Thyroid Scans vs. Biopsy: Which Test Is Best for Spotting Cancer?
"A new study explores how combining thyroid scans can improve accuracy in detecting malignant thyroid nodules, potentially reducing the need for unnecessary biopsies."
The journey of diagnosing thyroid nodules can be filled with uncertainty. While most thyroid nodules are benign, the possibility of malignancy always looms, leading to anxiety and the need for accurate diagnostic tools. Traditionally, fine needle aspiration cytology (FNAC) has been a cornerstone in evaluating these nodules, but its limitations in certain cases have prompted the search for more reliable, non-invasive methods.
Thyroid scintigraphy, or thyroid scanning, has been used to assess thyroid nodules, but questions remain regarding its role. Although critical for determination of autonomously functioning thyroid tissue, conventional scanning has limitations in distinguishing between benign and malignant nodules. Researchers have explored various radiopharmaceuticals to improve the accuracy of thyroid imaging.
This article delves into a study comparing conventional thyroid scintigraphy with newer techniques using 99mTc tetrofosmin (Myoview) and 99mTc (V) DMSA, combined with FNAC, to evaluate solitary thyroid nodules. We'll explore how these methods can improve the accuracy of diagnosis and potentially reduce the need for invasive procedures.
Standard Evaluation and Its Limits
Thyroid nodule evaluation commonly includes ultrasonography and fine-needle aspiration (FNA) or fine-needle aspiration biopsy (FNAB). UpToDate describes thyroid biopsy as an important component of nodule evaluation and the most accurate method for evaluating nodules and selecting patients for surgery. However, a recent review notes that FNAB, despite its high diagnostic accuracy and central role, has important limitations in routine practice. Ultrasound measurement is also subject to limitations, particularly when nodules are measured repeatedly over time.
Myoview and DMSA: A Combined Approach to Thyroid Nodule Evaluation
The study involved 103 patients, predominantly women, with solitary thyroid nodules. All patients underwent a comprehensive evaluation, including a detailed medical history, physical examination, thyroid function tests, and various thyroid scans, including conventional 99mTc pertechnetate scans, 99mTc tetrofosmin (Myoview) scans, and 99mTc (V) DMSA scans. Cytologic assessments were also performed on thyroid nodules that appeared "cold" on conventional scans.
- Conventional 99mTc pertechnetate scans: These scans had limited value in distinguishing between benign and malignant nodules.
- Early-phase Myoview scans: High uptake in the early phase was observed in both malignant and benign nodules, indicating it's not specific for malignancy.
- Combined Myoview and DMSA scans: Researchers found that combining Myoview and DMSA scans provided valuable diagnostic information. Absence of tracer accumulation in both scans strongly suggested a benign nodule.
- Quantitative Analysis: High retention index of Myoview in malignant lesions compared to benign lesions suggested malignancy. A cut-off point >14% could separate between benign and malignant lesions.
Current Evidence on Scans and Biopsy
A 2015 clinicoradiopathologic study by Saban, Zahrani, and Sakhri examined the role of thyroid scintigraphy versus fine-needle aspiration cytology in evaluating solitary thyroid nodules. The American Thyroid Association explains that physical examination and blood tests alone usually cannot determine whether a nodule is cancerous. It states that evaluation often includes specialized tests such as thyroid ultrasonography and fine-needle biopsy. These sources support using imaging and tissue sampling as complementary parts of thyroid nodule assessment rather than relying on examination or blood tests alone.
Why Testing Is Not Perfect
The Lancet describes ultrasound as the principal method for initial nodule assessment and says that fine-needle aspiration provides further cytological determination of benign or malignant disease. It reports that FNA is generally applied to nodules larger than 1–2 cm, based on holistic risk assessment. Other reviews note that many nodules are detected incidentally during imaging for non-thyroid problems or through thyroid nodule screening, complicating evaluation. A separate diagnostic appraisal framework cautions that assessing test accuracy does not necessarily show whether performing the test improves long-term health outcomes through a therapeutic strategy.
Imaging Guides Biopsy
The American College of Radiology's Thyroid Imaging Reporting and Data System (TI-RADS) classifies nodules using specific patterns composed of two or more ultrasound features. According to the TI-RADS guidelines described in the cited study, a nodule suspicious on ultrasound should undergo fine-needle aspiration cytology, with the result guiding further management. Comparative research has examined the accuracy of ultrasonographic features against ultrasound-guided fine-needle aspiration cytology for diagnosing malignant thyroid nodules. Imaging therefore functions primarily as a risk-stratification and biopsy-selection tool, while cytology provides additional diagnostic information.
Improving Thyroid Nodule Assessment: The Future of Diagnosis
The study suggests that Myoview uptake in cold nodules is more indicative of the aggressiveness or grade of a malignant tumor rather than simply distinguishing between benign and malignant lesions. To differentiate between these two, both Myoview and DMSA scans, combined with a regression equation, are needed.
Toward AI-Assisted Imaging
Recent work describes a broader movement toward artificial-intelligence frameworks that function as clinically aligned components of the thyroid imaging ecosystem. The field is also moving toward more accurate diagnosis and fewer unnecessary thyroidectomies, according to a 2025 review of thyroid nodules. Endocrine Practice identifies thyroid ultrasound as the best initial method for evaluating the gland for nodules. Together, these sources point to continued refinement of ultrasound-based risk stratification alongside emerging AI-supported imaging systems.
AI and Clinical Practice
A 2025 study developed an AI classifier integrating an AI-assisted ultrasound diagnosis system, FNAC, and demographic data to improve differentiation between benign and malignant thyroid nodules, with particular attention to indeterminate thyroid nodules. A clinical trial examined how the AI-based S-Detect for Thyroid system influenced ultrasound diagnostic work-ups performed by different ultrasound users. Technical reviews identify low image resolution, speckle noise, and variability as challenges for traditional image-processing methods. These findings suggest that AI may support clinicians and users with different levels of ultrasound experience, but its practical value depends on how it performs within real clinical workflows.
This research highlights the potential of combining different imaging techniques to improve diagnostic accuracy. The use of Myoview and DMSA scans can offer a less invasive route to identifying potential thyroid cancers, and refining the selection process for FNAC, ensuring that biopsies are performed when they are most likely to provide valuable information.
Future studies should explore the findings and refine the diagnostic algorithms to improve the detection of thyroid malignancies while minimizing unnecessary invasive procedures, ultimately leading to better patient outcomes and reduced anxiety for individuals with thyroid nodules.