Prunning of Pulmonary aeries is seen in:

A i.e. Pulmonary hypeension Pulmonary aerial hypeension is characterized by pruning of peripheral pulmonary aeriesQ (i.e. dispropoionate increase in caliber of fibrous central aeries from sustained increase in PBF with a decrease in caliber of small muscular/peripheral aeries). Pulmonary (Aerial) Hypeension (PAH) It is defined as an elevation in mean pulmonary aerial pressure above 30mmHg during execise and above 25mmHg at rest in systole. An increase in PAH most commonly occurs as a result of intrinsic lung disease, which results in an increae in pulmonary vascular resistance and subsequent increase in PA pressure. PAP can also increase as a result of an increase in pulmonary venous pressure (which may be d/t impaired left ventricle function or obstruction to left sided cardiac flow eg MS etc). So radiological features may be slightly different depending on cause i.e. pulmonary aerial or pulmonary venous hypeension. Radiological features of PAH include. Vascular Signs - Enlargement of central pulmonary aeries (main pulmonary aery & its branches down to the segmental level)Q and tapering of peripheral aerial branches (vessels beyond segmental level)-termed pripheral pruningQ are seen - Enlargement of central main pulmonary aery may be extremely large with complete infilling of pulmonary aery/ventricular concavity of left hea border on X-ray. - Widest diameter of main pulmonary aery (MPA) 29mm measured on transverse section (CT) at level of PA bifurcation has 90% sensitivity & specificity - Diameter ratio of MPA to ascending aoa (measured at same level) >1 i.e. diameter of MPA>AA has strong correlation in - Transverse diameter of right descending pulmonary aery at midpoint >17mm (Grainger); diamete of left and right pulmonary aery >16mm (Wolfgang); maximum diameter of descending branch of pulmonary aery (measured lcm medial & 1 cm lateral to hilar points) >16mm for males & >15mm for females (Sutton) - Pulmonary aeries with in lungs are enlarged but there is rapid tapering of vessels (beyond segmental level) as they run towards the periphery. The impoant feature is discrepancy between central and peripheral vessel size, central pulmonary aeries being large or near normal sometimes and peripheral aeries dispropoionately small (pruning or tapering). - Vascular complications include sub pleural pulmonary infarct, dissection & calcified plaques of central pulmonary aeries (pathognomic, a feature not seen in nonhypeensive pulmonary aeries; is often curvilinear & egg shape calcificaiton mimicking enlarged lymph nodes, from which it is differentiated by absence of lobulation and presence of smooth border). - Pulmonary veins are small in pre capillary pulmonary hypeension whereas enlarged in post capillary causes. Mediastinal & Cardiac Signs - Cardiac enlargement (right hea i.e. RA and RV enlargement & hyperophy)Q demonstrating a large, triangular hea. - Mild pericardial thickening & effusion. - Dilatation of IVC, coronary sinus & SVC (On MRI/CT) Lung Parenchymal Signs - Mosaic perfusion without dilatation of bronchi (increase in vessel diameter in areas of hyper attenuation & tapering of peripheral vessels in areas of hypo attenuation)