Transcript
MIC CAVAZZINI: Welcome to Pomegranate Health. I’m Mic Cavazzini, and I’ve just gotten off my e-bike at the Prince of Wales Hospital on Bidjigal and Gadigal lands in Sydney. It’s been a long time since I’ve actually recorded an interview in person, and today’s story is going to be very different from anything I’ve done before. I’ve been invited by a registrar in nuclear medicine, Dr Karan Singh, to shadow him for the day and share with you some of the interesting medicine and collaboration he gets to participate in. And I can see him standing over there waiting for me.
KARAN SINGH: I thought it'd be the person that's got a lot of stuff in their hand.
MIC CAVAZZINI: You’ve got the weapon already on you. Good morning. Thanks for having me.
KARAN SINGH: How are you?
MIC CAVAZZINI: Great. I’m looking forward to this.
KARAN SINGH: Thanks for making all this happen.
MIC CAVAZZINI: It’s going to be good. You’re looking remarkably refreshed after—is it six weeks the baby girl?
KARAN SINGH: Seven weeks.
MIC CAVAZZINI: Dr Singh is a new father and he’s adapting to this role as he completes his second last year of advanced training. Karan is actually the co-chair for the Trainee Interest Committee of the Australasian Association of Nuclear Medicine Specialists. He reached out with this podcast idea because he felt that the speciality wasn’t well appreciated by trainees as they make their career choices. So, one Monday in August, I joined him to record this teaser for you.
KARAN SINGH: Nuclear Medicine is a relatively small specialty, and I think there's probably not a lot of exposure to medical students, junior medical officers, the undifferentiated registrars. A lot of people have a misconception that nuclear medicine specialists are radiologists, and some and a lot of them are. But certainly, you can also access the training pathway through the RACP is an advanced training specialty, and I guess the purpose of me reaching out was to try to increase awareness as to what a nuclear medicine registrar might do, because you often won't see us unless you come to these multidisciplinary team meetings.
MIC CAVAZZINI: I think you said also that it's not a typical rotation..?
KARAN SINGH: Correct. Interestingly, there's been a lot of work done behind the scenes advocating for nuclear medicine to be a core rotation during basic training, and so that's been approved. I'm not sure as of today, how many trainees get the opportunity to spend time in nuclear medicine.
MIC CAVAZZINI: You told me that you actually started down the paediatrics training pathway. How did you fall into this then?
KARAN SINGH: So, I did my basic training and some of my advanced training through the paediatrics route, and then during that time spent a little bit more time reflecting on the things and tasks that I enjoyed at work. And that ultimately came down to things like; I really enjoyed working through complex cases with colleagues. You know, the highlights of my day would often be when we were sitting having coffee, discussing complex diagnostic cases. And so, I really enjoyed that cerebral side of things, but at same time, found myself getting quite emotionally fatigued with the lengthy and often complex patient interactions with patients and families. And so at the time, I did a lot of thinking and spoke to a lot of people and worked through, I think, almost every medical subspecialty I could. And during that time, I visited the Department of Nuclear Medicine at the Children's Hospital of Westmead, and I walked in, and everyone just seemed so friendly and happy with their lives.
MIC CAVAZZINI: And relaxed.
KARAN SINGH: And relaxed. Of course, that's not to say they're not working hard. But that was the hook for me to then go in and do my own research. I spent some time shadowing in the department, I went to one of their nuclear medicine conferences that year. And I was just fascinated by what kind of workday you can have in nuclear medicine. And that was really the hook for me to then apply for nuclear medicine training.
MIC CAVAZZINI: Dr Singh introduces me to the four consultants in his department. The Department Head, and also Director of the AANMS is Dr Eva Wegner.
EVA WEGNER: Nice to meet you. Part of the registrar’s work is that he gets constantly interrupted.
MIC CAVAZZINI: We drop in on Associate Professor Monica Rossleigh.
KARAN SINGH: She’s got so much knowledge. She’s the queen of renal nuclear medicine. Worldwide.
MIC CAVAZZINI: At the morning team huddle we meet Associate Professor Ivan Ho Shon who has interests in oncology and the quantifitation of PET signals. And Dr Walter Haindl who leans towards endocrinology applications.
Also at the meeting are a handful of nurses, a technologist for each of the five scanners in the department and a resident. Nurse Practitioner, Karen holds court, and runs through a list of over a dozen scans scheduled for the day.
KAREN: Welcome to Monday, everyone. According to the board, I'll just read it through very quickly, we've got the two MIBIs, two gastric emptying, two gated pool scans, one I-131, one amyloid bone, one straight bone, one next day lympho which is a breast. And then we've got, as I said, the 11 PETs.
MIC CAVAZZINI: Once the meeting is over, Dr Singh assists with some patient intakes. With the help of a resident, he educates them about the potential risks of nuclear imaging to ensure their consent. He’ll also ask about the patient’s history as there may be factors that can confound interpretation of a scan. Or if the referral contains nothing more than a two-word request, he’ll probe for more information that can help tweak the protocols to maximise sensitivity.
The radiotracers are administered in a lead-lined room to contain the radiation that they emit in the form of photons or gamma rays. These emissions are in the next smallest frequency range below x-rays, and there are two different ways in which they are captured for imaging. The workhorses of the department are gamma cameras, and these detect photons emitted directly from the decay of a given radioisotope, usually Technetium 99m.
As long as you’re able to pair this to a relevant bioactive ligand, you can image processes in any tissue of interest. Traditional gamma imagining, or scintigraphy, is planar and on many machines can be captured as a full body scan. Later we’ll get into the advantages of the 3D version of this, called single photon emission computed tomography, or SPECT.
This isn’t to be confused with PET, the other main modality in the nuke med toolkit. Here, the particular radiotracers used emit positrons, and it’s only after subatomic collisions in the tissue that gamma rays are generated. While PET technology originally progressed within the domain of translational neurology and cardiology, in the last few decades its use has surged across a range of specialties.
KARAN SINGH: As more is invested into PET, now most departments are split, 50:50. And even though it's mostly oncology now, there's a huge focus on infection and inflammation; a huge focus on dementia imaging and big focus on cardiology as well.
And so, I guess that brings me back to the crux of nuclear medicine in its differences from radiology is that we’re focussed heavily on what we call emission-based imaging. So, the more conventional imaging techniques like CT and X ray and ultrasound, will often use an energy source external to the patient, directed at the patient, and they'll be either a detector on the same side or a different side of the patient that picks up on that signal, whereas in nuclear medicine, we're injecting the radio trace or ingesting it or inhaling it. And radiation comes from inside out.
That's kind of the crux of the differences. I always tell patient—because I always have a pen on me—and I always tell patients, a CT or X ray or ultrasound will often be able to tell you the shape of the pen, the size of the pen, but they won't tell you if the pen works. Whereas nuclear medicine will provide a better assessment of how the pen works. How it feels. How it writes. Whether it's got ink in it.
MIC CAVAZZINI: That might be the hook to the story.
OVERHEAD: Dr Singh, could you please come to scanning room four, please Dr Singh.
KARAN SINGH: On the overhead, that's how we get paged in the department. So, we don’t have pagers, because I’m not roaming right around the hospital. I'm very localised to this department.
MIC CAVAZZINI: Yeah, you don't have to go very far.
MIC CAVAZZINI: Every 20 minutes or so, Karan gets paged to attend one of the imaging suites. We join technician, Amanda, in one of the dark control rooms, looking at the chest scans of an 80 year old man we’ll call Eduardo. The patient has a history of coronary artery disease and his cardiologist has referred him for myocardial perfusion imaging.
Among the team this gets called a MIBI, after the tracer, methoxyisobutyl isonitrile. The MIBI molecule is lipophilic and cationic, so it sticks to the plasma membrane and then diffuses into the more negatively charged mitochondria. Because myocardial cells have a high concentration of these organelles they should remain brightly labelled once the tracer has washed out of the circulation. Uneven distribution of the signal under resting conditions may indicate sites of scarring from an old myocardial infarction.
KARAN SINGH: Okay, yep, that looks good.
MIC CAVAZZINI: When you call Karan in, what are you asking him for?
AMANDA: He's just checking to see the quality of the scan, if there's any movements and also if the heart's able to be seen clearly in all of the images.
KARAN SINGH: Yeah so, I can't see any of those things that would impede accurate assessment of the heart. And so, we'll now move on to the stress component where we're administering an adenosine infusion to the patient. So, adenosine works to vasodilate coronary arteries, and so what we're trying to do here is increase blood flow through those coronary arteries into the left ventricular wall. And if you've got blockages in those arteries where they're unable to dilate as effectively, that'll show up on our scan as areas of relative underperfusion.
Partway through that adenosine infusion, we'll inject a higher dose of the same radiopharmaceutical and then make a comparison of the post stress pictures to the rest pictures and if there's regions that look different that might lend itself—that might indicate ischaemia.
But that's not to say that all blockages in the heart have a functional impact. If that was the case, then this type of test probably wouldn't exist. But we know that sometimes patients have blockages in the heart, but their vessels are still able to dilate, they're still able to provide blood flow to the left ventricle. And so, this is a good gatekeeping tool to push referrers in the direction of doing something interventional or optimizing their medical management.
MIC CAVAZZINI: Eduardo is already on optimal pharmaceutical management of his coronary artery disease and his cardiologist will want to know if revascularization is required. Myocardial perfusion imaging is less invasive than coronary angiography and can be particularly helpful in patients who are negative for cardiac biomarkers or red flags on ECG. A nuclear stress test may also be suitable for patients whose physique precludes effective stress echocardiography. Eduardo is removed from the scanner and moved into another room where the stress challenge will be administered.
KARAN SINGH: So, this is the part of the test where we'll give you that medicine, adenosine. Now that will increase the blood flow to your heart, and also widen some of the vessels elsewhere in your body. And so, you may feel some symptoms when we have the infusion running.
EDUARDO: What symptoms?
KARAN SINGH: You may get some chest pain. You may get some shortness of breath. Sometimes patients can experience a headache or flushing or some nausea. Those symptoms, once we stop the infusion, should disappear very quickly. So, within the first minute after the infusion, they should all be gone.
EDUARDO: A little bit scary.
KARAN SINGH: But we will be monitoring you throughout the test so you have ECG leads, and we'll keep checking your blood pressure, your heart rate, and we will be talking to you throughout if you feel like it gets too much of any time point, then please let us know and we can stop early as well.
EDUARDO: Sure.
KARAN SINGH: Alright, excellent.
MIC CAVAZZINI: Tranquilo. You’re in good hands, they will look after you well.
EDUARDO: Yes, I can see. And I speak with you.
KARAN SINGH: So, throughout the test, could you please move your legs up and down? Are you able to do that?
EDUARDO: I hope so.
KARAN SINGH: Yes, perfect. One by one. Just gentle.
EDUARDO: I’m very tired already.
KARAN SINGH: Just take it easy, not too hard, just gentle exercise. Thank you.
MIC CAVAZZINI: As the stress test is completed Dr Singh administers the second dose of radiotracer. Eduardo is relieved when told he can finally go and get some lunch while this infuses. Karan is then called to another room where a bone scan is being conducted. This patient is a man of 27 who earlier in the year had a car accident requiring fusion of cervical vertebrae. He’s recently been experiencing leg spasms and has been referred by his neurologist to investigate possible causes.
For bone scans the most commonly used tracers are methyl or hydroxy diphosphonate, again bound to the radioisotope Technetium-99m. Like normal circulating phosphates, these are absorbed into bone as it mineralises. A positive signal on this scan likely indicates a site of bone remodeling.
KARAN SINGH: So, Mic, here I'm looking at planar imaging of a bone scan. This patient was actually referred for leg spasms, but they've had previous spinal surgery up in the neck, so we'll do focused imaging of both the cervical spine but also the lower limbs. And so, as I'm looking at it, there are no overt sites of significantly increased osteoblastic reaction. So, what I'm going to do here now is ask the technologist to perform a SPECT/CT acquisition of the region of interest, and the thing that the team is querying is called heterotopic ossification, and that's when you can get bone formation outside of where bone should be. And so, we definitely should be able to pick that up on a bone scan.
MIC CAVAZZINI: When Dr Singh gets to writing up this report he notes that the targeted SPECT scans show mild radiotracer uptake around the hardware in the patient’s neck, but no abnormally intense signal around the pelvis or lower limbs to that would explain the patient’s pain or spasms. And the X-ray CT images provide no evidence of the heterotopic ossification that was being queried by the referrer.
Other pathologic processes that can be associated with a positive bone scan include infection, malignant disease and rarer conditions like fibrous dysplasia and osteoid osteoma. I’ll link to a review that explains how SPECT provides much greater detail and contrast than planar imaging which can help differentiate suspected skeletal pathology. Hybrid SPECT is even better, given that X-ray CT enables more precise anatomic localisation of radiotracer and also calibration of these signals for tissue density.
The limitation of any tomographic imaging, however, has always been long acquisition times and a restricted field of view that can be captured in one sitting. These constraints are now being overcome with more sensitive and longer-bore scanners that allow for fast acquisition of whole-body images. This technical advance has contributed to more accurate workups for bone metastases than traditional scintigraphy followed by targeted SPECT/CT of equivocal lesions. It also means less need for sedation in restless patients.
But let’s go back to the floor. As Karan and I are pacing the corridors, he is pulled aside to advise on a bone scan that’s been referred with a potentially more sinister indication. The patient is an infant with a fractured femur.
KARAN SINGH: I might get you to step out for this one. One of other indications that we do bone scans for, often infants and neonates, is for screening of non-accidental injury. So often, it's quite a heightened situation in the room and we can definitely talk about it and include it, but I might not get you to come in.
[Later] So, at the moment in room two we have a child that's been referred for assessment of non-accidental injury. And the bone scan is a really good whole-body assessment of fractures and bone bruising.
MIC CAVAZZINI: And so, who would be making that referral?
KARAN SINGH: Typically, the general paediatric teams, or sometimes the orthopaedic or neurology teams. Sometimes emergency departments will make that referral, because that's how these children may often first present to an emergency department, whether it be due to a fracture or injury or an unrelated reason and an injury was found at the same time. And often the findings that we see on bone scan will precede findings on X ray.
MIC CAVAZZINI: I'm thinking a hairline fracture that wouldn't necessarily show up well on a CT would be a hot spot.
KARAN SINGH: Yes. And very occult stress fractures. Bone scan is exquisitely sensitive at detecting those, particularly in the acute phase. As a nuclear medicine registrar, you may be involved in the assessment of children if your department services the paediatric hospital or the paediatric departments as well, in which case it's important to stay on top of paediatric life support and paediatric sedation requirements. Not for all scans, but for some scans, and for a certain age range of children. And so that’s another interesting thing to stay on top of. So, you still maintain your skills in acute medicine and resuscitation and emergency medicine while you're working in a setting that typically is a very outpatient-based specialty.
MIC CAVAZZINI: Over the next couple of hours Dr Singh flutters from one room to the next to check on more scan acquisitions. One is on a middle-aged woman with suspected gastroparesis. She’s been fed radiolabelled pancakes and is undergoing gastric emptying scintigraphy.
Then there’s an 84-year-old man with recently diagnosed heart failure due to left ventricular hypertrophy. He is being imaged with a delayed amyloid bone scan protocol, shown in recent years to be a very sensitive discriminator for transthyretin cardiac amyloidosis.
But not all the patients Karan sees today have come in in for diagnostic imaging. One is a 45-year-old man who will receive a radioisotope of iodine to treat a toxic multinodular goiter.
KARAN SINGH: So, his thyroid gland has lots of nodules in it and it's causing him to be in a hyperthyroid state. And unfortunately, the medications that are used for hyperthyroidism have some pretty rare but nasty potential side effects, including a significant decrease in your white blood cell count, which can cause severe infections.
And so, it's often safer, or one of the ways you can treat it is using radioactive iodine therapy, which we help to administer, and as registrars, you'll help to administer. And that will destroy some of that hyperactive thyroid tissue, such that you may actually render the patient hypothyroid and they need to take thyroxine. But that's a much safer medication in a much safer route to go down long term than it is to be on high dose medications for hyperthyroidism.
MIC CAVAZZINI: When we go in to see the patient, there is an elaborate dance involved in bringing out the radiopharmaceutical in a small lead-lined vial. The patient is told in great detail how once he’s swallowed the pill, he must swiftly exit the building and go straight to his parked car.
KARAN SINGH: I guess, for the purpose of explaining things, the radioactive iodine therapy can be administered as low dose therapy or high dose therapy. Low dose therapy is typically administered for benign thyroid disease, so everything but thyroid cancer. And so, this patient is getting a dose of 600 mega becquerels of iodine-131.
The iodine-131 that we're administering would emit beta rays, which would seek out thyroid cells and cause DNA damage. And a small percentage of the emissions are actually gamma emissions. And the iodine-131 has a half-life that's many days. And so, it's important, at least for the first week after they leave hospital that they that they practice radiation precautions and that's mainly to protect other people that don't need the radiation.
MIC CAVAZZINI: No public transport?
KARAN SINGH: You're right, it's advisable that they don't sit close to someone for prolonged periods of time, for the first few days.
MIC CAVAZZINI: Radioactive iodine is just the tip of the iceberg when it comes to therapeutic nuclear medicine, or what now gets termed ‘theranostics.’ By tweaking the radioisotopes attached to the tracer molecules, therapeutic doses of radiation can be delivered with incredible precision, and this had a particular impact in treatment of neuroendocrine tumours, lymphomas and meningiomas. Dr Singh describes how theranostics has revolutionised the treatment of prostate cancer.
KARAN SINGH: So, what we're doing here is we're imaging Prostate Specific Membrane Antigen, which is a protein that that's highly expressed in aggressive prostate cancers. And so PSMA PET/CT has proven to be another blockbuster application for nuclear medicine. What we're trying to do with gallium-labeled PSMA is we're trying to map where there is a high expression of Prostate Specific Membrane Antigens. It's proven to be excellent and accurate at staging of prostate cancer, re-staging in the setting of biochemical recurrence of prostate cancer. And then what we can do with that, then is we can swap out the gallium-68 with, most commonly lutetium, which is a beta emitter, and it will ideally go to the cells that have we've imaged and destroy those cells in setting of metastatic disease.
Okay, so maybe it'd be useful to run through this like I'm reporting a scan. So here we have a PSMA PET/CT examination of a 64-year-old male with recently diagnosed, biopsy-proven prostate cancer. And we're assisting with staging evaluation with a PSMA PET/CT. I can see here, as I zone into the prostate, there's abnormal, focal, intraprostatic PSMA expression within the right peripheral zone, posterolaterally at the mid-gland level in keeping with biopsy-proven prostate cancer. And we're able to quantify that tracer uptake there as well.
And, of course, as I move up into the remainder of the pelvis, I can see that right here within the pelvis, probably at multiple sites, there are PSMA-expressing lymph nodes, and they certainly express PSMA to the extent that would be diagnostic of locoregional nodal, metastatic disease. And as I'm moving through the rest of the body, I can see there's a small focus of mild PSMA expression in one of the right-sided ribs laterally. And this is where it's helpful, often to look at the underlying CT to understand what morphological abnormalities might exist in that area.
MIC CAVAZZINI: And I'm sure listeners have seen these before or can visualize them. But we've got a standard CT, full body on the left, and then on the right that's been overlaid with this—how would you describe a more blotchy palette from green to red.
KARAN SINGH: Correct. And there's no significant abnormalities there. So, I'm just going to park that for a second, because I know that on gallium-PSMA, PET/CT, it's not uncommon to have low grade PSMA expression in bone lesions that are ultimately found to be benign bone lesions. So, I'll just park that for the time being. But I can see here in one of the lumbar vertebral bodies, I can see an intense focus of PSMA expression.
MIC CAVAZZINI: Yep, it’s bright red on a background of green.
KARAN SINGH: Correct. And I can see here on the CT, there's a sclerotic focus there. So that bone there is more dense than surrounding bone. And so, certainly that would make me think of a skeletal metastatic deposit. Of course, there are, there are benign explanations for PSMA expression within bone—one of the main ones being vascular processes like hemangiomas—and so it's important to work through your differential diagnoses. But certainly, that degree of uptake, with that morphological appearance, that would be very suspicious for a skeletal metastatic deposit.
MIC CAVAZZINI: And then it's up to the oncology team to pursue that if they…
KARAN SINGH: Correct. And it makes a difference to the management of the patient. And it may very well not. It may make a difference if, for example, after local therapy, they want to institute some external beam radiation to a specific metastatic deposit. Or if it's causing pain, that may make a difference, but if they're instituting chemotherapy or something, it may not make a difference. So that's one example of how I would go through a PET/CT, and that's also how I would present the PET CT in the urology multidisciplinary team meeting.
MIC CAVAZZINI: Dr Singh participates in a handful of multi-disciplinary discussions every week. This afternoon it’s the breast cancer team meeting he needs to prepare for. On the list are fifteen patients, patients who have some complexity in their presentation or some turn in their management.
There are two main nuclear imaging modalities that contribute to investigations for breast cancer. Positron emission tomography is usually paired with the radiotracer FDG, or Fluorodeoxyglucose. This radioactive glucose is infused into the circulation where it’s then consumed by energy hungry cells as you’d find in rapidly dividing cancers. In other contexts it can used to identify active brain regions or sites of inflammation.
Karan shows me some scans from a 73 year old woman with biopsy-proven cancer in the right breast which shows amplification of the HER2 oncogene. Equivocal findings from a prior ultrasound of axillary lymph nodes prompted a referral for an FDG PET scan to help with staging. Fortunately, there are no signs of tracer uptake in the proximal lymph nodes or beyond, suggesting the cancer is currently localised to the breast. Another useful but non-specific way in which nuclear imaging can contribute to the workup of breast cancer is through a technique known as lymphoscintigraphy.
KARAN: And so, the purpose of a lymphocintigraphy study in a patient, is to identify the sentinel lymph node that breast might drain to. And the way we do that is by instilling a small amount of radiation around where the tumour is that gets sucked up by the lymphatic channels within the breast. And we're able to map the first lymph node that drains fluid from around where the tumour is.
And if the surgeons can just extract that one lymph node then send it off to pathologists for a detailed examination, and let's say that's negative and free of cancer, well then, you've saved the patient an operation whereby you're taking out all the lymph nodes within that nodal basin. Historically, they used to take them all out, and that left women often with less swollen and lots of side effects. And they found that they didn't need to do that for a lot of women.
MIC CAVAZZINI: So that lymphoscintigraphy is less prognostic than that is guiding the surgeon.
KARAN SINGH: Yes. So, the lymph nodes that we identify during our procedure—we're not telling people or whether they have cancer in them or not.
MIC CAVAZZINI: Okay, so that in that sense that it's not a tracer like FDG that's going into the cancerous cells. What are you labelling then?
KARAN SINGH: Locally, we use human serum albumin labelled to technetium. Injecting either subcutaneously or intradermally, utilizing the knowledge that that'll get picked up by the lymphatic channels and travel to lymph nodes.
MIC CAVAZZINI: And that drainage that's not standard anatomy?
KARAN SINGH: That's a good that's a good question.
MIC CAVAZZINI: Is the plumbing slightly different in different people, such that you can't predict which node it will be?
KARAN SINGH: Yes, definitely, because there are so many lymph nodes within the axillary basins. Some patients have sentinel lymph nodes that are higher up, some have sentinel lymph nodes that are lower. And sometimes, rarely, you get a sentinel lymph node that's in the other axilla. And so, you get drainage, or lymphatic drainage, from one breast all the way to the contralateral axillary nodal basin. And so really, if you didn't do that procedure and just scraped out some lymph nodes from here, said they were negative, or you would never know that they drained to the other axilla.
MIC CAVAZZINI: Interesting.
KARAN SINGH: Yeah, so that's the part I find most exciting. Whenever you get an unusual result and you're able to help the referrers. That’s always satisfying. For example, recently, we performed, here at Prince of Wales, our first oestradiol-PET for a patient with suspected metastatic breast cancer who had an FDG-PET, and some equivocal findings were noted elsewhere in the body, outside of the breast. And upon pathological examination, we came to know that the breast cancer was strongly oestrogen receptor positive, and so we performed an oestradiol-PET to, I guess, troubleshoot those equivocal lesions, and were able to confirm the presence of metastatic disease in those other lesions. And that drastically changed management.
MIC CAVAZZINI: When you say that was one of the first is oestradiol scans that you've done, how big a learning curve did that involve?
KARAN SINGH: It is a big learning curve because you're essentially reviewing, from an imaging standpoint, a different physiologic process. It takes time to familiarize yourself with the physiologic distribution of that tracer. So, you can see here that this is an FDG PET/CT scan, and the things that pop up the most to the eye on this whole-body projection are the kidneys and the bladder.
MIC CAVAZZINI: Which is the normal clearance pathway?
KARAN SINGH: Correct. And so equally, that, then, is a bit of a blind spot for FDG PET. And so different tracers have different excretion pathways so, it's important to understand these nuances. So, you get referred patients for, let's say, primary renal cancer. Yes, we may be able to make an assessment of staging, but we might not be able to make a local assessment of disease.
But going back to the purpose of what I’m doing here, I'm looking through the case to familiarise myself with the pertinent positive findings, pertinent negative findings, and understand if there's any nuances involved that may warrant discussion at today's multidisciplinary tumour board meeting.
Because these are specialists that want specialist opinions as well. And so, I guess as a registrar, acknowledging the limitations in knowledge that I have, I’ll often discuss these scans, particularly the complex ones, with my consultants prior to the meeting. Alternatively, there are some meetings where there are consultants present on site to review how I’m presenting scans. And as you become more confident or more familiar with a particular specialty that level of supervision might turn from direct supervision to indirect supervision.
MIC CAVAZZINI: I go and get myself a banh mi and meet up with Dr Singh again at the Nelune Comprehensive Cancer Centre. In a small room set up like a theatre, staff from right around the hospital drift in for the meeting. There are medical oncologists and radiation oncologists, surgeons in scrubs, cancer geneticists—about twenty people in all. Karan, takes a seat at a computer connected to one of three projectors, and pulls up the PET scans of the 73-year old woman that we’d been looking at earlier. Once the meeting starts, the case discussion is led by the patient’s breast surgeon.
KARAN SINGH: So, this is her FDG-PET. This was performed at the beginning of July. As you can see here, that primary right breast lower outer quadrant is only mildly active. Unfortunately, that does limit the sensitivity that test to screen for metastatic disease regardless, moving up towards that right axillary nodal basin, there's nothing that screams out as being involved. Obviously, with that caveat, as stated before that same goes for distant disease.
MIC CAVAZZINI: The pathologist takes over from Karan with her own slides and a battery of classification scores. Then the other specialists chime in. The patient is not keen on mastectomy. There aren’t great chaemotherapy options for this type of cancer, though there might be a research study the patient is eligible for. The team converges around whole breast radiation therapy as the best option.
As an outsider and non-clinician, it’s humbling for me to watch these experts pool their knowledge to help patients with one of the cruellest hands that nature can deal. There’s an earnest but collegiate atmosphere in the room that I can see brings Karan great satisfaction.
Over the day he makes several comments about aspects of his role as registrar that he particularly enjoys. And also, how the rapid evolution of the field keeps him enthused about the ever greater impact this specialty will have for diagnosis and prognostication.
KARAN SINGH: I just wanted to let people know that it's a really nice specialty to work in. On call is relatively less onerous than what it might be for some of the other medical specialties. Certainly, we do on call, and there are emergencies in nuclear medicine. The main two I can think of are performing -, or doing GI bleed studies for suspected gastrointestinal haemorrhage. Outside of those, there are very few emergencies in nuclear medicine, so it's mostly a Monday to Friday, kind of eight to five, eight to six specialty.
You get to work with everyone from neonates all the way to geriatric patients, and work across different specialties as well. And I think it's sitting at the forefront of personalized medicine. There is that interaction that you get with patients, and that's inevitably going to increase as theranostics becomes more commonplace within oncology and non-oncology treatment paradigms. And so, I'd imagine as that increases, the role of the nuclear medicine specialist is going to turn away from sitting at a computer and reading scans to being a more dynamic part of the MDT, having patient consultations, running clinics. And it's a very cerebral specialty, so that involves a lot of thinking and science and physics and chemistry and it as well.
MIC CAVAZZINI: We've already talked a bit about the different tracers, the different machines. Do you have to be a bit of a biophysics nerd to enjoy it? Or is there enough, you know, medicine medicine?
KARAN SINGH: Hah. I mean, it would be helpful if you're interested in those things. Like, I never did biology and I never did physics at school, and so for me, it was completely new. And so, you will be taught to everything that you need to know.
MIC CAVAZZINI: I can see a very faded periodic table of the elements on the wall. Pop Quiz, what's the molecular weight of cerium?
KARAN SINGH: See, I've got no idea. So, if you don't know the molecular weight of cerium, you're still fine to do nuke med. But you know, in nuclear medicine, we've got access to the whole periodic table, really. We also work with radiochemists or radiopharmaceutical scientists. And so, they're the ones that are focused on producing the radiopharmaceuticals that we use for imaging, and so that's very exciting. Really, some of these imaging, some of these agents, or receptors, rather, is stuff that we've never seen or done before, and there's untapped potential. And I think we need bright people to enter the specialty.
Like, it can be frightening and overwhelming but, you know, with repetition and learning and spending time the department, all this stuff is very easily and quickly picked up. I'd urge people to look at the skills, core skills that they have and the core skills they'd like to develop, when choosing a specialty. As opposed to thinking, “I like the science of oncology, so therefore I want to go into oncology”, because you’re not really thinking about the task that you're doing on a day-to-day basis.
MIC CAVAZZINI: And they're all going to get boring or frustrating after a while. So, how can you keep it interesting? And it sounds like nuclear medicine, allows the scope for research interests?
KARAN SINGH: Yes, yes. And when you're working in a robust department and you've got lots of people that are working to help flow of the department, often the first few hours the day might be slightly slower than the latter half of the day, because that's the time where patients are being injected or administered with their radioisotope, and then scanning might not commence till a little bit later. And so, there's ample opportunity and time to get involved with research quality improvement within the department, study for things like the basic sciences, bug the technologists about how the physics of all the cameras work. When you start nuclear medicine training, if you're not coming from an imaging background, it is very easy to feel quickly overwhelmed, but that that passes, and then you kind of can't imagine life not doing this.
MIC CAVAZZINI: Many thanks to Karan Singh for sharing his passion for this episode of Pomegranate Health. I’m also grateful to his colleagues, and particularly the patients, who tolerated having a fly with a microphone on the wall. Dr Singh encourages anyone who might be curious about nuclear medicine to go and visit their nearest department or even take up a resident position. A consultant on my review group noted that the case mix will be very different from one department to the next, and there are many interesting applications we haven’t even touched on today.
He is just one of a handful of College members who kindly volunteered their time to help improve early drafts of this podcast. I’ve thanked them all by name in the episode notes at the website racp.edu.au/podcast. There you’ll also find music credits and a full transcript. For some more explainer on the tracers and other technical details you’ve heard about today, I’ve embedded links from the StatPearls online textbook hosted by the National Library of Medicine. Within the College Learning series you’ll find a brief lecture title “Nuclear medicine investigations in paediatrics”
I hope today’s podcast got you thinking about different career pathways in medicine. Please share it round or leave a review at your favourite pod browsing app. And if you’d like to spend “a day in the life” in another department or healthcare setting, please email your ideas via the address podcast@racp.edu.au. I’m Mic Cavazzini. Thanks so much for listening.