Medical imaging of cerebral lesions

AVM's are considered in the medical world as abnormal lesions forming in either the brain or any other parts of the human body along as there are endovascular networks that are present, primarily the  arteries and veins. Knowing this, it makes it absolutely essential that the right kind of medical imaging is applied to identify the location of such lesions and it's size to determine its possible treatment outcomes. A lot of you AVM patients out there are familiar with the kind of medical imaging that is available out there to achieve this but it's also important to be mindful of the capacities and limitations of each medical imaging types. The most common being digital subtraction angiography, magnetic resonance angiography and computerized tomogram angiography. Each type of imaging are all effective in identifying the presence of AVM's or any other form lesions but they all can only be applied during the right circumstances.

1. Digital subtraction angiography: This method has always been the gold standard for doctors in identifying AVM's mostly because this type of angiogram uses a catheter that's able to reach deep inside the cerebral interior via injection through the femoral artery, the largest artery in the human body. The advantage of this medical imaging is that it's capable of identifying lesions up to a size of 7mm or less. This form of medical imaging will come in handy for AVM patients after they have done treatment to remove their AVM's either through craniotomy, embolizations or radio therapy. The only downside of this method is that it uses a catheter with micro camera that would have to be injected through your arteries, the blood vessel that carries blood from the heart through all parts of the body. So it's no surprise that there will be a lot of bleeding, when the injection takes place. Though the thought of doing this kind of angiogram is scary, it is still relatively safe and with less complications. After doing the procedure, it is essential that pressure is applied on the area bleeding for about six hours to stop the blood circulation from flowing. When applying pressure, it also necessary to stay still as well to limit blood circulation to that area.
2. Magnetic resonance angiography: This form of angiogram is done with the help of an MRI machine, the fluid used for the imaging will be similar with the one used with the standard digital subtraction angiogram, the only difference is that it reacts with the magnets to give a contrast image of the endovascular formations. The plus side of this method is that it's less invasive and there is less complications when doing the procedure. However, this imaging may have complications for patients with metal implants in their body so it's advised that doctors are informed first of any potential foreign objects that may be present before conducting the scan so that an alternative scan can be given that doesn't involve the use of magnets that may endanger patients. the angiogram fluid that will be used for the scan could also pose a risk for patients especially if they have allergies to certain substances. it should be noted that though some allergies are not present in the substance used for the angiography such as seafood allergies, the basic element that's present in such allergies may still be present in the fluid used for the angiogram, in this case it would be iodine. If patients are aware that they have allergies for seafood then they should inform doctors not to use any angiography with iodine in it. 
3. Computerized Tomogram Angiography (CTA): Similar with an MRA, both are a form of angiography the only big difference is the imaging. A CTA uses X-rays to capture internal images of the human body. The benefits of an X-ray assisted angiogram is that it provides a clear 3D picture of the endovascular structure which may help in detecting aneurisms. This is also the gold standard of medical imaging that is often used for the preparation of radiation treatment; Gamma knife, cyberknife and proton therapy. All of these fall under the sub type of radiation treatment that require the use of a CTA to determine the exact location of the AVM so that it can be targeted with precision.

Though the description of each type of medical imaging mentioned above is straightforward, certain cases may require a combination of one or more medical imaging especially when it comes towards deciding a treatment option. for example in the case of preparations for radiation treatments, it is common that 2 CT scans will be conducted on separate occasions for different purposes. One scan will be conducted to identify the size and location of the AVM's including the number of arterial feeders that are present. The other scan will be done to plan out how the radiation will be implemented to treat the area with lesions. However if patients are worried of the thought of using ionizing radiation for medical imaging because of the risk of DNA damage from radiation, it can be changed upon request that patients get an MRI instead of a CT scan for the imaging, however it's most likely that it's non negotiable to have different type of imaging before the treatment takes place. That being said, you can be rest assured that ionizing radiation in medical imaging such as CT scans are still safe both before and after the treatment, as the ionizing radiation used is substantially low.