The labelling of Nanocoll® with [111In] for dual-isotope scanning

Alpha-particle-induced reactions on natural silver in the 10-50 MeV energy range: Production of 111In, 110mIn and 109Cd

Production cross sections of medical radionuclides 111In, 110mIn and 109Cd were investigated in the α-particle-induced reactions on natural silver up to 50 MeV. The stacked-foil activation technique and γ-ray spectrometry were used to determine the cross sections. The excitation functions of byproducts 104g,105,106m,110mAg, 107,111mCd and 107g,108g,108m,109,110gIn were also determined. Physical yields of 111In, 110mIn and 109Cd were deduced based on the measured cross sections.

Axillary lymph node drainage pathways from intradermal and intraparenchymal breast planes

BACKGROUND

To compare functional anatomy of breast peri-areolar and peri-tumoral lymphatic drainage basins.

METHODS

Fifteen breast cancer patients received simultaneous peri-areolar (intradermal) and peri-tumoral (intraparenchymal) injections of human polyclonal immunoglobulin (HIG) labeled with (99m)Tc and (111)In 2 to 4 h before axillary lymph node clearance surgery. Resected nodes (range 5-20; median 16) were individually counted for (99m)Tc and (111)In in a well-counter and ranked according to activity content (echelon). Activity in distal nodes was negligible so extraction efficiency (E) of HIG in the first echelon node was calculated as counts divided by total counts in the chain.

RESULTS

Five- to 10-fold more activity was recovered after intradermal injection. The injection planes identified the same first echelon node in 10 patients (group 1) but different in five (group 2). In group 1, intradermal E correlated with intra-parenchymal E (r = 0.82; P < 0.01). E of intradermal first echelon nodes in group 2 was 51 (SD 13)%, similar to intradermal E in group 1 (58 [23]%). E of intraparenchymal first echelon nodes in group 2, however, was 28 (6)%, lower than intraparenchymal E in group 1 (54 [20]%; P < 0.02).

CONCLUSIONS

Lymph nodes extract approximately 50% of HIG. Extracted HIG does not cascade to distal nodes, validating HIG for sentinel node lymphoscintigraphy. HIG injected intradermally at the areola drains via a single route to the axilla. In two-thirds of patients, peri-tumoral HIG follows a similar route, but in one-third of patients drainage from the parenchymal plane is more complex, with more than one route to the axilla.

Dual-isotope lymphoscintigraphy using albumin nanocolloid differentially labeled with 111In and 99mTc

The aim of this study was to develop and evaluate 111In- and 99mTc-labeled derivatives of albumin nanocolloid (NC) for dual-label lymphoscintigraphy to allow simultaneous comparison of lymphatic flow from different tissue planes draining a tumour bed for accurate identification of sentinel lymph nodes (SLN). Using the chelator, p-isothiocyanatobenzyl-1,4,7, 10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 111In-DOTA-NC and 99mTc-DOTA-NC were compared in vitro with respect to stability of labeling, colloidal status and particle size, then in vivo by measuring their clearance rates from a subcutaneous injection depot. 111In-DOTA-NC and 99mTc-DOTA-NC were indistinguishable on the basis of in vitro criteria. Their in vivo clearance rates, however, were disparate (0.0015 to 0.075 min(-1) for 111In and 0.0072 to 0.067 min(-1) for 99mTc), 111In being faster in three studies and markedly slower in three. This demonstrates that even when dual-labeled radiotracers behave identically in vitro, they will not necessarily do so in vivo. Further work is needed to develop dual-labeled NC.