Magnetic resonance imaging frequently changes classification of acute traumatic thoracolumbar spine injuries

Objective: To evaluate the influence of additional (MRI) compared with computed tomography (CT) alone for the classification of traumatic spinal injuries using the Arbeitsgemeinshaft für Osteosynthesefragen (AO) system and the Thoraco-Lumbar Injury Classification and Severity (TLICS) scale. Materials and methods: Images from 100 consecutive patients with at least one fracture on CT were evaluated retrospectively by three radiologists with regard to the AO and TLICS classification systems in 2 steps. First, all images from the initial CT examination were analyzed. Second, 6weeks later, CT and MR images were analyzed together. Descriptive statistics and Wilcoxon tests were performed to identify changes in the number of fractures and ligamentous lesions detected and their corresponding classification. Results: CT and MRI together revealed a total of 196 fractures (CT alone 162 fractures). The AO classification changed in 31%, the TLICS classification changed in 33% of the patients compared with CT alone. Based on CT and MRI together, the TLICS value changed from values < 5 (indication for conservative therapy) to values ≥ 5 (indication for surgical therapy) in 24%. Conclusion: MRI of patients with thoracolumbar spinal trauma considerably improved the detection of fractures and soft tissue injuries compared with CT alone and significantly changed the overall trauma classificatio

Prolonged Antibiotic Prophylaxis in Patients with Bilioenteric Anastomosis Undergoing Percutaneous Radiofrequency Ablation

PURPOSE: To reduce risk of development of a hepatic abscess in patients with preexisting bilioenteric anastomosis (BEA) undergoing radiofrequency (RF) ablation of hepatic tumors by use of prolonged antibiotic prophylaxis over at least 10 days. MATERIALS AND METHODS: Between April 2003 and June 2011, 184 patients underwent 206 percutaneous RF ablation procedures for hepatic malignancies. Eight patients presented with BEA and were treated in 10 sessions at 14 tumor locations. These 8 patients were male and ranged in age from 55-73 years. Median follow-up was 34 months. Antibiotic prophylaxis was given before the intervention (n = 9, piperacillin/tazobactam; n = 1, ciprofloxacin). Oral antibiotic prophylaxis after the intervention was continued with ciprofloxacin for at least 10 days. In four cases, prophylaxis after the intervention was extended with additional antibiotics. RESULTS: A liver abscess occurred 22 days after 1 of 10 RF ablation sessions in patients with preexisting BEA. The patient who developed an abscess presented with a large hepatocellular carcinoma (59 mm × 54 mm) and underwent transarterial chemoembolization 8 days before RF ablation. No hepatic abscess occurred after 196 RF ablation sessions in 176 patients without BEA. CONCLUSIONS: Preexisting BEA is a risk factor for formation of hepatic abscesses after RF ablation. An antibiotic prophylaxis regimen before the intervention and for a prolonged period after the intervention that covers anaerobic bacteria for at least 10 days is presented. Combined therapy of transarterial chemoembolization and RF ablation increases the risk for complications in patients with known BEA

Multipolar radiofrequency ablation using internally cooled electrodes in ex vivo bovine liver: correlation between volume of coagulation and amount of applied energy

PURPOSE: To evaluate the relationship between applied energy and volume of coagulation induced by multipolar radiofrequency (RF) ablation. METHODS AND MATERIALS: Multipolar RF ablations (n=80) were performed in ex vivo bovine liver. Three bipolar applicators with two electrodes located on each applicator shaft were placed in a triangular array. The power-output (75-225 W) and the distance between the different applicators (2, 3, 4, 5 cm) were systematically varied. The volume of confluent white coagulation and the amount of applied energy were assessed. Based on our experimental data the relationship between the volume of coagulation and applied energy was assessed by nonlinear regression analysis. The variability explained by the model was determined by the parameter r(2). RESULTS: The volume of coagulation increases with higher amounts of applied energy. The maximum amount of energy was applied at a power-output of 75 W and an applicator distance of 5 cm. The corresponding maximum volume of coagulation was 324 cm(3) and required an application of 453 kJ. The relationship between amount of applied energy (E) and volume (V) of coagulation can be described by the function, V=4.39E(0.7) (r(2)=0.88). By approximation the volume of coagulation can be calculated by the linear function V=0.61E+40.7 (r(2)=0.87). CONCLUSION: Ex vivo the relationship between volume of coagulation and amount of applied energy can be described by mathematical modeling. The amount of applied energy correlates to the volume of coagulation and may be a useful parameter to monitor multipolar RF ablation