How it Works – Learn more about Laser Ablation in Neurosurgery

In September last year, the CLS laser ablation system for neurosurgical procedures was cleared by the FDA. Since then, development has progressed rapidly: CLS´s partner and global distributor ClearPoint Neuro is now commercializing the system under the brand ClearPoint™ Prism Neuro Laser Therapy System in the US market, a study is ongoing at Skåne University Hospital in Sweden, and recently the hospital published a memo in which the advantages of operating on patients with certain types of brain tumors inside the MRI scanner were clearly highlighted. But how does it actually work? We explain below.

How it works in short

Laser ablation is a minimally invasive procedure and when using the system by CLS/ClearPoint for neurosurgery the whole procedure is carried out inside the MRI scanner. To reach the diseased tissue, such as a brain tumor, the surgeon drills a small hole, with a diameter of only a few millimeters, through the patients’ skull. With support from a positioning system (by ClearPoint Neuro), the neurosurgeons then use images from the MRI scanner to guide the thin laser applicator through the patient´s brain and into the diseased tissue. Once the laser applicator is accurately placed into the target tissue the actual treatment can start. The tissue is heated in a controlled way so that the cancer cells are coagulated, and tumor death occurs. 

While the patient preparations and positioning of the laser applicator into the exact planned position in the patient’s brain is a complex process, the actual laser ablation is generally very quick and done in just a few minutes.

Figure 1. The team leading the study at Skåne University Hospital (SUS) evaluating the new method to treat hard-to-reach brain tumors with laser surgery inside a magnetic camera.

From the left: senior physician Hjalmar Bjartmarz, specialist physician Irena Grubor, and senior physician Peter Siesjö.

Monitoring and controlling the laser ablation

For optimal outcome the heating needs to be delivered in a controlled way. To complicate things there is no strong correlation between a certain dose of energy applied to the target tissue, and the actual temperature reached. Factors such as tissue composition, color of the tissue and blood flow make it impossible to predict tissue temperature with the accuracy needed for a safe and efficient treatment.

This is why a thermometry software, such as CLS Thermoguide™ is an invaluable tool. During the laser ablation, TRANBERG® Thermoguide Workstation provides a detailed map over the temperature distribution in the brain in near real time. The software also estimates the tissue damage and displays the corresponding estimated ablation area. To give the surgeon a complete overview and control of the procedure these images are displayed in several planes.

Figure 2. TRANBERG® Thermoguide Workstation uses non-invasive, near real-time MRI thermo-metry to monitor temperature changes and duration. This information is used to calculate the thermal damage estimate.

The upper images display calculated temperature distribution in degrees Celsius in two directions, and the lower images display the thermal damage estimate. 

Safety guards for protection of sensitive structures

Often sensitive structures in the brain, which may control vital body functions, are near the diseased tissue. For maximum safety and protection of such structures Thermoguide also enables the surgeon to set temperature guarding checkpoints. Whenever a checkpoint threshold is reached, the laser immediately shuts off automatically. In this way the treatment can be efficiently performed and at the same time minimizing the risk of damaging nearby critical structures.

Benefits for the patients

In summary there are several great advantages using laser ablation in neurosurgery:

  • Neurosurgeons can now treat patients they were previously unable to help.
  • Small tumors deep in the brain that are not available for resection can be reached using laser ablation.
  • Compared to traditional surgery laser ablation it is more gentle, which means that the risk of infections is reduced and that the recovery is faster.
  • Moreover, with CLS´s and ClearPoint Neuro’s combined systems, the whole procedure is carried out inside the MRI room avoiding transportation of the patient back and forth to an operating theatre.

Recommended further reading

Memo from Skåne University Hospital (English version, issued 2023-01-30)

Link to ClearPoint Neuro´s website on the PRISM Neuro Laser Therapy System:

Article in Läkartidningen on how interventions in the brain have become more precise and less risky (in Swedish, 2023-01-26) 

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