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Original Research |
1 Department of Radiology, Klinikum rechts der Isar, Technische Universität
München, Ismaninger Str. 22, D-81675 Munich, Germany.
2 Siemens Medical Solutions, Erlangen, Germany.
OBJECTIVE. The purpose of this study was to compare the value of respiration-triggered diffusion-weighted (DW) single-shot echo-planar MRI (EPI) and five variants of T2-weighted turbo spin-echo (TSE) sequences in the diagnosis of hepatic metastasis.
MATERIALS AND METHODS. Fifty-two patients with extrahepatic primary malignant tumors underwent 1.5-T MRI that included DW EPI and the following variants of T2-weighted TSE techniques: breath-hold fat-suppressed HASTE, breath-hold fat-supressed TSE, respiration-triggered fat-suppressed TSE, breath-hold STIR, and respiration-triggered STIR. Images were reviewed independently by two blinded observers who used a 5-point confidence scale to identify lesions. Results were correlated with surgical and histopathologic findings and follow-up imaging findings. The accuracy of each technique was measured with free-response receiver operating characteristic analysis.
RESULTS. A total of 118 hepatic metastatic lesions (mean diameter,
12.8 mm; range, 3–84 mm) were evaluated. Accuracy values were higher
(p < 0.001) with DW EPI (0.91–0.92) than with the
T2-weighted TSE techniques (0.47–0.67). Imaging with the HASTE sequence
(0.47–0.52) was less accurate (p < 0.05) than imaging with
the breath-hold TSE, breath-hold STIR, respiration-triggered TSE, and
respiration-triggered STIR sequences (0.59–0.67). Sensitivity was higher
(p < 0.001) with DW EPI (0.88–0.91) than with T2-weighted
TSE techniques (0.45–0.62). For small (
10 mm) metastatic lesions
only, the differences in sensitivity between DW EPI (0.85) and T2-weighted TSE
techniques (0.26–0.44) were even more pronounced.
CONCLUSION. DW EPI was more sensitive and more accurate than imaging
with T2-weighted TSE techniques. Because of the black-blood effect on vessels
and low susceptibility to motion artifacts, DW EPI was particularly useful for
the detection of small (
10 mm) metastatic lesions.
Keywords: detection diffusion MRI echo-planar imaging hepatic metastasis
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