5467. The Single Maximum Diameter Compared to the Average Measure Impact on Screening Guidelines in Cystic Neoplasms of Pancreas
Authors * Denotes Presenting Author
  1. Sara Babapour *; Beth Israel Deaconess Medical Center; University of California, Los Angeles
  2. Leo Tsai; Beth Israel Deaconess Medical Center; Massachusetts General Hospital
  3. Abraham Bezuidenhout; Beth Israel Deaconess Medical Center
The average dimension has been utilized for pulmonary nodules in lung cancer screenings since 2015 by American College of Radiology guidelines. We examined the method for malignancy risk assessment in cystic lesions of pancreas on 3D MRCP.

Materials and Methods:
A total of 147 consecutive patients with incidentally detected pancreatic cysts on MRCP were retrospectively identified. The largest cyst in each patient was detected. Two fellowship trained abdominal radiologists with 5+ years of pancreaticobiliary MDC, who were blinded to the data, independently obtained 2 perpendicular diameters on thin and thick slab coronal plane considered as short and long diameters. The anteroposterior cyst diameter was obtained on 3D MRCP axial images. Then the actual volume was calculated by a multislice segmentation method with commonly used radiomic application [Osirix]. Single maximum diameter and the average value (average of maximum diameter + perpendicular short axis) was measured and calculated on each coronal MRCP image. These values were then compared to cystic volume by Pearson correlation. Patients were classified based on single maximum diameter on each pancreatic cyst according to the most recent updated pancreatic screening guidelines (ACR 2019).

A total of 147 cysts were included in our study of which 49 were spherical in shape. The mean value of single maximum diameters and the average dimension was 18.75 ± 13.4mm, 15.9 ± 11.2 mm, respectively, whereas the mean value of cystic volumes was 5816.87 ± 17679 mm<sup>3</sup>. The average cystic dimension (R = 0.74) showed a significant better correlation to cyst volume compared to the single maximum diameter (R = 0.66) (p < 0.01) among cysts smaller than 3 cm. Also, 33% (48/147) of patients were reclassified to a lower category of follow-ups with longer in-between scan periods by the average dimension according to Fukuoka 2017 and ACR 2019 guidelines.

The average of two dimensions is a stronger reflection of 3D spatial cyst volume and 2D surface area compared to a maximum diameter in a single dimension. 33% of patients fall into a lower-risk group by the average value of diameters which serves as fewer unnecessary scans and follow ups for better patient care and financial management. Neoplastic cystic lesions less than 3 cm in the longest diameter are managed conservatively every 3 to 12 months based on hospital protocols, according to their guidelines. These follow ups commenced on incidental findings and are sometimes continued lifelong. We compared the correlation between the cystic average coronal dimensions and/or single maximum diameters with true cystic volumes to evaluate the impact of average dimension measurements on pancreas cancer surveillance. As a result of greater reflection of elongated and also spherical cysts with stronger correlation to all cystic volume changes during follow-ups we potentially provide premium financial healthcare resource allocation alongside thoughtful approach for patient follow-up management. These goals can simply be achieved by measuring the average cystic diameter.