
13
N. HOTTA ET AL.
numerous reports on the usefulness of percutaneous con-
trast echo with Levovist in the detection and differential
diagnosis of hepatic tumors and in the evaluation of
therapeutic effects.[10-12] This is a noninvasive method
and can be applied to patients with impaired renal func-
tion or those who are allergic to the contrast agents that
are used in dynamic CT, X-ray angiography, or MRI.
One disadvantage is that this method cannot visualize
tumors located 10 cm or more from the liver surface be-
cause the acoustic pressure does not increase. In the pre-
sent study, none of the target tumors were located 10 cm
or more from the liver surface, and evaluation of the
therapeutic effect was successfully performed in all cases.
In evaluating the therapeutic effect of RFA, determining
the presence or absence of residual tumor is the main
objective. If an area showing blood flow in the pre-
treatment contrast echo study appears as an avascular
area in the post-treatment contrast echo study, the tumor
is judged to be necrotic. This method is also able to de-
tect residual small blood flow that may not be detectable
by CT. Even for the nodule that was located near the
gallbladder and for which the distance between the nod-
ule and the gallbladder could not be measured accurately
by CT or plain US, the use of ultrasound contrast agent
permitted the distance to be measured more accurately
and RFA treatment to be performed more safely. One
limitation is that the ultrasound contrast agent currently
available clinically in Japan is effective for only a short
time after injection. It is expected that this limitation will
be overcome with the development of new contrast
agents.[13]
5. Conclusions
The convex puncture probe PVT-350BTP permits per-
cutaneous RFA to be performed safely and effectively.
6. References
[1] G. Francica and G. Marone, “Ultrasound-Guided Percu-
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[2] T. Livraghi, N. Goldberg, S. Lazzaroni, et al., “Hepato-
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[3] S. Ross, M. Di Stasi, E. Buscarini, et al., “Percutaneous
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[4] N. Hotta, T. Maeno, M. Ayada, et al., “Four-Dimensional
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[5] N. Hotta, T. Tagaya, T. Maeno, et al., “Advanced Dy-
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[8] N. Hotta, M. Ayda, E. Matsumoto, et al., “Usefulness of
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[9] Y. Matsuda and I. Yabuuchi, “Hepatic Tumors: US Con-
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[10] S. R. Wilson, P. N. Burns, D. Muradali, et al., “Harmonic
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[11] K. Numata, K. Tanaka, T. Kiba, et al., “Contrast- En-
hanced, Wide-Band Harmonic Gray Scale Imaging of
Hepatocellular Carcinoma: Correlation with Helical
Computed Tomographic Findings,” Journal of Ultra-
sound in Medicine, Vol. 20, No. 2, 2001, pp. 89-98.
[12] N. Hotta, T. Tagaya, T. Maeno, et al., “Usefulness of
Contrast-Enhanced Ultrasonography with Dynamic Flow
Imaging to Evaluate Therapeutic Effects for Hepatocel-
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[13] S. R. Wilson and P. N. Burns, “An Algorithm for the
Diagnosis of Focal Liver Masses Using Microbubble
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1401-1412. doi:10.2214/AJR.04.1920
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