Acute effects of shock waves on tumors assessed by magnetic resonance imaging. Possible role of blood flow reduction.

RATIONALE AND OBJECTIVES

The effects of shock waves on experimental tumors in vivo by gadolinium(+)-DTPA-enhanced magnetic resonance imaging (MRI) are assessed.

METHODS

Two amelanotic hamster melanomas were implanted in the dorsal skin of 19 hamsters. In experiment 1 (n = 7), MRI of untreated tumors was performed before, and 5 and 15 minutes after intravenous injection of Gd(+)-DTPA. In experiment 2 (n = 12), 200 shock waves were applied on one of the implanted tumors. Magnetic resonance imaging was performed 15 minutes after treatment before, and 5 and 15 minutes after injection of Gd(+)-DTPA.

RESULTS

In experiment 1, signal intensities (SI) of untreated tumors increased after injection of Gd(+)-DTPA. In experiment 2, enhancement was significantly delayed in shock-wave-treated tumors as compared with controls. Histology of the treated tumors revealed vascular damage.

CONCLUSION

Differences in enhancement between shock-wave-treated and control tumors after injection of Gd(+)-DTPA are interpreted as the consequence of reduced and delayed accumulation of Gd(+)-DTPA in treated tumors due to shock wave induced vascular damage and reduced tumor perfusion.