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Published online before print September 11, 2007, 10.1148/radiol.2451060951
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(Radiology 2007;245:483-490.)
© RSNA, 2007

Gastrointestinal Imaging

Malignant Intraductal Papillary Mucinous Neoplasm of the Pancreas: In Situ versus Invasive Carcinoma—Surgical Resectability1

Marie-Pierre Vullierme, MD, Marie Giraud-Cohen, MD, Pascal Hammel, MD, Alain Sauvanet, MD, Anne Couvelard, MD, Dermot O'Toole, MD, Philippe Levy, MD, Philippe Ruszniewski, MD, and Valérie Vilgrain, MD

1 From the Departments of Radiology (M.P.V., M.G., V.V.) and Pathology (A.C.) and the Fédération Médico Chirurgicale (P.H., A.S., D.O., P.L., P.R.), Beaujon Hospital, 100 boulevard général Leclerc, 92110 Clichy La Garenne, France. From the 2004 RSNA Annual Meeting. Received June 1, 2006; revision requested August 1; revision received October 2; accepted November 1; final version accepted March 7, 2007. Address correspondence to M.P.V. (e-mail: marie-pierre.vullierme{at}bjn.aphp.fr).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 
Purpose: To retrospectively evaluate computed tomographic (CT) findings in patients with in situ and invasive malignant intraductal papillary mucinous neoplasms (IPMNs) of the pancreas and to evaluate the accuracy for surgical resectability, with surgery and pathologic analysis as the reference standards.

Materials and Methods: Institutional review board approval was obtained, and the informed consent requirement was waived. Forty-six patients with malignant IPMN proved at pathologic examination of the surgically resected specimen (n = 44) or laparotomy (n = 2) underwent surgery after multidetector CT was performed. CT findings were retrospectively evaluated to determine if a pancreatic malignant IPMN tumor was present; to make this determination, CT criteria were used to differentiate in situ from invasive tumors and signs of unresectability (liver metastasis, vascular CT pattern of encasement, or regional lymph node metastasis). The extent of the vascular CT pattern of encasement was recorded for each patient (no obliteration of the fat plane, obliteration of the fat plane of <50%, or obliteration of the fat plane of ≥50%). Statistical analysis was performed with the {chi}2 and Student t tests.

Results: CT revealed a mural nodule in the pancreatic duct wall in 14 patients with in situ carcinoma and one patient with invasive carcinoma (P < .003). CT revealed an infiltrative pancreatic mass in 17 patients with invasive carcinoma and two patients with in situ carcinoma (P < .02). Of the mural nodules, 93% were seen in patients with in situ carcinoma, whereas 90% of infiltrative pancreatic masses were observed in patients with invasive carcinomas. The positive predictive value of CT for determining resectability was 100%, and the overall accuracy of CT for determining resectability and unresectability was 74%. The positive predictive value of CT for determining unresectability was 17%, mainly owing to overestimation of arterial invasion.

Conclusion: CT is helpful in the differentiation of in situ and invasive IPMN. Classic vascular invasion criteria lead to the overestimation of surgical tumor unresectability in patients with malignant IPMN.

© RSNA, 2007


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 
Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas originate from the mucinous epithelium of the pancreatic duct (main duct or branch ducts) and are characterized by papillary growth and variable amounts of mucinous secretion, which causes ductal dilatation (1–6). IPMNs may be classified as benign or malignant on the basis of the degree of dysplasia (2,7). Malignancy can occur in 30%–88% of patients as an in situ or invasive carcinoma (8). Study findings have shown that the prognosis of patients with malignant IPMN is similar to that of patients with pancreatic adenocarcinoma when there is invasion (9,10). Several reports have shown that there are distinct criteria with which to differentiate benign from malignant tumors (11–19); however, to our knowledge, no previous study has focused on the differentiation of in situ from invasive carcinoma. In situ carcinoma is clearly different from invasive carcinoma in pathologic examinations, and patients with these entities have different prognoses. In situ carcinoma is confined to the ductal structure and appears as an intraductal nodule or lesion surrounded by a sharp margin created by the ductal wall. Invasive carcinoma infiltrates the pancreatic parenchyma and appears as a poorly circumscribed infiltrated parenchymal lesion.

Surgical resection is the only curative treatment for malignant IPMN, and although magnetic resonance (MR) imaging and endoscopic ultrasonography help in the assessment of the resectability of malignant IPMN, computed tomography (CT) remains the mainstay in the evaluation of these patients (12,20–25). Although inflammation and mucus secretion may make evaluation of vascular encasement difficult, to our knowledge, there are no reports on the accuracy of CT in the evaluation of the resectability of malignant IPMNs. Although CT criteria that were established in patients with pancreatic adenocarcinoma are currently used to evaluate malignant IPMN (26–31), the value of these criteria in assessing the surgical resectability of IPMNs has not been determined (32–35). Thus, our strategy was to perform surgery in all patients without metastases to give them the opportunity for curative treatment.

Our goals were to retrospectively evaluate CT findings in patients with in situ and invasive malignant IPMN and to evaluate the accuracy for surgical resectability, with surgery and pathologic analysis as the reference standards.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 
Patients and Tumor Categorization
This study was approved by our institutional review board. The informed consent requirement was waived. Over an 11-year period, 52 of 150 consecutive patients with IPMN who received care at our institution had tumors that were proved malignant at surgery (Fig 1). An additional 13 patients did not undergo surgery because of obvious metastatic spread seen on CT images (n = 4) (two patients with hypoattenuated nodules without cystic component and two with pulmonary lymphangitic carcinomatosis), nodular peritoneal carcinomatosis (n = 3) or ascites (n = 4), or age older than 75 years and associated diseases (n = 2). It is our policy to not perform surgery in patients with IPMN who have ascites because of the strong likelihood of malignancy and the high risk of postoperative complications.


Figure 1
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  		Figure 1: Flow diagram of included patients. MDCT = multidetector CT.

 
Six of the 52 patients with malignant IPMN who underwent surgery were excluded because of the CT technique that was used (conventional CT in five patients and unenhanced CT only in one). Thus, our study included 46 patients (27 men, 19 women; age range, 43–78 years; mean age, 61 years) with proved malignant IPMN who underwent surgery and multiphasic multidetector CT. Forty-four patients underwent pancreatectomy, and two underwent laparotomy without tumor resection.

Malignant IPMN was categorized as in situ or invasive carcinoma according to the World Health Organization classification (2). In situ carcinoma (or high-grade ductal dysplasia) was characterized by a ductal epithelium with irregular projections lacking fibrovascular stalks. The nuclei showed marked abnormalities, and nuclear polarity was lost. No malignant nodal invasion was present. Invasive carcinoma was defined as the presence of individual infiltrating cells or malignant infiltrative glands with an accompanying desmoplastic stromal reaction (2,4,6).

CT Technique
Multiphasic helical CT was performed with two consecutive CT machines. The first CT scanner (CT Twin; Marconi, Haifa, Israel) was used to examine 27 patients. Unenhanced CT (5-mm section thickness) was followed by contrast material–enhanced CT performed during the (a) late arterial phase, referred to as the pancreatic phase (2.5-mm section thickness, 1.5 pitch), and (b) portal venous phase (5.0-mm section thickness, 1.5 pitch), with delays of 45 and 70 seconds, respectively, after initiation of an intravenous bolus injection of 100–120 mL of low-osmolality contrast material (iohexol [350 mg of iodine per milliliter], Omnipaque, Nycomed Amersham, Princeton, NJ; or iobitridol [350 mg/mL], Xenetix, Guerbet, Aulnay-sous-bois, France) at a flow rate of 3 mL/sec. Water was ingested. Nine CT examinations were performed before 1996, and the arterial phase was started 30 seconds after intravenous contrast material was injected.

The second CT scanner (CT Light Speed Ultra; GE Healthcare, Milwaukee, Wis) was used to examine 19 patients. Images were acquired with 1.25-mm section thickness. Reconstruction during the unenhanced (5.0-mm section thickness, 1.35 pitch), pancreatic (2.5-mm section thickness, 0.875 pitch), and portal venous (5.0-mm section thickness, 0.875 pitch) phases was performed with delays of 45 and 70 seconds for pancreatic and portal venous phases, respectively, after initiation of an intravenous bolus injection of 100–120 mL of low-osmolality iodine-based contrast material administered with a 3 mL/sec flow rate. Water was ingested.

Image Analysis
Images obtained during the different phases were evaluated together on film hard copies. All images were interpreted retrospectively and jointly in consensus by two abdominal radiologists (M.P.V. and M.G., with 20 and 10 years of experience, respectively) who were aware of the diagnosis of malignant IPMN but were unaware of the surgical and histopathologic results.

IPMN was classified as main duct type, branch duct type, or mixed type with the classification system described by Kobari et al (36). IPMN location (head, body, tail, or body and tail), maximum diameter of the main pancreatic duct (MPD), and maximum size of the enlarged branch ducts were recorded (20,21). Presence of calcifications was noted.

CT criteria evaluated for use in the differentiation of in situ and invasive tumors were as follows: (a) stenosis of the MPD; (b) intraductal mural nodule, defined at CT as a solid nodule in the MPD or a branch duct or as a well-circumscribed tissue lesion surrounded by a duct wall; and (c) infiltrative tumor, defined at CT as a solid lesion with attenuation that was different from that of the adjacent pancreatic parenchyma and that infiltrated the parenchyma and mimicked pancreatic carcinoma (12,15,16,22). The readers (M.P.V., M.G.) gave their opinion as to whether these findings could be used to differentiate invasive from in situ carcinoma. Their opinion was compared with the reference standard (pathologic analysis).

Tumor extension and resectability were evaluated with CT criteria for pancreatic adenocarcinoma (26,28–30). Tumor spread (defined later) to vascular structures and adjacent organs (duodenum, bile ducts) was evaluated. The arterial CT pattern of encasement was defined as obliteration of the fat plane of less than 50% or obliteration of at least 50% for the celiac trunk and the hepatic and superior mesenteric arteries. Venous CT pattern of encasement was defined as complete circumferential obliteration of the fat plane of 50% or more, deformation of the superior mesenteric vein into the tear drop sign, or thrombosis or obliteration of the lumen (29,31). Obliteration of the fat plane of less than 50% was not considered venous encasement (28).

The presence of abnormal peripancreatic fat (defined as the presence of visually perceptible increased attenuation compared with the attenuation of abdominal fat) was assessed (31). The presence of peripancreatic or distant lymph nodes was also assessed. Metastatic adenopathy was diagnosed if the small axis of a node was larger than 10 mm or if nodes were round or had a necrotic center (37).

Patients were suspected of having duodenopancreatic fistula if CT revealed an enlarged duodenal lumen with rupture of the duodenal wall. Biliary abnormalities were defined as marked enhancement of the biliary wall on postcontrast CT images, biliary dilatation, or direct communication between the pancreatic and bile ducts, with disappearance of the bile duct wall and pancreatic duct wall.

Surgical resection criteria were as follows: A lesion was considered unresectable when the arterial CT pattern of encasement was greater than 50%. The venous CT pattern of encasement as described previously without thrombosis or obliteration of the lumen was not considered unresectable, and the surgeon was prepared for venous resection.

Surgical Procedures
The delay between CT scanning and surgery ranged from 1 to 40 days (mean delay, 28 days). Pancreatic resections were performed in 44 patients as follows: Duodenopancreatectomy was performed in 23 patients; extended duodenopancreatectomy, in eight patients; extended left pancreatectomy, in seven patients; and total pancreatectomy, in six patients. Pancreatic resection was guided by intraoperative frozen section examination in all patients (6,38). In two patients, laparotomy was not followed by resection because vascular invasion made surgical resection impossible.

Histopathologic Data and Comparisons
All malignant IPMNs were proved either at pathologic examination of the surgically resected specimen (n = 44) or at laparotomy (n = 2). The following features were analyzed by a gastrointestinal pathologist with 10 years of experience (A.C.): characteristics of IPMN (type, location, diameter of the MPD, and size of the branch duct lesions), location and size of the malignant portion, abundance of the mucinous secretion, tumor extension into peripancreatic tissue (peripancreatic fat, vascular involvement, and perineural invasion), and distant structures (lymph node involvement and metastases). Presence of biliary or digestive fistulas (ulceration of the biliary or digestive wall with mucinous material filling the biliary or digestive lumen) was evaluated. CT findings were compared with surgical and pathologic findings (M.P.V., M.G.) in the 44 patients who underwent surgery and with surgical reports in the two patients who underwent only laparotomy.

Statistical Analysis
Statistical analysis was performed with the {chi}2 test for percentages and the Student t test for mean values. Statistical software was used to perform both tests (StatView-J 5.0; SAS Institute, Cary, NC). For both tests, significance was set at a P value of less than .05.

Overall accuracy was defined as the proportion of accurate CT diagnoses compared with surgical and pathologic findings (n = 46). The accuracy of CT in determining resectability or unresectability and the positive predictive value of CT for determining resectability and unresectability were calculated.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 
CT Patterns for in Situ and Invasive Carcinoma
The main pancreatic duct was dilated more than 10 mm in 38 (83%) of 46 patients (mean diameter, 14.3 mm) and was not different between patients with in situ and those with invasive carcinoma (Table 1). Stenosis of the main pancreatic duct was not observed. The mean size of enlarged branch duct lesions was 19.5 mm (range, 2–80 mm), including five branch ducts larger than 30 mm, and was not different between patients with in situ and those with invasive carcinoma.


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  		Table 1. CT Findings in Patients with Malignant IPMN

 
CT revealed a mural nodule in 14 (56%) of 25 patients with in situ carcinoma (Figs 2, 3) and in one (5%) of 21 patients with invasive carcinoma (P < .003). CT revealed an infiltrative pancreatic mass (Figs 4–6) in 17 (81%) of 21 patients with invasive carcinoma (Figs 4, 5) and in two (8%) of 25 patients with in situ carcinoma (P < .02). We observed 14 (93%) of the 15 mural nodules in patients with in situ carcinomas, whereas 17 (90%) of the 19 infiltrative pancreatic masses were observed in patients with invasive carcinomas.


Figure 2
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  		Figure 2: Transverse arterial phase postcontrast CT image in a 73-year-old woman with mixed IPMN shows in situ carcinoma in the MPD of the body. The intraductal mural nodule (arrow) extends into the MPD of the body. The MPD is enlarged (15 mm), and there is no vascular encasement. Splenopancreatectomy extended to the right.

 

Figure 3
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  		Figure 3: Transverse venous phase postcontrast CT image in a 58-year-old man with mixed IPMN shows overstaging of in situ carcinoma in the MPD of the tail. The intraductal mural nodule (arrow) extends into the MPD of the tail. MPD is enlarged (20 mm) downstream. Note obliteration of the fat plane of more than 50% for the celiac trunk and the hepatic artery (arrowhead). This patient was considered unsuitable for resection because of a CT aspect of malignant encasement; however, he underwent resection and total pancreatectomy.

 

Figure 4
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  		Figure 4: Transverse venous phase postcontrast CT image in a 51-year-old woman with mixed IPMN shows invasive malignant IPMN of a branch duct. Note the solid lesion with attenuation that is different from that of the adjacent pancreatic parenchyma and is infiltrating the parenchyma. The lesion (arrows) in the head of the pancreas is not well circumscribed and hypoattenuating. Branch ducts are enlarged in the uncinate process (white arrowhead). MPD (black arrowhead) is also enlarged (13 mm). The Whipple procedure was performed.

 

Figure 5
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  		Figure 5: Transverse venous phase postcontrast CT image in a 47-year-old man with mixed IPMN shows invasive malignant IPMN in the MPD. Note the solid lesion with attenuation that is different from that of the adjacent pancreatic parenchyma of the head and infiltrating the parenchyma (arrowhead). Calcification (arrow) is also visible. No vascular encasement was seen. The Whipple procedure was performed.

 

Figure 6
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  		Figure 6: Transverse arterial phase postcontrast CT scan in a 67-year-old woman with mixed IPMN shows overstaging of an invasive malignant IPMN in the MPD. Note the solid lesion with attenuation that is different from that of the adjacent pancreatic parenchyma of the tail and infiltrating the parenchyma (straight arrow). A dilated distal pancreatic branch duct (bent arrow) can also be seen. Note the obliteration of the fat plane of less than 50% of the right side of the mesenteric artery (arrowhead). This patient was considered unsuitable for resection because of a CT aspect of malignant encasement; however, she underwent resection and total pancreatectomy.

 
Twelve (26%) lesions, including three invasive lesions, were not identified on CT images. The invasive lesions were infiltrative lesions that involved the entire head of the pancreas. The nine remaining lesions were in situ carcinomas smaller than 1 mm at pathologic analysis. In patients with lesions that were not identified at CT, the size of the main pancreatic duct was normal (n = 3) or enlarged (n = 9; mean size, 16 mm; five ducts > 15 mm). The mean size of the largest pancreatic branch duct was 23.5 mm (range, 5–80 mm). Calcifications were present in four of the 12 patients.

Metastatic lesions and peritoneal involvement were never discovered at surgery. Abnormal peripancreatic lymph node involvement was present in 25% of patients, including 58% of patients with invasive tumors. CT findings indicative of digestive fistula were seen in five (11%) of 46 patients with in situ (n = 2) or invasive (n = 3) carcinomas. Pancreaticobiliary fistulas were not observed. Dilatation of the main bile duct was found on CT images in seven patients with invasive carcinomas (n = 6) or in situ lesions (n = 1).

Accuracy of CT Criteria for Surgical Resectability
The overall accuracy of helical CT in determining surgical resectability of malignant IPMNs with adenocarcinoma criteria was 74% (Table 2). The positive predictive value of helical CT with use of adenocarcinoma criteria in determining whether malignant IPMNs were resectable was 100%. The positive predictive value of helical CT in determining whether malignant IPMNs were nonresectable was 17% (Figs 3, 6).


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  		Table 2. Surgical Resectability according to CT Results in 46 Patients with Malignant IPMN

 
Among the 23 patients with abnormal peripancreatic soft tissue, 17 had a history of acute pancreatitis. Ten of 12 patients with arterial CT patterns of encasement of more than 50% had a marked perivascular inflammatory reaction at pathologic analysis and no tumor surrounding the vessels. This pattern was observed in patients with invasive carcinoma and in those with in situ carcinoma. No relationship between abundance of tumoral mucinous secretions and abnormal peripancreatic soft tissue was found.


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 
To our knowledge, no prior published study has been performed to evaluate the role of CT in distinguishing in situ from invasive IPMN. It is interesting to note that in our study 14 (93%) of 15 mural nodules were associated with in situ IPMN, whereas 17 (90%) of 19 infiltrative masses were associated with invasive carcinoma. The presence of mural nodules has been reported in 18.5%–50% of patients with IPMN; however, to our knowledge, the relationship between mural nodules and the pathologic type of malignant IPMN has not been investigated (22,23). In our study, 12 patients did not have mural nodules or pancreatic solid masses, but they did have isolated dilatation of the main pancreatic duct or branch ducts. Only three of these patients had invasive IPMN. In our study, there was no pancreatic mass at CT in three (14%) of the 21 patients with invasive IPMN. This suggests that when multidetector CT reveals a pancreatic solid mass in patients with IPMN, the lesion is probably invasive carcinoma. In contrast to pancreatic adenocarcinoma, stenosis of the main pancreatic duct was not observed in these patients. Our results confirm the findings of a recent study in which invasive carcinoma was shown to have a more solid appearance than in situ carcinoma or benign IPMNs (18). Moreover, we have demonstrated that the presence of mural nodules is highly suggestive of in situ carcinoma, and unlike Kawamoto et al (18), we think that in situ carcinoma could be prospectively detected because CT depicted mural nodules in more than half of the patients in our study. The other findings of our study were that diameter of branch ducts and location and presence of calcifications did not differ between patients with in situ carcinoma and those with invasive carcinoma. All of our results are in agreement with the findings of Kawamoto et al (18), with the exception of the caliber of MPD, which was significantly larger in their series of invasive carcinoma compared with lesions without invasive carcinomas. However, Kawamoto et al included benign IPMNs and in situ lesions in the latter group. We also observed substantial dilatation of the main bile duct in association with invasive carcinomas.

Moreover, our findings enabled us to confirm that malignant IPMN is mainly observed in patients with main duct type or mixed type IPMN (4,36). Only five patients (11%) had branch duct type IPMN, but most of the neoplasms were invasive carcinomas. During the same period, 29 patients with benign branch duct IPMNs and 14 patients with mixed type IPMNs underwent surgery at our institution (Beaujon Hospital, unpublished data, 1996–2004).

Increased attenuation of peripancreatic fat was a frequent finding in our series, occurring in 23 (50%) of 46 patients. This was related to inflammatory changes in all patients and was secondary to acute pancreatitis in most of them. Pancreatitis is more common in patients with IPMN (ie, 30% of patients) than in patients with pancreatic adenocarcinoma (ie, 3% of patients) (39). This fat infiltration should not be a contraindication to surgery. The vascular CT pattern of encasement is an important criterion in the evaluation of tumor resectability in patients with pancreatic adenocarcinomas, and the arterial CT pattern of encasement has been associated with 84% of unresectable cases (28). However, Nakayama et al (39) found that 40% of pancreatic cancers (IPMN excluded) with this feature were still resectable at surgery because the arterial abnormalities on CT images may have corresponded to inflammatory reactions or atheromatous stenosis. Coley et al (40) emphasized that care should be taken when interpreting the vascular CT pattern of encasement if only one artery is encased. They believe that resection can be undertaken unless several arteries are involved. However, the idea that resection of adenocarcinoma of the pancreas should be attempted unless several arteries are encased is not the majority opinion and is highly controversial.

Our series results show that vascular criteria are less accurate in the evaluation of IPMN resectability than in the evaluation of pancreatic carcinoma. Ten of 12 patients with a CT pattern of encasement of more than 50% of the celiac trunk or mesenteric artery underwent resection. Even with involvement of multiple arteries, four of five patients underwent surgical resection.

Lymph node involvement was present in 25% of patients in our study, including 58% of those with invasive tumors. In the study by Maire et al (10), only 33% of metastatic nodes were found in patients with invasive tumors. Lymph node involvement occurs less frequently in patients with IPMN than in those with adenocarcinoma (76%). In the study by Roche et al (37), CT depiction of peripancreatic nodes had poor sensitivity and specificity for the diagnosis of pancreatic adenocarcinoma; thus, it should not prevent curative resection. Metastatic lesions and peritoneal involvement, unlike pancreatic adenocarcinoma, were never discovered at surgery. Extension of IPMN to the digestive tracts occurred rarely and only in benign or malignant IPMNs. Obvious digestive tract fistula is not always associated with invasive carcinomas, and it could be associated with in situ carcinomas (40% of our series); therefore, surgical resection should not be contraindicated (18,20).

The positive predictive value of helical CT as a tool with which to determine if a malignant IPMN was not resectable was 17% (two of 12 patients). This indicates that evaluation with CT tends to result in overestimation of nonresectability in patients with malignant IPMN, mainly because vascular encasement is overestimated. Meanwhile, surgical management is the only curative treatment at present. However, when arterial encasement of more than 50% is seen at CT, the presence of an infiltrative mass increases the probability of nonresectability.

Our study had several limitations. We used the CT criteria of vascular encasement that are currently used in the literature; however, some authors have suggested tumor-to-vessel contiguity is more specific in patients with adenocarcinoma (31). The venous CT pattern of encasement without thrombosis or obliteration of the lumen was not considered unresectable, as this criterion is no longer used by surgeons at our institution. However, some surgeons consider these conditions contraindications to resection.

Two consecutive helical CT machines were used between the beginning and the end of patient enrollment. Thus, our population might have lacked homogeneity. Although these technical differences may have changed the results, we did not attempt to analyze both subject groups separately. Furthermore, the main pitfall regarding resectability is overestimation, not underestimation. Although use of the more modern CT techniques increases sensitivity in the detection of arterial invasion, it probably does not increase specificity.

Some CT signs, especially the presence and degree of vascular encasement, are somewhat subjective; therefore, they could be less reliable. As we did not attempt to evaluate the interobserver variability, this cannot be demonstrated. Only film hard-copy transverse CT images were reviewed. Multiplanar reformation was not performed systematically. This could have limited the accuracy of CT, as has been the case in patients with ductal adenocarcinoma. However, to our knowledge, the role of multiplanar reformation has not been evaluated in patients with IPMN.

Another limitation was related to nonoptimized multidetector CT with venous phase using 5-mm images combined with hard-copy image review. This limitation could limit the accuracy of CT in the depiction of ductal nodularity. Another limitation concerned the fact that given more data, covariate analysis may be needed to ascertain confounding variables.

In conclusion, malignant IPMNs often appear as intraductal nodules or pancreatic masses on CT images. The appearance of the tumor on CT images seems to reflect the histopathologic findings, since most pancreatic masses were associated with invasive carcinomas and most intraductal nodules corresponded to in situ carcinomas. In patients with malignant IPMN, the classic criteria used to evaluate vascular invasion resulted in overestimation of surgical unresectability.


   ADVANCES IN KNOWLEDGE
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
IMPLICATION FOR PATIENT CARE
 References
 


   IMPLICATION FOR PATIENT CARE
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
References
 


   FOOTNOTES
 

Abbreviations: IPMN = intraductal papillary mucinous neoplasm • MPD = main pancreatic duct

Guarantors of integrity of entire study, M.P.V., M.G., A.S., A.C., P.R., V.V.; 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, M.P.V., M.G., A.S., A.C., P.L., P.R., V.V.; clinical studies, all authors; statistical analysis, M.P.V., M.G., D.O., P.R., V.V.; and manuscript editing, M.P.V., M.G., A.C., P.R., V.V.

Authors stated no financial relationship to disclose.


   References
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 

  1. Cubilla AL, Fitzgerald PJ. Tumors of the exocrine pancreas. Fascicle 19, 2nd series. Washington, DC: Armed Forces Institute of Pathology, 1984.
  2. Longnecker DS, Adler G, Hruban RH, et al. Intraductal papillary-mucinous neoplasms of the pancreas. In: WHO classification of tumors of the digestive system. Lyon, France: IARC, 2000; 237–240.
  3. Kloppel G, Solcia E, Longnecker DS, Capella C, Sobin LH. Histological typing of tumors of the exocrine pancreas. In: WHO international histological classification of tumours. Berlin, Germany: Springer, 1996.
  4. Terris B, Ponsot P, Paye F, et al. Intraductal papillary mucinous tumors of the pancreas confined to secondary ducts show less aggressive pathologic features as compared with those involving the main pancreatic duct. Am J Surg Pathol 2000;24:1372–1377. [Medline]
  5. Bernard P, Scoazec JY, Joubert M, et al. Intraductal papillary-mucinous tumors of the pancreas: predictive criteria of malignancy according to pathological examination of 53 cases. Arch Surg 2002;137:1274–1278. [Abstract/Free Full Text]
  6. Couvelard A, Sauvanet A, Kianmanesh R, et al. Frozen sectioning of the pancreatic cut surface during resection of intraductal papillary mucinous neoplasms of the pancreas is useful and reliable: a prospective evaluation. Ann Surg 2005;242:774–778. [CrossRef][Medline]
  7. Hruban RH, Takaori K, Klimstra DS, et al. An illustrated consensus on the classification of pancreatic intraepithelial neoplasia and intraductal papillary mucinous neoplasms. Am J Surg Pathol 2004;28:977–987. [Medline]
  8. Raimondo M, Tachibana I, Urrutia R, Burgart LJ, DiMagno EP. Invasive cancer and survival of intraductal papillary mucinous tumors of the pancreas. Am J Gastroenterol 2002;97:2553–2558. [CrossRef][Medline]
  9. Sohn TA, Yeo CJ, Cameron JL, et al. Intraductal papillary mucinous neoplasms of the pancreas: an updated experience. Ann Surg 2004;239:788–797. [CrossRef][Medline]
  10. Maire F, Hammel P, Terris B, et al. Prognosis of malignant intraductal papillary mucinous tumours of the pancreas after surgical resection: comparison with pancreatic ductal adenocarcinoma. Gut 2002;51:717–722. [Abstract/Free Full Text]
  11. Kimura W, Sasahira N, Yoshikawa T, Muto T, Makuuchi M. Duct-ectatic type of mucin producing tumor of the pancreas: new concept of pancreatic neoplasia. Hepatogastroenterology 1996;43:692–709. [Medline]
  12. Yamaguchi K, Ogawa Y, Chijiiwa K, Tanaka M. Mucin-hypersecreting tumors of the pancreas: assessing the grade of malignancy preoperatively. Am J Surg 1996;171:427–431. [CrossRef][Medline]
  13. Sugiyama M, Atomi Y, Kuroda A. Two types of mucin-producing cystic tumors of the pancreas: diagnosis and treatment. Surgery 1997;122:617–625. [CrossRef][Medline]
  14. Sugiyama M, Atomi Y. Intraductal papillary mucinous tumors of the pancreas: imaging studies and treatment strategies. Ann Surg 1998;228:685–691. [CrossRef][Medline]
  15. Sugiyama M, Izumisato Y, Abe N, Masaki T, Mori T, Atomi Y. Predictive factors for malignancy in intraductal papillary-mucinous tumours of the pancreas. Br J Surg 2003;90:1244–1249. [CrossRef][Medline]
  16. Taouli B, Vilgrain V, Vullierme MP, et al. Intraductal papillary mucinous tumors of the pancreas: helical CT with histopathologic correlation. Radiology 2000;217:757–764. [Abstract/Free Full Text]
  17. Taouli B, Vilgrain V, O'Toole D, Vullierme MP, Terris B, Menu Y. Intraductal papillary mucinous tumors of the pancreas: features with multimodality imaging. J Comput Assist Tomogr 2002;26:223–231. [CrossRef][Medline]
  18. Kawamoto S, Lawler LP, Horton KM, Eng J, Hruban RH, Fishman EK. MDCT of intraductal papillary mucinous neoplasm of the pancreas: evaluation of features predictive of invasive carcinoma. AJR Am J Roentgenol 2006;186:687–695. [Abstract/Free Full Text]
  19. Pilleul F, Rochette A, Partensky C, Scoazec JY, Bernard P, Valette PJ. Preoperative evaluation of intraductal papillary mucinous tumors performed by pancreatic magnetic resonance imaging and correlated with surgical and histopathologic findings. J Magn Reson Imaging 2005;21:237–244. [CrossRef][Medline]
  20. Procacci C, Graziani R, Bicego E, et al. Intraductal mucin-producing tumors of the pancreas: imaging findings. Radiology 1996;198:249–257. [Abstract/Free Full Text]
  21. Procacci C, Carbognin G, Biasiutti C, Guarise A, Ghirardi C, Schenal G. Intraductal papillary mucinous tumors of the pancreas: spectrum of CT and MR findings with pathologic correlation. Eur Radiol 2001;11:1939–1951. [CrossRef][Medline]
  22. Fukukura Y, Fujiyoshi F, Sasaki M, Inoue H, Yonezawa S, Nakajo M. Intraductal papillary mucinous tumors of the pancreas: thin-section helical CT findings. AJR Am J Roentgenol 2000;174:441–447. [Abstract/Free Full Text]
  23. Irie H, Honda H, Aibe H, et al. MR cholangiopancreatographic differentiation of benign and malignant intraductal mucin-producing tumors of the pancreas. AJR Am J Roentgenol 2000;174:1403–1408. [Abstract/Free Full Text]
  24. Yamao K, Ohashi K, Nakamura T, et al. Evaluation of various imaging methods in the differential diagnosis of intraductal papillary-mucinous tumor (IPMN) of the pancreas. Hepatogastroenterology 2001;48:962–966. [Medline]
  25. Aithal GP, Chen RY, Cunningham JT, et al. Accuracy of EUS for detection of intraductal papillary mucinous tumor of the pancreas. Gastrointest Endosc 2002;56:701–707. [CrossRef][Medline]
  26. Diehl SJ, Lehmann KJ, Sadick M, Lachmann R, Georgi M. Pancreatic cancer: value of dual-phase helical CT in assessing resectability. Radiology 1998;206:373–378. [Abstract/Free Full Text]
  27. Bluemke DA, Cameron JL, Hruban RH, et al. Potentially resectable pancreatic adenocarcinoma: spiral CT assessment with surgical and pathologic correlation. Radiology 1995;197:381–385. [Abstract/Free Full Text]
  28. Lu DS, Reber HA, Krasny RM, Kadell BM, Sayre J. Local staging of pancreatic cancer: criteria for unresectability of major vessels as revealed by pancreatic-phase, thin-section helical CT. AJR Am J Roentgenol 1997;168:1439–1443. [Abstract/Free Full Text]
  29. Hough TJ, Raptopoulos V, Siewert B, Matthews JB. Teardrop superior mesenteric vein: CT sign for unresectable carcinoma of the pancreas. AJR Am J Roentgenol 1999;173:1509–1512. [Abstract]
  30. O'Malley ME, Boland GW, Wood BJ, Fernandez-del Castillo C, Warshaw AL, Mueller PR. Adenocarcinoma of the head of the pancreas: determination of surgical unresectability with thin-section pancreatic-phase helical CT. AJR Am J Roentgenol 1999;173:1513–1518.
  31. Valls C, Andia E, Sanchez A, et al. Dual-phase helical CT of pancreatic adenocarcinoma: assessment of resectability before surgery. AJR Am J Roentgenol 2002;178:821–826. [Abstract/Free Full Text]
  32. Traverso LW. Surgical treatment of intraductal papillary mucinous neoplasms of the pancreas: the aggressive approach. J Gastrointest Surg 2002;6:662–663. [CrossRef][Medline]
  33. Doi R, Fujimoto K, Wada M, Imamura M. Surgical management of intraductal papillary mucinous tumor of the pancreas. Surgery 2002;132:80–85. [CrossRef][Medline]
  34. Loftus EV Jr, Olivares-Pakzad BA, Batts KP, et al; and the Members of the Pancreas Clinic, and Pancreatic Surgeons of Mayo Clinic. Intraductal papillary-mucinous tumors of the pancreas: clinicopathologic features, outcome, and nomenclature. Gastroenterology 1996;110:1909–1918.
  35. Matsumoto T, Aramaki M, Yada K, et al. Optimal management of the branch duct type intraductal papillary mucinous neoplasms of the pancreas. J Clin Gastroenterol 2003;36:261–265. [CrossRef][Medline]
  36. Kobari M, Egawa S, Shibuya K, et al. Intraductal papillary mucinous tumors of the pancreas comprise 2 clinical subtypes: differences in clinical characteristics and surgical management. Arch Surg 1999;134:1131–1136. [Abstract/Free Full Text]
  37. Roche CJ, Hughes ML, Garvey CJ, et al. CT and pathologic assessment of prospective nodal staging in patients with ductal adenocarcinoma of the head of the pancreas. AJR Am J Roentgenol 2003;180:475–480. [Abstract/Free Full Text]
  38. Paye F, Sauvanet A, Terris B, et al. Intraductal papillary mucinous tumors of the pancreas: pancreatic resections guided by preoperative morphological assessment and intraoperative frozen section examination. Surgery 2000;127:536–544. [CrossRef][Medline]
  39. Nakayama Y, Yamashita Y, Kadota M, et al. Vascular encasement by pancreatic cancer: correlation of CT findings with surgical and pathologic results. J Comput Assist Tomogr 2001;25:337–342. [CrossRef][Medline]
  40. Coley SC, Strickland NH, Walker JD, Williamson RC. Spiral CT and the pre-operative assessment of pancreatic adenocarcinoma. Clin Radiol 1997;52:24–30. [CrossRef][Medline]



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H. Ogawa, S. Itoh, M. Ikeda, K. Suzuki, and S. Naganawa
Intraductal Papillary Mucinous Neoplasm of the Pancreas: Assessment of the Likelihood of Invasiveness with Multisection CT
Radiology, September 1, 2008; 248(3): 876 - 886.
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