The interesting, the weird and the technical world of Nuclear Medicine, geared towards students. It's a blog for students who are in their clinical practicum .... or for those who are just curious.
Fig. 1 Patient presents with multiple rib fractures as well as a fracture of the sternum
So what's wrong with this picture? There are several things as you can note with multiple rib fractures and a sternal fracture as well. Originally the patient was to have scans on the hands and wrist as indicated on the requisition. A total body scan was performed with locals of the hands and wrist. The locals were unremarkable, but the chest and ribs are very remarkable.
Some clues for you. No recent thoracic surgery or recent motor vehicle accident. The patient walked into the department with no deficits. However, and this might give it away, he did recently have a heart attack.
If you have guessed it, this person was a recipient of CPR administration a month earlier after he had a heart attack. The delivery of chest compressions from the CPR contributed to the current presentation. If this was me, forget the CPR, just use the AED's and zap away!
Click here for another example that I found online in regards to bone scans and CPR.
Just got back from Chicago... (fun town), on a training seminar in regards to TheraSpheres. For those in the United States and Europe, this might be routine practise in treating liver cancers (hepatocellular carcinoma HCC), but not so much here in Canada. There are only a few places in Canada that are performing these procedures (BC, Alberta) but not sure what type of volumes they have in regards to this type of treatment. The Nordion sales reps have stated that they have some type of involvement within these regions.
At any rate what is a TheraSphere? They are glass beads with Yittrium-90 attached to the surface. The beads themselves are biocompatible and insoluble and have a mean size between 20 - 30um. These beads are injected through a femoral line while undergoing a hepatic angiogram in Interventional Radiology (IR) and the beads are deposited close to the site of the liver lesion that you want to treat.
What's tricky about this is, figuring out the blood supply to the region of the liver in and around the tumour site(s). For the most part the blood flow to the liver is fairly predictable, but with respect to some patients it's a bit more complicated because of a variety of arterial variants, parasitization of flow, accessory arteries, retrograde blood flow etc. that if not found with a thorough investigation, the deposition of the TheraSpheres will not go entirely to the tumour, but elsewhere within the body. This is not a good thing, since adverse reactions may potentially occur. The case studies illustrated these quite well at the training seminar. However, for the most part Yittrium-90 radioembolization of the HCC tumours has several advantages in that it has a lower toxicity profile in comparison to transarterial chemoembolization.
So what does TheraSpheres have to do with Nuclear Medicine? Well for the most part we assay and deliver the Yittrium-90 to the angiography suite, and from there the IR techs and the IR doctors take care of the rest with respect to the injection and the clean up. This will vary from site to site, depending upon the level of comfort and training in dealing with radioactive materials.
However even before this occurs, Nuclear Medicine is important in determining extra hepatic shunting to the lungs or gastrointestinal tract as part of the selection process in figuring out who are good candidates for this treatment.
150MBq of Tc-99m MAA is injected with a microcatheter into the hepatic artery after coil embolization of all visible non hepatic arterial flow. Basically, whatever blood flow that doesn't deal with the liver, they get clamped down with coils, in order to figure extrahepatic flow. The image below is an example of this type of imaging.
Fig. 1 ROI's drawn over the lungs and liver to determine the counts for geometric calculations to determine the Lung Shunt Function (LSF)
Anterior and posterior images are taken to determine regions of interest (ROI) to find out the Lung Shunt Fraction (LSF). The geometric means are calculated from the lungs and liver using the numbers from the ROI's and are used in this equation:
LSF = Lungs / (Liver + Lungs) *100
The reason why this is important is because it helps in determining the dosimetry calculations for pre and post treatment. This is important since you need to know how much radiation to give given a specific volume of liver that you plan to treat without affecting other parts of the body (ie. lungs).
There is the question of planar versus SPECT/CT imaging with MAA. At the training seminar, planar imaging was described, but others have suggested performing SPECT/CT. Since at our site we have limited experience with this protocol, we would need to speak to the IR doctors and the Nuc Med doctors to figure out what they want.
- 37 -185 MBq Tc-99m MAA, injected in IR and the patient delivered to Nuclear Medicine
Equipment:
- Any large FOV dual detector gamma camera, with LEAP or LEHR collimation
Imaging:
Option 1: The patient is positioned supine under the gamma camera and 4 images are acquired. Anterior and posterior images of the abdomen and of the thorax are acquired separately
Option 2: The patient is positioned supine under the gamma camera and a whole body scan is acquired
Camera Parameters:
- Acquisition matrix = 256 X 256
- Zoom = 1.45 or less to ensure all activity visible in FOV; total counts >1M
- Counting time - 5mins per 74 MBq administration of Tc-99m
- Dual headed gamma camera, with SPECT/CT capability
Imaging:
- 30 minutes post injection of Tc-99m MAA, anterior and posterior planar images of the whole body
- SPECT/CT afterwards
Camera Parameters:
- SPECT - 128 X 128 matrix
- 128 frames (25 secs/frame)
- CT - 130 keV, 17 mAs, 5mm slices
There is also talk about PET/CT imaging as well. Since Yittrium-90 is a beta emitter, having the patient come back the following day after treatment allows imaging of the distribution and deposition of the microspheres within the body.
Anyway, there is a lot to know about this procedure and I am only scratching the surface. At our facility we have had some experience with this many years ago, but now there is a real push with some of the doctors at the hospital to revisit this type of treatment again.
Stay tuned........
Update: Check out Theraspheres Part Deux, in this blog site. We've performed out first LSF and treatment.
Fig. 1 Post 72 hour whole body gallium imaging for a 74 year old patient, with B cell lymphoma
Gallium scans, in general, are fairly routine in helping clinicians to understand the extent of certain lymphomas in their patients. For the most part PET imaging is the standard of care in many parts of the world, but with limited access to this type of imaging in certain provinces, we still rely on gallium (ole faithful).
What is interesting about the image above is the location of the gallium avid tumours. I personally have never seen uptake in the actual arm itself. The images above describes the uptake in the right infraclavicular lymph nodes, right axillary lymph nodes, soft tissues lateral to the mid shaft of the humerus and soft tissues posterior/lateral to the distal shaft of the humerus. A SPECT/CT was performed, which included the arms and thorax. The sagittal slice reconstruction below helps in clarifying the location of the tumours in the arm.
Fig. 3 Sagittal reconstruction of the right arm localizing the gallium avid tumours. The video below is the 2-bed SPECT scan of the patient.
The patient initially presented with anemia. Upper and lower gastrointestinal investigations did not reveal anything out of the ordinary, but the blood work for hemoglobin, mean corpuscular volume (MCV) and ferritin results were abnormal. The lumps and nodules in the right arm have been present for 8 years, and it was only recently that they began to grow in size, but were not painful. The patient was diagnosed with diffuse B cell lymphoma and is currently undergoing treatment.
Sorry about the appearance of the image... I was not able to invert the colour scheme.
However, this patient presented to our department to determine if osteomyelitis was present in her right upper jaw. In short, our doctors were unable to decide if the site had osteomyelitis, because of other confounding circumstances such as the patient's recent dental work in the same area. It was tough because they were unsure if there was some type of odontogenic infection occurring as well. Plus the extent of the underlying bone that was involved in this infection was difficult to resolve given the patient's underlying bony lesions. The sulphur colloid (bone marrow images) and the delayed In-111 WBC images are not included for viewing because the interesting point about this case, is the actual total body bone scan itself.
McCune Albright Syndrome (polyostotic fibrous dysplasia) is a genetic disorder that affects the bones and pigmentation of the skin. It is not a common disorder and the exact number of cases in the United States and internationally is not known. However what is interesting are the multiple abnormal foci of increased activity noted within the bones, this in keeping with the nature of the syndrome. Anyway I thought this was more interesting than the osteomyelitis component of this case.
Fig. 1 Total body bone scan of a patient diagnosed with renal cell carcinoma.
As a technologist what would you do after the total body bone scan (TBBS) was complete? I think one of our main duties are to review the images to see if there are any asymmetrical bone uptake relating to the patient's history and to take extra pictures if needed. With respect to the images above, there are a few spots, in particular the spine, but other than that nothing too remarkable to talk about. Unless you take a closer look at the pelvis. Is this contamination or is this "something else"? Well it has to be something else or else it wouldn't be on this blog.
So, what are our options to figure out, what's going on in the pelvis?
a. Take a quick lateral view, to see if this is truly contamination
b. SPECT or SPECT/CT
c. Squat view on the camera (ie. have the patient sit on the camera) to separate bone versus soft tissue
Since we have a hybrid system, we SPECT/CT'ed the pelvis. So the question you are asking yourself right now is, why did we opt to do this? Well if you look at urine contamination on patients in general, it usually looks more "drawn out" - dribbling with smaller spots. Also in this TBBS the margins of the "spot" below the bladder proper, are smooth and well defined... so it doesn't really fit with our pre notion of what contamination would look like. Plus, we had the time and we needed the "billings" and the workload units, so we did it... I am joking of course (as someone pointed out) .... And this is what we got:
The SPECT is interesting. The "spot" is anterior to the bladder, but really not on the surface of the skin. Below is the CT transaxial slice of the pelvis from the SPECT/CT.
Fig. 2 Transaxial CT image of the pelvis from the SPECT/CT scan. Notice the "pear" shaped bladder.
Notice the bladder in the pelvis(click on link for normal looking bladder). It looks like a "pear" with the most anterior lobe shifted to the right extending beyond the pubic bone. Is this still contamination? Here's another look with the sagittal slices for SPECT, CT and fused SPECT/CT slices.
Fig. 3 Sagittal SPECT view of the pelvis. Notice the bladder and the anterior ovoid "spot".
Fig. 4 Sagittal CT slice of the pelvis. The bladder has a flaccid phallic appearance.
Fig. 5 Fused SPECT/CT sagittal slice. Everything is starting to make a little bit more sense.
Well if you haven't figured it out now, the "spot" that you actually see is the bladder. The bladder has herniated out and dropped below the pelvic floor... the patient has a herniated bladder! This is something that we normally do not see very often.
The indication for this patient was to have a metastatic work up, because they were re-diagnosed with renal cell carcinoma (RCC), this time in the right kidney. The bone scan was included in the work up for metastases in the bones. There were no clear cut evidence for this, but there were a lot of expressions of degeneration in the joints and notice one kidney is missing... the left one on the TBBS. The left kidney had been removed in 2009 as the result of RCC. Even though there were no bony evidence of metastases, the separate CT scans showed a large liver lesion indicating the progression of his disease from his right kidney (images not shown).
Okay here's one... regulations are not my strong point but since we have a Corporate Radiation Safety Office (CRSO), who gets on everyone's case, they generally have a good grasp on the regulations.
Q1.
1) Can you
clarify what exactly is the difference between thyroid monitoring, thyroid
screening and thyroid bioassay for nuclear medicine workers handling radioactive
iodine? I thought they were all pretty much the same thing but it seems like
the CNSC considers them three different things.
2) There are a few
different documents that have some conflicting information on them about how
much radioactive iodine a nuc med worker can be exposed to before they must
participate in thyroid screening program. I think that some of these documents
are older and that the rules have changed...I just wanted to make sure I am
learning the most up to date regulations for the exam: According to document
RD-52, you must participate in a thyroid screening program if you are exposed to
2MBq (benchtop), 200MBq (fumehood) or 20,000MBq (glove box) of volatile I-131 or
I-125 and your screening must take place within 1 to 5 days....is this correct?
According to another document INFO-0546 it said you must participate in thyroid
bioassay if you manipulate greater than 5MBq (benchtop), 50MBq (capsule form),
50MBq (fumehood) or 500MBq (glove box) of volatile I-131 or I-125 in a time
period of 3 months and your bioassay must take place within 1 week. Is
INFO-0546 still relevant?
A1. The response from CRSO:
1)Your best reference is CNSC RD-58 “thyroid
screening for radioiodine”. To sum it up: The term thyroid monitoring isn’t
really used anymore. Your two main terms are thyroid screening and thyroid
bioassay. The term “screening” refers to a routine program that can detect the
presence of iodine in the thyroid above or below certain threshold levels.
Essentially what you all do in Nuc Med on a routine basis. Thyroid bioassay is
done to quantify not just the presence but the resulting committed effective
dose, if one of the screening levels were exceeded. That calculation can only be
performed by somebody certified by the CNSC.
2)RD-58 has the current requirements and they
are the 2, 200, 20000 MBq and they were implemented this year. The 5, 50, 500
MBq are now old numbers.
