Scanning for Alzheimer's Disease

I recently had the opportunity observe a PET scan for Alzheimer's Disease.  This scan makes use of a recently FDA approved radioactive diagnostic agent, known as Amyvid (or Florbetapir F 18), to scan the brain for beta-amyloid plaques that are present in brains afflicted with Alzheimer's disease.  I thought that I would blog about this specific scan because it is relatively rare - although FDA approved Medicare does not cover the scan.

Beta-amyloid (Abeta) is the result of enzymes cutting amyloid precursor protein (APP.)  APP's function is not yet completely known, but it is known that APP freely passes through the fatty membrane of brain cells.  APP is typically cut into smaller segments that are designed to stay either inside or outside of brain cells.  There are many variations in the way that APP is cut, and one of the variations is Abeta.  A single Abeta molecule is relatively harmless and highly soluble, but Abeta is "sticky" and will stick to other Abeta molecules to form  oligomers.  Oligomers can exist in several different forms, however a misfolded one is believed to induce the misfolding of other oligomers.  Abeta in general is highly attracted to the synapses of brain cells, and once oligomers of Abeta progress into beta-amyloid plaque, the plaque is no longer soluble, will block synapses and eventually kill brain cells.

Amyvid was recently approved to aid in the diagnosis of Alzheimer's disease.  There are several tests that can indicate Alzheimer's disease, but none of them can fully diagnose Alzheimer's since Alzheimer's is best diagnosed postmortem.

The idea of a Florbetapir F 18 injection is that it will bind to only to beta-amyloid plaque and a PET scan can determine if the Florbetapir F 18 binded to the beta-amyloid plaque or not.  A positive scan will indicate that there are beta-amyloid plaque levels similar to those afflicted with Alzheimer's and Florbetapir F 18 binded to the beta-amyloid plaque, while a  negative scan will indicate that there is no or minimal levels of beta-amyloid plaque present in the brain and Florbetapir F 18 did not bind to the beta-amyloid plaque.

Amyvid has not been approved for the diagnosis of other cognitive disorders and alone does not diagnose Alzheimer's, although studies have shown Amyvid to have high sensitivity and specificity.

"Florbetapir gives patients with cognitive decline, their families and the physicians who treat them, more information about the amyloid plaques that may be found in their brain." - R. Edward Coleman, M.D., professor of radiology, Duke University Medical Center.

Nuclear ("Unclear") Medicine

Hi everyone!  I am currently in one of the most obscure fields of radiology known as nuclear medicine.  The goal of nuclear medicine is to treat and diagnose diseases based on cellular function and physiology, as opposed to waiting for changes in the physical features of tissue to diagnose conditions.  This is advantageous because potentially life threatening conditions can be identified in very early stages.

The main tools that nuclear medicine uses are radiopharmaceuticals.  Radiopharmaceuticals are formed from chemically bonding radionuclides (which are essentially radioactive materials) and pharmaceutical compounds.  Once formed, radiopharmaceudicals (which typically emit gamma radiation) target specific tissues in the body and then images of the target tissues are captured using a gamma camera in a form of diagnostic imaging known as scintigraphy.  A gamma camera can be thought of as a much more sophisticated pinhole camera, because the captured images are essentially pixelated by gamma of radiation.  The reason that gamma radiation is used instead of alpha or beta radiation is that gamma radiation has a much larger frequency and will penetrate through tissue much more easily, thus creating a better image.

Ventilation/Perfusion Scan

The above image is a ventilation/perfusion scan and is an example of why nuclear medicine is oftenly referred to as "unclear" medicine.  Every image in nuclear medicine looks this unclear, however it is at least obvious that these are lungs.  Despite how old fashioned this image looks, it can be used by a nuclear radiologist to check for a pulmonary embolism - a condition that can be fatal if untreated.

Bone Scintigraphy 

The above image is a bone scintigraphy/scan.  The scan has the same underlying idea as the other scans in nuclear medicine, except the pharmaceutical that is bonded to the radionuclide (typically technetium-99m) targets the bones.  This scan checks for bone abnormalities.  The idea is that the parts of the bones that are more active will have a higher amount of blood flow and absorb more of the radiopharmaceutical and show up as "dark spots" on the scan.  The dark spots can simply be from fractured bones trying to heal themselves, but they could also be from cancers on the bone.  For example, prostate cancer tends to spread to the spine and breast cancer tends to spread to the ribs.  I am no doctor, but this guy looks like he is in bad shape. An important detail to note here is that nuclear medicine does not diagnose what type of cancer a person has, but rather that there could be cancer.  For example, some people have naturally occurring symmetrical dark spots on bone scans that are not cancerous.

CT-PET Image

Another powerful tool available to nuclear radiologists is a PET-CT Scanner.  A lone CT or PET scan may be difficult to read and a doctor may overlook a small detail, but together a CT-PET scan is truly a guide to the human body.  The PET scan uses radioactive glucose to measure metabolic activity (the idea being that overactive and possibly cancerous cells will be metabolically over active) of tissues in the body, while the CT scan acts a map to determine where exactly a possibly cancerous tumor may be.  It is important to note that once again, nuclear medicine does not determine if a growth is truly cancerous, but rather that something could be cancerous.  For example, a PET scan simply measures metabolic activity through the use of radioactive glucose.  These tissues that are metabolically overactive will show up as brighter and as a "hot spot" on a PET scan, however something that is a "hot spot" on the PET-CT scan could be due to an injury or overactive lymph node as easily as it could be cancerous.  The ability to distinguish between "suspicious" and "non-suspicious" hot spots on PET-CT scans comes form both an expensive knowledge of physiology and experience - which is one reason why experienced attending Nuclear Radiologists make "the big bucks."   Last week, there was a patient that had a history of fungal infections and the attending nuclear radiologist was unable to determine if a nodule in the lungs was due to an infection or cancer.

The above images are PET-CT scans of the lungs, and both scans display a pulmonary nodule as a very bright hot spot.

My Week in Interventional Radiology

Hi eveyone! I hope your internships are all going well and I thought I would let you all know what I was up to in the first week of my internship.  I am now in another specialized field of radiology called nuclear medicine, however last week I was shadowing a group of radiologists that specialize in something called interventional radiology.

The whole goal of interventional radiology (IR) is to perform image-guided minimally invasive procedures on patients to both treat and diagnose conditions in nearly every organ of the body (so the IR department regularly coordinates with almost every division in the hospital).  In most procedures, an interventional radiologist will gain access to a patient's circulatory system via the femoral artery by using an ultrasound device to find insert a catheter (small tube) into the artery.  Once in the femoral artery, the radiologist will use a medical-grade wire guided by images from a machine called a "C Arm" to gain access to any part of the body.  A C Arm produces continuous real time images of the wire going through the arteries.  Since x-rays are used during these procedures, everyone in the operating room is required to wear lead vests and dosimeters (badges that measure cumulative exposure to radiation) at ALL times.  Once the wire is in place, a microcatheter (very small tube) is put over the wire and inserted into the body.  Using the mircocatheter, intravenous fluoroscopy (which uses contrast agents to highlight parts of the images) can be performed to highlight arteries on the x-ray.

Swallowing Contrast Agent (A form of Fluoroscopy)

C Arm 

The benefits of interventional radiology are evident in the procedures themselves.  During my time in the department, general anesthetics were rarely used in any procedure.  The incision is so minuscule and the procedures are so noninvasive that the patients are conscious for almost every part of the procedure (unless the sedatives force the patients to sleep.)  One patient was completely lucid and even had a full conversation with the attending doctor and resident during a procedure.  After procedures are over, almost every patient (the IR department works with "in" patients as well) leaves the hospital the very same day.

Despite how harmless these procedures may seem, they are extremely effective and are even preferential to traditional surgery in some cases.  Interventional radiology is not a preferential treatment plan for patients that are in need of immediate care (i.e. unstable trauma victims), but is preferential for patients that are stable or bad candidates for surgery (i.e. patients that are older or have lost a lot of blood.)

During my time in IR, the most popular procedure was a port-a-catheter.  The point of this procedure is to insert a port (which can be injected with medicine) under the skin and attach the port to a catheter that feeds into the end of the superior vena cava and directly into the heart.  This procedure is for patients that are going to be regularly receiving medicine in quantities that veins could not handle (i.e. chemotherapy.)  The heart is much stronger than the veins, so the heart can receive much stronger medication, as well as effectively distribute the medication to all parts of the body.

Port-a-Catheter

A port-a-catheter is one of the most common procedures during the day, however it is not the only one that can be performed.  Patients with internal bleeding, restricted blood flow, or at risk of an aneurysm  may have a stent placed.  A stent is essentially a mesh tube that is placed into a vein or artery to reopen it and restore normal blood flow.  In addition to placing a stent, IR doctors may embolize certain parts of the body.  Embolisms are the opposite of stents in that they completely block blood flow in arteries and kill the tissue that it blocks blood flow to.  Patients may have arteries to a cancerous cyst embolized, as well as if an organ is uncontrollably bleeding or about to be removed.

The most memorable procedure I observed during my time in IR was on a patient that had been the victim of a trauma and was brought to interventional radiology by the trauma unit.  The trauma unit had stabilized all of the patients injuries besides one - the patient's spleen was bleeding.  The patient had already lost a substantial amount of blood and was not a good candidate for the surgical unit to remove the patient's bleeding spleen to stabilize the patient.  The patient was brought to the IR operating room while still receiving a blood transfusion to keep the patient's blood pressure stable.  The trauma surgeons were observing the procedure in hopes that the bleeding was not extensive and repairable.  In order to determine how badly the spleen was bleeding, the IR doctors performed an angiogram of the spleen to find the origin of the bleeding, as well as the extent of the damage to the patient's spleen.  Fortunately, the spleen did not need to be embolized to stop the bleeding.  Instead, the IR doctors were able to use a type of foam that clots around damaged areas and stops bleeding.  So in the end, the IR doctors saved the patient's spleen and the patient did not have to undergo open surgery to remove the spleen. 

The week in IR kept me on my toes and I learned a lot.  Interventional radiology gave me the opportunity to gather valuable information, as well as opened my eyes to many different types of medicine that I never knew were possible.  Interventional radiology is a powerful tool that is constantly developing and refining treatments to effectively treat conditions with less of a risk to patients.

If I had a choice between surgery and IR, I would definitely choose IR.

Pre-First Day

Hello and Welcome to my Blog!  My name is Cordero Ortiz and I am a BASIS Tucson North Senior.  As part of my senior year at BASIS, I have opted to participate in an individual research project.  After a lot of thought, I have decided to research treatment methodologies implemented by radiology.

I was EXTREMELY lucky to be offered an internship in The University of Arizona Medical Center's Radiology department.  My internship will start on Monday and I am to shadow a doctor that specializes in interventional radiology for a week, a doctor that specializes in nuclear medicine for two weeks, and a doctor that specializes in pediatric radiology for three weeks.  

Before beginning this internship, I had to sign a confidentiality agreement with the hospital, as well as complete Health Insurance Portability and Accountability Act (HIPAA) training.  HIPAA reduces healthcare fraud, streamlines the healthcare industry, guarantees that health insurance will transfer between jobs, and provides strict guidelines for the handling of patients' private health information.  HIPAA regulations are very important and violations of the act are taken very seriously.

After my training was completed, I visited the hospital on Friday for my orientation.  I was given a tour of the maze (the lobby is apparently the second floor), I met all of the doctors besides one that was in surgery, and I went to visit the Office of Radiation, Chemical and Biological Safety (ORCBS) to get a dosimeter badge.  This badge will measure the cumulative radiation that I am exposed to during the duration of my internship.  It is just a precaution implemented by ORCBS, which regulates the entire hospital to ensure everyone's safety.

The facility was truly top notch and the doctors, residents, and fellows were all extremely professional, but very friendly.  The whole experience was very surreal because it was a glimpse into a future that I am interested in.  Everything seemed up beat and complex, but very interesting.  I was admittedly intimidated at some points of the tour, but the intimidation just made me interested in learning more.

I am nervously excited to start tomorrow.  Wish me luck!