Small bowel hydro‐MR imaging for optimized ileocecal distension in Crohn's disease: Should an additional rectal enema filling be performed?

PURPOSE: To assess the impact of an additional rectal enema filling in small bowel hydro-MRI in patients with Crohn's disease. MATERIALS AND METHODS: A total of 40 patients with known Crohn's disease were analyzed retrospectively: 20 patients only ingested an oral contrast agent (group A), the other 20 subjects obtained an additional rectal water enema (group B). For small bowel distension, a solution containing 0.2% locust bean gum (LBG) and 2.5% mannitol was used. In all patients, a breathhold contrast-enhanced T1w three-dimensional volumetric interpolated breathhold examination (VIBE) sequence was acquired. Comparative analysis was based on image quality and bowel distension as well as signal-to-noise ratio (SNR) measurements. MR findings were compared with those of conventional colonoscopy, as available (N = 25). RESULTS: The terminal ileum and rectum showed a significantly higher distension following the rectal administration of water. Furthermore, fewer artifacts were seen within group B. This resulted in a higher reader confidence for the diagnosis of bowel disease, not only in the colon, but also in the ileocecal region. Diagnostic accuracy in diagnosing inflammation of the terminal ileum was 100% in group B; in the nonenema group there were three false-negative diagnoses of terminal ileitis. CONCLUSION: Our data show that the additional administration of a rectal enema is useful in small bowel MRI for the visualization of the terminal ileum. The additional time needed for the enema administration was minimal, and small and large bowel pathologies could be diagnosed with high accuracy. Thus, we suggest that a rectal enema in small bowel MR imaging be considered.     

Dose optimization of mannitol solution for small bowel distension in MRI

PURPOSE: To optimize the dose of a hydro solution containing 2.5% mannitol and 0.2% locust bean gum (LBG) for small bowel MRI in terms of bowel distension and patient acceptance. MATERIALS AND METHODS: A total of 10 healthy volunteers ingested a hydro solution containing 2.5% mannitol and 0.2% LBG. Four different volumes (1500, 1200, 1000, and 800 ml) were assessed on four different examination days. Small bowel distension was quantified on coronal two-dimensional TrueFISP images by measuring the diameter of eight bowel loops throughout the jejunum and the ileum. In addition, volunteer acceptance was evaluated for every single examination by using a questionnaire. RESULTS: Optimal distension was obtained with either, 1000, 1200, or 1500 ml, with no statistically significant differences in distension between these groups. Administration of 800 ml led to significantly less distension of the small bowel. Significantly less side effects were noted using either 800 or 1000 ml compared to using larger volumes. CONCLUSION: We recommend a dose of 1000 ml mannitol/LBG solution as an oral contrast agent for optimal bowel distension and minimal side effects.     

Cine magnetic resonance imaging of the small bowel: comparison of different oral contrast media

PURPOSE: To evaluate several substances regarding small bowel distension and contrast on balanced steady-state free precession (bSSFP) cine magnetic resonance (MR) images. MATERIAL AND METHODS: Luminal contrast was evaluated in 24 volunteers after oral application of two different contrast agent groups leading to either bright lumen (pineapple, blueberry juice) or dark lumen (tap water, orange juice) on T1-weighted images. Bowel distension was evaluated in 30 patients ingesting either methylcellulose or mannitol solution for limiting intestinal absorption. Fifteen patients with duodeno-jejunal intubation served as the control. Quantitative evaluation included measurement of luminal signal intensities and diameters of four bowel segments, qualitative evaluation assessed luminal contrast and distension on a five-point scale. RESULTS: Quantitative and qualitative evaluation of the four contrast agents revealed no significant differences regarding luminal contrast on bSSFP images. Quantitative evaluation revealed significantly lower (P<0.05) small bowel distension for three out of four segments (qualitative evaluation: two out of four segments) for methylcellulose in comparison to the control. Mannitol was found to be equal to the control. CONCLUSION: Oral ingestion of tap water or orange juice in combination with mannitol is recommended for cine MR imaging of the small bowel regarding luminal contrast and small bowel distension on bSSFP sequences.     

Combined small and large bowel MR imaging in patients with Crohn’s disease: a feasibility study

MRI of the small bowel is a new method for the assessment of inflammatory bowel diseases. However, inflammatory bowel disease can affect both the small and large bowel. Therefore, our goal was to assess the feasibility of displaying the small bowel and colon simultaneously by MR imaging. Eighteen patients with inflammatory bowel disease were studied. For small bowel distension, patients ingested a solution containing mannitol and locust bean gum. Furthermore, the colon was rectally filled with water. MR examinations were performed on a 1.5-T system. Before and after intravenous gadolinium administration, a T1w data set was collected. All patients underwent conventional colonoscopy as a standard of reference. The oral ingestion and the rectal application of water allowed an assessment of the small bowel and colon in all patients. By means of MRI (endoscopy), 19 (13) inflamed bowel segments in the colon and terminal ileum were detected. Furthermore, eight additional inflammatory lesions in the jejunum and proximal ileum that had not been endoscopically accessible were found by MRI. The simultaneous display of the small and large bowel by MRI is feasible. Major advantages of the proposed MR concept are related to its non-invasive character as well as to the potential to visualize parts of the small bowel that cannot be reached by endoscopy.     

MRI in Crohn's disease after transduodenal contrast administration using negative oral MRI contrast media

PURPOSE: To compare the efficacy and quality of conventional and MR enteroclysis with different filling methods regarding the assessment of extension and extraluminal manifestations in Crohn's disease. MATERIAL AND METHODS: 190 patients with known Crohn's disease were studied following small bowel enteroclysis, after oral administration or direct transduodenal filling in the MRI-department.T1- and T2-weighted breathhold MRI-scans w/o spectral fat suppression w/o i.v. Gd-DTPA were applied using negative oral superparamagnetic contrast media. RESULTS: Typical findings were marked bowel wall thickening with laminated wall contrast enhancement. In 135 patients 98,2% of affected bowel segments, 97,5% of stenoses and all 16 fistulas were detected, when conventional enteroclysis was employed as standard of reference. Additional important extraluminal findings such as ileoileal (n = 18), ileosigmoidal adhesions (n = 12), extraluminal abscesses (n = 35) and pseudotumors (n = 8) were visualized in 73/135 patients. Concerning the distension of jejunum and ileum, oral filling was rated significantly inferior to transduodenal filling in all small bowel segments,whereas filling in the MRI-unit was rated superior to fluoroscopic, mostly due to a mean transport time of 20 min to the MRI-unit. CONCLUSION: No clinically important findings of enteroclysis were missed when using MRI. Therefore, in patients with Crohn's disease, conventional enteroclysis can be replaced by MRI. For optimal bowel distension oral contrast administration is inferior to transduodenal filling, if a larger time delay between filling and the MRI-scan can be avoided.     

Oral contrast agents for small bowel distension in MRI: influence of the osmolarity for small bowel distention

To assess the effect of the osmolarity for small bowel distension in MRI, ten volunteers ingested at two separate occasions negative oral contrast agents with different quantity and osmolarity: (1) a water solution combined with 2.0% sorbitol and 0.2% locus bean gum (LBG) with a quantity of 1500 ml and an osmolarity of 148 mOsmol/l, (2) a water solution combined with 2.0% sorbitol and 2.0% barium sulphate with a quantity of 1000 ml and an osmolarity of 194 mOsmol/l. Small bowel distension was quantified on coronal 2D-TrueFISP images by measuring the small bowel diameters. There were no statistically significant differences in mean small bowel diameter between both contrast agents. The mean small bowel distension was 19.2 mm after ingestion of 1500 ml of sorbitol-LBG solution and 19.0 mm after ingestion of 1000-ml sorbitol–barium sulphate solution. Furthermore, all volunteers found the ingestion of 1000-ml solution more pleasant than the 1500-ml solution. The ingestion of 1000 ml of sorbitol–barium sulphate solution led to a sufficient small bowel distension compared to 1500 ml of sorbitol–LBG solution. The side effect rate of both solutions was low. Based on these data, we recommend a quantity of 1000 ml of sorbitol–barium sulphate solution as an alternative for 1500-ml sorbitol–LBG solution for optimal bowel distension.     

两种肠道准备方法在多层螺旋CT小肠造影中的效果对比

目的在小肠造影CT检查中,探讨2种口服对比剂对小肠充盈扩张效果和CT采集时间的影响。方法本文分析了以2.5%等渗甘露醇溶液为对比剂49例和以非离子型碘剂稀释液为对比剂57例,用药量为1 500～2 000 mL,分别在30 min、45 min和60 min 3个时间点,应用螺旋CT并综合三维重建技术采集小肠造影数据,根据对比剂到达回盲部来评价小肠充盈效果。结果口服等渗甘露醇溶液的49例观测结果为：肠管充盈扩张较好,CT值改变不大,对比剂前端到达回盲部时间相对提前;口服非离子型碘剂稀释液的57例观测结果为：肠管对比清晰,CT值改变较大。结论小肠完全充盈的时间和效果,与应用对比剂类型有关,同时对比剂的量及服用的持续程度对小肠的充盈扩张非常重要。     

MRI of the small bowel: can sufficient bowel distension be achieved with small volumes of oral contrast?

Sufficient luminal distension is mandatory for small bowel imaging. However, patients often are unable to ingest volumes of currently applied oral contrast compounds. The aim of this study was to evaluate if administration of low doses of an oral contrast agent with high-osmolarity leads to sufficient and diagnostic bowel distension. Six healthy volunteers ingested at different occasions 150, 300 and 450 ml of a commercially available oral contrast agent (Banana Smoothie Readi-Cat, E-Z-EM; 194 mOsmol/l). Two-dimensional TrueFISP data sets were acquired in 5-min intervals up to 45 min after contrast ingestion. Small bowel distension was quantified using a visual five-grade ranking (5 = very good distension, 1 = collapsed bowel). Results were statistically compared using a Wilcoxon-Rank test. Ingestion of 450 ml and 300 ml resulted in a significantly better distension than 150 ml. The all-over average distension value for 450 ml amounted to 3.4 (300 ml: 3.0, 150 ml: 2.3) and diagnostic bowel distension could be found throughout the small intestine. Even 45 min after ingestion of 450 ml the jejunum and ileum could be reliably analyzed. Small bowel imaging with low doses of contrast leads to diagnostic distension values in healthy subjects when a high-osmolarity substance is applied. These findings may help to further refine small bowel MRI techniques, but need to be confirmed in patients with small bowel disorders.     

Feasibility of using automated insufflated carbon dioxide (CO2) for luminal distension in 3.0T MR colonography

Purpose

Primary aim of our study was to prospectively evaluate the feasibility of automated carbon dioxide (CO₂) delivery as luminal distending agent in 3.0 T MR colonography.

Materials and methods

Rectally insufflated CO₂ was evaluated in four groups with different bowel preparation (A–D). Bowel preparation regimes were: gadolinium-based tagging (A), bowel purgation (B), barium-based tagging (C) and iodine-based tagging (D). Supine (3D)T1w-FFE and (2D)T2w-SSFSE series were acquired. Each colon was divided into six segments (cecum S1–rectum S6). Two observers independently assessed the presence of artefacts, diagnostic confidence and segmental colonic distension. Also characteristics of the residual stool (presence, composition and signal-intensity) were assessed per segment. Discomfort was assessed with questionnaires.

Results

Fourteen healthy subjects were included. Colonic distension by means of rectally insufflated CO₂ was not associated with susceptibility artefacts. Overall image quality was affected by the presence of bowel motion-related artefacts: none of the segments in 3DT1w-series and 10/84 (12%) colon segments in 2DT2w-series were rated artefact-free by both observers. Diagnostic confidence ratings were superior for the 2DT2w-SSFSE series. Overall bowel distension was rated adequate to optimal in 312/336 (93%) colon segments.

Conclusion

MR colonography at 3.0 T using carbon dioxide (CO₂) for colonic distension is technically feasible. The presence of intraluminal CO₂ did not result in susceptibility artefacts, although overall image quality was influenced by artefacts.     

Comparison of neutral oral contrast versus positive oral contrast medium in abdominal multidetector CT

To determine whether neutral contrast agents with water-equivalent intraluminal attenuation can improve delineation of the bowel wall and increase overall image quality for a non-selected patient population, a neutral oral contrast agent (3% mannitol) was administered to 100 patients referred for abdominal multidetector row computed tomography (MDCT). Their results were compared with those of 100 patients given a positive oral contrast agent. Qualitative and quantitative measurements were done on different levels of the gastrointestinal tract by three experienced readers. Patients given the neutral oral contrast agent showed significant better qualitative results for bowel distension (P < 0.001), homogeneity of the luminal content (P < 0.001), delineation of the bowel-wall to the lumen (P < 0.001) and to the mesentery (P < 0.001) and artifacts (P < 0.001), leading to a significant better overall image quality (P < 0.001) than patients receiving positive oral contrast medium. The quantitative measurements revealed significant better distension (P < 0.001) and wall to lumen delineation (P < 0.001) for the patients receiving neutral oral contrast medium. The present results show that the neutral oral contrast agent (mannitol) produced better distension, better homogeneity and better delineation of the bowel wall leading to a higher overall image quality than the positive oral contrast medium in a non-selected patient population.     

Feasibility of small bowel flow rate measurement with MRI

Objective:

To evaluate whether it is feasible to measure the segmental flux of small bowel content using MR phase‐contrast (PC) pulse sequences.

Materials and methods:

Using a phantom the accuracy of flux measurements was validated. Afterwards, 10 volunteers were included in a prospective clinical trial. To provide standardized small bowel distension, all volunteers ingested four equal portions of 400 mL of water doped with 5 mL gadoterate and 5.8 g Metamucil mite. The MR protocol covering the sagittal cross‐sections of the small bowel included several two‐dimensional (2D) PC sequences with a velocity encoding of 7 cm/second at a temporal resolution of 0.55 second. As proof of concept time‐dependent flux was measured after intravenous (i.v.) administration of a spasmolytic agent in one volunteer.

Results:

Phantom measurements resulted in an excellent correlation between pump and PC measured flow rates (R = 0.999). Time‐resolved small bowel flux was successfully measured in distended small bowel loops of all volunteers. A mean flow rate of 0.188 mL/second (standard deviation ± 0.144 mL/second) was documented. The flux plots presented a sinus wave‐like shape with regular aboral and oral flow. A spasmolytic effect both on flux and motility could be shown with residual flux despite complete arrest of small bowel motility.

Conclusion:

PC MRI allows time‐resolved in vivo measurement of small bowel flux in single well‐distended bowel loops filled with gadolinium‐doped aqueous solution. J. Magn. Reson. Imaging 2010;32:345–351. © 2010 Wiley‐Liss, Inc.     

Evaluation of the effects of oral water and low-density barium sulphate suspension on bowel appearance on FDG-PET/CT

The purpose of this study is to assess which of five bowel preparation regimes offers superior bowel distension and to assess if these regimes adversely affect FDG activity on PET/CT imaging. The study conformed to HIPAA regulations. Ninety patients were divided into five groups of 18 who received no oral contrast agent (group A); 900 ml of water orally (group B); or 900, 1,350, or 1,800 ml of LDB (groups C, D, E, respectively). PET/CT examinations were assessed quantitatively (bowel diameter, SUV) and qualitatively (visual assessment grading scale) for bowel distension and FDG activity by two blinded readers. ANOVA was utilized to determine if a statistically significant difference (SSD) existed between the groups in terms of distension and FDG uptake. Qualitatively superior bowel distension was observed in group C (LDB) compared to B (water) and greater distension was noted with increased volumes of LDB in C, D, and E. Quantitatively there was an SSD in mean distension between groups C and B (P?<?0.001 except duodenum). Qualitatively and quantitatively there was no significant difference in bowel FDG uptake among the groups (P?>?0.05). LDB as an oral contrast agent provides superior bowel distension over water and does not induce increased FDG bowel activity.     

Osmolarity: a decisive parameter of bowel agents in intestinal magnetic resonance imaging

The aim was to evaluate the importance of the osmolarity of different oral agents for bowel distension and the level of related adverse events. The longitudinal design included the exposition of different oral MR agents on two separate occasions. Four groups of volunteers were randomly given 350 ml gastrografin of three different concentrations and water. On the second occasion they received mannitol, iohexol or iodixanol with equivalent osmolarities, but the control group (water) received mannitol. We recorded the outcomes as the degree of bowel distension determined as the mean bowel section area and the total level of discomfort recorded from a visual analogue scale (VAS). The statistical analysis included scatter plots with the best-fitted line with linear regression to study the association between osmolarity and section area and the association between osmolarity and adverse events. A dose-response association was found between increasing osmolarity levels and bowel area in square centimeters (P=0.00001). A similar dose-response association existed between increasing levels of osmolarity and adverse events (P=0.001). Osmolarity appears to be more important for bowel distension than the physico-chemical characteristics of the nonabsorbable oral agents. The optimum osmolarity level is determined by the patient’s tolerance of the adverse events.     

Head-to-head comparison of oral contrast agents for cross-sectional enterography: small bowel distention, timing, and side effects

OBJECTIVE: To determine small bowel distention, scanning time, and side effects of commercially available oral contrast agents used in cross-sectional enterography. METHODS: Ten healthy volunteers ingested 2000 mL of water, methylcellulose, polyethylene glycol (PEG), or 1350 mL of low-concentration barium (LCB) followed by 500 mL water on different days. Magnetic resonance imaging occurred every 10 minutes from 30 to 90 minutes after ingestion. Small bowel distention was compared between time points and agents. Volunteers ranked side effects, drinking difficulty, and preference. RESULTS: By quantitative assessment, PEG and LCB distended small bowel loops better than water and methylcellulose (P < 0.0001). Time to optimal distention of the terminal ileum was from 51 to 72 minutes. Water and methylcellulose had the fewest side effects. Water was the most preferred contrast and PEG the least. CONCLUSIONS: Polyethylene glycol and LCB distend small bowel better than water and methylcellulose. Polyethylene glycol was the most difficult to drink and least preferred agent.     

Optimization of oral contrast agents for MR imaging of the small bowel

Effect on small-bowel distention of additives to water as contrast agents for magnetic resonance (MR) imaging was assessed. Oral contrast agents included water and water in combination with mannitol, a bulk fiber laxative, locust bean gum, and a combination of mannitol and locust bean gum. Filling of the small bowel was quantified on coronal images obtained with two-dimensional true fast imaging with steady-state precession sequence; bowel diameters were measured. Ingestion of water with locust bean gum and mannitol provided the best distention of the small bowel. MR imaging of the small bowel with oral administration of water can be improved with addition of osmotic and nonosmotic substances that lead to decreased water resorption.     

Oral contrast agents for small bowel MRI: comparison of different additives to optimize bowel distension

The purpose of this study was to compare two osmotic carbohydrate sugar alcohols (mannitol 2.5% and sorbitol 2.5%, 2.0%, and 1.5% watery solutions) in combination with 0.2% locust bean gum (LBG) for small bowel distension for MR imaging. Small bowel distension was quantified on coronal 2D TrueFISP images by measuring the diameters of 16 small bowel loops in each of 12 healthy subjects (age range 31–55 years). Additionally, the grade of small bowel distension was rated qualitatively. Patient acceptance concerning nausea, vomiting, flatulence, and diarrhea was noted for each solution, and all results were compared by a Wilcoxon test or t test, respectively. The ingestion of water combined with LBG and either 2.5% mannitol or 2.0% sorbitol showed the best distension of the small bowel. The lowest side effect rate was observed following ingestion of sorbitol in a concentration of 2.0 and 1.5%. Based on these data, we recommend a combination of LBG and 2% sorbitol use for optimal bowel distension and minimal side effects resulting in enhanced patient acceptance.     

Computed tomography of the bowel: A prospective comparison study between four techniques

Objectives

The major objective was to prospectively compare the grade of bowel distension obtained with four different computed tomography (CT) techniques dedicated for the examination of the small intestine (CT enteroclysis [CTE] and enterography [CTe]), of the colon (CT with water enema [CT-WE]), or both (CTe with water enema [CTe-WE]). The secondary objective was to assess patients’ tolerance toward each CT protocol.

Materials and methods

Recruitment was designed to obtain four groups of the same number of patients (30). Each group corresponded to a specific CT technique, for a total of 120 consecutive outpatients (65 male and 55 female, mean age 51.09 ± 13.36 years).CTE was performed after injection of methylcellulose through a nasojejunal tube, while in the CTe protocol a polyethylene glycol electrolyte solution was orally administered to patients prior to the CT acquisition. In the CT-WE protocol intraluminal contrast (water) was administered only by a rectal enema, while CTe-WE technique included both a rectal water enema and oral ingestion of neutral contrast material to obtain a simultaneous distension of small and large bowel.CT studies were reviewed in consensus by two gastrointestinal radiologists who performed a quantitative and qualitative analysis of bowel distension on a per segment basis. The presence and type of adverse effects were recorded.

Results

CTE provided the best distension of jejunal loops (median diameter 27 mm, range 17–32 mm) when compared to all the other techniques (p < 0.0001). The frequency of patients with an adequate distension of the terminal ileum was not significantly different among the four groups (p = 0.0608). At both quantitative and qualitative analysis CT-WE and CTe-WE determined a greater and more consistent luminal filling of the large intestine than that provided by both CTE and CTe (p < 0.0001 for all colonic segments). Adverse effects were more frequent in patients belonging to the CTE group (p < 0.0028).

Conclusions

CTE allows an optimal distension of jejunal loops, but it is the most uncomfortable CT protocol. When performing CT-WE, an adequate retrograde distension of the terminal ileum was provided in a particularly high percentage of patients. CTe-WE provides a simultaneous optimal distension of both small and large bowel.     

Improvement of distension and mural visualization of bowel loops using neutral oral contrasts in abdominal computed tomography

AIM: To assess and compare the image quality of 4% sorbitol and diluted iodine 2% (positive oral contrast agent) in abdomino-pelvic multi-detector computed tomography.METHODS: Two-hundred patients, referred to the Radiology Department of a central educational hospital for multi-detector row abdominal-pelvic computed tomography, were randomly divided into two groups: the first group received 1500 mL of 4% sorbitol solution as a neutral contrast agent, while in the second group 1500 mL of meglumin solution as a positive contrast agent was administered in a one-way randomized prospective study. The results were independently reviewed by two radiologists. Luminal distension and mural thickness and mucosal enhancement were compared between the two groups. Statistical analysis of the results was performed by Statistical Package for the Social Sciences software version 16 and the Mann-Whitney test at a confidence level of 95%.RESULTS: Use of neutral oral contrast agent significantly improved visualization of the small bowel wall thickness and mural appearance in comparison with administration of positive contrast agent (P < 0.01). In patients who received sorbitol, the small bowel showed better distention compared with those who received iodine solution as a positive contrast agent (P < 0.05).CONCLUSION: The results of the study demonstrated that oral administration of sorbitol solution allows better luminal distention and visualization of mural features than iodine solution as a positive contrast agent.     

能谱CT等渗甘露醇胃肠低张造影诊断消化道疾病的价值

目的评价口服等渗甘露醇胃肠低张造影结合能谱成像在消化道疾病诊断中的临床价值。方法回顾性分析56例经手术与病理证实消化道病变患者的资料,所有患者均行口服复方聚乙二醇电解质散清洁肠道,检查当日口服2．5％甘露醇等渗溶液行肠道充盈并低张。采用双能CT宝石能谱成像技术行平扫及双期增强扫描,将原始数据应用能谱分析软件,获得组织最佳对比噪声比（CNR）的单能图像,结合水一碘分离图及能谱曲线分析,并在ADW4．5工作站上进行MPR、MIP和VRT。结果56例患者均能顺利完成检查,胃肠道适度扩张、充盈密度均匀,气粪影干扰少,胃壁及肠壁与低密度的胃腔和肠腔形成鲜明的对比。清楚显示胃肿瘤15例,小肠肿瘤9例,小肠Crohn病2例,小肠过敏性紫癜1例,小肠血管畸形2例,结肠肿瘤13例,结肠息肉8例,直肠肿瘤6例,直肠息肉2例,降结肠及乙状结肠缺血3例。结论口服等渗甘露醇胃肠低张造影可以提供良好的胃肠道显示背景,是一种安全、方便、高效的胃肠检查方法,同时结合能谱成像,可突显小病灶,优化血管成像,判断病灶同源性等方面具有一定的价值,且可真正达到胃肠道一站式检查。     

The effect of oral contrast on large bowel activity in FDG-PET/CT

PURPOSE: The purpose of this study was to determine the effect of oral contrast on FDG uptake in the colon and to determine the normal distribution of FDG in the colon. METHODS: Sixty patients (30 patients in no contrast group and 30 patients in the received contrast group) underwent FDG-PET/ CT scans. The pattern of FDG uptake was classified into 5 patterns (diffuse, segmental, single-nodular, multi-nodular, and other) in 5 segments (ascending, transverse, descending, and rectosigmoid colon). SUVs of the no oral contrast group were examined. The ratios of FDG uptake patterns were compared in the received contrast group and no contrast group to evaluate the effect of oral contast. The effect of attenuation correction on the uptake pattern was evaluated by comparison of the attenuation-corrected and non-attenuation-corrected PET images. RESULTS: In the no contrast group, there was no significant uptake in 72 segments (59%) and a diffuse pattern was seen in 29 segments (24%), most frequently in the ascending colon and descending colon. A segmental pattern was seen in 15 segments (13%), most frequently in the rectosigmoid colon. A single-nodular pattern was seen in 3 segments (3%) and multi-nodular pattern in 1 segment (1%). A nodular pattern was seen only in the ascending colon. SUVmax of the ascending colon and that of the rectosigmoid colon were significantly higher than those of the transverse and descending colon. The frequencies of diffuse, multi-nodular and 'other' patterns were significantly higher in the received contrast group than in no contrast group. There was no significant difference between the frequency of the segmental pattern or the single nodular pattern in the two groups. There was no significant difference between the uptake patterns with attenuation correction and those without attenuation correction in either the received contrast group or no contrast group. CONCLUSION: Normal FDG uptake in the large bowel may show various degrees and patterns of uptake among the colonic segments. Oral contrast agent can cause focal or diffuse increased FDG uptake, which may be induced not only by the high CT density of oral contrast but also by an accelerated physiologic reaction of the large bowel.