A smart endoscopic ultrasound needle call for life

Phones are linked to life in many ways, from keeping in touch with friends, relatives, and colleagues to calling for help in case of danger. In an extreme context, the last phone call is the ultimate appeal to life before the execution of a death sentence.

On the other hand, phones are usually regarded as distracting and annoying in endoscopy suites. Patients are usually discouraged from using their phones in restricted-access hospital areas and doctors may appear unprofessional when using phones during their working activity. Our colleagues from the University of Medicine and Pharmacy of Bucharest have a different opinion: we should instead keep our phones on and have them wirelessly connected to an endoscopic ultrasound (EUS) needle while performing tissue acquisition.

In this issue of Endoscopy, Ciocîrlan et al. report the results of a prospective trial using a digital accelerometer, which was taped onto an EUS fine needle (EZShot3 plus, 22G; Olympus Corp.) and connected via Bluetooth to the physician’s smartphone [1]. A dedicated app was available to trace and show the speed of needle insertion into solid pancreatic tumors of more than 20 mm in size. The authors performed one slow needle pass (slower than 9.8 m/sec²) and one fast needle pass (faster than 9.8 m/sec²) in each lesion in a random order, fanning the needle 10–15 times inside the lesions on both passes. The study group consisted of 51 patients harboring solid pancreatic lesions (mean size 40 mm) equally distributed among the head, body, and tail.

“...the fast sampling technique monitored by a digital accelerometer could be useful for training as it represents a cheap and easy method for self-evaluating an endosonographer’s ability to maneuver the needle within a defined lesion.”

What was the outcome? The faster the better. The fast needle passes yielded more Papanicolaou IV (neoplastic: benign and other), V (suspicious for malignancy), and VI (malignant) specimens than the slow passes, increasing the overall diagnostic accuracy from 69 % to 84 % (P = 0.02). Moreover, sample quality was greatly improved with the fast passes as opposed to the slow ones (94 % vs. 77 %; P = 0.007).

A previous Japanese investigation on the same topic failed to show any significant advantage when introducing the needle into solid pancreatic lesions with a quick thrust, the so-called “door-knocking method” [2]. However, the authors may have knocked with the wrong hand as they used a standard 22G cobalt–chrome cytology fine needle. In contrast, the needle used in the Romanian study is certified for histology, thanks to the Menghini-type sharp cutting tip, and is made of nitinol that retains its shape without any deformation after multiple passes. It is plausible that a sharper and more compliant needle (cobalt–chrome alloys, when compared with nitinol alloys, possess more stiffness, which is the opposite of compliance) is more suitable for the hard work of quickly and repeatedly puncturing solid pancreatic lesions.

Interestingly, somewhat similar findings were reported using ex vivo equipment to study the cutting of soft tissue with a surgical scalpel in pig livers [3]. Interaction forces at cutting speeds ranging from 0.1 cm/sec to 2.54 cm/sec were measured. The experimentally measured force-displacement curves revealed that the liver cutting consisted of a sequence of repeated phases of linear deformation followed by a crack growth phase. The deformation resistance of the tissue during each cutting phase was measured in the form of a self-consistent local effective Young’s modulus. Results at different cutting speeds showed that the tissue resistance to deformation decreased as the cutting speed increased, in some ways resembling the findings obtained with each EUS needle movement within solid pancreatic tumors in the Romanian study.

This study adds to the dense population of different methods, devices, and techniques of EUS fine needle sampling that already exist, including with/without the use of a stylet, slow pull/wet/dry/no suction, needle tip design either for cytology or for histology, and specimen expression, evaluation, and fixation [4] [5] [6] [7] [8]. However, it should be noted that only per-protocol lesions > 20 mm in diameter were included. It is likely that the fast pass technique may be less suitable for smaller lesions.

Additionally, the fast sampling technique monitored by a digital accelerometer could also be useful for training as it represents a cheap and easy method for self-evaluating an endosonographer’s ability to maneuver the needle within a defined lesion. In this respect, smart EUS needles may turn out to be more convenient for beginners when learning the correct sampling technique than for regular use by experienced endosonographers. The latter have had it in their cords since the beginning of their EUS practice that you should slowly withdraw and quickly advance the needle when sampling a solid lesion. If they are seen doing the opposite, they might be using a reverse-bevel histology needle, but this is the only exception to the rule.

Publication History

Article published online:
26 August 2021

• References

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