European Radiology: How to noninvasively distinguish benign and malignant Vater ampullary stenosis?

The ampulla of Vater is a complex structure located medially in the second part of the duodenum and formed by a peritoneal duct surrounded by the distal common bile duct (CBD) and the main pancreatic duct (MPD) or Oddi sphincter
.
Various benign and malignant lesions can occur in the ampulla
of Vater.
Ampullary carcinoma is the most common malignancy involving the tissue surrounding the ampulla of Vater, which is often detected due to biliary obstruction and is often detected early
。

Therefore, this type of cancer has a better prognosis than other malignancies such as CBD cancer or pancreatic head cancer due to its small size, the early stages of the tumor at the time of diagnosis, and the ability to achieve complete surgical removal.

However, because tumors are usually small and often resemble other benign lesions in appearance, diagnosis is relatively difficult
.

Currently, various imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI), endoscopic ultrasonography or endoscopic retrograde cholangiopancreatography (ERCP) are used in clinical practice and have been evaluated
in several studies.
Endoscopic ultrasound (EUS) or endoscopic retrograde cholangiopancreatography is very valuable
in determining the cause of Vater's ampullary stenosis and in treating it.

However, endoscopic surgery is relatively invasive and postoperative complications such as pancreatitis, cholangitis, or perforation can occur.

MRI has a high soft-tissue resolution and provides accurate ampullary anatomical details of Vater, but it is difficult to be widely used due to its difficult availability, high cost, susceptibility to motion artifacts, and long research time.

Multi-row CT scans are more readily available, less expensive, and have good spatial resolution than MRI, so they are widely used in the primary evaluation
of Vater's ampullary stenosis.
However, only a few studies reported the usefulness of CT imaging results in distinguishing benign and malignant Vater ampullary stenosis, and the results of multivariate analyses varied
.

A study published in the journal European Radiology explored the best enhanced CT imaging and clinical signs to distinguish benign and malignant Vater ampullary stenosis, and combined these signs to construct a nomogram that provides technical support
for rapid, accurate, and noninvasive clinical assessment of benign and malignant Vater ampullary stenosis.

 This retrospective study included 152 patients with Vater's ampullary stenosis (98 benign, 54 malignant)
who underwent enhanced CT scanning.
Various imaging results around Vater's ampullary duct, bile duct, main pancreatic duct, and pancreas were evaluated, and clinical results
including the presence or absence of jaundice, carbohydrate antigen 19-9 levels, and history of gallbladder resection were collected.
Among them, logistic regression analysis using univariate and multivariate was used to determine statistically significant results
.
A nomogram was constructed to distinguish benign and malignant Vater ampulla and performed internal validation
.

Multivariate analysis showed jaundice (odds ratio [OR]: 17.
33, P<0.
001), presence of Vater ampullary masses (OR: <b12>24.
40, P<0.
001),</b12> and non-similar enhancement of Vater's ampullary canal to duodenum (OR: 31.
96, P= 0.
003) and proportional dilation of the bile ducts (OR: 7.
98, P=0.
001) were independent factors predicting malignant Vater ampullary stenosis and were used to construct nomograms
.
Among them, the non-similarity of the Vater ampullary tube to the duodenum is enhanced, showing the highest predicted points
on the OR and nomograms.
The calibration plot shows a good agreement between the predicted probabilities and the actual incidence of malignant Vater ampullary stenosis, as validated internally.

Image from a 70-year-old man presenting with abdominal pain
.
Coronary reconstruction (a) and axial images (b) of portal phase enhanced CT show proportional dilation of the bile ducts (arrow) without visible Vater ampullary mass (arrow).

The patient's serum total bilirubin level is within the normal range
.
This patient has only one important independent predictor variable (proportional bile duct ectasia), and according to the nomogram, the probability of malignant Vater ampullary duct stenosis is less than 0.
1
.
The patient underwent an endoscopic biopsy of the Vater ampullary canal and was shown to have benign Vater ampullary stenosis
.

This study shows that predictive nomograms using enhanced CT imaging results and clinical results can be used to distinguish benign and malignant Vater ampullary stenosis, which provides a reference for
non-invasive and accurate clinical evaluation.

Original source:

Ji Eun Lee,Seo-Youn Choi,Min Hee Lee,et al.
Differentiating between benign and malignant ampullary strictures: a prediction model using a nomogram based on CT imaging and clinical findings.
DOI:10.
1007/s00330-022-08856-7