Positron emission mammography (PEM) is a nuclear medicine imaging modality used to detect or characterise breast cancer.[1]Mammography typically refers to x-ray imaging of the breast, while PEM uses an injected positron emitting isotope and a dedicated scanner to locate breast tumors. Scintimammography is another nuclear medicine breast imaging technique, however it is performed using a gamma camera. Breasts can be imaged on standard whole-body PET scanners, however dedicated PEM scanners offer advantages including improved resolution.[2][3]
PEM is not recommended for routine use or for breast cancer screening, in part due to higher radiation dose compared to other modalities.[4] Compared to breast MRI, PEM offers higher specificity.[5] Specific indications can include "high-risk patients with masses > 2 cm or aggressive malignancy and serum tumor marker elevation".[6][7]18F-FDG is the most common radiopharmaceutical used for PEM.[8]
PEM uses a specialised scanning system. Though some systems resemble a small PET scanner with a ring of detectors, others consist of a pair of gamma radiation detectors placed above and below the breast.[citation needed] On these systems, mild breast compression is applied to spread the breast and reduce its thickness. The detection process is identical to standard PET scanners. Positrons emitted by the injected 18F-FDG annihilate on interaction with electrons in tissue, leading to the emission of a pair of photons travelling in opposite directions. The detection of two simultaneous photons indicates the emission of a positron at a point on the line linking the two detection events. An image is the reconstructed from the collected emission data.[9][10]
Mammography using positron emitters was first proposed in 1994.[11] PEM is now approved in the United States and Europe for post-diagnosis imaging, with multiple commercial systems available.[12][13]
^Marino, Maria Adele; Helbich, Thomas H.; Blandino, Alfredo; Pinker, Katja (9 June 2015). "The role of positron emission tomography in breast cancer: a short review". Memo - Magazine of European Medical Oncology. 8 (2): 130–135. doi:10.1007/s12254-015-0210-z. S2CID68723912.
^Kalles, Vasileios; Zografos, George C.; Provatopoulou, Xeni; Koulocheri, Dimitra; Gounaris, Antonia (13 December 2012). "The current status of positron emission mammography in breast cancer diagnosis". Breast Cancer. 20 (2): 123–130. doi:10.1007/s12282-012-0433-3. PMID23239242. S2CID42928316.
^Fletcher, J. W.; Djulbegovic, B.; Soares, H. P.; Siegel, B. A.; Lowe, V. J.; Lyman, G. H.; Coleman, R. E.; Wahl, R.; Paschold, J. C.; Avril, N.; Einhorn, L. H.; Suh, W. W.; Samson, D.; Delbeke, D.; Gorman, M.; Shields, A. F. (20 February 2008). "Recommendations on the Use of 18F-FDG PET in Oncology". Journal of Nuclear Medicine. 49 (3): 480–508. doi:10.2967/jnumed.107.047787. PMID18287273.
^Cintolo, Jessica Anna; Tchou, Julia; Pryma, Daniel A. (16 March 2013). "Diagnostic and prognostic application of positron emission tomography in breast imaging: emerging uses and the role of PET in monitoring treatment response". Breast Cancer Research and Treatment. 138 (2): 331–346. doi:10.1007/s10549-013-2451-z. PMID23504108. S2CID21975083.