Neutron capture therapy with gadopentetate dimeglumine: experiments on tumor-bearing rats.
OBJECTIVE
The therapeutic effect of neutron capture therapy with the gadolinium (Gd) complex gadopentetate dimeglumine was studied in vivo in rats using a beam of thermal neutrons.


METHODS
Rats with Jensen sarcomas 10-15 mm in diameter in their right thigh were irradiated with a thermal neutron beam that had fluences of 3.6 x 10(11) (20 min) or 5.4 x 10(11) n/cm2 (30 min) in the absence and presence of 5,500 or 13,750 ppm gadopentetate dimeglumine. Gadopentetate dimeglumine was administered directly into the tumor prior to neutron irradiation. Four groups of rats were studied: two groups of nonirradiated controls (Gd-n- and Gd+n-) and two irradiated groups (Gd-n+ and Gd+n+). In the follow-up period, we measured the subjects' clinical status and tumor size as a function of time postirradiation.


RESULTS
In both control groups (Gd-n- and Gd+n-), the tumor progressively grew. Pure irradiation by thermal neutrons in the Gd-n+ group resulted in a transient inhibition of tumor growth with total regressions of 15%. Intratumoral administration of 13,750 ppm gadolinium per gram of tumor and subsequent neutron irradiation (the Gd+n+ group; fluence = 3.6.10(11) n/cm2) significantly increased the tumoricidal effects (i.e., decrease of tumor growth up to a complete regression of the tumors in about 80%). Treatment-specific differences between the groups were confirmed by histologic observations.


CONCLUSIONS
The intratumoral administration of the hydrophilic magnetic resonance imaging contrast medium gadopentetate dimeglumine prior to irradiation with thermal neutrons leads to a therapeutic gain (i.e., reduction) on experimental Jensen sarcomas.
Khokhlov
V F
VF
Institute of Biophysics, Ministry of Public Health of Russia, Moscow, Russia.
Yashkin
P N
PN
Silin
D I
DI
Djorova
E S
ES
Lawaczeck
R
R
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000528:radiation effects / Q000627:therapeutic use*; D004195:Disease Models, Animal; D018450:Disease Progression; D004307:Dose-Response Relationship, Radiation; D005500:Follow-Up Studies; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000528:radiation effects / Q000627:therapeutic use*; D015552:Injections, Intralesional; D008297:Male; D009368:Neoplasm Transplantation; D017247:Neutron Capture Therapy; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012513:Sarcoma, Experimental / Q000473:pathology / Q000532:radiotherapy*; D016896:Treatment Outcome
D003287:Contrast Media; D019786:Gadolinium DTPA