What are the available imaging modalities for IPNB?
Image guidance for percutaneous needle biopsy is provided to precisely localize a lesion that is not palpable and, therefore, requires imaging for localization. IPNB can be performed using fluoroscopy, ultrasonography (US), computed tomography (CT), or magnetic resonance imaging (MRI), and the use of these modalities is dependent on the target organ, the type of lesion, and patient parameters. Lesions that can be easily seen on a radiograph may be biopsied fluoroscopically, including large lung lesions and some bone lesions. To ensure proper needle placement, fluoroscopic equipment must be able to provide complex angle imaging. Fluoroscopy is less desirable due to increased radiation exposure to personnel during the procedure. Its use for lung biopsies has decreased over time, as CT is able to detect and provide needle guidance of small lung lesions.
US is perhaps the most versatile modality for IPNB. It is a safe and accurate method that uses real-time imaging to guide needles into abdominal and pelvic organs and masses. It is also typically used to sample thyroid and breast lesions. Its advantage over CT-guided biopsies is that it can be done portably, is less expensive, and does not use ionizing radiation. However, some lesions are not visualized sonographically because of size or location. US is typically used to sample lesions within superficial lymph nodes, liver, and kidneys, but has little role in sampling lesions in the chest unless the lesion is in the pleura or chest wall.
CT allows for biopsy of lesions not seen fluoroscopically or sonographically and provides the most accurate visualization of anatomy for accurate and safe access to lesions, avoiding transgression of vital structures. It is used for sampling of lesions in the neck, lung, pleura, mediastinum, abdomen, and pelvis, including deep retroperitoneal and pelvic lymph nodes.
Some lesions can only be visualized by MRI, which can also be utilized on rare occasion. MRI has limited use because of expense, difficulty in accessing the patient within the magnet, and difficulties with use of ferromagnetic instruments within the magnetic field.