Week 7 NM and Interventional Neurology(INR)

This week I was partly in Nuclear Medicine (NM) department and partly in Interventional Neurology (INR) department.

In NM I was able to observe patients being imaged using Positron Emission Tomography (PET) scan.

In PET-scan, Fluorine, F18-FDG (fluorodeoxyglucose) was used as the radiotracer. Prior to PET imaging and radiotracer injection, a patient has to fast for at least 4 hours so that when F18-FDG is injected there won’t be any competition from glucose in the blood during glucose take up by active organs. Glucose measurement is usually taken from patient’s blood prior to injection of radiotracer, and a reading below 200mg/dl is acceptable for PET imaging, while a reading above 200mg/dl disqualifies a patient for a PET scan diagnosis.

Any abnormal tissue will take up a lot of glucose so this will make the isotope more flow into abnormal tissue, such as infections or tumors in organs like liver or kidneys. After injection and before imaging, the patient has to rest so that the glucose doesn't go to other organs that may be active if the patient is moving or active.

During PET-scan, a scout/planar image is taken first which is then used to position the area the technologist is planning to scan/image. Then a CT scan is taken, which will provide anatomic structure/roadmap during imaging analysis. Finally, a PET scan is taken. Since a PET scan image only shows the areas of concentration of the radiotracer in the body but doesn’t show the anatomic layout/body organs structure, PET images are overlaid/combined with CT images which will help the physician during analysis, to know which parts of affected organs have abnormal tissue.

Figure 1: A typical PET scan machine. (Source: http://www.medgadget.com/2012/02/siemens-biograph-mct-pet-ct-system-receives-fda-clearance.html)

In INR I shadowed doctors treating and evaluating patients who had Aneurysm in the brain. Aneurysm usually occurs where blood branches into two branches.As a result, turbulence may result which causes increased pressure ,leading to weakened blood vessel walls and eventually blood leaking into the brain. Aneurysm is treated by putting coils to block blood flow into the aneurysm and block blood leaking into the brain. Fluoroscopy provided visual aid to the doctors during the procedure. The procedure was carried out by inserting the catheter through the iliac artery (if I remember correctly) in the hip, past the heart, into the carotid artery and then into the internal carotid artery, then a coil was inserted and was used to fill up the aneurysm in the infected vessel past the internal carotid artery.

Figure 2: Typical aneurysm and treatment (Source: http://www.mayfieldclinic.com/PE-AneurUn.htm)

I was also able to shadow Brain AVM treatment by embolism. AVM (arteriovenous malformation) is when  arteries and veins get connected in the brain.