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Updated: Oct 17, 2026
3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii
Published on: December 9, 2014
MRI of intracranial toxoplasmosis after bone marrow transplantation
U Dietrich1, M Maschke, A Dörfler
1Department of Neuroradiology, University Hospital, Hufelandstrasse 55, 45122 Essen, Germany. uwe.dietrich@uni-essen.de
Abstract:
Toxoplasma encephalitis was confirmed by biopsy in three patients with bone marrow (BMT) or peripheral blood stem-cell transplantation (PBSCT). All had MRI before antimicrobial therapy. The intensity of contrast enhancement was very variable. One patient had one large, moderately enhancing cerebral lesion and several smaller almost nonenhancing lesions. The second had small nodular and haemorrhagic lesions without any enhancement. The third had late cerebral toxoplasmosis and showed multiple lesions with marked contrast enhancement. The moderate or absent contrast enhancement in the two patients in the early phase of cerebral toxoplasmosis may be related to a poor immunological response, with a low white blood cell count in at least one patient. Both received higher doses of prednisone than the patient with late infection, leading to a reduced inflammatory response. In patients with a low leukocyte count and/or high doses of immunosuppressive therapy, typical contrast enhancement may be absent.
Insights
Toxoplasma encephalitis in transplant patients shows variable MRI contrast enhancement. Reduced enhancement may indicate a poor immune response due to immunosuppressive therapy or low white blood cell counts.
Area of Science:
- Neuroimaging
- Infectious Diseases
- Hematology
Background:
- Toxoplasma encephalitis is a serious opportunistic infection in immunocompromised individuals, particularly after bone marrow (BMT) or peripheral blood stem-cell transplantation (PBSCT).
- Accurate diagnosis and monitoring of treatment response are crucial for patient outcomes.
Observation:
- Three patients undergoing BMT or PBSCT with confirmed Toxoplasma encephalitis underwent MRI prior to antimicrobial therapy.
- MRI revealed variable contrast enhancement patterns of cerebral lesions.
Findings:
- One patient exhibited a large, moderately enhancing lesion with smaller nonenhancing lesions.
- Another patient presented with small, nodular, and hemorrhagic lesions showing no contrast enhancement.
- The third patient, with late-stage disease, displayed multiple lesions with significant contrast enhancement.
Implications:
- Variable or absent contrast enhancement on MRI in early-phase Toxoplasma encephalitis may be associated with a diminished host immune response.
- Factors such as low white blood cell counts and high-dose immunosuppressive therapy (e.g., prednisone) can attenuate the inflammatory response, leading to atypical imaging findings.
- These findings highlight the importance of considering Toxoplasma encephalitis even with non-classic MRI appearances in at-risk transplant populations.
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