Abstract
Prior reports have demonstrated the improved ability of delayed fluorine-18 (18F) fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) imaging (dual-time-point imaging) in detecting more patients with liver metastases. To evaluate whether routine triple-time-point FDG PET/CT imaging improves the detection of liver metastasis not visualized on initial imaging. To our knowledge, no triple-time-point imaging has been reported. This retrospective study included total 310 patients with various malignancies who underwent PET/CT scans. Triple-time-point imaging including the liver was obtained. The comparison between negative and positive liver lesions on delayed imaging for patients with initial negative imaging were analyzed. Of the 310 patients, 286 did not exhibit liver lesions on initial imaging, but six of the 286 patients exhibited lesions on delayed imaging. No additional liver lesions were detected on further delayed imaging in the 286 patients. The other 24 patients with liver lesions identified on initial imaging still showed lesions on delayed and further delayed imaging. The analysis showed a significant difference in the percentage of colorectal cancer (66.7%) and liver lesions before the PET scan (50.0%) compared with unchanged results (22.1% and 3.9%, respectively). Routine triple-time-point imaging did not improve the detection of liver metastases; however, it may be recommended in patients with colorectal cancer and liver lesions before the PET scan.
Highlights
The detection of liver metastases is critical for cancer staging and disease management
Taking advantage of previous reports in dual-time-point positron emission tomography/computed tomography (PET/CT) imaging [5,6,7,8,9,10,11,12,13], we presumed that liver metastases may be detected only on delayed images, or even only on further delayed images
The mere 2.1% of patients identified may not indicate the importance of delayed imaging, but when it detects liver metastases, it still plays a crucial role in individual disease management
Summary
The detection of liver metastases is critical for cancer staging and disease management. The underlying rationale of dual-time-point imaging is the continued clearance of normal liver tissue activity or continued FDG accumulation in metastatic liver lesions. This effect often results in an improved image contrast of liver metastases [5,6,14,15]. Taking advantage of previous reports in dual-time-point PET/CT imaging [5,6,7,8,9,10,11,12,13], we presumed that liver metastases may be detected only on delayed images, or even only on further delayed images. The study was designed to assess liver metastases detected only seen on delayed rather than on initial FDG PET/CT imaging to evaluate, whether such an additional examination time and radiation exposure are worthy.
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