Imaging Findings in Intracranial Aspergillus Infection in Immunocompetent Patients

Abstract

To study the neuroimaging features of craniocerebral aspergillosis infection in immunocompetent patients. The clinical and imaging data of 12 patients of aspergillus fungal infection were retrospectively reviewed. Diagnosis of fungal infection was confirmed by histopathologic examination of surgically excised specimen, stereotactic biopsy material, or endoscopic sinus biopsy. The radiologic studies were evaluated for anatomic distribution of lesions, signal intensity, contrast enhancement, presence of hemorrhage, diffusion restriction, perfusion, and spectroscopy characteristics. Medical records, biopsy reports, and autopsy findings were also reviewed. Twelve cases of aspergillosis infections in immunocompetent patients were diagnosed at our hospital over a period of 10 years. Lesions could be classified based on imaging of lesions of sinonasal origin, intracranial mass lesion including both parenchymal or extraparenchymal meningeal based and stroke. Coexisting meningitis was also noted in one patient. Disease of sinonasal origin commonly showed invasion of the cavernous sinus and orbital apex resulting in visual symptoms and multiple cranial nerve palsies. Intracranial mass lesions without sinonasal involvement were seen in five cases that included isolated parenchymal lesion in two patients and dural-based mass lesions in three patients. Isolated intraparenchymal lesions included two cases of fungal cerebritis. Dural-based lesions were large granulomas with a significant mass effect. Infarcts were seen in three patients and angiography showed vessel narrowing or occlusion in all the three patients. CT demonstrated isodense to hyperdense attenuation of primary sinus disease with evidence of bone destruction in all the cases of sinonasal origin. Primary parenchymal lesions showed heterogenous attenuation with predominantly low-density areas. Dural-based lesions showed isodense to hyperdense attenuation. Magnetic resonance imaging revealed isointense to hypointense signal intensity on both T(1)-weighted (T1W) and T(2)-weighted (T2W) images in all lesions of sinonasal origin and isolated dural-based mass lesions. Primary parenchymal lesions showed heterogenous signal intensity pattern with predominantly hypointense signal on T1W and hyperintense signal on T2W images. Diffusion weighted imaging, magnetic resonance spectroscopy, and perfusion-weighted imaging gave valuable ancillary information in these cases. Sinonasal disease with intracranial extension is the commonest pattern of aspergillus infection followed by intracranial mass lesions. Hyperdense sinonasal disease with bone destruction and intracranial extension on computed tomography, hypointense signal intensity of the lesions on T2W magnetic resonance images, presence of areas of restricted diffusion, decreased perfusion on perfusion-weighted imaging, and presence of hemorrhages are key to the imaging diagnosis of fungal infection.