Diffusion-weighted imaging in the assessment of brain abscesses therapy.
OBJECTIVE
Surgically or conservatively treated brain abscesses may resolve, or pus may re-accumulate, requiring further intervention or treatment change. We hypothesized that diffusion-weighted (DW) imaging is useful in depicting features of abscesses related to therapeutic success or failure.


METHODS
Conventional contrast-enhanced T1- and T2-weighted imaging and DW imaging were performed in seven patients (aged 30-69 years) with proved pyogenic brain abscesses. The center of the abscess was qualitatively and quantitatively analyzed at initial and follow-up imaging in all patients. We correlated the signal intensity on trace DW images and the apparent diffusion coefficients (ADCs) with the clinical and laboratory data, particularly with respect to treatment failure and repeat therapy.


RESULTS
Surgical drainage was performed in six patients; one patient was treated with only antibiotics. All abscess cavities initially had high signal intensity (restricted diffusion) on DW images, with a mean ADC value of 0.52 x 10 (-3)mm (2)/s. Low signal intensity at DW imaging with high ADC were seen on follow-up images in the patient receiving medication and in four patients in whom the abscesses were drained; this correlated with a good therapeutic response. Two patients underwent drainage; their second follow-up DW images showed areas of high signal intensity and low ADC values suggesting re-accumulation of pus. Increased C-reactive protein level and WBC count correlated well with DW image findings.


CONCLUSIONS
DW imaging was superior to conventional MR imaging in evaluating the success or failure of abscess therapy. Restricted diffusion in a drained abscess corresponded to pus.
Department of Radiology, Neuroradiology Section, University Hospital, Vienna, Austria.
Fabiola W
FW
Cartes-Zumelzu
Ioannis
I
Stavrou
Mauricio
M
Castillo
Edith
E
Eisenhuber
Engelbert
E
Knosp
Majda M
MM
Thurnher
D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001922:Brain Abscess / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D002097:C-Reactive Protein / Q000378:metabolism; D038524:Diffusion Magnetic Resonance Imaging / Q000592:standards; D004322:Drainage; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007958:Leukocyte Count; D008279:Magnetic Resonance Imaging / Q000592:standards; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence
D000900:Anti-Bacterial Agents; D002097:C-Reactive Protein