Dataset Information

Differentiating Cerebral Toxoplasmosis and Tumor Recurrence by Thallium-201 Single-Photon Emission Computerized Tomography in a 28-Year-Old Female with Astrocytoma.

ABSTRACT: Cerebral toxoplasmosis is an opportunistic infection that, by itself, is difficult to differentiate from cerebral neoplasms by conventional neuroimaging. It rarely occurs concurrently in patients with a primary brain tumor but when it does, it makes diagnosis and management more difficult. This is a case of a 28-year-old female, diagnosed with a right frontal pleomorphic xanthoastrocytoma with several recurrences, treated with surgery, radiation, and chemotherapy. Three years from diagnosis, the patient was readmitted for generalized body weakness, fever, and a decrease in sensorium. A repeat cranial magnetic resonance imaging showed multiple enhancing lesions in both cerebral hemispheres and in the posterior fossa. Serum toxoplasma IgM and IgG antibody titers were elevated. Single-photon emission computerized tomography (SPECT) with thallium-201 did not show increased tracer uptake in these lesions, favoring toxoplasmosis over tumor recurrence. The patient was treated with trimethoprim-sulfamethoxazole with significant improvement. This is a rare account of cerebral toxoplasmosis arising in the setting of astrocytoma. This is also the first case report to demonstrate the value of thallium-201 SPECT in differentiating central nervous system infection from tumor recurrence, which is pivotal in management. More studies exploring the use of thallium-201 SPECT in distinguishing central nervous system infections from glioma and other malignant tumors should be undertaken to maximize this imaging modality in neuro-oncology practice.

SUBMITTER: Dela Vega MP

PROVIDER: S-EPMC10293939 | biostudies-literature | 2023 Jan-Dec

REPOSITORIES: biostudies-literature

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Differentiating Cerebral Toxoplasmosis and Tumor Recurrence by Thallium-201 Single-Photon Emission Computerized Tomography in a 28-Year-Old Female with Astrocytoma.

Dela Vega Mia Patrice MP Opinaldo Paul Vincent PV Batara Julette Marie JM

Case reports in oncology 20230101 1

Cerebral toxoplasmosis is an opportunistic infection that, by itself, is difficult to differentiate from cerebral neoplasms by conventional neuroimaging. It rarely occurs concurrently in patients with a primary brain tumor but when it does, it makes diagnosis and management more difficult. This is a case of a 28-year-old female, diagnosed with a right frontal pleomorphic xanthoastrocytoma with several recurrences, treated with surgery, radiation, and chemotherapy. Three years from diagnosis, the ...[more]

PMID: 37384212

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Project description:BackgroundAuger electron-emitting radionuclides have potential in targeted treatment of small tumors. Thallium-201 (201Tl), a gamma-emitting radionuclide used in myocardial perfusion scintigraphy, decays by electron capture, releasing around 37 Auger and Coster-Kronig electrons per decay. However, its therapeutic and toxic effects in cancer cells remain largely unexplored. Here, we assess 201Tl in vitro kinetics, radiotoxicity and potential for targeted molecular radionuclide therapy, and aim to test the hypothesis that 201Tl is radiotoxic only when internalized.MethodsBreast cancer MDA-MB-231 and prostate cancer DU145 cells were incubated with 200-8000 kBq/mL [201Tl]TlCl. Potassium concentration varied between 0 and 25 mM to modulate cellular uptake of 201Tl. Cell uptake and efflux rates of 201Tl were measured by gamma counting. Clonogenic assays were used to assess cell survival after 90 min incubation with 201Tl. Nuclear DNA damage was measured with γH2AX fluorescence imaging. Controls included untreated cells and cells treated with decayed [201Tl]TlCl.Results201Tl uptake in both cell lines reached equilibrium within 90 min and washed out exponentially (t1/2 15 min) after the radioactive medium was exchanged for fresh medium. Cellular uptake of 201Tl in DU145 cells ranged between 1.6 (25 mM potassium) and 25.9% (0 mM potassium). Colony formation by both cell lines decreased significantly as 201Tl activity in cells increased, whereas 201Tl excluded from cells by use of high potassium buffer caused no significant toxicity. Non-radioactive TlCl at comparable concentrations caused no toxicity. An estimated average 201Tl intracellular activity of 0.29 Bq/cell (DU145 cells) and 0.18 Bq/cell (MDA-MB-231 cells) during 90 min exposure time caused 90% reduction in clonogenicity. 201Tl at these levels caused on average 3.5-4.6 times more DNA damage per nucleus than control treatments.Conclusions201Tl reduces clonogenic survival and increases nuclear DNA damage only when internalized. These findings justify further development and evaluation of 201Tl therapeutic radiopharmaceuticals.

Project description:PurposeCurrent methods for patient-specific voxel-level dosimetry in radionuclide therapy suffer from a trade-off between accuracy and computational efficiency. Monte Carlo (MC) radiation transport algorithms are considered the gold standard for voxel-level dosimetry but can be computationally expensive, whereas faster dose voxel kernel (DVK) convolution can be suboptimal in the presence of tissue heterogeneities. Furthermore, the accuracies of both these methods are limited by the spatial resolution of the reconstructed emission image. To overcome these limitations, this paper considers a single deep convolutional neural network (CNN) with residual learning (named DblurDoseNet) that learns to produce dose-rate maps while compensating for the limited resolution of SPECT images.MethodsWe trained our CNN using MC-generated dose-rate maps that directly corresponded to the true activity maps in virtual patient phantoms. Residual learning was applied such that our CNN learned only the difference between the true dose-rate map and DVK dose-rate map with density scaling. Our CNN consists of a 3D depth feature extractor followed by a 2D U-Net, where the input was 11 slices (3.3 cm) of a given Lu-177 SPECT/CT image and density map, and the output was the dose-rate map corresponding to the center slice. The CNN was trained with nine virtual patient phantoms and tested on five different phantoms plus 42 SPECT/CT scans of patients who underwent Lu-177 DOTATATE therapy.ResultsWhen testing on virtual patient phantoms, the lesion/organ mean dose-rate error and the normalized root mean square error (NRMSE) relative to the ground truth of the CNN method was consistently lower than DVK and MC, when applied to SPECT images. Compared to DVK/MC, the average improvement for the CNN in mean dose-rate error was 55%/53% and 66%/56%; and in NRMSE was 18%/17% and 10%/11% for lesion and kidney regions, respectively. Line profiles and dose-volume histograms demonstrated compensation for SPECT resolution effects in the CNN-generated dose-rate maps. The ensemble noise standard deviation, determined from multiple Poisson realizations, was improved by 21%/27% compared to DVK/MC. In patients, potential improvements from CNN dose-rate maps compared to DVK/MC were illustrated qualitatively, due to the absence of ground truth. The trained residual CNN took about 30 s on a single GPU (Tesla V100) to generate a 512 × $\; \times \;$ 512 × $\; \times \;$ 130 dose-rate map for a patient.ConclusionThe proposed residual CNN, trained using phantoms generated from patient images, has potential for real-time patient-specific dosimetry in clinical treatment planning due to its demonstrated improvement in accuracy, resolution, noise, and speed over the DVK/MC approaches.

Dataset Information

Differentiating Cerebral Toxoplasmosis and Tumor Recurrence by Thallium-201 Single-Photon Emission Computerized Tomography in a 28-Year-Old Female with Astrocytoma.

Publications

Differentiating Cerebral Toxoplasmosis and Tumor Recurrence by Thallium-201 Single-Photon Emission Computerized Tomography in a 28-Year-Old Female with Astrocytoma.

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