Commonly Performed Investigations - Morkel Nuclear Medicine
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Commonly Performed Investigations

Commonly performed investigations

Ventilation/perfusion (V/Q) scan:

The V/Q study is used to detect pulmonary embolisms (small clots that obstruct the blood flow to your lungs)

It is done in 2 parts – the first part you inhale a radioactive gas so that we can see how air is distributed within the lungs. We then put you under the camera and scan your lungs from different directions.

After this we inject you with a different radioactive substance – this will show us how blood flows in the vessels within the lungs. After this we again put you under the scanner to take images of you lungs.

A nuclear physician will then look at the 2 studies and compare them 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.


Myocardial perfusion study:

This study is to determine if there are obstruction in the blood flow to your heart muscle.

This study is done in 2 parts;

The one part is called a “stress” study and the other is called a “resting” study.

For the “stress” study there are different ways we can “exercise” you to get the desired effect: we will do it either by letting you run on a treadmill OR if you are unable to do physical exercise we will inject you with medication to make the heart act similar to when you exercise.

The choice of exercise method will be determined by your referring doctor and the nuclear medicine specialist in charge of the study.

After the exercise we will inject you with a radioactive substance and we will then put you on the scanner after a predetermined time. The radioactive substance (MIBI) will show us how the blood is flowing within your heart muscle.

For the “resting” part of the study we will also inject you with a radioactive substance and put you under the scanner to do the imaging.

After all the imaging is done – a nuclear physician will look at the images and compare the 2 different sets of images to determine if there are a problem with the blood flow in your heart muscle.    

No caffeine containing drinks/food”/medications (eg coffee (even decaf), tea (except rooibos), chocolate, “Grand-pa’s”)
The following medication should preferably be stopped before the study:

  • If exercise test (on treadmill) will be done:
    • Beta-blockers (Atenolol, Propanolol ,Carvedilol) : 3 days
    • Calcium-channel blockers (Amlodipine) – if possible: 2 days


If Persantin study will be done:

  • Long-acting nitrates (Elantan) – specifically if Persantin study will be done : 3 days
  • Theophylline (or similar) : 5 days
  • Isordil/nitrolingual spray : 12 hours before the investigation – if however you experience severe chestpain rather use the medication as instructed by you treating physician and inform us. We will then decide if the study needs to be rebooked or if we can continue.


Bone scan:

Bone scans are used in many different settings – amongst others it can be used to diagnose benign disease for example to diagnose bony infections, sports injuries or to detect pathology after a joint replacement. It is also often used in malignant diseases, mostly to detect skeletal metastases.

You will be injected with a radioactive substance that gets taken up in your skeleton. You must then wait 2-3 hours before we can do the scan – during this time you can eat and drink normally. We encourage you to drink lots of water to help with the excretion of the radioactive substance and also to help to improve the uptake and therefore our images.

For certain indications we will inject you while you are lying under the camera, these images will take about 20 minutes. You must then still come back for more images 2-3 hours later.

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 our image quality and improve excretion of the radioactivity.



This study is done to evaluate your kidney function. There are many different reasons why your referring doctor would ask for this study. Usually it is to see if both kidneys are functioning similarly or to make sure that there is no obstruction.

The study takes about 1 hour to complete. We inject you with a radioactive substance while you are lying under the camera. We will then take pictures for 30 minutes. We will then ask you to empty you bladder and do a few more studies. The doctor will then look at your scan and interpret the findings.

Your report will be sent to your referring doctor.

Make sure you are not dehydrated when you come for the study. Please drink enough water the day before and the morning of the study. No other preparation is needed


Brain perfusion scan:

These scans are usually done to look at the blood flow in your brain. We will ask you a few questions and to get a history from you before we start with the examination.

We will put up an IV cannula and let you lie in a fairly dark room to relax before the study. You must please switch off your cell phone during this time. If there is someone accompanying you they are NOT allowed to talk to you during this time. You must relax and you may close your eyes, but you must please try not to fall asleep. After about 30 minutes a radiographer will enter the room and inject you with a radioactive substance. You must NOT talk to the radiographer when he/she enters the room. After the injection we will wait about 10 minutes before we come and fetch you. When this time is over you can continue with normal activities (eg talking, reading) while waiting for us to do the images.

The scan takes about 30 minutes to be completed. When the scan is done you can go home and continue with normal daily activities.

A nuclear physician will interpret the study and the report will be sent to you referring doctor.

You must not take any sedatives the morning before the study. You must also not drink/eat any caffeine containing drinks or food.


Thyroid uptake scan:

This test is usually done when your referring doctor have found that your thyroid gland is overactive.

We will inject you with a radioactive substance that gets taken up by the thyroid gland. 20 minutes after the injection we will put you on the camera and take pictures of your thyroid gland. Occasionally we will ask you to have a drink of water and we will take some more pictures.

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

Please inform the staff if you are on any medication (eg Neomercazole, Eltroxin, beta-blockers, Amiodarone) when the booking is made, as this may influence interpretation of your scan.

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


Parathyroid scan:


Your parathyroid glands are small little glands located just behind your thyroid gland. Its main function is to regulate your calcium levels. Your doctor have diagnosed that your glands may be overactive.

You will be injected with a radioactive substance – 5 minutes later we will start with imaging. The first part of the study will take 30 minutes. Thereafter we will do images at 2 hours and 3 hours after administration of the radioactivity. The 2 hour images will include a study where the camera will rotate around you. This part of the study will take the longest (up to 20minutes).

In certain situation we may inject you with a 2 different radiopharmaceuticals. The first injection will be given and after 20 minutes images will be taken. These images will take about 10 minutes. The 2nd injection will then be administered while you are still on the camera. Imaging will then be done in the same manner as described above.

You should inform us if you are on Eltroxin when the booking is made. We might have to stop this before this investigation. Calcimimetics and Vitamin D supplements must also be stopped before the study. In addition it is preferable that you should not have had any diagnostic imaging with intravenous contrast in the 4 weeks prior to the study. Please contact us to discuss your unique case with us before the study.



I-131 post-ablation scan:

After you have received your THERAPEUTIC I-131 for the treatment of your thyroid cancer, you will come to our department for a whole body scan. This is to determine if the I-131 has gone to all the areas that still showed uptake on the I-123 scan. This study can be done 2-10 days after you have received your I-131 dose. The timing of the study depends on when you are discharged from hospital after your treatment.

After the therapeutic dose of I-131 your referring doctor will start/restart your I-131. You can take this tablet as before. NO other specific preparation is needed before the study.

I-123 Wholebody scan:

This study is performed in patients with a certain type of thyroid cancer. The first study will be done after your thyroid has been removed – this is to determine if there are any thyroid tissue left and/or if any metastases are present. It is also used for follow-up in patients with (previous) thyroid cancer.
The radioactivity gets administered in a tablet-form. A day after administration (24 hours) of the radioactivity you must please come back to our department for the images.
In some instances (when I-123 is not available), I-131 can also be used. Preparation before the study is the same as for I-123
Preparation before the study is of utmost importance For accurate results we require that your TSH level is >30IU before/during the study. To achieve this it is necessary to either stop your thyroid hormone replacement therapy (eg Eltroxin or thyroxin) for 4-6 weeks before the scan OR 2 weeks if you are takin T3. If you do NOT wish to stop your medication you may take “thyrogen” before the scan – (You will need to get medical aid authorisation for this). Please see the section on Thyrogen (under preparation before studies).
If you decide to rather stop your hormone replacement your TSH level will have to be done 1 week before the study (before we order your dose.) This is to verify that your TSH level is appropriate before the study. PLEASE DO NO RESTART YOUR ELTROXIN BEFORE THE SCAN, EVEN IF YOUR TSH LEVEL IS AT THE APPROPRIATE LEVEL – this will cause the scan to be unreliable.

Sentinel lymph node study:

This study is done the day before or the day of your surgery. It is to detect to which lymph nodes your tumour drains first. This lymph node (s) will then be removed during surgery and evaluated by a pathologist.
The radioactive substance will be injected just underneath your skin in the area of your tumour (or scar). You will be placed under the camera immediately and images will be done for about 30 minutes. Images will also be done 1-2 hours after administration of activity depending on varying factors.
Uptake of activity on the scan is NOT indicative of cancer in the nodes. The absence or presence of cancer in the nodes can only be determined after evaluation by the pathologist. Our images only serves as a “roadmap” to tell the surgeon which nodes to remove for evaluation.
There is no preparation needed for the study. You may eat and drink normally before and during the study.


Gastric emptying study:

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

After eating this radioactive meal we will take images for 30 minutes and then hourly up to 3 or 4 hours.

We will then calculate your “gastric emptying rate” which will then be reported and sent to your referring clinician.

You may not eat 4 hours before the study.

Certain medications may affect your gastric emptying rate, we request that you do not take these for 12 hours before the study. This includes opioids for painrelief (eg morphine, ,tramadol), anti-nausea medication (stemitil, maxolon), anti-diarrheal medication and medication for stomanch cramps cramps (buscopan, immodium). If you are uncertain if you are allowed to take your medication please contact us for clarification.