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Multidetector computed tomography (MDCT) manifestations of the normal duodenal papilla
European Journal of Radiology 82 (2013) 918–922
Contents lists available at SciVerse ScienceDirect
European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad
Multidetector computed tomography (MDCT) manifestations of the normal duodenal papilla Can-Hui Sun a,1 , Xuehua Li a,1 , Tao Chan b,1 , Zhenpeng Peng a,1 , Zhi Dong a,1 , Yanji Luo a,1 , Zi-Ping Li a,1 , Shi-Ting Feng a,∗,1 a b
Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China Medical Imaging Department, Union Hospital, Hong Kong
a r t i c l e
i n f o
Article history: Received 25 September 2012 Received in revised form 9 December 2012 Accepted 2 January 2013 Keywords: Duodenal papilla Tomography X-ray computed tomography
a b s t r a c t Objective: This study aimed to investigate Multidetector Computed Tomography (MDCT) manifestations of the normal duodenal papilla, thereby improving the knowledge on the CT manifestations of the normal anatomy of the duodenal papilla. Methods: A retrospective study was conducted by reviewing the CT results of 70 normal duodenal papilla cases examined by 64-MDCT. The analysis particularly focused on the position, size, morphology, and enhancement pattern of the duodenal papilla, as well as the ampulla of Vater. Results: In axial images, the average base diameter of the duodenal papilla was (7.3 ± 1.4) mm, whereas the average height was (6.5 ± 1.8) mm. Majority of the duodenal papilla (52.9%, 37/70) showed a round shape. In most cases (97.1%, 68/70), the duodenal papilla were located at the middle and lower third of the descending duodenum. In 84.3% of the cases (59/70), the arterial phase enhanced CT scan images were optimal for the visualization of the papilla. The “target sign” could be clearly identified from arterial phase images in 71.4% (50/70) of the cases. In 72.9% (51/70) of the cases, the ampulla of Vater had a common channel (Y type). Conclusion: 64-MDCT can clearly visualize the normal anatomy of the duodenal papilla and surrounding structures, thereby providing valuable information for the diagnosis and treatment of diseases in this region. © 2013 Elsevier Ireland Ltd. All rights reserved.
1. Introduction The duodenal papilla is the papillary structure formed by the elevation of the duodenal mucosal plicae toward the lumen [1–3]. Being the connecting point between the liver, gallbladder, pancreas and intestines, pathological changes in the duodenal papilla can induce a series of diseases involving these major organs; sometimes, even systemic diseases may occur [2,4]. Moreover, different types of lesions could lead to different characteristic morphological changes of the duodenal papilla. CT examination,
∗ Corresponding author at: Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, 58th, The Second Zhongshan Road, Guangzhou, Guangdong, China. Tel.: +86 20 87755766x8471; fax: +86 20 87615805. E-mail addresses: [email protected] (C.-H. Sun), [email protected] (X. Li), [email protected] (T. Chan), [email protected] (Z. Peng), [email protected] (Z. Dong), [email protected] (Y. Luo), [email protected] (Z.-P. Li), [email protected], [email protected] (S.-T. Feng). 1 All authors actively participated in this study. Drs Can-Hui Sun and Xuehua Li wrote the manuscript. Shi-Ting Feng conceived the conception and design of the study, Zhenpeng Peng performed acquisition of data, Zhi Dong and Yanji Luo performed interpretation of data, Zi-Ping Li performed statistical analysis, Tao Chan revised and reviewed the article for important intellectual content. All authors had full access to the data obtained, and all approved the final manuscript. 0720-048X/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ejrad.2013.01.007
especially multiple-slice spiral CT, can accurately reveal the structural changes in the duodenal papilla, as well as the relationship between these lesions and the surrounding tissues, thereby playing an increasingly important role in diagnosis [2]. Due to significant variability of the duodenal papilla anatomy, accurate knowledge about normal appearances of the duodenal papilla is crucial for diagnosis of pathological events in this region. Many researchers have studied the anatomy of duodenal papilla using approaches including dissection examination and endoscopy. However, there have only been a few reports regarding the imaging manifestations of the duodenal papilla [4–8], and no systematic evaluation of the normal anatomy on MDCT has been reported before. In the present study, we analyzed 70 normal duodenal papilla using 64-MDCT, to improve the knowledge on the CT manifestations of the normal anatomy of the duodenal papilla 2. Material and methods 2.1. Patients All adult patient who had undergone both dual phase contrast enhanced MDCT of upper abdomen and endoscopy within a 3 day interval during the period from September 2009 and October 2010
C.-H. Sun et al. / European Journal of Radiology 82 (2013) 918–922
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were retrospectively retrieved from our PACS. From these, subjects of the current study were selected based on the following criteria: (1) no pathological lesions or congenital abnormalities in the liver, gallbladder, pancreas, duodenum or the surrounding regions, such as peri-ampullary duodenal diverticula; (2) no duodenal filling defects (isotonic mannitol solution was used to distend the duodenum) and clear visibility of the duodenal papilla against the fluid and gas around the region; (3) no abnormality of duodenal papilla as revealed on endoscopy. Altogether 70 cases were analyzed in the current study, consisting of 36 males and 34 females, age ranged from 20 to 80 years, with the mean age of 41.5 years. The subjects were divided into 3 age groups, including 42 cases in the young adult group (≤39 years), 18 cases in the middle-aged group (40–59 years) and 10 cases in the elderly group (≥60 years). This study was HIPAA compliant and informed consent was waived by the IRB. 2.2. CT protocols Plain and dual-phase enhanced 64-MDCT was performed through the epigastric region using a Toshiba Aquilion 64-slice CT scanner (Tokyo, Japan). The parameters used were as follows: tube voltage – 120 kV, tube current – 200 mA, matrix – 512 × 512, slice thickness – 64 × 0.5 mm, spiral pitch-0.828, scanning range: from the top of the diaphragm to below inferior edge of the horizontal segment of the duodenum. Contrast agent (Ultravist 300, Bayer Healthcare Pharmaceuticals, Berlin, German) was used as the intravenous contrast agent, at the dose 1.5 ml/kg body weight, and the injection rate of 3.5 ml/s. The arterial phase CT scan was started at 32 s post-injection, whilst the venous phase scan was initiated at 65 s post-injection. The patients underwent a routine fasting for 8 h and were orally administered with 900 ml of the isotonic mannitol solution (2.5%) at 30 min prior to the scan. Right before the scan, they were orally administered with 300 ml of the isotonic mannitol solution (2.5%) to dilate the stomach and the duodenum. In order to fully dilate the descending duodenum, the patients were instructed to lie down on the right side 1–2 min before the scan and to lie on the back during the scan. For the purpose of analyzing the morphology and size of the duodenal papilla at its natural state, we did not use hypotonic agents in this study. 2.3. Observation method and items The obtained CT volume data were reformatted with slice distance of 1 mm and slice thickness of 0.5 mm, and were transmitted to the HP workstation XW8200 (Vitrea 2, version3.7) for further analysis. Images were examined by two experienced abdominal radiologists independently. The assessment that they both agreed on was considered the final result. The junction of the bile and pancreatic ducts (ampulla of Vater) was identified from the CT using the method of curved multiplanar reformation (cMPR). By tracing the ampulla of Vater to the papillary structure formed by the elevation of the duodenal mucosal plicae toward the lumen, the duodenal papilla is located (Fig. 1). The slice on which the papilla appears largest was selected for further comprehensive analysis. Based on the manifestations on the axial images, there were 4 morphological types of the duodenal papilla, i.e., round, hemispheric, conical and flat (Fig. 2). The phase of contrast enhanced CT in which the duodenal papilla was best visualized was chosen for size measurements. When both the arterial phase and the venous phase qualified for the optimal visualization, arterial phase images were used, due to the fact that majority of the other cases showed better visualization on the arterial phase. The measurements were obtained as follows. The base diameter was determined as the maximal papilla
Fig. 1. cMPR of the ampulla of Vater. In the enhanced arterial phase CT scan images, the ends of the main bile duct (the thick short arrow) and the main pancreatic duct (the thick long arrow) form the Y type ampulla of Vater, obliquely entering the descending duodenum by penetrating the medial wall to the papilla (the thin arrow).
diameter, obtained by measuring the tangent parallel with the duodenal medial wall, in the maximal slice of the axial thin-slice images (1.0 mm). The height was determined as the maximal papilla diameter obtained by measuring the tangent perpendicular to the medial wall (Fig. 3). Also, the duodenal lumen diameter was measured from the same slice. According to the appearances on coronal images, positions of the duodenal papilla were divided into 4 types: upper third of the descending duodenum, the middle third of the descending duodenum, the lower third of the descending duodenum and the horizontal duodenum. In the enhanced arterial phase images, density of the duodenal papilla was measured and compared against that of the duodenal mucosal plicae in the same slice. We defined the density of the duodenal papilla as isodensity, lowdensity, or high-density when it was equal to, lower or higher than that of adjacent mucosal plicae. The “target sign” was defined as the appearance produced the relatively lower density in the center and higher density at the border of the duodenal papilla on enhanced images. According to the relationship between pancreatic duct and common bile duct, the configuration of ampulla of Vater was classified into tree major types: Y type, V type and U type. 2.4. Statistical analysis The software package SPSS 13.0 was used for statistical analyses of the data. Comparison among size in different age groups of diameter was conducted using one-way analysis of variance. Comparison of size between two groups was conducted using the two independent sample t-test. Distribution of different types of configuration of ampulla of Vater was compared using the chi-square test. The difference was considered statistically significant when P < 0.05. 3. Results The maximal luminal diameter at the level of the duodenal papilla was (22.9 ± 1.5) mm. Of the 70 cases, the average base diameter of the duodenal papilla was (7.3 ± 1.4) mm, whereas the average height was (6.5 ± 1.8) mm. The upper limit values at 95% CI of these two parameters were 9.6 mm and 9.5 mm respectively. No statistically significant difference was found in these
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Fig. 2. Morphological type of the duodenal papilla (model). (1) Round-like; (2) Hemispheric; (3) Conical; (4) Flat.
measurements between the males and females (base diameter: t = 1.136, P = 0.260; height: t = −0.112, P = 0.911). Moreover, no statistically significant difference was observed amongst the young, middle-aged and senior groups, regarding the base diameter or height of the duodenal papilla (F = 1.318, P = 0.275 and F = 1.942, P = 0.151, respectively; Table 1). The morphology of the duodenal papilla could be categorized as 4 types: round, hemispheric, conical and flat (Fig. 4). Among the 70 cases, the percentage of each morphological type was as follows: 52.9%-round, 25.7%-hemispheric, 14.3%-conical and 7.1%-flat. The size of each type of papilla is listed in Table 1. The distribution of these 4 morphological types between male and female was not statistically different (2 = 2.842, P = 0.417). Among the 70 cases, the duodenal papilla was located in the upper third of the descending duodenum in 1 case (1.4%), in the middle third of the descending duodenum in 56 cases (80.0%), in the lower third of the descending duodenum in 12 cases (17.1%) and in the horizontal duodenum in 1 case (1.4%). In 59 cases, only the arterial phase of the enhanced dual-phase scan images showed the optimal manifestation of the duodenal
Table 1 Association between the duodenal papilla size and patient characteristics. Category
Number of cases
Gender Male 36 Female 34 Age group Young 42 Middle-age 18 Senior 10 Papilla morphology Round-like 37 Hemispherical 18 Conic 10 Flat 5 Ampulla of Vater type Y 51 V 17 U 2
Base diameter (mm)
Height (mm)
7.5 ± 1.2 7.1 ± 1.7
6.5 ± 2.1 6.6 ± 1.5
7.1 ± 1.6 7.5 ± 1.3 7.8 ± 1.0
6.2 ± 1.8 7.2 ± 2.0 6.8 ± 1.1
7.4 7.8 6.5 5.9
± ± ± ±
1.2 1.3 1.8 1.2
7.2 ± 1.4 7.6 ± 1.4 7.6 ± 2.7
7.1 5.9 7.8 2.4
± ± ± ±
1.3 1.4 1.2 0.5
6.5 ± 1.7 6.5 ± 2.2 6.9 ± 0.0
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type (72.9%), 17 cases of the V type (24.3%) and 2 cases of the U type (2.9%). The base diameter of the duodenal papilla between the Y type and the V type was not significantly different (t = −1.066, P = 0.290). Neither was the height (t = 0.152, P = 0.879). Moreover, the distribution of the Y and V types among the observed 4 types was not significantly different (2 = 3.629, P = 0.304). Notably, the number of the U type case was too small for statistical analysis). 4. Discussion
Fig. 3. Measurement of the size of the duodenal papilla. The base diameter is the maximal diameter of the duodenal papilla by measuring the tangent parallel with the duodenal medial wall. The height is the maximal papilla diameter obtained by measuring the tangent perpendicular to the medial wall.
papilla (84.3%), whereas in 4 cases, only the venous phase showed the optimal manifestation (5.7%). In the other 7 cases, the arterial and the venous phases were equally good for the observation of the duodenal papilla (10%). Using the density of the contrast enhanced duodenal mucosal plicae in the same slice as the reference, duodenal papilla was isodense in all of the 70 cases (100%). No low-density or high-density duodenal papilla was observed in the enhanced scan images of our patients. The “target sign” was clearly identified on arterial phase images in 50 of 70 patients (71.4%, Fig. 5), but not in the other 20 cases (28.6%). The type of the ampulla of Vater and the corresponding duodenal papilla size are listed in Table 1, including 51 cases of the Y
The size, location, and morphological of normal duodenal papillae, as well as configurations of ampulla of Vater were generally in accordance with those reported before [1,7,8]. Our series did have less number of papillae located in the horizontal duodenum than in some previous reports, 1.4% vs up to 25% [7,8]. There are 3 types of configuration of ampulla of Vater, the Y, V and U shapes. The Y shaped one is the commonest, 72.9% in our series, almost the same as reported previously by Mirilas et al. [8]. In addition, we found that the distribution of the configuration of ampulla of Vater was not significantly different amongst the duodenal papilla of different size and morphology. In the far majority of our cases (94.3%), the arterial phase images were the best for the visualization of the duodenal papilla, likely due to the fact that duodenal mucosa over the papilla showed better enhancement and higher contrast relative to ampulla of Vater and adjacent soft tissues during the arterial phase. The “target sign” produced by enhancing mucosal layer over the underlying hypodense ampulla of Vater [5] was clearly identified in 71.4% of our cases, all in the arterial phase images, which is helpful for the identification of the normal papilla. It was also shown that all duodenal papillae appear isodense with reference to mucosal plicae in the same slice. Therefore we propose that arterial phase scan be used for assessment of duodenal papillae, and that they should be isodense to adjacent mucosal plicae.
Fig. 4. Morphological type of the duodenal papilla in enhanced arterial phase CT scan images (arrow). (1) Round-like; (2) Hemispheric; (3) Conical; (4) Flat.
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further assessed for pathological lesions when duodenal papilla is larger than 10 mm in size. However, this threshold might not apply for thick slice images due to partial volume averaging effect with surrounding mucosal plicae. Therefore, thin-slice images, together with the coronal images, should be used for proper evaluation of the duodenal papilla. Using axial CT images, previous researchers have reported 3 types of papilla morphology: round, hemispherical and flat [7,8]. We have observed an additional conical morphological type in 14.3% of our cases. Across all different morphological types, these normal papillae all show smooth margins without any lobulation. Therefore, smooth margin constitutes another criteria for normal papilla. There are some limitations to the present study. Firstly, the patients were selected on the basis of normal manifestations on edoscopy. However, this may not be true as endoscopy can miss small submucosal lesions. Secondly, adequate duodenal distension was requisite for displaying the papilla. We have not evaluated effect of different CT protocols (such as use of different patient positioning and hypotonic agents) in this retrospective study. In conclusion, arterial phase contrast enhanced MDCT can be used for accurate evaluation of duodenal papilla, providing important information for discerning early pathological changes. This study also provides a reference for the normal size and morphology of the papilla on MDCT. A good knowledge of the normal appearance will make it less likely for pathological abnormalities to be missed. It may also prevent over reporting of normal findings e.g. the conical papilla. Moreover, our study provided useful reference data for location of duodenal papilla, useful for the endoscopic retrograde cholangiopancreatography and biliary pancreatic surgery. References
Fig. 5. Target sign. (1) The “target sign” of the duodenal papilla on an enhanced arterial phase CT scan images. (2) The venous phase CT scan images at the same slice from the same patient, showing less contrasted density of this region and the disappearance of the “target sign”.
The size normal duodenal papillae as measured in this study were all less than 10 mm across different morphological types. This is in accordance with the maximal diameter of 5–10 mm reported by Kim et al. [5] and Fukukura et al. [6], based on their analysis of axial CT images, and the report by Avisse et al. [7] using clinical samples. Therefore, we propse that patients should be
[1] Horiguchi S, Kamisawa T. Major duodenal papilla and its normal anatomy. Digestive Surgery 2010;27:90–3. [2] Frierson Jr HF. The gross anatomy and histology of the gallbladder, extrahepatic bile ducts. American Journal of Surgical Pathology 1989;13:146–62. [3] Guo ZJ, Chen YF, Zhang YH, et al. CT virtual endoscopy of the ampulla of Vater: preliminary report. Abdominal Imaging 2011;36:514–9. [4] Kamisawa T, Tu Y, Nakajima H, et al. The presence of a common channel and associated pancreaticobiliary diseases: a prospective ERCP study. Digestive and Liver Disease 2007;39:273–9. [5] Kim S, Lee NK, Lee JW, et al. CT evaluation of the bulging papilla with endoscopic correlation. RadioGraphics 2007;27:1023–38. [6] Fukukura Y, Fujiyoshi F, Sasaki M, et al. Intraductal papillary mucinous tumors of the pancreas: thin-section helical CT findings. American Journal of Roentgenology 2000;174:441–7. [7] Avisse C, Flament JB, Delattre JF. Ampulla of Vater: anatomic, embryologic, and surgical aspects. Surgical Clinics of North America 2000;80:201–12. [8] Mirilas P, Colborn GL, Skandalakis LJ, et al. Benign anatomical mistakes:“ampulla of Vater” and “papilla of Vater”. American Surgeon 2005;71:269–74.
Contents lists available at SciVerse ScienceDirect
European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad
Multidetector computed tomography (MDCT) manifestations of the normal duodenal papilla Can-Hui Sun a,1 , Xuehua Li a,1 , Tao Chan b,1 , Zhenpeng Peng a,1 , Zhi Dong a,1 , Yanji Luo a,1 , Zi-Ping Li a,1 , Shi-Ting Feng a,∗,1 a b
Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China Medical Imaging Department, Union Hospital, Hong Kong
a r t i c l e
i n f o
Article history: Received 25 September 2012 Received in revised form 9 December 2012 Accepted 2 January 2013 Keywords: Duodenal papilla Tomography X-ray computed tomography
a b s t r a c t Objective: This study aimed to investigate Multidetector Computed Tomography (MDCT) manifestations of the normal duodenal papilla, thereby improving the knowledge on the CT manifestations of the normal anatomy of the duodenal papilla. Methods: A retrospective study was conducted by reviewing the CT results of 70 normal duodenal papilla cases examined by 64-MDCT. The analysis particularly focused on the position, size, morphology, and enhancement pattern of the duodenal papilla, as well as the ampulla of Vater. Results: In axial images, the average base diameter of the duodenal papilla was (7.3 ± 1.4) mm, whereas the average height was (6.5 ± 1.8) mm. Majority of the duodenal papilla (52.9%, 37/70) showed a round shape. In most cases (97.1%, 68/70), the duodenal papilla were located at the middle and lower third of the descending duodenum. In 84.3% of the cases (59/70), the arterial phase enhanced CT scan images were optimal for the visualization of the papilla. The “target sign” could be clearly identified from arterial phase images in 71.4% (50/70) of the cases. In 72.9% (51/70) of the cases, the ampulla of Vater had a common channel (Y type). Conclusion: 64-MDCT can clearly visualize the normal anatomy of the duodenal papilla and surrounding structures, thereby providing valuable information for the diagnosis and treatment of diseases in this region. © 2013 Elsevier Ireland Ltd. All rights reserved.
1. Introduction The duodenal papilla is the papillary structure formed by the elevation of the duodenal mucosal plicae toward the lumen [1–3]. Being the connecting point between the liver, gallbladder, pancreas and intestines, pathological changes in the duodenal papilla can induce a series of diseases involving these major organs; sometimes, even systemic diseases may occur [2,4]. Moreover, different types of lesions could lead to different characteristic morphological changes of the duodenal papilla. CT examination,
∗ Corresponding author at: Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, 58th, The Second Zhongshan Road, Guangzhou, Guangdong, China. Tel.: +86 20 87755766x8471; fax: +86 20 87615805. E-mail addresses: [email protected] (C.-H. Sun), [email protected] (X. Li), [email protected] (T. Chan), [email protected] (Z. Peng), [email protected] (Z. Dong), [email protected] (Y. Luo), [email protected] (Z.-P. Li), [email protected], [email protected] (S.-T. Feng). 1 All authors actively participated in this study. Drs Can-Hui Sun and Xuehua Li wrote the manuscript. Shi-Ting Feng conceived the conception and design of the study, Zhenpeng Peng performed acquisition of data, Zhi Dong and Yanji Luo performed interpretation of data, Zi-Ping Li performed statistical analysis, Tao Chan revised and reviewed the article for important intellectual content. All authors had full access to the data obtained, and all approved the final manuscript. 0720-048X/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ejrad.2013.01.007
especially multiple-slice spiral CT, can accurately reveal the structural changes in the duodenal papilla, as well as the relationship between these lesions and the surrounding tissues, thereby playing an increasingly important role in diagnosis [2]. Due to significant variability of the duodenal papilla anatomy, accurate knowledge about normal appearances of the duodenal papilla is crucial for diagnosis of pathological events in this region. Many researchers have studied the anatomy of duodenal papilla using approaches including dissection examination and endoscopy. However, there have only been a few reports regarding the imaging manifestations of the duodenal papilla [4–8], and no systematic evaluation of the normal anatomy on MDCT has been reported before. In the present study, we analyzed 70 normal duodenal papilla using 64-MDCT, to improve the knowledge on the CT manifestations of the normal anatomy of the duodenal papilla 2. Material and methods 2.1. Patients All adult patient who had undergone both dual phase contrast enhanced MDCT of upper abdomen and endoscopy within a 3 day interval during the period from September 2009 and October 2010
C.-H. Sun et al. / European Journal of Radiology 82 (2013) 918–922
919
were retrospectively retrieved from our PACS. From these, subjects of the current study were selected based on the following criteria: (1) no pathological lesions or congenital abnormalities in the liver, gallbladder, pancreas, duodenum or the surrounding regions, such as peri-ampullary duodenal diverticula; (2) no duodenal filling defects (isotonic mannitol solution was used to distend the duodenum) and clear visibility of the duodenal papilla against the fluid and gas around the region; (3) no abnormality of duodenal papilla as revealed on endoscopy. Altogether 70 cases were analyzed in the current study, consisting of 36 males and 34 females, age ranged from 20 to 80 years, with the mean age of 41.5 years. The subjects were divided into 3 age groups, including 42 cases in the young adult group (≤39 years), 18 cases in the middle-aged group (40–59 years) and 10 cases in the elderly group (≥60 years). This study was HIPAA compliant and informed consent was waived by the IRB. 2.2. CT protocols Plain and dual-phase enhanced 64-MDCT was performed through the epigastric region using a Toshiba Aquilion 64-slice CT scanner (Tokyo, Japan). The parameters used were as follows: tube voltage – 120 kV, tube current – 200 mA, matrix – 512 × 512, slice thickness – 64 × 0.5 mm, spiral pitch-0.828, scanning range: from the top of the diaphragm to below inferior edge of the horizontal segment of the duodenum. Contrast agent (Ultravist 300, Bayer Healthcare Pharmaceuticals, Berlin, German) was used as the intravenous contrast agent, at the dose 1.5 ml/kg body weight, and the injection rate of 3.5 ml/s. The arterial phase CT scan was started at 32 s post-injection, whilst the venous phase scan was initiated at 65 s post-injection. The patients underwent a routine fasting for 8 h and were orally administered with 900 ml of the isotonic mannitol solution (2.5%) at 30 min prior to the scan. Right before the scan, they were orally administered with 300 ml of the isotonic mannitol solution (2.5%) to dilate the stomach and the duodenum. In order to fully dilate the descending duodenum, the patients were instructed to lie down on the right side 1–2 min before the scan and to lie on the back during the scan. For the purpose of analyzing the morphology and size of the duodenal papilla at its natural state, we did not use hypotonic agents in this study. 2.3. Observation method and items The obtained CT volume data were reformatted with slice distance of 1 mm and slice thickness of 0.5 mm, and were transmitted to the HP workstation XW8200 (Vitrea 2, version3.7) for further analysis. Images were examined by two experienced abdominal radiologists independently. The assessment that they both agreed on was considered the final result. The junction of the bile and pancreatic ducts (ampulla of Vater) was identified from the CT using the method of curved multiplanar reformation (cMPR). By tracing the ampulla of Vater to the papillary structure formed by the elevation of the duodenal mucosal plicae toward the lumen, the duodenal papilla is located (Fig. 1). The slice on which the papilla appears largest was selected for further comprehensive analysis. Based on the manifestations on the axial images, there were 4 morphological types of the duodenal papilla, i.e., round, hemispheric, conical and flat (Fig. 2). The phase of contrast enhanced CT in which the duodenal papilla was best visualized was chosen for size measurements. When both the arterial phase and the venous phase qualified for the optimal visualization, arterial phase images were used, due to the fact that majority of the other cases showed better visualization on the arterial phase. The measurements were obtained as follows. The base diameter was determined as the maximal papilla
Fig. 1. cMPR of the ampulla of Vater. In the enhanced arterial phase CT scan images, the ends of the main bile duct (the thick short arrow) and the main pancreatic duct (the thick long arrow) form the Y type ampulla of Vater, obliquely entering the descending duodenum by penetrating the medial wall to the papilla (the thin arrow).
diameter, obtained by measuring the tangent parallel with the duodenal medial wall, in the maximal slice of the axial thin-slice images (1.0 mm). The height was determined as the maximal papilla diameter obtained by measuring the tangent perpendicular to the medial wall (Fig. 3). Also, the duodenal lumen diameter was measured from the same slice. According to the appearances on coronal images, positions of the duodenal papilla were divided into 4 types: upper third of the descending duodenum, the middle third of the descending duodenum, the lower third of the descending duodenum and the horizontal duodenum. In the enhanced arterial phase images, density of the duodenal papilla was measured and compared against that of the duodenal mucosal plicae in the same slice. We defined the density of the duodenal papilla as isodensity, lowdensity, or high-density when it was equal to, lower or higher than that of adjacent mucosal plicae. The “target sign” was defined as the appearance produced the relatively lower density in the center and higher density at the border of the duodenal papilla on enhanced images. According to the relationship between pancreatic duct and common bile duct, the configuration of ampulla of Vater was classified into tree major types: Y type, V type and U type. 2.4. Statistical analysis The software package SPSS 13.0 was used for statistical analyses of the data. Comparison among size in different age groups of diameter was conducted using one-way analysis of variance. Comparison of size between two groups was conducted using the two independent sample t-test. Distribution of different types of configuration of ampulla of Vater was compared using the chi-square test. The difference was considered statistically significant when P < 0.05. 3. Results The maximal luminal diameter at the level of the duodenal papilla was (22.9 ± 1.5) mm. Of the 70 cases, the average base diameter of the duodenal papilla was (7.3 ± 1.4) mm, whereas the average height was (6.5 ± 1.8) mm. The upper limit values at 95% CI of these two parameters were 9.6 mm and 9.5 mm respectively. No statistically significant difference was found in these
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C.-H. Sun et al. / European Journal of Radiology 82 (2013) 918–922
Fig. 2. Morphological type of the duodenal papilla (model). (1) Round-like; (2) Hemispheric; (3) Conical; (4) Flat.
measurements between the males and females (base diameter: t = 1.136, P = 0.260; height: t = −0.112, P = 0.911). Moreover, no statistically significant difference was observed amongst the young, middle-aged and senior groups, regarding the base diameter or height of the duodenal papilla (F = 1.318, P = 0.275 and F = 1.942, P = 0.151, respectively; Table 1). The morphology of the duodenal papilla could be categorized as 4 types: round, hemispheric, conical and flat (Fig. 4). Among the 70 cases, the percentage of each morphological type was as follows: 52.9%-round, 25.7%-hemispheric, 14.3%-conical and 7.1%-flat. The size of each type of papilla is listed in Table 1. The distribution of these 4 morphological types between male and female was not statistically different (2 = 2.842, P = 0.417). Among the 70 cases, the duodenal papilla was located in the upper third of the descending duodenum in 1 case (1.4%), in the middle third of the descending duodenum in 56 cases (80.0%), in the lower third of the descending duodenum in 12 cases (17.1%) and in the horizontal duodenum in 1 case (1.4%). In 59 cases, only the arterial phase of the enhanced dual-phase scan images showed the optimal manifestation of the duodenal
Table 1 Association between the duodenal papilla size and patient characteristics. Category
Number of cases
Gender Male 36 Female 34 Age group Young 42 Middle-age 18 Senior 10 Papilla morphology Round-like 37 Hemispherical 18 Conic 10 Flat 5 Ampulla of Vater type Y 51 V 17 U 2
Base diameter (mm)
Height (mm)
7.5 ± 1.2 7.1 ± 1.7
6.5 ± 2.1 6.6 ± 1.5
7.1 ± 1.6 7.5 ± 1.3 7.8 ± 1.0
6.2 ± 1.8 7.2 ± 2.0 6.8 ± 1.1
7.4 7.8 6.5 5.9
± ± ± ±
1.2 1.3 1.8 1.2
7.2 ± 1.4 7.6 ± 1.4 7.6 ± 2.7
7.1 5.9 7.8 2.4
± ± ± ±
1.3 1.4 1.2 0.5
6.5 ± 1.7 6.5 ± 2.2 6.9 ± 0.0
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type (72.9%), 17 cases of the V type (24.3%) and 2 cases of the U type (2.9%). The base diameter of the duodenal papilla between the Y type and the V type was not significantly different (t = −1.066, P = 0.290). Neither was the height (t = 0.152, P = 0.879). Moreover, the distribution of the Y and V types among the observed 4 types was not significantly different (2 = 3.629, P = 0.304). Notably, the number of the U type case was too small for statistical analysis). 4. Discussion
Fig. 3. Measurement of the size of the duodenal papilla. The base diameter is the maximal diameter of the duodenal papilla by measuring the tangent parallel with the duodenal medial wall. The height is the maximal papilla diameter obtained by measuring the tangent perpendicular to the medial wall.
papilla (84.3%), whereas in 4 cases, only the venous phase showed the optimal manifestation (5.7%). In the other 7 cases, the arterial and the venous phases were equally good for the observation of the duodenal papilla (10%). Using the density of the contrast enhanced duodenal mucosal plicae in the same slice as the reference, duodenal papilla was isodense in all of the 70 cases (100%). No low-density or high-density duodenal papilla was observed in the enhanced scan images of our patients. The “target sign” was clearly identified on arterial phase images in 50 of 70 patients (71.4%, Fig. 5), but not in the other 20 cases (28.6%). The type of the ampulla of Vater and the corresponding duodenal papilla size are listed in Table 1, including 51 cases of the Y
The size, location, and morphological of normal duodenal papillae, as well as configurations of ampulla of Vater were generally in accordance with those reported before [1,7,8]. Our series did have less number of papillae located in the horizontal duodenum than in some previous reports, 1.4% vs up to 25% [7,8]. There are 3 types of configuration of ampulla of Vater, the Y, V and U shapes. The Y shaped one is the commonest, 72.9% in our series, almost the same as reported previously by Mirilas et al. [8]. In addition, we found that the distribution of the configuration of ampulla of Vater was not significantly different amongst the duodenal papilla of different size and morphology. In the far majority of our cases (94.3%), the arterial phase images were the best for the visualization of the duodenal papilla, likely due to the fact that duodenal mucosa over the papilla showed better enhancement and higher contrast relative to ampulla of Vater and adjacent soft tissues during the arterial phase. The “target sign” produced by enhancing mucosal layer over the underlying hypodense ampulla of Vater [5] was clearly identified in 71.4% of our cases, all in the arterial phase images, which is helpful for the identification of the normal papilla. It was also shown that all duodenal papillae appear isodense with reference to mucosal plicae in the same slice. Therefore we propose that arterial phase scan be used for assessment of duodenal papillae, and that they should be isodense to adjacent mucosal plicae.
Fig. 4. Morphological type of the duodenal papilla in enhanced arterial phase CT scan images (arrow). (1) Round-like; (2) Hemispheric; (3) Conical; (4) Flat.
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further assessed for pathological lesions when duodenal papilla is larger than 10 mm in size. However, this threshold might not apply for thick slice images due to partial volume averaging effect with surrounding mucosal plicae. Therefore, thin-slice images, together with the coronal images, should be used for proper evaluation of the duodenal papilla. Using axial CT images, previous researchers have reported 3 types of papilla morphology: round, hemispherical and flat [7,8]. We have observed an additional conical morphological type in 14.3% of our cases. Across all different morphological types, these normal papillae all show smooth margins without any lobulation. Therefore, smooth margin constitutes another criteria for normal papilla. There are some limitations to the present study. Firstly, the patients were selected on the basis of normal manifestations on edoscopy. However, this may not be true as endoscopy can miss small submucosal lesions. Secondly, adequate duodenal distension was requisite for displaying the papilla. We have not evaluated effect of different CT protocols (such as use of different patient positioning and hypotonic agents) in this retrospective study. In conclusion, arterial phase contrast enhanced MDCT can be used for accurate evaluation of duodenal papilla, providing important information for discerning early pathological changes. This study also provides a reference for the normal size and morphology of the papilla on MDCT. A good knowledge of the normal appearance will make it less likely for pathological abnormalities to be missed. It may also prevent over reporting of normal findings e.g. the conical papilla. Moreover, our study provided useful reference data for location of duodenal papilla, useful for the endoscopic retrograde cholangiopancreatography and biliary pancreatic surgery. References
Fig. 5. Target sign. (1) The “target sign” of the duodenal papilla on an enhanced arterial phase CT scan images. (2) The venous phase CT scan images at the same slice from the same patient, showing less contrasted density of this region and the disappearance of the “target sign”.
The size normal duodenal papillae as measured in this study were all less than 10 mm across different morphological types. This is in accordance with the maximal diameter of 5–10 mm reported by Kim et al. [5] and Fukukura et al. [6], based on their analysis of axial CT images, and the report by Avisse et al. [7] using clinical samples. Therefore, we propse that patients should be
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