Brain Abscess Apparent Diffusion Coefficient is Associated With Microbial Culture Yields

Abstract

Background: Obtaining pus for microbial cultures is one of the surgical aims in patients with brain abscess. Predictors of microbial yields are necessary as they help in treatment planning. Purpose: To investigate the relationship between microbial culture yields of brain abscesses and their apparent diffusion coefficient (ADC) values and clinical characteristics. Study Type: Retrospective. Subjects: Eighty-four patients diagnosed with brain abscess by surgery and histopathology (59 with positive abscess cultures). Field Strength/Sequence: Diffusion-weighted, T2-weigthed, and contrast-enhanced T1-weighted imaging at 1.5 T and 3 T. Assessment: Contrast-enhanced T1-weighted images were co-registered to ADC maps. Three neuroradiologists determined abscess imaging characteristics (distribution, location, and ventricular rupture), and two measured abscess volumes and ADC values. Clinical characteristics collected included sex, age, fever, underlying diseases, infection sources, white blood cell count, percentage of segmented neutrophils, C-reactive protein level, regimen and duration of empirical antibiotics, and types of surgery. Statistical Tests: Interobserver differences were assessed with Fleiss kappa and intraclass correlation coefficients. The differences in clinical and imaging factors between the positive and negative culture groups were compared with Chi-square analysis or Student's t test. All factors were subjected to multivariable logistic regression analysis to assess their associations with microbial culture yields, and factors with statistical significance were evaluated with receiver operating characteristic curve analysis to assess their diagnostic performance in discriminating the two groups. Results: Mean ADC (×10 −6 mm 2 /s) of culture-negative abscesses (841 AE 173) was significantly higher (P < 0.05) than that of culture-positive abscesses (536 AE 90). On multivariable analysis, mean ADC was the only significant factor (P < 0.05) related to culture yields. With 660 as the cutoff value, the sensitivity, specificity, and accuracy of ADC for discriminating culture yields were 93.2%, 88.0%, and 91.7%, respectively. Data Conclusion: ADC could be used to discriminate between culture-positive and culture-negative abscesses. Evidence Level: 4 Technical Efficacy: Stage 2

Peritumoral Brain Edema in Metastases May Be Related to Glymphatic Dysfunction

“…Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) are quantitative metrics derived from DTI for water diffusivity measurement. In addition to tumor cellularity ( 20 ) and fluid viscosity ( 21 ), they may also reflect the volume and flow directionality of the tumor interstitial fluid ( 12 ). The ALPS index, recently proposed by Taoka et al, is another quantitative diffusion metric derived from DTI ( 22 ).…”

Brain abscess in immunocompetent patients: recent findings

“…The diffusion restriction in the central liquid portion of a pyogenic abscess is related to the viscosity of the pus and the presence of neutrophils. A recent study showed a lower Apparent Diffusion Coefficient (ADC) on positive culture abscesses than on negative ones [21], suggesting a correlation between ADC and bacterial culture yields. Thus, the ADC map could guide a needle biopsy if the lesions are multiple.…”

Editorial for “Apparent Diffusion Coefficient of Brain Abscesses Predicts Microbial Culture Yields”

“…In this issue of JMRI, Toh et al 7 investigated whether mean ADC values of cerebral abscesses could contribute to treatment planning through predicting whether the abscess may be culture positive or negative. For this purpose, they compared 84 cerebral abscesses (59 of them were culturepositive and 25 culture-negative) in terms of mean ADC values and found that the ADC values of culture-positive abscesses (841 AE 173 × 10 −6 mm 2 /sec) were significantly higher than ADC values of culture-negative ones (536 AE 90 × 10 −6 mm 2 /sec).…”

“…Lee et al 1 reported that the abscess culture of a cerebral abscess with focal diffusion restriction was sterile while Streptococcus intermedius was found in the abscess culture of another case with heterogeneous diffusion. For these reasons, the results of Toh et al 7 need to be verified by prospective studies to be conducted using larger series with more homogeneous cases (eg, cases sub-grouped by active agents such as bacterial, fungal, or parasitic agents, by the abscess age if possible, by comorbid diseases or host immunity, etc. ).…”