title: The "dot-in-circle" sign in musculoskeletal mycetoma on magnetic resonance imaging and ultrasonography.
abstract: This study aimed to present the 'dot-in-circle' sign, which indicates the typical magnetic resonance imaging (MRI) and ultrasonographic (USG) findings for mycetoma involving soft tissue and bone. A total of 8 cases with histopathological proof of mycetoma affecting the musculoskeletal system, and that were examined via MRI and/or coexistent diagnostic ultrasonography between 2004 and 2013 in Songklanagarind Hospital were included in this study. The 'dot-in-circle' sign on the MRI and USG images of all the patients was reviewed by two radiologists. The analytic method was descriptive. All cases of musculoskeletal mycetoma revealed the 'dot-in-circle' sign on MRI, which was seen as multiple, small, round- to oval-shaped hyperintense lesions separated and surrounded by a low-signal intensity rim (circle), and a tiny, central, low-signal focus (dot). An USG study was available in four patients, and all USG findings demonstrated the 'dot-in-circle' sign as a central hyperechoic area (dot) surrounded by hypoechoic tissue (circle). In conclusion, the 'dot-in-circle' sign is a typical feature on MRI and USG findings for the diagnosis of musculoskeletal mycetoma.
authors.affiliation: Division of Diagnostic Radiology, Department of Radiology, Faculty of Medicine, Prince of Songkla University, 15 Karnjanavanit Road, Hat Yai, Songkhla, 90110 Thailand.
authors.forename: Teeranan
authors.initials: T
authors.lastname: Laohawiriyakamol
authors.affiliation: Division of Diagnostic Radiology, Department of Radiology, Faculty of Medicine, Prince of Songkla University, 15 Karnjanavanit Road, Hat Yai, Songkhla, 90110 Thailand.
authors.forename: Pramot
authors.initials: P
authors.lastname: Tanutit
authors.affiliation: Department of Pathology, Faculty of Medicine, Prince of Songkla University, 15 Karnjanavanit Road, Hat Yai, Songkhla, 90110 Thailand.
authors.forename: Kanet
authors.initials: K
authors.lastname: Kanjanapradit
authors.affiliation: Division of Diagnostic Radiology, Department of Radiology, Faculty of Medicine, Prince of Songkla University, 15 Karnjanavanit Road, Hat Yai, Songkhla, 90110 Thailand.
authors.forename: Keerati
authors.initials: K
authors.lastname: Hongsakul
authors.affiliation: Department of Radiology, Iwate Medical University School of Medicine, 19-1 Uchimaru, Morioka, 020-8505 Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Ehara
keywords: Dot-in-circle sign; Magnetic resonance imaging; Mycetoma; Ultrasonography