More recently, 4-D flow has been used to assess the MPA and detect the hemodynamic alterations that occur with PH: decreased wall shear stress, increased tricuspid regurgitation velocity, and abnormal vortex blood flow pattern within the MPA that is associated with early-onset systolic retrograde flow [65,72-74]. MRA Chest Pulmonary MR angiography (MRA) shows morphologic changes of PH that are also depicted by MRI heart and CT/CTPA: PA enlargement, MPA to adjacent ascending aorta ratio >1, RV enlargement and hypertrophy, straightening of the interventricular septum, and pericardial thickening and effusion [61,65,66]. MRA has lower sensitivity for the detection of acute and chronic pulmonary embolism compared with CTPA [61]. There are no data to support the use of MRA chest alone as a first-line test for suspected PH; however, the combination of MRA Catheterization Right Heart RHC is an invasive procedure that defines cardiopulmonary hemodynamics and is performed after all noninvasive examinations have been completed to confirm the diagnosis of PH before initiating treatment per current guidelines [24]. RHC directly measures the PAP to confirm the diagnosis of PH as well as the PAWP and cardiac function (thermodilution or Fick method), which are both necessary to determine PVR. The mean PAP, PAWP, and PVR values obtained from RHC are used to classify PH into precapillary PH, isolated postcapillary pH, or combined pre- and postcapillary PH [78-80]. Vasoreactivity testing of the pulmonary circulation may also be performed at the time of RHC in selected patients with IPAH, heritable PAH, and drug-induced PAH to determine candidacy for calcium channel blocker treatment [79]. RHC has morbidity and mortality rates of 1.1% and 0.055%, respectively [81]. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list.
Suspected Pulmonary Hypertension. More recently, 4-D flow has been used to assess the MPA and detect the hemodynamic alterations that occur with PH: decreased wall shear stress, increased tricuspid regurgitation velocity, and abnormal vortex blood flow pattern within the MPA that is associated with early-onset systolic retrograde flow [65,72-74]. MRA Chest Pulmonary MR angiography (MRA) shows morphologic changes of PH that are also depicted by MRI heart and CT/CTPA: PA enlargement, MPA to adjacent ascending aorta ratio >1, RV enlargement and hypertrophy, straightening of the interventricular septum, and pericardial thickening and effusion [61,65,66]. MRA has lower sensitivity for the detection of acute and chronic pulmonary embolism compared with CTPA [61]. There are no data to support the use of MRA chest alone as a first-line test for suspected PH; however, the combination of MRA Catheterization Right Heart RHC is an invasive procedure that defines cardiopulmonary hemodynamics and is performed after all noninvasive examinations have been completed to confirm the diagnosis of PH before initiating treatment per current guidelines [24]. RHC directly measures the PAP to confirm the diagnosis of PH as well as the PAWP and cardiac function (thermodilution or Fick method), which are both necessary to determine PVR. The mean PAP, PAWP, and PVR values obtained from RHC are used to classify PH into precapillary PH, isolated postcapillary pH, or combined pre- and postcapillary PH [78-80]. Vasoreactivity testing of the pulmonary circulation may also be performed at the time of RHC in selected patients with IPAH, heritable PAH, and drug-induced PAH to determine candidacy for calcium channel blocker treatment [79]. RHC has morbidity and mortality rates of 1.1% and 0.055%, respectively [81]. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list.