B-scan optical coherence tomography angiography (OCT-A) can accurately detect polyps and even could replace indocyanine green angiography (ICGA) for the diagnosis of polypoidal choroidal vasculopathy, researchers found in a retrospective observational case series published in Retina.

The researchers investigated whether B-scan OCT-A, a noninvasive imaging modality, could detect polyp morphology with accuracy comparable with that of ICGA, which involves invasive dye injections that can cause adverse systemic reactions and is not available in all clinical settings.

They compared ICGA and B-scan OCT-A of the characteristics of 76 polypoidal lesions detected with ICGA in 54 eyes of 52 patients (mean age 71 (standard deviation (SD): 7.2 years)) who had been diagnosed with treatment-naïve polypoidal choroidal vasculopathy at Nagoya University Hospital in Japan.


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Two retina specialists who had not seen the ICGA images evaluated the polypoidal lesions on B-scan OCTA images based on the 3 observed diagnostic characteristics: round- or ring-like flow signals beneath the retinal pigment epithelium (RPE), incomplete round- or ring-like optical coherence tomography (OCT) structures beneath the RPE, and flow signals adjacent to the pigment epithelial detachments (PED) notch. 

They detected 72, or 94.7% of the polypoidal lesions that ICGA detected: 46 that were identified as solitary polyps and 26 as multiple cluster polyps. The number of polypoidal lesions per eye matched each other in 50 of the 54 eyes (Kappa=.82). The interrater and the intrarater reliability both showed the highest agreement (Kapp =.85 for both). The research shows 50 lesions were adjacent to both RPE and Bruch’s membrane without serous/serosanguinous PEDS, while 10 were at the margin of serous/serosanguinous still attached to the Bruch membrane and 12 were attached to the RPE, not the Bruch membrane, with serous/serosanguinous PEDs. All polypoidal lesions were at the margin of the branching vascular network (BVNs), except 1, which was surrounded by BVNs.

The researchers found that 58 of the 72 polypoidal lesions showed tangled vascular structures, including coil-like ones, and 3 of the 58 showed single circular vascular structures. They could not distinguish polypoidal lesions from the tangled vessels of BVNs using only en face OCT-A. Researchers noted BVNs in 47 of the 54 eyes on ICGA and 47 showed abnormal flow signals inside lower elevated PEDS on B-scan OCT-A. BVN detection matched between ICGA and B-scan OCT-A in 46 eyes (Kappa=.34) and en face OCT-A detected BVNs as tangled vascular networks in 39 eyes.

When the researchers excluded the 10 eyes with large serosanguinous PEDs, they found BVNs in 35 eyes using en face OCT-A. The technologies, en face OCT-A and ICGA, matched on BVN detection in 40 eyes (Kappa =.23).

“Our findings showed that B-scan images of swept-source OCT-A could detect polypoidal lesions, with an excellent detection rate similar to that of ICGA, although en face OCT-A had no definitive characteristic that can distinguish polypoidal lesions from the tangled vessels of BVNs,” according to investigators.

The study was limited in that it did not compare the OCT-A findings of PCV with those of other age-related macular degeneration subtypes.

Reference

Fujita AI, Kataoka K, Takeuchi J, et al. Diagnostic characteristics of polypoidal choroidal vasculopathy based on b-scan swept-source optical coherence tomography angiography and its interrater agreement compared with indocyanine green angiography. Retina. 2020;40(12):2296-2303. doi:10.1097/IAE.0000000000002760.