Diffusion-weighted imaging in brain aspergillosis

Tumor or not a tumor: Pitfalls and differential diagnosis in neuro-oncology

The majority of intracranial expansive lesions are tumors. However, a wide range of lesions can mimic neoplastic pathology. Differentiating pseudotumoral lesions from brain tumors is crucial to patient management. This article describes the most common intracranial pseudotumors, with a focus on the imaging features that serve as clues to detect pseudotumors.

Magnetic Resonance Imaging Prognostic Findings for Visual and Mortality Outcomes in Acute Invasive Fungal Rhinosinusitis

PURPOSE

To identify initial, preintervention magnetic resonance imaging (MRI) findings that are predictive of visual and mortality outcomes in acute invasive fungal rhinosinusitis (AIFRS).

DESIGN

Retrospective cohort study.

PARTICIPANTS

Patients with histopathologically or microbiologically confirmed AIFRS cared for at a single, tertiary academic institution between January 2000 and February 2020.

METHODS

A retrospective review of MRI scans and clinical records of patients with confirmed diagnosis of AIFRS was performed. For each radiologic characteristic, a modified Poisson regression with robust standard errors was used to estimate the risk ratio for blindness. A multivariate Cox proportional hazards model was used to study AIFRS-specific risk factors associated with mortality.

MAIN OUTCOME MEASURE

Identification of initial, preintervention MRI findings associated with visual and mortality outcomes.

RESULTS

The study comprised 78 patients (93 orbits, 63 with unilateral disease and 15 with bilateral disease) with AIFRS. The leading causes of immunosuppression were hematologic malignancy (38%) and diabetes mellitus (36%). Mucormycota constituted 56% of infections, and Ascomycota constituted 37%. The overall death rate resulting from infection was 38%. Risk factors for poor visual acuity outcomes on initial MRI included involvement of the orbital apex (relative risk [RR], 2.0; 95% confidence interval [CI], 1.1-3.8; P = 0.026) and cerebral arteries (RR, 1.8; 95% CI, 1.3-2.5; P < 0.001). Increased mortality was associated with involvement of the facial soft tissues (hazard ratio [HR], 4.9; 95% CI, 1.3-18.2; P = 0.017), nasolacrimal drainage apparatus (HR, 5.0; 95% CI, 1.5-16.1; P = 0.008), and intracranial space (HR, 3.5; 95% CI, 1.4-8.6; P = 0.006). Orbital soft tissue involvement was associated with decreased mortality (HR, 0.3; 95% CI, 0.1-0.6; P = 0.001).

CONCLUSIONS

Extrasinonasal involvement in AIFRS typically signals advanced infection with the facial soft tissues most commonly affected. The initial, preintervention MRI is prognostic for a poor visual acuity outcome when orbital apex or cerebral arterial involvement, or both, are present. Facial soft tissues, nasolacrimal drainage apparatus, intracranial involvement, or a combination thereof is associated with increased mortality risk, whereas orbital soft tissue involvement is correlated with a reduced risk of mortality.

Cerebral aspergillosis in the era of new antifungals: The CEREALS national cohort study Nationwide CEREbral Aspergillosis Lesional study (CEREALS)

BACKGROUND

Cerebral aspergillosis (CA) is a life-threatening disease for which diagnosis and management remain challenging. Detailed analyses from large cohorts are lacking.

METHODS

We included 119 cases of proven (n = 54) or probable (n = 65) CA diagnosed between 2006 and 2018 at 20 French hospitals. Data were collected at baseline and during follow-up. Cerebral imaging was reviewed centrally by two neuroradiologists.

RESULTS

The most frequent underlying conditions were hematological malignancy (40%) and solid organ transplantation (29%). Galactomannan was detected in the serum of 64% of patients. In 75% of cases, at least one of galactomannan, Aspergillus PCR, and β-d-glucan was positive in the cerebrospinal fluid. Six-week mortality was 45%. Two distinct patterns of disease were identified according to presumed route of dissemination. Presumed haematogenous dissemination (n = 88) was associated with a higher frequency of impaired consciousness (64%), shorter time to diagnosis, the presence of multiple abscesses (70%), microangiopathy (52%), detection of serum galactomannan (69%) and Aspergillus PCR (68%), and higher six-week mortality (54%). By contrast, contiguous dissemination from the paranasal sinuses (n = 31) was associated with a higher frequency of cranial nerve palsy (65%), evidence of meningitis on cerebral imaging (83%), macrovascular lesions (61%), delayed diagnosis, and lower six-week mortality (30%). In multivariate analysis and in a risk prediction model, haematogenous dissemination, hematological malignancy and the detection of serum galactomannan were associated with higher six-week mortality.

CONCLUSION

Distinguishing between hematogenous and contiguous dissemination patterns appears to be critical in the workup for CA, as they are associated with significant differences in clinical presentation and outcome.

Invasive sinus aspergillosis with mycotic aneurysm of the vertebral artery and subarachnoid hemorrhage - Case report

Invasive sinus aspergillosis is a rare life-threatening condition usually found in immunocompromised patients. The fungus spreads from paranasal sinuses into the central nervous system by direct extension or through blood vessels. Perineural spread is an uncommon mechanism of spread in invasive aspergillosis. A mycotic aneurysm is a dangerous complication of invasive sinus aspergillosis because of its insidious development and is often diagnosed only post-mortem after causing fatal intracranial hemorrhage. Intracranial vascular complications of invasive sinus aspergillosis require prompt recognition and treatment and should always be considered when a diagnosis of CNS aspergillosis is made. We present a case of invasive sinus aspergillosis in an apparently immunocompetent patient that manifested with a brain abscess, perineural spread of the infection, and mycotic aneurysm of the vertebral artery with subsequent rupture and fatal subarachnoid hemorrhage. This case highlights the possibility of perineural spread and hemorrhagic complications in invasive cerebral aspergillosis.

Cerebral mucormycosis: neuroimaging findings and histopathological correlation

INTRODUCTION

Mucormycosis are infections caused by molds of the order Mucorales. These opportunistic infections are rare, difficult to diagnose, and have a poor prognosis. We aimed to describe common radiographic patterns that may help to diagnose cerebral mucormycosis and search for histopathological correlations with imaging data.

METHODS

We studied the radiological findings (CT and MRI) of 18 patients with cerebral mucormycosis and four patients' histopathological findings.

RESULTS

All patients were immunocompromised and/or diabetic. The type of lesions depended on the infection's dissemination pathway. Hematogenous dissemination lesions were most frequently abscesses (59 lesions), cortical, cortical-subcortical, or in the basal ganglia, with a halo aspect on DWI for lesions larger than 1.6 cm. Only seven lesions were enhanced after contrast injection, with different presentations depending on patients' immune status. Ischemia and hemorrhagic areas were also seen. Vascular lesions were represented by stenosis and thrombosis. Direct posterior extension lesions were bi-fronto basal hypodensities on CT and restricted diffusion without enhancement on MRI. A particular extension, perineural spread, was seen along the trigeminal nerve. Histopathological analysis found endovascular lesions with destruction of vessel walls by Mucorales, microbleeds around vessels, as well as acute and chronic inflammation.

CONCLUSIONS

MRI is the critical exam for cerebral mucormycosis. Weak ring enhancement and reduced halo diffusion suggest the diagnosis of fungal infections. Involvement of the frontal lobes should raise suspicion of mucormycosis (along with aspergillosis). The perineural spread can be considered a more specific extension pathway of mucormycosis.

MRI of Emergent Intracranial Infections and Their Complications

Acute intracranial infections of the central nervous system and skull base are uncommon but time sensitive diagnoses that may present to the emergency department. As symptoms are frequently nonspecific or lack typical features of an infectious process, a high index of suspicion is required to confidently make the diagnosis, and imaging may not only serve as the first clue to an intracranial infection, but is often necessary to completely characterize the disease process and exclude any confounding conditions. Although computed tomography is typically the initial imaging modality for many of these patients, magnetic resonance imaging offers greater sensitivity and specificity in diagnosing intracranial infections, characterizing the full extent of infection, and identifying potential complications. The aim of this article is to serve as a review of the typical and most important imaging manifestations of these infections that can be encountered in the emergent setting.

MR Target Sign in Cerebral Aspergillosis

Magnetic resonance (MR) is an effective imaging modality in the evaluation of infectious brain disease, yet findings are often nonspecific. The presence of a diagnostic feature can facilitate early treatment, particularly where mortality is high. We highlight MR apparent diffusion coefficient/T2-weighted target sign in the diagnosis of cerebral aspergillosis.

Invasive sphenoid sinus aspergillosis mimicking sellar tumor: a report of 4 cases and systematic literature review

Background

Invasive sphenoid sinus aspergillosis is a rare but life-threatening condition usually found in immunocompromised patients. When involving cavernous sinus and surrounding structures, patients are frequently misdiagnosed with a neoplasm or sellar abscess. Timely diagnosis and intervention are crucial to patients’ outcomes. The objective of this study is to review cases of invasive sphenoid sinus aspergillosis to describe disease manifestations, imaging features, treatment, and outcome.

Case presentation

We describe four patients with invasive sphenoid sinus aspergillosis misdiagnosed as sellar tumors preoperatively. The mass was completely removed in three patients and partially removed in one patient microscopically. Pathological examinations confirmed Aspergillus in all cases. All four patients received anti-fungal agents postoperatively. There was no recurrence at the time of each patient’s follow-up date. One patient with complete resection was lost to follow-up while the other three patients’ neurologic function improved. Additionally, we performed a systematic review regarding invasive sphenoid sinus aspergillosis of existing English literature.

Conclusion

With regard to clinical symptoms, headache, vision impairment, and ophthalmoplegia were observed in over half of the patients in the literature. A sellar mass with bone destruction on CT and involvement of cavernous sinus is highly suggestive of invasive fungal sphenoid sinusitis. Immediate surgical removal of the lesion is recommended for invasive sphenoid sinus aspergillosis to preserve nerve function and increase the likelihood of survival.

A Diagnostic Dilemma: Similarity of Neuroradiological Findings in Central Nervous System Hemophagocytic Lymphohistiocytosis and Aspergillosis

Central nervous system (CNS) involvement in the context of hemophagocytic lymphohistiocytosis (HLH) is not uncommon. Given the immunosuppressive nature of HLH therapy, infectious complications are also seen. We describe a 9-year-old male who developed acute neurological decline secondary to aspergillosis while undergoing HLH therapy. The significant overlap observed in CNS neuroimaging of HLH and aspergillosis and the subtleties that may help differentiate the two are discussed. The importance of obtaining tissue for definitive diagnosis is underscored.

Magnetic Resonance Imaging of Cerebral Aspergillosis: Imaging and Pathological Correlations

Cerebral aspergillosis is associated with a significant morbidity and mortality rate. The imaging data present different patterns and no full consensus exists on typical imaging characteristics of the cerebral lesions. We reviewed MRI findings in 21 patients with cerebral aspergillosis and correlated them to the immune status of the patients and to neuropathological findings when tissue was available. The lesions were characterized by their number, topography, and MRI signal. Dissemination to the brain resulted from direct spread from paranasal sinuses in 8 patients, 6 of them being immunocompetent. Hematogenous dissemination was observed in 13 patients, all were immunosuppressed. In this later group we identified a total of 329 parenchymal abscesses involving the whole brain with a predilection for the corticomedullary junction. More than half the patients had a corpus callosum lesion. Hemorrhagic lesions accounted for 13% and contrast enhancement was observed in 61% of the lesions. Patients with hematogenous dissemination were younger (p = 0.003), had more intracranial lesions (p = 0.0004) and had a higher 12-week mortality rate (p = 0.046) than patients with direct spread from paranasal sinuses. Analysis of 12 aneurysms allowed us to highlight two distinct situations. In case of direct spread from the paranasal sinuses, aneurysms are saccular and located on the proximal artery portions, while the hematogenous dissemination in immunocompromised patients is more frequently associated with distal and fusiform aneurysms. MRI is the exam of choice for cerebral aspergillosis. Number and type of lesions are different according to the mode of dissemination of the infection.

CNS infections in patients with hematological disorders (including allogeneic stem-cell transplantation)-Guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO)

Diagnosis of CNS infections remains a great challenge in patients with hematological disorders since symptoms might both be masked and be mimicked by other conditions such as metabolic disturbances or consequences from antineoplastic treatment. Thus, awareness of this complication is crucial and any suspicion of a CNS infection should lead to timely and adequate diagnostics and treatment to improve the outcome in this population.

Infections of the central nervous system (CNS) are infrequently diagnosed in immunocompetent patients, but they do occur in a significant proportion of patients with hematological disorders. In particular, patients undergoing allogeneic hematopoietic stem-cell transplantation carry a high risk for CNS infections of up to 15%. Fungi and Toxoplasma gondii are the predominant causative agents. The diagnosis of CNS infections is based on neuroimaging, cerebrospinal fluid examination and biopsy of suspicious lesions in selected patients. However, identification of CNS infections in immunocompromised patients could represent a major challenge since metabolic disturbances, side-effects of antineoplastic or immunosuppressive drugs and CNS involvement of the underlying hematological disorder may mimic symptoms of a CNS infection. The prognosis of CNS infections is generally poor in these patients, albeit the introduction of novel substances (e.g. voriconazole) has improved the outcome in distinct patient subgroups. This guideline has been developed by the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO) with the contribution of a panel of 14 experts certified in internal medicine, hematology/oncology, infectious diseases, intensive care, neurology and neuroradiology. Grades of recommendation and levels of evidence were categorized by using novel criteria, as recently published by the European Society of Clinical Microbiology and Infectious Diseases.

[Cerebral aspergillosis and liver transplantation: about one case]

Cerebral invasive aspergillosis is a rare but serious infection. Mortality is still high despite appropriate treatment. We report the case of a patient with liver transplantation in the context of alcoholic cirrhosis and transplanted back seven years later consequently to an ischemic cholangitis. Following an acquired active viral infection by HCV and treated by antiviral combination therapy the patient presented six months after this second operation a cerebral aspergillosis of tumour-like presentation. It rapidly evolved to an unfavourable outcome with intracranial hypertension state. If the therapeutic management is well established, the diagnosis is difficult. This observation allows us to discuss the various diagnostic criteria of cerebral aspergillosis.

Differentiation of pyogenic and fungal brain abscesses with susceptibility-weighted MR sequences

INTRODUCTION

Conventional magnetic resonance imaging (MRI) techniques are insufficient to determine the causative agent of brain abscesses. We investigated: (1) the value of susceptibility-weighted MR sequences (SWMRS) in the differentiation of fungal and pyogenic brain abscesses; and (2) the effect of different SWMRS (susceptibility-weighted imaging (SWI) versus venous blood oxygen level dependent (VenoBOLD)) for the detection of specific imaging characteristics of pyogenic brain abscesses.

METHODS

We studied six patients with fungal and ten patients with pyogenic brain abscesses. Imaging characteristics on conventional MRI, diffusion-weighted imaging (DWI) and SWMRS were recorded in all abscesses. All lesions were assessed for the presence of a "dual-rim sign" on SWMRS.

RESULTS

Homogenously hyperintense lesions on DWI were present in 60 % of patients with pyogenic abscesses, whereas none of the patients with fungal abscesses showed such lesions. On SWMRS, 90 % of patients with pyogenic abscesses and 60 % of patients with fungal abscesses had only lesions with a low-signal-intensity rim. On SWI, the dual-rim sign was apparent in all pyogenic abscesses. None of the fungal abscesses on SWI (P = 0.005) or any of the pyogenic abscesses on VenoBOLD (P = 0.005) were positive for a dual-rim sign.

CONCLUSIONS

In fungal abscesses, the dual-rim sign is not present but a prominent peripheral rim or central susceptibility effects on SWI will be seen. The appearance of pyogenic abscesses on SWMRS depends on the used sequence, with the dual-rim sign a specific feature of pyogenic brain abscesses on SWI.

The etiology of ring lesions on diffusion-weighted imaging

This study describes a series of cases and reviews the literature on cases of ring lesion on diffusion-weighted imaging to better appreciate the spectrum of disease associated with this neuroimaging finding. We retrospectively reviewed the MR studies of 15 patients with ring pattern lesions on diffusion-weighted imaging from an inpatient Neurology service of a tertiary care center seen over a ten-year period, and reviewed cases in the literature. Thirty-one cases, including 15 new patients, comprise the study group. Immunocompromised patients accounted for 38% of patients with ring lesions on diffusion-weighted imaging with cerebral aspergillosis in five patients, progressive multifocal leukoencephalopathy in three, primary CNS lymphoma in two, cerebral toxoplasmosis in one, and resolving cerebral hematoma in one. In the immunocompetent group demyelinating lesions including multiple sclerosis, acute disseminated encephalomyelitis, Balo's concentric sclerosis and acute necrotizing encephalitis, were seen in 11 patients, vascular etiology in four and neoplastic in three patients, two primary and one metastatic and pyogenic brain abscess in one. Ring lesions on diffusion-weighted imaging are associated with a spectrum of disease not previously considered. Immunocompromised patients accounted for almost one-half while demyelinating conditions in the immunocompetent patients were most common overall.

Central nervous system infections in cancer patients and hematopoietic stem cell transplant recipients

Central nervous system (CNS) infections in cancer patients present a diagnostic and therapeutic challenge for clinicians. While CNS infections are not frequent complications of cancer, its therapies, or hematopoietic stem cell transplantation, the importance of CNS infections lies in their propensity to result in profound morbidity and substantial mortality in this vulnerable patient population. With an expanding population of patients with malignant disease undergoing more potent and aggressive therapies and with the advent of newer immunomodulatory agents, the incidence of CNS infectious complications is likely to rise. This chapter will summarize the clinical and diagnostic evaluation of potential infections of the CNS in these patients and will discuss particular pathogens of interest with regard to this at-risk patient population.

CNS infections in patients with cancer

PURPOSE OF REVIEW

This article provides a practical clinical approach to potential CNS infections in patients with cancer, discusses problematic presentations of posterior reversible encephalopathy syndrome and immune reconstitution inflammatory syndrome, and includes specific testing and treatment recommendations for bacterial meningitis, invasive fungal infections, and opportunistic viral infections.

RECENT FINDINGS

The major deficits predisposing patients with cancer to CNS infection are neutropenia, barrier disruption, B-lymphocyte or immunoglobulin deficiency, and impaired T lymphocyte-mediated immunity. Evolving patterns of drug resistance and prophylactic antimicrobial regimens have altered the timing and range of organisms causing infections. Increasingly intensive immunosuppression has made new groups of patients vulnerable to infections such as progressive multifocal leukoencephalopathy. New MRI sequences offer the potential to diagnose such infections earlier, at a stage when they are more treatable.

SUMMARY

Despite improved prophylactic and therapeutic antibiotic regimens, CNS infections remain an important source of morbidity and mortality among several cancer patient groups, particularly those patients undergoing craniotomy and those with hematologic malignancies receiving either hematopoietic cell transplantation or other intensive chemotherapy regimens.

Diffusion imaging in brain infections

Diffusion-weighted magnetic resonance imaging (DWI) provides image contrasts that are different from conventional magnetic resonance techniques. DWI is particularly sensitive for detecting acute ischemic stroke, but it also has many other clinical applications, including the evaluation of central nervous system (CNS) infections. This article addresses the role of DWI in the differential diagnosis of CNS infections, and discusses the most common DWI findings for each type of infection.

Diagnostic role of target lesion on diffusion-weighted imaging: a case of cerebral aspergillosis and review of the literature

BACKGROUND/PURPOSE

Target lesions on diffusion-weighted imaging are uncommon and their significance not well appreciated. To assess the diagnostic value of this neuroimaging finding, a case of cerebral aspergillosis is presented and the literature reviewed.

METHODS

The diffusion-weighted magnetic resonance imaging features of target lesions in a case of cerebral aspergillosis with neuropathologic correlate is presented and 8 other cases manifesting this neuroimaging finding are reviewed for etiology, patient immune status, lesion number, enhancement, and location.

RESULTS

The etiologies included cerebral aspergillosis, Balo concentric sclerosis, and acute necrotizing encephalopathy. The cerebral aspergillosis cases were immunocompromised with multiple lesions in 4 of 5 patients. The acute necrotizing encephalopathy and Balo concentric sclerosis patients were immunocompetent with bilateral thalamic lesions in the former and multiple random or solitary lesions in the later. Enhancement was seen in 5 patients.

CONCLUSION

Target lesions on diffusion-weighted imaging are compelling for a diagnosis of cerebral aspergillosis in immunocompromised patients and for acute necrotizing encephalopathy in immunocompetent patients when lesions are bilateral thalamic and Balo concentric sclerosis when white matter is involved.

Diffusion MR imaging features of skull base osteomyelitis compared with skull base malignancy

BACKGROUND AND PURPOSE

SBO is a life-threatening infection that may have radiologic features similar to those of the neoplastic processes. The purpose of this study was to evaluate the DWI findings in SBO to facilitate the differential diagnosis.

MATERIALS AND METHODS

The MR imaging findings of 9 patients with SBO were retrospectively evaluated and compared with MR imaging studies from 9 patients with NPC, 9 with lymphoma, and 9 with metastatic disease of the skull base. ADC measurements were performed from the ADC(ST) and the ADC(NST) in all 4 groups.

RESULTS

The mean ADC(ST) values were 1.26 ± 0.19 × 10(-3) mm(2)/s for SBO, 0.74 ± 0.18 × 10(-3) mm(2)/s for NPC, 0.59 ± 0.11 × 10(-3) mm(2)/s for lymphoma, and 0.99 ± 0.34 × 10(-3) mm(2)/s for metastatic disease, respectively. The mean ADC value of SBO was significantly higher than those of NPC and lymphoma (P < .0001). There was no significant difference for the comparison of SBO and metastatic lesions. When an ADC value equal to or higher than 1.08 × 10(-3) mm(2)/s was used to rule out lymphoma and NPC, the accuracy was 96%.

CONCLUSIONS

Although SBO is a relatively rare condition, its differential diagnosis from neoplastic processes of the skull base is essential to start appropriate treatment promptly. ADC values may help to distinguish patients with SBO from those with malignant lesions.

Central nervous system infections in immunocompromised patients: update on diagnostics and therapy

Infections of the central nervous system (CNS) are increasingly reported in patients with malignancies. Heavily immunocompromised patients like those after allogeneic stem cell transplantation (SCT) or previous T cell depleting treatment regimens (e.g. with fludarabine or alemtuzumab) are at highest risk for cerebral infections. The spectrum of causative organisms may vary greatly, depending on the underlying malignancy, its treatment and various other factors. Toxoplasma gondii and fungi are the leading causative organisms in patients after allogeneic SCT, but also viruses such as herpes simplex virus or JC virus may be detected in these patients. Definitive diagnosis of cerebral infection still remains a high challenge, although diagnostics have improved by the wide availability of imaging techniques and polymerase chain reaction in recent years. Novel therapeutic options are arising, particularly for fungal CNS infections. Here, we summarise aspects on epidemiology, clinical symptoms and prognosis of CNS infections in patients with malignancies. Additionally, we give an overview on the diagnostics and management of cerebral infections in these patients including evidence evaluation of efficacy of treatment.