A multiple sclerosis, deep vein thrombosis, and/or pulmonary embolism therapeutic system comprising: a therapy delivery catheter (6, 52, 68, 82, 96) including an intravascular imaging component (14, 22) at the distal end of the catheter, wherein the intravascular imaging component includes at least one of an intravascular ultrasound (IVUS) component and an optical coherence tomography component, a therapeutic delivery component (64, 80, 94, 108), wherein the intravascular imaging component is configured to image a vein or pulmonary vessel, and wherein the therapeutic delivery component is configured to apply a treatment to a lesion of the vein or pulmonary vessel; wherein the catheter has a catheter body (54, 70, 84, 98) with a distal end (56, 72, 86, 100), a proximal end (60, 74, 88, 102), a central lumen (62, 76, 90, 104) extending along the catheter body and through which a guide wire may be passed from the proximal end to the distal end, and a balloon lumen (66, 110) extending along the catheter body to the therapeutic delivery component, wherein the therapeutic delivery component includes a balloon (64, 108) being coated with or exuding a therapeutic agent and/or being a cutting or scoring balloon; a blood pressure measuring device; and a computing device configured to identify indications of at least one of multiple sclerosis, deep vein thrombosis, and pulmonary embolism by performing the steps of: identifying at least one venous outflow obstruction site in the vein or pulmonary vessel; assessing the nature of the at least one obstruction site to determine whether the at least one obstruction site causes significant narrowing of the vein or pulmonary vessel by using IVUS imaging, OCT imaging or both IVUS and OCT imaging, determining a pressure gradient across the at least one obstruction site as compared to the superior vena cava based on blood pressure measured by the blood pressure measuring device, wherein obstruction sites causing significant narrowing of the vein or pulmonary vessel are identified for treatment with the therapeutic delivery component; and applying a desired therapy with said therapeutic delivery component to treat the at least one obstruction site. a therapy delivery catheter (6, 52, 68, 82, 96) including an intravascular imaging component (14, 22) at the distal end of the catheter, wherein the intravascular imaging component includes at least one of an intravascular ultrasound (IVUS) component and an optical coherence tomography component, a therapeutic delivery component (64, 80, 94, 108), wherein the intravascular imaging component is configured to image a vein or pulmonary vessel, and wherein the therapeutic delivery component is configured to apply a treatment to a lesion of the vein or pulmonary vessel; wherein the catheter has a catheter body (54, 70, 84, 98) with a distal end (56, 72, 86, 100), a proximal end (60, 74, 88, 102), a central lumen (62, 76, 90, 104) extending along the catheter body and through which a guide wire may be passed from the proximal end to the distal end, and a balloon lumen (66, 110) extending along the catheter body to the therapeutic delivery component, wherein the therapeutic delivery component includes a balloon (64, 108) being coated with or exuding a therapeutic agent and/or being a cutting or scoring balloon; a blood pressure measuring device; and a computing device configured to identify indications of at least one of multiple sclerosis, deep vein thrombosis, and pulmonary embolism by performing the steps of: identifying at least one venous outflow obstruction site in the vein or pulmonary vessel; assessing the nature of the at least one obstruction site to determine whether the at least one obstruction site causes significant narrowing of the vein or pulmonary vessel by using IVUS imaging, OCT imaging or both IVUS and OCT imaging, determining a pressure gradient across the at least one obstruction site as compared to the superior vena cava based on blood pressure measured by the blood pressure measuring device, wherein obstruction sites causing significant narrowing of the vein or pulmonary vessel are identified for treatment with the therapeutic delivery component; and applying a desired therapy with said therapeutic delivery component to treat the at least one obstruction site. identifying at least one venous outflow obstruction site in the vein or pulmonary vessel; assessing the nature of the at least one obstruction site to determine whether the at least one obstruction site causes significant narrowing of the vein or pulmonary vessel by using IVUS imaging, OCT imaging or both IVUS and OCT imaging, determining a pressure gradient across the at least one obstruction site as compared to the superior vena cava based on blood pressure measured by the blood pressure measuring device, wherein obstruction sites causing significant narrowing of the vein or pulmonary vessel are identified for treatment with the therapeutic delivery component; and applying a desired therapy with said therapeutic delivery component to treat the at least one obstruction site.