Diagnostic Value of Spectral CT-Derived Extracellular Volume Fraction in the Early Detection of Sigmoid Colon...

The occurrence of colorectal metastasis from bladder cancer is an uncommon phenomenon, and the early identification of metastatic foci poses a certain challenge.

A 77-year-old male patient who had been diagnosed with bladder carcinoma underwent radical cystectomy with an ileal conduit. Postoperative spectral contrast-enhanced CT revealed no definitive intra-abdominal metastatic lesions. Following a period of 1 month, the patient presented with abdominal pain and melena, and subsequent spectral contrast-enhanced CT revealed a metastatic lesion in the sigmoid colon and multiple hepatic metastases. A retrospective analysis of the initial postoperative extracellular volume fraction (ECV) images from spectral CT clearly delineated the metastatic lesion in the sigmoid colon, despite the absence of abnormalities on conventional images.

This case report suggests that multiparametric spectral CT, particularly ECV imaging, may detect subtle tissue changes before apparent morphological changes, indicating its potential value in the recognition of early metastatic lesions. To our knowledge, this is the first reported case demonstrating the potential value of spectral CT-derived ECV imaging for the early detection of sigmoid colon metastasis from bladder cancer.