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What is intraoperative ultrasound?

It is an ultrasound performed during surgery. It is divided into simple intraoperative ultrasound (IOUS – Intraoperative Ultrasound) and intraoperative ultrasound with the use of contrast ultrasound (CE – IOUS – Contrast – Enhanced Intraoperative Ultrasound).

When is it necessary to use it?

It is necessary to be performed during surgery for tumor staging. Studies have shown that if we also use intravenous contrast ultrasound during surgery, we can visualize new tumors that have not been detected in the preoperative examination with other imaging methods (CT and MRI). The sensitivity of the method using contrast ultrasound reaches 99%.

Technique

• Initially, the anatomy of the liver is visualized, the position of the vessels is assessed, and the intrahepatic biliary tree is assessed.
• Then we observe the pathology of the liver (presence of focal lesions, relationship of the foci to the vessels of the liver, possible thrombosis of the vessels).
• The subsequent addition of contrast ultrasound can give us new information, e.g. to see additional infrasound foci (metastatic) in the liver and the surgeon may need to modify the surgical plan.
• In the event that radiofrequency ablation (RFA) or microwave ablation (MWA) of the tumors is required during surgery, we immediately check with the contrast medium whether the result is successful. If the foci have not died, we repeat the cauterization and recheck the result.
• In patients with colon cancer who have received preoperative chemotherapy that makes the metastases indistinct, the use of intraoperative ultrasound with contrast is considered necessary for the best surgical result.

SCONCLUSION:

The use of contrast in intraoperative ultrasound (CEIOUS) in liver cancer has an important role in the detection and staging of tumors as well as in the control of vascular patency. It is also useful for monitoring the outcome of thermocautery (RFA – MWA) due to its high resolution and real-time imaging.

The use of contrast agent is considered essential in patients with metastatic liver disease who have undergone chemotherapy for the visualization of metastatic focal lesions and the best surgical outcome.