Abstract
Abstract: :
Purpose: The computed tomography (CT) scan is a useful tool for evaluating orbital pathology. Typically, physicians prefer "direct" coronal views over coronal views which have been "reformatted" from the axial images. This is because the former have finer resolution. The purpose of this study is to compare the use of direct and reformatted coronal CT scans in order to determine whether reformatted images are sufficient to confidently diagnose orbital pathology. Methods: IRB approval was obtained. Twenty CT scans of the orbit were collected over a 3 month period. Each study included both direct coronal and axial views. Reformatted coronal views were then constructed by a CT technician employing a standard protocol. A panel consisting of two ophthalmologists, a neuro–ophthalmologist, and a neuro–radiologist independently evaluated each study. Each reader first evaluated the axial and reformatted coronal images. Diagnoses were recorded along with a "degree of certainty" (DOC) score on a 0 to 5 scale. Next, the reformatted coronal images were replaced by the direct coronal images. Changes in diagnosis were noted, and a second DOC was recorded. Results of the individual readers were compared to the interpretation of the neuro–radiologist, which served as the "gold standard" (GS). Results: There were a total of 27 diagnoses made by GS. Six studies were read as "normal". There was no statistically significant difference between the GS, who changed diagnoses 8.0% of the time, compared to an average of 12.9% among the three other observers (O1, O2, O3) (p = 0.87). Compared to GS, the other three observers correctly identified an average of 43% of all diagnoses using the reformatted images and a mean of 46% using the direct coronal views. This difference was not statistically significant (p = 0.66). The mean DOC improved for all observers reading the direct coronal views compared to the reformatted views (GS: +1.10, p=0.0001, O1: +0.70, p=0.0004; O2: +0.40, p=0.0165; O3: +0.5, p=0.0467). Conclusions: For diagnosing orbital pathology, we find no significant difference between direct and reformatted coronal CT scans. However, our evaluators demonstrate a significantly higher degree of certainty in their diagnoses when reading direct coronal scans. Our results suggest that reformatted coronal CT scans may be sufficient for accurate diagnosis of orbital pathology, avoiding the added risk, inconvenience and cost of obtaining direct coronal scans. However, physicians may not feel as confident using reformatted CT scans, which could result in improper treatment.
Keywords: imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • orbit