Axis or Harris ring in odontoid fractures, old fashioned but not obsolete.

Clearing the cervical spine after blunt trauma remains a challenge. Even in the computed tomography era many emergency departments worldwide still use classical X-rays in first evaluation. Low odontoid fractures are frequently missed, especially in unconscious patients where an open mouth view is not available. Evaluation of the Harris ring in the lateral view can improve identification rate. We studied the diagnostic values of this sign and the educational effect on trainees. Lateral views of 12 computed tomography confirmed low-axis fractures and 13 controls were randomly presented to 17 residents (traumatology, neurosurgery and emergency medicine) and five experienced radiologists. After the residents were taught the use of the axis ring, they had to review the set. Diagnosis was scored with a degree of certitude from 5 to 1. The specificity and sensitivity for the radiologists was 88% (confidence interval 80-96) and 82% (confidence interval 72-91), respectively. The effect of the education on the scores of the residents was evaluated using the Wilcoxon ranking test with a significant effect for the traumatologists (P=0.0008), emergency physicians (P=0.0005) as well for the neurosurgeons (P=0.0087). The axis ring can be a useful diagnostic tool in identifying low odontoid fractures on cross-table cervical spine X-rays. It is easy to teach and should be included in X-ray-based C-spine clearing protocols.

T2 mapping of human femorotibial cartilage with turbo mixed MR imaging at 1.5 T: feasibility.

The feasibility of a high-spatial-resolution technique for mapping T1 and T2 in articular cartilage in the human knee was evaluated. The technique, turbo mixed magnetic resonance (MR) imaging, is based on a pulse sequence in which inversion-recovery and spin-echo measurements are interleaved. The sequence was first validated in a phantom experiment in which T1 and T2 values obtained with an accepted spectroscopic technique were correlated with those obtained by using a clinical magnetic resonance imager with the turbo mixed technique. T2 maps were obtained with turbo mixed imaging in 25 volunteers (17 men, eight women; mean age, 30.8 years; range, 23-45 years). A high correlation (r = 0.99) was found between T1 and T2 values obtained at spectroscopy and those obtained at turbo mixed imaging. Relative differences in the range of cartilage relaxation times between the two techniques were less than 20%. Turbo mixed imaging in human volunteers showed T2 cartilage relaxation times that corresponded with previously published data. Turbo mixed imaging, thus, is feasible for T2 mapping of cartilage.