Breast Magnetic Resonance Imaging - Essay Example

? Breast Magnetic Resonance Imaging Insert (s) Breast Magnetic Resonance Introduction Breast Magnetic Resonance Imaging (MRI) is one of the non-invasive medical procedures that is increasingly being used in the diagnosis and treatment of breast cancer. Magnetic resonance Imaging involves the use of powerful magnetic fields and radio frequencies to produce computerized and detailed images of soft tissues, organs and bones, as well as any other internal body structure. Unlike some imaging techniques, such as X-ray or computed tomography, MRI does not require the use of ionizing radiation. Despite recent advances, MR imaging still has a number of limitations particularly with regard to its specificity and sensitivity. Breast Magnetic Resonance Imaging is, nevertheless, an important diagnostic tool for the evaluation, identification and monitoring of breast tumour (Schnall, 2006, p. 48). 1. Discuss the hormonal influences on breast tissue during the normal menstrual cycle. Why is this important when scheduling a breast MRI? In normal premenopausal women, breast tissues often undergo significant changes, particularly in their structures, density, protein expression, as well as cellular functions, which correspond to the various phases of menstrual cycle. Consequently there is a number of changes in the breast tissue which are attributed to hormonal influences during the normal menstrual cycles. Breast tissues are generally sensitive to the hormones, such as sex hormones like progesterone, oestrogen, follicular stimulating hormone and luteal hormones that are normally produced during menstrual cycles. Rosen (2001, p.123) argues that the breast tissue changes are primarily caused by hormonal influences are associated with the four phases of menstrual cycle. Hormonal fluctuations which occur during the menstrual cycle affect the uptake of gadolinium in the breast tissues thereby reducing the sensitivity of imaging. During the first few days of menstrual cycle, the hormonal changes cause regression of the breast tissues, which is characterized by the presence of inflammatory infiltrate, atrophy of myopithelium and condensation of interlobular stroma. On the other hand, the later half of the menstrual cycle is often associated with alveolar budding, stromal edema and increased breast secretions. These changes are attributed to the cumulative effects of the sex hormones produced during menstrual cycle. According to Battersby and King (1992, p. 603), it is important to understand the changes in the breast tissues during menstrual cycle when scheduling breast resonance imaging because some changes, such as increased breast density, may determine impact on the accuracy of mammographic tests. For example, reduced breast tissue density is associated with the follicular phase of menstrual cycle while increased breast density is common in the luteal phase (See figure 1). Although not all magnetic resonance examinations undertaken during luteal phase of the menstrual cycle may be necessarily difficult to interpret, the results of the tests are usually having false positive findings which are a challenge to their interpretation. Fig.1 Breast magnetic resonance image during the follicular phase of the menstrual cycle To improve the accuracy of mammography, scheduling of breast magnetic resonance imaging should be done during the follicular phase (1st and 2nd week) as opposed to during the luteal phase (3rd and 4th week). Vihko (1994, p. 233) suggests that this is because progesterone hormones are at their lowest during the follicular phase, making it the most optimum period for magnetic resonance imaging. Generally, the breast structure changes that occur during the menstrual cycle due to high levels of progesterone in the luteal phase not only reduce the sensitivity of breast MRI but also the specificity of the mammographic findings. 2. Discuss the BRCA 1 and BRCA 2 genes. What are the implications for a patient who has a harmful BRCA gene mutation, and how are such patients managed clinically? BRCA1 and BRCA2 are human genes found in chromosome 17(as shown in figure 2) and commonly classified as tumour suppressors because they help in the manufacture of proteins that protect cells from tumours and uncontrolled growth. In normal human cells, BRCA1 and BRCA2 are responsible for the stability of the cell DNA, as well as prevention of uncontrolled growth of cells (Tutt, 2002, p. 574). The two BRCA genes also help repair damages in the breast cells and maintain their normal growth. In some individuals, however, the BRCA genes may contain hereditary mutations and abnormalities. Although there are a number of similarities in the functions of the two genes, a few differences also exist. For example, women with BRCA1 mutations generally have higher risks of developing breast and ovarian cancers than their counterparts having BRCA 2 mutations. Additionally, BRCA1 is often associated with breast cancers which do not usually unresponsive to drugs and hormones and appear earlier than normal while BRCA2 are closely liked with post menopausal breast cancers which respond well to hormones (Kadouri et al., 2007, p. 468). Figure 2. Location of BRCA1 gene on the human chromosome Sources: http://gslc.genetics.utah.edu/units/newborn/images/BRCA12 The mutation of these two genes is mostly linked with the occurrence of hereditary breast cancer and other related tumours. Harmful mutations are liked with uncontrolled cell growth because they hinder the production of tumour suppressing proteins making it easier the body more susceptible to tumour and cancer development. Mutations of BRCA genes are often passed from parents to their offspring regardless of the sex of the children and therefore each child born to parents with BRCA gene abnormalities or harmful mutations have approximately 50% chance of inheriting the mutant genes from their career parents (Robson, 2007, p. 154). There are a number of serious health implications for patients who are diagnosed with the harmful BRCA gene mutation. This is particularly because the harmful mutations of BRCA1 and BRCA2 mutations often results in increased risk of breast cancer development even at an early age before menopause. Thompson (2002, p. 1358) also concurs that harmful BRCA1 mutations have generally associated with increased risks of tumours, such as cervical pancreatic, uterine and colon cancer in women. Men with BRCA1 harmful mutations are also likely to develop early prostate cancer, breast cancer and testicular cancer. On the other hand, BRCA2 abnormalities and mutations in men are often responsible for increased risks of melanoma, pancreatic, bile duct and gall bladder cancer. MRI and other diagnostic procedures can effectively be used in the patients who are carriers of mutant genes to access the level of their predisposition to cancer, as well as determine the appropriate steps needed to be performed to reduce their chances of developing cancer. It is, however, important to note that not all cases diagnosed with BRCA1 and BRCA2 abnormalities may lead to breast cancer as some mutations are relatively harmless. There are also a number of people who develop breast cancers without any family history of the disease or abnormal BRCA genes. Tutt (2002, p. 573) argues that BRCA1 and BRCA2 mutation and abnormalities are more likely to be detected in people whose blood relatives have been diagnosed with breast cancer and such individuals also have increased risk of developing other complications, such as ovarian, pancreatic as throat cancer, as well as melanoma. When a patient is diagnosed with or is suspected to have the harmful BRCA mutations, a number of management strategies can be used to prevent or detect the potential development of cancer in the affected individuals. According to Thompson (2000, p. 1361), some of the common clinical steps that are often taken to help such patients cope up with their conditions include carrying out regular screening, performing protective surgery, chemotherapy and the use of hormonal therapy medicines. First and foremost, women diagnosed with deleterious BRCA mutations require intensive and frequent screening tests using a number of techniques, such as Breast magnetic resonance imaging (MRI), ultrasonography, CT scans and X-ray. Although mammography does not prevent the development of cancer, regular cancer screening is particularly important because it allows early detection of cancerous tissues consequently making it easier to prevent their spread. Another clinical management strategy that is commonly used in patients with abnormal BRCA1 or BRCA2 genes is carrying out prophylactic surgery to remove the breast tissues to reduce the likelihood of cancer development. Removal of the breast tissues can significantly minimize the risk of breast cancer by up to nearly 90% (Robson, 2007, p. 147). In women who have been diagnosed with invasive breast cancer, both breasts may be removed. Protective surgery is particularly effective is the procedure is performed during the early stages of cancer. After the surgery, breast reconstruction is often done by plastic surgeons. Generally, protective surgeries have greater benefits to younger patients since older patients are more likely to develop medical complications, such as heart disease and diabetes after the surgery. Hormone replacement is another important clinical therapy that can be used in women with BRCA gene mutations to reduce the risk of developing cancer (Schnall, et al. 2006, p. 43). For example, a combination of progesterone and oestrogen may be used in both premenopausal and postmenopausal women. Lastly, chemotherapy can also be used to reduce cancer risks in patients diagnosed with BRCA gene abnormalities. Chemoprevention of cancer development generally involves the use of medicines such as tamoxifen to help reduce the cancer risk in patients with BRCA gene mutations. For instance women who have been diagnosed with the harmful BRCA1 or BCRA2 gene mutations but have not developed breast cancer may be given such drugs to disease their risks of developing the disease. This is particularly effective when used in preventing the first breast cancer case in the patient. For example, some drugs such as Aromatase inhibitors are usually used to reduce the production of oestrogen in premenopausal women and this consequently limits their risks of developing cancer (Robson, 2007, p. 150) 3. MRI can be used to assess breast implant integrity. Discuss intracapsular and extra capsular rupture and their MRI appearances Magnetic resonance imaging is increasingly playing a significant role in the assessment and determination of breast plant integrity. For example, MRI can effectively be used to diagnose and illustrate breast implant ruptures with more accuracy as compared to the other imaging techniques such as mammography and ultrasound. Because of the high contrast and spatial resolution between the soft tissues (as seen in figure 3 below), magnetic resonance imaging is currently one of the most important imaging modalities used in the assessment of breast implant. MRI also has the highest specificity and sensitivity when used to detect potential implant ruptures (Narisada et al., 2006, p. 298). Lastly, MRI can effectively identify and differentiate intracapsular and extra capsular ruptures as well as assess granuloma formation and the level of silicone leakage into the parenchyma of the breasts. Fig. 3 Magnetic resonance image of breast implants Source: (Silver, 2002, p. 803). There are two major types of breast implant ruptures namely intracapsular and the extra capsular ruptures. Generally, intracapsular rupture refers to the case where all the gel or some of it manage to leak beyond the implant’s silicone shell but does not go past the fibrous capture that usually forms around it. On the other hand, extra capsular rupture is the rupture of free silicone gel implants which escapes into the breast tissues through the capsule. In some situations, the escaping gel may find its way to the lymph nodes (Silver, 2002, p. 803). MRI diagnosis can be effectively used to assess the leakage of implants so that the ruptured shell and leaked silicone can be replaced. Since the resonance of fats is similar to that of silicone, the MRI images of the silicone implants often appear similar or water suppressed images (as shown in figure 4 below). During the assessment of the breast implant integrity, MRI high resolution images of the implants are generally achieved by exploiting the resonance frequency differences in fat, silicone and water. For example, resonance frequency of water is 320Hz higher than that of silicone as shown in Figure 5. Figure4. Image showing MRI's ability to differentiate fat, water and silicone breast implants Fig 5.Table showing the appearance of Silicone breast implants, Water and Fat on MRI. MRI Pulse Sequence Silicone Fat Water FSE T2 weighted Bright Moderate Very bright FSE T2 weighted, water suppressed Bright Moderate Dark Magnetic resonance images of intracapsular rupture often appears as keyhole signs which generally indicate the presence of silicone in and out of the radial fold. The images also contain linguine which refers to folded and collapsed elastomeric shell floating in the silicone gel. This is one of the most reliable indications of the presence of intracapsular rupture. According to Lipworth (2004, p. 285), extra capsular rupture images usually appear as macroscopic extrusions in the fibrous capsule, as well as in the surrounding muscles. References Battersby, R. & King, A. 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Robson, O. “Management of an Inherited Predisposition to Breast Cancer.” NEJM, 8(7), p. 147- 154. 2007. Schnall, B. et al. “Diagnostic Architectural and Dynamic Features at Breast MR Imaging: Multicenter Study.” Radiology. 238(1), p. 42–53. 2006. Silver, H. “Reduction of Capsular Contracture with Two-stage Augmentation Mammaplasty and Pulsed Electromagnetic Energy.” Plastic Reconstructive Surgery 69(5), p.802-805. 2002. Thompson , E.G. “The Breast Cancer Linkage Consortium. Cancer Incidence in BRCA1 Mutation Carriers.” Journal of the National Cancer Institute, 94(18), 1358–1365. 2002. Tutt, A. “The Relationship between the Roles of BRCA Genes in DNA Repair and Cancer Predisposition.” Trends Mol Med 8(12), p. 571-576. 2002. Rosen, P. P. Rosen's Breast Pathology. Philadelphia: Lippincott Williams & Wilkins. 2001. Vihko, A. “Endocrine Characteristics of Adolescent Menstrual Cycles: Impact of Early Menarche.” J Steroid Biochem, 20(4), p. 231-236. 1994. Read More