Retraction by surface ferromagnetisation of target tissues: preliminary studies on feasibility of magnetic retraction for endoscopic surgery.
BACKGROUND
Magnetic retraction has potential advantages over existing direct physical retraction means (e.g., forceps) in terms of providing complete atraumatic retraction, avoiding tumour cell exfoliation as well as offering the possibility of noncontact retraction. This paper describes a pilot study of surface magnetic retraction of the gastric mucosa to facilitate resection.


METHODS
Fifteen porcine stomach specimens were used in this pilot study. The uniaxial tensile properties of retracted mucosa were initially studied using a tensiometer. Magnetic media of ferromagnetic microparticles (stainless steel 410) dispersed in cyanoacrylate liquid were prepared at four different concentrations, and a neodymium permanent magnet was used to magnetically retract the media. The media was finally surface-glued to the target mucosa for performing a simulated surgical procedure.


RESULTS
The force measurement data show that the retraction forces increased as the concentrations of microparticles and magnetic media volumes increased. A magnetic media concentration of 2 g/mL was most suitable since it offered sufficient retraction force from a small volume of applied media, e.g., the observed magnetic forces exerted on 50 microL of media were 1.42 N by a 3-mm magnet and 3.75 N by a 6-mm magnet, respectively, both being more than sufficient for the mucosal retraction. The additional forces required for dissection with four alternative instruments, i.e., electrosurgery hook, snares, scalpel or scissors, were also measured, e.g., the total force required to retract up to 10 mm and resect the mucosa with snares was 0.36 +/- 0.17 N. In a simulated surgical procedure (resection of gastric mucosa with glued magnetic medium) retraction by the magnet allowed resection of the tented mucosa by an electrosurgical snare.


CONCLUSIONS
Surface ferromagnetisation of target mucosal tissues could enable magnetic retraction for endoscopic surgery.
Wang
Zhigang
Z
Institute for Medical Science and Technology, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK.
Wang
Lijun
L
Tang
Benjie
B
Frank
Timothy
T
Brown
Stuart
S
Cuschieri
Alfred
A
D000818:Animals; D004210:Dissection / Q000295:instrumentation; D004598:Electrosurgery / Q000295:instrumentation; D004724:Endoscopy / Q000379:methods*; D005240:Feasibility Studies; D005753:Gastric Mucosa; D066298:In Vitro Techniques; D058085:Iron Compounds; D008280:Magnetics; D010316:Particle Size; D010865:Pilot Projects; D013193:Stainless Steel; D013525:Surgical Instruments; D013552:Swine
D058085:Iron Compounds; D013193:Stainless Steel