# Decoding Osteoradionecrosis of the Jaw: Radiological Progression and a Novel CT-Based Grading System

## TL;DR

This study examines the radiological progression of osteoradionecrosis of the jaw and introduces a new CT-based grading system to aid in early diagnosis and differentiate it from other conditions.

## Contribution

A novel CT-based grading system for osteoradionecrosis of the jaw is proposed to improve early diagnosis and distinguish it from tumor recurrence or infection.

## Key findings

- ORN typically presents with non-healing ulcers, pain, and discharging sinuses, with mandibular involvement being most common.
- CT findings at ORN suspicion include resorption, erosions, sclerosis, and fragmentation, which progress over time.
- The proposed CT-based grading system classifies ORN progression and offers a structured approach for diagnosis.

## Abstract

Osteoradionecrosis of the jaw (ORN) is a serious long-term complication of radiation therapy for head and neck cancers. It often resembles infections or tumor recurrence on imaging, making diagnosis challenging. This study investigates the imaging features and radiological evolution of osteoradionecrosis of the jaw following radiation therapy for head and neck cancers, utilizing mainly CT scans, and describes patterns of ORN on imaging. It also introduces a CT-based grading system aimed at facilitating earlier diagnosis of ORN, distinguishing it from recurrent cancer or osteomyelitis, to guide treatment decisions. Larger prospective studies are needed to validate this grading system and confirm its usefulness in clinical practice.

Background: Osteoradionecrosis (ORN) of the jaw is a severe, progressive complication of radiation therapy for head and neck malignancies. ORN features radiologically overlaps osteomyelitis and tumor recurrence. This study analyzes jaw ORN imaging characteristics and progression and proposes an ORN CT-based grading system that builds on current ClinRAD grades. Materials and Methods: A retrospective cohort study of 35 patients with biopsy-proven or clinically diagnosed ORN following radiation therapy. Initial and follow-up imaging were assessed to evaluate the radiological evolution of ORN. The imaging findings were statistically analyzed using IBM SPSS v26, and literature comparisons were made. Results: The median onset of ORN post-radiotherapy was 27–28 months (range: 2–119 months). The most common clinical presentations included non-healing ulcers (49%), pain (34%), and discharging sinuses (31%). Mandibular involvement was predominant (51%), with focal bone alterations being more frequent (63%). CT findings at clinical suspicion of ORN included resorption (100%), erosions (100%), sclerosis (86%), and fragmentation (83%). Follow-up imaging showed increased bone erosion (77%), fragmentation (92%), and sclerosis (92%). A CT-based grading system is proposed to classify ORN progression. Conclusions: ORN follows a predictable radiological progression, beginning with trabecular resorption and cortical erosion, leading to fragmentation and sequestrum formation. The proposed grading system provides a structured approach for early diagnosis. The proposed grading system provides a structured approach for diagnosis. Larger studies of imaging analyses are required to validate these findings and refine diagnostic criteria.