A Time-of-Flight Positron Emission Tomography (TOF-PET) tomography insert. The insert includes detection modules and photoelectric converters. Each of the photoelectric converters is connected to an electronic signal processing circuit protected by a housing and comprising an electronic signal processing unit and a computer operable to control the electronic signal processing unit and to reconstruct and store images. Each of the detection modules further includes a liquid marker visible in a magnetic resonance image. The insert also includes a liquid marker device visible in the magnetic resonance image. Adjacent detection modules are detachably connected via coupling elements.
