Optoacoustic (photoacoustic) imaging dramatically improves upon conventional bio-optic barriers and enables three-dimensional, high-resolution optical imaging deep inside tissues (several mm to cm). Clinical optoacoustic macroscopy has been supported by two ERC Advanced Awards (2008, 2016; Prof. Ntziachristos). In parallel, under the ICT program INNODERM, we developed mesoscopic optoacoustic imaging for dermatology diagnostics. Termed raster-scan optoacoustic mesoscopy (RSOM), the method can image previously invisible ❶ pathophysiological/oxygenation and ❷ morphological features of the skin at depths of 1-5mm. RSOM has already shown clinical diagnostic value in dermatology and, fuelled by INNODERM, has been commercialised and globally placed by iThera Medical. WINTHER builds on this success. While INNODERM focused on diagnostic dermatology, it has become apparent that RSOM can also assess progression and therapy not only in skin but also in cardiovascular diseases and diabetes. However, to achieve this, RSOM should be able to assess endothelial function, ability that it is not yet available. WINTHER will build next-generation fast RSOM (F-RSOM), operating up to two orders of magnitude faster than state-of-the-art RSOM, enabling it to assess not only ❶,❷ above but also ❸ endothelial function. Using the skin as a window for disease assessment and aided by a modern computation framework, based on deterministic and artificial intelligence algorithms, F-RSOM aims to improve the clinical accuracy of RSOM and shift the paradigm in therapeutic monitoring of cardio-metabolic diseases and inflammatory skin conditions, strengthening Europe's leadership in photonics and in personalized medicine. The project is driven iThera Medical with a strong history of commercializing optoacoustics for clinical applications, by leading physicians (TUM, HUNIMED), and by RSOM, RSOM components and data analysis experts (TUM, iThera, Rayfos, Sonaxis).