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Potential of Gd-DTPA-mannan liposome particles as a pulmonary perfusion MRI contrast agent: an initial animal study
K Suga1, M Mikawa, N Ogasawara
1Department of Radiology, Yamaguchi University School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan.
Unlabelled:
Suga K, Mikawa M, Ogasawara N, et al. Potential of Gd-DTPA-mannan liposome particles as a pulmonary perfusion MRI contrast agent: An initial animal study. Invest Radiol 2001;36:136-145.
Rationale And Objectives:
A paramagnetic, particle-type MR contrast agent, (Gd-diethylenetriamine pentaacetic acid [DTPA]-mannan-cholesterol)-coated liposomes, was designed to localize in the lung by the mechanism of capillary blockade, and the potential of this agent for pulmonary perfusion MRI was experimentally investigated.
Methods:
Before and up to 60 minutes after slow injection of this contrast agent, MR images were sequentially acquired at 10-second intervals along the same transaxial plane of the lung by using a gradient-echo pulse sequence with a short echo time of 1.2 ms on a 1.5-T MR scanner. After the minimal dose for obtaining a sufficient lung enhancement effect was determined in five rabbits, the time course of the enhancement effect was evaluated in six dogs by arterial blood gas analysis. The efficacy of MRI for detecting perfusion defects was evaluated in seven other dogs with pulmonary embolism.
Results:
Normal lungs were dose-dependently enhanced by this agent, and with a 2.0 mL/kg dose, dependent lungs were enhanced by more than 201%, with an average half-life of the enhancement effect of 35.7 +/- 5.3 minutes. With less than this dose (1.0-1.5 mL/kg), all of the embolized lung portions were clearly identified as perfusion defects. The prolonged enhancement effect allowed the acquisition of subsequent multisectional lung images, thus facilitating the assessment of anatomic location and extent of the perfusion defects. The reduction of PaO2 in room air after injection was within 5 mm Hg in both normal and embolized animals.
Conclusions:
These initial, experimental results show that paramagnetically labeled liposome particles may be a successful MR contrast agent for pulmonary perfusion imaging.
Insights
This study shows that liposome particles with gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) can be used as a pulmonary perfusion MRI contrast agent. The agent effectively identified lung perfusion defects in an animal model.
Area of Science:
- Radiology
- Medical Imaging
- Nanotechnology
Background:
- Pulmonary perfusion imaging is crucial for diagnosing lung conditions.
- Developing effective MRI contrast agents for lung imaging remains a challenge.
Purpose of the Study:
- To investigate the potential of novel paramagnetic liposome particles as a pulmonary perfusion MRI contrast agent.
- To assess the agent's ability to localize in the lung via capillary blockade for enhanced imaging.
Main Methods:
- Liposome particles coated with Gd-DTPA-mannan-cholesterol were designed.
- MR images were acquired sequentially in rabbits and dogs after contrast agent injection.
- Pulmonary embolism was induced in dogs to evaluate MRI's efficacy in detecting perfusion defects.
Main Results:
- The contrast agent demonstrated dose-dependent enhancement in normal lungs.
- A dose of 2.0 mL/kg resulted in over 201% enhancement with a half-life of 35.7 minutes.
- Perfusion defects were clearly identified in embolized lung portions at lower doses, with minimal impact on blood oxygen levels.
Conclusions:
- Paramagnetically labeled liposome particles show promise as a successful MR contrast agent for pulmonary perfusion imaging.
- The agent's prolonged enhancement effect aids in assessing the extent and location of perfusion defects.