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Longitudinal ultrasound image of the popliteal artery and vein with colour flow mapping. Blue colour indicates flow away from the transducer and red colour indicates flow towards the transducer. The light green quadrilateral is the colour Doppler sample volume. The vein appears larger than the artery in the two dimensional ultrasound image.

Femoral artery Doppler pattern
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Doppler ultrasound tracing from the left femoral artery is seen the lower panel. The tall upward component is the predominant systolic flow. The graduation at the right end is the velocity in cm/sec. The upper panel shows the longitudinal image of the femoral artery seen as a dark longitudinal shadow in the middle of the image. The imaging line with cursor within the lumen of the femoral artery is also seen in the upper panel.

X-ray of knee joint showing femur above and tibia and fibula below with knee joint. The epiphyseal plates are seen as transluscent lines near the end of the the bones (yellow arrows). The region beyond the the ephiphyseal plate and adjoining the joint is the epiphysis. The densely calcified outer region of the shaft is known as the cortex and the inner region which holds the bone marrow is known as medulla (blue arrows).

Normal X-ray chest PA view demonstrating  cardiovascular structures. RPA: right pulmonary artery; LPA: left pulmonary artery; MPA: main pulmonary artery. Right heart border is formed by the right atrium. Linear shadow above the right atrial contour is the superior vena cava along the right para spinal region. Left heart border is formed by the main pulmonary artery segment above and the left ventricle below. The mild depression in between is the region of the left atrial appendage. Apex is formed by the left ventricle in the normal chest X-ray. The left …

Plain X-ray abdomen showing multiple air fluid levels (yellow arrows) in a case of subacute intestinal obstruction.

PQRST in normal ECG

 The waves and intervals in a normal electrocardiogram (ECG) are illustrated above. P wave is due to atrial depolarisation. QRS is the ventricular depolarisation and T wave represents ventricular repolarisation. Atrial repolarisation is called Ta wave. Ta wave is not visible because it is shallow and superimposed on the PR segment, QRS and part of the ST segment. STD: standardisation pulse, a square wave of 1 mV amplitude, giving 10 mm vertical amplitude in usual ECG. 1 mm on X-axis represents 40 msec as the ECG is …