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Diffusion coefficients in abdominal organs and hepatic lesions: evaluation with intravoxel incoherent motion
1Department of Radiology, Faculty of Medicine, Tokyo Medical and Dental University, Japan.
Purpose:
To determine the true diffusion coefficients of abdominal organs and hepatic lesions with intravoxel incoherent motion (IVIM) echo-planar magnetic resonance (MR) imaging.
Materials And Methods:
Seventy-eight patients suspected of having hepatic lesions were examined with IVIM echo-planar MR imaging at 1.5 T. There were 77 hepatic masses (27 hepatocellular carcinomas, 10 metastatic tumors, eight hemangiomas, and 32 cysts) in the 78 patients. The true diffusion coefficient D and the perfusion fraction f were calculated and compared with the apparent diffusion coefficient (ADC).
Results:
Specific values of D were found for abdominal organs (liver, 0.72 x 10(-3) mm2/sec; spleen, 0.80 x 10(-3) mm2/sec; kidney, 1.38 x 10(-3) mm2/sec; gallbladder, 2.82 x 10(-3) mm2/sec) and for hepatic lesions (hepatocellular carcinoma, 1.02 x 10(-3) mm2/sec; metastasis, 1.16 x 10(-3) mm2/sec; hemangioma, 1.31 x 10(-3) mm2/sec; cysts, 3.03 x 10(-3) mm2/sec). The ADCs of solid organs and solid lesions were significantly higher than their D values, indicating a high contribution of perfusion to the ADCs.
Conclusion:
Perfusion contributes to the ADCs of abdominal organs and hepatic lesions. The D and f values are useful for the characterization of hepatic lesions.
Insights
Intravoxel incoherent motion (IVIM) magnetic resonance imaging quantifies true diffusion coefficients (D) and perfusion fractions (f) in abdominal organs and liver lesions. These IVIM parameters aid in differentiating hepatic lesions and understanding diffusion-weighted imaging (DWI) signal changes.
Area of Science:
- Radiology and Imaging Science
- Medical Physics
- Hepatobiliary Imaging
Background:
- Apparent diffusion coefficient (ADC) measurements in hepatic lesions are influenced by both true diffusion and microvascular perfusion.
- Intravoxel incoherent motion (IVIM) imaging offers a method to decouple these two components, providing true diffusion coefficient (D) and perfusion fraction (f) values.
- Accurate characterization of hepatic lesions is crucial for diagnosis and treatment planning.
Purpose of the Study:
- To determine the true diffusion coefficients (D) of abdominal organs and hepatic lesions using IVIM echo-planar MR imaging.
- To compare D and perfusion fraction (f) values with apparent diffusion coefficient (ADC) measurements.
- To assess the utility of IVIM parameters for characterizing hepatic lesions.
Main Methods:
- Seventy-eight patients with suspected hepatic lesions underwent 1.5 T IVIM echo-planar MR imaging.
- IVIM analysis was performed to calculate the true diffusion coefficient (D) and perfusion fraction (f).
- Calculated D and f values were compared with ADC values for 77 hepatic masses (including hepatocellular carcinoma, metastases, hemangiomas, and cysts) and abdominal organs.
Main Results:
- Specific D values were established for abdominal organs (liver, spleen, kidney, gallbladder) and hepatic lesions (hepatocellular carcinoma, metastasis, hemangioma, cysts).
- The ADCs of solid organs and solid hepatic lesions were significantly higher than their corresponding D values.
- This difference highlights the substantial contribution of microvascular perfusion to the ADC values in these tissues.
Conclusions:
- Microvascular perfusion significantly contributes to the ADC values of abdominal organs and hepatic lesions.
- The true diffusion coefficient (D) and perfusion fraction (f) derived from IVIM imaging are valuable for characterizing hepatic lesions.
- IVIM imaging provides a more comprehensive understanding of tissue microenvironment compared to conventional ADC mapping.