Computed tomography angiography (CTA) is a primary diagnostic tool for Fibromuscular Dysplasia (FMD).
FMD diagnosis primarily relies on imaging techniques to visualize the affected arteries. Here's a breakdown of the diagnostic process:
1. Imaging Studies:
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Computed Tomography Angiography (CTA): This is often the preferred initial imaging modality. CTA is non-invasive, accurate, and produces high-resolution images. A key finding in medial FMD is the characteristic "string-of-beads" appearance, which results from alternating areas of arterial narrowing and dilation. CTA can also reveal renal aneurysms and infarcts if the renal arteries are affected.
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Magnetic Resonance Angiography (MRA): MRA is another non-invasive option that uses magnetic fields and radio waves to create detailed images of blood vessels. Like CTA, MRA can detect the "string-of-beads" appearance.
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Catheter-Based Angiography (Arteriography): This is an invasive procedure where a catheter is inserted into an artery and a contrast dye is injected to visualize the blood vessels using X-rays. While it's considered the "gold standard," it's typically reserved for cases where other imaging results are unclear or when intervention (e.g., angioplasty) is being considered. Due to its invasive nature and associated risks (e.g., stroke, bleeding), it is not typically the first-line diagnostic test.
2. Clinical Evaluation:
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Medical History and Physical Exam: The doctor will review the patient's medical history, including any symptoms suggestive of FMD (e.g., high blood pressure, pulsatile tinnitus, stroke, transient ischemic attack (TIA)). A physical exam will be conducted to assess blood pressure and listen for bruits (abnormal sounds) over the arteries.
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Laboratory Tests: While there are no specific blood tests to diagnose FMD directly, certain tests may be performed to rule out other conditions or assess the impact of FMD on organ function (e.g., kidney function tests).
3. Diagnostic Criteria:
- The diagnosis of FMD is typically based on imaging findings consistent with the disease in conjunction with clinical symptoms.
In summary, diagnosing FMD involves a combination of clinical evaluation and, most importantly, imaging studies like CTA, MRA, or catheter-based angiography to visualize the affected arteries and identify characteristic features like the "string-of-beads" appearance.
