Molecular Breast Imaging (MBI) is a highly sensitive and specific radiological exam which relies on functional imaging technology. The examination and study procedure is simple, safe and fast. The patient receives a very small injection of a commonly used radiotracer. The tracer has a higher rate of uptake in cancerous lesions due to mitochondrial activity in the cells, which shows up clearly on the image as a ‘hot spot’. Due to the specific pharmacokinetics of the tracer, the patient can be immediately positioned on the LumaGEM® Molecular Breast Imaging system. The patient is positioned in the system in the same manner as she would with standard X-ray mammography with minimal compression. Typically, two image views are taken, cranial cauda (CC) and mediolateral oblique sections (MLO). Each view takes between 10-20 minutes depending on dose of radiotracer used (4-8 mCi is typical used clinically).1 The image is processed immediately and can be read by the radiologist within seconds alongside the patient’s annual mammography images.
The sample images below compare a patient’s Gamma Medica LumaGEM MBI image with a mammogram which that was initially read as negative for cancer:
Unlike mammography, tomosynthesis and ultrasound, all of which are anatomical imaging tests, molecular breast imaging is a functional imaging modality that highlights metabolic activity in the breast regardless of tissue density; as density and cancer often appear the same on a mammogram and 3D mammography (tomosynthesis). This makes it extremely difficult to distinguish between the two. Studies have shown that mammograms fail to detect cancers in one-third to one-half of women with dense breast tissue.2
Dense breast tissue is a serious concern and there is a growing awareness of the limitations of mammography screening for women with dense breast tissue. As such, the urgent need for an effective adjunct screening technology led to the creation of Molecular Breast Imaging.
As a secondary diagnostic tool, MBI has distinct advantages over ultrasound, MRI and 3D mammography (tomosynthesis):
- Ultrasound uses anatomical imaging technology and is operator dependent; this results in a high number of false positive and unnecessary biopsies in women who have dense breast tissue. Additionally, by virtue of its technology, Automated Whole Breast Ultrasound has inherently low sensitivity and increased false positive findings.3
- MRI is very overly sensitive and indiscriminate. While adding MRI as a secondary screening procedure to the initial mammogram may result in a higher cancer detection rate, the number of false positive biopsies are also significantly increased.3 Additionally, many women are not candidates for MRIs due to pacemakers or other ferromagnetic implants, or due to poor renal function, claustrophobia, and body size or gadolinium allergies.
- Tomosynthesis (also known as “3D” Mammography) may provide slightly higher specificity when compared to mammography (64% vs 60%); however, neither approach the specificity rates associated with MBI or MRI.4 The specificity with MBI is reported to be as high as 93% following a mammogram.5
- Swanson T, Tran T, Hruska C, Rhodes D, & O’Connor M. Patient acceptance of half-dose vs half-time molecular breast imaging. Journal of Nuclear Medicine, 2015:56(supplement 3), 2634-2634.
- Kolb TM, Lichy J, Newhouse JH. Comparison of the performance of screening mammography, physical examination, and breast US and evaluation of factors that influence them: an analysis of 27,825 patient evaluations. Radiology. 2002;225(1):165–175.
- Berg WA, Zhang Z, Lehrer D, et al. Detection of Breast Cancer With Addition of Annual Screening Ultrasound or a Single Screening MRI to Mammography in Women With Elevated Breast Cancer Risk. JAMA, April 4, 2012—Vol 307, No. 13
- Gur D, Abrams GS, Chough DM, et al. Digital breast tomosynthesis: observer performance study. AJR. 2009; 193:586-591
- Boyd NF, Dite GS, Stone J, et al. Heritability of mammographic density, a risk factor for breast cancer. NEJM. 347:886-894.