Abstract
ObjectivesThe aim of this study was to evaluate the value of a delayed positron emission tomography/magnetic resonance (PET/MR) scan relative to a single positron emission tomography/computed tomography (PET/CT) scan for liver metastasis detection.MethodsIn this study, 70 patients with solid malignancies and suspicious liver lesions undergoing 2-deoxy-2-[18F]fluoro-D-glucose [(18F)FDG] PET/CT and subsequent delayed liver PET/MR scans were analyzed. The histopathological analysis and/or imaging follow-up were performed as the standard of reference. Lesion maximum standardized uptake value (SUVmax), diameter, and tumor to nontumor ratio (T/N) were measured. Lesion detection sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for both examinations.Results(1) The standard of reference revealed 208 liver lesions in 70 patients (metastasis in 56 patients with 196 lesions; benign in 14 patients with 12 lesions). Compared with PET/CT, PET/MR had higher accuracy (98.6% vs. 78.6%), sensitivity (98.2% vs. 76.8%), and specificity (100.0% vs. 85.7%) (2). The therapeutic strategies of 29 patients (41.4%) needed reconsideration after the additional PET/MR, including new metastases detected (13/70), new affected lobes identified (14/70), and false-positive corrected (2/70) (3). PET/MR detected significantly more metastases than PET/CT did, especially with small lesions. The SUVmax of the same lesion correlated well between the two acquisitions, while the delayed PET showed a higher T/N ratio.ConclusionsIn liver metastasis detection, the diagnostic value of the delayed PET/MR is validated to be superior to that of PET/CT, which may aid the clinical decision-making.
Highlights
Clinical management of patients with malignant liver lesions requires advanced diagnostic and therapeutic methods
The aim of this study was to evaluate the value of a delayed positron emission tomography/magnetic resonance (PET/MR) scan relative to a single positron emission tomography/computed tomography (PET/CT) scan for liver metastasis detection
The inclusion criteria for the study participation included any of the following conditions: (a) PET/CT detection of liver metastasis in two lobes, the number being no more than three; (b) PET/CT detection of less than five liver metastases, all in one lobe; (c) CT detection of low-density, non-[18F]FDG avid liver nodules; and (d) suspicious metastases detected by previous medical exams but missed in the PET/CT scan
Summary
Clinical management of patients with malignant liver lesions requires advanced diagnostic and therapeutic methods. Positron emission tomography/computed tomography (PET/CT) has been widely used in solid neoplasm detection and staging [3], including liver malignancies [4], demonstrating higher accuracy in the tumor, node, metastasis (TNM) staging than the single modality of CT or PET [5, 6]. The limitations of PET/CT have been exposed as clinical evidence accumulates. The softtissue contrast of CT is not optimal for diagnosis and differentiation of soft-tissue lesions. PET alone is not enough to draw conclusions on tumors with low metabolic activities, such as welldifferentiated hepatocellular carcinoma, neuroendocrine tumors, and mucinous adenocarcinoma [7,8,9]
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