Keywords:
Breast, Oncology, Computer applications, Nuclear medicine conventional, Mammography, SPECT, Technology assessment, Diagnostic procedure, Cost-effectiveness, Tissue characterisation, Neoplasia, Calcifications / Calculi
Authors:
D. J. Wagenaar1, J. W. Hugg1, R. A. Moats2, S. Chowdhury1, B. E. Patt1; 1Northridge, CA/US, 2Los Angeles, CA/US
DOI:
10.1594/ecr2011/C-1898
Purpose
1 – Purpose
Molecular Breast Imaging (MBI) uses a new semiconductor (CZT) imaging detector in a dual-head configuration to optimize detection of small (<1.0 cm) lesions in early stage breast cancer.
The technique involves the intravenous administration of the radiopharmaceutical 99mTc-sestamibi (MIBI),
which is the contrast agent of choice in more than 15 M nuclear cardiology studies annually worldwide. The combination of enhanced permeability and retention in neovasculature with mitochondrial metabolism produce uptake of MIBI in breast cancer lesions that is generally greater than 10:1 compared with background tissue uptake.
Because MBI detects cancers in women with radiographically dense breasts,
this new modality has been proposed for use in screening of this population that is underserved by conventional mammography (MMG) due to poor sensitivity.
Screening MBI requires an analysis of the risk/benefit associated with the study. In comparison with screening MMG,
the radiation dose from MBI is systemic,
whereas in MMG the dose is concentrated within the breast tissue. The wholebody radiation dose from MBI is well documented due to nearly 20 years of nuclear cardiology with MIBI. The proposed screening application places demands upon the MBI modality to reduce the radioactivity necessary to detect small lesions in asymptomatic women. Our analysis,
based on the NRC BEIR VII risk tables,
concluded that a factor of ~6 reduction in radioactivity is necessary in order for MBI screening benefit/risk ratio to match that of MMG. From the standard 25 mCi injection,
one must reduce the MBI injected activity to 3.5 mCi.