A six channel IRE generator capable of delivering a maximmum of 3000V and 50A was used (NanoKnife,AngioDynamics).
The generator could use two to six 19-gauge electrodes with adjustable exposure of the length of active tip (5-40mm). Fig. 3
To prevent ventricular arhythmia,
energy was deposited within refractory stimulating myocrdial time (ST segment of electrocardiography) by using cardiac synchronization (Accusync; Accusync Medical Research Corp.,
Milford,
Conn).
Fig. 4
IRE can be performed with CT or ultrasound guidance under general anesthesia.
To insert the electodes in the target area ,
a robotic guidance system can be used to increase the accuracy and precision.
The number of electrodes to be used depends on the shape and size of the lesion.
Tumors smaller than 2cm in diameter were treated by using three electrodes insert in a triangular configuration around the target.
Fig. 5
Each cycle consists of short pulses (90ms) of a high voltage DC (90A) with an approximate duration of 2minutes.
No precise indications of IRE have been established at the present time,
however the technique is usually performed in small solid tumors near critical structures (blood vessels) when other ablative techniques can not be used.
Main contraindications of the techique are:
- Inability to administrate general anesthesia or neuromuscular block.
- Pacemaker carriers
- Cardiac arithmias or cardiac failure.
- Coagulopathy
Follow-up was performed using CT and MR imaging
- 1 month follow up for evaluation of residual tumor or delayed complication.
- 3 and 6 months follow up to determine any recurrence.
- One year follow up for evaluation of true technical success.
In our centre IRE procedure was performed in :
- 4 patients with nolular heptocelular carcinoma(HCC),
where other ablative techniques considered contraindicated(lesion near blood vessel).
Fig. 6 Fig. 7
- 1 patient with hepatic metastasis of colorectal carcinoma Fig. 8
- 1 patient witth retroperitoneal metastasis of colorectal carcinoma
- 1 patient with pancreatic neuroendocrine tumor.
Fig. 9
- 2 patient with pancreatic adenocarcinoma not amenable to resection due to close proximity to mayor vascular structure.
In the treatment of HCC complete ablation was achieved without complication and absence of tumor viability (no nodular enanchement during arterial phase on MR image post gadolinium injection) in aproximately 12 months.
IRE was partially efective in the tratment of pancreatic lesions with tumoral progression in 6 months.
In the treatament of colorectal metastasis radiological response was good,
recording only ureteritis as the only complicacion of retropertioneal metastasis abaltions procedure.