Breast imaging

Interventional procedures

 

Fine-needle aspiration biopsy (FNAB)

FNAB is a valuable modality which is used to evaluate breast lesions, palpable as well as non-palpable. In many institutions fine needle aspiration biopsy is part of the routine work-up of all breast lesions that need further characterization over and above that obtained by physical examination and mammography. With proper use of FNAB the number of surgical biopsies for benign lesions can be reduced. Furthermore, a definitive diagnosis can be made preoperatively in most patients with carcinoma. Thus, different treatment options can be discussed with the patient, and surgery can in most cases be performed as a one-stage rather than a two-stage procedure.

Certain principles must be adhered to. The results of cytology should always be considered together with those of mammography and, in the case of a palpable lesion, the physical findings. If representative material is not obtained, the cytology should be disregarded. Needless to say, the cyto-pathologists must be familiar with breast cytology especially regarding small and borderline lesions. Ideally, the results of the various modalities should be discussed in multidisciplinary conferences between radiologists, cytopathologists, surgeons, and oncologists.

X-ray guided FNAB

Non-palpable breast lesions can be localized using a 3-dimensional stereotactic technique or a 2-dimensional co-ordinate grid technique. As was discussed above, US can also be used to guide FNAB. Also, for palpable lesions sometimes an X-ray- or US-guided FNAB is used, if the tumor is much smaller than the physical finding or if it is not clear whether the physical finding corresponds to the mammographic finding.
The stereotactic localization technique implies that the position of the lesion is calculated from two-dimensional x-ray pictures of the lesion with a projection difference of approximately 30 degrees (Fig. 5). From these two pictures the X-, y- and z-coordinates of the lesion can be calculated, as well as the necessary adjustments of the needle-holder. A 21 or 22 gauge needle is generally used together with a 10 ml syringe in a

Figure 5. 68-year old asymptomatic woman. Screening mammogram reveals several small nodules in the left breast. The figure shows two stereoscopic views of one of the nodules. Also illustrated are the position of the needle in relation to the nodule, the aperture in the compression plate as well as the reference lines in the form of an inverted T The aspirate contained benign epithelial cells. Microscopic examination of the surgical specimen showed multiple papillomas without evidence of malignancy.

special holder. Usually, 2 to 5 separate aspirations are made from different areas of the lesion. The aspiration technique is critical: the target tissue must be fixed and the amplitude of the needle strokes sufficient.

It is important to be aware of the pitfalls and limitations of FNAB. Sampling error due to improper position of the needle may occur. This in turn may be due to needle deviation caused by the bevelled tip of the needle or due to the fact that the les ion is difficult to delineate in both of the two stereotactic views. It is important to verify the position of the needle by taking pictures of the needle in position immediately prior to aspiration. Further reasons for sampling error may be abundant fibrosis in the lesion or necrosis. A lesion may be complex, some parts being benign, others malignant.

Suboptimal smearing technique is another reason for diagnostic error. Smears should be prepared according to the rules given by the laboratory to which they are sent.

The co-ordinate grid technique is another way of performing x-ray guided FNAB. The aperture in the compression plate is lined by a coordinate grid and only one film is exposed. The x- and y-coordinates of the lesion are easily defined on the film, and the point of interest is then marked on the surface of the breast. The depth of the lesion has to be estimated from previous mammograms. After introduction of the needle, a film should be exposed to verify the needle position and to provide the

Figure 6. Specimen radiograph showing a duster of calcifications which has been removed with a wide margin. A hook wire was used to localize the duster. Also, in the specimen the duster has been marked with a needle. Microscopic examination of the specimen revealed a non-invasive intraductal carcinoma of comedo-type.

necessary adjustments for subsequent punctures. With this technique one should be aware of the problem of beam divergence resulting in a projection error in all points outside the area of the central ray. A co-ordinate grid technique is a simple way of localising a lesion and the results are satisfactory, provided the examiner is familiar with the technique.

Preoperative localization of non-palpable lesions

X-ray, as well as ultrasound guidance can also be used for preoperative localization of non-palpable lesions. A hook wire is usually introduced through a needle. Depending on the surgeon's preference different approaches can be used. For lesions in the upper quadrant of the breast we usually use the craniocandal approach. If the lesion is in the lower quadrants, a medial or lateral approach is generally preferred. A mammogram showing the exact position of the localizing device in relation to the lesion should always be obtained and be available to the surgeon.

Instead of placing a metal wire, carbon powder can be injected.

If the lesion is located superficially a lead marker can be placed on the skin over the lesion. After obtaining a new mammogram to confirm the correct position of the lead marker, the location of the lesion can then be marked on the overlying skin.

A specimen radiogram should always be taken to verify that the lesion has been removed (Fig. 6). If necessary, the lesion can be marked with a needle to guide the pathologist.

Galactography

Galactography is the radiographic imaging of the duct system of the breast using contrast medium injected through a duct opening on the nipple. The main indication for galactography is bloody nipple discharge and possibly also serous nipple discharge. Bloody nipple discharge is associated with malignancy in about 20% of cases, serous nipple discharge in a far lower percentage. Other types of nipple discharge, such as blue, green, yellow and brown discharge are practically always associated with fibrocystic or other benign changes.

Technique
The discharging duct opening on the nipple must be clearly identified. For this purpose headmounted magnifying glasses may be together with a bright light. If there is a significant discharge, the opening is usually dilated and easier to find and cannulate. A blunt, bent needle or a plastic catheter can be used. Any type of water soluble contrast medium is appropriate. Usually a small amount, 0,1-1,0 ml is injected. It is important to stop the injection when the resistance increases or when the patient experiences pain or tension in the breast. The needle or catheter can be left in place while taking a craniocaudal and lateral view, or, it can be withdrawn. The use of magnification technique is to be preferred. Usually enough contrast material will stay in the duct system during moderate compression. The duct opening can also be sealed by applying a small amount of collodium to the nipple.

Findings
In the presence of a significant discharge the duct system is usually dilated. A solitary, polyp like contrast defect is a common finding, almost always representing an intraductal papilloma (Fig. 7). Sometimes extensive intraductal filling defects with more or less complete obliteration of ducts are found. Differentiation between papillomatosis and intraductal carcinoma is not possible in such cases (Fig. 8). In some patients with bloody nipple discharge duct ectasia is the only finding.

In the presence of intraductal filling defects it is often wise to repeat the galactography to exclude false positive results due to air bubbles or debris in the ducts. Cannulation and injection of contrast medium is repeated after expressing as much as possible of the contrast medium from the previous injection.

	Figure 7. 67-year old patient with a discharge from the left nipple. The discharge had been serous but turned bloody a few days before the current examination. Cytology of the discharge showed only red blood cells. The galactogram shows two filling defects, the larger one measuring 4x8 mm (arrow). The duct is dilated. On microscopy an intraductal papilloma (benign) was found.
	Figure 8. 36-year old woman with a 13-year history of non-bloody discharge from the left nipple. Cytologic examination of the discharge showed red blood cells and no malignant cells. On galactography several filling defects were demonstrated (arrows) in a dilated duct system. Microscopy of the resected specimen showed multiple papillomas.

Again, after completion of the examination as much as possible of the contrast medium should be expressed.

To guide the surgeon, a mixture of contrast medium and blue dye is injected with the technique described above. Pictures should be taken to confirm that the proper duct has been injected.

Figure 9. 76-year old woman who was referred because of a 2,0 cm palpable mass in the lateral aspect of the left breast. Mammography confirmed this finding and in addition showed another suspicious tumor in a different quadrant. Microscopic examination of the surgical specimen showed 2 separate carcinomas and one metastatic node in the axilla.

 

 

Ingvar Andersson and Baldur F. Sigfússon