Multimodality Approach in Breast Imaging

1.      INTRODUCTION

Worldwide breast cancer is the most common type of cancer in women.  Breast cancer is estimated to affect approximately 12.15 percent of women born today over the course of their life time and it is a common malignant disease that has been recognized since olden days (Woodworth, 2011).  However, in olden days it was rarely successfully treated due to lack of effective diagnostic tools to detect the disease at early stage (Woodworth, 2011).  Then there was mammography created and it greatly improved the odds of early detection of breast cancer and successful treatment.  The value of mammography in reducing breast cancer mortality was confirmed in early studies (Woodworth, 2011).        

Because of that, from an imaging perspective, mammography is the gold standard in the evaluation of the breast.  Breast imaging is largely indicated for detection, diagnosis, and clinical management of breast cancer (Herranz & Ruibal, 2012).  Other than mammography, ultrasound and magnetic resonance imaging (MRI) are being offered as adjuncts to the preoperative workup (Prasad & Houserkova, 2007).  Lately, other new modalities are also being offered such as positron emission tomography, 99mTc-sestamibi scintimammography, and electrical impedance tomography (EIT) (Prasad & Houserkova, 2007).  Other than that, Herranz and Ruibal (2012) introduced optical imaging as a new method also.   However, researchers noted that there is still controversy over the most appropriate use of these new modalities and issues regarding radiation doses.

            It is said that some breast imaging tests such as ultrasound, MRI, sestamibi nuclear medicine and EIT have been approved by the U.S. Food and Drug Administration (FDA) as supplements to mammography in the detection of breast cancer and other breast imaging tests like computerized thermal imaging are still undergoing clinical trials to determine whether they might be useful in detecting breast cancer (advances in mammography and other breast imaging methods, 2013).   

            To enhance diagnostic, staging, and therapeutic accuracy of breast cancer, many facilities nowadays try to accumulate a robust collection of breast imaging equipment.              

2.      BREAST IMAGING

            Imaging modalities that are commonly used to detect and diagnose breast cancer include mammography, ultrasonography, and MRI. 

2.1 Mammogram

      Types of mammograms available nowadays are screen film or analog mammography and 2D digital mammography.  A whole range of manufacturers make these machines such as GE, Bennett, Siemens, Phillips, Fischer, and Lorad.   

      For the screen film mammography, x-ray beams are captured on a film cassette.  To produce mammography films, special x-ray machines were developed exclusively for breast imaging and the image of the breast tissue is produced on a film (types of mammography, 2012).  Appendix one shows example image of screen film mammography machine.  They have a reciprocating grid to reduce scatter radiation thus avoiding fog and blurry image (introduction to breast cancer and mammography, n.d.).  The filter used is 0.03 mm molybdenum.  For mammogram, technique used is low kilo voltage peak (kVp) about 24 to 30 and milli ampere seconds (mAs) varies depending on density of breast tissue.  However when the photo timer cells are used, it provides the optimum mAs for the tissue to develop into imaged (introduction to breast cancer and mammography, n.d.).  The films used are single emulsion fast films to enhance image sharpness by eliminating geometric distortion.  Films that commonly used are Agfa, Fuji, Kodak, Konica, and Dupont.  From introduction to breast cancer and mammography (n.d.) the author noted that the screens consist of a rare earth phosphors called terbium activated gadolinium oxysulfide.  Screens have to be compatible with the film. 

      From types of mammography (2012), the author stated that in 2D digital mammography, x-ray beams are captured on a specially designed digital camera and a computer to produce an image.  Film is no longer needed with digital mammography.  Different from the screen film mammography, digital mammograms produced images that appear on the technologist’s monitor only within seconds.  Then the images are sent electronically to the radiologists to review.  The mammography machines are equipped with an image receptor connected to a computer (Bubb, 2008).  Image receptor will convert the x-ray photons into a digital picture during image acquisition and the digital images are displayed on a high resolution monitor (Bubb, 2008).  Bubb (2008) mentioned that because of the image is in digital format, physician will able to manipulate the image by enlarging it, reversing, or adjusting the contrast and brightness levels to gather more diagnostic information. 

      According to Evans and Harris (2009), American College of Radiology Imaging Network Digital Mammographic Imaging Screening Trial Study reported that digital mammography may offer a particular advantage to screen film mammography in women who are premenopausal or perimenopausal, women under the age of 50, and women with dense breasts.  More researchers reported that there is an increase in the rate of cancer detection with mammography in women with dense breasts after changing the facility from film screen to digital mammography (Evans & Harris, 2009).  Woodworth (2011) noted that recently from a study of breast cancer detection rates in 502 574 screen film mammography and 83 976 digital mammography, estimated that digital mammograms could further reduce breast cancer mortality by 4.4 percent with a concurrent 21 percent increase in over diagnosis. 

2.1.1        Advancement of Modality

            According to Levine (2013), since mammogram was first introduced, there has been significant advancement in mammographic technology.  Digital breast tomosynthesis (DBT), commonly called three dimensional (3D) mammography promises to improve breast cancer detection in young women and women with radiographically dense breast tissue (Levine, 2013).  Appendix two shows image of 3D tomosynthesis machine.  3D mammography is created because even with 2D digital mammography, the researcher metioned that approximately 15 to 20 percent of breast cancer cannot be visualized (Levine, 2013).  This is generally occurring in women with radiographically dense breast tissue.  Dense breast tissue is said can obscure an underlying cancer or can mimic a cancer when none exists.  Appendix three shows image of comparison between 2D mammogram and 3D DBT mammogram.

            During a short four seconds scan, DBT captures 15 digital projection images as it arcs over the breast.  Then these images are digitally reconstructed into a series of high resolution 1 mm slices.  After reconstructed, the images can be reviewed individually or played back in a cine loop (Levine, 2013).  Levine (2013) noted that with DBT, radiologists can examine breast tissue one layer at a time at a thickness of 1 mm.  Fine details are no longer hidden by superimposed dense breast tissue and become more visible with 3D mammography.  Recent studies shown DBT is more accurate method compared to 2D mammography for detecting early breast cancer especially in women with dense breast tissue (Levine, 2013).  From Bubb (2008), studies shows DBT was rated as superior in image quality by nearly 70 percent when compared to 2D mammography.  However, 3D mammography is still in the early adoption stages for hospitals and imaging centers (Levine, 2013).  

2.1.2        Quality Monitoring

            Quality assurance (QA) is an important part of the National Health Service breast screening program (NHSBSP) in maintaining services which meet national standards and the needs of all women invited for screening (NHSBSP, 2006).  For mammography, objectives of QA are to achieve optimum image quality, to limit radiation dose, and to minimize the number of repeat examinations (NHSBSP, 2006).  These all are QA objectives for mammographers.  The achievement of these objectives requires mammographers, medical physics services and service personnel to work closely together.  Radiographic QC procedures are the means by which this is achieved (NHSBSP, 2006).        

.           The mammographic unit is an essential component of the imaging process.  Because of that constant monitoring and maintenance is required in order to ensure best practice for care of the patient and to produce mammographic images of the highest quality for diagnostic interpretation (quality control manual, 2008).  Quality control (QC) for screen film and digital mammogram is different.  There are three aspects of the digital mammography imaging process that should be tested.  First is image acquisition which is x-ray generation and detection and flat field correction.  Second is image processing which is dynamic range adjustment, sharpening and peripheral equalization.  Third is image display which is softcopy and printed grey scale and display resolution (quality control manual, 2008).  Tests that are included in the quality control program for digital mammogram are monitor cleaning and daily checklist, laser printed sensitometry, flat field test, phantom IQ tests on acquisition station and workstation or PACS monitor, contrast to noise ratio (CNR) and modulation transfer function (MTF), automatic optimization of parameters (AOP) and signal to noise ratio checks (SNR), reading monitor calibrations, visual checks, repeat and reject analysis, view box and viewing conditions, and compression force test (quality control manual, 2008).  However, somewhat the tests may vary from unit to unit.  Those hospital that still use screen film mammography, the quality control (QC) that need to be done are establishing processor QC, daily processor QC, film crossover, fixer retention test, darkroom cleanliness, darkroom fog, viewing conditions, screen film contact, compression device test, gridlines and artifact test, x-ray equipment visual checklist, optical density stability, detail and detectability test, and repeat analysis (quality control manual, 2008).

2.2      Ultrasonography

     According to Bubb (2008) the primary role of breast ultrasonography for this many years was to evaluate areas of concern in the breast that were discovered on a mammogram or presented as a palpable abnormality during clinical breast examination or breast self examination. 

     Breast ultrasound procedures must be performed with high resolution, real time, linear array scanners (breast ultrasound accreditation program requirements, 2012).  Appendix four show images of ultrasound machines and transducers.  Superficial structures such as breasts are imaged very well by using high frequency transducers (Ballinger & Frank, 2003).  That’s why it is preferable to use transducers operating at a center frequency of at least 10 MHz for breast ultrasound and also breast ultrasound must be performed with equipment capable of electronic focal zone adjustment (breast ultrasound accreditation program requirements, 2012). 

     In an ultrasound examination, high-frequency sound waves are directed into the soft tissue, and then they are bounce off of structures reflected back to the transducer (Bubb, 2008).  An image of ultrasound is acquired based on the travel time and intensity of the sound beam as it reflects off of different structures (Bubb, 2008). 

     From Woodworth (2011), in an early analysis of 2500 women over the age of 30, the researchers concluded that ultrasound additional diagnostic value, which included differentiating between cystic and solid palpable breast masses, distinguishing between cyst and solid mass in non palpable masses found on mammography and follow up evaluation of symptomatic area of the breast that only appeared as uniformly dense fibroglandular tissue on mammography. 

     Evans and Harris (2009) stated that in subgroup analysis, the investigators found a higher sensitivity with combined mammography and breast sonography compared with mammography alone in patients of either under or over the age of 50.  The researchers reported in one study between January 2000 and August 2003, from patients who were undergoing evaluations in a breast clinic, the addition of adjunctive breast sonography with mammography was more sensitive than mammography alone which is 80.8 percent versus 56.6 percent (Evans & Harris, 2009).

2.2.1        Advancement of Modality

            Even though ultrasound is very useful at detecting breast cancer however at some point, there are also disadvantages.  According to Bubb (2008) the disadvantage of ultrasound breast is the potential for higher false positives that may lead to unnecessary biopsies.  Because of this, breast sonoelastography is introduced as the newest innovation in breast ultrasound.

            Breast sonoelastography also called tissue elastography or E-mode.  It measures the breast tissue’s elasticity and categorizes the result into an elasto-strain-ratio measurement (Bubb, 2008).  Consisting of attaching a small compression plate to the ultrasound transducer is a simple process of the E-mode technique and only very light compression is needed and applied as the sonoelastography software that acquires the image data (Bubb, 2008).  Bubb (2008) stated that by measuring the tissue strain of a lesion and compare it to the normal fatty breast tissue which resulting in a ‘fat-to-lesion ratio’, that is how the elasto-strain-ratio measurement characterizes breast lesions as either benign or malignant.  Tissue elasticity can range from very soft with lots of strain comparable to surrounding breast tissue which indicate a benign process, to very hard with little or no strain, which is highly suggestive of a malignancy (Bubb, 2008).  Appendix five shows example of breast sonoelastography images.  Bubb (2008) mentioned that from the study, statistical analyses of sonoelastography indicate an overall sensitivity of 80 percent, reaching 90 percent lesions that are five millimeter in size or less. 

            Another technology that is going to become popular today is breast ultrasound computer aided detection (CAD).  This is a tool that can help physician to interpret and evaluate breast ultrasound images in order to determine whether a biopsy is indicated (Bubb, 2008).  It is said that breast ultrasound CAD is helpful to distinguish between a BI-RADS three (probably benign) and a BI-RADS four (suspicious abnormality) category (Bubb, 2008).  Fom Bubb (2008) explains that after digital ultrasound images of a breast lesion are acquired, the sonographic appearance of the lesion can be evaluated by the CAD software.  First, the area or lesion in question needs to be selected by the user.  Then, the user needs to manually trace this area or just go through an automated process and identify certain image characteristics that help to differentiate between benign and malignant features.  These characteristics are the lesion’s orientation, shape, boundaries, margins, posterior acoustic features, echo patterns, calcifications, vascularity, and the integrity of the surrounding tissue.  The CAD software will calculate a BI-RADS category after all these characteristics have been evaluated and identified.  Lastly, the report will automatically be generated.  Appendix six shows an example image of ultrasound breast using CAD software.                 

2.2.2        Quality Monitoring

            From Performance and Practice Guidelines for Breast Ultrasound (2011), stated that quality control programs should be designed to maximize the quality of the diagnostic information, policies and procedures for monitoring and evaluating the effective management and proper performance of imaging equipment should be written by each facility, high resolution linear array transducers of at least 7.5 MHz frequency should be utilized for breast ultrasound diagnostic examinations, and annually those equipment performance should be monitored with standards for ultrasound imaging and phantom testing for resolution.

            American College of Radiology (ACR) recommends routine QC test that should be performed on all ultrasound units used for breast imaging and these are maximum depth of visualization and hardcopy recording with a tissue mimicking phantom test, vertical and horizontal distance accuracy test, uniformity test, electrical mechanical cleanliness condition, anechoic void perception, ring down, lateral resolution, quality control checklist, adherence to universal infection control procedures, clean transducers, and grey scale photography test (breast ultrasound accreditation program requirements, 2012).

        

2.3      Breast Magnetic Resonance Imaging (MRI)

               Bubb (2008) mentioned that now breast MRI plays a vital role in breast care management when it is very useful in evaluating benign conditions such as assessing the integrity of breast implants and also serves as an adjunct screening modality for the detection of certain types of mammographically or sonographically occult breast cancers in high risk patients.  Other than that MRI also plays vital role in staging by assessing tumor size and determines the extent of disease, such as multicentric, multifocal, or contralateral extension.  Bubb (2008) mentioned that the statistical analyses revealed that the sensitivity of MRI in detecting contralateral breast cancer is 91 percent. 

               Clayton, Davison, Bailey, Dall, Gilbert, and Jenkins (2012) suggested that high field modern MRI machines should be used for breast and very high field strength which is three Tesla and above can be used.  However minimum standard must be at least 1.5 Tesla.  Dedicated bilateral breast coils must be used with uniform signal homogeneity across the coils.  Appendix seven shows image of MRI machine with breast coil.  Both breasts should be examined where it can be achieved by scanning in the axial or coronal plane and alternatively, an interleaved sagittal approach can be used (Clayton et al., 2012).  Total examinations time usually less than 30 minutes.  Sequences used for MRI breasts are T2 weighted fast spin echo, T1 weighted spoiled gradient echo, and TI weighted spoiled gradient echo with fat suppression. 

               MRI produces cross sectional images of the patient’s anatomy using magnetic fields.  MRI does not use ionizing radiation.  According to Bubb (2008), by using a dedicated breast coil with recommended minimum field strength of 1.5 Tesla, conventional T1 and T2 weighted breast MRI allow the performance of chemical fat suppression.  Appendix eight shows example image of breast MRI.  Researchers noted that most breast cancers demonstrate an increased vascularity when compared to the surrounding tissue because majority of breast cancers form primitive blood vessels that shunt blood to the tumor bed.  During a fast dynamic imaging sequence, when MRI contrast agent is administered, if there is a malignant lesion, it will collect more of the contrast agent due to its increased vascularity (Bubb, 2008).  Because of this, the tumor will enhance compared to the surrounding breast tissue.  Gadolinium contrast is used to enhance the vascularity of malignant lesions (Prasad & Houserkova, 2007). 

               According to Evans and Harris (2009), from the study done on MRI patients where the cases were performed on a 1.5 Tesla strength MRI unit using imaging sequence that consisted of a localizing sequence followed by a sagittal fat suppresses T2 weighted sequence first and next a T1 weighted three dimensional fat suppressed fast spoiled gradient echo sequence was performed before and after injection of contrast media, researchers reported that among the 367 women screened, a biopsy for a non palpable lesion was recommended in 64 women which is 17 percent and cancer was found in 14 women which is 24 percent and that cancer was not evident through mammography or physical examination.  Evans and Harris (2009) noted that it is important to consider that MRI posts a diagnostic sensitivity for invasive breast cancer at a rate 90 percent but the specificity has been reported only 39 percent for detecting the difference between benign and malignant lesions.  However, for patients with breast implants, the researchers reported 71 percent sensitive and 91 percent specific to evaluate the implant device for potential rupture using MRI (Evans & Harris, 2009). 

2.3.1        Advancement of Modality

            Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) measurements are being added to conventional breast MRI studies.  This is to reduce the number of false-positives due to enhancement of some benign vascular lesions that look like cancer in T1 and T2 weighted breast MRI (Bubb, 2008). 

            DWI is a process in which during specific pulse sequences, the diffusion of water molecules is measured.  Positional change of the water molecules help to differentiate between benign and malignant lesions.  Molecules that show no or very little positional change are considered to have restricted diffusion which indicates a malignancy and molecules that show various positional changes are considered to have unrestricted diffusion which indicates a benign process (Bubb, 2008).

               During diffusion imaging there is an amount of signal drop in a mass and the ADC will measure that amount.  From Bubb (2008), there is statistical analyses conducted by the researchers revealed that ADCs greater than 1.2 indicate a benign process and ADCs less than 1.2 indicate a malignancy which is sensitivity and specificity of 100 percent.        

2.3.2        Quality Monitoring

            According to Clayton et al. (2012), there must be regular quality control checks to ensure that breast MRI screening centers meet the standards for equipment, image acquisition, and data storage.  Quality control of MRI systems used for diagnostic breast MR imaging also is important to ensure the production of high quality images by evaluating whether MRI scanner and coils used for breast imaging are performing consistently over time (Reeve 2011).  Tests like spatial resolution, slice thickness, and RF uniformity involve measures which require access to specialist test objects and analysis software (Clayton et al., 2012).  There is also an annual or start up or post major upgrades checks to confirm that the contrast of the T1 weighted dynamic sequence is acceptable, to confirm that MR scanner is within the manufacturer’s specification, and to confirm that the breast coils is within the manufacturer’s specification (Clayton et al., 2012).  Other than that, there is also routine weekly QC check using a phantom in the breast coil to monitor signal to noise ratio and suppression effectiveness.              

3            OTHER IMAGING MODALITY TECHNOLOGIES ADVANCEMENT USED IN MEDICAL

      Noted that the addition of adjunctive modality technologies advancement in breast imaging include sonoelastography and computer aided detection in ultrasound, diffusion-weighted and apparent diffusion coefficient magnetic resonance imaging, nuclear medicine scintimammography, positron emission tomography combined with computed tomography (CT), electrical impedance tomography (EIT), and optical imaging.  These adjunctive modalities are used to provide the doctors with additional confidence in their initial diagnosis. 

      Bubb (2008) mentioned that new advancement in nuclear medicine imaging of the breast is called scintimammography where a radioactive substance composed of technetium-99M-sestamibi is injected intravenously and images are acquired using a high resolution breast specific gamma camera and the uptake of the radioactive tracer that was injected is recorded.  From Bubb (2008), statistical analysis of scintimammography shows a sensitivity of approximately 86 percent for detecting breast lesions smaller than one centimeter.  Scintimammography can be used as an adjunct imaging modality and it gives benefits to high risk patients, patients with dense breast tissue, and to those who cannot undergo MRI procedure (Bubb, 2008).  Also it can image breasts with implants, can image large and palpable abnormalities, and can be used when multiple tumors are suspected (Sree et al., 2011).  

      Another advancement technology as adjunct modality in breast imaging is positron emission tomography (PET) combined with computed tomography (CT) or can be called PET/CT.  PET is also a nuclear medicine imaging study that can detects metabolic activity in different cells which is very useful to detect axillary lymph node involvement of breast cancer and PET/CT is to identify axillary metastasis by detecting regional lymph node involvement (Bubb, 2008).  Researchers reported from the study done regarding PET/CT shows noninvasive PET/CT at detecting axillary lymph node involvement indicate 94 percent sensitivity, 86 percent specificity, and 89 percent accuracy (Bubb, 2008).  The principle of PET uses a radioactive isotope, fluorodeoxyglucose (FDG), and it is injected to the patients intravenously.  Malignant tumor cells will absorb more of the FDG because it has higher metabolic rates than the surrounding tissue and as the radioisotope decays inside the tumor cells, positrons are emitted, which produce photons that are detected during image acquisition and appear as hot spots of high metabolic activity (Bubb, 2008).  The pathologic metabolic uptake from PET can be viewed in CT which provide cross sectional anatomy and precise anatomical location of the activity.  Appendix nine shows axial image of FDG PET CT of the left breast.  However, there are also limitations where PET is very expensive and yields poor resolution images and the patients are subjected to radiation exposure (Sree et al., 2011). 

      Prasad and Houserkova (2007) mentioned that CT is useful for revealing the problems in the diagnosis of breast lesions.  CT is an imaging study in which an x-ray tube rotates 360 degrees around an anatomical structure acquiring data and these data are reconstructed to form cross sectional images (Bubb, 2008).  According to Prasad and Houserkova, dynamic contrast enhanced CT of the breast has been found to be effective for the detection of intraductal extension of breast carcinoma.  From Evans and Harris (2009), the authors mentioned that breast CT is still in its early stages and in clinical trials and accuracy statistic are not yet available.  However, the researchers initially reported that the breast CT system provides an excellent depiction of the breast anatomy, good visualization of microcalcifications, and accurate depictions of soft tissue components of any lesions found in the study (Evans & Harris, 2009). 

      Another new imaging method is electrical impedance tomography (EIT).  According to Prasad and Houserkova (2007), EIT system utilizes an array of electrodes to apply currents to an imaging domain and measures the resulting voltages on the periphery.  Then the measurement results input to a reconstruction algorithm to produce an image of the impedance distribution inside the domain.  The breasts scanned by electrical impedance imaging for electrical conductivity based on the idea that breast cancer cells conduct electricity better (Prasad & Houserkova, 2007).  In EIT, 2D or 3D images are reconstructed from a large number of impedance values which are captured by placing electrodes around the breast surface in a circular fashion (Sree, Ng, Acharya, & Faust, 2011).  However according to researcher, EIT  still not recommended to use in  breast cancer screening because it has not undergone enough clinical testing even though studies have shown that malignant breast tumors have lower electrical impedance than the surrounding normal tissues  (Prasad & Houserkova, 2007).  It has been suggested that the separation of malignant tumors from benign lesions based on impedance measurements needs further investigation.

      According to Sree et al. (2011), optical imaging uses near infrared wavelength light to detect lesions inside the breast.  Types of optical imaging are diffuse optical imaging, diffuse optical tomography, and optical mammography which each of these use different wavelength of light to detect breast lesions.  Diffuse optical imaging uses near infrared light to penetrate into the breast, while diffuse optical tomography uses near infrared light of wavelength 700 to 1000nm, and optical mammography uses laser light (Sree et al., 2011).  Study shows that the new direction is to develop standardized diffuse optical imaging platforms that can be used as standalone devices or in conjunction with MRI, mammography, or ultrasound (Sree et al., 2011).  Sree et al. (2011) also noted that diffuse optical imaging is hoped to provide new insights for detecting disease in mammographically dense tissue, distinguishing between malignant and benign lesions, and understanding the impact of neoadjuvant chemotherapies.

4            DISCUSSION

    Researchers have shown that in their studies, digital breast tomosynthesis (DBT) is useful for all patients regardless of breast density, but its greatest benefits is especially in women with dense breast tissue again (Levine, 2013).  Other benefits of DBT are higher cancer detection rates which allow radiologists to discover more early stage breast cancers to save lives.  DBT gives so much benefit because DBT act as combined 2D digital mammogram from different angle when taking the image of the same breast.             

Other than that, all the researchers agree that combining mammography and ultrasound improves the sensitivity of imaging diagnosis.  As well as combining mammography and ultrasound with other modalities.  Some said that ultrasound breast is very useful especially in the younger patient population who typically has very dense breast tissue when mammography alone may miss most detection of cancers in dense breasted women.   However, from one of the study, Sree, Ng, Acharya, and Faust (2011) stated that ultrasound screening in asymptomatic women causes unacceptable false positive and false negative outcomes.  So the author suggested that ultrasound screening should always be used with mammography or other imaging techniques because it alone will not be able to detect lesions accurately (Sree et al., 2011).  When mammogram and ultrasound have been combined, the outcome of the report should include a description of the size, shape, margin, and density of the lesion, location of the lesion and associated findings as well as the changes of the lesion since the previous studies performed (Evans & Harris, 2009).  Evans and Harris (2009) noted that this approach increases the power of the evaluation by taking advantage of all the data gathered and therefore raises the diagnostic accuracy of the combined examination.       

    As for breast MRI, there are several numbers of accepted indications for it.  There are women who are high risk for screening, patients with no primary breast carcinoma on physical examination, mammography and ultrasound but have an axillary lymph node presentation, patients who have augmentation breast implant done, assessing response to neoadjuvant chemotherapy, and clinical problem solving (Solin, 2010).  It is said that MRI is 100 percent sensitive for breast lesions compared to only 53 percent for mammography paired with breast sonography (Evans & Harris, 2009).  However MRI breast is not good at diagnosing ductal carcinoma in situ (DCIS), may lead to many false positives, may not show all calcifications, and more expensive (Sree et al., 2011).  MRI also lead to many false positive which mean the specificity of MRI is low as reported in Evans and Harris (2009).  Because of this we should consider using MRI together with mammography to examine suspicious breast lesions and also with breast sonography to achieve an increased level of diagnostic accuracy.  The researchers noted that those issues highlight the need to use a multimodality approach to avoid diagnostic pitfalls (Evans & Harris, 2009).         

    From Garami, Hascsi, Varga, Dinya, Tanyi, and Garai (2011) who had done a comprehensive study of FDG PET/CT performed on 115 breast cancer patients in whom traditional diagnostic modalities like mammography show no distant of metastases or extensive axillary.  The results from this study show the sensitivity of the traditional diagnostic modalities in the detection of multifocality was 43.8 percent while PET/CT was 100 percent.  In the assessment of axillary lymph nodes, ultrasound had a sensitivity of 30 percent and specificity of 95 percent while the corresponding estimates for PET/CT were 72 percent and 96 percent.

    Other than PET combined with CT, there was also a study done on MRI combined with PET.  Sree et al. (2011) suggested that in their study, the combined use of MRI and PET were complementary and offered advantages over clinical breast examination.  PET was more accurate in predicting pathologic non response, and the MRI used to evaluate the response correlated well with macroscopic pathologic complete response (Sree et al., 2011).

5            CONCLUSION

      In breast imaging, mammography is the gold standard for breast cancer screening.  However, the new advance technologies that have been introduced have made a multimodality approach to breast imaging happen in clinical practice.  These new technological advancements modalities are improving image quality and most importantly enhancing the diagnostic accuracy of breast detection, staging, and treatment.  Most hospitals and centers have accepted the fact that breast ultrasound and breast MRI as a multimodality approach that can help mammography in diagnosis breast cancer especially in high risk women and women with mammographically dense breasts.  Other modalities for example like scintimammography, PET, breast CT, and many more may also provide benefit to breast imaging.  With these new technologies, it has been proven that could prevent unnecessary biopsies and reduce patient anxiety due to inconclusive findings.  However, more research is needed to confirm the role and characteristics of multimodality breast screening for future.

6            REFERENCES

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Clayton, D., Davison,C., Bailey,C., Dall,B.J., Gilbert, F., & Jenkins, J. (2012). Technical         Guidelines for MRI for the Surveillance of Women at Higher Risk of Developing Breast        Cancer. Retrieved April 30, 2013, from       www.cancerscreening.nhs.uk/breastscreen/publications/nhsbsp68.pdf

Evans, K.D. & Harris, A. (2009). A Multimodality Approach to Breast Imaging. Retrieved       May 01, 2013, from www.eradimaging.com/site/article.cfm?ID=744

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Levine. G.M. (2012). Tomosynthesis Improves Breast Cancer Detection Especially in   Women With Dense Breast Tissue. Retrieved April 30, 2013, from http://www.imaging-      radiation-oncology.advanceweb.com/.../3-D-Mammography

NHS Cancer Screening Programme (2006, April). Quality Assurance Guidelines for     Mammography Including Radiographic Quality Control. Retrieved May 02, 2013, from    www.gmccn.nhs.uk/.../QualityAssurance

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7            APPENDICES

7.1      Appendix 1

Figure 1. Screen film Mammography Unit. Reprinted from Introduction to Breast Cancer and Mammography, n.d., Retrieved from http://www.eradiography.net/articles/mammo/mammo_introduction.htm. Reprinted with permission

7.2      Appendix 2

Figure 2a. Prototype Tomosynthesis Unit. Reprinted from Digital Breast Tomosynthesis, by S.P. Poplack, T.D. Tosteson, C.A. Kogel, & H.M. Nagy, 2007, Retrieved from http://img.medscape.com/fullsize/migrated/562/866/ajr562866.fig1.jpg. Copyright 2007 by American Roentgen Ray Society. Reprinted with permission.

Figure 2b. Digital Tomosynthesis Mammography Unit. Reprinted from Hologic The Women’s Health Company, by Medical Expo, 2003, Retrieved from http://img.medicalexpo.com/images_me/photo-g/digital-tomosynthesis-mammography-unit-70711-3323545.jpg. Copyright 2013 by Medical Expo. Reprinted with permission.

7.3      Appendix 3

Figure 3. 2D Digital Mammogram compared to a representative 1mm slice from a 3D Digital Breast Tomosynthesis Exam From the Same Patient. Reprinted from Tomosynthesis Improves Breast Cancer Detection, Especially in Women with Dense Breast Tissue, by G.M. Levine, 2012, Retrieved from http://www.advanceweb.com/SharedResources/Images/2012/012312/mammoscans_300.jpg. Copyright 2013 by Merion Matters. Reprinted with permission.

7.4      Appendix 4

Figure 4a. Ultrasound Machines. Reprinted from United Medical Instruments, by L. Patton, 2013, Retrieved from http://go.umiultrasound.com/Portals/200822/images/umi_family%20revised.png. Copyright 2013 by United Medical Instruments, Inc. Reprinted with permission.

Figure 4b. Ultrasound Transducers, Linear Transducer for Breast. Reprinted from Medical Equipment Blog, by MedWOW, 2011, Retrieved from https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_UJpSD-MOpxAuc7cEomlc-EdIOY6AHgmnU2tGUYqEwOXm9orhzRY2wJcGln51-JwOczvxGKtgmB7stba1C9FpsOX03Aa3nPO2P1JyjhPl8sKTdRA8GiY4uorpHHheenvwUkgHy_xfoEE/s400/Ultrasound+Probes.jpg. Copyright 2011 by MedWOW. Reprinted with permission.

7.5      Appendix 5

Figure 5a. An Irregular Fibroadenoma on Sonoelastography with a Fat-to-Lession Ratio (FLR) of 1.2, Indicating a High Tissue Strain and Benign Process. Reprinted from New Technological Advancements In Breast Imaging, by K.S. Bubb, 2008, Retrieved from http://www.eradimaging.com/cffm/custom/Breast%20Cancer%20-%20Oct-08/Figure-3.jpg. Copyright 2013 by Eradimaging.com. Reprinted with permission.

Figure 5b. Blue Indicates a Lesion with No Tissue Strain (Hard) with a Fat-to-Lesion Ratio (FLR) of 8.9 Highly Suggestive of a Malignancy. Reprinted from New Technological Advancements In Breast Imaging, by K.S. Bubb, 2008, Retrieved from http://www.eradimaging.com/cffm/custom/Breast%20Cancer%20-%20Oct-08/Figure-4.jpg. Copyright 2013 by Eradimaging.com. Reprinted with permission.

7.6      Appendix 6

Figure 6. Using Computer Aided Detection (CAD) Software for Breast Ultrasound Imaging to Identify the Characteristic of the Lesion Using BIRADS Lexicon. Reprinted from Medipattern, by RSNA, 2007, Retrieved from http://rsna2007.rsna.org/rsna2007/V2007/services/exbdata/1668/images/BCAD1_1.JPG. Copyright 2007 by Radiological Society of North America, Inc. Reprinted with permission.

7.7      Appendix 7

Figure 7. Breast MRI. Reprinted from Leading Technologies and Treatments, by Hartford Hospital, n.d., Retrieved from http://www.harthosp.org/Portals/1/Images/26/SentinellBreastCoil.jpg. Copyright 2013 by Creative Change, Inc. Reprinted with permission.

7.8      Appendix 8

Figure 8. T1 Weighted Fat Saturated Axial MRI Showing Even Fat Suppression. Reprinted from New Technological Advancements In Breast Imaging, by K.S. Bubb, 2008, Retrieved from http://www.eradimaging.com/cffm/custom/Breast%20Cancer%20-%20Oct-08/Figure-5.jpg. Copyright 2013 by Eradimaging.com. Reprinted with permission.

7.9      Appendix 9

Figure 9. FDG PET CT Axial Image Demonstrating the Dominant Suspicious Lobular Soft Tissue Mass in the Upper Inner Quadrant of the Left Breast. Reprinted from “Nonvisualization of Sentinel Node by Lymphoscintigraphy in Advanced Breast Cancer”, by B. Wosnitzer, R. Mirtcheva, & M. Ghesani, 2010, Radiology Case Reports, 5(3). Copyright 2010 by The Authors. Reprinted with permission.