Imaging of Non-atherosclerotic Vasculopathies

Abstract

Non-atherosclerotic vasculopathies (NAVs) may present with various neurological symptoms ranging from headache, stroke, visual symptoms, and various types of intracranial hemorrhage. NAVs result from different etiologies which include collagenopathies, immunological, hematological, and infection mechanisms, and other rarer unidentifiable or idiopathic causes. NAV etiologies account for about 10-15% and 20-25% of adult and pediatric stroke cases, respectively, and therefore, diagnosing the underlying cause of NAV becomes clinically very important. Clinical diagnosis of NAV is challenging because the clinical presentation is very non-specific and overlapping with various other central nervous system disorders. Before the advent of non-invasive techniques, making a diagnosis of non-atherosclerotic vasculopathy as a cause of the stroke was very challenging. Today with newer techniques such as high-resolution magnetic resonance (MR), MR and computed tomography perfusion, and angiogram, there are number of pointers which can give us a lead about the non-atherosclerotic causes. Imaging may provide the first lead to the clinician regarding the diagnosis or possible differential diagnosis so that the targeted and focused biomarkers (blood, cerebrospinal fluid, or/and in some cases biopsies) may be obtained to clinch the diagnoses. The purpose of the article is to enumerate the causes, clinical features, and illustrate the imaging findings of the various non-atherosclerotic vasculopathic disorders and discuss "pearls" to their diagnosis. In this article, we have also discussed the latest advances in vascular imaging and elaborated on few uncommon non-atherosclerotic vasculopathies. These are very relevant clinically in the day-to-day practice for the radiologist, neurologist, and the neurointerventionalist.

Keywords: Angiogram; Computed tomography angiography; Magnetic resonance angiography; Vasculopathy.

Figure 1:

Imaging appearances of dissection. Intramural thrombus: (a and b) Axial T1-weighted image shows decrease normal flow void (arrowhead) in the left ICA surrounded by a crescentic T1 hyperintense mural hematoma (arrow). Acute occlusion: (c) Contrast-enhanced MRA of the neck demonstrates flame like dissection (arrow) of the left ICA with complete occlusion of the lumen. (d) Contrast-enhanced MRA neck shows severe tapering (arrows) of the left ICA due to dissection.

Figure 2:

A 41-year-old male patient with acute-onset right hemiplegia due to spontaneous left ICA dissection. Axial source image from CTA shows dissection flap in the left carotid artery (arrowhead).

Figure 3:

Fibromuscular dysplasia. A 42-year-old woman presented with transient ischemic attacks. Conventional angiogram of the neck shows the “string and pearl” sign in the internal carotid artery consistent with fibromuscular dysplasia. Beaded appearance with multiocal areas of apparent narrowing (white arrows) noted.

Figure 4:

Dolichoectasia with pontine infarction in a 71-year-old male patient. (a) Reformatted MPR image of the intracranial CTA shows dolichoectasia of the vertebrobasilar artery with fusiform aneurysm of the vertebral artery (black arrow). Note is also made of the dysplastic middle cerebral arteries and aneurysms at the bifurcation (white arrow). (b) Axial DWI image shows acute stroke on the right side of the pons (arrow).

Figure 5:

Amyloid angiopathy. A 74-year-old male patient presented with dementia. (a) Axial T2-weighted fast spin-echo MR image does generalized prominence of convexity sulci and patchy T2 hyperintensity in the cerebral white matter. (b) Axial SWI MR image shows multiple foci of signal loss in cortical-subcortical locations, consistent with chronic microhemorrhages.

Figure 6:

A 36-year-old female with Ehlers-Danlos syndrome presented with severe headache. (a) CT scan of the head shows prepontine subarachnoid hemorrhage (arrow). (b and c) Prior CT angiogram of the brain depicted a complex saccular fusiform aneurysm at the vertebrobasilar confluence which has been stable over many years. (d) CTA of the lower extremities shows large tuft of coiled, vessels, complex pseudoaneurysm, and arteriovenous fistula arising from the proximal deep femoral artery bilaterally.

Figure 7:

A 51-year-old male patient with Marfan’s syndrome with multiple TIAs. Axial image from chest CTA reveals dissection in the arch and descending aorta (arrows). Dissection is also seen extending into the right brachiocephalic artery (arrowhead).

Figure 8:

Giant cell arteritis. A 61-year-old male patient with temporal artery biopsy proven case of giant cell arteritis. Contrast-enhanced MRA of the neck shows severe irregularities, narrowing and stenosis of the left vertebral (arrow), bilateral internal carotid (arrowheads). There is complete occlusion of the left external carotid arteries.

Figure 9:

A 59-year-old male patient with Takayasu arteritis. Contrast-enhanced MRA of the neck shows marked long segment narrowing of the common carotid arteries (arrows). There is severe narrowing of the left subclavian artery (curved arrow) with retrograde filling of the left vertebral artery (arrowhead) by the right vertebral artery “subclavian steal syndrome.”

Figure 10:

A 26-year-old male patient with Kawasaki disease presented with acute weakness on right side. (a) Coronal image of CT coronary angiogram shows large partially calcified aneurysms from the right (arrowhead) and left (arrow) coronary arteries. (b) Axial DWI image shows infarctions (arrow) in the left periventricular white matter.

Figure 11:

A 39-year-old female patient with CNS vasculitis presented with multiple transient ischemic attacks. (a) Axial FLAIR image shows multiple hyperintensities (arrows) in the cerebral white matter bilaterally. (b) Conventional angiogram of the brain shows multiple segmental narrowing of ACAs (arrows).

Figure 12:

Reversible cerebral vasoconstriction syndrome (RCVS). A 32-year-old female patient with non-aneurysmal pattern subarachnoid hemorrhage on CT. (a and b) Routine MR angiogram images moderate multifocal narrowing of bilateral ACAs, MCAs with beaded appearance of distal cortical branches (arrows). (c and d) High-resolution vessel wall imaging better delineates the segmental vasoconstriction seen on MRA (arrows). There was complete resolution of narrowing on the follow-up MRA done 2 months later (not shown here).

Figure 13:

CADASIL in a 43-year-old male patient with a history of migraine and multiple transient ischemic attacks. (a) Axial FLAIR images shows patchy hyperintensities (arrowheads) scattered throughout the supratentorial white matter bilaterally. (b) Axial FLAIR image shows classical hyperintensities in the anterior aspect of the temporal lobes (arrows).

Figure 14:

Moyamoya in a 28-year-old male patient with sickle cell disease. Frontal view of the conventional angiogram of the head shows severe narrowing of the right internal carotid artery (arrowhead) with puff of smoke (arrow) due to lenticulostriate collaterals. Multiple extracranial, transdural, and intracranial (curved arrows) collaterals are seen on the surface of the brain.

Figure 15:

Moyamoya in a 27-year-old female patient with sickle cell disease. (a) Frontal view of the conventional angiogram of the head shows severe narrowing of the carotid terminus, more prominent on the right. (b) Axial FLAIR image reveals bright signal within the sulcal vessels suggesting collateral flow (ivy sign: Yellow arrows). Coronal (c,d) and axial (e,f) vessel wall images show concentric wall thickening of bilateral carotid terminus and left proximal MCA. Wall enhancement along on the left MCA (yellow arrows).

Figure 16:

Acute infarction in a 36-year-old immunocompromised patient with aspergillosis. Axial contrast-enhanced CT images show multiple hypodense granulomas (arrowheads). Wedge shape hypodensity is seen in the right parietal lobe (arrows) consistent with acute infarction due to fungal vasculitis.

Figure 17:

A 2-year-old child with bacterial meningitis presented with acute weakness and involuntary movements. (a) Maximum intensity projection from time-of-flight head MRA shows severe narrowing of the left M1 segment (arrowhead) and mild spasm of the right M1 segment (arrow) of MCAs. (b) Axial DWI image shows infarctions (arrows) in the bilateral deep gray matter nuclei and thalami secondary to infective vasculitis and spasm.

Figure 18:

Cocaine vasculitis. A 31-year-old male patient presented to ER with acute-onset right-sided weakness. (a) Axial T2 image shows diffuse white matter hyperintensity due to vasculopathic changes. (b) Axial DWI image shows acute infarction (arrows) involving the left putamen and bilateral temporal lobe. (c) Time-of-flight MRA maximum intensity projection (MIP) shows acute cutoff of the left (arrow) and right (arrowhead) MCAs.

Figure 19:

A 41-year-old COVID-positive patient with ischemic stroke secondary to large vessel occlusion: Moderate size acute infarct in the left MCA territory on non-contrast head CT (a). Large ischemic penumbra noted on the Tmax perfusion maps involving the entire left MCA territory (b). Catheter angiogram shows complete occlusion beyond the carotid terminus (c) with significant revascularization post-thrombectomy (d).