Flow signal change in polyps after anti-vascular endothelial growth factor therapy

Abstract

Optical coherence tomography angiography (OCTA) is a novel, non-invasive imaging tool used to detect vascular flow. The absence of a flow signal in OCTA in polyps revealed by indocyanine green angiography (ICGA) in patients with polypoidal choroidal vasculopathy (PCV) may indicate slow or compromised filling of blood flow from choroidal vessels. Naïve patients with PCV treated with intravitreal injections of aflibercept (IVI-A) were enrolled in this study to validate the hypothesis that baseline flow may affect the outcome of polyp regression in ICGA. The flow signal of polyps in OCTA was detected by manual segmentation in the corresponding location by ICGA. Polyps were defined as high-flow if both OCTA and ICGA showed positive findings, and low-flow if OCTA showed a negative flow signal in 3 consecutive horizontal scans at the polyp area shown in ICGA. A total of 24 polyps were identified in 13 PCV patients at baseline. Of these 24 polyps, 22 (91.7%) were high-flow and 2 (8.3%) were low-flow. After 3 monthly IVI-A, all low-flow polyps had complete regression in ICGA. Among 17 (77%) high-flow polyps at baseline that had regression after treatment, 10 (58.8%) became low-flow, while 5 (22.7%) persistent polyps remained high-flow. Flow signal of polyps as detected by OCTA could be a predictive factor for treatment response in patients with PCV. Monitoring changes in flow signal after treatment is clinically relevant.

Fig 1. ICGA and OCTA of high-flow polyp and low-flow polyp.

(A) ICGA revealed one polyp (arrow). (B~D) The polyp (arrow) was identified by en face flow OCTA, and flow signal (arrow) was identified by en face flow OCTA, and flow signal was detectable in all 3 consecutive horizontal scans at the center of the polyp. The polyp was then defined as “high flow.” (E) Two polyps identified on ICGA (arrow and dotted arrow). (F~H) En face OCTA and 3 consecutive horizontal scan of the 2 types of polyps. The flow signal of “high flow” polyp (arrow) was detectable in en face and all 3 consecutive horizontal scans, while the flow signal of the “low flow” polyp (dotted arrow) could not be detected in en face and all 3 horizontal scans.

Fig 2. Outcomes of the 24 polyps detected in ICGA and flow signal changes in OCTA before and after 3 monthly loading of intra-vitreal injections of aflibercept (IVI-A).

Fig 3. ICGA and OCTA of case 1.

(A) ICGA before treatment showed 3 polyps, labeled as polyp 1 (long arrow), polyp 2 (short arrow), and polyp 3 (arrowhead). (B) ICGA after treatment showed complete regression of polyp 1 and 3, but partial regression in the size of polyp 2 (short arrow). (C) OCTA of polyp 1 before and (D) after treatment showed the presence of flow signal (long arrow). (E) OCTA of polyp 2 before and (F) after treatment showed the presence of flow signal (short arrow). (G) OCTA of polyp 3 before and (H) after treatment showed the presence of flow signal (arrowhead).

Fig 4. ICGA and OCTA of case 3.

(A) ICGA before treatment showed 2 polyps, labeled as polyp 5 (arrowhead) and polyp 6 (arrow). (B) ICGA after treatment showed complete regression of polyp 5, but partial regression of polyp 6 (arrow). (C) OCTA of polyp 5 before and (D) after treatment showed the absence of flow signal (arrowhead) in this low-flow polyp. (E) OCTA of polyp 6 before treatment showed the presence of flow signal (arrow) but (F) the absence of flow signal (arrow) after treatment. Note the decrease in subretinal fluid and height of pigment epithelial detachment after treatment.

Fig 5. ICGA and OCTA of case 6.

(A) ICGA before treatment showed 4 polyps, labeled as polyp 9 (long arrow), polyp 10 (short arrow), polyp 11 (dotted arrow) and polyp 12 (arrowhead). (B) ICGA after the treatment showed complete regression of polyp 9 and 12, but the persistence of polyp 10 (short arrow) and polyp 11 (dotted arrow). (C) OCTA of polyp 9 before treatment showed the presence of flow signal (arrow) but (D) the absence of flow signal (arrow) after treatment. Note that the adjacent signal was projection artifacts from the retinal vessels. (E) OCTA of polyp 10 before and (F) after treatment showed the presence of flow signal (short arrow). (G) OCTA of polyp 11 before and (H) after treatment showed the presence of flow signal (dotted arrow). (I) OCTA of polyp 12 before treatment showed the presence of flow signal (arrowhead) but (J) the absence of flow signal (arrowhead) after treatment.