Use of Ultra-high Field MRI in Small Rodent Models of Polycystic Kidney Disease for In Vivo Phenotyping and Drug Monitoring

The overall goal of the following experiment is to obtain phenotypic information and to monitor interventions of rodent models of polycystic kidney disease using ultra high field magnetic resonance imaging. This is achieved by reaching a surgical level of anesthesia in the animal to ensure that high quality images can be acquired. It is also important to use animal holders to secure the animal in place and to prevent motion.

During the MRI experiment, it is important to select and acquire the proper image sequence and parameters based on the specific research aims To ensure animal safety, the animal's body temperature and respiratory rate should be closely monitored throughout the procedure. Ultimately, the acquired images are analyzed to detect phenotypic changes or to determine if there is a treatment effect. This procedure allows for in vivo phenotypical characterization and drug monitor in animal models of polycystic kidney disease or PKD by using ultra high field magnetic resonance imaging.

This technique is used to characterize phenotypes of new disease models and to monitor therapeutic interventions. A major advantage of this inbivo imaging method is that it enables longitudinal studies to repeatedly use the same animal, which subsequently reduces the total number of animals that are required for an experiment. Before starting the scan, ensure that the heater is in the off position.

Then select the mini imaging gradient in the scanner software, and obtain the 38 millimeter radio frequency or RF coil and mini imaging holder. Install the variable temperature assembly onto the central bore of the mini imaging holder After anesthetizing the animal as described in the text protocol, remove any metal tags, apply vet ointment to the animal's eyes to prevent dryness while under anesthesia, and then place the animal on a holder with its nose inserted into a nose cone. Insert rectal thermometer to monitor the animal's body temperature.

Next, attach a balloon respiratory pressure sensor to the animal's abdomen To monitor respiration rate, maintain a respiration rate of 40 breaths per minute by periodically adjusting the isof fluorine concentration. Then to prevent motion during the MR, I use animal holders to secure the animal in place. Finally, secure the animal at the center of the RF coil and carefully place the coil with the animal into the MRI scanner.

Before starting the experiments, adjust the air temperature and airflow rate to maintain a body temperature of 35 to 37 degrees Celsius throughout the experiments. Before starting the scan, minimize RF power and maximize the signal to noise ratio by tuning and matching the RF coil. To do this, click the tools icon to open the spectrometer control tool in the spectrometer control tool.

First click acquisition, followed by wobble. Then an acquisition reconstruction window will open displaying the wobble curve. Next, make slight adjustments to the tuning and matching capacitors until the reflected RF power is minimized.

The wobble curve should show a minimum at the vertical axis and be positioned at zero on the horizontal axis. Finally, click the stop button in the acquisition reconstruction window when the calibration of the coil has been achieved. To set the proper geometry for the imaging, acquire scout images in three orthogonal planes, axial, coronal, and sagittal by using intra gate fast, low angle shot or IG flash.

Start the scan with a traffic light. This will automatically calibrate the RF channel, shim the magnet. Set the carrier frequency on resonance for water and adjust the receiver gain.

Next, acquire images in 2D multis slice or 3D mode for anatomic studies. To shorten the experimental time, keep the field of view between 2.56 and 3.2 centimeters. To avoid wraparound artifacts, to ensure the data are collected during the animal's quiet period, keep the animal's respiratory rate at 30 breaths per minute.

For abdominal images, carefully select the repetition time and number of slices according to the animal's respiration cycle. To do this, use a turbo rapid acquisition with relaxation enhancement or rare sequence and acquire 11 to 19 coronal slices with a repetition time of 1500 milliseconds. After the scan is complete, remove the animal from the scanner, place it onto a heated pad and monitor it until it becomes ambulatory.

After recovery, return the animal to the cage and monitor for at least one hour before returning it to the animal facility. Here is a T two weighted image from the abdomen of a polycystic kidney disease or PKD mouse model that was acquired with U-H-F-M-R-I. Many cysts can be seen in the diseased kidney and liver.

U-H-F-M-R-I enables calculation of myocardial volume by using the myocardial tissue of the mouse heart in each slice. This allows researchers to evaluate cardiovascular function and possibly other cardiac complications in the disease model. In addition, many cies have been associated with brain malformations among other defects using U-H-F-M-R-I.

Arachnoid cysts are apparent in the area of the fourth ventricle in A PKD, mouse brain, U-H-F-M-R. I can also provide detailed embryonic information from pregnant female rodents with PKD, allowing researchers to detect embryonic lethality to assess phenotypic abnormalities and to determine at what embryonic stage they occurred for such embryos are shown here. Finally, ultra high field MRI allows for in vivo treatment monitoring of rodent PKD models.

Here imaging was acquired at three different ages for an animal in the control group and for an animal. In the 1D amino eight D arginine vasopressin treated group, We have just shown you how to use ultra high field magnetic resonance imaging for inbivo phenotypic characterization or drug monitor of small random models of polycystic kidney disease. While performing this experiment, it is important to remember that MRI is highly sensitive to motion.

To ensure the benefits of this technique, the animal must be secured, properly, kept under a surgical level of anesthesia, and continuously monitored throughout the procedure.