Orthogonal Radiographic Guidance (X-Ray–Guided Needle Localization)

One guidance method uses an upright mammographic unit with a compression plate that has an open aperture with an alphanumeric grid or that contains a series of holes. To perform needle localization, the radiologist reviews the original orthogonal mammograms to identify the shortest distance to the lesion from the skin surface. The technologist places the aperture over the skin closest to the lesion, places permanent ink marks at the edges of the aperture at its contact with skin to make sure the patient has not moved, takes a single mammogram image, and leaves the breast in compression. The mammogram should show the lesion within the open aperture. The radiologist determines the coordinates of the lesion on the mammogram and, with the patient still in compression, marks this location in ink on the patient’s skin, cleans the skin, and injects a local anesthetic on the ink mark.

The radiologist then passes a needle parallel to the chest wall into and through the lesion. To ensure that the needle path is straight, the radiologist should check that the shadow from the needle hub lies directly over the needle shaft during insertion. After the radiologist passes the needle deep enough into the breast to pass through the lesion, the technologist takes a mammogram to ensure that the needle shaft projects over the lesion.

Once the radiologist confirms that the needle is through the lesion, he or she holds the needle deep in the breast; the technologist releases compression and takes an orthogonal mammogram with the needle still in place. The radiologist reviews the orthogonal mammogram and adjusts the needle depth so that the needle tip is just through the lesion. Blue dye, if used, and a hookwire are inserted.

Stereotactic Guidance

With this technique, the radiologist localizes the lesion under stereotactic guidance, as described for stereotactic core biopsy later in this chapter. The radiologist places a needle into the breast, obtains stereotactic views to make sure the needle is in the middle of the lesion, may inject blue dye, and inserts the hookwire. The patient is removed from the stereotactic device and undergoes standard orthogonal mammograms. The usual problem with stereotactic wire placements is adjusting the depth of the needle in the z-axis.

Ultrasound Guidance

Real-time hand-held ultrasound units with a small transducer provide guidance for preoperative needle localization for ultrasonographically detected breast lesions (Fig. 6-3). To do the localization, the patient is placed in the supine position and the radiologist plans the needle path to the lesion. The radiologist rolls or angles the patient on the table until the needle path is directed safely away from the chest wall to prevent pneumothorax. Using sterile technique and under direct ultrasound visualization, the radiologist anesthetizes the skin and inserts a longer needle for deep anesthesia, keeping the entire shaft of the needle, the needle tip, and the target in the same plane. The anesthesia needle can be used as a “trial run” to judge the safety of the needle path and the difficulty of needle insertion. Then the radiologist inserts the preoperative localization needle into the lesion under real-time ultrasound guidance. Blue dye, if used, and a hookwire are inserted.

Figure 6-3 Ultrasound-guided needle localization. Craniocaudal (CC) (A) and spot compression mediolateral (ML) (B) mammograms show a mass in the medial portion of the breast that was solid on ultrasound, and excisional biopsy was requested by the patient. C, Ultrasound was used to guide a needle into the mass for preoperative localization; the image shows the needle tip in the middle of the mass. After hookwire deployment, CC (D) and ML (E) mammograms show the hookwire tip in the mass. The films were marked with a white grease pen to show the skin outline and skin entry, and an X was placed on the skin over the mass marked with two BBs. F, The specimen radiograph shows inclusion of the mass and the hookwire. Histologic examination revealed a fibroadenoma.

At this point, some facilities place skin BBs before the postwire localization mammogram is obtained. A skin BB may be placed at the wire skin entry site. In addition, the radiologist may place two skin BBs and an indelible ink X over the skin where the lesion lies for the surgeon to see when the patient arrives in the operating room. The technologist then takes a mammogram with the ultrasound-placed wire within the breast.

In some facilities, radiologists or surgeons perform intraoperative ultrasound to direct the breast biopsy.

Specimen Radiography

The needle localization procedure is not over until the specimen radiograph is taken by the technologist and reviewed by the radiologist. The radiologist reports whether the specimen contains the entire lesion, how far the lesion is away from the specimen edge, if the lesion was transected, and whether the hookwire, hookwire tip, and any markers are included (Box 6-3). The radiologist then calls these findings to the surgeon in the operating room. If the lesion is not in the specimen, the radiologist directs the surgeon to the expected location by using landmarks in the excised tissue and on the mammogram and waits for a second specimen (Fig. 6-4). If subsequent specimen radiographs still do not contain the lesion, the surgeon may close the breast and obtain a mammogram to determine whether the targeted lesion is still in the breast. The mammogram is usually done a few weeks after the biopsy.

Figure 6-4 Importance of specimen radiography. The hookwire films from a freehand localization show the tip of the hookwire in microcalcifications on the craniocaudal (A) and mediolateral (B) views. C, The first specimen shows the hookwire but no calcifications. These findings were reported to the surgeon in the operating room. D, Calcifications are seen in the second specimen.

Tissue excised at ultrasound-guided preoperative localizations also undergoes specimen radiography, even if the finding cannot be seen on mammogram. The specimen radiograph may or may not show the ultrasound-localized finding, but will show if the entire hookwire or its tip, as well as any metallic markers, was excised. If the specimen radiograph does not show the ultrasound-localized finding, the radiologist can perform specimen ultrasound to see if the tissue contains the mass (Figs. 6-5 and 6-6).

Figure 6-5 Ultrasound-guided preoperative needle localization with specimen radiography. In an 18-year-old woman, ultrasound-guided core biopsy of an oval mass in the 6-o’clock position showed pathology suggestive of fibroadenoma versus phyllodes tumor. A marker was placed in the mass. The surgeon requested ultrasound-guided preoperative needle localization. A, The ultrasound shows the bright speckle inside the mass (arrow), representing the marker placed at the time of the core biopsy. This patient then underwent ultrasound-guided preoperative needle localization for excisional biopsy. B, Ultrasound shows the needle within the mass just before wire placement for ultrasound-guided preoperative needle localization. C, Ultrasound shows the wire tip (arrow) in the mass after wire placement through the needle. D, Mammogram after ultrasound-guided needle localization shows the hookwire near the marker in the mass, which is obscured by surrounding dense breast tissue. E, After excisional biopsy, the specimen radiograph shows inclusion of the hookwire, dense tissue, and the marker. Just as on the mammogram, the mass is invisible. F, Ultrasound of the breast specimen shows inclusion of the mass previously seen within the patient. The surgeon was called in the operating room to confirm that he had removed the mass, marker, hookwire, and hookwire tip. Pathology showed fibroadenoma.

Figure 6-6 Ultrasound-guided bracket needle localization. A, Positron emission tomography/computed tomography (PET/CT) shows a mass in the right breast on the CT scan (arrow). B, The mass demontrates increased uptake of fluorodeoxyglucose on the PET scan. C, Ultrasound shows a palpable lobulated, hypoechoic, suspicious mass in the 12-o’clock position on the right breast in transverse plane, corresponding to the mass seen on PET/CT. D, The mass is slightly wider in its caudal aspect. Core biopsy showed cancer. Because the mass was difficult to see against the dense breast tissue on the mammogram, the surgeon requested ultrasound bracket localization. E, Ultrasound bracket localization shows the needle at the medial aspect of the mass (arrow). F, A second wire can be seen in the lateral aspect of the mass (arrow). G, Lateral-medial mammogram after localization shows the two wires at either end of the mass (the mass is difficult to see against the dense tissue). Use of the open aperture of the alphanumeric plate avoids pushing the wires further into the breast. Annotations show clusters of three and four BBs marking the skin entry sites. Single and double BBs show the medial and lateral aspects of the mass, marked by an X written on the skin to help the surgeon find the mass in the operating room. H, Annotated magnified craniocandal view shows the wires next to the mass. Annotations show clusters of three and four BBs marking the skin entry sites. Single and double BBs show the medial and lateral aspects of the mass, marked by an X written on the skin to help the surgeon find the mass in the operating room. I, A specimen radiograph shows inclusion of the mass and the two hookwires. Note that one of the wires no longer inside the specimen was placed within the container to show that it and its tip were removed. J, The same specimen photographed at lighter contrast shows the letters and numbers on the container. The mass is located at coordinates F.0/4.0. K, An ultrasound of the breast specimen shows inclusion of the entire mass scanned at coordinates F.0/4.0, showing that the entire mass and its margins were removed.

Pathology Correlation

Later, the radiologist reviews the pathology report to see if the pathology reflects what the radiologist expected, based on the lesion’s imaging characteristics. Radiologic–pathologic correlation ensures that the targeted lesion analyzed at pathologic evaluation is concordant with the imaging finding and, specifically, that the pathology report describes a histologic finding that is known to correlate with the imaging findings. For example, if the targeted lesion shows fine pleomorphic calcifications, a diagnosis of malignancy, high-risk lesion, or benign lesion would all be concordant if the targeted calcifications were definitely seen in the specimen radiograph and preferably also on the pathology slides (Fig. 6-7). If the pathology report showed an uncalcified fibroadenoma when the targeted radiographic finding was fine pleomorphic calcifications, the pathologic–radiologic correlation would be discordant, and the case would warrant additional investigation.

Figure 6-7 A, Magnification mammogram shows invasive ductal cancer (IDC) and ductal carcinoma in situ (DCIS) as a mass and calcifications previously sampled by stereotactic biopsy. The magnified craniocaudal mammogram shows a spiculated mass, residual calcifications, air, and a metallic marker. This area was localized for surgical excisional biopsy. B, After preoperative localization and excisional biopsy, magnified, cropped specimen radiograph shows the hookwire, hookwire tip, marker, the mass, and calcifications. The uncropped specimen radiograph (not shown) showed that the entire mass and calcifications were removed. Because IDC and DCIS had been shown by stereotactic core biopsy, the radiologist expects IDC, DCIS, and calcifications in the pathology report. Pathology showed IDC, DCIS, calcifications, and postbiopsy change, which was concordant with imaging.

Pathologic–radiologic correlation of targeted calcifications is a special subset of breast biopsy correlation. Calcifications from targeted calcifications must be seen on the surgical specimen radiograph for the biopsy to be concordant. Calcifications seen just on histologic slides and not on the specimen radiograph do not represent the calcified lesion being targeted and are not concordant. Calcifications seen on the specimen radiograph are usually seen on pathology slides, but the pathologist may not see them for several reasons.

First, the calcifications may be calcium oxalate and are seen on the slides. Unlike calcium phosphate calcifications, which are easily seen on hematoxylin and eosin (H&E) staining, calcium oxalate is not visualized with H&E staining and requires a special polarized light to show the calcifications.

Second, the calcifications may be in the paraffin blocks. During specimen processing, thin breast tissue samples are embedded in paraffin blocks, which are then sliced and placed on slides for staining. Each block is several millimeters thick, but each slide contains only micromillimeters of paraffin and tissue. The calcifications may still be in the block and may never have been placed on a slide for review. A radiograph of the blocks may show the calcifications, and re-sectioning of that particular block will show the calcifications (Fig. 6-8).

Figure 6-8 Tissue specimen radiography in pathology department. A, Radiograph of six tissue specimens sectioned from an excisional breast biopsy performed for calcifications. Calcifications are found in all six specimens. B, Magnified view of two tissue specimens containing calcifications (arrows). C, Pathology technologists place the tissue pieces in paraffin in a plastic tissue cassette. This paraffin block radiograph shows the calcifications (arrows) from the two tissue specimens shown in part B. Pathology showed fibrocystic change and calcifications. If the slides from this cassette did not show calcifications, the pathologists would have taken additional samples from this cassette.

(Images courtesy of Dr. Gerald Berry, Stanford University, Palo Alto, CA.)

Third, other calcifications may be removed from the specimen if the microtome cutting device that slices the tissue/paraffin block for slides pushes large calcifications out of the specimen at the time of sectioning.

If the targeted calcifications seemed to be present in the specimen radiograph but no calcifications are found in the pathology slides or in the paraffin blocks, a repeat mammogram can determine whether the calcifications are still in the breast and were not removed at surgery. Rarely, the calcifications seen in the specimen radiograph can be incidental calcifications and not the ones that were targeted.

Needle Types

The types of biopsy needles used for specific breast lesions and guidance methods vary around the world. A trend toward progressively larger needles and more tissue samples per biopsy site has been noted, especially in the United States. Three main types of needles are used for percutaneous biopsies (Table 6-1). Fine-needle aspiration (FNA) needles, usually 25- to 20-gauge, are used for cyst aspirations and for solid breast masses. The aspirated material requires interpretation by expert cytopathologists. FNA is usually done with ultrasound or palpation guidance with at least four needle passes. FNA is less commonly done in the United States compared to Europe and Asia.

Table 6-1 Needles Used for Percutaneous Breast Biopsies

Automated large-core (core) needles in 18- to 14-gauge (Fig. 6-9A and B) commonly are used to biopsy masses with ultrasound or palpation guidance. In some facilities, especially outside the United States, core needles are used with stereotactic guidance to biopsy masses or calcifications. An automated large-core biopsy needle obtains a single specimen with each pass of the needle, and 2 to 12 specimens are obtained by firing the needle multiple times. Pathologists who are comfortable interpreting surgically excised breast biopsy tissue can interpret the histologic material obtained.

Figure 6-9 Needle types and coaxial guide for core needle biopsy. A, Schematic of core biopsy needle parts showing the needle, coaxial sheath, and inner stylet. B, Schematic of how to use a multifire core biopsy needle for breast biopsies. The outer cutting cannula shoots over the trough and cuts the mass. The entire needle is removed each time. C, Schematic of a vacuum-assisted probe for needle core biopsy. The outer cutting cannula shoots over the trough and cuts the mass. The vacuum transports the specimen to the needle end for removal. There may be one or multiple insertions, depending on the vendor.

Directional vacuum-assisted (vacuum) needles (see Fig. 6-9C) are available in 7- to 14-gauge and are used for stereotactic, ultrasound-guided, and MRI-guided biopsies. Depending on the manufacturer, vacuum biopsy can be done with just one needle pass, and multiple specimens are obtained by rotating the collection aperture of the needle to obtain between 6 and 18 specimens. Other directional vacuum-assisted needles obtain single vacuum specimens with each pass, requiring multiple insertions. In some facilities, vacuum biopsies are used to excise benign lesions such as fibroadenomas to avoid the need for surgical excision or imaging follow-up, once the fibroadenoma has been diagnosed by core needle biopsy and adequate sampling.

Both single-insertion and multi-insertion needles can be used with or without a coaxial guide (Fig. 6-10A). The coaxial guides are usually used with ultrasound or MRI guidance. The purpose of the coaxial guide is to provide a path to the target that the radiologist can use again and again without retraumatizing the breast tissue. The coaxial device consists of an inner sharp stylet and an outer sheath. The coaxial device is placed through the tissue so that the stylet tip/sheath edge is at or in the lesion. Then the radiologist removes the stylet, leaving a sheath that provides a “tunnel” through the breast tissue directly to the lesion. The radiologist then places the biopsy needle through the sheath into the lesion and takes samples. The radiologist can repeatedly place the biopsy needle through the sheath without having to disturb the surrounding breast tissue. Coaxial biopsies can be done with the sheath near the mass or through the mass (see Fig. 6-10B).

Figure 6-10 A, Schematic of how to use a coaxial sheath next to a mass for ultrasound-guided core biopsies. The radiologist places a coaxial containing a sharp, inner stylet through the breast tissue next to a mass. The radiologist removes the stylet, places a core biopsy needle through the coaxial sheath, fires the needle through the mass, and withdraws the needle. The coaxial sheath is left adjacent to the mass, providing a tunnel through the breast tissue. The radiologist removes the specimen from the needle and can replace the needle through the coaxial sheath for the next core. B, Schematic of how to use a coaxial sheath inside a mass for ultrasound-guided core biopsies. The radiologist places a coaxial containing a sharp, inner stylet into a mass. The radiologist removes the stylet, places an open core biopsy needle through the coaxial sheath, withdraws the coaxial to expose the biopsy trough inside the mass, and fires the needle to take the sample. Before withdrawing the biopsy needle, the radiologist threads the coaxial sheath over the fired needle and leaves the sheath inside the mass. The core biopsy needle can now be replaced into the sheath to take the next sample.

Cyst Aspiration

Masses on mammograms often prompt requests for breast ultrasound and cyst aspiration. To do a cyst aspiration the radiologist advances a fine needle into the cyst by palpation or image guidance. If the cyst is tense, fluid wells up into the needle hub. To aspirate the cyst, the radiologist attaches a syringe to the needle and draws fluid into the syringe until no more fluid can be obtained. Cyst aspiration can be done by ultrasound (Fig. 6-11) or, less commonly, by x-ray guidance using a fenestrated compression plate and mammography. If cyst aspiration is done under ultrasound, the radiologist should be able to watch the cyst disappear in real time.

Figure 6-11 Cyst aspiration. A, Ultrasound shows a needle in a cyst near an implant. B, The follow-up ultrasound shows that the cyst is gone.

Aspirated fluid is sent for cytologic evaluation only if an intracystic mass is present or the fluid is bloody. A large series of cyst aspirations by Tabar and colleagues showed that cyst fluid cytology is often falsely negative, even in the presence of an intracystic mass. In these cases, the pneumocystogram was enough to diagnose an intracystic mass and prompt biopsy of the rare intracystic cancer.

Pneumocystograms are mammograms obtained after the radiologist injects air into a cyst cavity. The pneumocystogram shows the air-filled cyst cavity on the mammogram, enabling the radiologist to make sure that a mass prompting biopsy on the mammogram corresponds to the aspirated cyst and to exclude an intracystic mass. Air is thought to be therapeutic in preventing cyst recurrence (Fig. 6-12). To do a pneumocystogram, the radiologist aspirates the cyst first. Once the fluid has been aspirated completely, the radiologist disengages the syringe while carefully holding the needle tip in the decompressed, flattened cyst cavity. The radiologist attaches an air-filled syringe to the needle, injects a small amount of air into the cyst cavity, takes the needle out, and obtains CC and mediolateral mammograms immediately. A normal pneumocystogram should show an air-filled, thin-walled, round or oval cavity without intracystic solid masses or mural nodules.

Figure 6-12 Pneumocystogram. A, A craniocaudal (CC) mammogram shows an oval breast mass in the inner portion of the breast. B, Ultrasound shows a complicated cyst versus a solid oval mass. After cyst aspiration under ultrasound guidance, air was placed in the cyst cavity. CC (C) and lateral (D) pneumocystogram mammograms show air (arrows) replacing fluid in the mass, which confirms that the finding on the mammogram represents a cyst that was aspirated.

Although radiologists can usually tell if a cyst on ultrasound corresponds to a specific mammographic mass, this correlation can be tricky. When the correlation is unclear and the radiologist has chosen not to do a pneumocystogram, the radiologist orders a postaspiration mammogram to see if the “cyst” disappears. The mass should be gone on the postaspiration mammogram if the aspirated cyst is the mammographic mass. If the mass still shows on the postaspiration mammogram, the mammographic finding is separate from the cyst and needs further investigation (Fig. 6-13).

Figure 6-13 Correlating mammography and ultrasound after cyst aspiration. Right mediolateral oblique (MLO) (A) and craniocaudal (CC) (B) views show a possible mass on screening mammography (circles). C, Ultrasound shows a probable multiseptated, complicated cyst in the expected location of the mammographic mass. D, Fine-needle aspiration under ultrasound shows the needle in the mass. E, Cyst fluid was aspirated and the mass disappeared. Postaspiration MLO (F) and CC (G) views show that the mammographic mass disappeared, indicating that the ultrasound and mammographic findings represented the same simple cyst.

Palpation Guidance

FNA or core biopsy can be performed on palpable masses. With this method, CC and mediolateral mammograms and other imaging studies are reviewed. Palpation-guided procedures are similar to ultrasound-guided procedures, but there is no visualization of the lesion or needle during the procedure. The lesion must be discretely palpable and well away from the chest wall for the biopsy to be done with accuracy and safety. This procedure is usually reserved for cysts and solid masses that are almost definitely malignant or benign by imaging and palpation criteria.

Ultrasound Guidance

When compared with stereotactic biopsy, ultrasound-guided biopsy has the advantage of using readily available equipment and is fast and cost-effective. The first step in ultrasound-guided biopsy is to find the questioned lesion for biopsy. This commonly occurs when a mass on the mammogram prompts an ultrasound to further characterize the mass and localize it for biopsy. When correlating the mammogram to the ultrasound, the mass can be far away from the chest wall on the mammogram and lie next to the pectoralis muscle on the ultrasound. This occurs because the breast tissue is compressed far away from the chest wall when the patient stands up for the mammogram. On ultrasound, the breast falls dependently onto the chest wall when the patient lies down (Fig. 6-14A).

Figure 6-14 Schematics of how masses appearing to be far away from the chest wall on mammography may be found near the chest wall on ultrasound and how to keep the needle tip away from the chest wall on ultrasound-guided core biopsy A, Schematic mammograms show a mass in the upper inner quadrant that appears to be far from the chest wall. However, mammograms are obtained with compression; when the patient lies supine, the mass falls dependently against the chest wall. On ultrasound, the mass may be closer to the chest wall than expected from the mammogram. B, With superficial lesions, the needle tip and throw are usually far away from the chest wall. C, With deeper lesions, the needle angle is steeper, and the radiologist judges whether the needle “throw” will penetrate the lung. D, When the patient is flat and the lesion is even deeper, the needle trajectory can point toward the chest wall. E, To change the needle trajectory, the patient can be angled so that her chest wall parallels the needle track/throw. F, Injecting anesthetic underneath the lesion can lift it away from the chest wall for biopsy. G, Inserting the needle tip into the lesion and redirecting the throw of the needle avoids placing the needle tip into the chest wall.

(B to G, Courtesy of Dr. Sunita Pal, Stanford Radiology, Stanford, CA.)

When planning ultrasound-guided needle biopsies, it is important to keep the needle tip away from the chest wall to prevent pneumothorax. Unlike upright preoperative x-ray–guided needle localization or prone stereotactic localization, the ultrasound-guided biopsy is done supine and the needle is not necessarily parallel to the chest wall. Further complicating matters, some core biopsy needles “throw” the cutting trough 2.5 cm further into the tissue beyond the needle tip. Thus, planning a safe ultrasound-guided needle biopsy trajectory must take into account both the needle tip and the needle “throw” trajectory. To plan a safe procedure, the radiologist rolls the patient on the table so that the needle trajectory is as parallel to the chest wall as possible and not at a steep angle aiming toward the lungs. Patient positioning can take some time, but it is worth the few minutes to position the patient accurately to avoid an untoward complication. Another way to keep the needle away from the chest wall is to inject anesthetic underneath the targeted mass to lift it away from the pectoralis muscle. Alternatively, in some cases, the radiologist can stick the biopsy needle tip into the mass and lift it into a safer trajectory before firing the needle (see Fig. 6-14B to G).

For ultrasound-guided FNA, the radiologist introduces a needle in the plane of the transducer axis to show the entire shaft of the needle, its tip, and the lesion. Once the needle is within the lesion, the radiologist aspirates the mass with a vigorous to-and-fro movement to obtain material for cytologic evaluation and then withdraws the needle. At least four passes should be performed; optimally, the material should be analyzed immediately to ensure that adequate cellular material has been obtained for diagnosis. After aspiration, direct pressure is applied to the site (Fig. 6-15).

Figure 6-15 Fine-needle aspiration of axillary lymphadenopathy in a patient with invasive ductal cancer. A, Initial ultrasound shows a large invasive ductal cancer in the upper left breast undergoing ultrasound-guided core biopsy. B, Ultrasound of the left axilla in this patient shows a lymph node with an enlarged, thickened cortex, suspicious for metastatic disease. C, Fine-needle aspiration under ultrasound guidance shows the needle tip in the lymph node cortex (arrow). Cytology showed lymph node metastases. D, In another patient, the right axillary lymph node has an irregular, thickened cortex and a compressed fatty hilum. E,

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