Microwave ablation assisted by a computerised tomography–ultrasonography fusion imaging system for liver lesions: An ex vivo experimental study

Figures & data

Table I.  System specifications.

Module	Description
US scanner	MyLab90 Esaote
US probe	Convex array 6–2 MHz
Tracking system	PCIBirds (Ascension technology)
	Degrees of freedom: Six (position and orientation)
	Translation range, any direction: Standard transmitter = ±30 (76.2 cm)
	Angular range: All attitude
	Static accuracy standard sensor: 0.040 (1.0 mm)
	RMS position
	0.15 degree RMS orientation

Figure 1. (A) ‘Lesions’ have been localised and marked as targets. (B) The positions of all the fiduciary markers in the CT volume were identified and numbered: volume registration. (C) The external marker registration was performed by using the registration pen.

Figure 2. In two insertions we have done an accuracy evaluation, performing an insertion at high depth, of the Virtual Navigator estimation (distance between needle tip and lesion).

Figure 3. (A) Diagram of necrosis area. L-diameter, long ellipse diameter; S-diameter, short ellipse diameter; T-distance, distance from the antenna tip to the anterior margin of the ablation area. (B) Long ellipse diameter of the ablation area was measured.

Figure 4. The needle-target distance on post-procedural CT with needles in situ was measured in order to assess the accuracy of needle positioning.

Table II  The distance between target and antenna tip(T-T) in navigation and in second CT imaging.

Target	Distance T-T in navigation (cm)	Distance T-T in 2nd CT (cm)
LIVER 1
A	1.3	1.4
LIVER 2
B^a	0.3	0.3
C	1.7	1.6
LIVER 3
D^a	0.2	0.3
E	1.6	1.9
LIVER 4
F	0.6	0.4
G^a	0.1	0.4
H^a	0.2	0.4

^aThe tip of the antenna placed as close as possible to the target.