Breast Imaging Modalities

Dr. Y. Madhu Madhava Reddy

Mammography

• A mammogram can find breast cancer when it is very small -- 2 to 3 years before patient can feel it.

• No screening tool is 100% effective. Good quality mammograms can find 85-90% of cancers

Routine Images - aka “screening mammo’’

• Positions• CC - cranio caudal• MLO – mediolateral oblique

Positioning of Breast for CC View

GALACTOGRAPHY / DUCTOGRAPHY

• Breast ductography is an imaging technique which is used to evaluate lesions causing nipple discharge. It helps in precisely locating the mass within breast tissue and gives useful information for surgical approach and planning.

Indications and Contraindications• The most common use of galactography is to evaluate a

woman who has a unilateral bloody or clear discharge from her breast nipple and an otherwise normal mammogram.

• Galactography is typically NOT called for in women with the following conditions:

• A discharge that is milky, yellow, green, or gray is usually not a cause for concern, especially if it comes from multiple ducts in the breast.

• A discharge that is from both breasts in a woman who has not had children may indicate a side effect from a drug, or may be related to a pituitary etiology.

Technique

• A blunt-tipped sialogram needle (30-gauge) is used for performing ductogram. The abnormal duct is identified and cannulated. Approximately 3 ml of contrast is injected into the duct and canula is taped to the nipple.

• A standard two view mammography (or CC and ML projections) are obtained.

• Ductal filling defects are generally caused by papilloma or DCIS.

Filling defects d/t intraductal Carcinoma

X ray guided Procedures

• Stereotactic guided FNAC: • For lesions that are not seen or are poorly

visualised on ultrasound, mammographic guidance is required for needle biopsy.

• The most common method currently in use is an add-on stereotactic device which is used with a conventional upright mammography machine.

Technique• The lesion is demonstrated on paired stereotactic views

obtained with the X-ray tube angled 15° either side of the central tube position.

• Measurements defining the position of the lesion on the stereotactic views are used to determine the position of the needle guide in the X, Y and Z axes.

• When the needle, of specified length, has been inserted through the guide into the breast, check stereotactic views are obtained to ensure that the tip of the needle is correctly positioned in relation to the lesion. If the position is not correct, the needle can be repositioned and further check films obtained.

Different parts of the lesion are sampled by moving the needle guide 2-3 mm in the X andY axes. Up to five aspirates are usually obtained.

Stereotactic guided Core biopsy

• Conventional mammography with add on stereotactic equipment and analogue imaging can be used for stereotactic core biopsy.

• More accurate results are obtained using dedicated prone stereotactic biopsy equipment with digital imaging.

Technique

• Using this equipment, the patient lies in the prone or prone oblique position and the breast passes through an aperture in the table.

• The direction of the X-ray beam is horizontal and stereotactic views are obtained by rotating the tube 15° either side of the central position. The digital X-ray images obtained are displayed on a computer screen within approximately 5 seconds of exposure, and the computer offers rapid contrast adjustment and zoom features.

Stereotactic guided core biopsy

Stereotactic guided core biopsy• Target areas for biopsy are selected on the computer screen

and the position and angulation of the biopsy needle/gun holder are adjusted automatically.

• A 14G needle is used; after insertion under local anaesthetic, check films are taken to ensure correct positioning .

• Check films can also be taken after firing the biopsy gun to ensure that the lesion has been traversed by the needle. Five or more core biopsies are usually obtained.

• Core biopsy specimen radiographs are taken when sampling areas of microcalcification to ensure that representative tissue has been obtained

Stereotactic guided core biopsy

Vaccum Assisted Core Biopsy

• This procedure allows a larger tissue sample to be obtained.

• An I I G probe with a biopsy port attached to a vacuum-producing device is inserted into the breast under local anaesthetic and stereotactic guidance.

• Tissue from the target area is sucked into the biopsy port by the vacuum and is then separated from the surrounding breast by a rotating cutting cylinder which passes down within the probe.

Vaccum Assisted Core Biopsy

• The tissue sample is then delivered by withdrawing the cutting cylinder-the probe is left in position in the breast and is rotated so that the biopsy port is aligned with the next site for sampling and in this way multiple samples are taken and small clusters of micro calcification are usually completely removed.

Vaccum Assisted Core Biopsy

• If the mammographic marker is removed, a small metal clip / gel pellets or combined gel-metal (USG Sensitive) markers are deployed at the site of the biopsy to allow accurate localisation should subsequent surgical excision be necessary.

• Vacuum-assisted core biopsy has also been used under ultrasound guidance for sampling of soft tissue lesions, and under MRI guidance for lesions which are not visible using either mammography or ultrasound.

Core specimen radiography. A specimen radiograph showing a good yield of microcalcifications in several vacuum-assisted mammotomy biopsy cores.

Preoperative localisation of Non palpable lesions

• For the non palpable breast lesions the position of the lesion is marked using a wire with a hook or barb on the end to prevent movement of the wire within the breast. The wire is contained within a needle which is inserted into the breast under local anaesthetic, using either X-ray or ultrasound guidance.

Preoperative localisation of Non palpable lesions

• When the tip of the needle has been shown to be satisfactorily positioned within 10 mm of the lesion, the needle sheath is withdrawn leaving the wire in situ.

• Check craniocaudal and lateral views are obtained to show the final position of the wire in relation to the lesion.

• Peroperative specimen radiography is mandatory to ensure that the excised breast tissue contains the mammographic abnormality.

DIGITAL TOMOSYNTHESIS

US Elastography

• Ultrasound (US) elastography is an imaging technique that can visualize tissue elasticity (stiffness) in vivo.

• Two types of Elastography• Strain Elastography (SE)• Shear wave elastography (SWE)

US elastography

• The most common type of strain elastography (SE) displays relative tissue displacement under compression, whereas SWE displays an image of the shear-wave speed using acoustic radiation force excitation.

Interpretation of US Elastography• Strain Elastography • When the breast tissue is pressed by the transducer, a hard

lesion undergoes less strain than does the surrounding soft background.

• The relative strain in the tissue is displayed in a black-and-white (bright, soft; dark, hard) or color-coded (red, soft; blue, hard) image.

• In SE, the lesion size or area on the elastogram is compared to the corresponding lesion on the B-mode US image, as malignant lesions appear larger on elastograms than on B-mode US images.

Strain Elastography

• Itoh et al. proposed the 5-point scale elasticity score indicating an increasing probability of malignancy that is most commonly used for SE.

• A cut-off point between the elasticity scores of 3 and 4 was initially suggested to differentiate benign from malignant breast lesions.

• However, a cut-off point between the elasticity scores of 1 and 2 or 2 and 3 was used in several studies and achieved better diagnostic performance with less interobserver variability.

Strain Elastography• Recently, elasticity scores are classified into three categories: • score of 1 (even strain across the entire lesion) as negative, • scores of 2 and 3 (uneven strain in the lesion) as equivocal,

and • scores of 4 and 5 (no strain across the entire lesion) as

positive results. • A specific bull’s eye artifact on black-and-white images or an

aliasing artifact that appears as a blue-green-red (BGR) pattern on colorcoded images can be observed in simple cysts.

Shear-Wave Elastography• Using SWE, transversely oriented shear waves are generated by

acoustic radiation force, and these waves propagate faster in hard tissue than soft tissue.

• A color-coded image displaying the shear wave velocity (m/sec) or elasticity (kilopascals, kPa) for each pixel in the region of interest (ROI) is acquired.

• Generally, a color scale ranging from 0 (dark blue, soft) to +180 kPa (red, hard) is used for breast lesions. A variety of qualitative and quantitative parameters of SWE have been studied so far , and the most useful SWE feature is the color assessment of the maximum elasticity, which is correlated with the maximum elasticity value (kPa).

Shear-Wave Elastography• The positive predictive value for malignancy increases with increasing

elasticity, from 0.4% for dark blue to 81.8% for red colors. • The maximum elasticity colors on SWE can be classified into three

categories: • dark blue and light blue colors (representing soft elasticity) as negative, • green and orange colors (intermediate elasticity) as equivocal, and red

colors (hard elasticity) as positive.

• Signal-void areas that are not color-coded even in the penetration mode can appear in simple cysts or in very hard masses with dense collagen deposition, as shear waves cannot propagate through them.

MRI of Breast

Standards for the performance of breast MRI

MRI of Breast

• The fat have faster relaxation times (greater interaction between molecules), so their T1 signal is shorter than pure water; thus, fat has the shortest T1 relaxation time. By convention, tissues with short T1 are presented as bright signals on T1 images.

MRI of Breast

• Signals from Water: tissues with a long T2 are presented as bright signals on T2-weighted images. Thus, cysts (that contain fluid) with long T1 are dark on T1-weighted images and those with long T2 are bright on T2-weighted images.

On MRI this cyst had a characteristically low signal intensity (black) on this T1-weighted image (A) and a high

signal intensity (white) on the T2-weighted image (B).

FAT Suppression :• Because of the high signal intensity of fat on T1

images, it is often difficult to appreciate enhancing lesions on gradient-echo images from the high signal produced by fat on T1-weighted images. Consequently, methods have been devised that eliminate the high signal from fat so that the tissues that enhance following contrast administration are more easily appreciated .

Fat suppression makes enhancing lesions easier to appreciate. Fat has low signal intensity on this fat-saturated T1-weighted image (A) prior to the IV administration of contrast. The cancer in the left breast is more evident on the first fat-saturated set of

images following contrast injection

Breast MRI indications

• 1-Preoperative evaluation of patients with newly diagnosed breast cancer:• when combined with mammography and

clinical breast exam, has been shown to provide sensitivity of 99% for the preoperative assessment of the local extent of disease in patients with newly diagnosed breast cancer.

• The purpose of MRI is to detect the presence of multifocal and multicentric disease as well as to detect bulky residual disease at the lumpectomy site in order to allow directed re-excision.

• malignancies may enhance at much more rapid initial rates than benign lesions.

• Breast cancer staging is based on the extent of local-regional disease in the breast and axilla, which has predictive value regarding the patient's prognosis and dictates treatment options.

• MRI sensitivity rates for the detection of invasive breast cancer are estimated to be as high as 95-100%.

•

Breast cancers are usually irregular in shape and heterogeneous in their enhancement on MRI.

• 2- evaluation of breast cancer patients treated with neoadjuvant chemotherapy. MRI has been used to monitor treatment response to neoadjuvant chemotherapy in patients with locally advanced cancer.• Change in tumor vascularity/enhancement

appear to explain changes in functional dynamic contrast assessment and can be seen after only one cycle of chemotherapy.

• Neoadjuvant chemotherapy. Sagittal post contrast fat suppressed T1W image prior to chemotherapy shows an enhancing mass correlating to a biopsy-proven invasive ductal carcinoma (A). Following chemotherapy, a comparable image shows only a small area of residual enhancement (B)

• 3- evaluation of patients with metastatic axillary lymphadenopathy and an unknown primary malignancy.

• 4- evaluation of breast cancer patients with positive surgical margins following breast conservation therapy.• MRI can be useful in determining the extent of

residual disease when margins are positive and the mammogram is not helpful.

Postsurgical MRI can demonstrate residual malignant disease. The postoperative MRI shows the seroma cavity on both the T2 images

(A) Retropectoral and (B) retroglandular placement of implants on MRI. Sagittal T1-weighted images of two

different patients with silicone implants.

•5- determination of silicone breast implant integrity.

• 6-breast cancer screening in high risk women.

• 7- use of breast MRI as a problem-solving tool for equivocal mammographic findings and for 3-dimensional localization of a lesion seen.

• 8- Evaluation of occult breast cancer• In patients with an occult primary

presenting with axillary lymphadenopathy or Paget's disease, MRI has been shown to identify the primary in many patients, thus allowing for conservative surgery rather than mastectomy.

Detection of occult malignancy. This patient had a positive axillary lymph node with a negative clinical examination

• 9-small breast (MRI) is well suited to the investigation of breast cancer by virtue of its noninvasive nature and its multiplanar imaging abilities.

• 10-Post surgical scar vs. recurrent tumor• In cases where mammography and ultrasound are

inconclusive in patient suspected of recurrent disease, MRI can be helpful.

• Breast tissue can show enhancement for up to 18 months following radiation therapy.

Invasive breast cancer visible on T1-weighted image because of the surrounding fat.

Cysts are bright on T2. In this mammogram of the right breast (A), the dense tissues obscure the cysts that are easily seen on the T2-weighted MRI

examination (B).

Blood in the ducts can be bright on T1. This patient had a bloody nipple discharge on the right. The blood in the duct is bright on the precontrast T1

image.

• 11-Breast MRI has consistently been found to detect additional unsuspected malignancy within the ipsilateral breast(in 10% to 27% of patients).

12-Pectoral muscle tumor invasion. .

• C. Inappropriate Use of Breast MRI• 1. Screening of general population• At present there is no data to support the

use of MRI as a screening tool.• To date, there are no studies demonstrating

decreased mortality by the use of MRI. Not all cancers seen on mammography can be identified in MRI.

• 2. Differentiation of benign & malignant lesions• Because of an overlap between the

enhancement and morphological characteristics of benign and malignant lesions, MRI cannot be used as a substitute for biopsy.

Scinti Mammography

Indications for scinti-mammography

• Indeterminate lesions• Dense Breasts• Implants• Post Sx /RT• Bone scan• Sentinel node biopsy

Indication for molecular imaging• Staging of patient with distant mets• Loco regional extent• Response to therapy• Restaging of patient with loco regional

recurrence/mets• Monitoring response to therapy• Lymph node and mets• Dense breast• Implants• Localize Primary in presence of mets• Bone metastasis

PET Imaging

CAD• Computer-aided detection (CAD) is a computer software

system that is designed to aid the film reader by placing prompts over areas of concern, and to try to reduce observational oversights. CAD systems are highly sensitive for detecting cancers on screening mammograms. CAD software will correctly prompt around 90% of all cancers, with 86–88% of all masses and 98% of microcalcifications correctly marked. Specificity is much more of a problem with a high rate of false-positive prompts. The number of false prompts will vary according to the level of sensitivity at which the system is set; typically there are between two and four false prompts per study

CAD

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