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Unenhanced MR portography with a half-Fourier fast spin-echo sequence and time-space labeling inversion pulses:
Kotaro Shimada1, Hiroyoshi Isoda, Tomohisa Okada
1Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
Objective:
For this study, we aimed to selectively visualize the intrahepatic portal veins using 3D half-Fourier fast spin-echo (FSE) MR angiography (MRA) with a time-space labeling inversion pulse (T-SLIP) and to optimize the acquisition protocol.
Subjects And Methods:
Respiratory-triggered 3D half-Fourier FSE scans were obtained in 25 healthy adult subjects combined with two different T-SLIPs: one placed on the liver and the thorax to suppress signals of the liver parenchyma, hepatic veins, and abdominal arteries and the other on the lower abdomen to suppress the ascending signal of the inferior vena cava. One of the most important factors was the inversion time (TI) of the inversion pulse for the liver and thorax. Image quality was evaluated in terms of signal-to-noise ratio, contrast-to-noise ratio, and mean visualization scores at four different TIs: 800, 1,200, 1,600, and 2,000 milliseconds.
Results:
Selective visualization of the portal vein was successfully achieved in all volunteers, and anatomic variations were also seen in three subjects. A TI of 1,200 milliseconds was optimal in our protocol because it was sufficient for peripheral portal vein visualization and was most suitable for signal suppression of the hepatic veins and liver parenchyma.
Conclusion:
Half-Fourier FSE scanning with T-SLIPs enabled selective visualization of the portal vein without an exogenous contrast agent.
Insights
This study successfully visualized the intrahepatic portal vein using 3D half-Fourier fast spin-echo (FSE) MR angiography with time-space labeling inversion pulses (T-SLIPs). The optimized protocol achieved selective portal vein imaging without contrast agents.
Area of Science:
- Radiology
- Medical Imaging
- Vascular Imaging
Background:
- Accurate visualization of the intrahepatic portal vein is crucial for diagnosing liver diseases.
- Traditional MR angiography often requires exogenous contrast agents, which can have risks and limitations.
Purpose of the Study:
- To selectively visualize the intrahepatic portal veins using 3D half-Fourier FSE MR angiography (MRA) with T-SLIPs.
- To optimize the acquisition protocol for improved portal vein imaging.
Main Methods:
- Respiratory-triggered 3D half-Fourier FSE scans were performed on 25 healthy adults.
- Two T-SLIP techniques were employed to suppress surrounding tissues and vessels.
- Image quality was assessed at various inversion times (TI) to determine optimal parameters.
Main Results:
- Selective visualization of the portal vein was achieved in all subjects.
- An inversion time (TI) of 1,200 milliseconds was found to be optimal for peripheral portal vein visualization and signal suppression.
- Anatomic variations of the portal vein were observed in three subjects.
Conclusions:
- 3D half-Fourier FSE scanning with T-SLIPs provides effective selective visualization of the portal vein.
- This technique allows for contrast-agent-free MR angiography of the portal venous system.
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