====== Brain abscess magnetic resonance imaging ======

{{rss>https://pubmed.ncbi.nlm.nih.gov/rss/search/1PAjVVEin27NaEPhW95axar6f3W9h9kGK3tOs4uc39ciz0z9LR/?limit=15&utm_campaign=pubmed-2&fc=20240202152324}}
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Fortunately, [[magnetic resonance imaging]] is usually able to convincingly make the [[brain abscess diagnosis]], distinguishing abscesses from other ring-enhancing lesions.

MRI is more sensitive than [[CT]]. Although peripherally-enhancing lesions may be non-specific by imaging, [[Diffusion-weighted magnetic resonance imaging]]s (less commonly [[MR spectroscopy]]) showing central [[restricted diffusion]] is critical for suggesting the diagnosis of a [[brain abscess]].
((https://radiopaedia.org/articles/brain-abscess-1#:~:text=A%20brain%20abscess%20is%20a,radiological%20identification%20and%20rapid%20treatment.))

====== T1 ======

{{::brain_abscess_case_reports_from_the_general_university_hospital_alicanted.jpg?200|}}

central low [[intensity]] ([[hyperintense]] to [[CSF]])

peripheral low intensity ([[vasogenic edema]]) 

[[ring enhancement]] 

[[ventriculitis]] may be present, in which case [[hydrocephalus]] will commonly also be seen

===== T2-weighted magnetic resonance imaging sequence =====
On [[T2-weighted magnetic resonance imaging sequence]], the [[brain abscess]] is [[hyperintense]] and the surrounding [[capsule]] is [[hypointense]]. There is extensive surrounding [[edema]] in most cases. The finding of a [[capsule]] that is hypointense on a [[T2]]-weighted image and mildly [[hyperintense]] on a T1-weighted image is suggestive of an abscess capsule.

{{::captura_de_pantalla_2024-02-02_a_las_21.42.37.jpg?200|}}



===== DWI/ADC =====

high DWI signal is usually present centrally 

represents true restricted diffusion.

peripheral or patchy restricted diffusion may also be seen; this finding is however not as constant as one may think, with up to half of the rim-enhancing lesions demonstrating some restriction not proving to be abscesses.

in some immunocompromised states, central content may not diffusion restrict

{{::brain_abscess_case_reports_from_the_general_university_hospital_alicantec.jpg?300|}}

The [[DWI]] shows often hyperintensity (restriction), (not reliable).

Diffusion-weighted imaging (DWI) is widely appreciated as an indispensable tool in the examination of the central nervous system. It is considered useful not only for the detection of [[acute ischemic stroke]] but also for the characterization and differentiation of [[brain tumor]]s and [[brain abscess]].



===== T2-FLAIR magnetic resonance imaging sequence =====
[[T2-FLAIR magnetic resonance imaging sequence for brain abscess]]

===== SWI =====

low-intensity rim 

complete in 75% 

smooth in 90%

mostly overlaps with contrast-enhancing rim

dual rim sign: a hyperintense line located inside the low-intensity rim 

===== MR perfusion =====
rCBV is reduced in the surrounding edema cf. to both normal white matter and tumor edema seen in high-grade gliomas.

===== Proton magnetic resonance spectroscopic imaging =====

Elevated peaks are seen corresponding to [[lipid]]s/[[lactate]], [[succinate]], [[acetate]], and [[amino acid]]s ([[alanine]], [[valine]], [[leucine]], and [[isoleucine]]).

[[Proton magnetic resonance spectroscopic imaging]] (PMRS) has high sensitivity and specificity for the detection of pyogenic [[brain abscess]] and the categorization of bacteria. But the metabolite patterns failed to evaluate the etiology of disease when the culture results are sterile. 

Based on metabolite resonances, PMRS can detect slow growing and fastidious organisms and classify them into aerobic and anaerobic bacteria which are difficult to culture by conventional method. It can categorize microorganisms even in culture sterile samples with rational sensitivity and specificity which may allow early choice of targeted therapy
((Bajpai A, Prasad KN, Mishra P, Gupta RK, Singh AK, Ojha BK. Multimodal approach for diagnosis of bacterial etiology in brain abscess. Magn Reson Imaging. 2014 Feb 18. pii: S0730-725X(14)00058-7. doi: 10.1016/j.mri.2014.02.015. [Epub ahead of print] PubMed PMID: 24661636.)).