ABSTRACT
OBJECTIVE: The aim of this study was to compare the performance of positron emission tomography (PET)/magnetic resonance (MR) versus stand-alone PET and stand-alone magnetic resonance imaging (MRI) in the detection and characterization of suspected liver metastases. MATERIALS AND METHODS: This multi-institutional retrospective performance study was approved by the institutional review boards and was Health Insurance Portability and Accountability Act compliant, with waiver of informed consent. Seventy-nine patients with confirmed solid extrahepatic malignancies who underwent upper abdominal PET/MR between February 2017 and June 2018 were included. Where focal hepatic lesions were identified, the likelihood of a diagnosis of a liver metastasis was defined on an ordinal scale for MRI, PET, and PET/MRI by 3 readers: 1 nuclear medicine physician and 2 radiologists. The number of lesions per patient, lesion size, and involved hepatic segments were recorded. Proof of metastases was based on histopathologic correlation or clinical/imaging follow-up. Diagnostic performance was assessed using sensitivity, specificity, positive and negative predictive values, and receiver operator characteristic curve analysis. RESULTS: A total of 79 patients (53 years, interquartile range, 50-68; 43 men) were included. PET/MR had a sensitivity of 95%, specificity of 97%, positive predictive value of 97%, and negative predictive value of 95%. The sensitivity, specificity, positive predictive value, and negative predictive value of MRI were 88%, 98%, 98%, and 90% and for PET were 83%, 97%, 97%, and 86%, respectively. The areas under the curve for PET/MRI, MRI, and PET were 95%, 92%, and 92%, respectively. CONCLUSIONS: Contrast-enhanced PET/MR has a higher sensitivity and negative predictive value than either PET or MRI alone in the setting of suspected liver metastases. Fewer lesions were characterized as indeterminate by PET/MR in comparison with PET and MRI. This superior performance could potentially impact treatment and management decisions for patients with suspected liver metastases.
Subject(s)
Liver Neoplasms , Positron-Emission Tomography , Aged , Female , Fluorodeoxyglucose F18 , Humans , Liver Neoplasms/diagnostic imaging , Magnetic Resonance Imaging , Magnetic Resonance Spectroscopy , Male , Middle Aged , Radiopharmaceuticals , Retrospective Studies , Sensitivity and SpecificityABSTRACT
Purpose@#To study the value of 2-deoxy-2-[18F]fluoro-D-glucose([18F]FDG) positron emission tomography/computed tomography(PET/CT) and [18F]FDG positron emission tomography/magnetic resonance imaging (PET/MRI) in assessing immunocompromisedpatients with suspected malignancy or infection. @*Methods@#[18F]FDG-PET/CT and [18F]FDG-PET/MRI examinations of patients who were immunocompromised after receivinglung, heart, pancreas, kidney, liver, or combined kidney-liver transplants were analyzed in this retrospective study. Patientsunderwent whole-body hybrid-imaging because of clinical signs of malignancy and/or infection. Findings were assessed bymolecular features ([18F]FDG-uptake) and morphological changes. The final diagnosis, which was arrived at after review ofclinical, laboratory, and histopathologic analyses and follow-up imaging studies, served as the reference standard. @*Results@#Altogether, (i) 28 contrast-enhanced [18F]FDG-PET/CT scans (CE-PET/CT), (ii) 33 non-contrast [18F]FDG-PET/CTscans (NC-PET/CT), and (iii) 18 [18F]FDG-PET/MRI scans were included. Additionally, 12/62 patients underwent follow-upPET imaging to rule out vital tumor ormetabolic active inflammatory processes. CE-PET/CT exhibited 94.4%sensitivity, 80.0%specificity, 89.5% positive predictive value (PPV), 88.9% negative predictive value (NPV), and 89.3% accuracy with regard tothe reference standard. NC-PET/CT exhibited 91.3% sensitivity, 80.0% specificity, 91.3% PPV, 80.0% NPV, and 87.9% accuracy. PET/MRI exhibited 88.6% sensitivity, 99.2% specificity, 99.6% PPV, 81.3% NPV, and 94.4% accuracy. ExactMcNemar statistical test (one-sided) showed significant difference between the CT-/MR-component alone and the integratedPET/CT and PET/MRI for diagnosis of malignancy or infection (p value < 0.001). Radiation exposure was 4- to 7-fold higherwith PET/CT than with PET/MRI. @*Conclusion@#For immunocompromised patients with clinically unresolved symptoms, to rule out vital tumor manifestations ormetabolic active inflammation, [18F]FDG-PET/MRI, CE-[18F]FDG-PET/CT, and NC-[18F]FDG-PET/CT exhibit excellent performancein diagnosing malignancy or infection. The main strength of PET/MRI is its considerably lower level of radiationexposure than that associated with PET/CT.
