Bone Abstracts

Background and objectives: Fracture rate in Osteogenesis Imperfecta (OI) is highest between 0 and 19 years, and associated radiation exposure also carries the highest lifetime cancer risk. Here, we investigate the cumulative effective radiation dose (E) and lifetime cancer risk from diagnostic imaging in OI children. We also explore the hypothesis that negative family history of OI will increase injury-related, fracture-negative X-rays due to parental anxiety.

Methods: We reviewed all X-ray imaging (X-ray, CT & DXA scans) conducted from 2003 to 2016 in children with OI (0–19 years) with a minimum observation period of 5 years, at Birmingham Children’s Hospital, UK. E was estimated individually and compared across five age groups (0–2, 2–5, 5–9, 9–14, 14–19 years). Lifetime cancer risk was calculated using cumulative E and organ, sex and age specific risk coefficients.

Results: We present preliminary results from 47 children (51% females, 3200 images) with OI Type I (n=26), III (n=6) and IV (n=15). The median (range) observation period was 12.5 years (5.2–14). The number of X-rays per year for Type I was 3.9 (0.14–11.86), Type IV 4.9 (0.86–14.78) and Type III 19.5 (5.66–32.42). Cumulative E was similar for Type I versus Type IV (P=0.132), but higher in Type III compared to Type I and IV (P<0.05), which was consistent across age groups. The additional lifetime cancer risk is 1 in 21,740 (1,083–625,000) for Type I, 1 in 7,180 (1,181–57,964) for Type IV and 1 in 1,130 (383–13,155) for Type III. The lifetime cancer risk for Type III is higher than Type I (P=0.004) but not different to Type IV (P=0.059). Across OI types, fracture-negative X-rays and cumulative E was not influenced by family history of OI.

Conclusions: When compared to baseline lifetime cancer risk (1 in 2) the additional cancer risk from diagnostic imaging is small but not negligible, broadly falling under the categories of ‘very low’ (1 in 10,000–100,000), ‘low’ (1 in 1,000–10,000) and ‘low-moderate’ (1 in 100–10,000) for Type I, IV and III, respectively. Hence it remains important to exercise caution to minimize radiation exposure. Family history of OI does not impact injury-related presentations where X-rays are fracture-negative.

Disclosure: The authors declared no competing interests.