Assessment of the Usefulness of SMI (Superb Vascular Imaging) for the Characterisation of Pancreatic Cystic Tumours (IMAKYST) (IMAKYST)

Pancreatic cysts are becoming increasingly common in the general population. They are most often discovered incidentally during cross-sectional abdominal imaging.

There are different types of pancreatic cystic lesions, each with distinct risks of progression. Lesions with the potential for malignant transformation are typically mucinous lesions (papillary intraductal mucinous neoplasms of the pancreas [PIMN] and mucinous cystic neoplasms [MCN]), formerly known as mucinous cystadenomas), whereas non-mucinous lesions (serous cystadenomas [SCs] and pseudocysts) are entirely benign and do not require monitoring.

SC typically presents as a solitary cyst with no communication with the Wirsung duct, appearing microcystic with central calcification. This typical appearance is not always present, and SC can mimic a mucinous lesion. In such cases, imaging and echoendoscopy findings are not discriminatory. Histological and biochemical analysis of the fluid obtained during cyst aspiration may be helpful, but the specificity is usually insufficient to make a definitive decision regarding the absence of surgery and the need for monitoring. These diagnostic difficulties mean that one in three patients with SC undergo unnecessary surgery, with significant morbidity and mortality.

There are currently two highly effective techniques for diagnosing SC:

• Endocystic microbiopsy, which has a diagnostic accuracy of nearly 100% but a high complication rate (around 10%). It is no longer recommended except in exceptional cases.
• Needle-based confocal laser endomicroscopy (nCLE), which has 100% specificity for the diagnosis of SC.

SC is a lesion characterised by intense microvascularisation present in all the cyst walls and throughout the entire peripheral capsule of the cyst. SMI is a new ultrasound modality capable of visualising microvascular flow without the need for contrast injection, unlike nCLE.

The Mermoz Endoscopy Centre will be equipped with an ultrasound console enabling SMI to be performed during an echoendoscopy examination. This technology is now available on the new Aplio i800 EUS console (Canon-Olympus).

To date, no data has been published on the potential of SMI for characterising and diagnosing SC. This is why this clinical investigation is being conducted.