Getting great resultswith Fenestra® nano-emulsions
Fenestra® nano-emulsions provide long-lasting contrast
enhancement for a wide range of applications in preclinicalcomputed tomography and molecular imaging.

Using Fenestra®

Storage and General Use

The guidelines and recommendations in this publication
are provided to help you optimize image quality andcomply with established regulations for animal studies.

Fenestra® contrast agents are non-toxic, non-radioactive,and do not contain active or biological products. Special
care is NOT required for storage, handling, or disposal.
However, you should wear goggles and disposable gloves
as well as protect clothing whenever you use Fenestra®.

Fenestra® LC and VC
Because of their comparatively long and stable in vivo
residence times, Fenestra® contrast agents can be used
to access anatomy and function in a wide range of
microCT imaging applications. Prolonged enhancement of
the entire hepatobiliary system is possible from a single
intravenous administration of Fenestra® LC, while theintravascular formulation of Fenestra® VC provides
superior vascular characterization and enables 4D
cardiac imaging.
Fenestra® LC enables visualization of the hepatobiliary
system and liver function by mimicking chylomicron remnants and localizing contrast-producing lipids into theliver’s parenchyma. In normal animals, hepatic contrast
enhancement lasts for up to several hours after injection.
®

®

Fenestra VC is a refined version of Fenestra LC in
which the surface of the lipid emulsion particles is modified to alter recognition of the particle by the receptors
on the hepatocytes that are responsible for uptake into
the liver. This delayed uptake produces contrast enhancement of the entire vascular system that can last forseveral hours. Fenestra® VC remains intravascular as
long as the endothelial integrity of the vessel is maintained. Like its liver-selective counterpart, Fenestra® VC
is eventually metabolized and eliminated through thehepatobiliary system.

6Storage
Always store Fenestra® at room temperature. Refrigeration is NOT recommended. Even partial freezing, which
is likely to cause phase separation, can render the product ineffective as well as toxic. Do NOT transfer to any
other container.

Expiry Date
Check the expiration date prior to administration. Do NOT
use expired Fenestra®.

Appearance
Examine the liquid prior to use. Fenestra® should appear
as a homogenous white or slightly off-white milky fluid,
without any solids or separation into distinct liquidphases. Do NOT use if the formulation appears to haveseparated into oil and water phases or appears to havesolidified.

Usage
Record the date of first entry into the vial prior to use.
Discard the remaining material 30 days after the firstentry. Do NOT dilute or combine with any other product.

Unadulterated Fenestra® should be injected directly.
Disinfect the vial with an alcohol swab before each usage.

DosageFenestra® is typically administered intravenously via alateral tail vein. CT enhancement profiles of Fenestra®
will vary with dose. Refer to review article MicroCT liver
contrast agent enhancement over time, dose, and mousestrain (Mol Imaging Biol. 2008 Mar-Apr;10(2):114-20. doi:
10.1007/s11307-007-0128-x. Epub 2008 Jan 16 available
at http://www.ncbi.nlm.nih.gov/pubmed/18204990)

Preparation
Mix Fenestra® by gentle inversion of the vial before administration. Avoid shaking, which can create air bubbles. If
the agent is not used within five to ten minutes of drawing
the dose, the contents of the syringe should be remixed
by gentle inversion prior to injection. You should be awarethat it can be difficult to see bubbles in Fenestra®, which
is opaque.

Elimination
Fenestra® is normally eliminated in the feces with only
a fraction of the product will be eliminated in the urineof normal animals.

Animal Preparation
and Other Considerations
You should consider implementing the following recommendations for preparing and anesthetizing animals tohelp optimize your imaging studies. All studies should bepreceded by a preliminary investigation to validate experimental parameters. You should note that animal strain,diet, housing, dosage, experiment design, and other factors may affect the metabolism of Fenestra®.
Always follow your approved experiment protocol andthe accepted standards for the care and use of laboratory animals whenever you prepare, anesthetize, ordose an animal.

Minimize Stress
Laboratory animals, particularly mice, are easily stressed
if they are not accustomed to being handled. Shieldingrodents from extremes of light, temperature variations,and loud noises can also make a noticeable difference in
how well experimental procedures are tolerated. Some
investigators opt for administering a short-acting inhalantanesthetic, such as isoflurane, to reduce or eliminate anxiety
associated with handling and dose administration.

Diet and Fasting
Most commercial laboratory animal chow contains considerable quantities of radio-opaque minerals that can causesignificant image artifacts. If possible, fast animals prior toimaging studies or, preferably, place animals on a liquid orsoft vegetable diet 24 to 48 hours prior to imaging.

Benadryl Pretreatment
Some users report that pretreatment with Benadryl,
diphenhydramine hydrochloride, improves tolerance toFenestra®; presumably similar to the way Benadryl
can reduce the symptoms of iodine allergy in humans
receiving iodinated contrast media. MediLumine cannot
recommend a specific pretreatment procedure, but theliterature suggests that mice can tolerate Benadryl up
to at least 10 mg/kg body weight delivered via intraperitoneal injection.

Hydration
Evidence suggests that mice tolerate Fenestra® better
when they are well-hydrated. This is not surprising as
most protocols involve large doses of agent relative tototal blood volume and Fenestra® agents comprise over
20 percent lipids by weight. Achieving optimum hydration
includes allowing unlimited access to water up to theinitiation of anesthesia and as soon as animals return toconsciousness. As an alternative, some users inject a 0.2
to 0.5 ml isotonic saline solution subcutaneously between
the shoulder blades shortly before IV administration ofFenestra®. Other users habitually administer liposyn intraperitoneally prior to administration of Fenestra®.

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Keep Animals Warm

Cardiac and Respiratory Gating

It is vital that the animal’s body temperature is maintained
within acceptable limits at all times. Careful use of a mildheat source, such as a heating pad or heat lamp, during
animal preparation and waiting periods can help prevent
hypothermia. Control of body temperature is especially
important while animals are anesthetized and during recovery. Wrapping the anesthetized mouse in a single layerof bubble wrap can help maintain body heat during thescanning regimen.

Gating may be necessary for some cardiothoracic imaging studies if normal respiration affects image quality.
Refer to the review article Gating in small-animal cardiothoracic CT (Methods. 2010 Jan;50(1):42-9. doi: 10.1016/j.
ymeth.2009.07.006. Epub 2009 Aug 3 available atwww.ncbi.nlm.nih.gov/pubmed/19651213).

Anesthesia
The choice of an anesthetic or other agent for immobilization should always be based upon individual protocols
and local guidelines. When determining your anesthetic
needs, you should consider the duration of anesthesiarequired for completion of the scan, the desired level ofanesthesia, and how anesthetic affects on respiration
rate and cardiac function may influence image quality.
You should also be aware that some anesthetic agents,
such as pentobarbital, may alter the pharmacokinetics ofFenestra®. Consult a veterinarian and your local guidelines
when considering the use of any agent.
Isoflurane inhalation is a preferred approach for anesthesia,
as it allows animals to recover quickly and is amenable tomultiple same-day scanning sessions. A typical procedure
calls for inducing mice at 4 to 5% and then maintaining anesthesia at 1.5 to 2% isoflurane. The animals should be fully
anesthetized and ready for injection and scanning within afew minutes. As an alternative, some researchers use an
intraperitoneal injection of a mixture of ketamine (80 mg/kg
body weight) and xylazine (5 mg/kg body weight). This technique usually affords 45 to 60 minutes of anesthesia.
Maintenance of anesthesia can be achieved with quarter
dose increments as needed.
You should note that when animals are to be scanned at
multiple time points on the same day, it is usually preferable to bring them back to consciousness between scanning procedures. You should also note that animals are
particularly prone to hypothermia when anesthetized andshould be kept warm until they can resume normal activity.

8Injection Techniques
Fenestra® is typically administered intravenously via thelateral tail vein, but can be introduced into any viablevessel. The use of a catheter, such as Strategic Applications’ 12-inch mouse tail vein catheter MTV-01, is strongly
recommended. Terumo tuberculin syringes can also beused. Because Fenestra® persists in the animal for several hours, rapid injection is not required. A slow bolus
injection rate of about 1 ml/minute is optimal. If injected
properly, the agent should flow smoothly into the vessel
with virtually no resistance. Do NOT inject Fenestra® unless you are sure that the catheter or needle is in the vein.
You should note that tail vein injection requires considerable skill. Ask for assistance if your own experience islimited. Successful tail vein injections can be facilitatedby dipping the tail in warm water to induce vasodilation,cleaning hair and scales off the tail at the injection site,using a magnifying light to properly visualize the vessel,
and inserting the needle with the bevel facing up and thenrotating once inside the vessel.

Troubleshooting
Why didn’t I get good
vascular contrast?

Why are there so many
image artifacts?

Contrast enhancement can vary for a number of reasons.
The most common source of poor contrast is completeor partial extravasation of the dose during injection. If in
doubt, scan the tail of the animal to determine if your injection was successful. If the tail is bright, the injection
was extravasated. For recommendations about administration, refer to Injection Techniques on page 8.

Inappropriate selection of anesthesia or inadequate anesthetic dosing can have a dramatic effect on image artifacts. Inhalation anesthesia normally results in the animal
having greater respiratory motion than if an injectableanesthetic, which can induce respiratory depression, isused. However, injectable anesthetics may introduce other
undesirable effects that range from periodic respiratory
gasping to altered metabolism and susceptibility to overdose
death. Conversely, inadequate anesthetic dosing may yieldsignificant motion artifacts.

When should I be imaging?
When using Fenestra® VC in mice, optimal contrast enhancement in the blood is provided for up to four hours afterinjection. When using Fenestra® LC, optimal liver contrast
enhancement is provided at approximately four hours
after administration, but earlier and later time points canalso provide adequate contrast enhancement. For otherspecies, optimal timing may be different.
You should note that optimal timing can vary wheneverhepatic function is altered, for example during diseaseprogression and treatment, in alcohol studies, with theintroduction of special diets, or if transgenic mice are used.

You should note that cardiac and respiratory gating canincrease the resolution of the thoracic region, as indicatedin the topic Cardiac and Respiratory Gating on page 8.
Contents in the gastrointestinal tract can also introduce
significant artifacts. Refer to the topic Diet and Fastingon page 7 for information about animal preparation priorto scanning.

How can I get additional help?
For more information about applications, experimental
design, or for any other technical question, you cancontact technical support for Fenestra®
Technical support
MediLumine Inc.
5795 Av. de Gaspé, Suite #112, Montreal, QC, Canada, H2S 2X3
Tel: 1.844.360.1574
Email: techsupport@medilumine.com

DISCLAIMER: Your results may vary depending on the scanner model and settings, animal strain and sex,
injection technique, the specific animal models employed, and other factors. Use of the tips described in thisdocument cannot guarantee success. Some or all of these suggestions may be ineffective or even harmful
depending on circumstances. MediLumine has not verified the suggestions contained herein and assumes
no liability with respect to their use. Users accept all risks and responsibility for losses, damages, costs, andall other consequences arising directly or indirectly from use of this information.
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