Clinical Protocols (Non-Therapy) Flashcards
What is the mechanism of physiological uptake in a Lung Ventilation scan?
The micro-aerosol particles are small enough to reach the DISTAL TRACHEOBRONCHIAL TREE and reflect REGIONAL VENTILATION
NB: Aerosols are suspensions of very fine particles that are deposited in the ALVEOLI
With regards to LUNG VENTILATION; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- Technetium-99m
- DTPA (Pentate aerosol)
- 40 MBq (800 is dispensed, but 40 makes it to the lungs)
What is the clinical need for a LUNG VENTILATION scan?
How is this affected if the patient is pregnant?
Lung ventilation shows the SHAPE of the lungs, and establishes if PERFUSION DEFECTS match.
For pregnant patients: Only acquire if the perfusion image is abnormal
With regards to LUNG VENTILATION; can you tell me what camera acquisition settings are typically used in NHST?
1. Collimator
2. Matrix Size
3. Energy Window
- LEGP
- 128x128
- γ-emission: 140.5 keV photopeak;
Window settings at 141 keV with 20 keV width
What does MUGA stand for?
MUlti Gated Acquisition.
Used in blood pool imaging
What is the clinical need for a MUGA scan?
It is a common study for patients receiving CARDIOTOXIC CHEMOTHERAPY
Would also accept any of:
1. Acute Myocardial Infarction (AMI)
2. Coronary Artery Disease (CAD)
3. Assessment of drug therapy
4. Pulmonary disease
With regards to a MUGA scan; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- Technetium-99m
- Tc-99m labelled PERECHNATE
Also pre-administration of stannous ions 30
mins before radiopharmaceutical - 800 MBq
What is the mechanism of physiological uptake in a MUGA scan?
Tc-99m must be in an OXIDATED state to cross the ERYTHROCYTE MEMBRANE
BUT only tc-99m that has been REDUCED into a lower state will bind firmly to HAEMOGLOBIN
Stannis is used as the REDUCING AGENT for Tc-99m
Combination of both with delayed phase allows for diffusion of stannous into the blood pool so that Tc-99m tracer binds to blood cells
How would you process a MUGA scan?
The ECG time gated images are analysed by applying ROIs around the LEFT VENTRICLE of the heart.
The measured counts during DYASTOLE (EDV) & SYSTOLE (ESV) are used to calculated the LEFT VENTRICULAR EJECTION FRACTION (LVEF)
Normal LVEF @ Baseline is > 50%
Therapy is stopped if LVEF decreases by > 10 from baseline or if LVEF falls < 50%
If < 30% Therapy would not begin
With regards to a MUGA scan; can you tell me what camera acquisition settings are typically used in NHST?
1. Collimator
2. Matrix Size
3. Energy Window
- LEGP
- 64x64, 24 bins (dynamic ECG gated) with the heart filling at least 50 % of the FOV
- γ-emission: 140.5 keV photopeak;
Window settings at 141 keV with 20 keV width
What is the clinical need for an MPS scan?
An MPS study looks at how well blood flows THROUGH your HEART MUSCLE
May be referred for indication of:
1. Chest pain
2. Coronary artery disease (CAD)
3. To look for HEART MUSCLE DAMAGE after a HEART ATTACK
With regards to an MPS scan; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- Tc-99m
- TETROFOSMIN (for binding to RN); if stress phase + RAGADENSON as a pharmaceutical stressing agent
- 800 MBq per Stress/Rest
- If BMI > 40, ARSAC approval for 1200 MBq
per stress/rest in NHST (Seeking to change)
- If BMI > 40, ARSAC approval for 1200 MBq
What is the mechanism of physiological uptake in an MPS scan?
Tc-99m TETROFOSMIN is LIPID SOLUBLE and so diffuses from the blood into the MYOCARDIAL CELL.
It is RETAINED INTRACELLULARLY in the region of the MITOCHONDRIA because of its NEGATIVE TRANSMEMBRANE POTENTIAL
The radiopharmaceutical remains FIXED WITHIN the MYOCARDIUM
With regards to an MPS scan; can you tell me what camera acquisition settings are typically used in NHST?
1. Collimator
2. Matrix Size
3. Energy Window
- LEHR
- 64x64 (512x512 CT(60)) - SPECT acquisition imaging
- Since it is SPECT imaging, requires 2 acquisition windows, for photopeak and for scatter window:
Emission Window:
γ-emission: 140.5 keV photopeak;
Window settings at 141 keV with 20 keV width
Scatter Window:
Window settings at 120 keV with 10 keV width
How would you process an MPS scan?
Visual inspection of the three main views of the heart. Images are registered to CT to provide attenuation correction.
The three analysis views:
1. Short Axis - O
2. Vertical Long Axis - U
3. Horizontal Long Axis - ⸧
What is the clinical need of Lymphoscintigraphy?
Assesses the DRAINAGE of the LYMPHATIC SYSTEM - Sentinel Lymph node drainage
- Referred for indications of OEDEMA (Protein-rich fluid build up/swelling)
With regards to a Lymphoscintigraphy; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- Tc-99m
- Nanocolloidal Human Serum Albumin (NHSA)
- 20 MBq/Limb
What is the mechanism of physiological uptake in Lymphoscintigraphy?
COLLOIDAL AGENTS are used as these particles enter LYMPHATIC CHANNELS and MIGRATE to LYMPH NODES where they are RETAINED by MACROPHAGES
The radiotracer is inkected INTRADERMALLY, usually between the fingers or toes of each limb.
With regards to Lymphoscintigraphy; can you tell me what camera acquisition settings are typically used in NHST?
1. Collimator
2. Matrix Size
3. Energy Window
- LEGP
- 526x1024
- γ-emission: 140.5 keV photopeak;
Window settings at 141 keV with 20 keV width
Can you tell me what DaTscan means?
DaT stands for dopamine active transporter.
Dopamine is a chemical which is important in areas of the brain that help control movement
What is the clinical need of a DaTSCAN?
It is used to detect the loss of nerve cells in an area of the brain called the STRIATUM, specifically the cells that release dopamine, a chemical messenger.
Referred for indications of:
1. Parkinson’s Disease
2. Lewly body dementia
With regards to a DaTSCAN; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- I-123
- IOFLUPANE
- 185 MBq
What is the mechanism of physiological uptake in a DaTSCAN?
The radio-ligand carries the γ-emitting radionuclide to the receptor of interest.
The DaTscan targets dopamine transporters to detect loss of functional dopaminergic neuron terminals in the STRIATUM
To PREVENT UNHELPFUL UPTAKE in the thyroid, the patient is provided with POTTASSIUM IODIDE CAPSULES;
- The day before the scan
- The same day before the scan
- The day following their scan
With regards to a DaTscan; can you tell me what camera acquisition settings are typically used in NHST?
1. Collimator
2. Matrix Size
3. Energy Window
- LEHR
- 128x128
- Since it is SPECT imaging, requires 2 acquisition windows, for photopeak and for scatter window:
Emission Window:
γ-emission: 159 keV photopeak;
Window settings at 159 keV with 20 keV width
Scatter Window:
Window settings at 130 keV with 20 keV width
What is the clinical need of a Bone Scan?
A bone scan examines the SKELETON in the diagnosis of;
- Metastatic disease.
- Metabolic disease, or
- Bone pain of UNKNOWN ORIGIN
With regards to a Bone Scan; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- Tc-99m
- PHOSPHONATES
- 600 MBq
What is the mechanism of physiological uptake in a Bone Scan?
Phosphonates are a CALCIUM ANALOGUE where uptake is dependant on OSTEOBLAST and OSTEOCLASTIC activity
Increased activity is a marker for OSTEOBLASTIC ACTIVITY
Uptake is controlled by;
1. Blood flow
2. Extraction efficiency
With regards to a Bone Scan; can you tell me what camera acquisition settings are typically used in NHST?
1. Collimator
2. Matrix Size
3. Energy Window
- LEHR
- 256x1024
- γ-emission: 140.5 keV photopeak;
Window settings at 141 keV with 20 keV width
NB: Procedure is performed in two parts.
1. Imaging of blood pool immediately after administration
2. Static bone scan 2-3 hours later
What is the clinical need of a Renography (MAG3) scan?
A MAG3 scan gives QUALITATIVE information on the FUNCTION of the kidneys, and can demonstrate evidence of RENAL TRACT OBSTRUCTION
QUANTITATIVE assessment of RELATIVE renal function possible
- Assesses DRAINAGE
NB:
If clinician is SPECIFICALLY INTERESTED IN DIFFERENTIAL FUNCTION then DMSA should be recommended over MAG3 (MAG3 is posterior only and calculated at 2-3 mins when curves are rising and are noisy)
With regards to a MAG3 Renography Scan; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- Tc-99m
- MAG3
- 100 MBq
What is the mechanism of physiological uptake in a MAG3 Renography Scan?
The MAG3-Tc99m tracer is EXCRETED through the RENAL TUBULES so demonstrates FUNCTION and DRAINAGE
With regards to a MAG3 Renography Scan; can you tell me what camera acquisition settings are typically used in NHST?
1. Collimator
2. Matrix Size
3. Energy Window
- LEGP
- 128x128
- γ-emission: 140.5 keV photopeak;
Window settings at 141 keV with 20 keV width
What is the clinical need of a static kidney scan (DMSA(III))?
A DMSA(III) scan looks at STRUCTURE and SIZE of the kidneys
Assesses what FRACTION of the TOTAL FUNCTION each kidney provides
Establishes any anatomical variations or presence of SCARRING in the kidney
NB:
If clinician is SPECIFICALLY INTERESTED IN DIFFERENTIAL FUNCTION then DMSA should be recommended over MAG3 (MAG3 is posterior only and calculated at 2-3 mins when curves are rising and are noisy)
With regards to a static kidney scan Scan; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- Tc-99m
- DMAS(III)
- 80 MBq
What is the mechanism of physiological uptake in a static kidney scan (DMSA(III))?
DMSA(III)-Tc99m binds to METALLO-PROTEINS in the CORTEX so provides HIGH-RESOLUTION imaging of the FUNCTIONAL ANATOMY
With regards to a static kidney scan (DMSA(III)); can you tell me what camera acquisition settings are typically used in NHST?
1. Collimator
2. Matrix Size
3. Energy Window
- LEHR
- 256x256
- γ-emission: 140.5 keV photopeak;
Window settings at 141 keV with 20 keV width
How would you process a a static kidney scan (DMSA(III))?
For quantification, the GEOMETRIC MEAN MUST BE CALCULATED using BACKGROUND CORRECTED COUNTS for the posterior and anterior views
- Draw ROIs around L & R kidneys as well as background ROIs adjacent to the kidneys
Differential function can be calculated from these mean counts.
LKF(%) = (LKGM/LKGM + RKGM)*100
What is the clinical need of a Parathyroid scan?
To identify and localise solitary/multiple PARATHYROID ADENOMAS
- Benign growths that appear on one or more of your parathyroid glands
With regards to a Parathyroid scan; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- Administration of two radionuclides:
a. I-123 (Thyroid specific radionuclide)
b. Tc-99m (Non-specific uptake) - Two pharmaceuticals that are radionuclide specific:
a. Iodide
b. Sestamibi - a. 20 MBq
b. 750 MBq
What is the mechanism of physiological uptake in a Parathyroid scan?
I-123 is tissue specific and up took by the THYROID ONLY
Sestamibi is taken up by cells with HIGH CONCENTRATION of MITOCHONDRIA (Metabolically active) and IS NOT tissue specific
- lipophilic cationic radiotracer
With regards to a Parathyroid scan; can you tell me what camera acquisition settings are typically used in NHST?
1. Collimator
2. Matrix Size
3. Energy Window
- LEHR (Discovery)
On Symbia, would use Pinhole & LEAP - 128x128
- Two radiotracers, and SPECT imaging so need two emission windows and a scatter window
Tc-99m
γ-emission: 140.5 keV photopeak;
Window settings at 141 keV with 20 keV width
Scatter window at 115 KeV with 10 keV width
I-123
γ-emission: 159 photopeak;
Window settings at 159 keV with 10 keV width
What is the clinical need of a lung perfusion scan?
Shows BLOOD FLOW to the lungs
Typically looking for indications for PULMONARY EMBOLISM (PE)
With regards to a Lung perfusion scan; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- Tc-99m
- Macro-aggregated albumin (MAA)
- 100 MBq
- 60 MBq for pregnant patients (‘Half’-dose)
What is the mechanism of physiological uptake in a lung perfusion scan?
> 90% of particles are TRAPPED in LUNG APILLARIES during FIRST PASS
It localizes by the mechanism of CAPILLARY BLOCKADE
With regards to an MPS scan; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- LEHR
- 128x128
- γ-emission: 140.5 keV photopeak;
Window settings at 141 keV with 20 keV width
What is the clinical need for a cerebral blood flow imaging scan (HMPAO)?
Looks at regional CEREBRAL BLOOD FLOW
Given for indications of:
1. Alzheimers
2. Vascular Dementia
3. Stroke
With regards to a cerebral blood flow Brain scan; can you tell me:
1. What radionuclide is used?
2. What pharmaceutical is used?
3. What is the LDRL in NHST for the examination?
- Tc-99m
- HMPAO (Exametazine - manufacturer label for HMPAO used in NHST)
- 500 MBq
What is the mechanism of physiological uptake in a cerebral blood flow Brain scan (HMPAO)?
HMPAO-Tc99m crosses the blood brain barrier and so can show CEREBRAL PERFUSION
Once across the blood brain barrier, it enters the NEURON and becomes a POLAR, HYDROPHILIC molecule TRAPPED inside the cell)
With regards to a HMPAO Brain scan; can you tell me what camera acquisition settings are typically used in NHST?
1. Collimator
2. Matrix Size
3. Energy Window
- LEHR
- 128x128
- SPECT imaging so need emission window and a scatter window
Tc-99m
γ-emission: 140.5 keV photopeak;
Window settings at 141 keV with 20 keV width
Scatter window at 120 KeV with 10 keV width
Cardiac Imaging Artefacts: What would you suggest if the patient had a ‘Hot Spleen’
Its important that all the signal is coming from the heart
If the patient has a ‘HOT SPLEEN’ you may need to:
1. Up the counts
2. Move the camera so the spleen is outside the FOV
IQ-SPECT is common in MPS clinical cardiology scans, can you describe IQ-SPECT briefly?
IQ-SPECT uses VRIABLY FOCUSSED CONVERGING collimators
Variable geometry heads target on a FIXED VOLUME which is defined by the user
Accelerated reconstruction including scatter and resolution recovery
40% increase in counts compared to standard scan for the same amount of time
- Though reconstruction is more complex
Discuss briefly common attenuation artefacts in clinical cardiology
Artefacts in cardiology may lead to over reporting
Typical sources of attenuation artefacts differ for men and women
(M): Diaphragm attenuation
- Causes fixed INFERIOR DEFECT
(F): Breast attenuation
- Causes fixed ANTERIOR DEFECT
Reports of MPS scans follow a 4 tier risk reporting structure. Summarise this.
- Normal
- Low Risk (<3% ischemic myocardium) - Fixed (infarct) defect
- Medium Risk (3-9%) - Small ISCHAEMIC DEFECT/mixed infarct/ischemia
- High Risk (>9%) - Large ISCHAEMIA
NB: Ischemia is a condition in which blood flow (and thus oxygen) is restricted or reduced in a part of the body
How is attenuation correction achieved? You can use clinical cardiology as a specific example. Discuss possible disadvantages for this
Attenuation correction can be achieve by:
- Transmission sources
- Disadv: Sources need to be replaced regularly
- SPECT-CT
- CT required energy correction - Gated SPECT for inferior defect from diaphragm
- Breast binding for anterior defect in women
Disadvantages of attenuation correction:
Wash out features due to GUT UPTALE dominating after attenuation correction
- Care must be taken not to introduce more artefacts than are removed
Why are patients sometimes imaged twice twice for MPS? - Stress/Rest
Protocol is to compare for MISMATCH between stress and rest tests
Defect comparison in MPS:
Perfusion defect on stress/normal on rest = ISCHEMIA
Perfusion defect on BOTH = Infarct
What would increased/decreased uptake of Tc-MDP (Bone scan) indicate?
Increased Uptake: Osteoblastic activity is present
Decreased uptake: Evidence of Purelytic lesion
What is a SUPERSCAN?
Diffuse METASTASES throughout the skeleton
Virtually all tracer is absorbed in bone with little to no urinary or tissue uptake
Can be caused by metabolic bone disease
