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Objective:
Liver metastases (MET) in patients with genitourinary (GU) and gynecologic (GYN) primary cancers are uncommon, ranging from 4.2% to 22.8% (3.4, 24), and their imaging characteristics are not well described. Missed liver MET might be due to lack of recognition rather than failed detection. Therefore, we aim to investigate CT imaging features of liver MET using natural language processing (NL) to gather accurate data from radiology report to select patients with new liver MET from GU and GYN cancers.

Materials and Methods:
Our IRB-approved retrospective study used NL of structured reports to identify patients with GU and GYN cancers who developed new liver MET on portal venous phase CT (=diagnostic) compared to prior CT (=prediagnostic) between 2016-2022. MET were confirmed either on pathology or imaging follow-up. Imaging characteristics including vascularity, heterogeneity, rim-enhancement, necrosis, margin, total number, largest MET size, and presence of steatosis were reviewed. Presence and size of MET in retrospect on prediagnostic CT was recorded. Proportions and 95% confidence intervals (CI) of imaging characteristics were calculated and Chi-square test was applied to investigate proportion difference.

Results:
A total of 398 prediagnostic and diagnostic CTs were analyzed for 199 patients (prostate 25, renal 40, ureter-bladder 43, ovary 35, endometrium 27, cervix 20, uterus 9). For all cancers combined, most liver MET were hypovascular (178/199, 0.89, 95% CI[0.85-0.93]), except for renal cancer of which 1/3 were hypervascular (13/40, 0.32, 95% CI[0.18-0.47]). Less than half of MET had rim-enhancement (84/119, 0.42, 95% CI[0.35-0.49)). Approximately 1/3 and 1/5 of MET appeared as solitary (70/199, 0.35, 95% CI[0.28-0.41]) and subcentimeter lesion (42/199, 0.21, 95% CI[0.15-0.26]). Liver MET from prostate and ovarian cancers were more ill-defined compared to other GU and GYN cancers respectively (p<0.05). Other imaging characteristic were variable among cancers (p>0.05). About 1/5 of MET were present on prediagnostic CT (42/199, 0.21, 95% CI[0.15-0.26]), with a higher proportion in patients with steatotic liver after excluding renal cancer (p<0.05). Mean size (standard deviation) of lesions on prediagnostic CT were 0.7 cm (0.4 cm).

Conclusion:
While most liver MET from GU and GYN cancers are hypovascular lesions, some specific imaging features are distinct among different primary cancers. The presence of steatosis may lower the sensitivity of detecting hypovascular MET. Understanding the imaging features of liver MET and recognizing the presence of hepatic steatosis may improve the detection of liver MET.