Introduction:
Inflammation of the arteries is a common feature of the condition known as vasculitis. The location and the kind of blood vessels involved determine the clinical and pathological characteristics. Any blood vessels, regardless of kind, of any organs in the body may be impacted. More than 30 different types of vasculitis have been identified by research. Vasculitis can appear as a primary condition or a result of another underlying condition. The etiology of vasculitis and inflammatory processes involves the endothelium (the inner layer of the blood vessels). Increased vascular permeability or vessel wall rupture results from inflammatory cell infiltration-induced vessel wall thinning. As a result, an organ is impacted by hemorrhage. Depending on the site of involvement, the clinical presentation varies. Organ ischemia or infarction results from the narrowing or total obstruction of the afflicted vessel due to vascular intimal proliferation and intraluminal thrombus development.
The release of chemical mediators from inflamed blood vessels also causes a systemic inflammatory response, resulting in various non-specific systemic symptoms. In addition to test findings, including normocytic and normochromic anemia, leucocytosis, thrombocytosis, and elevated erythrocyte sedimentation rate (ESR), and C reactive protein (CRP), they also include fever, night sweats, malaise, weight loss, arthralgia, and myalgia. Research into various imaging techniques has been vigorous due to technological advancements and a greater understanding of the occurrence and effects of vasculitis. The role of imaging in diagnosing and monitoring vasculitis is astounding, which is further discussed in this article.
What Are the Imaging Techniques Used in the Diagnosis and Monitoring of Vasculitis?
1. Duplex Ultrasonography (DUS):
It has been suggested that ultrasonography is an essential technique for assessing vasculitic diseases, particularly large-vessel vasculitis. Regarding inflamed arteries, there are three common ultrasonic findings:
Lumen stenosis.
Lumen edema.
Occlusion.
The "halo sign" results from intimal edema forming a hypoechoic ring at the edge of the lumen. This examination aid in the accurate diagnosis and formulation of a treatment strategy by a vascular surgeon. In addition, a non-invasive method of assessing blood flow through the arteries and veins is duplex ultrasonography. A Doppler ultrasound, which records sound waves that bounce off moving objects to evaluate blood flow and speed, is combined with a regular ultrasound to create a duplex ultrasound, which creates images by recording sound waves that bounce off blood vessels. DUS is reported to be a trustworthy method for identifying vessel wall inflammation and for monitoring hemodynamic changes in response to therapy in patients with vasculitis.
2. Infrared Thermography:
Atherosclerotic plaques in the blood vessels raise the local temperature due to a local acute inflammatory response. In contrast to normal carotid artery blood flow, adequate blood perfusion to the skin tissues of the face and forehead will be negatively impacted if the carotid artery is wholly or partially blocked, and the skin temperature in the area will also be reduced. Infrared thermography detects radiation (heat) emitted from body parts, converts it to temperature, and shows an image of the temperature distribution. By identifying higher thermal signals, infrared thermography equipment aids in evaluating body regions that may be affected by vasculitis. Additionally, this imaging method can offer follow-up monitoring data to assess the effectiveness of the treatment. The cost of thermal imaging cameras with high spatial resolution, the need for substantial training for interpretation, and the effects of the working environment (such as temperature, humidity, and airflow) on the results are just a few of the drawbacks of thermal imaging cameras. However, a cell phone-mounted infrared thermographic camera has also been developed due to the widespread adoption of smartphones. As a result, this technique has shown to be a convenient and affordable supplementary imaging tool in treating vascular patients.
3. Contrast‐Enhanced Magnetic Resonance imaging (MRI):
The preferred method for assessing damaged soft tissue is MRI. High-resolution MRI is equally sensitive and selective in detecting inflammatory vascular wall alterations. MRI is the preferred imaging test for determining vasculitis's severity and activity. For instance, on contrast-enhanced MRI, aortic wall thickening will be heavily stained with gadolinium if acute-phase Takayasu disease (TAK) is present. Contrast-enhanced MRI with magnetic resonance angiography is the preferred technique in conditions where CNS vasculitis is suspected.
4. Magnetic Resonance Angiography (MRA):
The detection rate of MRA for carotid artery stenosis is allegedly higher than that of other angiography, particularly for mild stenosis. It can assess changes in the vessel lumen and vessel wall inflammation. Additionally, artery lumen narrowing, occlusion, and aneurysm development can be assessed by MRA. MRA is frequently helpful for interpreting symptoms associated with ischemia since it may clearly show whether or not there are any abnormalities, contractions, or blockage of the arterial walls.
5. Computed Tomography Angiography (CT/A):
An alternative option for MRI is CT paired with CT angio because it can also see significant vessel changes, such as important stenosis of large vessels, vessel occlusion, or aneurysms, as well as already-occurring major alterations to the brain parenchyma. In addition to inflaming the medium and small arteries, Polyarteritis nodosa can result in many microaneurysms and/or contractions. Angiograms are routinely used to confirm the presence of aneurysms in the renal, mesenteric, and hepatic arteries, which are the abdominal aorta branches.
6. F‐Fluorodeoxyglucose‐Positron Emission Tomography (FDG‐PET):
CT is frequently used with FDG-PET. In both infectious and noninfectious inflammatory disorders, FDG-PET is often employed because activated white blood cells have enhanced glucose metabolism. It offers functional details on the metabolic processes in organs and tissues. FDG-PET can therefore be employed before the onset of morphological defects and inflammatory edema, aiding in early identification. Patients with Takayasu arteritis with atypical clinical signs may benefit from FDG-PET for disease diagnosis and activity monitoring. F-fluorodeoxyglucose positron emission tomography (FDG-PET) may pinpoint the location of aortic inflammation. In order to detect F-FDG uptake in the wall of the thoracic and abdominal aorta where chronic inflammation is prevalent, this strategy requires highly specialized imaging equipment with radioactive tracer delivery and skilled professionals to execute the imaging examination. Due to financial constraints, adapting this imaging technique by doctors or hospitals, in general, is difficult.
7. Superb Microvascular Imaging (SMI):
SMI, a brand-new vascular imaging mode, makes it possible to see low-velocity microvascular flow. It is a simple, secure, and non-intrusive technique. However, the need for clinical guidelines and the requirement for training to administer the test and interpret the results are limitations of SMI.
Conclusion:
The imaging methods are essential for detecting, managing, and monitoring vasculitis. Imaging modalities like ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and other novel imaging techniques enable accurate identification of affected blood vessels and assessment of disease activity due to their non-invasive nature and capacity to provide detailed visualizations. These methods help in the early discovery of vasculitis, assessing the severity and scope of the disease, and monitoring the effectiveness of treatment. Imaging techniques significantly contribute to thorough care and better results for patients with vasculitis by offering insightful information about the vascular system.
