NEUROENDOCRINE TUMORS
Guest Editors: Bombardieri E. 

The Quarterly Journal of Nuclear Medicine 2000 March;44(1):59-67

Copyright © 2009 EDIZIONI MINERVA MEDICA

lingua: Inglese

Intraoperative use of gamma-detecting probes to localize neuroendocrine tumors

Adams S., Baum R. P.

From the Department of Nuclear Medicine Johann Wolfgang Goethe University Medical Center Frankfurt/Main, Germany *Clinic of Nuclear Medicine/PET Center Zentralklinik Bad Berka GmbH, Bad Berka, Germany

Neuroendocrine ­tumors are char­ac­ter­ized by the expres­sion of dif­fer­ent pep­tides and bio­gen­ic ­amines. These ­rare ­tumors ­tend to ­grow slow­ly and are noto­ri­ous­ly dif­fi­cult to local­ize, at ­least in the ear­ly stag­es. Surgical remov­al is the ­only defin­i­tive ther­a­peu­tic ­option for neu­ro­en­do­crine ­tumors and ­relief ­from hyper­func­tion­al stat­us. The effec­tive­ness of sur­gi­cal treat­ment is invar­i­ably depen­dent ­upon the com­plete sur­gi­cal exci­sion of all ­tumor tis­sue, ­because micro­scop­ic and ­occult dis­ease not read­i­ly ­seen by the sur­geon may ­remain in ­situ, lead­ing to short­ened sur­vi­val. Therefore, pre- and intra­op­er­a­tive local­iza­tion of the pri­mary as ­well as of met­a­stat­ic ­tumors is of ­utmost impor­tance. Radioguided sur­gery (RGS) is an intra­op­er­a­tive tech­nique ­that ­enables the sur­geon to local­ize radio­lab­elled tis­sue ­based on the char­ac­ter­is­tics of the var­i­ous tis­sues. Concerning gas­troen­te­rop­an­creat­ic ­tumors (GEP), intra­op­er­a­tive gam­ma ­probe exam­ina­tion is ­able to ­reveal ­small ­tumor ­sites accu­mu­lat­ing (111In-­DTPA-D-Phe1)-pen­tet­re­o­tide ­more effi­cient­ly (>90%) ­than som­a­tos­ta­tin recep­tor scin­tig­ra­phy (68%-77%), ­because ­lesions ­with a ­size small­er ­than 5 mm in great­est dimen­sion ­could be iden­ti­fied. Furthermore, RGS iden­ti­fied 57% ­more ­lesions ­when com­pared to the “pal­pat­ing fin­ger” of the sur­geon. In medul­lary thy­roid can­cer (MTC), sur­gi­cal remov­al of the ­tumor is the ­first and ­most effi­cient treat­ment of the dis­ease. Persistent or increas­ing ser­um cal­cit­o­nin and car­cin­oem­bryon­ic anti­gen (CEA) lev­els ­imply ­tumor recur­rence ­after thy­roid abla­tion. For imag­ing recur­rent MTC ­many radio­phar­ma­ceu­ti­cals ­have ­been ­used to vis­u­al­ize ­tumor ­sites, but ­none of ­them has ­shown excel­lent sen­si­tiv­ity. Preoperative som­a­tos­ta­tin recep­tor scin­tig­ra­phy and intra­op­er­a­tive RGS in ­patients ­with recur­rent MTC dem­on­strate ­only ­part of the ­tumor ­sites and can­not vis­u­al­ize ­small ­tumor ­sites (less ­than 10 mm). In com­par­i­son, RGS ­using 99mTc(V)-­DMSA ­detects metas­ta­ses ­with a ­size of 5 mm in diam­e­ter, where­as the “pal­pat­ing fin­ger” of the sur­geon local­ized metas­ta­ses ­with a ­size of ­more ­than 1 cm in diam­e­ter. In ­patients ­with recur­rent MTC, intra­op­er­a­tive gam­ma ­probe exam­ina­tion is ­able to local­ize ­over 30% ­more ­tumor ­lesions ­when com­pared ­with con­ven­tion­al pre­op­er­a­tive imag­ing modal­ities and sur­gi­cal find­ings. ­MIBG scin­tig­ra­phy is the ­most sen­si­tive tech­nique for the detec­tion and stag­ing of neu­ro­blas­to­ma (sen­si­tiv­ity 92%; spec­i­fic­ity near­ly 100%). Intraoperative RGS ­with ­iodine ­labelled ­MIBG has ­been devel­oped to ­improve the def­i­ni­tion of ­tumor lim­its or to local­ize ­small, non­pal­pa­ble ­tumors. Comparison of 123I- and 125I-­labelled ­MIBG ­revealed a sen­si­tiv­ity of 91% and 92%, respec­tive­ly; the spec­i­fic­ity of 125I (85%) was sig­nif­i­cant­ly high­er ­than ­that of 123I (55%). In addi­tion to scin­tig­ra­phy of the adren­al ­glands by pre­cu­sors of adren­al hor­mones, imag­ing ­with a radio­lab­elled som­a­tos­ta­tin ana­logue is pos­sible; how­ev­er, (111In-­DTPA-D-Phe1)-pen­tet­re­o­tide is not spe­cif­ic for any adren­al dis­ease or func­tion and the rel­a­tive­ly ­high radio­lig­and accu­mu­la­tion in the kid­neys lim­it­ed the use for detec­tion of ­tumors in the ­area of the adren­al ­glands.