Measurement of torsion angles of long finger bones using computed tomography.

OBJECTIVE: Rotational dislocation at the fracture site is a complication of long finger bone fractures of the metacarpals and phalanges. To evaluate such deformities, we performed CT of the articular surfaces of these bones to demonstrate the torsion angles. DESIGN: We evaluated 10 pairs of cadaver hands. These were placed flat, with the bones of interest perpendicular to the gantry to acquire axial images. The torsion of the long bone axes was defined as the angle between a tangent positioned parallel to the proximal articular surface and a tangent parallel to the distal articular surface of individual bones. RESULTS: The maximum difference between repeated measurements was 4 degrees. Intraobserver differences measured between right and left hands are less than 3 degrees. CONCLUSION: Side differences in torsion angles exceeding 3 degrees are strongly suspicious of a malrotation after fracture. These measurements might help to plan derotational osteotomy and assess the results of therapy.

[Control of percutaneous biopsy with CT fluoroscopy]. / Steuerung von perkutanen Biopsien mittels CT-Fluoroskopie.

PURPOSE: Clinical evaluation of CT fluoroscopy and comparison with conventional CT guidance for monitoring of non-pulmonary percutaneous biopsy procedures. MATERIALS AND METHODS: 20 non-pulmonary CT-guided biopsy procedures were prospectively performed either with CT fluoroscopy or with conventional CT guidance. CT fluoroscopy was performed using 120 kV and 50, 70 or 90 mA at a frame-rate of three or six images per second. Number of punctures and biopsies, procedure times, radiation doses and histologic results were analyzed separately for conventional CT guidance and for CT fluoroscopy. RESULTS: With CT fluoroscopy, yield of biopsies was improved (p = 0.005, t-test) and procedure times were shorter than for conventional CT guidance (11.4 +/- 6.0 vs. 23.6 +/- 13.8 min; p = 0.03, t-test). Analysis of procedure related radiation exposure and histologic outcome showed no significant difference between conventional and fluoroscopic CT-guided procedures (p > 0.05, t-test). CONCLUSIONS: CT fluoroscopy facilitates guidance of percutaneous biopsy procedures. Compared to conventional CT assistance, procedure times are decreased while yield of biopsies is improved.