Intrauterine adhesions assessment by photoacoustic imaging versus high frequency ultrasound imaging in rats.

OBJECTIVE

To compare the sensitivity of photoacoustic imaging (PAI) in the detection of Intrauterine adhesions (IUA) at different grades with that of high frequency ultrasound (US), and to investigate whether PAI can evaluate IUA noninvasively and quantitatively by monitoring endometrial oxygenation.

MATERIALS AND

METHODS

In vivo high-frequency US/PAI dual-modality imaging was performed in12 rats with IUA and 5 control rats, the monolayer endometrial thickness on US (US-EMT) and the average oxygenation saturation of endometrium on PAI (PA-sO2 Avr) were measured respectively. HE, Masson and immunofluorescence staining were further conducted to investigate the monolayer endometrial thickness (HE-EMT), the number of endometrial glands (HE-EMG), the area ratio of endometrial fibrosis (FAr) and the mean fluorescence intensity of Vascular endothelial growth factor (VEGF) in endometrium (VEGF-MFI). The correlation was analyzed between US-EMT, PA-sO2 Avr and HE-EMT, HE-EMG, FAr, VEGF-MFI. The diagnostic performance of US and PAI for different grades of IUA was compared.

RESULTS

Both US-EMT and PA-sO2 Avr were positively correlated with HE-EMT, HE-EMG, and VEGF-MFI, but negatively correlated with FAr (r = 0.745, 0.608, 0.875, -0.820 and 0.911, 0.756, 0.942, -0.903, respectively). Importantly, the area under the curve (AUC) for detecting stage F1 by PAI was significantly higher than that by US (0.983 vs. 0.625, P = 0.031). No significant difference in the AUC for detecting stage F2 and F3 between PAI and US (0.990 vs 0.987, P = .756; 1.0 vs 1.0, P > .99).

CONCLUSION

PAI can noninvasively and quantitatively evaluate IUA by monitoring endometrial oxygenation, it shows a higher diagnostic performance than US in detecting IUA, especially mild IUA.