Combined Use of Magnetic Resonance Imaging and Fine-Needle Aspiration Cytology for Diagnosis of Soft-Tissue Tumors

Background: Magnetic resonance imaging (MRI) and fine-needle aspiration cytology (FNAC) are useful in the diagnosis of soft-tissue tumors and can be performed on outpatients. These modalities are complementary: MRI examines a large area, while FNAC assesses a highly specific region; MRI displays only signal intensities, while FNAC visualizes actual tumor cells. We investigated the combined use of these methods for differentiating malignant and benign tumors. Methods: 148 patients (153 lesions: 137 benign, 16 malignant) underwent preoperative MRI and FNAC. A diagnosis was judged to be correct if one or both diagnoses were correct, incorrect if at least one diagnosis was incorrect, and indeterminate if both diagnoses were indeterminate or if MRI was indeterminate and the FNAC sample was insufficient. Results: The diagnostic yields for MRI only, FNAC only, and their combination were 81.7%, 84.3%, and 92.2%, respectively, indicating that the diagnostic performance of MRI and FNAC was significantly improved when the methods were combined. Conclusions: As compared with either modality used alone, combined preoperative use of MRI and FNAC improved diagnosis of soft-tissue tumors. (J Nippon Med Sch 2020; 87: 54 ― 59)