Quantitative evaluation of bone marrow characteristics in occult and subtle rib fractures by spectral CT

Purpose The present study aimed to determine whether the water content change in the medullary cavity of occult rib fractures by spectral computed tomography (CT). Methods The material decomposition (MD) images were reconstructed using the water-hydroxyapatite basis material pairs from spectral CT. The water contents of the medullary cavity in subtle or occult rib fractures and the symmetrical sites of the contralateral ribs were measured, and their difference was calculated. The absolute value of the water content difference was compared to patients without trauma. An independent samples t -test was adopted to compare the consistency of the water content in the medullary cavity of the normal ribs. Intergroup and pairwise comparisons were applied to the difference in water content among the subtle/occult fractures and normal ribs, followed by receiver operating characteristic curve calculations. p < 0.05 was considered to have a statistically significant difference. Results A total of 100 subtle fractures, 47 occult fractures, and 96 pairs of normal ribs were included in this study. The water content of the medullary cavity in the subtle and occult fractures was both higher than that in their symmetrical sites with the difference value of 31.06 ± 15.03 mg/cm 3 and 27.83 ± 11.40 mg/cm 3 , respectively. These difference values between the subtle and occult fractures were not statistically significant ( p = 0.497). For the normal ribs, the bilateral water contents were not statistically different ( p > 0.05) with a difference value of 8.05 ± 6.13 mg/cm 3 . The increased water content of fractured ribs was higher than that of normal ribs ( p < 0.001). According to the classification based on whether the ribs were fractured, the area under the curve was 0.94. Conclusions The water content measured on MD images in spectral CT in the medullary cavity increased as a response to subtle/occult rib fractures.