Diagnostic accuracy of limited-volume cone-beam computed tomography in the detection of periapical bone loss: 360° scans versus 180° scans

To investigate the effect of reducing limited-volume cone-beam computed tomographs arc of rotation from 360° to 180° on the ability to diagnose small, artificially created apical lesions.

Small, artificial apical bone lesions were prepared with a bur in the apical region of the distal root of ten mandibular first molars, in human dry mandibles. The jaws were scanned in a fixed position with limited-volume CBCT making a 360° and 180° arc of rotation, before and after each periapical lesion had been created. A 4 × 4 cm field of view was used at 90 kV, with a current of 4 mA. Ten examiners blinded to the scan parameters and controls scored the presence/absence of bone lesions. Intra-examiner reliability was determined after 2 weeks, reviewing half the data set. Statistical analyses with paired t-tests determined the diagnostic accuracy of the two modalities (360° vs. 180°) in terms of sensitivity, specificity, receiver operating characteristic area under the curve, positive predictive values and negative predictive values.

The mean values for sensitivity of the 360° and 180° scans were 0.91 and 0.89, respectively; their mean specificities were 0.73. No significant differences were reflected in the statistical analyses.

Both 360° and 180° cone-beam computed tomography scans yielded similar accuracy in the detection of artificial bone lesions. The use of 180° scans might be advisable to reduce the radiation dose to the patient in line with the ICRP guidance to use as low a dosage as reasonably achievable.