**1. Introduction**

Pancreatic cancer is one of the most aggressive types of cancer in the abdominal cavity with poor survival rates below 10% [1]. The reasons for the poor prognosis range from late detection of the cancer, vascular invasion, and difficult access due to the surrounding structures at risk. Attributable to the late detection, 80% of patients are not eligible for resection as they are diagnosed with locally advanced (30%), or metastatic pancreatic cancer (50%) [2]. Patients with locally advanced pancreatic cancer can benefit from alternatives such as radiotherapy, high-intensity focused ultrasound (HIFU), or ablation as a complementary treatment. Over the last decade, local ablative techniques have been used more frequently in patients without metastatic disease. Several techniques, all of which were primarily introduced in order to ablate liver metastases are in clinical use. Radiofrequency or microwave ablation, the two most widely established techniques, use thermal

energy. However, high temperatures not only destroy tumor tissue but also increase morbidity if applied too close to structures such as bile duct, portal vein, superior mesenteric vein, celiac artery, or superior mesenteric artery, which all run in close proximity to the pancreas [3–5]. On the other hand, irreversible electroporation (IRE) leads to cell death by using high-voltage electrical pulses without destroying vascular collagen [6]. IRE, in contrast to thermal ablative techniques, always requires at least two needles, and metallic implants and cardiac arrhythmias are contraindications for this technique [6]. Possible morbidity arises either from needle tract injuries (bleeding, local infection due to intestinal puncture) or from energy application-associated thrombosis or necrotic tissue leading again to infection.

Local ablative techniques are generally used in the context of a multimodal treatment. Preoperative chemotherapy has been established in the most recent years for the multimodal treatment of borderline resectable and locally advanced pancreatic cancer to increase resectability [7]. Neoadjuvant chemoradiation has also been increasingly performed with favorable long-term outcomes [8]. However, response to these treatments cannot be evaluated adequately using radiologic criteria so far, thus directing decision-making regarding resection [9]. Similarly, IRE for pancreatic cancer has been facing the same problems, lacking reliable radiologic and clinical markers for the detection of response. Nevertheless, current studies have indicated that the antitumoral efficacy of IRE may be identified using immunological parameters supporting the oncological benefits of IRE, additional to the electroporative effects of this ablative method on tumor cells [10, 11].

Neoadjuvant treatment for borderline resectable or locally advanced pancreatic cancer may allow resection in up to 78% of selected patients [12]. In this case, R0 resection status has been previously described as essential to reduce local and systemic recurrence and prolong survival [13]. However, due to local extension of tumor to involve vascular structures, R0 resection is more difficult to be achieved in patients with advanced disease and positive resection margins have been frequently been underestimated [14]. Therefore, in advanced disease, multimodal treatment concepts including induction therapy, followed by resection and concomitant IRE at the surgical margins have been proposed [15]. Several studies have shown the safety and feasibility of margin accentuation with intraoperative IRE during resection for borderline resectable and locally advanced pancreatic cancer. According to this concept, intraoperative IRE before complete transection could accentuate the negative-margin dissection of the retroperitoneal margin and its surrounding perivascular soft tissue as well as the perineural and mesenteric tissue adjacent to critical vascular structures [16, 17].

Additionally, current studies have even provided most promising results in terms of reduced local and distant progression, and superior overall survival when pancreatic resection and IRE are combined [16, 17]. Careful selection of patients eligible for this strategy, together with modern systemic therapy regimens, may increase resectability and improve oncological outcomes in the near future [18].

In patients with borderline resectable and locally advanced pancreatic cancer, IRE was also identified as a valuable tool to offer consolidative disease control and symptom relief such as pain control and to support eradiation of the malignant lesion [19]. However, only few studies have evaluated the quality of life following IRE for pancreatic cancer [20]. In a recent study, 84 patients undergoing IRE for locally advanced pancreatic cancer were enrolled. Quality of life assessment indicated that IRE therapy does not impair the quality of life in the short term. Adverse post-interventional events such as increased insomnia and constipation

*Computer Assistance in the Minimally Invasive Ablation Treatment of Pancreatic Cancer DOI: http://dx.doi.org/10.5772/intechopen.93226*

at 3 months and diarrhea at 6 months after IRE are most probably related to other clinical factors such as chemotherapy-associated toxicity. Therefore, IRE is not expected to adversely affect long-term quality of life in this patient cohort [21]. Further studies are required to examine quality of life following IRE in the long term.

The latest numbers on published pancreatic IRE cases investigated by Moris et al. [22] counted a total of 498 treatments and accentuate the lack of clinical evidence as an indicator for low numbers in pancreatic IRE treatments compared to other fields of application. While the procedures were either conducted percutaneously (n = 232) or open (n = 262), the laparoscopic approach (n = 4) played only a minor role [22].

IRE application requires the user to place the needles within a certain distance and angle to each other [23]. This makes the use of the ablation technique very difficult, especially when navigating the needles close to structures at risk. With respect to the laparoscopic needle placement, the long needles and decreased field of view add additional complexity to this task.

### **2. Navigate the pancreas**

The workflow for pancreatic IRE treatments is divided into a preoperative planning and intraoperative navigation phase.

#### **2.1 Preoperative needle planning**

Tomographic images are acquired to identify the structures at risk in proximity to the tumor. These structures include vessels, bile ducts, and organs as visualized in **Figure 1**.

To assess suitable patients for the IRE treatment, patients are screened to determine possible access windows and the needle configuration depending on the treatment approach [24]. In addition, 3D reconstructions derived from the original images enhance the spatial understanding during the planning of the trajectories.

#### **Figure 1.**

*Axial computed tomography image of a patient with LAPC where the tumor encapsulates the celiac artery.*

However, information regarding the preoperative IRE planning phase remains sparse in current literature.

#### **2.2 Intraoperative needle placement**

While the surgical (open or laparoscopic) approach provides advantages to mobilize the structures at risk to gain a better access window for the needles, the review of all eligible studies until August 2018 identified a morbidity of 36% for the surgical approach (89/247) compared to 24.3% for the percutaneous IRE approach (56/230) [22].

Atraumatic needle placement is key for a successful treatment outcome; thus, the needles need to be monitored with computed tomography (CT), magnetic resonance imaging (MRI), fluoroscopy, or with live ultrasound (US) depending on the treatment approach. As of today, there is no comparative study investigating CT vs. US-guided IRE needle placement. Both modalities may be used to check for proper needle placement [19, 25, 26]. However, since preoperative planning is typically conducted on CT images, it may be considered as the primary modality for guiding needle placement during the percutaneous intervention. The main disadvantage of increased radiation can be considerably reduced by complementing computer-assisted navigation, as will be discussed later [27]. In addition, CT-guided procedures are less dependent on the experience of the user and offer the possibility to check immediately for post-interventional complications such as bleeding or thrombosis [27, 28].

The flexibility of the needles represents an additional challenge to keep the needles on track during the insertion. Dedicated hardware tools provide additional support to guide the needle to the specific location by reducing bending artifacts. The most basic form of needle guidance is the usage of the needle spacer provided by AngioDynamics (Latham, New York) to achieve the desired interelectrode distance, yet it does not prevent the needle from bending during the insertion [29]. Martin et al. [30, 31] emphasize the usage of a needle guide attached to the biplanar US probe for more precise needle placement and to keep the needle in the ultrasound plane. However, this approach limits the spatial freedom of the ultrasound transducer due to the static properties of the guide and aggravates the monitoring of structures at risk.

### **3. The doctor's opinion**

To elaborate on the necessity of dedicated planning and navigation assistance, we conducted a questionnaire with eight medical doctors (MDs). The study population consisted of MDs with specialty in HPB surgery (n = 7) and surgical oncology (1) active in USA (1), India (1) Turkey (1), Germany (1), Austria (1), and Switzerland (3). The MDs performed between 30 and 120 pancreatic surgeries annually (average value of 70 surgeries per year). The yearly number of IREs was situated between 0 and 20 treatments with an average number of 4.5. All questioned doctors performed the preoperative planning of IRE cases solely on tomographic images and occasionally in combination with reconstructed 3D models. Due to the complex anatomy with varying patient-specific structures at risk, all MDs argue in favor of a preoperative IRE planning tool, which makes use of imaging data in combination with reconstructed 3D models to verify the feasibility of needle configurations. Most of the pancreas specialists see a need for minimally invasive pancreas IRE (87.5%) as well as for intraoperative needle navigation (100%) (illustrated in **Figure 2**) [32].

*Computer Assistance in the Minimally Invasive Ablation Treatment of Pancreatic Cancer DOI: http://dx.doi.org/10.5772/intechopen.93226*

#### **Figure 2.**

*Result from questionnaire where the need for dedicated tools is highlighted to assist the clinician in the perioperative procedure.*
