Recent Advances in Robot-Assisted Surgery: Soft Tissue Contact Identification Tam´ as D. Nagy ∗ and Tam´ as Haidegger ∗† ∗ Antal Bejczy Center for Intelligent Robotics, ´ Obuda University, Budapest, Hungary † Austrian Center for Medical Innovation and Technology (ACMIT), Wiener Neustadt, Austria Email: {tamas.daniel.nagy, tamas.haidegger}@irob.uni-obuda.hu Abstract—Robot-Assisted Minimally Invasive Surgery (RAMIS) is becoming standard-of-care in western medicine. RAMIS offers better patient outcome compared to traditional open surgery, however, the surgeons’ ability to identify the tissues with the sense of touch is missing from most robotic systems. Regarding haptic feedback, the most promising diagnostic technique is probably palpation; a physical contact examination method through which information can be gathered about the underlying structures by gently pressing with the fingers. In open surgery, palpation is widely used to identify blood vessels, tendons or even tumors; and the knowledge on the exact location of such elements is often crucial with respect to the outcome of the intervention. This paper presents a review of the actual research directions in the field of palpation in RAMIS. Index Terms—Palpation, Surgical Robotics, Haptic Feedback, Robot-Assisted Minimally Invasive Surgery. I. I NTRODUCTION The advancements of the last few decades reshaped the face of surgical interventions radically. The technique of Minimally Invasive Surgery (MIS) started a revolution, when operating through small incisions using so-called laparoscopic instru- ments, while the visual feedback is provided by endoscopic cameras. This technique offered a number of benefits, such as faster recovery or lower risk of complications, and so became a standard in clinical practice across specialities. MIS also pre- sented new challenges to the surgeons, like the limited range of motion or operating in cumbersome body positions. Robot- Assisted Minimally Invasive Surgery (RAMIS) appeared to ease these difficulties; the surgeon is able to operate in a comfortable, seated position at the master console, while their motion is copied by the slave, or patient side instruments. These teleoperated systems—of whom probably the most famous is the da Vinci (Intuitive Surgical Inc., Sunnyvale, CA)—offer enhanced vision and dexterity alongside superior ergonomy [1], [2]. In the case of traditional, open surgical practice, manual pal- pation is frequently used to gain information about the deeper, non-visible layers of soft tissue. This way the surgeon can identify anatomies with different stiffness to the surroundings, like nerves, blood vessels and tumors as well, since cancerous tissue is usually harder than its environment. In MIS, tissue stiffness is commonly investigated using a procedure called instrument palpation—the tissue is palpated by a long instru- ment through the trocar, however this technique is less accurate and less sensitive than manual palpation [3]. Unfortunately, most of the current RAMIS systems still lack the ability of force sensing and haptic feedback, thus instrument palpation is infeasible. II. METHODS In this review, we followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) [4]. To find relevant publications in the field of haptics and palpation in RAMIS, the databases PubMed and Google Scholar were used. Since this paper focuses mainly on palpation in RAMIS, the area of haptic feedback is only briefly addressed. Dur- ing the search procedure the keywords ’palpation’, ’surgery’, ’stiffness’, ’feedback’, ’sensor’ and ’autonomous’ were used together. After the analysis according to PRISMA (Fig. 1.), 35 relevant studies remained from the area of palpation, those are organized into Table I, with the following columns: • ’Force sensing method’: force sensing techniques are divided to thee categories: direct, indirect and vision- based • ’Platform’: the robotic platform the project based on; • ’Key aspect of the study’: brief description of the results; • ’Form of evaluation’: the method used to validate the results; • ’Year’: the year the paper was published; • ’Ref.’: reference to the paper; The spatial distribution of RAMIS palpation research is overviewed on a map (Fig. 2.), alongside the current da Vinci Research Kit (DVRK) locations [5]. III. HAPTIC FEEDBACK In the human body, at least six types of receptors are reliable for haptic sensation. Basically, all of these are measuring force induced deformations, and can be divided into two groups; tactile and kinaesthetic sensors. Tactile receptors are sensible to higher frequencies, and located in the skin, with varying density all over the body, e.g., the skin on the fingers is quite rich in those. In contrast, kinaesthetic receptors are located mostly in muscles, joints and tendons, and are sensible in a lower dynamic range [6]. Haptic feedback could be useful in a number of manners during RAMIS interventions. However, neither the da Vinci, neither the vast majority of other commercialized RAMIS systems possesses this function. Surgeons might benefit from SACI 2019 • IEEE 13th International Symposium on Applied Computational Intelligence and Informatics • May 29-31 • Timişoara, Romania 978-1-7281-0686-1/19/$31.00 ©2019 IEEE 000099