High resolution scintigraphy and Tc Bombesin are able to guide Mammotome biopsy and to detect lymph node invasion

High-resolution (HR) gamma-ray detector 99m Tc Bombesin (99m TcBN) and 99m Tc sestamibi (99m TcSM), have been used to drive Mammotome biopsy after fusion of scintigraphic with digital X-ray images. We studied eight patients with class V microcalcifications. An HR detector with spatial resolution of 3 mm was matched with Mammotome biopsy system provided with Fisher digital X-ray device: images were fused to use the pointer indifferently on X-ray, scintigraphic and fused images. Fusion between X-ray and HR image has previously been reported. The 12 Mammotome samples/patient were weighted and counted in a well counter. Tumour/bkg (T/B) ratio was measured on HR images as well as on biopsy samples. Axilla was also explored with the portable HR device in order to diagnose node invasion. Conventional histology assessment and immunohystochemical study with anti BN receptor antibody was blindly performed on samples. All the patients studied with 99m TcSM showed T1b cancer, 99m TcBN detected one T1a and two T1b cancers. HR scan of axilla detected node metastases in two patients, both studied with 99m TcBN. All the biopsies showed cancer on at least one of the 12 samples. Histology found node metastases in three patients: the two 99m TcBN positive and one studied with 99m TcSM whose axilla was negative at HR scan. Samples showed T/B ratio of 6.6±0.4 for 99m TcSM and 11.3±0.9 for 99m TcBN (p <0.01). Note that also the patient with T1a cancer, showing 10.4 T/B ratio was included in the 99m TcBN series. Not only 99m TcBN HR is able to show breast cancer and to guide biopsy, but also detects node metastases. Our is the first ex vivo measurement of T/B ratio of 99m TcBN on humans.