What is Microwave Ablation?
In this blog series on ablation, we will be looking at Microwave Ablation (MWA). MVA is a form of thermal ablation used to treat cancer. Specifically, it is the use of electromagnetic waves in the microwave energy spectrum in order to produce heat to promote tissue necrosis (tissue death). For this procedure to happen, an imaging device and probe are needed. During this procedure, the probe is first placed on the tumor with the help of an imaging device such as an ultrasound or CT scan. Then, the probe emits microwaves which creates intense heat leading to the death of the harmful tissue. Microwave ablation has been seen to be favored more by medical professionals due to its advantages over RFA. Some advantages include speed and greater treatment area. MVA has been seen to be completed within 10 minutes for tumors that would otherwise take up to 90 minutes with RFA. This difference in time is extremely important for patient safety because it limits the amount of necessary exposure time to the extreme heat necessary to destroy the healthy tissue.
Challenges with Microwave Ablation
While ablation is a relatively safe procedure because of its minimally invasive nature, there are still some challenges that can occur as a result of MVA. Some complications that can occur as a result of MVA are infection, inflammation, bleeding and thermal damage to surrounding tissues and organs. The bleeding that occurs due to not closing off veins around the tumor during MVA can be avoided if the temperature being used throughout the procedure is continuously monitored. In addition to avoiding bleeding, thermal damage can also be avoided. The difference of temperature of what is required to destroy harmful tissue and what is necessary to damage surrounding areas is very slim. Therefore, precise real time temperature monitoring is key in order to preserve surrounding areas from damage as a result of this procedure.
How Can Fiber Optics Help?
The sensors used today are broadly categorized as invasive or contact and non-invasive or non- contact. Non- invasive methods use Ultrasound imaging, Computed Tomography (CT) or Magnetic Resonance (MR). Although these methods provide advance image-based temperatures maps, the results are not real time and are not compatible with all devices. Invasive sensors like thermocouples, require it to be inserted directly into the target tissue to measure the temperature. While they are cost-effective than imaging system, there is significant measurement error that needs to be offset. Additionally, thermocouples are slow to respond to the rapid temperature changes found in microwave ablation procedures.
Fiber optic sensors (FOS) are the state-of-the-art invasive sensors extensively used today in the RF ablation procedures. There are different FOS technologies available, like Fiber Bragg Grating (FBG), however Fiber Point Sensors are extensively used for temperature measurement. These sensors are small (200- 500 µm) for easy integration into existing medical equipment with wide temperature measurement range (greater than +/-100 C).
Specifically, in microwave ablation procedures, they can help monitor the temperature in order to prevent thermal damage of surrounding tissues and organs. This is essential to ensure patient safety throughout this procedure. In addition, the fast response time of the FOS allows for the temperature to be monitored in real time leading to corrections being made if necessary.
The fibers are also biosafe and chemically inert. This allows for drugs and chemicals used in treatments to not be altered to accommodate fiber monitoring. They also respond to rapid changes in the local environment, which is about 30ms without compromising on the accuracy of the reading ( +/ 0.2 C).These advantages makes them highly coveted in microwave ablation and increases the effectiveness of treatment for patients.
Outlook: The trend towards minimally invasive surgery is increasing, which requires variety of minimally invasive medical devices with safe, precise monitoring for successful treatment. FOS is an ideal fit with capabilities and features that cannot be otherwise obtained using thermocouples. The FOS sensor design and development are not trivial, and proper material selection, design, biocompatibility, patient safety, and other issues must be considered.
Rugged Monitoring LSENSB
Rugged Monitoring (RM) has deep expertise in the medical FOS technology and developed the LSENSB sensor tailored for this application. LSENSB sensor was designed for advance research applications that demand high sampling rate( ~30ms). There are several variants of LSENSB sensors already in the market used by research institutions, surgeons, and equipment manufacturers. RM is a pioneer in making custom fibers that would easily integrate into existing equipment. To learn more about LSENSB, please visit the medical solutions.