NI-RADS Calculator

ACR's Neck Imaging Reporting and Data System NI-RADS ™ categories are designed for use after definitive/curative treatment for head and neck cancer, and are not to be used during treatment
Please note:
  • This calculator will generate two different NI-RADS scores for neck lymph nodes and the primary site. If the scores don't match, consider the higher one for the final recommendation.

  • This calculator does not include the "X- modifier":

    • If the primary tumor is unknown, then the authors suggest designating “P-unknown primary”; if the primary cannot be assessed (dental artifact, motion, other technical reasons, or outside FOV), then the authors suggest “P-x

    • Head and neck cancer surveillance MR examinations are often tailored to a specific area of concern (e.g. skull base for perineural tumor spread), in which case the entire neck may not be imaged. If the neck cannot be assessed, then the authors suggest "N-x." 

NI-RADS Main
Which imaging modality do you want to use for scoring?

NI-RADS scoring based on CT ± PET:

Are there prior studies available for comparison?

NI-RADS 0 = Incomplete

Recommendation: Assign score in addendum after prior imaging examinations become available

Primary Site

Which of the following are identified? (select all that apply)
How is the FDG* uptake in the soft tissue?
*FDG= fluorine-18-2-fluoro-2-deoxy-D-glucose
How is the border of the mass (or mass like tissue)?
How is enhancement of the deep tissue?
What kind of mucosal abnormality is there?

NI-RADS Primary 1 = No evidence of recurrence

Recommendation: Routine surveillance

NI-RADS Primary 2a = Low suspicion

Recommendation: Direct clinical inspection

NI-RADS Primary 2b = Low suspicion

Recommendation: Short-interval follow-up (3 months)

NI-RADS Primary 2b = Low suspicion

Recommendation: Perform PET or Short-interval follow-up (3 months)

NI-RADS Primary 3 = High suspicion

Recommendation: Image guided or clinical biopsy if clinically indicated

NI-RADS Primary 4 = Definitive primary site recurrence

Recommendation: Clinical management (treatment of disease with or without biopsy)

Neck nodes

How is the FDG* uptake in the neck lymph nodes?
*FDG= fluorine-18-2-fluoro-2-deoxy-D-glucose
Are there any growing lymph nodes?

NI-RADS Neck 1 = No evidence of recurrence

Recommendation: Routine surveillance

NI-RADS Neck 2 = Low suspicion

Recommendation: Short-interval follow-up (3 months)

NI-RADS Neck 2 = Low suspicion

Recommendation: Perform PET or Short-interval follow-up (3 months)

NI-RADS Neck 3 = High suspicion

Recommendation: Image guided or clinical biopsy if clinically indicated

NI-RADS Neck 4 = Definitive nodal recurrence

Recommendation: Clinical management (treatment of disease with or without biopsy)

NI-RADS scoring based on MRI:

Are there prior studies available for comparison?

NI-RADS 0 = Incomplete

Recommendation: Assign score in addendum after prior imaging examinations become available
Is there pathologically proven or definite radiologic and clinical evidence of progression?

NI-RADS 4 = Definitive recurrence

Recommendation: Clinical management (treatment of disease with or without biopsy)

Primary Site

Which of the following changes are identified? (select all that apply)
Potential pitfall: Be familiar with the appearance of flaps, which often have different enhancement and signal characteristics than the original tumor.
Are there any mucosal abnormalities? (select all that apply)
Is there a mass?
How is the FDG* uptake in the soft tissue?
*FDG= fluorine-18-2-fluoro-2-deoxy-D-glucose

Primary Site

Which of the following are identified? (select all that apply)
Potential pitfall: Be familiar with the appearance of flaps, which often have different enhancement and signal characteristics than the original tumor.
On the first post-treatment MRI, skull base foramina and perineural findings are indeterminate (in the absence of features suspicious for residual or progressive tumor described under NI-RADS 2 and 3) and can be presumed to be post- treatment related and assigned NI-RADS 1, until further assessment on the next MRI
Are there any mucosal abnormalities? (select all that apply)
Is there a mass?
How is the FDG* uptake in the soft tissue?
*FDG= fluorine-18-2-fluoro-2-deoxy-D-glucose

NI-RADS Primary 1 = No evidence of recurrence

Recommendation: Routine surveillance

NI-RADS Primary 1f = No evidence of recurrence

Recommendation: Routine surveillance

NI-RADS Primary 2a = Low suspicion

Recommendation: Direct clinical (visual) inspection

NI-RADS Primary 2b = Low suspicion

Recommendation: Short-interval follow-up (3 months) MRI or PET to assess deep submucosal abnormality or questionable nodes.
Note: PET is not as helpful for evaluation of perineural disease at the skull base. As such, for a Primary 2b or 2f related to perineural soft tissue, short interval follow-up MRI would be preferable over PET.

NI-RADS Primary 2f = Low suspicion

Recommendation: Short-interval follow-up (3 months) MRI or PET to assess deep submucosal abnormality or questionable nodes.
Note: PET is not as helpful for evaluation of perineural disease at the skull base. As such, for a Primary 2b or 2f related to perineural soft tissue, short interval follow-up MRI would be preferable over PET.

NI-RADS Primary 3 = High suspicion

Recommendation: Image guided or clinical biopsy if clinically indicated

Neck nodes

How is the FDG* uptake in the neck lymph nodes?
*FDG= fluorine-18-2-fluoro-2-deoxy-D-glucose
If the primary tumor was FDG avid, is any of the following true about this scan?
Are there any new or enlarging* lymph nodes?
*New or enlarging node = Node that newly develops or grows during the course of surveillance (node not present or smaller on pre-treatment scan.
† This is in contradistinction to irregular borders or necrosis in nodes unchanged or decreasing in size following radiation treatment, which are considered expected post-treatment findings in radiated nodes.
How are the residual lymph nodes lymph nodes?
*New or enlarging node = Node that newly develops or grows during the course of surveillance (node not present or smaller on pre-treatment scan.
† This is in contradistinction to irregular borders or necrosis in nodes unchanged or decreasing in size following radiation treatment, which are considered expected post-treatment findings in radiated nodes.

NI-RADS Neck 1 = No evidence of recurrence

Recommendation: Routine surveillance

NI-RADS Neck 2 = Low suspicion

Recommendation: Short interval follow-up MRI or PET to assess deep
submucosal abnormality or questionable nodes.

NI-RADS Neck 3 = High suspicion

Recommendation: Image guided or clinical biopsy if clinically indicated

NI-RADS Neck 4 = Definitive nodal recurrence

Recommendation: Clinical management (treatment of disease with or without biopsy)

References:

Related Calculators:

More about the NI-RADS™ Calculator

The Neck Imaging Reporting and Data System (NI-RADS™) is a structured surveillance framework developed by the American College of Radiology (ACR) to assist in the interpretation of post-treatment imaging in patients with head and neck cancers. Since its introduction in 2017, NI-RADS™ has played an important role in providing uniform terminology, improving interdisciplinary communication, and supporting evidence-based follow-up strategies for patients undergoing routine cancer surveillance.

This system is specifically tailored for use in individuals with previously treated malignancies involving the upper aerodigestive tract and related structures. NI-RADS™ is compatible with a variety of imaging modalities, including contrast-enhanced CT (CECT), MRI, and hybrid PET/CT or PET/MRI scans, offering flexibility across different diagnostic workflows. By categorizing imaging findings based on recurrence suspicion, it offers practical guidance for managing uncertain or potentially recurrent disease in this complex anatomical region.

NI-RADS™ Categories and Their Implications

NI-RADS™ organizes imaging results into five standardized categories, each reflecting a different level of concern for disease recurrence. These categories are linked with corresponding clinical actions, helping providers tailor surveillance or intervention based on risk level:

  • NI-RADS 0: Represents an incomplete assessment due to missing prior imaging, which is necessary for comparison. A definitive category will be assigned once appropriate reference studies become available.
  • NI-RADS 1: Indicates no evidence of disease recurrence. Imaging reveals only expected post-treatment changes, and continued routine surveillance is typically advised.
  • NI-RADS 2: Suggests low-level suspicion of recurrence. This category is subdivided based on the location and character of findings:
    • NI-RADS 2a: Superficial mucosal changes or mild focal uptake on PET imaging. Direct visualization, such as laryngoscopy or endoscopy, is generally recommended.
    • NI-RADS 2b: Deep or submucosal changes with mild to moderate radiotracer uptake. Short-term follow-up imaging or further assessment with a different modality may be appropriate.
  • NI-RADS 3: Indicates high suspicion for recurrence. Imaging reveals new or enlarging masses, often with intense PET tracer uptake. Biopsy or tissue confirmation is usually warranted.
  • NI-RADS 4: Reflects proven disease recurrence, either via pathology or unmistakable radiological and clinical progression. Appropriate treatment decisions should be initiated by the care team.

Applications and Benefits of NI-RADS™

NI-RADS™ offers significant advantages in routine clinical use. By promoting standardized image interpretation and structured reporting, it helps reduce inter-reader variability and enhances consistency across imaging centers. This uniformity is especially important in the multidisciplinary management of patients with head and neck cancers, where precise communication between radiologists, oncologists, surgeons, and primary care providers can influence the timing and nature of subsequent interventions.

The system’s integration of management recommendations within each category allows for more streamlined patient care, supporting appropriate follow-up intervals and minimizing unnecessary imaging or invasive procedures. For institutions involved in data tracking or quality improvement initiatives, NI-RADS™ also facilitates collection of reproducible data for monitoring outcomes and optimizing care pathways.

Importantly, the framework is adaptable to evolving clinical practices and imaging technology. It can be applied consistently across both academic and community settings, helping providers meet surveillance guidelines and coordinate care in accordance with institutional protocols or national best practices.

Use in Multimodal Imaging and Evolving Cancer Care

NI-RADS™ is well-suited for interpreting results from a wide range of modalities, including emerging technologies like PET/MRI. The system can accommodate nuanced findings from different anatomical compartments of the head and neck region, including the primary tumor bed and regional lymph nodes. This flexibility allows radiologists to account for the varied post-treatment anatomy and physiologic changes that may affect interpretation.

By incorporating a risk-stratified structure that guides decision-making, NI-RADS™ helps bridge the gap between diagnostic imaging and clinical action. Its use contributes to thoughtful, individualized follow-up plans that prioritize both thorough surveillance and patient well-being.

To explore more about the NI-RADS™ system, including original ACR documentation, criteria tables, and imaging examples, please visit the American College of Radiology’s official NI-RADS™ page.