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Updated: Jun 5, 2026
Non-invasive Imaging of Acute Allograft Rejection after Rat Renal Transplantation Using 18F-FDG PET
Published on: April 28, 2013
Noninvasive detection of graft rejection by in vivo (19) F MRI in the early stage
U Flögel1, S Su, I Kreideweiss
1Cardiovascular Physiology, Heinrich Heine University Düsseldorf, Germany. floegel@uni-duesseldorf.de
Abstract:
Diagnosis of transplant rejection requires tissue biopsy and entails risks. Here, we describe a new (19) F MRI approach for noninvasive visualization of organ rejection via the macrophage host response. For this, we employed biochemically inert emulsified perfluorocarbons (PFCs), known to be preferentially phagocytized by monocytes and macrophages. Isografts from C57BL/6 or allografts from C57B10.A mice were heterotopically transplanted into C57BL/6 recipients. PFCs were applied intravenously followed by (1) H/(19) F MRI at 9.4 T 24 h after injection. (1) H images showed a similar position and anatomy of the graft in the abdomen for both cases. However, corresponding (19) F signals were only observed in allogenic tissue. (1) H/(19) F MRI enabled us to detect the initial immune response not later than 3 days after surgery, when conventional parameters did not reveal any signs of rejection. In allografts, the observed (19) F signal strongly increased with time and correlated with the extent of rejection. In separate experiments, rapamycin was used to demonstrate the ability of (19) F MRI to monitor immunosuppressive therapy. Thus, PFCs can serve as positive contrast agent for the early detection of transplant rejection by (19) F MRI with high spatial resolution and an excellent degree of specificity due to lack of any (19) F background.
Insights
A novel fluorine-19 MRI (19F MRI) technique uses perfluorocarbons (PFCs) to visualize transplant rejection noninvasively. This method detects early immune responses by tracking macrophage activity, offering high specificity and resolution.
Area of Science:
- Biomedical Imaging
- Transplantation Immunology
- Magnetic Resonance Imaging
Background:
- Transplant rejection diagnosis typically relies on invasive tissue biopsies, posing risks to patients.
- Macrophages play a crucial role in the host response to organ transplant rejection.
- Current diagnostic methods may not detect early signs of rejection.
Purpose of the Study:
- To develop and evaluate a noninvasive (19)F MRI approach for early detection of transplant rejection.
- To utilize perfluorocarbons (PFCs) as a contrast agent for visualizing macrophage activity in rejecting allografts.
- To assess the capability of (19)F MRI to monitor the progression of rejection and the efficacy of immunosuppressive therapy.
Main Methods:
- Emulsified perfluorocarbons (PFCs) were administered intravenously to mice undergoing heterotopic transplantation.
- High-field (9.4 T) (1)H/(19)F MRI was performed to image the transplanted organs.
- Comparison of signal intensity between isografts and allografts was conducted.
- The correlation between (19)F signal and the extent of rejection was analyzed.
- The ability to monitor immunosuppressive therapy (rapamycin) was evaluated.
Main Results:
- Noninvasive (19)F MRI successfully visualized macrophage-mediated immune responses in allografts but not in isografts.
- Early signs of rejection were detected as early as 3 days post-surgery, preceding conventional detection methods.
- The observed (19)F signal intensity increased over time in allografts and correlated with the severity of rejection.
- (19)F MRI demonstrated the capacity to monitor the effects of immunosuppressive treatment.
Conclusions:
- Perfluorocarbons (PFCs) serve as effective positive contrast agents for (19)F MRI in detecting transplant rejection.
- (19)F MRI offers a noninvasive, highly specific, and early diagnostic tool for monitoring organ transplant rejection.
- This technique has the potential to improve patient outcomes by enabling timely intervention and personalized therapy management.
