Læknablaðið - 15.12.1997, Side 53

LÆKNABLAÐIÐ 1997; 83
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flow to the liver increased lesion size by five
times as compared to no occlusion, when the
treatment was performed with a sapphire
probe at 3 W. In experiments without inflow
occlusion, increase of power from 3 to 5 W
resulted in a 30-40% increase in thermal dam-
age but this caused carbonisation and some-
times damage to the fibre end. Ultrasonogra-
phy was found helpful in placing the laser tip
and the temperature sensors. Ultrasonography
was, however, unable to predict lesion size
because of poorly defined hypoechoic areas or
uneven distribution of hyperechoic changes.
There was no correlation between the ultra-
sonographic lesion size and the extent of
necrosis in individual experiments.
The effect of different temperatures (43, 46
or 50°C 3 mm from the tumour margin) for 30
min, and different treatment times (10,20 or 30
min) at 46°C was studied in rats with transplan-
ted liver tumours. The treatment was locally
radical when performed at 43, 46 and 50°C for
30 min but was not radical in 2 rats (2/8 or
25%) treated for 10 min and in 2 rats (2/8 or
25%) treated for 20 min at 46°C. It appeared
that total tumour necrosis was obtained with a
temperature of 54-61°C at the tumour margin
and a treatment time of 30 min.
In a subsequent study, ILT was performed
at 46°C for 30 min on the basis of these findings
and compared with resection of the tumour-
bearing liver lobe. Two of 8 rats (2/8 or 25%)
treated with surgical excision of the tumour-
bearing liver lobe and 0 of 8 rats (0/8 or 0%)
treated with ILT had local recurrence 6 days
after treatment. However, the total number of
rats with local recurrences 6,12 or 24 days after
treatment was the same (7/24 or 29%) after
ILT and surgical excision. Viable tumour cells
were never found within the necrotic tumour
after ILT. In both groups, recurrences were
located within granulation tissue or close to it.
Vascular invasion at the boundary of the tu-
mour was a common observation. The inci-
dence and extent of intraabdominal spread was
lower in rats treated with ILT than in rats
undergoing surgical resection. The difference
in intraabdominal spread between rats treated
with ILT or liver resection may have been due
to differences in trauma or immunological
reactions.