The growth rates of solitary gallbladder polyps compared to multi‐polyps: A quantitative analysis

Comparison of the Size Measurement of Gallbladder Polyps by Three Different Radiologists in Abdominal Ultrasonography

BACKGROUND

There is little information regarding the size measurement differences in gallbladder (GB) polyps performed by different radiologists on abdominal ultrasonography (US).

AIM

To reveal the differences in GB polyp size measurements performed by different radiologists on abdominal US.

METHODS

From June to September 2022, the maximum diameter of 228 GB polyps was measured twice on abdominal US by one of three radiologists (a third-year radiology resident [reader A], a radiologist with 7 years of experience in abdominal US [reader B], and an abdominal radiologist with 8 years of experience in abdominal US [reader C]). Intra-reader agreements for polyp size measurements were assessed by intraclass correlation coefficient (ICC). A Bland-Altman plot was used to visualize the differences between the first and second size measurements in each reader.

RESULTS

Reader A, reader B, and reader C evaluated 65, 77, and 86 polyps, respectively. The mean size of measured 228 GB polyps was 5.0 ± 1.9 mm. Except for the case where reader A showed moderate intra-reader agreement (0.726) for polyps with size ≤ 5 mm, all readers showed an overall high intra-reader reliability (reader A, ICC = 0.859; reader B, ICC = 0.947, reader C, ICC = 0.948), indicative of good and excellent intra-reader agreements. The 95% limit of agreement of reader A, B, and C was 1.9 mm of the mean in all three readers.

CONCLUSIONS

GB polyp size measurement on abdominal US showed good or excellent intra-reader agreements. However, size changes of approximately less than 1.9 mm should be interpreted carefully because these may be within the measurement error.

Gallbladder polyps growth rate is an independent risk factor for neoplastic polyps

Background

The size of gallbladder (GB) polyps is a representative risk factor for neoplastic polyps. However, whether growth rate during follow‐up is associated with neoplastic polyps remains unclear.

Methods

From 2009 to 2019, a cohort of patients with GB polyps who underwent cholecystectomy was enrolled. We included only patients who underwent at least two abdominal ultrasonography procedures at least 6 months apart prior to cholecystectomy. Performance and optimal cutoff value of polyp growth rate for predicting neoplastic polyps were estimated using receiver operating characteristic (ROC) analysis. In addition to growth rate, several other variables considered suitable for predicting neoplastic polyps were also investigated. A nomogram was created to predict neoplastic polyps.

Results

A total of 239 patients with neoplastic polyps (n = 27, 11.3%) and non‐neoplastic polyps (n = 212, 88.7%) were included. The median follow‐up period was 28.5 months. The area under the ROC curve (AUROC) of polyp growth rate for neoplastic polyps was 0.66 (95% confidence interval, 0.59–0.72). The growth rate cutoff value for prediction of neoplastic polyps was 3 mm/year (sensitivity, 37.0%; specificity, 86.3%). Multivariate analysis identified several factors predicting neoplastic polyps: polyp size ≥10 mm (odds ratio [OR], 3.74, p = 0.041), solitary polyp (OR, 3.92, p = 0.004), and polyp growth rate ≥ 3 mm/year (OR, 2.75, p = 0.031). The AUROC of the nomogram using these three significant factors in multivariate analysis was 0.71.

Conclusion

GB polyps with a growth rate of over 3 mm per year on ultrasonography during follow‐up should be considered a risk factor for neoplastic polyps.