Detection and diagnosis of posterior circulation calcification: An interobserver agreement study.

Background: Posterior cerebral ischemic stroke and its underlying causes can be easily misdiagnosed in routine practice. Therefore, more than a third of positive cases can be easily missed during routine CT image reporting unless expert neuroimaging radiologists carefully report it. Objective: To assess the inter-rater agreement level between senior residents and general radiologists and a specialized expert neuroradiologist when detecting and diagnosing posterior cerebral circulation calcification. Methods: This was a cross-sectional observational study. A total of fifteen senior radiology residents (SRRs) and fifteen general radiologists (GRs) at four different hospitals in Riyadh, Saudi Arabia, were included in the study. A total of four CT-scanned brain cases with the presence of posterior circulation calcification (PCC) with different degrees of severity and one brain case with negative PCC were selected. These cases were predefined by expert neuroradiologists at our center. The cases were uploaded into the picture archiving and communication systems (PACS) at four different centers as outsider cases. These cases were then randomly assigned to the participating SRRs and GRs for reporting. All radiologists were blinded to the findings of the cases. Inter-observer agreement was assessed using the weighted kappa coefficient of agreement (k) between the two groups. Results: The cerebral calcification misdiagnosis rate for the SRRs and GRs was > 93% for most of the positive cases. There was 1) poor inter-observer agreement between the SRRs and GRs for the detection of severe posterior cerebral calcification(PCC) in a negative stroke case (agreement for misdiagnosis, k = 0.93; correct diagnosis, k = 0.00), 2) poor inter-observer agreement for mild PCC in a negative stroke case (agreement for misdiagnosis, k = 0.93; correct diagnosis, k = 0.00), 3) moderate PCC in a positive posterior stroke case (agreement for misdiagnosis, k = 0.92; correct diagnosis, k = 0.00), and 4) poor interobserver agreement for severe PCC in a positive posterior cerebral stroke case (agreement for misdiagnosis, k = 0.846; correct diagnosis, k = 0.00). There was excellent agreement between the SRRs and GRs when reporting negative cases of PCC and stroke. Conclusion: Our study concluded that most of the SRRs and GRs missed the diagnosis of posterior cerebral calcification in the presented cases.