Reproducibility of 3 mm-Slice-Thick Reconstruction of Paranasal Sinus Computed Tomography Scans

Background: After the failure of medical treatment, the surgery of chronic rhinosinusitis (CRS) is planned according to endoscopic and paranasal sinus computed tomography (CT) findings. Objective: The aim of this prospective study was to evaluate whether this study method might be eligible in studies aiming at radiation dose reduction. Sinus CT scans were chosen as a model because of the high variation of the radiological anatomy of surgically important sinonasal structures. We hypothesized that 3 mm-slice-thick reconstruction CT had poor reproducibility. Methods: 59 CRS patients underwent routine multi-detector sinus CT (CTMD). CT3mm was reconstructed from CTMD data-sets. Lund-Mackay (LM) scores and 43 other structural parameters were analyzed blinded. Agreement was studied between CTMD and CT3mm (intra-observer reproducibility), and between three observers (inter-observer reproducibility) by using Cohen’s kappa. Results: The inter-observer agreement was moderate (kappa 0.4 - 0.6, p < 0.01) in the majority of structures of CT3mm scans. The intra-observer reproducibility of CT3mm scans was very good in most structures, however, it was poor in important structures such as frontal and spheno-ethmoid recess, lamina papyracae, and location of optic nerve or anterior ethmoidal artery. The grade of surgeon’s confidence of CT3mm in comparison to CTMD was lower (kappa 0.2 - 0.4, P < 0.05). Conclusion: This methodology might have some use in studies aiming at radiation dose reduction. As was expected, 3 mm-slice-thick reconstruction CT had poor reproducibility and surgeon’s confidence. More recent methods such as cone beam computed tomography scans have nowadays more relevant dose reduction potential.

Reliability of the measurement of glenoid bone defect in anterior shoulder instability

Background:The size of the glenoid bone defect is an important index in selecting the appropriate treatment for anterior shoulder instability.However,the reliability of glenoid bone defect measurement is controversial.The purpose of the present study was to investigate the reliabilities of measurements of the glenoid bone defect on computed tomography and to explore the predisposing factors leading to inconsistency of these measurements.Methods:The study population comprised 69 consecutive patients who underwent surgery for recurrent anterior shoulder dislocation in Peking University Fourth School of Clinical Medicine from March 2016 to January 2017.The glenoid bone defect was measured by three surgeons on‘self-confirmed’and‘designated’3-D en-face views,and repeated after an interval of 3 months.Measurements included the ratio of the defect area to the best-fit circle area,and the ratio of the defect width to the diameter of the best-fit circle.The inter-and intra-observer reliabilities of the measurements were evaluated using intraclass correlation coefficients(ICCs).The maximum absolute inter-and intra-observer differences and the cumulative percentages of cases with inter-and intraobserver differences greater than these respective levels were calculated.Results:Almost all linear defect values were bigger than the areal defect values.The inter-observer ICCs for the areal defect were 0.557 and 0.513 in the‘self-confirmed’group and 0.549 and 0.431 in the‘designated’group.The inter-observer reliabilities for the linear defect were moderate or fair in the‘self-confirmed’group(ICC=0.446,0.374)and‘designated’group(ICC=0.402,0.327).The ICCs for intra-observer measurements were higher than those for inter-observer measurements.The respective maximum interand intra-observer absolute differences were 13.9%and 13.2%in the‘self-confirmed’group,and 15.8%and 9.8%in the‘designated’group.Conclusions:The areal measurement of the glenoid bone defect is more reliable than the linear measurement.The reliability of the glenoid defect areal measurement is moderate or worse,suggesting that a more accurate and objective measurement method is needed in both en-face view and best-fit circle determination.Subjective factors affecting the glenoid bone loss measurement should be minimized.