# Opportunistic osteoporosis screening on FDG PET/CT scans in breast carcinoma: a comparison with DXA

## TL;DR

Breast cancer patients undergoing PET/CT scans can be screened for osteoporosis and fracture risk using CT attenuation values, reducing the need for additional DXA scans.

## Contribution

This study demonstrates that FDG PET/CT scans can effectively detect osteopenia, osteoporosis, and fracture risk with high sensitivity and specificity.

## Key findings

- Post-chemo ± hormonal therapy increases osteopenia, osteoporosis, and fracture risk in breast cancer patients.
- CT attenuation values ≤174.6 HU and ≤117.2 HU detect osteopenia and osteoporosis with high sensitivity and specificity.
- PET/CT scans can identify patients needing osteoporosis treatment without requiring additional DXA referrals.

## Abstract

Reduced bone mineral density is often observed in breast cancer patients. Routine PET/CT scans can be used for detection of low bone mineral density. To evaluate prevalence of osteopenia, osteoporosis and fracture risk in pre and post-therapy breast carcinoma patients undergoing 18F-FDG PET/CT scans.

In this retrospective study L1-L4 vertebral and femoral neck CT mean Hounsfield unit attenuation and their corresponding SUVmax values from initial staging and end of treatment FDG PET/CT scans performed in breast carcinoma patients were compared. Post chemo ± hormonal therapy FDG PET/CT HU values were also compared to DXA scan T- scores.

Significant increase in prevalence of post chemo ± hormonal therapy osteopenia, osteoporosis and fractures (62%, 18% and 16% vs baseline of 35%, 4% and 9% respectively). CECT mean attenuation values of ≤174.6 HU and ≤117.2 HU for detection of osteopenia and osteoporosis with sensitivity of 100% and specificity of 94.2 % for L1-L4 vertebrae, and ≤176.8 HU and ≤117.8 HU for osteopenia and osteoporosis with sensitivity of 100% and specificity 96.4% at femoral necks respectively were suggested. Furthermore, mean attenuation values of ≤125.9 HU with sensitivity and specificity of ~100% and 79% and ≤124.8 HU with sensitivity of 100% and specificity ~79.8% were suggested for increased L1-L4 vertebral and femoral neck fractures prevalence/ risk respectively. An associated post chemo ± hormonal therapy decline in vertebral and femoral neck mean SUVmax values in range of 14% was also observed.

Baseline and post chemo ± hormonal therapy follow up FDG PET/CT scans allow opportunistic evaluation and can identify a significant number of patients with osteopenia, osteoporosis and patients at increased fracture risk with a high sensitivity and good specificity. They have potential to reduce need for DXA referrals, and also enable early initiation of prophylasix and therapy.