Dual-energy CT for occult pelvic fractures: An audit and roc analysis.

INTRODUCTION: There is an increasing incidence of hip and pelvic fractures with an ageing population. Accurate and timely diagnosis is important in the emergency setting. While magnetic resonance imaging (MRI) is the gold standard, it is a limited resource. Dual energy CT (DECT) is comparable to MRI in detection of bone marrow oedema. Our hospital was the first centre in our country to introduce DECT for occult pelvic fractures. We aimed to describe its utility in occult pelvic fractures since commencement. METHODS: Retrospective study of consecutive pelvic bone CT (conventional or DECT) performed to look for an occult fracture over a 10-month period. Sensitivity and specificity calculated based on clinical and imaging follow-up. ROC study performed where three observers visually interpreted pelvic radiographs, conventional CT and DECT and scored their confidence for an acute fracture from 1 to 5. The null hypothesis was that DECT would not improve observer performance compared with conventional CT. RESULTS: DECT studies were performed on 178 patients of whom 84 (47%) had acute fractures. Sensitivity on audit was 99% and specificity was 100%. ROC analysis showed that, for all observers, the area under curve increased from radiograph to conventional CT to DECT. The difference between conventional CT and DECT was statistically significant for all observers where metal implants were not present. CONCLUSION: DECT improves accuracy compared to conventional CT in the diagnosis of occult pelvic fractures and should be used for this indication when available.

T2 relaxation time measurements in tibiotalar cartilage after barefoot running and its relationship to ankle biomechanics.

The influence of ankle kinematics and plantar pressure from mid-range barefoot running on T2 relaxation times of tibiotalar cartilage is unknown. This study aimed to quantitatively evaluate the T2 relaxation time of tibiotalar cartilage and ankle biomechanics following 5 km barefoot running. Twenty healthy runners (who had no 5 km barefoot running experience) underwent 3.0-Tesla magnetic resonance (MR) scans and assessment of running gait before and after 5 km barefoot running. Participants were divided into two groups consisting of marathon-experienced (n = 10) and novice (n = 10) with equal number of males and females in each group. Three musculoskeletal radiologists measured T2 relaxation times in 18 regions of the ankle cartilage: anterior zone, central zone, and posterior zone, or lateral, middle, and medial sections in the sagittal plane. Three-dimensional ankle kinetics, kinematics, and plantar pressure were all also assessed during barefoot running. In the novice group, the T2 relaxation time in the posterior zone of tibial cartilage (p = 0.001) and lateral section in both tibial (p = 0.02) and talar (p = 0.02) cartilage were significantly increased after barefoot running. Ankle kinematics exhibited significant changes in females. Plantar loading was shifted from the medial to lateral aspect after running. This included a significant reduction in the loading under the toes and the 1st, 2nd and 3rd metatarsals, with a significant increase under the 4th and 5th metatarsals and lateral midfoot. The results suggest that plantar pressure may directly lead to local increases in cartilage T2 signal, which was not associated with changes in ankle kinematics.