Week 2 - Stevenson T

This week I found out the importance of being able to use unexpected free time. With the INCREDIBLY busy schedules our mentors have, some meetings get postponed/cancelled, leaving you with several hours of unexpected free time in the hospital. With that in mind, early on this week I attended neurology rounds with James Lata. As I’m sure he has given a good description of this event, I’ll skip to the highlights.

Neurology Rounds - This is the first time I have been present during patient/physician interactions. I realized that health care providers must strike a careful balance when feeling empathy for their patients. On first glance I thought the attending physician and residents were being slightly callous, but with retrospection, I believe they were simply maintain a healthy psychological distance. This distancing may be of special importance in neurology, as roughly half of the cases we saw resulted in no intervention. “We can’t make the patient any better, so why subject him/her to a risky procedure that may severely reduce the quality of life?”

A more technical observation I made during rounds involved one elderly patient who had previously received a deep brain stimulator (DBS) for treatment of Parkinson’s Disease. While the technology/biology of the DBS is, for lack of a better word, cool, I took issue with some of the engineering that resulted in the patients re-hospitalization. The patient returned to the hospital after complications during a procedure to replace the battery on the DBS. This outcome seems completely unjustifiable with today’s current electronics technologya. Why would someone design a device that could only be accessed through very invasive surgery to have a “short” battery life? We can already walk into Best Buy and purchase a wireless power transducer that is capable of charging mobile devices, so why couldn’t we use a similar device to recharge the batteries of this DBS….

Citigroup Biological Imaging Center (CBIC)- Located on 72^nd street, the CBIC is where my mentor, Dr. Joseph Osborne, performs the majority of his clinical research. Though I had been to this building on several other occasions, I didn’t have the opportunity to speak with any of the technicians or observe any actual scanning procedures. This week I was able to see several.

microPET – on Tuesday, Dr. Osborne’s team was imaging a Rhesus monkey using a microPET scanning device. More specifically, they were measuring the binding/displacement of [¹¹C]-raclopride /dopamine. By getting a quantitative measure of the fraction of radiation in the animal’s brain, it is possible to determine the amount of raclopride vs. dopamine bound to D₂ dopamine receptors. This study was a preliminary control experiment that will be used to help study the effects of cocaine on the brain.

CT-PET – This scan was performed for a clinical trial of the Pittsburgh B compound, an amyloid plaque binding dye that can be modified to contain ¹¹C for PET scanning. What I found most interesting about this procedure was the need for an accurate X-ray CT prior to the PET scan. When PET photons travel through tissue, they get deflected/absorbed or otherwise attenuated by a factor that is roughly proportional to the density of the tissue. Thus one is able to generate a relatively low resolution CT scan of the body so that when the PET scan is taken, one is able to correct for attenuation on a voxel by voxel basis. The problem with this is that the scan/detector equipment for PET and CT are incompatible, requiring two scan zones to exist in the machine. After the patient receives a CT scan in the first region, the robotic table moves the patient into the PET scanning region. Though I’m sure the robotic mechanism for moving the patient is well calibrated, I wonder if it wouldn’t be simpler to redesign the electronics to have both sensors in the same scan area.

MRI – Before this week I never really considered an MRI machine to be a safety hazard. Sure, the magnetic field is quite strong and can be dangerous if you’re not aware of it, but you can plan for that and keep lots and lots of signs up warning people. What I’ve never before considered is the explosive force of the liquid cooling agents that are used to bring the machine down to superconducting temperatures. These liquids are usually N₂ and He (-80*C and -265*C respectively) and tent to expand approximately 700 times in volume when they become gases. Release of these gases would be more than enough to blow out the glass windows of a viewing room and displace a large portion of the oxygen in the air. This safety concern coupled with the need to constantly keep the machines on left me with a healthy respect for their destructive potential.

Project – I’m unfortunately still not entirely sure what my role in the project is going to be. I might be making the radiotracers in the hotlab or I may be reviewed patient data in an attempt to locate possible candidates. Either way, I will be working on a project to develop a small molecule PET tracer [¹⁸F] labeled, that will bind to PSMA and hopefully reveal any metastases that have escaped the prostate. Eventually this type of molecular imaging may be used for diagnostics or treatment, but currently, our goal is to better track the course of the disease.