Figure 1
Lung CT examination
Brain aspergillosis forming an abscess
SectionNeuroradiology
Case TypeClinical Cases
AuthorsGerukis T, Voultsinou D, Anastasiadou K, kalpakidis V, Palladas P
Connected authors
64 years, female
Clinical History
A 64 years old female was evaluated for headaches. The patient underwent CT and MR examination of the brain
Imaging Findings
A 64 years old female evaluated for headaches. The patient underwent CT and MR examination.
CT examination, at pre-contrast scan (Figure 1a), revealed a left tempo-occipital hypodence inchomogeneous lesion. Post-contrast scan showed (Figure 1b) a peripheral ring like enhancement of the lesion and associated peripheral edema.
On conventional magnetic resonance examination, the lesion presented at FLAIR (Figure 2a), T2 (Figure 2b) and at T1 weighted sequences (Figure 2c) with central cystic region and peritumoral edema. At T1 post-contrast scan (Figure 2d) a rim -like peripheral contrast enhancement of the lesion was observed.
MR diffusion weighted image (DW1-Figure 3a) demonstrated signal hyperintensity (increased restriction of diffusion) of the cystic part of the lesion whereas perfusion weighted imaging (PW1-Figure 3c) visualized no vascularity. The Imaging findings were compatible with brain abscess. The ADC values of the lesion exclude tuberculoma which presents with ADC values similar to brain parenchyma.
Due to previous history (diabetes mellitus, obstructive lung disease, and previous tbc infection) a lung CT was performed. Brochiectatic foci (Figure 4a) and a thin walled cavitary lesion (Figure 4b) at the right upper lung lobe compatible with TBC cavity were depicted. Within the lesion a movable nodule (Figure 5) compatible with mycetoma observed.
The above mentioned diffusion and perfusion findings, CT findings, in accordance with the negative results of stereotactic biopsy for neoplasia were compatible with aspergillous abscess. The ADC values of the lesion exclude tuberculoma which presents with ADC values similar to brain parenchyma.
CT examination, at pre-contrast scan (Figure 1a), revealed a left tempo-occipital hypodence inchomogeneous lesion. Post-contrast scan showed (Figure 1b) a peripheral ring like enhancement of the lesion and associated peripheral edema.
On conventional magnetic resonance examination, the lesion presented at FLAIR (Figure 2a), T2 (Figure 2b) and at T1 weighted sequences (Figure 2c) with central cystic region and peritumoral edema. At T1 post-contrast scan (Figure 2d) a rim -like peripheral contrast enhancement of the lesion was observed.
MR diffusion weighted image (DW1-Figure 3a) demonstrated signal hyperintensity (increased restriction of diffusion) of the cystic part of the lesion whereas perfusion weighted imaging (PW1-Figure 3c) visualized no vascularity. The Imaging findings were compatible with brain abscess. The ADC values of the lesion exclude tuberculoma which presents with ADC values similar to brain parenchyma.
Due to previous history (diabetes mellitus, obstructive lung disease, and previous tbc infection) a lung CT was performed. Brochiectatic foci (Figure 4a) and a thin walled cavitary lesion (Figure 4b) at the right upper lung lobe compatible with TBC cavity were depicted. Within the lesion a movable nodule (Figure 5) compatible with mycetoma observed.
The above mentioned diffusion and perfusion findings, CT findings, in accordance with the negative results of stereotactic biopsy for neoplasia were compatible with aspergillous abscess. The ADC values of the lesion exclude tuberculoma which presents with ADC values similar to brain parenchyma.
Discussion
Aspegillus fumigatus usually appears as an opportunistic infection and reaches the brain most commonly hematogenously from a pulmonary infection. Severe hematologic disease involves more than other sources of immuno-suppression.
Aspergillus is an angioinvasive, cerebral infection which leads to acute infarcts that may have hemorrhages within them. These areas of infarct can progress to infectious cerebritis or abscess. An atypical infection distribution may also be observed at sites that are rarely affected by other infectious organisms.
It may manifest as a single or multiple lesions. On CT, non-specific poorly circumscribed areas of subtle hypodensity are seen. There is a little or no mass effect. The lesions often appear hyperintense on T2-weighted or proton-density MR images, and exhibit restricted diffusion on diffusion-weighted MR images, finding compatible with abscess. The lesions generally exhibit no enhancement, or else only subtle peripheral enhancement, on both CT and MRI. Ring enhancement can occur if abscesses form, but this is uncommon because lesions rarely become "walled off" in severely immunocompromised patients. Despite the fact that leptomeningeal inflammation and ventriculitis are commonly found at autopsy, leptomeningeal and ependymal enhancement are rarely seen in imaging studies. Dural enhancement is often visible, however, if the infection has spread directly from the paranasal sinuses. The infection will demonstrate rapid progression by size and number of lesions on repeat imaging.
Few entities would be associated with a hemorrhagic mass as well as multifocal lesions of bright diffusion-weighted signal. lymphoma, septic emboli and abscesses can also occur in an analogous manner.
Brain aspergillosis is an opportunistic infection that may manifest as a solitary abscess or/and vascular involvement. CT is the first line examination whereas MRI is the method of choice with increased rates of sensitivity for the evaluation of brain abscesses and the use of diffusion and perfusion techniques increases the specificity rates.
Aspergillus is an angioinvasive, cerebral infection which leads to acute infarcts that may have hemorrhages within them. These areas of infarct can progress to infectious cerebritis or abscess. An atypical infection distribution may also be observed at sites that are rarely affected by other infectious organisms.
It may manifest as a single or multiple lesions. On CT, non-specific poorly circumscribed areas of subtle hypodensity are seen. There is a little or no mass effect. The lesions often appear hyperintense on T2-weighted or proton-density MR images, and exhibit restricted diffusion on diffusion-weighted MR images, finding compatible with abscess. The lesions generally exhibit no enhancement, or else only subtle peripheral enhancement, on both CT and MRI. Ring enhancement can occur if abscesses form, but this is uncommon because lesions rarely become "walled off" in severely immunocompromised patients. Despite the fact that leptomeningeal inflammation and ventriculitis are commonly found at autopsy, leptomeningeal and ependymal enhancement are rarely seen in imaging studies. Dural enhancement is often visible, however, if the infection has spread directly from the paranasal sinuses. The infection will demonstrate rapid progression by size and number of lesions on repeat imaging.
Few entities would be associated with a hemorrhagic mass as well as multifocal lesions of bright diffusion-weighted signal. lymphoma, septic emboli and abscesses can also occur in an analogous manner.
Brain aspergillosis is an opportunistic infection that may manifest as a solitary abscess or/and vascular involvement. CT is the first line examination whereas MRI is the method of choice with increased rates of sensitivity for the evaluation of brain abscesses and the use of diffusion and perfusion techniques increases the specificity rates.
Differential Diagnosis List
Brain aspergillosis forming an abscess
Final Diagnosis
Brain aspergillosis forming an abscess
References
[1] Ashdown BC, Tien RD, Felsberg GJ (1994) Aspergillosis of the brain and paranasal sinuses in immunocompromised patients: CT and MR imaging findings. Am J Roentgenol 162: 155-159. (PMID: 8273655)
[2] DeLone DR, Goldstein RA, Petermann G, Salamat MS, Miles JM, Knechtle SJ, Brown WD (1999) Disseminated Aspergillosis Involving the Brain: Distribution and Imaging Characteristics. Am J Neuroradiol 20:1597-1604. (PMID: 10543627)
[3] Patterson TF, Kirkpatrick WR, White M, Hiemenz JW, Wingard JR, Dupont B, Rinaldi MG, Stevens DA, Graybill JR (2000) Invasive Aspergillosis: Disease Spectrum, Treatment Practices, and Outcomes. Medicine 79(4): 250-260.
Case information
| URL: | https://www.eurorad.org/case/6639 |
| DOI: | 10.1594/EURORAD/CASE.6639 |
| ISSN: | 1563-4086 |
Figure 3
Diffusion and perfusion magnetic resonance imaging
Figure 3a. MRI difussion weighted image (b-value: 1000), signal hyperintensity of the cystic part of the lesion: restricted diffusion
Figure 3b. ADC map, confirms restricted diffusion of the cystic contents. ADC values ranging between 0.45-.65x10-3 mm2/sec
Figure 3c. CBV Perfusion map, no vascularity of the lesion
Figure 4
Computed tomography examination.
Figure 1a. Computed tomography examination, axial view.
Pre-contrast scan, revealed a left tempo-occipital hypodence inchomogeneous lesion.
Figure 1b. Computed tomography examination, axial view, post-contrast scan.
Peripheral ring- like enhancement was observed with associated peripheral edema.
Figure 5
Conventional magnetic resonance examination axial views
Figure 2a. FLAIR sequence.
The central cystic region visualixed with low signal intensity and large surrounding area of
hyperintensity -peritumoral vasogenic edema
Figure 2b. T2 sequences with central cystic region and and large surrounding area of
hyperintensity - peritumoral edema
Figure 2c. Magnetic resonance examination axial view.
The lesion presents at T1 sequence, with central cystic region and large surrounding area of
hyporintensity-peritumoral edema .
Figure 2d. T1 post-contrast scan. Aperipheral thin rim of contrast enhancement is observed
Diffusion and perfusion magnetic resonance imaging
Figure 3a. MRI difussion weighted image (b-value: 1000), signal hyperintensity of the cystic part of the lesion: restricted diffusion
Figure 3b. ADC map, confirms restricted diffusion of the cystic contents. ADC values ranging between 0.45-.65x10-3 mm2/sec
Figure 3c. CBV Perfusion map, no vascularity of the lesion
Computed tomography examination.
Figure 1a. Computed tomography examination, axial view.
Pre-contrast scan, revealed a left tempo-occipital hypodence inchomogeneous lesion.
Figure 1b. Computed tomography examination, axial view, post-contrast scan.
Peripheral ring- like enhancement was observed with associated peripheral edema.
Conventional magnetic resonance examination axial views
Figure 2a. FLAIR sequence.
The central cystic region visualixed with low signal intensity and large surrounding area of
hyperintensity -peritumoral vasogenic edema
Figure 2b. T2 sequences with central cystic region and and large surrounding area of
hyperintensity - peritumoral edema
Figure 2c. Magnetic resonance examination axial view.
The lesion presents at T1 sequence, with central cystic region and large surrounding area of
hyporintensity-peritumoral edema .
Figure 2d. T1 post-contrast scan. Aperipheral thin rim of contrast enhancement is observed