Image-guided biopsy: the right sample before the right treatment

Many biopsies begin with a finding: a nodule on a scan, an abnormal result on a checkup. According to RadiologyInfo.org — the patient information site of the Radiological Society of North America (RSNA) and the American College of Radiology (ACR) — when imaging cannot clearly define an abnormality, a biopsy may be necessary. Biopsies are often used to diagnose cancer, but also infections and inflammatory and autoimmune conditions.

The National Cancer Institute (NCI) puts it plainly: a biopsy is often the only way to tell for sure whether a finding is cancer. A pathologist examines the sample and writes a pathology report, and the details in that report can help show which treatment options might work.

That is the diagnosis-first idea in its most concrete form. Treatment decisions rest on the report. The report rests on the sample.

Interventional radiology (IR) is a medical specialty that uses imaging — X-ray, fluoroscopy, computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound — to pinpoint a problem and guide minimally invasive procedures in real time, according to the Society of Interventional Radiology (SIR). Biopsy is among the procedures SIR lists. See the image-guided procedures we coordinate in Los Cabos.

In an image-guided needle biopsy, the doctor passes a needle through the skin (percutaneously) to the abnormal area, using imaging to decide exactly where it goes. RadiologyInfo.org notes that these procedures are most often performed by a specially trained radiologist, interventional radiologist, or neuroradiologist. (IR also covers image-guided pain procedures — a topic for another issue.)

Not every biopsy is image-guided through the skin. NCI also describes biopsies taken during endoscopy — for example, during a colonoscopy — and during surgery. The right route depends on where the finding is.

The limit: the abnormality has to be visible with the chosen method, so the radiologist uses the guidance best suited to the area, RadiologyInfo.org notes.

Image guidance has also changed where samples are taken. In a randomized trial published in the New England Journal of Medicine in 2018, men with suspected prostate cancer who had MRI first — followed by biopsy aimed at the suspicious areas MRI showed — were diagnosed with clinically significant cancer in 38% of cases, compared with 26% for standard ultrasound-guided biopsy without prior MRI. In the MRI group, 28% of men had MRI results not suggestive of cancer and did not undergo biopsy. The MRI target could be mapped onto live ultrasound visually or with software, often called MRI–ultrasound fusion. The findings apply to that setting; the broader lesson is that better targeting starts before the needle does.

A biopsy can be technically successful and still not answer the question. SIR’s quality standards separate two ideas: diagnostic yield (the share of biopsies that result in a diagnosis) and sample adequacy (whether the sample contains enough material for a diagnosis to be made).

A best-practice guide from the National Lung Cancer Roundtable, published in CA: A Cancer Journal for Clinicians, lists common reasons a biopsy is nondiagnostic: the sampled site did not contain the disease, the target was hard to sample during the procedure, the sample held too few tumor cells, or the lesion contained extensive necrosis (dead tissue). The guide notes that a nondiagnostic biopsy sets back the entire path from diagnosis to treatment.

Several of those reasons come down to targeting — choosing the most informative lesion, and the most informative part of it. SIR also describes rapid on-site evaluation, in which a cytopathologist checks FNA samples during the procedure to confirm needle placement and likely adequacy; availability varies.

A nondiagnostic result usually means another procedure. For thyroid nodules, for example, the 2023 Bethesda System for Reporting Thyroid Cytopathology recommends repeating a nondiagnostic FNA with ultrasound guidance, which yields a diagnostic result in 60%–80% of cases. A repeat often works — but it means another appointment, another wait, and for a traveler, possibly another trip.

What happens to the sample matters as much as how it was taken. NCI explains that most tissue is fixed, usually in formalin, embedded in a paraffin wax block, and cut into thin slides; those blocks can be saved and analyzed later. The American Cancer Society notes that, depending on the testing method, a sample may need to be sent fresh or in a preservative — so the planned tests should be known before the procedure.

NCI notes that a pathology report typically reaches the doctor within 10 days, and that additional test results may arrive in separate reports. Good coordination means the team taking the sample, the pathologist, and the physicians who will plan treatment agree in advance on the question and the tests.

For many cancers, the diagnosis is no longer only “what type.” NCI notes that pathology increasingly includes molecular analysis to refine the diagnosis and inform treatment. That raises the bar for the sample. NCI lists “not enough tumor tissue in your biopsy sample” among the reasons biomarker testing may not help a patient. The National Lung Cancer Roundtable guide adds that when a sample provides a diagnosis but not enough tissue for biomarker testing, repeating the biopsy is generally advisable — weighed against the risk of delaying treatment, the likely benefit of testing, patient preference, and the risk of the biopsy itself. NCI notes that a blood-based “liquid biopsy” may be an option when a tissue biopsy cannot be done safely.

The practical point: ask before the biopsy whether molecular or genomic testing is likely, and make sure the plan accounts for it.

Most needle biopsies are outpatient, but they still need planning. RadiologyInfo.org advises telling your physicians about all medications — including aspirin, blood thinners, and herbal supplements — and allergies; you may be asked not to eat or drink for eight hours beforehand, and if you receive sedation, someone needs to take you home. Do not stop a prescribed medication on your own; that decision belongs to your physicians.

Plan around results, too: who receives the pathology report, who explains it, and how later test results reach you and your physicians at home. The Centers for Disease Control and Prevention (CDC) recommends seeing your own health care provider or a travel medicine clinician at least four to six weeks before a medical trip and bringing copies of your records, including test results.

One Stop Cabo Health is a medical concierge, not a hospital. Licensed physicians make every clinical decision, and a biopsy happens only if they find it indicated. Our role is ownership of the sequence: one dedicated concierge who coordinates image and record review, specialist evaluation, the biopsy appointment, the handoff to pathology, delivery of results, and the records that travel home with you.

Care is coordinated at top-level private hospital facilities in Los Cabos — on one itinerary, with one point of contact.