CryptoCEST: A promising tool for spatially resolved identification of fungal brain lesions and their differentiation from brain tumors with MRI

MRI changes in cryptococcal meningoencephalitis exacerbated by antifungal treatment due to post-infectious inflammatory syndrome: A case report

Cryptococcal meningitis is one of the most common fungal meningitis in adults and causes disabling morbidity and mortality worldwide. The occurrence of postinfectious inflammatory response syndrome during cryptococcal meningitis treatment presents a diagnostic challenge. This time course seems paradoxical because patients show worsening symptoms and imaging findings. However, laboratory data improve with antifungal treatments. Herein, we present a case of an older woman diagnosed with cryptococcal meningitis who later developed postinfectious inflammatory response syndrome. Despite the initial antifungal treatment and improvements in cerebrospinal fluid analysis results, the patient's neurological condition deteriorated; imaging findings worsened. Magnetic resonance imaging at the time of postinfectious inflammatory response syndrome showed more prominent meningeal enhancement and brain edema, consistent with postinfectious inflammatory response syndrome, combined with negative repeat cerebrospinal fluid cultures for cryptococcal species. This case highlights the importance of considering postinfectious inflammatory response syndrome when patients with cryptococcal meningitis show clinical worsening during treatment. Prompt corticosteroid therapy significantly improves patient outcomes. Radiologists and clinicians should be aware of postinfectious inflammatory response syndrome to provide appropriate therapeutic options and improve prognosis in patients with cryptococcal meningitis.

Quantitative MRI of a Cerebral Cryptococcoma Mouse Model for In Vivo Distinction between Different Cryptococcal Molecular Types

The controversially discussed taxonomy of the Cryptococcus neoformans/Cryptococcus gattii species complex encompasses at least eight major molecular types. Cerebral cryptococcomas are a common manifestation of cryptococcal neurological disease. In this study, we compared neurotypical symptoms and differential neurovirulence induced by one representative isolate for each of the eight molecular types studied. We compared single focal lesions caused by the different isolates and evaluated the potential relationships between the fungal burden and properties obtained with quantitative magnetic resonance imaging (qMRI) techniques such as diffusion MRI, T2 relaxometry and magnetic resonance spectroscopy (MRS). We observed an inverse correlation between parametric data and lesion density, and we were able to monitor longitudinally biophysical properties of cryptococcomas induced by different molecular types. Because the MRI/MRS techniques are also clinically available, the same approach could be used to assess image-based biophysical properties that correlate with fungal cell density in lesions in patients to determine personalized treatments.

Amide proton transfer weighted contrast has diagnostic capacity in detecting diabetic foot: an MRI-based case-control study

Objective

To evaluate the role of foot muscle amide proton transfer weighted (APTw) contrast and tissue rest perfusion in quantifying diabetic foot (DF) infection and its correlation with blood parameters.

Materials and methods

With approval from an ethical review board, this study included 40 diabetes mellitus (DM) patients with DF and 31 DM patients without DF or other lower extremity arterial disease. All subjects underwent MRI, which included foot sagittal APTw and coronal arterial spin labeling (ASL) imaging. The normalized MTRasym (3.5 ppm) and the ratio of blood flow (rBF) in rest status of the affected side lesions to the non-affected contralateral side were determined. The inter-group differences of these variables were evaluated. Furthermore, the association between normalized MTRasym (3.5 ppm), rBF, and blood parameters [fasting blood glucose (FBG), glycosylated hemoglobin content, C-reactive protein, neutrophil percentage, and white blood cell count] was explored. Using an ROC curve, the diagnostic capacity of normalized MTRasym (3.5 ppm), BF, and blood biochemical markers in differentiating with or without DF in DM was assessed.

Results

In the DF group, MTRasym (3.5 ppm) and BF in lesion and normalized MTRasym (3.5 ppm) were higher than those in the control group (p < 0.05). In addition, correlations were identified between normalized MTRasym (3.5 ppm) and blood parameters, such as C-reactive protein, glycosylated hemoglobin content, FBG, neutrophil ratio, and white blood cell (p < 0.001). Meanwhile, association between BF in lesion and blood parameters, such as C-reactive protein, neutrophil percentage, and FBG (p < 0.01). AUC of normalized MTRasym (3.5 ppm) in identifying with/without DF in patients with DM is 0.986 (95% CI, 0.918-1.00) with the sensitivity of 97.22% and the specificity of 100%.

Conclusion

Normalized MTRasym (3.5 ppm) and the BF in lesion may be treated as a safer and more convenient new indicator to evaluate the tissue infection without using a contrast agent, which may be useful in monitoring and preoperatively assessing DF patients with renal insufficiency.

Preclinical Models for Cryptococcosis of the CNS and Their Characterization Using In Vivo Imaging Techniques

Infections caused by Cryptococcus neoformans and Cryptococcus gattii remain a challenge to our healthcare systems as they are still difficult to treat. In order to improve treatment success, in particular for infections that have disseminated to the central nervous system, a better understanding of the disease is needed, addressing questions like how it evolves from a pulmonary to a brain disease and how novel treatment approaches can be developed and validated. This requires not only clinical research and research on the microorganisms in a laboratory environment but also preclinical models in order to study cryptococci in the host. We provide an overview of available preclinical models, with particular emphasis on models of cryptococcosis in rodents. In order to further improve the characterization of rodent models, in particular the dynamic aspects of disease manifestation, development, and ultimate treatment, preclinical in vivo imaging methods are increasingly used, mainly in research for oncological, neurological, and cardiac diseases. In vivo imaging applications for fungal infections are rather sparse. A second aspect of this review is how research on models of cryptococcosis can benefit from in vivo imaging methods that not only provide information on morphology and tissue structure but also on function, metabolism, and cellular properties in a non-invasive way.

In vivo assessment of differences in fungal cell density in cerebral cryptococcomas of mice infected with Cryptococcus neoformans or Cryptococcus gattii

In cerebral cryptococcomas caused by Cryptococcus neoformans or Cryptococcus gattii, the density of fungal cells within lesions can contribute to the overall brain fungal burden. In cultures, cell density is inversely related to the size of the cryptococcal capsule, a dynamic polysaccharide layer surrounding the cell. Methods to investigate cell density or related capsule size within fungal lesions of a living host are currently unavailable, precluding in vivo studies on longitudinal changes. Here, we assessed whether intravital microscopy and quantitative magnetic resonance imaging techniques (diffusion MRI and MR relaxometry) would enable non-invasive investigation of fungal cell density in cerebral cryptococcomas in mice. We compared lesions caused by type strains C. neoformans H99 and C. gattii R265 and evaluated potential relations between observed imaging properties, fungal cell density, total cell and capsule size. The observed inverse correlation between apparent diffusion coefficient and cell density permitted longitudinal investigation of cell density changes. Using these imaging methods, we were able to study the multicellular organization and cell density within brain cryptococcomas in the intact host environment of living mice. Since the MRI techniques are also clinically available, the same approach could be used to assess fungal cell density in brain lesions of patients.

Brain abscess in immunocompetent patients: recent findings

PURPOSE OF REVIEW

We conducted a systematic review of the literature to update findings on the epidemiology and the management of cerebral abscesses in immunocompetent patients.

RECENT FINDINGS

Observational studies suggest that the overall prognosis has improved over the last decades but mortality rates remain high. Several parameters may contribute to a better prognosis, including the identification of common risk factors for brain abscess, the systematic use of brain MRI at diagnosis, the implementation of appropriate neurosurgical and microbiological techniques for diagnosis, the optimization of the antibacterial treatment based on epidemiology and pharmacokinetic/pharmacodynamic studies, and a long-term follow-up for detection of secondary complications. Outcome research on brain abscess is mainly based on observational studies. Randomized controlled trials have yet to be performed to identify clinically relevant interventions associated with improved patient-centered outcomes.

SUMMARY

Our review highlights the importance of a multidisciplinary approach to optimize brain abscess management both at the acute phase and in the long-term. Randomized controlled studies are urgently needed to identify interventions associated with improved outcomes.