Automatic rib cage unfolding with CT cylindrical projection reformat in polytraumatized patients for rib fracture detection and characterization: Feasibility and clinical application.

OBJECTIVES: To assess the use of CT with unfolded cylindrical projection (UCP) for rib fracture detection and characterization. METHODS: The images from 60 polytraumatized patients who underwent whole body CT were evaluated for the presence and characterization of rib fractures (displaced or not, single or multiple). Two readers independently evaluated conventional CT images and UCP images in two readout sessions at least one month apart. All readouts were timed. A gold standard was established by two radiologists with 12 and 22 years of clinical experience based on the combined analysis of conventional and UCP reformats. RESULTS: Using UCP, the mean evaluation time was 27%-54% shorter (P = 0.01 and <0.0001) while maintaining a comparable diagnostic performance (sensitivity and specificity of 68.4-79.1% and 99.5-99.6% for conventional reformats and 70.6-91.0% and 96.8-97.7% for UCP) and a good reproducibility (Kappa of 0.71). The multiple fracture detection ratio of UCP was similar to that of conventional reformats (>80%). There were more false positives and false negatives using UCP and displaced fractures were harder to characterize. CONCLUSION: UCP yielded a diagnostic performance similar to that of conventional reformats for the detection of rib fractures with a good reproducibility and a noticeable reduction in evaluation time.

Contrast-Enhanced 3-T Perfusion MRI With Quantitative Analysis for the Characterization of Musculoskeletal Tumors: Is It Worth the Trouble?

OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of quantitative perfusion parameters in 3-T MRI for benign-malignant differentiation in musculoskeletal tumors. SUBJECTS AND METHODS: Ninety-five patients with histologically proven musculoskeletal tumors were prospectively included in this study. All patients underwent 3-T contrast-enhanced perfusion MRI with T1 mapping. The extended Tofts pharmacokinetic model was used to obtain four semiquantitative and four quantitative perfusion parameters for each tumor. Two radiologists evaluated all images and manually placed the ROIs in consensus. RESULTS: The 95 patients had 57 (59%) benign and 38 (41%) malignant tumors. Thirty-seven (39%) were bone and 58 (61%) were soft-tissue tumors. No significant differences were found in the perfusion parameters of benign and malignant tumors (p = 0.105-0.609). The best performance for benign-malignant differentiation was found for fractional volume of the extravascular extracellular space, which yielded 79% and 38% sensitivity and specificity. When soft-tissue tumors were considered, the transfer constant from plasma to the extravascular extracellular space exhibited a significant difference (p = 0.028) and had 79% and 27% sensitivity and specificity. CONCLUSION: Quantitative perfusion MRI had fair sensitivity and poor specificity for benign-malignant differentiation, which was similar to that obtained with semiquantitative parameters.

Contrast-enhanced 3T MR Perfusion of Musculoskeletal Tumours: T1 Value Heterogeneity Assessment and Evaluation of the Influence of T1 Estimation Methods on Quantitative Parameters.

OBJECTIVE: To evaluate intra-tumour and striated muscle T1 value heterogeneity and the influence of different methods of T1 estimation on the variability of quantitative perfusion parameters. MATERIAL AND METHODS: Eighty-two patients with a histologically confirmed musculoskeletal tumour were prospectively included in this study and, with ethics committee approval, underwent contrast-enhanced MR perfusion and T1 mapping. T1 value variations in viable tumour areas and in normal-appearing striated muscle were assessed. In 20 cases, normal muscle perfusion parameters were calculated using three different methods: signal based and gadolinium concentration based on fixed and variable T1 values. RESULTS: Tumour and normal muscle T1 values were significantly different (p = 0.0008). T1 value heterogeneity was higher in tumours than in normal muscle (variation of 19.8% versus 13%). The T1 estimation method had a considerable influence on the variability of perfusion parameters. Fixed T1 values yielded higher coefficients of variation than variable T1 values (mean 109.6 ± 41.8% and 58.3 ± 14.1% respectively). Area under the curve was the least variable parameter (36%). CONCLUSION: T1 values in musculoskeletal tumours are significantly different and more heterogeneous than normal muscle. Patient-specific T1 estimation is needed for direct inter-patient comparison of perfusion parameters. KEY POINTS: • T1 value variation in musculoskeletal tumours is considerable. • T1 values in muscle and tumours are significantly different. • Patient-specific T1 estimation is needed for comparison of inter-patient perfusion parameters. • Technical variation is higher in permeability than semiquantitative perfusion parameters.

Posterior Radioscaphoid Angle as a Predictor of Wrist Degenerative Joint Disease in Patients With Scapholunate Ligament Tears.

OBJECTIVE: The purpose of this study is to determine whether the posterior radioscaphoid angle, a marker of posterior displacement of the scaphoid, is associated with degenerative joint disease in patients with scapholunate ligament tears. MATERIALS AND METHODS: Images from 150 patients with wrist pain who underwent CT arthrography and radiography were retrospectively evaluated. Patients with and without scapholunate ligament ruptures were divided into two groups according to CT arthrography findings. The presence of degenerative changes (scapholunate advanced collapse [SLAC] wrist) was evaluated and graded on conventional radiographs. Images were evaluated by two readers independently, and an adjudicator analyzed the discordant cases. Posterior radioscaphoid angle values were correlated with CT arthrography and radiographic findings. The association between posterior radioscaphoid angle and degenerative joint disease was evaluated. Scapholunate and radiolunate angles were considered in the analysis. RESULTS: The posterior radioscaphoid angle was measurable in all patients, with substantial interobserver agreement (intraclass correlation coefficient, 0.75). The posterior radioscaphoid angle performed better than did the scapholunate and radiolunate angles in the differentiation of patients with and without SLAC wrist (p < 0.02). Posterior radioscaphoid angles greater than 114° presented an 80.0% sensitivity and 89.7% specificity for the detection of SLAC wrist. CONCLUSION: Posterior radioscaphoid angles were strongly associated with degenerative wrist disease, with potential prognostic implications in patients with wrist trauma and scapholunate ligament ruptures.