated to fill the entire small bowel. The aim of this study was to compare L44 with positive and neutral conventional OCA in abdominal computed tomography (CT).MethodsForty-five oncologic patients were randomised to receive either L44 or one of the two comparators (MoviPrep® or diluted Omnipaque®). Abdominal CT examinations with intravenous contrast agent were acquired according to standard protocols. The studies were read independently by two senior radiologists.ResultsThe mean intraluminal Hounsfield units (HU)-values of regions-of-interest (ROIs) for each subsegment of small bowel and treatment group were -404.0 HU for L44, 166.1 HU for Omnipaque®, and 16.7 HU for MoviPrep® (L44 versus Omnipaque, p < 0.001: L44 versus MoviPrep p < 0.001; Omnipaque versus MoviPrep, p = 0.003). Adverse events, only mild, using L44 were numerically fewer than for using conventional oral contrast agents. Visualisation of abdominal structures beyond the small bowel was similar to the comparators.ConclusionsL44 is a negative OCA with luminal radiodensity at approximately -400 HU creating a unique small bowel appearance on CT scans. The high bowel wall-to-lumen contrast may enable improved visualisation in a range of pathologic conditions. L44 showed a good safety profile and was well accepted by patients studied.Trial registrationEudraCT (2017-002368-42) and in ClinicalTrials.gov (NCT03326518).

Optimization of pineapple juice amount used as a negative oral contrast agent in magnetic resonance cholangiopancreatography

To evaluate the potential variability of Manganese (Mn2+) in commercial pineapple juice (PJ) produced in different years and to identify the optimal Mn2+ concentration in the correct amount of PJ to be administered prior to Magnetic Resonance Cholangiopancreatography (MRCP) in order to suppress the gastroduodenal (GD) liquid signal. The Mn2+ concentration in PJ produced in different years was defined using Atomic Absorption Spectrometry. The optimal Mn2+ concentration and the amount of PJ, were estimated in an in-vitro analysis, and were then prospectively tested in a population of patients who underwent MRCP. The results were compared with those achieved with the previous standard amount of PJ used in a similar population. The concentrations of Mn2+ in commercial PJ produced in different years did not differ. A total amount of 150 ml (one glass) of PJ having a high Mn2+ content (2.37 mg/dl) was sufficient for the suppression of the GD liquid signal, despite the additional dilution caused by GD liquids since it led to a final concentration of Mn2+ of 0.5–1.00 mg/dl. The optimized single-dose oral administration of 150 ml (approximately one glass) of PJ having a high Mn2+ concentration prior to MRCP was adequate to guarantee the correct amount of Mn2+ to suppress the GD signal.

Effectiveness of Boiling Method Using Aquadest Solvent in Oolong Tea Extraction Producing Mangenese Particle as a Contrast Media on Magnetic Resonance Cholangiopancreatography (MRCP)

Magnetic Resonance Cholangiography (MRCP) examines the pancreas and ductus billiaris using magnetic resonance imaging with a negative contrast media administered orally. Oolong tea is possible to be an alternative of an oral negative contrast media due to its manganese contained. This study will elaborate on the best method of oolong tea extraction to get the best mangenese substance and its capability to suppress inevitable organs. This is an experimental study with various methods of extraction, which are the maceration method with ethanol solvent, maceration method with aquadest solvent, and boiling method. The whole process includes collecting and preparing plant materials, sample identification, sample processing, extraction, and extract characterization. The manganese level is checked with Atomic Absorption Spectroscopy (AAS) followed by scanning the extracted oolong tea in bottles and MRCP scanning examination. Results showed that manganese level with three different extraction methods is maceration method with ethanol is 1.23 mg/dl, maceration method with aquadest solvent is 0.82 mg/dl, and the extraction using the boiling method with aquadest solvent 0.94 mg/dl, and manufactured tea 1.40 mg/dl respectively. Scanning the extracted oolong tea in bottles showed that the best suppression is on the bottle, which contains extracted oolong tea using a boiling method with aquadest solvent. The image enhancement on MRCP showed that biliary trees are all enhanced using all the extraction methods; however, the best suppression for the stomach and duodenum is using the boiling method with aquadest solvent. The best choice for oolong tea extraction to get the best image to enhance and maximum suppression for disturbing organs is the boiling method with aquadest solvent. For the oolong tea, oral media contrast is to consider the level of manganese substance and its capability to suppress the disturbing organ to provide the best image for MRCP

Jasmine tea as a negative oral contrast agent in magnetic resonance cholangiopancreatography (MRCP)

Fluids of gastrointestinal system produce a high signal in 2D T2 Half-Fourier Acquisition Single-shot Turbo Spin Echo (HASTE) thick-slab MRCP which can overlap the biliary system image. This is the first experimental study use jasmine tea as oral contrast agent and aimed to evaluate it in improving the image quality of MRCP. This study was tested by phantom and healthy volunteers. Different types of tea phantom were tested which then calculated its signal-to-noise ratio (SNR) value and analyzed the manganese content. 15 healthy volunteers performed 2D T2 HASTE thick-slab MRCP scanning before and after administration of jasmine tea with a variation of 3 minutes, 6 minutes and 9 minutes scanning time. Qualitative analysis was carried out by MRCP questionnaire which was examined by radiologist and quantitative analysis was conducted by measuring the contrast-to-noise ratio (CNR) values. After jasmine tea administration, the image information was significantly different and CNR MRCP was increased compared to before giving negative oral contrast agent. The most optimal time to start scanning was 3 minutes after administration of jasmine tea with a volume of 300 ml (0.648 mg/dl manganese). Jasmine tea can be used as an alternative safe natural negative oral contrast agent and can improve MRCP image quality and reduce the intensity of gastrointestinal signals.

The efficacy of pineapple juice as a negative oral contrast agent in magnetic resonance cholangiopancreatography.

BackgroundDuring magnetic resonance cholangiopancreatography (MRCP), the pancreatobiliary ducts can be obscured by the high-intensity signal from the stomach and duodenum. Pineapple juice may be an alternative to commercially available negative contrast agents, but has not been evaluated locally.ObjectivesTo evaluate the efficacy of a local, off-the-shelf pineapple juice preparation as a negative oral contrast agent for MRCP.MethodAn observational, analytical study was conducted during January–December 2017. A 1.5 Tesla MRCP sequence was performed immediately before and after ingestion of 250 mL of a local, commercially-available pineapple juice preparation. Image evaluation was performed by two radiologists with independent, blind assessment of gastric/duodenal signal intensity and biliary /pancreatic duct visibility, before and after pineapple juice.ResultsFifty adult patients (F = 44, 88%) with median age 44 years (IQR: 34.75, 57) were included. After pineapple juice administration, there was significant measured (1661.51 vs. 1409.94, p < 0.01) and perceived (2.16 vs. 2.72, p < 0.01) duodenal signal reduction but no significant change in measured (1081.17 vs. 1044.38, p = 0.34) or perceived (2.73 vs. 2.84, p = 0.14) gastric signal intensity. Visibility of the common bile duct was significantly improved (3.67 vs. 3.86, p < 0.01), whilst that of the main pancreatic duct showed no significant change (2.92 vs. 2.86, p = 0.44).ConclusionThe local pineapple juice preparation used in this study is an effective, affordable and natural negative oral contrast agent for enhancement of MRCP images, and specifically improves visualisation of the common bile duct.

Signal suppressions of grape syrup and grape syrup/lemon aqueous solutions in magnetic resonance cholangiopancreatography using heavily T2-weighted pulse sequence

Abstract Signal suppression of the gastrointestinal tract fluids in magnetic resonance cholangiopancreatography (MRCP) has been performed using various natural and chemical substances with the different MRCP pulse sequences. This study aimed to investigate the signal suppressions of the grape syrup and the grape syrup/lemon aqueous solutions in MRCP using the heavily T2-weighted sequences. For this purpose, the potassium, iron and manganese contents of grape syrup were measured by atomic absorption spectroscopy. The grape syrup and the grape syrup/lemon solutions with the various grape syrup percentages were imaged using the heavily T2-weighted sequences of MRCP such as T2 HASTE thick slab and T2 SPACE. MRCP in the volunteers was performed before and 10 minutes after oral administration of the grape syrup solution. The concentrations of potassium, iron, and manganese in grape syrup were 34.8, 2.4 and 1 mg/l, respectively. The in vitro study showed significantly lower signal to noise ratio using the grape syrup samples comparing to the grape syrup/lemon. The effective signal suppression for the in vitro study and considerable enhancement of negative contrast in the post-contrast MRCP was obtained using a T2 HASTE thick slab sequence. As a conclusion, the grape syrup solution can be used for signal suppression of the gastrointestinal tract fluid in MRCP as an oral negative contrast material. A T2 HASTE thick slab sequence produces suitable contrast in MRCP images using the grape syrup solution.

THE ROLE OF BLACK TEA AND PINEAPPLE JUICE AS NEGATIVE ORAL CONTRASTS ON MAGNETIC RESONANCE CHOLANGIOPANCREATOGRAPHY (MRCP) EXAMINATION

Background: Magnetic resonance cholangiopancreatography examination is a superior examination in the detection of anatomic structures or pathological abnormalities in the human pancreatobiliary system. This examination is recommended to use negative oral contrast which aims to eliminate gastrointestinal signals that are around the pancreatobiliary system which can be a barrier to the visualization of the pancreatobiliary tract. Materials that can be used as oral contrast contrast must be able to survive for a long time in the gastrointestinal tract and contain elements of iron (Fe) and Manganese (Mn). The high Mn content of black and pineapple juice and its abundance need to be explored as contrast oral negative. Purpose: To prove the role of pineapple juice and black tea which are natural ingredients of negative oral contrast in the visualization of the pancreatobiliary system on MRCP examination. Methods: Experimental quasy studies have been carried out on 9 samples prospectively. Each sample underwent MRCP examination with three treatments, namely given black tea, pineapple juice and plain water. The image results from the three treatments were assessed by Radiology Doctors to assess the quality of their image. Results: The results showed that black tea was more effective in providing optimal image results on MRCP examination than pineapple juice and without using oral contrast contrast. The metal content of negative oral contrast can cause magnetic susceptibility which is characterized by the presence of shortening at the time of T2 relaxation. Negative contrast agents affect signal intensity usually by shortening T2 or T2 *, as an effect, areas of concern, especially areas with negative contrast agents will experience darkening. Conclusion: Black tea is effectively used as a negative oral contrat on MRCP examination.

What is the best fruit juice to use as a negative oral contrast agent in magnetic resonance cholangiopancreatography?

To identify, invitro, the best fruit juice to use as oral contrast agent in magnetic resonance cholangiopancreatography (MRCP) and to test, invivo, the best natural juice and the new parameters in MRCP sequences identified invitro. The invitro evaluations consisted of measuring the T2 values of a pure solution of manganese (Mn) and iron (Fe) at different concentrations, measuring the content of Mn and Fe in five commercial juices and their T2 relaxation times, and identifying the optimal juice dilution for suppressing the gastrointestinal fluid signal. The new parameters of MRCP sequences were tested invivo. Manganese alone strongly influenced the shortening of the T2 values (p=0.004). The T2 value with an echo time (TE) of ≥1,000 ms enabled sufficient intestinal fluid suppression in the case of high juice dilution. A flip angle of 90° maximised the differences between the high signal from static fluids, such as the bile and the fluid in the gastrointestinal tract, using fast imaging employing steady-state acquisition (FIESTA) sequences (p<0.001). The shortening of the T2 relaxation time depended only on the Mn concentration. All the commercial juices had an Mn concentration sufficient to suppress the gastrointestinal fluid signal using long TE sequences. The oral ingestion of commercial juice before MRCP was enough to suppress the signal from the gastrointestinal fluids, regardless of its dilution after ingestion. When using FIESTA sequences, a flip angle of 90° allowed the best suppression of gastrointestinal fluid signals.

Oolong tea drink as an alternative to oral negative contrast media in magnetic resonance cholangio pancreatography (MRCP)

Oolong tea drink as an alternative to oral negative contrast media in magnetic resonance cholangio pancreatography (MRCP)

Unusual gastric tumors and tumor-like lesions: Radiological with pathological correlation and literature review.

Although gastric tumors have overlapping radiologic appearances, some unusual tumors may present specific imaging features. Using multidetector computed tomography (MDCT), with water as a negative oral contrast agent and intravenous contrast medium, can provide critical information for the diagnosis of gastric diseases. In addition, MDCT can evaluate the involvement of the gastric wall and extragastric extent of the disease, as compared with gastroenteroscopy and double-contrast upper gastrointestinal study. Regarding lesion location and size, enhancing and growth patterns, presence of calcification or fat, and involvement of the gastric wall and adjacent structures, CT may provide useful information. In this review article, we review the relevant literature and discuss the CT features and the histopathologic findings of different types of gastric lesions. The lesions are divided into benign (glomus tumors, schwannomas, leiomyomas, and lipomas), malignant (gastrointestinal stromal tumors, mucinous carcinomas, lymphomas, and carcinoid tumors), and tumor-like lesions (ectopic pancreas and bezoar). Familiarity with imaging appearances and pathologic findings can help physicians make an accurate diagnosis.

A Low-temperature Manganese Chloride Tetrahydrate Improves the Image Quality of Magnetic Resonance Cholangiopancreatography

Manganese chloride tetrahydrate (MCT) is one of the oral negative contrast agents which is indispensable for imaging of magnetic resonance cholangiopancreatography (MRCP). In this study, improvement of the image quality of MRCP by using low-temperature MCT is verified. All MR imagings were performed using 1.5 T scanner. The T(1) and T(2) values of the different temperature MCTs were measured in the phantom study. Different concentrations of MCT-doped water (30%, 50%, 70%, and 90%) were measured at several temperature conditions (10°C, 15°C, 23°C, 35°C, and 40°C). As a result, the T(1) and T(2) values became larger with a temperature rise. It was more remarkable in low-concentration MCT. Then, 17 healthy subjects were scanned two times with different temperatures of MCT. The MCT of the normal temperature (23°C) and low temperature (10°C) were taken at consecutive 2 days. The contrast between the stomach and the spleen were significantly higher in 2D half Fourier acquisition single shot turbo spin echo (HASTE) images by use of the low-temperature MCT. The contrast between the common bile duct and the adjacent background were significantly higher in the source images of 3D MRCP by use of the low temperature MCT. In addition, 76% of subjects answered in the questionnaire that the low temperature MCT is easier to drink. The low temperature MCT improves the image quality of MRCP and contributes to performing noninvasive examination.

The effects of hypotonic and isotonic negative contrast agent on gastrointestinal distention and physiological intake of 18F-FDG.

The objective of this study was to explore the effects of hypotonic and isotonic oral mannitol on intestinal distention and fluorine-18 fluorodeoxyglucose ((18)F-FDG) intake in PET/computed tomography (CT) imaging. A total of 124 patients without gastrointestinal disease were evaluated with PET/CT imaging and divided into four groups using a random number table. Group 1 drank plain water, group 2 drank 2.5% mannitol, group 3 drank 2.5% mannitol and also received 10 mg of scopolamine butylbromide, and group 4 drank 2.5% mannitol and also received 20 mg of scopolamine butylbromide. The patients in each group underwent PET/CT imaging 50 min after (18)F-FDG injection. In these groups, differences such as age, sex, disease distribution, oral liquid amount, and adverse reactions were compared. Gastrointestinal distention and F-FDG intake were analyzed by two experts in nuclear medicine by visual observation. Data were statistically analyzed using a rank-sum test, R×C contingency table, one-way analysis of variance, and a paired t-test. There were no significant differences in blood glucose levels after oral administration of 2.5% mannitol (t=0.62, P>0.05). Gastrointestinal distention of patients in groups 2, 3, and 4 was superior to that of patients in group 1 (P<0.05/6). In addition to the sigmoid colon and rectum, (18)F-FDG intake in each part of the gastrointestinal tract in groups 2, 3, and 4 was less than that in group 1 (P<0.05/6). Patients in group 4 experienced significantly more adverse reactions compared with patients in the other groups (P<0.05). Oral negative contrast agent and hypotonic bowel preparation decreased the physiological intake of (18)F-FDG, increased the distention of the gastrointestinal tract, and thus improved the image quality.

Utilization of Milk as an Oral Contrast Agent in CT Scan of the Abdomen

The present study aimed to evaluate using the whole milk as alternative oral contrast for the as-sessment of gastrointestinal CT enterography. Fifty patients undergo (18 female and 32 male) aged from 21 to 79 years (mean 45 years) undergo abdominal CT at the department of diagnostic radiology of King Abdulaziz University Hospital. They receive 1 - 1.5 liter whole milk. Siemens SOMATOM definition CT Scan Machine with 64 slices and dual source was utilized to image all pa-tients in research population group where iodinated oral contrast media was replaced by a whole milk available in the local market. Patients were scanned as per the routine protocol used for CT Abdomen at KAUH-CT Unit: Helical Mode with 0.7 Pitch was performed on all paints in supine po-sition using a 16-detector row scanner (Bright Speed S, General Electric-Milwaukee Wisconsin, USA). The following parameters were applied: collimation of 16 × 0.625 (1.25 - 3.75) mm, pitch of 3, Slice thickness: 5 mm, gantry rotation time of 400 mAs, tube voltage of 120 KV and scan time 11.05 second. The images of all cases were reviewed by two qualified radiologists. Conclusion: The present study suggested that whole milk was found to be an effective alternative negative contrast for the assessment of the jejunum, ileum and terminal ileum in CT enterography. It was excellent for gastric imaging and we recommended replacing milk as negative oral contrast since it is available and cost effective. Further research to be conducted with modified milk drinking timing for better large bowel distention.

Comparative Study of Pineapple Juice as a Negative Oral Contrast Agent in Magnetic Resonance Cholangiopancreatography

The aim of this study was to compare the image quality of magnetic resonance Cholangiopancreatography (MRCP) using Pineapple Juice (PJ) or ranitidine as negative oral contrast agents and no agent. MRCP images of patients administered PJ (n = 117) or Ranitidine (n = 110) at random, and patients without an agent (n = 50) were evaluated. The subjective image quality of the overall, extra hepatic bile duct and pancreatic duct and the degree of elimination of gastrointestinal fluid were scored by two blinded radiologists. RESULTS were compared using Mann-Whitney's U-test. The degrees of elimination of gastro duodenal fluid of PJ and ranitidine were significantly better than those without an agent (p < 0.01 and p < 0.01, respectively). The subjective image quality of PJ of the overall and extra hepatic bile duct were significantly better, although no significant differences for ranitidine were observed compared with those without an agent (p < 0.01 and p =0.23, p = 0.025 and p = 0.18). There were no significant differences for the pancreatic duct (p = 0.13 and p = 0.20), nor were there any significant differences in the evaluations between PJ and ranitidine (p = 0.21 and p = 0.96). PJ showed better performance compared to that of conventional ranitidine in terms of pancreatic and biliary depiction and safety.

Evaluation of date syrup as an oral negative contrast agent for MRCP.

The purpose of this study was to compare the in vitro effects of date syrup with those of other contrast agents by qualitative and quantitative analysis and in vivo evaluation of the use of date syrup to improve the quality of MRCP images. Phantoms containing date syrup, ferumoxsil, pineapple juice, and water were imaged by 1.5-T MRI with T2-weighted and MRCP sequences, and signal-to-noise ratios were calculated. Biochemical analysis of date syrup was performed to find the nature of iron in it, and the iron content was quantified by energy-dispersive x-ray spectroscopy. Sixty patients underwent MRCP before and 30 minutes after ingestion of 100 mL of date syrup. Unenhanced and contrast-enhanced images were scored for gastrointestinal tract signal suppression and visualization of various pancreaticobiliary structures. In vitro evaluation showed that images obtained with date syrup had a signal-to-noise ratio comparable to that of images obtained with ferumoxsil in T2-weighted and MRCP sequences. The iron concentration in date syrup was 2.6 mg/dL, and it was in ferric form. Images obtained after oral contrast administration had statistically significant improvement in gastrointestinal tract signal suppression (p < 0.001) and an increase in visibility of the common bile duct, cystic duct, and pancreatic duct (all p < 0.001). No adverse effects were noted in any of the patients. Date syrup can be used as a negative oral contrast agent for gastrointestinal tract signal suppression during MRCP and for improving visualization of various pancreaticobiliary structures.

The effective use of acai juice, blueberry juice and pineapple juice as negative contrast agents for magnetic resonance cholangiopancreatography in children

Magnetic resonance cholangiopancreatography (MRCP) is commonly performed in the evaluation of known or suspected pancreaticobiliary disease in children. The administration of a negative oral contrast agent can improve the quality of the examination without significant additional cost. We describe our experience with certain brands of acai juice, blueberry juice and pineapple juice as negative oral contrast agents in children. We believe these fruit juices are safe, palatable and may improve MRCP image quality.

Use of positive oral contrast agents in abdominopelvic computed tomography for blunt abdominal injury: meta-analysis and systematic review

To determine whether positive oral contrast agents improve accuracy of abdominopelvic CT compared with no, neutral or negative oral contrast agent. Literature was searched for studies evaluating the diagnostic performance of abdominopelvic CT with positive oral contrast agents against imaging with no, neutral or negative oral contrast agent. Meta-analysis reviewed studies correlating CT findings of blunt abdominal injury with positive and without oral contrast agents against surgical, autopsy or clinical outcome allowing derivation of pooled sensitivity and specificity. Systematic review was performed on studies with common design and reference standard. Thirty-two studies were divided into two groups. Group 1 comprised 15 studies comparing CT with positive and without oral contrast agents. Meta-analysis of five studies from group 1 provided no difference in sensitivity or specificity between CT with positive or without oral contrast agents. Group 2 comprised 17 studies comparing CT with positive and neutral or negative oral contrast agents. Systematic review of 12 studies from group 2 indicated that neutral or negative oral contrasts were as effective as positive oral contrast agents for bowel visualisation. There is no difference in accuracy between CT performed with positive oral contrast agents or with no, neutral or negative oral contrast agent. • There is no difference in the accuracy of CT with or without oral contrast agent. • There is no difference in the accuracy of CT with Gastrografin or water. • Omission of oral contrast, utilising neutral or negative oral contrast agent saves time, costs and decreases risk of aspiration.