Location Of Carotid Artery

Figure 5.8. Axial CT image shows a left parapedicular approach (arrow) used to sample this destructive vertebral body lesion.

Fungal Osteomyelitis Images
Figure 5.9. Axial CT image shows a right transcostovertebral approach (arrow) used to sample this destructive vertebral body lesion (fungal osteomyelitis).
Vertebrae Fungus Disease

Figure 5.10. Steps in a CT-guided biopsy. (A) To use a right transpedicular approach (long black arrow), the skin entry site must be located near the second skin marker (white arrow). (B) The guide needle is advanced to the posterior margin of the pedicle (arrow).

Figure 5.10. Steps in a CT-guided biopsy. (A) To use a right transpedicular approach (long black arrow), the skin entry site must be located near the second skin marker (white arrow). (B) The guide needle is advanced to the posterior margin of the pedicle (arrow).

Bone Biopsy

Figure 5.10. Continued. (C) The bone biopsy needle is advanced through the pedicle to sample the right-sided lytic lesion (arrow).

Figure 5.10. Continued. (C) The bone biopsy needle is advanced through the pedicle to sample the right-sided lytic lesion (arrow).

the entry site on the skin surface is marked with an indelible ink marker. The region of interest is then prepped and draped in sterile fashion. A 1 cm wheal is raised at the skin entry site by using a 25-gauge needle and a local anesthetic agent (e.g., 1% lidocaine, 0.25% bupivacaine). A #11 scalpel blade is used to make a dermatotomy incision at the skin entry site. A stylet-bearing thin needle is then advanced by means of image guidance, and the local anesthetic is then administered into the deeper soft tissues. If a vertebra is to be entered, infiltration of the anesthetic agent into the periosteum is extremely helpful in minimizing patient discomfort. With coaxial technique, the position of the needle tip relative to the lesion is adjusted and confirmed by means of image guidance. When the needle tip is in satisfactory position, the needle hub is removed and the needle then essentially serves as a stiff guidewire. A guiding cannula is inserted over the hubless needle and advanced to the desired level under image guidance. Aspiration or core needles can be passed through this guiding cannula to obtain specimens.

The needle tip must always be accounted for with respect to the target lesion and to all pertinent critical structures (Figure 5.11). This rule applies especially to cutting needles whose biopsy chamber requires additional exposure and excursion within the lesion matrix to enable the cutting portion of the needle mechanism to slide over the biopsy chamber and retrieve the specimen. Moreover, specimen retrieval by n i)T"5a

Figure 5.11. Axial CT image obtained during a bone biopsy shows a guide needle that reaches the anterior vertebral body cortex (large arrow). Note the proximity of this needle to the aorta (arrowhead). The guide needle had been advanced far beyond the target lesion (small arrow).

means of fine-needle aspiration requires an in and out motion within the lesion matrix. Failure to completely account for the position of the needle tip may result in an unsuccessful biopsy, and may also injure a critical structure. To access bone marrow or a lytic lesion with an aspiration or cutting needle, a preexisting bone window must be present within the vertebral cortex, as occurs with a lytic focus, or a cortical window must first be cut with a bone needle. Neither aspiration nor cutting needles will penetrate normal or near normal bone cortex.

Cervical spine biopsy often requires an anterolateral approach.14 The neck can be separated into suprahyoid and infrahyoid compartments (Figure 5.12). The location of the carotid space contents within these compartments and the location of the spinal lesion will determine the skin entry site for the biopsy (Figure 5.13). Other important structures that are to be avoided include oropharynx, hypopharynx, and visceral space contents (esophagus, trachea, thyroid gland). In approaching lower cervical spine lesions, care must be taken to avoid the pulmonary apex. In addition to being constantly aware of the location of the carotid artery and jugular vein, the operator must be cognizant of the location of the vertebral artery. When in doubt about the location or identity of a potentially important vascular structure, administer an intravenous contrast agent to clarify the situation.

The trajectory can be anterior or posterior to the carotid space, depending on the location of the great vessels. A 22-gauge needle can be used to go safely beside these structures with CT guidance. Alterna-

Carotid Space
Figure 5.12. Location of the prevertebral and paravertebral spaces within the suprahyoid (A) and infrahyoid neck (B). Note the anterolateral position of the carotid space (arrows) relative to the prevertebral space.
Infrahyoid Mass

Figure 5.13. Steps in a CT-guided biopsy of the cervical spine. (A) Skin markers (a set of four taped 18-gauge 1 in. needles) are placed for an anterolateral approach with the patient in the supine position. The soft tissue window algorithm is used to identify the carotid artery (arrow) and internal jugular vein (arrowhead). (B) Coaxial technique is used to advance a needle with a removable hub, through a short 18-gauge needle, past the carotid artery (white arrow) and adjacent to the abnormal cervical vertebra (black arrow).

Figure 5.13. Steps in a CT-guided biopsy of the cervical spine. (A) Skin markers (a set of four taped 18-gauge 1 in. needles) are placed for an anterolateral approach with the patient in the supine position. The soft tissue window algorithm is used to identify the carotid artery (arrow) and internal jugular vein (arrowhead). (B) Coaxial technique is used to advance a needle with a removable hub, through a short 18-gauge needle, past the carotid artery (white arrow) and adjacent to the abnormal cervical vertebra (black arrow).

Gauge Needles

Figure 5.13. Continued. (C) A bone cannula is safely advanced over the wire. A trephine needle (arrow) is advanced into the substance of the vertebral body to obtain a core of bone.

Figure 5.13. Continued. (C) A bone cannula is safely advanced over the wire. A trephine needle (arrow) is advanced into the substance of the vertebral body to obtain a core of bone.

tively, some operators prefer to use palpation and carotid displacement during the initial needle placement, to bypass the carotid artery. This maneuver is often performed with fluoroscopy-guided biopsy procedures. Once the needle tip has passed beyond the carotid space and is near the target, a coaxial technique can be used to safely obtain multiple biopsy specimens. A posterior approach is occasionally required for accessing posterior element lesions. Given the relatively small size of the posterior elements and the proximity to the spinal cord, it is advisable to utilize CT for safely approaching and sampling lesions in this location.14a

For thoracic or lumbar spine lesions, a transpedicular approach is optimal for accessing centrally located vertebral body lesions (Figure 5.14). The pedicle provides a safe passageway to the vertebral body. Special care must be taken to avoid fracturing the pedicular cortex. This complication can cause either direct injury to the spinal cord or exiting nerve root, or can indirectly injure these structures by leading to hematoma formation. The margins of the pedicle should be visualized at all times while the biopsy needle courses through the pedicle. A potential pitfall of the transpedicular approach, which occurs when the pedicle is not involved by tumor, is the possibility of obtaining a false negative biopsy result. The solution in such cases is to take deeper and multiple samples.

The transcostovertebral approach is useful in accessing laterally located thoracic vertebral lesions or in sampling the thoracic disc.12 The

Guided Biopsy Thoracic Spine

Figure 5.14. Steps in a CT-guided biopsy of the thoracic spine. (A) The patient is in the prone position and skin markers (arrow) are placed to determine the optimal skin entry site. (B) A 1.5 in. 22-gauge needle is used to administer local anesthetic along the biopsy tract to the periosteal surface (arrow). (C) The sequential tandem technique is used to replace the 22-gauge needle with a 12-gauge bone needle, which is gradually advanced through the pedicle (arrow) and into the vertebral body under imaging guidance.

Figure 5.14. Steps in a CT-guided biopsy of the thoracic spine. (A) The patient is in the prone position and skin markers (arrow) are placed to determine the optimal skin entry site. (B) A 1.5 in. 22-gauge needle is used to administer local anesthetic along the biopsy tract to the periosteal surface (arrow). (C) The sequential tandem technique is used to replace the 22-gauge needle with a 12-gauge bone needle, which is gradually advanced through the pedicle (arrow) and into the vertebral body under imaging guidance.

Location Caroted Arteries Body

Figure 5.14. Continued. (C) The sequential tandem technique is used to replace the 22-gauge needle with a 12-gauge bone needle, which is gradually advanced through the pedicle (arrow) and into the vertebral body under imaging guidance.

Figure 5.14. Continued. (C) The sequential tandem technique is used to replace the 22-gauge needle with a 12-gauge bone needle, which is gradually advanced through the pedicle (arrow) and into the vertebral body under imaging guidance.

posterolateral approach is ideal for accessing laterally located vertebral body lesions or their paraspinal soft tissue components or the intervening disc space within the lumbar spine. Two, preferably three, core specimens are obtained and placed in 10% formalin. When bone biopsy cores are obtained, they must undergo a period (approximately 48 hours) of decalcification in 7% formic acid, whereupon the specimens are embedded in paraffin for subsequent histological sectioning and staining. The reported diagnostic accuracy of core biopsy ranges from 77 to 97%.15 If the clinical concern is infection, the specimens are placed in sterile containers and immediately brought to the microbiology laboratory for appropriate processing.

When aspiration biopsy is anticipated, it should be performed prior to obtaining any core specimens, since the core biopsy can create a hem-orrhagic tract that prevents successful aspiration of the desired abnormal tissue.15 Otherwise, a different tract to the lesion must be utilized. Successful aspiration biopsy requires a secure fit between the aspirating syringe and the needle hub to facilitate forceful suction. Full negative pressure is generated by using a 20 mL syringe while the needle is being advanced and retracted within the lesion.16 The distance of the needle excursions depends upon the lesion size; large lesions permit safer, longer excursions, and short excursions are required for small lesions adjacent to critical structures (Figure 5.15). Needle excursions extending more than 3 to 4 mm are required to obtain a specimen.17 Slight adjustments in angulation, when possible, are made with each needle pass to increase the yield of pathological tissue.17

Vertebral Body Image
Figure 5.15. Axial CT image shows a large right paraspinal mass (arrows) that erodes into the lumbar vertebra. The size of this mass permits long excursions of the biopsy needle during fine-needle aspiration.

A flash of hemorrhagic fluid within the needle hub usually signals the end point of aspiration. In the ideal situation, the needle and syringe are withdrawn from the spinal lesion and this ensemble is immediately handed to a cytotechnologist, who prepares slide smears of the specimen. The technologist or a pathologist looks at the slides under a microscope and determines whether abnormal cells are present within the specimen. Alternatively, the biopsy specimen can be placed in 95% ethanol before being sent for cytological analysis. The published accuracy of aspiration biopsy is series dependent and ranges from 23 to 97%.15 When infection is the working clinical diagnosis, the aspirates are not placed in ethanol but instead are submitted in sterile containers to the microbiology laboratory. If fluid cannot be aspirated, a few milliliters of sterile, nonbacteriostatic normal saline can be injected through the biopsy needle and reaspirated for subsequent microbiological analysis. Aspirates obtained following core biopsies can also be sent for microbiological analysis: there is always bleeding at the core biopsy site, so that blood can be aspirated and placed in a sterile container.

Alternatively, the aspiration biopsy can be performed prior to the core biopsy procedure. These two techniques have been shown to be complementary and to increase the diagnostic accuracy of the percutaneous biopsy procedure.15 The histological features of cell structure and microarchitecture may provide a specific cytological diagnosis. A positive fine-needle aspirate can obviate a more aggressive biopsy procedure, thereby reducing the likelihood of a procedure-related complication (Figure 5.16). Furthermore, the core biopsy can also be used to produce a touch preparation for immediate cytological analysis.18 These procedures in combination can minimize the possibility of obtaining a specimen too small for analysis. A spine biopsy procedure may be discontinued when a positive aspirate is identified by the cy-topathologist, or when a set of three fine-needle aspirations and three

Needle Biopsy Spine

Figure 5.16. Intraspinal biopsy. Fine-needle aspiration technique was used to sample (A) a cystic astrocytoma (arrow) of the spinal cord and (B) a solid as-trocytoma drop metastasis within the lumbar spinal canal (arrow).

Figure 5.16. Intraspinal biopsy. Fine-needle aspiration technique was used to sample (A) a cystic astrocytoma (arrow) of the spinal cord and (B) a solid as-trocytoma drop metastasis within the lumbar spinal canal (arrow).

bone and/or soft tissue cores has been obtained. Other factors, such as small lesion size, limited lesion access, or the occurrence of a complication may require discontinuation of the biopsy procedure at the discretion of the operator.

Specific instances do occur in which percutaneous biopsy may be unsuccessful, yielding either no specimen or one that proves to be non-diagnostic. The bony elements of the vertebrae consist of round, hard surfaces. Securing purchase on their normal hard cortex can be difficult when the target lesion lies deep to normal bone. Sclerotic or os-teoblastic lesions can be quite difficult to sample (Figure 5.17).7 At the other end of the lesion spectrum are heterogeneous lesions that are predominantly either cystic or necrotic. Despite multiple attempts, it may not be possible to harvest a satisfactory specimen from these lesions. Lesions with variable histology from one area to another, such as cartilaginous tumors, can also cause a diagnostic dilemma. Fortunately, these diagnostic challenges are infrequent. More often, one is unable to retain a specimen within the bone biopsy needle chamber after successful entry into the substance of an osseous lesion. Several maneuvers can be attempted to obtain a specimen. Slight, gentle rocking of the needle may allow separation of the specimen from the parent bone. If the lesion is large enough and there is a margin of safety, then advancing the biopsy needle slightly may enable retention of the bone core within the chamber of the biopsy needle. Applying suction to the biopsy needle with a 20 mL syringe may also facilitate a successful biopsy. Some single-pass bone biopsy needles come with an inner can-nula that is partially truncated near its tip to trap the bone core within the parent needle chamber. Alternatively, if the sample size remains unsatisfactory for diagnostic purposes, a larger gauge needle system such as the Craig system can be used to obtain a specimen (Figure 5.18).

Other reasons for a nondiagnostic result include biopsies that are limited either by small lesion size or because too few passes were made with the biopsy needle. Hypervascular lesions can be difficult to sample, since the brisk bleeding that can potentially occur with the initial access to the lesion can terminate the procedure. The intraosseous blood that is often aspirated during bone biopsy is sometimes erroneously discarded. This osseous blood should be considered to be a biopsy specimen and submitted for pathological analysis, since it is possible to diagnose malignancy from this tissue.19 Occasionally, a discrepancy in accounting for vertebral levels between different modalities causes the wrong vertebral levels to be sampled. Many spine lesions are identified on MRI, yet the percutaneous biopsy procedure is performed either with fluoroscopy or with CT. In certain situations, lesion con-spicuity may be so much decreased with the latter modalities that optimal sampling is compromised. With respect to infectious spondyli-tis, the common reason for a nondiagnostic biopsy result is that patients are already being treated with antibiotics at the time of the procedure. Other reasons for a nondiagnostic biopsy result in spine infection include a failure to perform the correct microbiological testing, such as not performing an acid-fast bacillus stain or culture, dismissing as contaminants unusual microbes that may in fact be the

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Responses

  • magnus
    Is the veterbral artery located near the surface of the skin?
    7 years ago
  • Medhane
    Where is the carotid artery located on the body?
    7 years ago
  • sinikka
    Where is the vertebral artery located?
    7 years ago
  • PATRICK
    Where is located carotid vertrebral?
    7 years ago
  • paciano
    What are the functions of the vertebral arteries?
    6 years ago

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