Radiology 1, 2 3 Flashcards
How are x-rays formed?
The cathode directs a stream of electrons into a vacuum, which collects the electrons. When the electrons hit the anode, about 99% of the resulting energy is emitted as heat with the other 1% being emitted as x-rays.
How many mSv does an x-ray emit?How many mSv does a chest CT emit?
0.0210
What causes blunting of the costophrenic angle?
Usually a pleural effusion but it can also be caused by lung disease in the region of the costophrenic angle or hyper expansion
What is situs inversus?
an uncommon condition in which the heart and other organs of the body are transposed through the sagittal plane to lie on the opposite (left or right) side from the usual.
What is the cardiothoracic ratio (CTR)?what is an abnormal ratio?
Cardiac width: thoracic widthA CTR of greater than 1;2 is abnormal (50%)
What can exaggerate the size of the heart?
if the patient doesn’t breath fully
What kind of congenital malformation can be seen on the bronchial tree on imaging?
Hilar bronchogenic cysts
What lobes of the lung can be mainly seen on frontal radiography?
Right:RULRMLLeft:LULLingula
What lung lobes are seen in posterior radiography?
RLLLLL
What type of fissure does both lungs have?
ObliqueRight lung also has a horizontal fissure
What allows the different types of tissue present on a CT scan to be compared?Unit?
Each tissue has distinct densitiesHounsefield unit
What happens to a silhouette on imaging when you have 2 tissues of the same density together?
You lose the sillhouette
What are 2 other names for a mycetoma?What is this?
AspergillomaFungus ballA clump of old which exists in a body cavity caused by fungi of the genus apergillus
What causes the appearance of lots of different dots in the lungs?
Miliary Tuberculosis (TB) - widespread dissemination of Mycobacterium tuberculosis via hematogenous spread
What lung disease is huge hillier lymph nodes a sign of?
Sarcoidosis
What is consolidation?
radiological sign that refers to non-specific air-space opacification on a chest radiograph or chest CT
What 2 questions regarding a PTE should be asked before a D-dimer is measured?
Is another diagnosis unlikely?Is there a major risk factor?Measure D-dimer if only 1 of the above answers is raised
What are the major risk factors for a PTE according to radiology form? (6)
Recent immobilityPregnancy/ post partumMajor medical illnessMajor surgeryPrevious VTELower limb trauma or surgery
what 3 questions should be considered when thinking about referring for a CTPA or V/Q scan (PTE)?Results needed to get a scan
Is another diagnosis unlikely?Is there a major risk factor?Is the D-dimer raised? (only measure if only 1 of the above answers is YES)CTPA or V/Q scan will only be done if 2 or more are YESIf
What does CTPA stand for?
CT pulmonary angiography
What is a V/Q scan?
Involves 2 types of radioisotope scans - patient inhales radioisotope gas and has radioisotopes infected into their veins - scan compares ventilation and blood flow in the lungs
What imaging is indicated for a PTE when CXR is normal?
V/Q scan
What imaging is indicated for PTE when radiation has tO be avoided/ left swollen?
Consider US leg for DVT
What imaging is indicated for PTE if CXR abnormal/ massive PE suspected?
CTPA
What is the usual isotope used for V/Q scan?
Tetnisium
If the patient has a PTE, what will a V/Q scan show?
Normal ventilation with abnormal perfusion
What are the 4 factors you have to look at to assess if a lung x-ray is technically adequate?
PenetrationInspirationRotationAngulation
How to check penetration?
You should be able to see the thoracic spine through the heart
How to check inspiration?
About 10 posterior ribs visible in an excellent inspiration, although in many hospitals 9 is adequate
How to check rotation?
Spinal process of the vertebral body is equidistant from the medial ends of each clavicle
How to check angulation?
A film which is angled up towards the head (apical lordotic) will have an unusually shaped heart and the sharp border of the left hemidiaphragm will be absent
Hamartoma?
a benign tumorlike nodule composed of an overgrowth of mature cells and tissues normally present in the affected part, but often with one element predominating (benign)
Are most lung masses benign or malignant?
Malignant
Are central or peripheral lung tumours likely to be more commonly asymptomatic?
Peripheral
what is lipoid pneumonia?
a specific form of lung inflammation (pneumonia) that develops when lipids enter the bronchial tree
Does scars form old TB predispose to lung cancer?
no
What are synchronous tumours?
Histologically distinct simultaneously deteted malignancies
What are metachronous tumours?
Not synchronous; multiple separate occurrences, such as multiple primary cancers developing at intervals.
What is bilateral calcified pleural plaque a marker of?
Asbestos exposure
What is asbestosis?
a lung disease resulting from the inhalation of asbestos particles, marked by severe fibrosis and a high risk of mesothelioma (cancer of the pleura).
What does HRCT stand for?
High resolution pulmonary fibrosis
What are peripheral tumours?
Tumours arising beyond the hilum
What are central tumours?
Tumours arising at or close to the hilum
Are peripheral tumours that are less than 1cm diameter visible on chest x-ray?
Rarely
Signs of a central tumour?
Hilar enlargementDistal collapse/ consolidation(not as easy to spot as a distal tumour as hidden by the mediastinum)
What is the international staging mechanism for lung cancer?
TNM
In terms of staging a tumour, what is contrast enhanced CT very good for? (3)
Assessing tumour sizeShowing intracranial metastasesGuiding a biopsy of peripheral lesions
What is a PET scan very good for in terms of staging? (3)
Detecting:Nodal metastasesDistant metastases (not brain)Delineating tumour in an area of collapse
Is soft tissue differentiation better with MRI or CT?
MRI
Is spatial resolution better with MRI or CT?
CT
In the staging of lung cancer, what does M1a mean?
there are tumours in both lungs or fluid around the lung or heart that contains cancer cells
In the staging of lung cancer, what does M1b mean?
there are lung cancer cells in distant parts of the body, such as the liver or bones
What is adenopathy?
Another name for lymphadenopathy
In what type of lung cancer is mediastinal adenopathy often marked?
Small cell lung cancer - lottos nodal metastases
What is the main treatment for small cell lung cancer?
Chemotherapy (as it often spreads very quickly)
What is pulmonary lymphangitis carcinomatosis?
Tumour spread through the lymphatics of the lung
What is a complication of CT guided biopsy?
Pneumothorax
What is an US good for imaging?
Pleural effusionSubphrenic collectionMovement of diaphragmUS guided drainage
What is a teratoma?
A tumour composed of tissues not normally present at the site (typically in the gonads)
What is radiation fibrosis?
abnormal production of the protein, fibrin, which accumulates in and damages the radiated tissue.
What is thoracoplasty?
the operation removing selected portions of the ribs to collapse part of the underlying lung or an abnormal pleural space, usually in the treatment of tuberculosis.
Why are the shoulders braced forward when taking a CXR?
To prevent the scapulae from obscuring the lungs
What does a PA radiograph mean?
The x-rays pass from posterior to anterior
When is an “AP radiograph” taken?
In patients who cannot stand
Why are AP radiographs not as good as PA radiographs?
The heart shadow is magnified so heart size can bot be accurately assessedThe scapulae overlie and partly obscure the lungsIt can be difficult for the patient to take an adequate inspiration
How much higher is the right diaphragm above the left diaphragm?
1.5cm
What colour should the retrosternal and retrocardiac spaces be on a lateral CXR?
Dark
CXR silhouette sign?
Loss of a borders edge may signify pathology
What are the names of the lung zones?
Each lung has an upper, middle and lower lobe
What could cause the left heart border to become obscured?
Infection of lingula
What causes a lobar collapse?
Obstruction of a lobar bronchus e/g/ tumours, food, mucus impaction
What lobar collapse causes displaced left oblique fissure and an obscured medial part of the left hemidiaphragm?
Left lower lobe collapse
What lobar collapse causes a displaced right horizontal fissure with a densnes superiorly to the fissure?
Right upper lobe collapse
What lobar collapse causes the left oblique fissure to be pulled anteriorly and obscures the left heart border?
Left upper lobe collapse
When is the pleural cavity visible on chest radiographs?
When it is filled with fluid (pleural effusion) or air (pneumothorax)
Where can dense pleural fluid be present on an erect CXR?
Seen to collect at the lung bases or tracking into the oblique and horizontal fissures
