Microembolization effects of imipenem/cilastatin in vivo Depicted by Monochromatic Synchrotron X-ray Microangiography.

Purpose: To elucidate the characteristics of imipenem/cilastatin (IPM/CS) as an embolic material in microvessels in vivo.

Materials and methods: Three healthy rabbits were injected subcutaneously in one auricle with picibanil in advance to create an inflammation-induced neovascular model. Microangiography was performed using monochromatic X-rays obtained from a large synchrotron radiation facility (super photon ring-8; SPring-8). All rabbits underwent pre-embolization microangiography under anesthesia. Embolization from the central branch of the auricular artery was then performed using a mixture of IPM/CS (0.2 g) + non-ionic contrast medium (2 ml). Microangiography was performed immediately after and at 10, 20, 30, 40, 50, 60, 70, 80, and 90 minutes after embolization. The diameter of embolized vessels was measured from the images immediately after embolization. Recanalization times were evaluated from the post-embolization to 90 minutes after embolization, and they were compared between normal sites and sites where inflammation was induced.

Results: The mean diameter of the embolized vessels immediately after embolization evaluated at the normal site was 267 ± 58.35 (range: 174-363) μm. Evaluation of post-embolization recanalization showed that vessels in the normal sites recanalized after a mean of 70 (range 50-70) min, whereas vessels at the sites of inflammation did not recanalize in observations up to 90 minutes after embolization.

Conclusions: This study characterized IPM/CS as an in vivo embolic substance and the duration of the embolic effect differed between normal and inflamed sites.

Clinical relevance/application: IPM/CS exhibited an ultra-short embolic effect not seen with existing embolic materials and may have a long embolic effect specific to inflamed vessels rather than normal vesseles. This characteristic could contribute to the indications for embolization being expanded to new diseases, such as embolization for pain relief in chronic joint pain.