Published online before print May 5, 2008, 10.1148/radiol.2481071156
(Radiology 2008;248:124-131.)
© RSNA, 2008
Cystic Artery and Cystic Duct Assessment with 64–Detector Row CT before Laparoscopic Cholecystectomy1
Reiji Sugita, MD,
Tetsuro Yamazaki, MD,
Naotaka Fujita, MD,
Tsuyoshi Naitoh, MD,
Masao Kobari, MD, and
Shoki Takahashi, MD
1 From the Departments of Radiology (R.S.), Gastroenterology (N.F.), and Surgery (T.N., M.K.), Sendai City Medical Center, 5-22-1 Tsurugaya, Miyangino-ku, Sendai, Miyagi 983-0824, Japan; Department of Radiology, Nippon Telephone and Telegraph East Tohoku Hospital, Sendai, Miyagi, Japan (T.Y.); and Department of Diagnostic Radiology, Tohoku University, Graduate School of Medicine, Sendai, Miyagi, Japan (S.T.). Received July 3, 2007; revision requested August 30; revision received November 2; accepted January 14, 2008; final version accepted January 31.
Address correspondence to R.S. (e-mail: rsugita{at}openhp.or.jp).
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ABSTRACT
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Purpose: To retrospectively assess 64–detector row computed tomography (CT) in the preoperative depiction of the cystic duct and cystic arteries in and around the Calot triangle.
Materials and Methods: Institutional review board approval was obtained, with waiver of informed consent. A total of 245 consecutive patients (133 men, 112 women), including 48 patients who subsequently underwent cholecystectomy, were examined. Two independent observers evaluated the CT data set on the basis of axial sections, coronal and sagittal multiplanar reformations, and three-dimensional volume rendering. The relationship between the cystic arteries and the Calot triangle—which is bordered by the undersurface of the liver, common hepatic duct, and cystic duct—was also evaluated, and each patient was classified on the basis of the origin of the cystic arteries and the course to the Calot triangle. Statistical analysis was performed, and percentages and confidence intervals were calculated.
Results: The cystic arteries were delineated in 234 of the 245 patients. Both the Calot triangle and the cystic arteries were delineated in 223 patients. One cystic artery was seen in the Calot triangle in 173 patients, and two cystic arteries were seen in the Calot triangle in 12. One artery in the Calot triangle with accessory arteries from different origins outside the Calot triangle was seen in 18 patients, and no cystic artery was identified in 20. Cystic arteries were seen in 42 (92%; 95% confidence interval: 87%, 98%) of the 48 patients who subsequently underwent cholecystectomy. The relationship between the cystic arteries and the Calot triangle was in agreement with the surgical records for all patients.
Conclusion: The configuration of the cystic duct and cystic arteries can be depicted preoperatively with 64–detector row CT in patients scheduled to undergo cholecystectomy.
© RSNA, 2008
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INTRODUCTION
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Laparoscopic cholecystectomy has become a common procedure used to treat gallbladder stones in patients who do not have an associated disease in the vicinity of the lesions (1–5); however, complications of this procedure remain a problem (6–16). This surgical procedure requires careful blunt dissection of the Calot triangle, which is also known as the hepatobiliary triangle (1). This triangle is bordered by the undersurface of the liver, the common hepatic duct, and the cystic duct, within which minute cystic arteries frequently are found (1–5).
Among the anatomic structures in and around the Calot triangle, both the common hepatic duct and the cystic duct that border the triangle can be assessed preoperatively with drip-infusion cholangiography, computed tomography (CT) cholangiography, or magnetic resonance (MR) cholangiopancreatography (17–20). Comprehension of the course of the cystic arteries that run within or near the Calot triangle is also desirable before laparoscopic cholecystectomy is performed because inadvertent injury to these arteries can cause uncontrollable bleeding under the limited field of view of laparoscopic surgery (1–5).
The development of multidetector row CT has made it possible to clearly depict even the peripheral vascular system (21–25) and the extrahepatic bile duct (17). However, to our knowledge, there have been few studies in which researchers have focused on the depiction of both the cystic arteries and the cystic duct (25). Thus, the purpose of our study was to retrospectively assess 64–detector row CT in the preoperative depiction of the cystic duct and cystic arteries in and around the Calot triangle.
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MATERIALS AND METHODS
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Patients
Institutional review board approval was obtained, with waiver of informed consent. Between May 2005 and April 2006, 245 consecutive patients (133 men, 112 women; mean age, 61.6 years; age range, 20–79 years) who were referred to our institution for various upper abdominal diseases were examined with 64–detector row CT over an area that covered the entire liver. Clinical diagnoses were as follows: abdominal discomfort (n = 73), cholecystolithiasis (n = 50), hepatocellular carcinoma (n = 22), pancreas cyst (n = 14), hepatic hemangioma (n = 13), cirrhosis (n = 11), liver cyst (n = 11), pancreatic cancer (n = 10), liver tumor (n = 10), and other abdominal diseases (n = 31). Forty-eight patients (21 men, 27 women; mean age, 45.2 years; age range, 28–77 years) underwent cholecystectomy because of gallstones: Forty patients underwent laparoscopic cholecystectomy. The remaining eight patients underwent open surgery because they were suspected of having adhesions on the basis of preoperative CT findings, such as proliferation of the soft tissue surrounding the gallbladder or history of previous abdominal surgery. The interval between CT and surgery ranged from 2 to 50 days (mean, 24 days).
CT Examination
CT was performed with a 64–detector row scanner (Aquillion; Toshiba, Tokyo, Japan). Scanning was performed with the following parameters: 120 kV, 350 mAs, 0.5 second per rotation, 0.5-mm collimation, and 0.828 beam pitch. All patients underwent craniocaudal scanning in the supine position during a single breath hold. All patients received 100 mL (total, 30 g) of nonionic contrast material at a concentration of 300 mg of iodine per milliliter (iopamidol, Iopamilon 300; Schering, Berlin, Germany), which was administered intravenously via the right antecubital vein through a 20-gauge catheter at a rate of 3 mL/sec by using an automated injector (Dualshot; Nemoto, Tokyo, Japan). An automatic bolus-triggering software program was systematically applied, with a circular region of interest positioned from the aorta at the level of bifurcation of the celiac artery, and the threshold for triggering data acquisition was preset at 100 HU to determine the scanning delay for arterial phase imaging.
CT Image Interpretation
CT images obtained in all 245 patients were retrospectively reviewed to assess the depiction of the cystic arteries and cystic duct. For analysis of CT findings, the stored raw data of the 0.5-mm-thick transverse CT images were transferred to a workstation (Zio Volume Grid; Amin, Tokyo, Japan). From each data set, the following four series of images were systematically reconstructed: contiguous 1-mm-thick transverse, coronal, and sagittal images, as well as three-dimensional volume-rendered images of the abdominal vascular structures. Without knowledge of the surgical findings, two radiologists (R.S., T.Y.; each had 17 years of clinical experience) independently and retrospectively evaluated the images, which were presented in a random fashion, and identified the cystic arteries, the origin of the cystic arteries, and the cystic duct. This evaluation was performed over a 2-month period (approximately 10 studies were evaluated at a time). In the event of disagreement over the evaluation results, the two radiologists discussed the findings to reach a consensus.
Cystic arteries.—Nodular and curvilinear enhanced structures around the gallbladder and joining the common hepatic artery or its major branches were sought and regarded as cystic arteries, when present. To trace their origin to their parent arteries, additional maximum intensity projection images of arbitrary thickness (1–10 mm) were often used. We evaluated the number and traceability (clear depiction of the vessels over their full length) of the cystic arteries. Traceability was graded on a scale of 0–2: We assigned a score of 2 (excellent traceability) when the cystic artery was traceable through the full length of the vessel, from the origin to beyond the neck of the gallbladder; a score of 1 (fair traceability) when the cystic artery was only partially traceable; and a score of 0 (poor traceability) when the cystic artery was untraceable. We also evaluated enhancement of the infrarenal inferior vena cava to assess the timing of contrast material administration.
Cystic duct.—The common bile duct was identified as a clublike low-attenuation area (attenuation was slightly higher than that of the surrounding fat) that extended in a straight or oblique craniocaudal direction. A curvilinear structure that connected the common bile duct and the gallbladder and had a similar attenuation was regarded as the cystic duct (26,27). Visibility of the cystic duct was also graded on a scale of 0–2: A score of 2 (excellent visibility) indicated sharp delineation; a score of 1 (fair visibility), somewhat blurred delineation; and a score of 0 (poor visibility), no delineation. Additionally, the cystic duct was categorized as one of five types according to the classification of Ichii et al (28), which was based on the course of the cystic duct and the location of the confluence to the common bile duct (Fig 1).
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Figure 1: Diagram shows cystic duct classification based on the course of the cystic duct and the location of the confluence to the common bile duct. First, cystic ducts are divided into three types: type I, intrahepatic union when the cystic duct joins the hepatic duct superior to the junction of both hepatic ducts; type II, middle union when the cystic duct joins the common bile duct between the junction of both hepatic ducts and the beginning of the intrapancreatic common bile duct; and type III, intrapancreatic union when the cystic duct joins the intrapancreatic common bile duct. Type II cystic ducts are further classified into the following three subtypes based on the course of the duct and the side of confluence to the common bile duct: type IIa, ipsilateral (on the same side of the gallbladder); type IIb, anterior contralateral (on the opposite side of the gallbladder); and type IIc, posterior contralateral.
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Relationship of cystic arteries to the Calot triangle.—We evaluated the relationship between the cystic arteries and the Calot triangle (more specifically, the relationship between the common hepatic duct and the cystic duct). Patients without any identifiable cystic artery (score 0) or without any identifiable cystic duct (score 0) were excluded from this evaluation. The relationship was categorized as one of several types according to the modified classification of Suzuki et al (1) (Fig 2): Types 1, 2, and 3 represented one cystic artery, two cystic arteries, and three or more cystic arteries, respectively.
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Figure 2: Diagram shows cystic artery classification based on the relationship of the cystic artery to the Calot triangle. Cystic arteries can be classified into seven subtypes on the basis of their relationship to the Calot triangle, which consists of the common hepatic duct, cystic duct (CD), and undersurface of the liver (L), and within which minute arteries frequently may be found. Types 1, 2, and 3 are associated with one cystic artery (CA), two cystic arteries, and three or more cystic arteries, respectively. Each is further subdivided as follows: Type 1a indicates one cystic artery courses at least partly through the Calot triangle. Type 1b indicates one cystic artery courses outside the Calot triangle. Type 2a indicates two cystic arteries course at least partly through the Calot triangle. Type 2b indicates one artery courses at least partly through the Calot triangle and the other artery courses outside the Calot triangle. Type 2c indicates both cystic arteries course entirely outside the Calot triangle. Type 3a indicates all arteries course through the Calot triangle. Type 3b indicates all but one artery course at least partly through the Calot triangle, while the remaining artery courses outside the Calot triangle. Type 3c (not shown) indicates two or more arteries course outside the Calot triangle. CBD = common bile duct, GB = gallbladder.
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Comparison of CT Findings and Surgical Records
In 48 patients who subsequently underwent cholecystectomy, the cystic arteries and the cystic duct were identified in the retrospective review of preoperative CT images. When both cystic arteries and the Calot triangle were identified, their relationship was compared by a radiologist (R.S.) and a surgeon (T.N., 17 years experience) who reviewed surgical records in consensus. For this purpose, the surgeon reviewed videos recorded in the 40 patients who underwent laparoscopic cholecystectomy.
Statistical Analysis
For patients who underwent cholecystectomy, percentages and 95% confidence intervals were calculated to demonstrate the randomness of the sample size for patients in whom the cystic arteries were depicted and for those in whom both the cystic arteries and the cystic duct were depicted. The 
statistic was used to assess interobserver variability in image interpretation between the observers. Statistical data were calculated by using commercially available software (SAS, version 8.02; SAS Institute, Cary, NC).
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RESULTS
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Cystic Arteries
In 234 (96%) of the 245 patients, the cystic arteries were at least partially delineated on CT images. The full length of at least one cystic artery was traceable from its origin to beyond the neck of the gallbladder in 220 patients, whereas the full length of at least one cystic artery was only partially traceable in 14 patients. One cystic artery was found in 189 (81%) of the 234 patients, two cystic arteries were found in 45 (19%) patients, and three or more arteries were not found in any patients. Thus, a total of 279 cystic arteries were found in the 245 patients. Classification of the origins of the cystic artery is summarized in Table 1. The average traceability score of the cystic artery was 1.9. The cystic artery was unidentifiable in 11 of the 245 patients: In three of these patients, the organ contours were generally obscured, probably because of motion artifacts. In two patients, the fat around the gallbladder had a high attenuation, indicating inflammatory changes. In the remaining six patients, enhancement of the infrarenal inferior vena cava was noted, which means there was a delay in contrast material administration. There was disagreement that needed to be resolved by consensus reading in 28 (11%) of the 245 patients (average traceability score, 1.6), while the patients with agreement had an average score of 2.0. A value of 0.88 for agreement between the two observers was obtained, and interobserver agreement was almost perfect.
Cystic Duct
The cystic duct, a component of the Calot triangle, was detected at CT in 233 (95%) of 245 patients. Among them, the cystic duct was clearly delineated (score 2) in 145 patients, while it was blurred (score 1) in 88. The average traceability score was 1.6. The cystic duct anatomy according to the union and course is shown in Table 2. Of the 245 patients, 55 (22%) in whom there was disagreement that needed to be resolved by consensus reading had an average score of 1.0, while the others in whom there was agreement had an average score of 1.7. Interobserver agreement was substantial ( = 0.77).
Relationship of Cystic Arteries to Calot Triangle
Both the Calot triangle and the cystic arteries were identifiable in 223 (91%) of the 245 patients. In the remaining 22 patients, either the cystic duct (n = 11) or the cystic arteries (n = 10) were not identified. In one patient, neither the cystic duct nor the cystic arteries were identified. The relationship between the cystic arteries and the Calot triangle (Fig 2) was as follows: type 1a in 173 patients (78%) (Fig 3), type 1b in 20 patients (9%) (Fig 4), type 2a in 12 patients (5%), and type 2b in 18 patients (8%) (Table 3).
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Figure 3: Thick-slab maximum intensity projection CT image in a 79-year-old woman with cholecystolithiasis shows the type 1a relationship between the cystic artery (arrowhead), common bile duct (CBD), and cystic duct (CD). The cystic artery originates from the right hepatic artery (large arrow) and reaches the gallbladder (GB) wall through the Calot triangle (thin broken line).
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Figure 4a: Images show a type 1b relationship between the cystic artery and the Calot triangle in a 72-year-old woman. (a) Coronal black-and-white-reversed CT image obtained with a narrow window setting. In our routine clinical practice, this type of image is made for surgeons to depict the relationship between the cystic artery and the Calot triangle. In reality, CT image evaluation regarding the relationship between the cystic arteries, common bile duct (CBD), and cystic duct (CD) was performed with the paging method and abdominal window settings. GB = gallbladder. (b) Original window setting display image of a. (c, d) Thick-slab maximum intensity projection CT images show the relationship between the cystic artery (arrowheads) and the common bile duct. The cystic artery originates from the left hepatic artery (arrow) and reaches the gallbladder wall by coursing outside the Calot triangle (thin broken line). L = liver, PV = portal vein. (e) Composite drawing of a, c, and d shows the relationship between the cystic artery (arrowheads), which originates from the left hepatic artery (large arrow), and the Calot triangle. PHA = proper hepatic artery, RH = right hepatic artery.
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Figure 4b: Images show a type 1b relationship between the cystic artery and the Calot triangle in a 72-year-old woman. (a) Coronal black-and-white-reversed CT image obtained with a narrow window setting. In our routine clinical practice, this type of image is made for surgeons to depict the relationship between the cystic artery and the Calot triangle. In reality, CT image evaluation regarding the relationship between the cystic arteries, common bile duct (CBD), and cystic duct (CD) was performed with the paging method and abdominal window settings. GB = gallbladder. (b) Original window setting display image of a. (c, d) Thick-slab maximum intensity projection CT images show the relationship between the cystic artery (arrowheads) and the common bile duct. The cystic artery originates from the left hepatic artery (arrow) and reaches the gallbladder wall by coursing outside the Calot triangle (thin broken line). L = liver, PV = portal vein. (e) Composite drawing of a, c, and d shows the relationship between the cystic artery (arrowheads), which originates from the left hepatic artery (large arrow), and the Calot triangle. PHA = proper hepatic artery, RH = right hepatic artery.
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Figure 4c: Images show a type 1b relationship between the cystic artery and the Calot triangle in a 72-year-old woman. (a) Coronal black-and-white-reversed CT image obtained with a narrow window setting. In our routine clinical practice, this type of image is made for surgeons to depict the relationship between the cystic artery and the Calot triangle. In reality, CT image evaluation regarding the relationship between the cystic arteries, common bile duct (CBD), and cystic duct (CD) was performed with the paging method and abdominal window settings. GB = gallbladder. (b) Original window setting display image of a. (c, d) Thick-slab maximum intensity projection CT images show the relationship between the cystic artery (arrowheads) and the common bile duct. The cystic artery originates from the left hepatic artery (arrow) and reaches the gallbladder wall by coursing outside the Calot triangle (thin broken line). L = liver, PV = portal vein. (e) Composite drawing of a, c, and d shows the relationship between the cystic artery (arrowheads), which originates from the left hepatic artery (large arrow), and the Calot triangle. PHA = proper hepatic artery, RH = right hepatic artery.
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Figure 4d: Images show a type 1b relationship between the cystic artery and the Calot triangle in a 72-year-old woman. (a) Coronal black-and-white-reversed CT image obtained with a narrow window setting. In our routine clinical practice, this type of image is made for surgeons to depict the relationship between the cystic artery and the Calot triangle. In reality, CT image evaluation regarding the relationship between the cystic arteries, common bile duct (CBD), and cystic duct (CD) was performed with the paging method and abdominal window settings. GB = gallbladder. (b) Original window setting display image of a. (c, d) Thick-slab maximum intensity projection CT images show the relationship between the cystic artery (arrowheads) and the common bile duct. The cystic artery originates from the left hepatic artery (arrow) and reaches the gallbladder wall by coursing outside the Calot triangle (thin broken line). L = liver, PV = portal vein. (e) Composite drawing of a, c, and d shows the relationship between the cystic artery (arrowheads), which originates from the left hepatic artery (large arrow), and the Calot triangle. PHA = proper hepatic artery, RH = right hepatic artery.
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Figure 4e: Images show a type 1b relationship between the cystic artery and the Calot triangle in a 72-year-old woman. (a) Coronal black-and-white-reversed CT image obtained with a narrow window setting. In our routine clinical practice, this type of image is made for surgeons to depict the relationship between the cystic artery and the Calot triangle. In reality, CT image evaluation regarding the relationship between the cystic arteries, common bile duct (CBD), and cystic duct (CD) was performed with the paging method and abdominal window settings. GB = gallbladder. (b) Original window setting display image of a. (c, d) Thick-slab maximum intensity projection CT images show the relationship between the cystic artery (arrowheads) and the common bile duct. The cystic artery originates from the left hepatic artery (arrow) and reaches the gallbladder wall by coursing outside the Calot triangle (thin broken line). L = liver, PV = portal vein. (e) Composite drawing of a, c, and d shows the relationship between the cystic artery (arrowheads), which originates from the left hepatic artery (large arrow), and the Calot triangle. PHA = proper hepatic artery, RH = right hepatic artery.
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Comparison of CT Findings and Surgical Records
In the 48 patients in whom surgical observation was available at cholecystectomy (40 who underwent endoscopic surgery and eight who underwent open surgery), the cystic arteries were depicted in 44 patients (92%; 95% confidence interval: 87%, 98%) at CT. Two cystic arteries were found in 10 (23%) of the 44 patients; therefore, there were 54 cystic arteries in all, and all of them were confirmed at surgery. Every cystic artery identified preoperatively at CT was confirmed to be present at surgery, while any extra cystic artery that had been unidentified at CT was never found at surgery. Both the cystic duct and the cystic arteries were identifiable in 42 of 48 patients (88%; 95% confidence interval: 85%, 94%) (Figs 5, 6; Table 3). Such CT classification was confirmed to be in concert with the surgical findings in all 42 patients.
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Figure 5: Thick-slab maximum intensity projection CT image in a 36-year-old woman with abnormal arrangement of the pancreatobiliary ductal system shows the type 2a relationship between the two cystic arteries (small white arrows), the common bile duct (CBD), and the cystic duct (CD). Both cystic arteries originate from the right hepatic artery (large black arrow) and reach the gallbladder (GB) wall through the Calot triangle (thin broken line).
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Figure 6a: (a, b) Thick-slab maximum intensity projection CT images in a 55-year-old man with cholecystolithiasis show the type 2b relationship between the two cystic arteries, the common bile duct (CBD), and the cystic duct (CD). Both cystic arteries originate from the right hepatic artery (large arrow). In a, one cystic artery (arrowheads) originates from the right hepatic artery and reaches the gallbladder (GB) wall. In b, one cystic artery (white arrowheads) courses outside the Calot triangle (thin broken line), while the other cystic artery (black arrowhead) originates from the right hepatic artery and reaches the gallbladder wall. L = liver, PV = portal vein.
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Figure 6b: (a, b) Thick-slab maximum intensity projection CT images in a 55-year-old man with cholecystolithiasis show the type 2b relationship between the two cystic arteries, the common bile duct (CBD), and the cystic duct (CD). Both cystic arteries originate from the right hepatic artery (large arrow). In a, one cystic artery (arrowheads) originates from the right hepatic artery and reaches the gallbladder (GB) wall. In b, one cystic artery (white arrowheads) courses outside the Calot triangle (thin broken line), while the other cystic artery (black arrowhead) originates from the right hepatic artery and reaches the gallbladder wall. L = liver, PV = portal vein.
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DISCUSSION
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Our results showed that 64–detector row CT depicted structures that were consistent with the cystic artery in 96% of the patients (92% of patients who underwent cholecystectomy), and this result was superior to that obtained with four–detector row CT (25). To our knowledge, there has been only one article on depiction of the cystic artery with CT and MR imaging (25). Takahashi et al (25) stated that the cystic artery depiction rate was 90% with four–detector row CT. Although Takahashi et al (25) evaluated depiction of the celiac artery and the superior mesenteric artery, as well as the branches of these arteries, they did not address the course of the cystic artery regarding the relationship to the Calot triangle, since they focused on whether the cystic artery was visible.
It has been reported that the cystic arteries vary substantially (29), although the practice of obtaining detailed preoperative information about the arterial supply of the gallbladder seldom has been reported in the literature. Meanwhile, it has been reported that laparoscopic cholecystectomy was complicated by inadvertent injury to the cystic artery in 0.85% of patients (16). Injury to cystic arteries with an unexpected course during surgery and the resultant arterial bleeding could be particularly serious complications because too much suctioning would diminish the effect of pressure on the pneumoperitoneum that is applied to obtain a good laparoscopic visual field. In addition, such an effort to detect or coagulate a bleeding point in this situation may further increase the risk of injury to the arteries and bile ducts. Although it was not described how often such complications were associated with variations of the cystic arteries, we suspect their presence may increase the potential risk of accidental injury during laparoscopic cholecystectomy.
In some reports, authors have described the variations of cystic arteries in relation to the Calot triangle in intraoperative or autopsy cases (1–5,29). We adopted the classification of Suzuki et al (1) that was devised from a surgical standpoint and based on analysis of a large number of patients. The typical distribution of the cystic artery (ie, type 1a) was found in 78% of the patients. Important atypical features from a surgical standpoint may include a type 1b relationship with the cystic artery coursing outside the Calot triangle and type 2a and type 2b relationships with two cystic arteries (30). The frequency of these individual subtypes in all patients was similar to the frequency of the corresponding subtypes in the patients who underwent surgery, substantiating the classification regarding the relationship between the cystic artery and the Calot triangle that was obtained with 64–detector row CT in our study.
In our study, information on the anatomy of the biliary tree, including the cystic duct, was proved to be well provided by 64–detector row CT in most cases. Although cystic duct variations are not frequent occurrences, they may enhance the risk of bile duct injury. Biliary tract injury, which may occur owing to misidentification of the common bile duct as the cystic duct (7–12), can induce such a serious complication that the laparoscopic approach should be abandoned and open surgery should be chosen instead, as reported in 2%–7% of cases (8,16). The outcome after bile duct injury remains poor and leads to liver transplantation in the worst cases (10,11,14). Moreover, preoperative information on the cystic duct may be critical because it can be an important landmark with which to identify the cystic artery at cholecystectomy.
Information on the extrahepatic biliary tree is also obtained more clearly with drip-infusion cholangiography, CT cholangiography (17–20), or MR cholangiopancreatography than with 64–detector row CT performed without a biliary contrast agent. Unlike the data acquired with MR cholangiopancreatography or CT cholangiography, however, information on both the cystic arteries and the cystic duct can be obtained simultaneously with one 64–detector row CT examination, without use of a biliary contrast agent. This, in turn, enables us to evaluate the relationship between the cystic artery and the Calot triangle, which is crucial when surgery is performed. This is why we believe that 64–detector row CT has value in the preoperative evaluation before laparoscopic cholecystectomy.
When interpreting the results obtained in our study, some limitations must be considered. First, selection bias may have been introduced, as our subjects were selected from a group of patients suspected of having upper abdominal disease. Second, our study was retrospective. Third, the group that underwent surgery comprised a small number of patients, while our entire study comprised 245 patients.
In conclusion, 64–detector row CT can be used preoperatively to provide anatomic information on the cystic arteries and cystic duct simultaneously in patients who are to undergo cholecystectomy. For laparoscopic surgery, the information could potentially contribute to safer and more efficient procedures and enable inadvertent injuries to these structures to be avoided.
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ADVANCE IN KNOWLEDGE
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- Information on the cystic arteries and the cystic duct can be obtained simultaneously with one 64–detector row CT examination, without use of a biliary contrast agent.
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IMPLICATION FOR PATIENT CARE
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- Preoperative 64–detector row CT can provide anatomic information on the cystic arteries and the cystic duct simultaneously in patients who are to undergo cholecystec-tomy.
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ACKNOWLEDGMENTS
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We thank Ichiro Tsuji, PhD, MD, professor of the Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan, for statistical assistance with this manuscript.
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FOOTNOTES
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Author contributions: Guarantor of integrity of entire study, R.S.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, R.S.; clinical studies, R.S., T.Y., T.N.; statistical analysis, R.S.; and manuscript editing, R.S., N.F., M.K., S.T.
Authors stated no financial relationship to disclose.
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ABSTRACT
INTRODUCTION
