Focal liver lesion detection and characterization: comparison of non-contrast enhanced and SPIO-enhanced diffusion-weighted single-shot spin echo echo planar and turbo spin echo T2-weighted imaging.
OBJECTIVE
To compare lesion conspicuity and image quality between single-shot spin echo echo planar imaging (SS SE-EPI) before, immediately and 5min after intravenous (IV) injection of superparamagnetic iron oxide (SPIO) for detecting and characterizing focal liver lesions (FLLs).


METHODS
Twenty-five patients suspected for colorectal liver metastases were prospectively included. Lesion detection and characterization were compared between all SS SE-EPI and T2-weighted turbo spin echo (T2w TSE) sets (two-sided Fisher's exact test). Image quality and lesion conspicuity were compared for SS SE-EPI sets using rank order statistic (RIDIT). Reference standard comprised of surgery, biopsy and/or follow-up.


RESULTS
Reference standard demonstrated 18 benign and 43 malignant FLLs. Best lesion detection (p<0.05) was achieved with non-contrast-enhanced SS SE-EPI. Lesion characterization was best using all T2w TSE sequences. Best image quality and lesion conspicuity (p<0.05) was achieved with non-contrast-enhanced SS SE-EPI.


CONCLUSIONS
Non-contrast-enhanced SS SE-EPI was best for lesion detection. SS SE-EPI sequences were not useful for lesion characterization (differentiation between benign and malignant lesions). Unenhanced SS SE-EPI did not allow differentiation especially as many benign FLLs were hyperintense on the highest b-value images. Combining unenhanced and SPIO-enhanced SS SE-EPI performed better but still was not clinically useful due to variable degree of uptake and vascular pooling of SPIO for (especially) benign FLLs. T2w TSE with SPIO-enhancement was needed for characterization.
Coenegrachts
Kenneth
K
Department of Radiology, AZ St.-Jan AV, Ruddershove 10, B-8000 Bruges, Belgium. kenneth.coenegrachts@azbrugge.be
Matos
Celso
C
ter Beek
Léon
L
Metens
Thierry
T
Haspeslagh
Marc
M
Bipat
Shandra
S
Stoker
Jaap
J
Rigauts
Hans
H
D015179:Colorectal Neoplasms / Q000175:diagnosis*; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D052203:Ferrosoferric Oxide; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D003287:Contrast Media; C427127:superparamagnetic blood pool agent; D052203:Ferrosoferric Oxide