Idiopathic Multifocal Choroiditis Inflammation Observable Through Multimodal Imaging

Idiopathic multifocal choroiditis inflammation is detectable via various multimodal imaging characteristics, including an increase in focal choroidal thickness, moderately reflective material in the outer retina with disruption of the ellipsoid zone (EZ), and increased areas of hypoperfusion in the choriocapillaris, according to research published in the American Journal of Ophthalmology. These imaging characteristics can guide clinicians in evaluating disease activity.

Researchers conducted a prospective cohort study to identify characteristics on multimodal imaging that define inflammatory activity and distinguish choroidal neovascularization (CNV) activity from inflammatory activity in idiopathic MFC. 

The multimodal imaging included spectral-domain optical coherence tomography (SD-OCT) and angiography (SD-OCT-A), fundus autofluorescence, fundus photography, infrared imaging, and fluorescein angiography and indocyanine green angiography. The investigators compared these measures during active and inactive disease within the same lesion and between active inflammatory lesions with and without CNV activity.

A total of 110 lesions of 50 patients (mean age, 43.7 years; 94% women and 6% men) all diagnosed with Idiopathic multifocal choroiditis inflammation were included in the study. Patients had a median of 3 (interquartile range, 2-5.5) lesions per affected eye.

When comparing active Idiopathic multifocal choroiditis inflammation with inactive disease in 96 lesions without CNV activity, the researchers found increased mean focal choroidal thickness (205 vs 180 µm; P <.001), presence of moderately reflective material located in the sub-retinal pigment epithelium (RPE) and outer retina (67% vs 6%; P <.001), and disruption of the EZ (89% vs 33%; P <.001). 

When comparing the lesions with CNV activity (n=14) and without (n=96), the researchers found increased presence of material with a mixed reflectivity in the subretinal space (93% vs 11%; P <.001), hypotransmission of light to the choroid (36% vs 4%; P <.05), presence of fluid on SD-OCT (no fluid, 50% vs 92%; P <.001), and leakage on fluorescein angiography (46% vs 4%; P <.01). This suggests idiopathic multifocal choroiditis inflammation can be distinguished from CNV activity.

“In the current study, we measured the area of flow voids manually, making this a time-consuming measurement not suitable for the clinical practice. If this could be automatized using specific algorithms, this would probably improve the accuracy of this measurement and makes it suitable for clinical practice,” explain the researchers.

Limitations of the study included the absence of absolute criteria to determine activity in a lesion, a low number of lesions with CNV activity resulting in limited power to detect imaging characteristics indicating CNV activity, not all imaging modalities available in all cases, and poor image quality of the SD-OCT-A in a considerable proportion of the lesions.