Each modality follows a different signal associated with circulation. Contrast agents, radioactive tracers, or ultrasound signals reveal how blood moves through the vascular system and tissues. The resulting measurements can emphasize regional blood volume, transit time, or perfusion distribution, allowing clinicians to examine circulation from complementary perspectives rather than relying on a single indicator.
Blood volume indicates how much blood is present within a region, while transit time reflects how long circulation takes to pass through it. Examining these measurements together helps identify abnormal delivery or movement of blood, including areas that may receive inadequate circulation. This distinction supports more informative assessment than observing vascular anatomy alone.
Microvascular assessment focuses on circulation within small vessels and tissue beds that may not be adequately characterized by examining larger arteries or veins alone. By mapping perfusion in microvascular tissues, the technique can reveal regional differences in tissue supply. This is particularly relevant when organ or tissue viability depends on the quality of local circulation.
Perfusion maps show whether circulation is reduced, uneven, delayed, or otherwise abnormal across an organ or tissue region. Comparing these spatial and timing patterns helps clinicians recognize impaired blood delivery and characterize vascular behavior rather than simply confirming that vessels are present. Such information can support diagnosis and help evaluate the functional significance of a vascular abnormality.
The workflow begins by selecting an imaging approach suited to the circulation being evaluated. The study then tracks an injected contrast agent, radioactive tracer, or ultrasound signal as it passes through arteries, veins, and tissues. Measurements are converted into perfusion information, including blood-flow patterns, blood volume, or transit time, for clinical interpretation.
Its clinical uses include evaluating stroke, peripheral arterial disease, tumors, myocardial ischemia, and organ viability. In these settings, the measurements can reveal regions with impaired or abnormal circulation, help clinicians assess the extent of a problem, and contribute to treatment planning. Repeated studies may also help monitor whether a therapy changes perfusion over time.