Diagnostic Value of Multislice Computed Tomography for Pancreas Divisum

Congenital pancreatic anomalies, variants, and conditions

Understanding pancreatic development and the congenital anomalies and variants that result from alterations in normal development allows for better recognition of these anomalies at diagnostic imaging. This article reviews normal pancreatic embryology and anatomy, and the appearance of the more common developmental anomalies and ductal variants, with emphasis on computed tomography and magnetic resonance imaging. Common mimics of masses are also covered.

Detectability of pancreas divisum in patients with acute pancreatitis on multi-detector row computed tomography

The purpose of this study was to retrospectively assess the diagnostic performance of multi-detector row computed tomography (MDCT) in an evaluation of pancreas divisum using endoscopic retrograde pancreatography (ERP) as the reference standard. We analyzed 41 consecutive patients (14 cases of pancreas divisum and 27 cases of standard anatomy) who had undergone both MDCT and ERP for the evaluation of clinically diagnosed acute pancreatitis between November 2004 and June 2007. The CT reconstruction thickness and interval were both 3 mm. Two radiologists independently reviewed CT data, and the diagnostic confidence in determining the pancreatic ductal anatomy was scored using a five-point scale. CT detectability was correlated with the severity of pancreatitis and the degree of pancreatic necrosis based on the Balthazar index. With consensus, 16 of 41 cases (39.0%) were evaluated as indeterminate. Ductal anatomy was correctly diagnosed in 23 of 41 cases (56.1%). Eight of 14 cases (57.1%) were correctly diagnosed as pancreas divisum. Standard anatomy was identified in 15 of 27 cases (55.6%). The inter-observer agreement was substantial (κ = 0.71). Grade B or more pancreatitis and the presence of pancreatic necrosis significantly influenced the evaluation of ductal anatomy (p = 0.01 and p < 0.01, respectively). Pancreas divisum was correctly diagnosed in the case of grade A acute pancreatitis. The CT detectability of pancreas divisum in patients with grade B or more pancreatitis is still relatively low even in the MDCT era.

Post-gastrectomy acute pancreatitis in a patient with gastric carcinoma and pancreas divisum

Gastrectomy is commonly performed for both benign and malignant lesions. Although the incidence of post-gastrectomy acute pancreatitis (PGAP) is low compared to other well-recognized post-operative complications, it has been reported to be associated with a high mortality rate. In this article, we describe a 70-year-old man with asymptomatic pancreatic divisum who underwent palliative subtotal gastrectomy for an advanced gastric cancer with liver metastasis. His post-operative course was complicated by acute pancreatitis and intra-abdominal sepsis. The patient eventually succumbed to multiple organ failure despite surgical debridement and drainage, together with aggressive antibiotic therapy and nutritional support. For patients with pancreas divisum or dominant duct of Santorini who fail to follow the normal post-operative course after gastrectomy, clinicians should be alert to the possibility of PGAP as one of the potential diagnoses. Early detection and aggressive treatment of PGAP might improve the prognosis.

[Pancreas. Congenital changes, acute and chronic pancreatitis]

The pancreas develops from ventral and dorsal buds, which undergo fusion. Failure to fuse results in pancreas divisum, which is defined by separate pancreatic ductal systems draining into the duodenum. Risk of developing pancreatitis is increased in pancreas divisum. MR cholangiopancreatography (MRCP) is the technique of choice for detecting it non-invasively. Annular pancreas is the result of incomplete rotation of the pancreatic bud around the duodenum with the persistence of parenchyma or a fibrous band encircling (stenosing) the duodenum. Acute pancreatitis is usually caused by bile duct stones or alcohol abuse. Contrast-enhanced multi-detector row CT is the method of choice to assess the extent of this disease. In acute pancreatitis, the role of MRCP is mainly limited to finding bile duct stones in patients with suspected biliary pancreatitis. Chronic pancreatitis results in relentless and irreversible loss of exocrine (and sometimes endocrine) function of the pancreas. MDCT even shows subtle calcifications. MRCP is the method of choice for non-invasive assessment of the duct. Inflammatory pseudotumor in chronic pancreatitis and groove pancreatitis are difficult to differentiate from pancreatic cancer. In these cases, multiple imaging methods such as MDCT, MRI and endosonography including biopsy may be used to make a diagnosis.

Intraductal papillary mucinous neoplasm of the pancreas: assessment of the likelihood of invasiveness with multisection CT

PURPOSE

To evaluate the capabilities of multisection computed tomography (CT) in determining the likelihood of invasiveness of intraductal papillary mucinous neoplasm (IPMN).

MATERIALS AND METHODS

The institutional review board approved this research and waived informed consent from the patients. Two radiologists blinded to the pathologic assessment of malignancy or parenchymal invasion of IPMN retrospectively evaluated CT images of 61 consecutive surgically resected tumors (26 adenomas, 15 noninvasive carcinomas, and 20 invasive carcinomas) in patients who underwent multiphase contrast material-enhanced CT with 0.5- or 1-mm collimation. The findings were statistically analyzed by using univariate and multivariate analyses, with the optimal cutoff levels of each continuous parameter determined by generating receiver operating characteristic curves.

RESULTS

The following findings showed significant differences among the three groups: maximum diameter of the main pancreatic duct (MPD), size (length of major axis) of the largest mural nodule in the MPD or in any associated cystic lesion, abnormal attenuating area in the surrounding parenchyma, calcification in the lesion, protrusion of the MPD into the ampulla of Vater, and bile duct dilatation. An MPD diameter of 6 mm or larger, a mural nodule of 3 mm or larger, and an abnormal attenuating area were independently predictive of malignancy. A mural nodule of 6.3 mm or larger in the MPD and an abnormal attenuating area were independently predictive of parenchymal invasion. According to these criteria, the sensitivity, specificity, and accuracy for identifying malignancy were 83%, 81%, and 82% and for identifying parenchymal invasion were 90%, 88%, and 89%, respectively.

CONCLUSION

Multisection CT is useful for distinguishing among adenoma, noninvasive carcinoma, and invasive carcinoma in patients with IPMN.

[Pancreas. Part I: congenital changes, acute and chronic pancreatitis]

The pancreas develops from ventral and the dorsal buds, which undergo fusion. Failure to fuse results in pancreas divisum, which is defined by separate pancreatic ductal systems draining into the duodenum. Risk of developing pancreatitis is increased in pancreas divisum because of insufficient drainage. MR cholangiopancreatography (MRCP) is the technique of choice for detecting pancreas divisum non-invasively. Annular pancreas is the result of incomplete rotation of the pancreatic bud around the duodenum with the persistence of parenchyma or a fibrous band encircling (and sometimes stenosing) the duodenum. Acute pancreatitis is usually caused by bile duct stones or alcohol abuse. The Atlanta classification differentiates between mild acute and severe acute pancreatitis associated with organ failure and/or local complications such as necrosis, abscess or pseudocyst. Contrast-enhanced multi-detector row CT is the method of choice to assess the extent of disease. Balthazar et al.'s CT severity index assesses the risk of mortality and morbidity. In acute pancreatitis, the role of MRCP is mainly limited to finding bile duct stones in patients with suspected biliary pancreatitis. Chronic pancreatitis results in relentless and irreversible loss of exocrine (and sometimes endocrine) function of the pancreas. MDCT even shows subtle calcifications. MRCP is the method of choice for non-invasive assessment of the duct. Inflammatory pseudotumor in chronic pancreatitis and groove pancreatitis are difficult to differentiate from pancreatic cancer. In these cases, multiple imaging methods such as MDCT, MRI and endosonography including biopsy may be used to make a diagnosis.

Management of pancreas divisum

Pancreas divisum is the most common congenital anomaly of the pancreas. Abnormal hedgehog protein signaling appears related to the formation of several pancreatic malformations, including annular pancreas, pancreatic-biliary malunion, pancreatic rests, and pancreas divisum. Pancreas divisum by itself should not necessarily require intervention. A careful evaluation should be performed to exclude other causes of symptoms. If the patient is asymptomatic, no further evaluation is necessary. However, a significant percentage of patients with pancreas divisum and acute recurrent pancreatitis benefit from intervention. Surgical sphincteroplasty and endoscopic interventions appear similar in outcome. Thus, endoscopic intervention with prophylactic temporary stenting is advised as initial therapy. Surgery should be reserved for patients with chronic pancreatitis.

Diagnostic value of curved multiplanar reformatted images in multislice CT for the detection of resectable pancreatic ductal adenocarcinoma

The purpose of this study was to assess the usefulness of curved multiplanar reformatted (MPR) images obtained by multislice CT for the depiction of the main pancreatic duct (MPD) and detection of resectable pancreatic ductal adenocarcinoma. This study included 28 patients with pancreatic carcinoma (size range 12-40 mm) and 22 without. Curved MPR images with 0.5-mm continuous slices were generated along the long axis of the pancreas from pancreatic-phase images with a 0.5- or 1-mm slice thickness. Seven blinded readers independently interpreted three sets of images (axial images, curved MPR images, and both axial and curved MPR images) in scrolling mode. The depiction of the MPD and the diagnostic performance for the detection of carcinoma were statistically compared among these images. MPR images were significantly superior to axial images in depicting the MPD, and the use of both axial and MPR images resulted in further significant improvements. For the detection of carcinoma, MPR images were equivalent to axial images, and the diagnostic performance was significantly improved by the use of both axial and MPR images. High-resolution curved MPR images can improve the depiction of the MPD and the diagnostic performance for the detection of carcinoma compared with axial images alone.