M.NEDEVSKA

Practice pattern changes in diagnostic vascular medicine Imaging modalities of choice in vascular medicine have changed The advent of CE-CTA and CE-MRA – noninvasive alternatives excellent quality 3D images of the vascular tree avoiding the potential complications associated with invasive procedures Marked reduction of the conventional diagnostic angiography workload Extensive use of CT/MR

The aim of the presentation Brief overview of CTA and MRA for the diagnosis of peripheral vascular disease To depict advantages and limitations The particular modality of choice depends on many factors

Clinical applications  Evaluation of acute and chronic atherosclerotic steno-occlusive disease and its complications  Follow up of lower extremity arterial by-pass surgery  Recurrent symptoms following lower extremity angioplasty  Congenital anomalies  Traumatic and iatrogenic injures  Inflammatory conditions  Embolic phenomena  Aneurysmal changes

Catheter angiography DSA remains the diagnostic gold standard for detecting PVOD Can localize and quantify obstructive lesions with an accuracy exceeded only by IVUS Permits physiological evaluation by determining pressure gradients The ability to diagnose and treat disease in a single procedure In acute settings, where catheter-based intervention is likely to be indicated, direct reference to CAT Lab is the preferred option

Cost benefit ratio DSA/MRA/CTA Extensive debate – cost- benefit ratio To be really cost effective, any noninvasive method would have to supplant, not just to precede or supplement DSA DSA- recovery period lasting 4 hours or more, usually pts remain in the hospital overnight Complication - additional intervention or prolongation of hospital stay. This adds cost, morbidity and mortality

DSA- invasive technique Small, but definite risk of complications Rare fatal systemic reaction Contrast induced nephropathy (CIN) – elderly pts., diabetic, with impaired renal function Radiation exposure – pts with repeated examinations over the course of their disease Imperfect evaluation of outflow vessels, limited visualization of pedal vasculature, distal vessel beyond significant obstructive lesion

MR peripheral angiography Noninvasive and low risk, no radiation exposure High Sens and Spes for detecting PVOD Entire vascular system, including tibial and pedal arteries Routinely illustrate most information needed before treatment: General road map – runoff vessels, collaterals. Localization and extent of significant stenosis.

MRA from the past to the future Early sequences – protocols with 30 min of gradient time or more Modern technology (3T, parallel imaging, multi-channel coils, new sequences – time resolved MRA, enchances acquisition speeed) Decreased total acquisition times - faster acquisition reduces motion artifacts and venous contamination Improved spatial resolution – thinner slices and clear depiction of small vessels Significantly decreased contrast doses Noncontrast MRA

MRA – contraindications and limitations Defibrillators, pacemakers, spinal cord stimulators, intracerebral shunts, cochlear implants, or other devises Claustrophobia not amenable to sedation NSF (gadolinium-based contrast) Signal intensity dropout in metal stents Considerably more expensive – time consuming sequences to get better results (small vessels) Limited information regarding the character of the vessel wall Poor consensus on optimal protocols of scanning Continuing evolving of technology – both software and hardware

CT peripheral angiography  Dramatically shortened scanning times with 64 MSCT: From the diaphragm to the ankles <30sec Single contrast bolus  Improved spatial resolution = improved vascular image quality (smaller vessel)  Direct visualization of mural plaque and calcium  3D volumetric display and analysis  Visualization of extra luminal pathology  Patient easy/ perform study in outpatient setting  Low complication rate  Widespread availability  Cost effectiveness

FAST SCANNING + RAPID POST PROCESSING CT angiography Various 3D reconstructions MPR, MIP, VR

CT angiography – limitations and disadvantages Limited ability to depict the lumen in heavy calcified arteries- overstage the degree of stenosis Metal artifacts in stent surveillance, constantly improving diagnostic accuracy Different rates of calf vessel filling Insufficient arterial opacification, distal to occlusion Complications, related to iodinated contrast Cumulative radiation dose – low dose protocols New protocols – reduced radiation by decreasing kV with lower doses of iodinated contrast

CT angiography Future developments Dual Energy CTA Provide data from 2 KV settings Elemental specific attenuation Differentiation between Ca and iodine Automated bone and plaque subtraction can be applied. Dynamic, time resolved “4D”CTA CT digital subtraction angiography Dynamic scan data Blood flow dynamics, blood volume, mean transit time, time to peak, blood pool images.

Summary DSA remains the gold standard for diagnosing PVD, the only modality that allows diagnosis and simultaneous treatment of pathology Noninvasive imaging (CTA/MRA) before intervention or surgery are accepted and common Both CTA and MRT can be used and can positively influence management into percutaneous or surgical PVD is a significant and growing problem and continued research and development of current and emerging technologies will ultimately shape the standard of care.