COMMONLY PERFORMED INVESTIGATIONS

Commonly performed investigations

LUNG

Ventilation/perfusion (V/Q) scan:

The V/Q study is performed to detect pulmonary emboli within your lung blood vessels, these are small clots that block the blood flow to your lungs.

It is performed in 2 stages:

Stage 1: You will be asked to inhale a radioactive gas before you are placed on our specialised camera for imaging of your lungs.  This will allow us to evaluate the airflow in your lungs. Please note that this gas will not cause drowsiness or any other symptoms.

Stage 2: An initial baseline scan is performed, thereafter you will be injected, you will be injected intravenously with a small amount of a radioactive substance, followed by a second scan. These images are used to assess the blood flow within your lungs. 

A nuclear physician will evaluate and compare the two sets of images to determine if you have a pulmonary embolism.

No preparation is needed for this study. You can eat and drink normally before and after the study.

These scans are also safe to perform in pregnant patients and during breastfeeding; however, a specific protocol is then followed – please contact the practice for further instructions prior to your procedure.

Lung quantification: 

This study is used to determine what contribution certain parts of your lungs have to the total lung function. It is often used prior to surgical removal of part of a lung, to determine if enough lung tissue will be left post surgery to maintain adequate oxygen saturation. 

A radioactive isotope will be injected and images of your chest will be acquired. The contribution of each part of the lung will be calculated and reported to your referring doctor. 

No preparation is needed for this study, you may eat and drink normally before and after the study. 

Referring doctors, please inform us if your patient has pulmonary hypertension as the radiopharmaceutical preparation will need to be adjusted accordingly. 

CARDIAC

Myocardial perfusion imaging (MPI)/MIBI study:

This study is used to evaluate blood flow to the heart muscle and function of the left ventricle of the heart. There are multiple reasons why your doctor may request this study, including to aid in optimal therapy selection, to determine if there is any irreversible damage to your heart muscle after a heart attack or before a big operation to determine whether you may have any heart disease that may influence the surgery or anaesthetics. 

This study is performed in 2 stages, a rest and stress study. These are then compared and used to aid in answering the question of your referring clinician. 

Stage 1 – Rest study: You will receive an intravenous injection of radioactivity and imaging will commence ± 45 minutes later. 

Stage 2 – Stress study: This is performed after the rest study imaging is complete. During this part of the study, you will either do physical exercise (on a treadmill) or you will be injected with a medication that mimics the physiological effect of exercise on your heart (pharmacological stress test). The choice of stress method will be determined by your referring doctor and the nuclear medicine specialist in charge of the study.

Your ECG (heart rhythm) and other vital signs (blood pressure and pulse) will be closely monitored during this part of the study. Once your heart has reached the desired target, you will be injected intravenously with further radioactivity and images performed from ± 15 – 45 minutes after injection, depending on the type of exercise performed. 

Patient Preparation:

Correct preparation is of utmost importance for this study. Preparation depends on the type of exercise/stress method used. Please contact us if you are unsure about the preparation instructions or if you have any questions. Further information is also available on this website in our downloadable MIBI study brochure.  

General: 

  • No caffeine containing drinks/food/medications may be ingested 12 hours prior to the study. This includes, but is not limited to, coffee (including decaffeinated), normal tea, green tea, coke, chocolate etc. Rooibos tea is allowed. 

Please note that some over the counter medications such as Grand-Pa’s, Sinutabs, Sinucons etc. also contain caffeine and should therefore also be avoided. 

  • Please consume a light breakfast only or omit breakfast entirely and bring along some food to consume after the stress study.
  • Bring along something to do/read while waiting.
  • Please wear comfortable clothing and shoes to enable you to walk on the treadmill.

If physical exercise is being used for the stress study, then the following substances need to be withheld:

    • Beta-blockers (e.g. Atenolol, Propanolol and Carvedilol)  MUST be stopped for 3 days prior to the study. If for medical reasons this medication cannot be stopped, please let us know, as a pharmacological stress study will be performed instead.
  • Calcium-channel blockers (e.g. Amlodipine) should be stopped for 48 hours prior to the study if possible.

If pharmacological stress testing is used, the following substances should be withheld:

  • All xanthine-based compounds e.g. Theophylline (or similar) 5 days before the study.
  • Long-acting nitrates (Elantan or similar ) 3 days before the study.
  • Isordil/nitrolingual spray for at least 12 hours before the study.*
  • Patients taking medications containing dipyridamole (e.g. Dipyridamole Retard®, Plato®, Asasantin Retard®, Persantin Retard®) should discontinue their medication two days prior to a study using regadenoson or adenosine protocols.

* Please note, if you experience severe chest pain before the study and need to use your medication to relieve this pain (e.g. Isordil/Nitrolingual spray), you may do so, but please inform us that you have used it. We will then decide if the study needs to be rebooked or if we will continue.

Multigated acquisition scan (MUGA):

This study is used in the evaluation of your left ventricular ejection fraction (LVEF). LVEF is a measure, which is expressed as a percentage, of the amount of blood being pumped out of the left ventricle each time it contracts; it looks at how well your left ventricle pumps blood with each heartbeat. Several factors or diseases may cause an impairment in the way it contracts, these include previous heart attacks, viral infections, medications like chemotherapy or chronic diseases such as diabetes or hypertension. 

There is no preparation needed for this study. You may eat and drink normally before the study and medication may be continued as usual.

SKELETAL

Bone scan:

Bone scans are used in many different settings. It is unique in that it can image increased bone turnover from various conditions, at a very early stage, long before anatomical changes can be detected on other imaging. 

The most common use of a bone scan is to diagnose metastatic skeletal disease from various cancers – most commonly breast, prostate and lung, as these cancers usually cause a type of skeletal metastases (osteoblastic/sclerotic) for which bone scans have a high sensitivity (detection rate). 

It may also be used in benign (non-cancerous) conditions such as identification of bone infections, to determine the cause of pain after a joint replacement or in sports injuries (stress fracture versus shin splints). 

A radioactive injection will be administered intravenously. You will be asked to return 2-3 hours later for imaging.  In certain indications, we may perform some imaging directly after the injection as well. 

No preparation is needed for this study. You may eat and drink before and during the study. We encourage you to drink at least 4 glasses of water after the injection to improve the image quality and excretion of the radioactivity. The study will take approximately 3-4 hours to be completed, from time of injection to completion of the images. You do not have to wait at the practice between the injection and the imaging time. 

KIDNEYS

RENOGRAM:

 

Renogram:

This study is performed to evaluate your kidney function. There are many different reasons why your referring doctor would ask for this study, most commonly to see if both kidneys are functioning equally or to make sure that there is no obstruction (blockage in the flow of urine).

The study takes about 1 hour to complete. 

 

The nuclear physician will then look at your scan and interpret the findings. Your report will be sent to your referring doctor.

Please drink enough water the day before and the morning of the study to ensure that you are not dehydrated. No further preparation is required.

Cystogram: 

The cystogram is used to determine if there is “reflux” into the kidney (any flow of activity from the bladder back into the kidneys) especially during times of increased pressure, such as during emptying of your bladder. A renogram (as described above) will also be performed prior to the cystogram. 

We will ask you to empty your bladder while sitting in front of the camera. Patients that are booked for this investigation must be able to follow instructions and pass urine when asked to, i.e. toilet trained children only.

Please drink enough water the day before and the morning of the study to ensure that you are not dehydrated. No further preparation is required.

DMSA: 

A DMSA study is used to look at the cortex (outer part) of the kidneys, to determine if infection or injuries to the kidneys have caused permanent damage (scarring). It is also used to determine what each kidney contributes to total renal function (differential function), specifically relevant in patients with kidney tumours. 

Radioactivity is injected intravenously and images are performed 2 hours later; the total imaging duration is ± 30 minutes.

Please drink enough water the day before and the morning of the study to ensure that you are not dehydrated. No further preparation is required.

BRAIN

Brain perfusion scan:

These scans are used to assess the pattern of blood perfusion (flow) to your brain. It is most commonly used to assist with the diagnosis or confirmation of various types of dementia however, there are many other reasons for referral. 

A detailed history is very important and the attending nuclear physician will interview you prior to the study. 

On the day of the study an intravenous cannula is placed, you will then lie in a dark and quiet room. Please switch your cellphone off during this time. If there is someone accompanying you, they are NOT allowed to talk to you during this period. You must relax, you may close your eyes, but please do not fall asleep. After ± 30 minutes the radiographer or doctor will enter the room and inject the radioactive substance. Please do NOT talk to the radiographer when he/she enters the room. After the injection, you will wait another ± 10 minutes before we fetch you for imaging, during this period you may continue with normal activities such as talking or reading; however, during the scan we ask you to remain quiet again. The scan takes ± 30 minutes to be completed. When the scan is done you may go home and continue with normal daily activities. 

Please do not take any sedatives the morning of the study. You must also not drink/eat any caffeine containing drinks or food. Please send us a list of medication prior to coming for the study as there are certain medications that may need to be stopped. 

ENDOCRINOLOGY

Thyroid scintigraphy/thyroid uptake scan:

This study is most commonly performed in patients found to have an overactive thyroid gland.  An overactive thyroid gland results in an increased metabolism in your body which causes symptoms such as loss of weight, palpitations, anxiety and insomnia (difficulty in sleeping). Many other symptoms may also be experienced. 

This study is performed to determine the cause of your overactive thyroid and to determine what therapy will be best suited for treatment.

You will be injected with a small amount of radioactivity intravenously; 20 minutes after the injection, images of your thyroid will be acquired on our specialised camera. 

The study will be interpreted by a nuclear medicine physician. If your doctor has requested radioactive iodine as treatment for your overactive thyroid gland, and if our imaging findings establish that you are a suitable candidate, we will calculate the amount of radioactive iodine required for treatment. Further information is available regarding radioactive iodine therapy on this website in our downloadable brochure.

After the investigation you may go home and continue with your normal daily activities. 

Patient preparation:

  • Please inform the staff if you are on any medication including Neomercazole/carbimazole, Eltroxin, beta-blockers, amiodarone, lithium or if you have had a recent CT scan when you are making the booking. These will influence the scan date and possibly our interpretation of your scan.

There is no further preparation needed for the study. You may eat and drink normally before and during the study.

Other indications: Thyroid scintigraphy may also be requested in the work-up of congenital hypothyroidism or assessment of hot/cold nodules.

Perchlorate discharge test:

This test is used to assist in determining the cause of congenital hypothyroidism. This is important for treatment, prognosis and genetic counselling. 

 

Patient preparation

  • Due to practical reasons, it is preferred to perform the study in children older than 3 years, after a period of thyroid hormone withdrawal (1 month). The TSH level of the patient should be known prior to the study.
  • For neonates the study should be performed as soon as possible prior to starting thyroid hormone replacement therapy and it is therefore urgent. It is rarely performed as the ordering of I-123 iodide may delay therapy initiation. 
  • The rest of the preparation is the same as for thyroid scintigraphy (see above).

 

You will be injected with a small amount of radioactive iodine intravenously; 20 minutes after the injection, images of your thyroid will be acquired on our specialised camera. Two hours after the initial injection, we will give you a perchlorate tablet to drink. This medication is used to see if any of the iodine activity that was injected in the beginning of the study can be washed out of your thyroid. We will then take images at 60 min, 90 min and 120 min after ingestion of the perchlorate tablet. The total duration of this study from the beginning until the end is approximately 4-hours.

 

PARATHYROID SCAN:

 

Your parathyroid glands are usually 4 small glands located just behind your thyroid gland, sometimes there are more or fewer glands or they may be located at an abnormal position (ectopic). Their main function is to regulate calcium levels in the body through influences of hormones such as parathyroid hormone. Hyperparathyroidism is when your parathyroid glands create too much parathyroid hormone in the bloodstream. An overactive parathyroid gland can be caused by an enlarged gland or as the result of another disease. This study is performed to aid in diagnosis and localisation of these overactive parathyroid gland/s. Prior to surgical removal of an overactive gland/glands, localisation with this study will assist in guiding the surgeon to their location and may avoid performing an unnecessary large surgery (minimally invasive surgery). 

 A radioactive substance will be injected intravenously, imaging starts 20 minutes after the injection followed by further image acquisition at 2 and 3-hour after the initial injection. 

Sometimes, a second radioactive injection will be given on the day of the surgery. The surgeon will use this to localise the overactive gland/glands during surgery using our specialised gamma probe. 

Preparation

Vitamin D therapy might reduce radioactivity uptake and drugs used to suppress parathyroid hyperfunction should also be withheld. Please discontinue using:

  • active vitamin D therapy at least 1 week before your appointment;
  • native vitamin D at least 4 weeks before your appointment;
  • Calcimimetics at least 2 weeks before your appointment.

Please also inform us if you are taking any thyroid hormone replacement such as Eltroxin/Thyroxine or other medications such amiodarone or lithium as we may need to stop these for a recommended period. A recent CT scan may also impact the scan quality so please inform us about this if you have had one recently. 

You may eat normally before, during and after the study. 

ONCOLOGY

 

Iodine wholebody scan (I-123/I-131):

This study is performed in patients with follicular or papillary thyroid cancer. It is used to assess if there is any disease left after surgery or to evaluate for metastatic disease. The first study will be performed after your thyroid has been removed, this is to determine if there is any thyroid tissue left (often microscopic that the surgeon could not see with their eyes) and/or if any metastases (cancer spreading to other areas in your body) are present. It is also used routinely for follow up in patients with known thyroid cancer to check if the cancer has recurred or worsened. The period between follow-up visits will depend on the state of your cancer; it may be yearly or more frequently if there is a concern for disease having returned.

The study is performed over 2 days, the radioactivity is given in a tablet form on a Wednesday and imaging performed a day later.  


In some instances, (when I-123 is not available), I-131 may also be used. Preparation before the study is the same as for I-123.

Patient Preparation:

    • For accurate results we require that your TSH level is equal to or higher than 30 IU before we may perform the study, as well as during the study. PLEASE DO NO RESTART YOUR ELTROXIN BEFORE THE SCAN, EVEN IF YOUR TSH LEVEL IS AT THE APPROPRIATE LEVEL as this will cause the scan to be unreliable and may miss metastases.
  • To achieve the desired TSH level, it will be necessary to stop your thyroid hormone replacement therapy:
  • Eltroxin or Thyroxin for 4-6 weeks;
  • T3 for 2 weeks;
  • If you do not wish to stop your medication you may take Thyrogen for 2 days before the scan. Please note that it is your responsibility to obtain an authorisation letter from your medical aid if you would like to use Thyrogen

 

I-131 POST-ABLATION SCAN:

After you have received your treatment dose of I-131 for your thyroid cancer, you will come to our department for a whole body scan. This is to determine if the I-131 has reached all the areas that showed abnormal uptake on the I-123 scan (i.e. residual disease or metastases). This study is usually performed a minimum of 7 days after you have received your therapy, but may be as long as 14 days after therapy. The amount of days will depend on various factors, for example what dose you received etc. as well as when you are discharged from hospital after your treatment.

After the therapeutic dose of I-131 your referring doctor will start/restart your Eltroxin. You may then take this tablet as before. No further specific preparation is needed before the study.

I-123/I-131 MIBG:

MIBG is a noradrenaline analog and can be used to diagnose certain types of cancers/growths of the adrenal glands known as pheochromocytomas; if these tumours are found outside the adrenal glands they are called paragangliomas. MIBG may also be used in Neuroblastoma, a cancer most commonly found in children under 5 years.

Patient preparation:

  • There is a long list of medication that needs to be stopped prior to the investigation. We will contact you when making the booking to get a list of the medication you are taking
  • If you are booked for the study, please do not take any over the counter medication before discussing with us, these include medications used for a cold, flu, blocked sinuses or even pain medication, as these also need to be stopped for a certain amount of time. 
  • Please note that this radioactivity is specifically ordered for you, if you do not follow the correct preparation we will not be able to do the study. If we do perform it without knowing that certain medications were not stopped, we will not get reliable results and may miss important findings.  

The advantage of MIBG is that it can be used for diagnosis and therapy, if we can prove that your tumour does take up the radioactivity, I-131 MIBG may be considered as a treatment option in consultation with your oncologist. 

Sentinel lymph node study:

This study is typically performed in patients with breast cancer, malignant melanoma or head and neck cancer. It is performed the day before or on the day of your surgery. It is used detect to which lymph node/s your tumour drains to first i.e. the first site that the cancer may have spread to. It is a “roadmap” for your surgeon, assisting the surgical team in selection of which nodes to remove for evaluation. Please note that uptake of activity on the scan is NOT indicative of cancer in the nodes. The removed lymph node/s will be evaluated by a pathologist for cancer.

The radioactive substance will be injected just under your skin in the area of your tumour (or scar), a very thin and small needle is used.  You will be placed under the camera immediately and images will be acquired for ± 30 minutes. More images are taken at 1-2 hours after administration of activity, depending on varying factors. 

There is no preparation needed for the study. You may eat and drink normally before and during the study.

GASTROINTESTINAL STUDIES

GASTRIC EMPTYING STUDY:

This study is used to determine whether your stomach empties at a normal rate or not. We will give you a small meal consisting of egg and bread which has been mixed with some radioactivity. 

After eating this radioactive meal, we will acquire images for 30 minutes and then every hour up to 3 or 4 hours. 

Your “gastric emptying rate” will be calculated and a report sent to your referring clinician.

Patient preparation:

  • You may not eat or drink anything for 4 hours before the study, ideally you should not have any food or drink from midnight before the study.
  • Certain medications may affect your gastric emptying rate, we request that you do not take these for 2 days before the study:
    • Opioids for pain relief (e.g. morphine, tramadol);
  • Anti-nausea medication (e.g. Stemetil, Maxolon);
  • Anti-diarrheal medication (e.g. loperamide/Immodium);
  • Medication for stomach cramps (e.g. buscopan).

If you are uncertain if you are allowed to take your medication, please contact us for clarification.

  • Diabetic patients: your sugar needs to be less than 11 mmol/l before you start eating your meal. Please ensure that you bring insulin with to use after the meal. If your sugar is too low the morning of the study please rather eat something and let us know so that we may reschedule the study, low sugars are dangerous for your body.

 

Gastrointestinal (GIT) bleed study:

This study is used to detect small bleeds in your bowel, that cannot be detected by the usual methods. It is important that this study is booked WHILE the patient is having an episode of gastro-intestinal bleeding.

We draw blood from you and then label your red blood cells with radioactivity in our laboratory. A while later we re-inject your blood that has been labelled with radioactivity and start with the imaging procedure. You will be on the camera for roughly an hour initially, followed by further imaging at hourly intervals after this. We may even need to take images at 24-hours after the injection all depending on what the findings are.

We use these images to identify sites of possible bleeding in order to guide your surgeon where the bleed is coming from for further management.

There is no preparation needed for the study. You may eat and drink normally before and during the study.

 

Meckel’s Diverticulum study:

Meckel’s diverticulum is the most common cause of lower gastrointestinal (colon) bleeding in young babies. It is a congenital abnormality of the gastrointestinal tract (parts of the digestive system). This study is performed to identify ectopic (abnormally located) stomach tissue in the Meckel’s diverticulum, which is typically located in the distal part of the small bowel, that may be causing bleeding in your bowel. It is important that the patient is not currently bleeding. If the patient is bleeding at the time of the request, a red cell study for GIT bleeding would be the study of choice. 

Patient preparation:

  • It is ideal for the patient to be fasting of 3–4 hours before the study however, this is not essential.
  • The use of all drugs or procedures that may irritate the gastrointestinal tract should be stopped for 2–3 days before the study if possible; your referring doctor can liaise with us about this and advise you further.

 

Hepatobiliary study:

This study is requested to look at the biliary system (organs and ducts – tubes e.g. bile ducts and gallbladder – that are involved in the production and transportation of bile). It can be used to determine if the gallbladder is contracting properly, whether you have acute or chronic cholecystitis (inflammation of the gallbladder) or if there is an obstruction of the biliary system. In newborn babies it is used to assess for biliary atresia (a blockage in the tubes that carry bile from the liver to the gallbladder).

Patient preparation:

  • You need to be fasting for 4 hours, but not longer than 24 hours. 
  • Medication that needs stopping:
  • Opioids such as morphine or tramadol must be stopped for a duration of time. Please contact our practice for further details. 

Milk scan: 

A milk scan is mostly commonly used to assess for possible reflux in a child. Other indications include assessment of swallowing and gastric emptying in children.

It can be performed as early as 4 weeks after birth, but if the swallow needs to be evaluated, then the child must be able to drink a bottle.

A small amount of radioactivity is mixed with breastmilk or formula; the baby is then fed with this followed by normal milk. Please bring along at least 2 full bottles of milk or formula.

Patient preparation

The patient should have nothing by mouth or by tube feeding prior to the examination. The length of time that the patient should refrain from intake depends on the patient’s age and the clinical circumstances, but in most cases 4 hours would be sufficient

HAEMATOLOGY

Red cell volume:

This study is performed to evaluate for true polycytaemia vera (production of too many red blood cells) versus relative polycytaemia (an apparent rise of the red blood cells caused by factors such as lowered fluid intake or increase fluid loss – diarrhea, vomiting etc)

The procedure involves taking a blood sample from you which is labelled with a small amount of radioactivty and then re-injected into your vein. We require you to sit still for 15 minutes to allow for the blood to mix and then we take two blood samples from you again at 10- and 30-minutes after the re-injection of your blood.

Patient Preparation

No venesection (removal of your blood) or blood transfusion in the 4 weeks prior to the study.

You may eat and drink normally before and during the study.

Splenic scintigraphy (damaged red blood cell study) 

This study is performed in instances when an accessory spleen is suspected, in evaluation of a splenic infarct or to look for residual splenic tissue after a spleen has been surgically removed for medically reasons.

The procedure involves taking a blood sample from you which is labelled with a small amount of radioactivity and then re-injected into your vein, followed by imaging.

There is no preparation needed for the study. You may eat and drink normally before and during the study.

 

INFECTION IMAGING

There are various Nuclear Medicine studies that may be performed to aid in diagnosing infection. Your referring clinician will liaise with us prior to the study to discuss what the most appropriate investigation would be for you.

Bone scan: 

This is used for suspected infections involving bone most commonly referred to as osteomyelitis. A three-phase bone scan is usually the first investigation. If the bone scan does not show any typical abnormalities, then a bone infection is ruled out and no further imaging is needed. Reasons for referral include suspected joint prosthesis infection or osteomyelitis. 

For further information regarding preparation etc., please see the section on bone scan above.

 

Labelled white blood cells: 

This study is also performed to assess for any sites of infection in your body. White blood cells are the soldiers of our bodies and aid in fighting infections when we are sick. During an infection, these white blood cells clump together to try and kill the infection. 

Your blood will be drawn and your white blood cells labelled with a small amount of radioactivity. Your own blood will then be re-injected into your veins followed by imaging at 30-minutes, 3-hours and 24-hrs after injection. 

On these images we are able to identify where the radioactive white blood cells accumulate, thereby indicating the site of infection. This can guide your clinician with further therapy decisions. 

Please note that strict aseptic techniques are used when working with your blood and blood products, to ensure that we do not give you an infection. Strong quality control measures are in place to ensure a very high standard of care.

Referring doctors: please ensure that the patient has a large patent vein for venous access, we need good flow of blood when we draw blood. If the patient does not have good venous access, please would you place a CVP. Please also send the patients latest ESR and white blood cell count with the request form. 

There is no preparation needed for the study. You may eat and drink normally before and during the study.

 

F-18 FDG PET/CT (Fluorine-18 Fluoro-deoxy glucose positron emission tomography):

PET/CT is also a nuclear medicine imaging technique, but uses a different type of camera and a slightly different type of radioactivity (positron emissions) when compared to all of the above studies.  The most common use for F-18 FDG PET/CT is in cancer imaging, but it is also a very sensitive and valuable tool in diagnosing infection.  

We administer an intravenous injection of radioactivity and start imaging at 45 – 60 minutes after injection, depending on the type of infection we are looking for. Duration of imaging is approximately 20 – 30 minutes.

There are a few important points regarding preparation, please see our dedicated website  for the Cape PET/CT centre for  further information.