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Comparison of monopolar and bipolar diffusion weighted imaging sequences for detection of small hepatic metastases
Akihiro Furuta1, Hiroyoshi Isoda1, Rikiya Yamashita1
1Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
Objective:
To compare monopolar (MP) and bipolar (BP) diffusion weighted imaging (DWI) in detecting small liver metastases.
Materials And Methods:
Eighty-eight patients underwent 3-T MRI. The signal-to-noise ratios (SNR) of the liver parenchyma and lesions, the lesion-to-liver contrast-to-noise ratios (CNR), and the detection sensitivities were compared. The lesion distortion was scored (LDS) from 4 (no distortion) to 1 (excessive distortion), dichotomised as no-distortion and distortion, and the association between detected lesions for each reader in the MP or BP DWI group and the dichotomised lesion distortion degree was assessed.
Result:
Forty-six hepatic metastases were confirmed. The CNR with BP images showed significantly higher values than with MP (P=0.017). The detection sensitivities of the three readers were higher in the BP sequence than in MP, and one reader detected significantly more hepatic lesions with BP images (P=0.04). LDS was significantly improved with BP sequence (P=0.002). In the no-distortion group, excluding the MP DWI assessments of one reader, detection sensitivities were significantly higher than in the distortion group (P<0.001 and P=0.002, respectively).
Conclusion:
Reduced lesion distortion improves the detection of small liver metastases, and BP is more sensitive in detecting small liver metastases than MP DWI.
Insights
Bipolar (BP) diffusion weighted imaging (DWI) is more sensitive than monopolar (MP) DWI for detecting small liver metastases, with reduced lesion distortion significantly improving detection rates.
Area of Science:
- Medical Imaging
- Oncology
- Radiology
Background:
- Early detection of small liver metastases is crucial for effective cancer treatment.
- Diffusion weighted imaging (DWI) is a key MRI technique for liver lesion characterization.
- Monopolar (MP) and bipolar (BP) DWI sequences have different characteristics that may affect lesion detection.
Purpose of the Study:
- To compare the efficacy of monopolar (MP) and bipolar (BP) diffusion weighted imaging (DWI) in detecting small liver metastases.
- To evaluate the impact of lesion distortion on detection sensitivity.
Main Methods:
- Eighty-eight patients underwent 3-Tesla MRI with both MP and BP DWI sequences.
- Signal-to-noise ratios (SNR), contrast-to-noise ratios (CNR), and detection sensitivities were compared.
- Lesion distortion was scored and analyzed in relation to detection sensitivity.
Main Results:
- Bipolar (BP) DWI demonstrated significantly higher lesion-to-liver contrast-to-noise ratios (CNR) compared to monopolar (MP) DWI.
- Detection sensitivities for small liver metastases were higher with BP DWI across all readers.
- Reduced lesion distortion was significantly associated with improved detection sensitivity.
Conclusions:
- Bipolar (BP) DWI is more sensitive than monopolar (MP) DWI for detecting small liver metastases.
- Minimizing lesion distortion in DWI is critical for enhancing the detection of small hepatic lesions.
