European Radiology: Enhanced ultrasound in the diagnosis of solid pancreatic lesions

At this stage, the clinical diagnosis of solid lesions of the pancreatic head (SPHL) is still a huge challenge
.
Although the most common SPHL is pancreatic ductal adenocarcinoma (PDAC), both neuroendocrine tumors (NETs) and inflammatory lesions can exhibit similar clinical features[
].
Inflammatory masses often have a background of chronic pancreatitis or autoimmune pancreatitis.

No biochemical or immunological markers have been found to accurately predict and evaluate benign and malignant SPHL.

Grayscale ultrasound (US) features such as large size and irregular edges may be seen in malignant lesions
.

However, US is challenging
to detect pancreatic lesions.
It has been reported that certain imaging features of contrast-enhanced computed tomography (CECT) and magnetic resonance imaging (MRI), including enhanced features and pancreas/bile duct obstruction, can be featured as features of SPHL
.
Although new technologies based on CT and MRI have shown good diagnostic results in describing pancreatic lesions, these techniques are not widely available
in clinical practice.
Even preoperative fine-needle aspiration cytology (FNAC) and biopsy may not yield representative tissue, resulting in a high
false-negative rate.

With the development of ultrasound technology, contrast-enhanced ultrasound (CEUS) is increasingly used in the abdomen
.
Due to its blood pool nature, CEUS is very sensitive in characterizing tissue blood vessels and can help characterize and strengthen blood vessels within pancreatic lesions, including parietal nodules
within pancreatic cystic lesions.
The published literature suggests a potential clinical role for CEUS in the characterization of pancreatic lesions.

Because SPHL exhibits unique clinical and imaging findings, a study published in the journal European Radiology explored the role and value of CEUS in describing SPHL, providing technical support for rapid and accurate diagnosis of benign and malignant SPHL in clinical practice
.

This prospective study included patients
with SPHL who were continuously evaluated for pancreatic CEUS.
CEUS recorded results include enhancement patterns (degree, integrity, centripetal enhancement, and percent enhancement) and the presence of
central vessels.
In addition, peak time (TTP) and purge time (WT)
are recorded.
The final diagnosis is based on histopathology or cytology
.
Multivariate analysis is performed to determine parameters
significantly associated with pancreatic ductal adenocarcinoma (PDAC).

A total of 98 patients (median age 53.
8 years, 59 men) were evaluated
in this review.
The final diagnosis was PDAC (n = 64, 65.
3%), inflammatory mass (n = 16, 16.
3%), neuroendocrine tumor (NET, n = 14, 14.
3%), and other tumors (n = 4, 4.
1%)
.
Low-strengthening, incomplete reinforcement, and centripetal reinforcement are more common in PDAC than non-PDAC lesions (p = 0.
001, p = 0.
031, and p = 0.
002, respectively).

Central vessels are present in more non-PDAC lesions (p = 0.
0001).

A low enhancement of < 30% in CEUS has a sensitivity and specificity of 80.
6% and 67.
7%
for PDAC, respectively.
There was no significant difference between
TTP and WT in PDAC and non-PDAC lesions.

However, WT in PDAC is significantly shorter (p = 0.
011)
compared to NET.
In multivariate analysis, the absence of central vessels was significantly associated
with PDAC diagnosis.

Figure Pancreatic neuroendocrine tumors
.
CT with enhanced axial position in the A, B, and portal phases shows a strengthened mass (arrow)
at the head of the pancreas.
C-F CEUS shows highly intensive lesions (arrows, C-E) with central vessels (arrows, F).

Micrograph of Esin-stained sections of G hematozoin showed poorly differentiated neuroendocrine carcinoma in almost every cell, showing positive for CD 56 and positive for Ki67 nuclei

This study suggests that CEUS is an effective imaging tool for evaluating SPHL, in which the enhanced features of CEUS distinguish PDAC from non-PDAC lesions
.
Therefore, incorporating CEUS into the diagnostic process for patients with SPHL can further reduce the occurrence
of misdiagnosis.

Original source:

Pankaj Gupta,Pratyaksha Rana,Yashi Marodia,et al.
Contrast-enhanced ultrasound of solid pancreatic head lesions: a prospective study.
DOI:10.
1007/s00330-022-08854-9