Objectives

- To review the pancreas embryology including the two ventral buds-theory

- To know the clinical implication of congenital variants and anomalies of the pancreas

- To review diagnostic imaging of most common variants and anomalies

- To discuss imaging technics allowing more precise ductal configuration study

- To review the subtypes and classifications attempts of annular and circumportal pancreas

Background

As some developmental anomalies of the pancreas can lead to diseases and anatomical variants mimic lesions or result in surgical risks, radiologists should be familiar with the main pancreatic variants.

Imaging findings OR Procedure findings

- Usual anatomy and embryologic development

- Anomalies and variations (of development, rotation and fusion) of the pancreatic buds :

> Total or partial agenesis

> Ectopic pancreas

> Annular pancreas

> Circumportal pancreas

- Anomalies and variations of the pancreatic ducts :

> Pancreatobiliary junction

> Downstream ductal configuration

> Pancreas divisum

> Pancreas bifidum

- Anomalies of parenchymal development and cell differentiation :

> Focal or sectorial: focal fatty infiltration versus lipomas, focal fatty sparing, contour variation (prominent focal exophytic lobulation between peritoneal reflections)

> Diffuse: genetic (Shwachman-Diamond, Johanson-Blizzard) versus acquired lipomatous infiltration

- Anomaly of the splenic anlage: intrapancreatic accessory spleen

Conclusion

Pancreatic variants and developmental anomalies can be diagnosed accurately using CT and/or MR imaging. The understanding of their embryological origins may help radiologists in their diagnosis.

Purpose

The aim of this study was to describe the imaging features of successive annular pancreas cases with an emphasis on their ductal configurations, in order to determine between the two main embryological theories of annular pancreas, and to illustrate the three main ductal types believed to result from the two-ventral bud theory initially described by Lin.

Material and methods

By searching retrospectively our institution’s database between 2007 and 2019, we identified 17 patients with annular pancreas who underwent MRI and/ or CT scans. Ductal configurations were assessed in consensus by two radiologists using an expanded version of Lin’s annular pancreas classification: type I (divisional annular pancreas), type II (branch annular pancreas) or type III (main duct annular pancreas). Circumstances and clinical implications of the diagnosis were collected.

Results

We found 5 patients with type I (29.4%), 11 patients with type II (64.7%) and one patient with type III (5.9%). The theory of a paired-ventral bud appeared to be the most plausible as it can explain the presence of two major ducts in the pancreatic head and annulus. None of the patients had upper GI obstruction symptoms directly attributable to annular pancreas. Pancreatic diseases were diagnosed in 6 cases (35.3%). The presence of an annular pancreas had a significant clinical impact for 3 patients, regarding the diagnosis (2 cases) or the treatment management (1 case).

Conclusion

This study reported 17 annular pancreas cases matching Lin’s classification in 3 types presumably resulting from the abnormal persistence of the left part of a paired-ventral bud.

Purpose

To identify CT findings associated with successful conservative treatment of closed loop small bowel obstruction (CL-SBO) due to adhesions or internal herniation.

Material and methods

The local institutional review board approved this study while waiving informed consent. Clinical and CT data were collected retrospectively for 96 consecutive patients with a CT diagnosis of CL-SBO due to adhesions or internal herniation established by experienced radiologists who had no role in patient management. Mechanical obstruction with at least two transition zones on the bowel at a single site defined CL-SBO. Two radiologists blinded to patient data independently performed a retrospective review of the CT scans. The patient groups with successful versus failed initial conservative therapy were compared. Univariate and multivariate analyses were performed to look for CT findings associated with successful conservative therapy. Interobserver agreement was assessed for each CT finding.

Results

Of the 96 patients, 34 (35%) underwent immediate surgery and 62 (65%) received first-line conservative treatment, which succeeded in 19 (31%) and failed in 43 (69%). The distance between the transition zones was the only independent predictor of successful conservative therapy (odds ratio, 4.6 when ≥8 mm; 95% confidence interval [95%CI], 1.2-18.3). A distance ≥ 8 mm had 84% (95%CI, 60-97) sensitivity and 46% (95% CI, 31-62) specificity for successful conservative treatment. The correlation coefficient for the distance between transition zones was fair (r=0.46).

Conclusion

CL-SBO can resolve without surgery. When there is no CT sign of ischemia, the distance between the transition zones should be assessed.

Purpose

To identify CT findings associated with successful conservative treatment of closed loop small bowel obstruction (CL-SBO) due to adhesions or internal herniation.

Material and methods

The local institutional review board approved this study while waiving informed consent. Clinical and CT data were collected retrospectively for 96 consecutive patients with a CT diagnosis of CL-SBO due to adhesions or internal herniation established by experienced radiologists who had no role in patient management. Mechanical obstruction with at least two transition zones on the bowel at a single site defined CL-SBO. Two radiologists blinded to patient data independently performed a retrospective review of the CT scans. The patient groups with successful versus failed initial conservative therapy were compared. Univariate and multivariate analyses were performed to look for CT findings associated with successful conservative therapy. Interobserver agreement was assessed for each CT finding.

Results

Of the 96 patients, 34 (35%) underwent immediate surgery and 62 (65%) received first-line conservative treatment, which succeeded in 19 (31%) and failed in 43 (69%). The distance between the transition zones was the only independent predictor of successful conservative therapy (odds ratio, 4.6 when ≥8 mm; 95% confidence interval [95%CI], 1.2-18.3). A distance ≥ 8 mm had 84% (95%CI, 60-97) sensitivity and 46% (95% CI, 31-62) specificity for successful conservative treatment. The correlation coefficient for the distance between transition zones was fair (r=0.46).

Conclusion

CL-SBO can resolve without surgery. When there is no CT sign of ischemia, the distance between the transition zones should be assessed.