Clinical Application of the Prototype J-PET Device
Condition: Neurodegenerative Diseases; Brain Neoplasms; Neuroendocrine Tumors
MeSH terms: Neuroendocrine Tumors; Brain Neoplasms; Neurodegenerative Diseases
Study type: Observational [Patient Registry]

Summary: 
      Positron emission tomography (PET) is a diagnostic imaging technique that uses positron
      emission (e-) to image changes in diagnosed tissues. Detector systems are an important part
      of PET scanners. They can convert gamma photons into fluorescent photons to obtain
      information about energy, time and position, of the gamma photons obtained through the use of
      an appropriate positron-emitting radiopharmaceutical. Conventional PET scanners are expensive
      mostly because they require the use of LSO (lutetium oxyorthosilicate) or LYSO (lutetium
      yttrium oxyorthosilicate) scintillation crystals. Such crystal scintillators are very costly
      and difficult to obtain, which limits accessibility of the PET- scanners. The prototype J-PET
      scanner tested in this trial uses plastic scintillators in which different physical phenomena
      occur compared to crystal scintillators. In addition, the J-PET scanner prototype is equipped
      with unique software enabling three-photon imaging, based on the annihilation resulting from
      the formation of the orto-positronium (o-Ps) in diagnosed tissue. The aim of this study is to
      demonstrate the clinical acceptability of such scanners based on plastic scintillators, which
      can additionally collect and process information on the lifetime of o-Ps derived from
      routinely used radiopharmaceuticals. Additionally, the aim of this study is to demonstrate
      the use of the new diagnostic indicator "positronium biomarker" in a prospective study,
      compared to routine diagnostic scanning.
    

Detailed description: 
      The J-PET scanner is the world's first positron tomograph based on plastic strip
      scintillators to measure the lifetime of the ortho-positronium (o-Ps) atom. This is a modular
      scanner, designed and installed at the Department of Experimental Particle Physics and
      Applications of the Jagiellonian University in Krakow. The J-PET scanner is based on
      technology patented in 2014 and 2016.

      The J-PET scanner, unlike PET scanners commonly used in diagnostics, has three important
      features:

        1. J-PET scintillators are made of plastic instead of expensive-to-produce LSO (lutetium
           oxyorthosilicate) or LYSO (lutetium yttrium oxyorthosilicate) scintillation crystals use
           in regular PET scanners;

        2. J-PET is modular and can be adapted to the patient's size and expanded to a total-body
           PET scanner because;

        3. J-PET can be used to test an additional parameter called the "positronium biomarker"
           which has not been used so far.

      Ad. 1. Conventional PET scanners use LSO or LYSO scintillation crystals, which exploit the
      photoelectric effect and convert gamma photons into fluorescent photons to obtain information
      on the energy, time and position of gamma photons emitted by the positron annihilation (e+)
      process obtained by using an appropriate e+ emitting radiopharmaceutical. In plastic
      scintillators used in J-PET, the Compton effect is used, i.e. the phenomenon of scattering of
      high-energy photons on free or weakly bound electrons of the scintillator.

      Ad. 2. The modular J-PET scanner can also be easily integrated with existing computed
      tomography (CT) systems, allowing for simultaneous conduction of both types of examinations.

      Ad. 3. Positronium imaging is applied in the J-PET scanner. The PET technique uses
      radioisotopes that emit positron radiation (beta+). Traditional PET scanners image the
      distribution of gamma ray photons produced by the annihilation of an electron (e-) and a
      positron (e+). Annihilation may be preceded by the appearance of a positron atom - a
      quasi-stable system composed of an electron (e-) and its antiparticle - positron (e+), which
      occurs in approximately 30-40% of all annihilations occurring in the patient's body.

      The time of such annihilation taking place through the state of the positronium atom depends
      on whether a positronium will be created in which e- and e+ will have parallel spins (triplet
      state ↑↑, this system is called ortho-positronium - o-Ps) or antiparallel spins (state
      singlet ↑ ↓, this system is called para-positronium - p-Ps). The average life time of o-Ps in
      vacuum is more then 1000 times longer (142 nano-seconds [ns]), then the average life time of
      p-Ps (125 pico-seconds [ps]). The average lifetime of o-Ps in a vacuum is over 1000 times
      longer (142 nanoseconds [ns]) than the average lifetime of p-Ps (125 picoseconds [ps]). The
      second difference is that o-Ps annihilation takes place over 3 photons, which has not been
      detected so far and which traditional PET. the annihilation time of the o-Ps atom can be an
      additional diagnostic parameter ("positronium biomarker") to be measured and analyzed in the
      J-PET scanner.

      The clinical application of such "positronium biomarker" in terms of lesion detection, image
      quality and quantification is yet to be determined, which this study aims to address.
    

Intervention name(s): Positron-Emission Tomography Imaging
Intervention type(s): Diagnostic Test
Intervention description(s): Examination of radiation distribution in the patient brain and body after completing a routine examination on a PET diagnostic device. J-PET prototype tests will be carried out in patients who have undergone a classic PET examination after administration of [18F]FDG), [68Ga]Ga-PSMA or [68Ga]Ga-DOTATATE). The duration of the additional exam will be approximately 20 minutes.
Other intervention name(s): PET Imaging; PET Scan; Positron-Emission Tomography
Observational model: Case-Only
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        The research group in this study consisted of patients who were diagnosed at the Department
        of Nuclear Medicine of the Medical University of Warsaw. Patients underwent routine
        diagnostic positron emission tomography (PET) examination to diagnose diseases of the
        central nervous system (CNS).

        Patient characteristics:

        Patients were over 18 years of age. They were of Polish origin, white.

        The patients represented a variety of CNS disorders, including:

        Brain tumors, such as glial tumors, solid tumors and primary tumors of the nervous system,
        Neurodegenerative diseases, Neuroendocrine tumors.
      
Keywords: PSMA; PET; FDG; DOTATATE; positronium; Somatostatin analogues