MRTRGMRI Tumor Regression Grade (Rectal)

Radiologic Findings

Assign mrTRG Grade

Scoring Definitions

Grade 1: Complete regression; thin linear fibrosis.
Grade 2: Dense fibrosis; no obvious residual tumor.
Grade 3: Fibrosis > visible tumor.
Grade 4: Visible tumor > fibrosis.
Grade 5: Massive tumor; no response.

Response Status

mrTRG 3

Clinical Strategy

Intermediate response. Mix of fibrosis and visible tumor.

Guidelines & Evidence

Verified

Last Review: 2026

When to Use

Routinely used in the restaging MRI (typically 8-12 weeks post-completion of neoadjuvant radiation or Total Neoadjuvant Therapy) for mid-to-low rectal cancers.

Critical tool in multidisciplinary tumor boards to decide between Total Mesorectal Excision (TME) surgery versus a non-operative "Watch and Wait" protocol.

How it Works

Grading Scale

Grade	Fibrosis vs. Tumor Appearance	Radiologic Outcome
mrTRG 1	Linear scar or no tumor signal (T2 dark). No residual intermediate T2 signal.	Complete radiological response (crCR)
mrTRG 2	Dense fibrosis; no obvious macroscopic tumor, but some heterogeneity.	Good response
mrTRG 3	More than 50% fibrosis, but visible intermediate T2 signal of residual tumor.	Moderate response
mrTRG 4	Little fibrosis, mostly tumor signal.	Poor response
mrTRG 5	No change or overt tumor progression.	No response

Last Comprehensive Review: 2026

MRTRGMRI Tumor Regression Grade (Rectal)

Radiologic Findings

Assign mrTRG Grade

Scoring Definitions

Grade 1: Complete regression; thin linear fibrosis.
Grade 2: Dense fibrosis; no obvious residual tumor.
Grade 3: Fibrosis > visible tumor.
Grade 4: Visible tumor > fibrosis.
Grade 5: Massive tumor; no response.

Response Status

mrTRG 3

Clinical Strategy

Intermediate response. Mix of fibrosis and visible tumor.

Guidelines & Evidence

Verified

Last Review: 2026

When to Use

Routinely used in the restaging MRI (typically 8-12 weeks post-completion of neoadjuvant radiation or Total Neoadjuvant Therapy) for mid-to-low rectal cancers.

Critical tool in multidisciplinary tumor boards to decide between Total Mesorectal Excision (TME) surgery versus a non-operative "Watch and Wait" protocol.

How it Works

Grading Scale

Grade	Fibrosis vs. Tumor Appearance	Radiologic Outcome
mrTRG 1	Linear scar or no tumor signal (T2 dark). No residual intermediate T2 signal.	Complete radiological response (crCR)
mrTRG 2	Dense fibrosis; no obvious macroscopic tumor, but some heterogeneity.	Good response
mrTRG 3	More than 50% fibrosis, but visible intermediate T2 signal of residual tumor.	Moderate response
mrTRG 4	Little fibrosis, mostly tumor signal.	Poor response
mrTRG 5	No change or overt tumor progression.	No response

Last Comprehensive Review: 2026

mrTRG (Rectal MRI)

Radiologic Findings

mrTRG 3

When to Use

When to Use

How it Works

Grading Scale

Clinical Pearls

The "Watch and Wait" Paradigm

Limitations and Pitfalls

The Evidence

Key Reference

Magnetic resonance imaging-detected tumor response for locally advanced rectal cancer predicts survival outcomes: MERCURY experience

Related Tools

Recent Journal Updates

mrTRG (Rectal MRI)

Radiologic Findings

mrTRG 3

When to Use

When to Use

How it Works

Grading Scale

Clinical Pearls

The "Watch and Wait" Paradigm

Limitations and Pitfalls

The Evidence

Key Reference

Magnetic resonance imaging-detected tumor response for locally advanced rectal cancer predicts survival outcomes: MERCURY experience

Related Tools

Recent Journal Updates