Pretreatment computed tomography L1 attenuation values: Easy reaching predicting factor for radiation-related bone
Hana Malikova1, Klaudia Graffneter2, Karin Kremenova1
1Department of Radiology and Nuclear Medicine, Third Faculty of Medicine, Charles University and Faculty Hospital Kralovske Vinohrady, Prague, Czech Republic.
Background:
Radiotherapy (RT) brings a broad spectrum of side effects that could affect patient well-being. Pelvic insufficiency fractures (PIF) are one of them.
Objectives:
The aim of our study was to identify easily detectable risk factors for radiation-related PIF.
Design:
Prospective, single-center study.
Methods:
We included 104 patients aged 52.9 ± 13.8 years following radical RT for advanced cervical cancer. Patients underwent a pretreatment computed tomography (CT) imaging and a minimally 1-year follow-up by CT or magnetic resonance imaging. We evaluated the association between pretreatment CT attenuation values of L1, their deviation from normative values, age, body mass index, total received radiation dose, smoking habits, and radiation-related bone side effects.
Results:
In 28 (26.9%) patients PIF were found and first detected at a mean of 16 ± 7 months after RT. Patients with PIF were significantly older; 62.5 ± 10.2 versus 49.4 ± 12.6 years, p > 0.001; their pretreatment CT L1 attenuation values were significantly lower; 117.5 ± 46.9 HU versus 165.9 ± 44.8 HU, p < 0.001, as well as more negative deviation from normative values. Age and L1 attenuation values were strongly correlated, p < 0.001, precluding separation of their independent effects on PIF occurrence. According to logistic regression modeling, a 50-year-old woman had an estimated 16.3% probability of PIF (95% CI [8.6%; 25.9%]); the associated odds ratio increased by approximately 182% [72%; 357%] per 10-year increase in age. Thus, the estimated probability of PIF increased to 34.1% for a 60-year-old and 58.0% for a 70-year-old woman. The pretreatment CT attenuation values of 100 Hounsfield units (HU) were associated with a 51.1% probability of PIF (95% CI [36.2%; 66.5%]), and the probability decreased at higher attenuation values (odds ratio 0.766 [0.663; 0.865] per 10-HU increment). No other variables showed significant associations.
Conclusion:
Increasing age and lower pretreatment CT L1 attenuation values are strong predictors for radiation-related PIF, reflecting osteoporosis status.
