Abstract
ObjectiveTo evaluate the appropriateness of follow-up with only non-enhanced CT (NECT) in patients with gastrointestinal cancer.Subjects and MethodsThis retrospective study included 323 patients with colorectal and gastric cancer who underwent two consecutive CT examinations (CT1 and CT2), including non-contrast and portal venous phase CT images, with an interval of 1 year. Patients were divided into 2 groups: Group A included patients with no hepatic metastasis on CT1 and with or without newly developed metastasis on CT2 to evaluate the diagnostic performance of NECT for detecting newly developed hepatic metastasis; Group B included patients with known hepatic metastasis both on CT1 and CT2 to evaluate the accuracy of NECT for the assessment of hepatic metastasis based on RECIST criteria (version 1.1). Contrast-enhanced CT (CECT) images were considered as reference standards.ResultsGroup A included 172 patients (M:F = 107:65; mean age, 62.6 years). Among them, 57 patients had 95 metastases (mean size, 2.2 ± 1.3 cm). Per patient and per lesion sensitivity for diagnosing newly developed hepatic metastasis was 56.1–66.7% and 52.6–56.8%, respectively. In terms of small metastases (<1.5 cm), per lesion sensitivity was significantly decreased to 28.1–34.4% (P < 0.05). Metastasis size measurements were significantly smaller on NECT (P < 0.001) compared with reference standards. In Group B, the accuracy of response evaluation based on RECIST criteria was 65.6–72.2%.ConclusionsNECT showed inadequate diagnostic performances in both detecting newly developed hepatic metastasis and evaluating the response of hepatic metastasis based on RECIST criteria.
Highlights
The liver is one of the most common sites of metastasis from extrahepatic neoplasms because of high blood flow from the dual arterial and portal venous systems, and because it has a microscopic structure that is conducive to the lodgment of circulating tumor cells and a microscopic environment that favors the rapid growth of established tumor cells [1]
In terms of small metastases (
Metastasis size measurements were significantly smaller on non-enhanced CT (NECT) (P < 0.001) compared with reference standards
Summary
The liver is one of the most common sites of metastasis from extrahepatic neoplasms because of high blood flow from the dual arterial and portal venous systems, and because it has a microscopic structure that is conducive to the lodgment of circulating tumor cells and a microscopic environment that favors the rapid growth of established tumor cells [1]. Contrast-enhanced computed tomography (CECT) is widely used as the primary imaging modality for the evaluation of hepatic metastasis, and overall sensitivity has been reported as approximately 72–83% with recent multi-detector CT systems [3,4]. Alternative imaging modalities can be used, such as non-contrast magnetic resonance imaging (MRI) and ultrasound (US), and 18F-FDG PET in these patients. Limited accessibility, expense, longer scanning times of MRI and 18F-FDG PET, and lower sensitivity and operator dependency of US limit the general use or entire substitution of non-contrast MRI or US in the diagnosis of hepatic metastasis. Contrast-enhanced US (CEUS) proved to be useful in the evaluation of hepatic metastases without nephrotoxicity [8]. CEUS has not been approved yet for the diagnosis of hepatic metastasis in some countries
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