cardiovascular imaging Flashcards
1
Q
imaging techniques
A
- x-ray methods:
- catheter or direct puncture angiography: invasive
- radiography, fluoroscopy (non-invasive) - ultrasound - Doppler methods (non-invasive)
- CT, CT-angiography (non-invasive)
- MR, MR-angiography (non-invasive)
2
Q
radiography
A
- digital is preferred over analog
- summation images: high spatial resolution, low contrast resolution
- bi-directional (PA, lateral) CXR -> heart + great vessels are in the mediastinal shadow, well contoured by air-containing lungs
- information on: heart size, dilation + course of mediastinal vessels, calliber of pulmonary vessels, cardiac + vessel wall calcification, inserted IV lines, devices, pacemakers
- fluoroscopy: pulsation of heart + vessels
3
Q
signs of congestive heart failure
A
- cephalization of pulmonary vasculature -> pulmonary venous pressure increases
- Kerley lines: interlobular septal thickening - interstitial edema
- diffuse alveolar edema: perihilar distribution, butterfly or bat-wing pattern, coalescing fluffy opacities, air-bronchogram
- pleural effusion
- enlarged heart (+/-)
4
Q
ultrasonography
A
- fluids: hypo- or an-echoic -> blood-filled vessels + heart chambers are dark on 2D ultrasound images
- real time imaging (echocardiography)
- high resolution imaging of vessel wall & lumen: for superficial vessels, plaque analysis
- bones & air are not penetrated by US. “Acoustic window” is needed
- Doppler techniques: accurate velocity measurements - haemodynamic analysis. Color Doppler - flow map.
- 2D ultrasound images + spectrum Doppler = duplex ultrasound
5
Q
main indications of duplex sonography
A
- cerebrovascular disease (carotid stenosis, transcranial Doppler)
- obliterative arterial disease of extremities (atherosclerotic chronic disease, acute embolic occlusion)
- deep venous thrombosis of the extremities
- abdominal vessels (AAA - aneurysm of the abdominal aorta, renal artery stenosis, abdominal angina - mesenteric artery stenosis, portal HTN)
- soft tissue vascularisation (eg tumors)
- post-surgical conditions - complications
6
Q
significant arterial stenosis
A
- vessel wall irregularity
- plaques causing stenosis
- > 50% stenosis - quantification is more accurate on haemodynamic basis
- elevated end-systolic & end-diastolic peak velocity
- sign of turbulence - filling of :systolic window”
7
Q
patent deep venous trunk
A
- echo-free compressible lumen
- spontaneous flow with preserved respiratory fluctuations
- augmentable with manoeuvres
8
Q
acute thrombosis
A
- dilated non-compressible lumen
- lack of spontaneous flow
- restricted augmentation
- intraluminal echoes +/-
9
Q
chronic thrombosis
A
- difficult diagnosis
- deliniation of lumen is less clear, irregular “braid-like” collaterals
- variable spontaneous flow, restricted respiratory fluctuation, reflux augmentable
10
Q
advanced CT & MRI techniques in cardiovascular imaging
A
- spiral CT-angiography
- ECG-gated cardio-CT
- MR-angiography
- ECG-triggered cardio-MR
11
Q
vascular imaging by CT
A
- non-contrast CT: pathologic mural calcification, coronary Ca scoring
- contrasted-enhanced CT -> “conventional” technique: aorta (d >/= 1cm)
- spiral CT-angiography: single detector row spiral CT ( branches of aorta, d >/= 2-3 mm), multidetector row spiral CT (peripheral vessels, d >/= 1 mm)
12
Q
helical (spiral) CT angiography
A
- dynamic IV administration of contrast material
- scan-delay optimised for the selected circulation phase
- helical scanning with thin collimation during the first pass of contrast bolus
- post-processing of primary scan data: multiplanar and 3D reformatted images resembling DSA
13
Q
vascular imaging by CT - scanning parameters
A
- slice thickness as thin as possible (isotropic imaging): 4-16 slice CT: 1 - 1,25 mm / 16-256 slice CT: 0,5 - 1,25 mm
- multiphase examination if necessary: venous filling, vessel walls, perivascular tissues, parenchymal organs
- ECG-gating: coronary CTA, congenital anomalies, “triple rule-out” approach for acute chest pain
14
Q
vascular imaging by CT - contrast administration
A
- type: non-ionic, preferably low osmolality
- dose: MDCT: 1 - 1,5 cc/kgBW
- automatic injection: 2,5 - 5 cc/sec, second phase saline flush
- scan timing to achieve optimal “first pass” effect: empiric -> variable circulation times, bolus detecting program (bolus tracking) -> automatic detection of intravascular density elevation at arrival of contrast bolus
15
Q
MR angiography: without contrast - TOF (time-of-flight)
A
short repetition time results in the saturation of stationary tissues; signal is generated only by the unsaturated spins in the blood entering the examination plane (inflow effect)
application: intracranial arteries
16
Q
MR angiography: without contrast - PC (phase contrast)
A
flow (depending on its direction and velocity) changes the phase of precessing spins
- flow direction determination
- flow velocity determination
application: haemodynamic analysis
17
Q
MR angiography: with contrast material (CE-MRA)
A
sequences based on the marked T1 shortening effect of paramagnetic Gd
- dynamic IV administration of contrast material (Gd)
- scan-delay optimised for the selected circulation phase
- T1 weighted 3D gradient echo fast sequence during the first pass of contrast material
18
Q
CE-MRA post-processing
A
a. 2D reformatted images:
- multiplanar (MPR)
- curved (analog the course of vessels)
b. 3D reformatted images:
- maximun intensity projection (MIP)
- volume rendering (VR)
- shaded surface display (SSD)
c. semi-automatic analysis programs:
- automatic segmentation, “bone-removal”
- stenosis quantification based on diameter and/or cross-sectional area reduction measurement
- aneurysm sizing for stent-graft implantation
19
Q
CE-MRA evaluation
A
- primary slices: these contain all the information provided by the study. Any further processing may result in data loss
- MIP (maximum intensity projection): DSA-like demonstration of global vascular anatomy. “slab MIP” -> target volume, stenosis analysis
- MPR (multiplanar reconstruction), CR: stenosis, plaque analysis
- 3D volume rendering (VR), SSD: demonstration of complex anatomy of vessels / bones / parenchymal organs
20
Q
CT/MRA main indications: emergency conditions
A
- acute chest pain: acute aortic syndrome, acute pulmonary embolism, acute coronary syndrome
- acute abdominal pain: rupture or pending rupture of AAA, mesenterial ishcemia
- subarachnoid bleeding: aneurysm of the circle of Willis, vascular malformation
- traumatic injury of great vessels
- massive bleeding with haemodynamic instability: tracheo-bronchial, gastrointestinal, genito-urinary
21
Q
thoracoabdominal aorta - aneurysms
A
PRIMARY ASSESSMENT:
- diameter, length
- anatomy of proximal and distal necks
- origin of branches
- intraluminal thrombus
- vessel wall thickness, periaortic tissues (inflammation?)
- signs of imminent rupture
FOLLOW UP:
- growth
- d > 5,5 - 6 cm is indication for intervention
- postoperative follow-up: anastomoses, signs of pseudoaneurysm formation, early complications, late complications (aorto-duodenal fistula)
22
Q
aortic dissection - acute
A
- type: Stanford A or B?
- possible dissection variant
- intramural hematoma
- penetrating ulcer, circumscribed dissection
- anatomy of true + false lumen, diameter
- side branches (supraaortic, renal, splanchnic, iliac)
- origin from true or false lumen
- dissection affecting the aortic branch
- signs of stenosis, thrombosis, hypoperfusion
23
Q
aortic dissection - chronic
A
- progression of secondary aneurysm
- signs of imminent rupture
- side branches
24
Q
planning and follow-up of endovascular interventions
A
- sizing before stent-graft implantation:
- accurate diameters of proximal and distal vessel segments
- distance from proximal and distal branches, bifurcations - post-intervention follow-up:
- endoleak?
* type (source)
* degree, progression
25
Q
endovascular interventions: indications
A
- atherosclerotic obliterative arterial disease
- cerebrovascular disease
- renovascular hypertension
- mesenteric ischemia
- limb ischemia
- (ischemic heart disease)
26
Q
renal arteries - pathology
A
- renovascular hypertension:
- clinical suspicion of RAS with equivocal examination results (clinical data, US, nuclear medicine)
- after catheter angiography: complex anatomy
- AAA +/- RAS?
- assessment of the arterial supply of transplanted kidney
- post-operative / stent follow-up - renal artery aneurysm
- renal artery anomalies: lower polar artery causing ureteral stenosis?
27
Q
extremity arteries - pathology
A
- obliterative disease:
- for the selection of optimal treatment choice: CTA or MRA, instead of DSA -> able to map the whole extremity arterial tree
- special MRA technique with table stepping
- only MDCT enables the imaging of long segments (whole extremity) with reasonable contrast amount & x-ray exposure - femoro-popliteal aneurysms
- popliteal entrapment syndrome
- vascular injuries associated to pelvic and long bone fractures
28
Q
indications of CTA - MRA: pulmonary circulation
A
- acute pulmonary embolism:
- direct visualization of emboli filling the lumen completely or partially
- peripheral branches down to subsegmental level are adequately assessed
- IV contrast administration
- feasible in critically ill, non-cooperative patients as well
- DDX: ptx, pneumonia, tumor, etc - chronic pulmonary thrombo-embolic disease:
- clinical signs of pulmonary arterial HTN
- known embolic episode in clinical history
