[Differentiation of serous and purulent fluids in vitro and in vivo by means of diffusion-weighted MRI].
OBJECTIVE
The aim of this study was to test the feasibility for differentiation of serous fluid collections and abscess fluid with diffusion-weighted imaging and to compare three different diffusion sequences.


METHODS
Thirteen puncture samples (6 serous, 7 purulent) and 19 patients with either serous fluid collections (n = 12) or abscesses (n = 7) were examined with diffusion-weighted spin-echo (SE), stimulated-echo (STE), and fatsuppressed SE (SE-SPIR) sequences. For in vitro studies 4 different b-factors (0, 87, 355, 798 s/mm2 in SE and SE-SPIR and 0, 51, 204, 460 s/mm2 in STE) were chosen and the apparent diffusion coefficient (ADC) was calculated. For in vivo measurements identical sequences with two b-factors (0.598 s/mm2 in SE and SE-SPIR and 0.360 s/mm2 in STE) were applied and the normalized signal attenuation was calculated. A navigator-echo technique and peripheral pulse triggering was used for motion artifact reduction.


RESULTS
The in vitro study yielded an ADC of serous fluid, which was close to that of free water, whereas for purulent fluid a significantly lower ADC was calculated. During in vivo examinations, serous fluids showed a strong signal attenuation (down to 22-32% of basic value) compared to a minor signal attenuation in purulent fluids (down to 86-94% of basic value) (p < 0.05).


CONCLUSIONS
In summary, with all three investigated diffusion schemes serous and purulent fluids can be clearly differentiated.
Spüntrup
E
E
Klinik für Radiologische Diagnostik, Medizinische Einrichtungen der RWTH Aachen. spuenti@rad.rwth-aachen.de
Bücker
A
A
Adam
G
G
van Vaals
J J
JJ
Günther
R W
RW
D000038:Abscess / Q000175:diagnosis*; D000293:Adolescent; D000328:Adult; D000368:Aged; D003627:Data Interpretation, Statistical; D003937:Diagnosis, Differential; D005122:Exudates and Transudates / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013492:Suppuration / Q000175:diagnosis*