Hi Neha
I will be giving a basic outline on how to approach the examination of the axial projection of the heart (Notes Scales and Music) and the first slide below gives an approximation of the sizes –
- First Image
- top left image
- sizes to remember (approximate +/- 1cms) Mantra 4,5,4,5
- top right image –
- at the level of the mitral valve the atria are about the same size and about 1/3 the size of their respective ventricles
- bottom left
- at this level the overall volume of the RV is about 2/3 the size of the LV
- bottom right
- In diastole (if you can appreciate open mitral valve) thickness is up to 1.2 cms – 1.4 is upper limits normal
- top left image
- Next series of images – as you start from the top of the heart on the axial image and follow the order so you can remember mantra (4,5,4,5 – of the approx sizes of the structures)
- Where to measure LA –
- Look for the aorta – and then look up and down till you find max dimension
- Where to measure RA
- See where the approx position of TV and the from posterior wall to the TV
- Where to measure RV and LV cavity dimensions
- – at at the level of the A-V valves or mid septum by the moderator band
- LV wall thickness
- Same level
- Overall Volume Assessment
- At the same level Rule of thirds for volume
- MPA and Ao
- At bifurcation of MPA
- Systole and diastole to look assess EF
- On gated images – compare peak systole to diastole using eyeball and mitral or tricuspid valve and use rule of thirds
- Where to measure LA –
Summary
NOTES SCALES AND MUSIC
At the level of the mitral valve which is also about mid septum, the chambers are relatively all best visualised. This is a place where approximate size can be evaluated
LA +/- 4cms (post wall to MV)
The aorta is a reference structure and is usually about the same size or smaller. In this instance it is 3.5cms.
RA +/- 5cms (post wall to TV)
(normal up to about 5cms)
RV +/- 4cms (transverse) not >6
NORMAL LINEAR DIMENSION OF THE RIGHT VENTRICULAR CAVITY ON A GATED CT SCAN
(normal up to about 4-5cms)
LV +/- 5cms (transverse) not >6
NORMAL LINEAR DIMENSION OF THE LEFT VENTRICULAR CAVITY ON A GATED CT SCAN
(normal up to about 5-5.5cms)
LV Thickness in Mid Septal Region
Buzz
1.2
Axial images through the left ventricle (LV) in mid septal region at the level of the opened mitral valve (early diastole) shows a septal thickness of 8.8mms and free wall thickness of 9mms (normal up to about 12mms)
Ashley Davidoff MD
Volume Assessment of the Cavities (Rule of Thirds)
Buzz
RA = LA = 1/3 ventricles
RV = 2/3 LV
Axial images through the 4 chambers at the level of the A-V valves during diastole (mitral valve open) enables an approximate volume evaluation of the chambers. The atria are approximately the same volumes, and are about 1/3 the volume of the ventricles. The right ventricle (RV) is about 2/3 the volume of the left ventricle (LV)
Ashley Davidoff MD
PA/Ao
Buzz
3/3.5
Axial images through the main pulmonary artery (MPA) and proximal ascending aorta (Ao) shows a MPA measurement of 2.5cms (normal up to 3cms) and referenced to the aorta usually about the same size or
Ashley Davidoff MD
Volumes in Systole and Diastole
19 year old male with syncope with normal MRI.
Images a and b show peak systole with volumes of the LV and RV about 1/3 the volume of their respective ventricles when in diastole. This leaves 2/3 of volume has been ejected implying that the ejection fraction is 66%
Ashley Davidoff MD
Summary
At the level of the mitral valve which is also about mid septum, the chambers are relatively all best visualised. This is a place where approximate size can be evaluated
Ashley Davidoff MD
Next James McLoughlin Assessment of LV Mass