PMC4565575_01
Treatment plan for parotid metastasis (No.1). The upper row (A-C) shows the 3-D model with the bone (white), tumor (yellow), blood vessels (red), and electrodes (black) shown for clarity. Lower row (D-F) shows the electric field strength according to the treatment plan. Blue color indicates tumor covered above 400 V/cm, while violet indicates normal tissue above 350 V/cm. Care was taken to ensure electrodes would avoid the major blood vessels and the bone.
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PMC4565575_01_1475-925X-14-S3-S2-1.jpg
F1
The robustness of the treatment in our case was established by creation of the safety margins as shown on Figures 1 and 2, and by appropriate coverage of the whole tumor volume with electric fields shown on Figure 3. The treatment plan and electric field distribution are shown in Figures 1 and 2 for metastasis No. 1 and No. 2, respectively.
Treatment plan for metastasis in the neck (No.2) behind the left mandibular angle. The upper row (A-C) shows the 3-D model with the bone (white), tumor (yellow), blood vessels (red), and electrodes (black). Lower row (D-F) shows the electric field strength according to the treatment plan. Blue color indicates tumor covered above 400 V/cm, while violet indicates normal tissue above 350 V/cm. Care was taken to avoid penetration of the electrodes into the blood vessels.
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PMC4565575_01_1475-925X-14-S3-S2-2.jpg
F2
The robustness of the treatment in our case was established by creation of the safety margins as shown on Figures 1 and 2, and by appropriate coverage of the whole tumor volume with electric fields shown on Figure 3. The treatment plan and electric field distribution are shown in Figures 1 and 2 for metastasis No. 1 and No. 2, respectively.
Cumulative coverage of both metastases with electric fields after each electrode pair. The graphs show the volume fraction of tumor tissue that is covered with electric field of at least the strength indicated on the horizontal axis. For visual reference, reversible and irreversible electroporation thresholds for 8 pulses of 100 micros are indicated.
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PMC4565575_01_1475-925X-14-S3-S2-3.jpg
F3
The robustness of the treatment in our case was established by creation of the safety margins as shown on Figures 1 and 2, and by appropriate coverage of the whole tumor volume with electric fields shown on Figure 3.
Treatment 3-D planning for registration and navigation (A). Navigation was used to accurately access the planned skin entry points and direction of electrodes (B). Positioning of navigation system needle and first needle electrode (C) and the final positioning of all five needle electrodes (D).
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PMC4565575_01_1475-925X-14-S3-S2-4.jpg
F4
Hence the electrodes were positioned according to plan using the virtual line, extending from the tip of the guiding instrument towards the tissue (Figure 4).
Progression of metastasis coverage with electric fields in excess of 400 V/cm for the metastasis No. 1. Each figure (A-H) shows the active electrodes, marked in Arabic numerals, of the 8 electrode pairs used with the coverage following the actual pulse delivery. The figure shows overlapping coverage in most parts of the metastasis, which ensures additional robustness of the treatment. Metastasis is marked light green, and the area exposed to an electric field higher than 400 V/cm appears red. While overlapping coverage with more pulses would eventually lead to irreversible electroporation at the electric fields delivered in this case, it should be noted that only 64 pulses were delivered in total, while typically 90 pulses per electrode pair are used in irreversible electroporation.
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PMC4565575_01_1475-925X-14-S3-S2-5.jpg
F5
Italy) (Figure 5). Immediately after the treatment of the first metastasis, the electrodes were repositioned into metastasis No. 2, which was then treated with the same treatment parameters (total of 6 minutes between the two treatments, i.e. 14 minutes after bleomycin injection).