Abstract
IntroductionThe aim of this study was to clarify the effectiveness of various imaging modalities and characteristic imaging features in the screening of IgG4-related dacryoadenitis and sialadenitis (IgG4-DS), and to show the differences in the imaging features between IgG4-DS and Sjögren’s syndrome (SS).MethodsThirty-nine patients with IgG4-DS, 51 with SS and 36 with normal salivary glands were enrolled. Images of the parotid and submandibular glands obtained using sonography, 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT), computed tomography (CT) and magnetic resonance imaging (MRI) were retrospectively analyzed. Six oral and maxillofacial radiologists randomly reviewed the arranged image sets under blinded conditions. Each observer scored the confidence rating regarding the presence of the characteristic imaging findings using a 5-grade rating system. After scoring various findings, diagnosis was made as normal, IgG4-DS or SS, considering all findings for each case.ResultsOn sonography, multiple hypoechoic areas and hyperechoic lines and/or spots in the parotid glands and obscuration of submandibular gland configuration were detected mainly in patients with SS (median scores 4, 4 and 3, respectively). Reticular and nodal patterns were observed primarily in patients with IgG4-DS (median score 5). FDG-PET/CT revealed a tendency for abnormal 18F-FDG accumulation and swelling of both the parotid and submandibular glands in patients with IgG4-DS, particularly in the submandibular glands. On MRI, SS had a high score regarding the findings of a salt-and-pepper appearance and/or multiple cystic areas in the parotid glands (median score 4.5). Sonography showed the highest values among the four imaging modalities for sensitivity, specificity and accuracy. There were significant differences between sonography and CT (p = 0.0001) and between sonography and FDG-PET/CT (p = 0.0058) concerning accuracy.ConclusionsChanges in the submandibular glands affected by IgG4-DS could be easily detected using sonography (characteristic bilateral nodal/reticular change) and FDG-PET/CT (abnormal 18F-FDG accumulation). Even inexperienced observers could detect these findings. In addition, sonography could also differentiate SS. Consequently, we recommend sonography as a modality for the screening of IgG4-DS, because it is easy to use, involves no radiation exposure and is an effective imaging modality.
Highlights
The aim of this study was to clarify the effectiveness of various imaging modalities and characteristic imaging features in the screening of Immunoglobulin G4 (IgG4)-related dacryoadenitis and sialadenitis (IgG4-DS), and to show the differences in the imaging features between IgG4-related dacryoadenitis and sialadenitis (IgG4-DS) and Sjögren’s syndrome (SS)
No punctate or globular sialectasis have been observed on sialograms in IgG4-DS, while they are generally observed in SS
Average kappa values for each finding were 0.62 for sonography, 0.61 for FDG-PET/computed tomography (CT), 0.51 for CT and 0.54 for magnetic resonance imaging (MRI); no findings showed an inverted order of scores the second time
Summary
The aim of this study was to clarify the effectiveness of various imaging modalities and characteristic imaging features in the screening of IgG4-related dacryoadenitis and sialadenitis (IgG4-DS), and to show the differences in the imaging features between IgG4-DS and Sjögren’s syndrome (SS). Immunoglobulin G4 (IgG4)-related dacryoadenitis and sialadenitis (IgG4-DS), Mikulicz’s disease, has recently been recognized as being an independent entity from Sjögren’s syndrome (SS), because of its clinical and serological features [1,2,3]. No punctate or globular sialectasis have been observed on sialograms in IgG4-DS, while they are generally observed in SS. They considered IgG4-DS to be an entity independent of SS, it is known that there are patients who have active disease but normal serum IgG4 levels [4]
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