Takayasu arteritis (TA) and giant cell arteritis (GCA) are chronic, inflammatory large artery vasculopathies (LAV), that necessitate early diagnosis as prompt initiation of treatment can prevent or delay the onset disease-related morbidities including blindness, limb ischemia, and hemorrhage secondary to chronic vessel stenosis, occlusion, aneurysm formation, and the harmful side-effects of overtreatment in later stage disease(1-3). Unfortunately, early detection has historically been difficult due to the vague nonspecific clinical presentation, with most people presenting with nonspecific symptoms, including dizziness, syncope, and fatigue and limitations of laboratory evaluation(3 4). As a result, accurate clinical diagnosis is often delayed by approximately 10-15.5 months from symptom onset, or even greater in pediatric patients(5 6). Historically, diagnostic imaging in LAV has primarily relied on luminal evaluation, specifically CT angiography (CTA) and MR angiography (MRA), with studies aimed at establishing and grading the degree of vascular stenosis or occlusion(7 8). Luminal imaging techniques, however, can only detect disease involvement when significant luminal narrowing is present (typically not the case early in the disease), and provide limited soft tissue and vessel wall information(7-9). Thus, imaging modalities that provide vessel wall information are particularly useful when diagnosing and managing large vessel vasculitis syndromes. There has been a recent focus on vessel wall imaging using MR vessel wall imaging techniques (VWI) that directly visualize the vessel wall itself in order to establish vessel wall involvement by the presence or absence of enhancement indicative of active inflammation(3 4 10-13). This study performs a quantitative and qualitative comparison between 3D T1 VISTA (Philips Healthcare, Best, the Netherlands) and 2D T1 black blood imaging of the aorta and cervical arteries to determine the differential quality of each technique in patients referred for suspicion of LAV.

MR Imaging Protocol: Patients referred for evaluation of potential LAV who received both 3D and 2D VWI MRI before and after contrast administration were included. The 3D and 2D sequences were performed in random order for each patient. Imaging parameters are in Table 1.

Image Analysis: Blinded independent review was performed by two experienced diagnostic neuroradiologists. Blood signal suppression, image quality, and diagnostic confidence were each rated using a four-point scale. The ratings from each neuroradiologist were averaged for the data analysis. A separate rater evaluated vessel wall and soft tissue SNR and CNR for cervical and aorta images for both techniques. Two-tailed paired t-tests were performed to compare differences between 2D and 3D techniques.

Eight patients were recruited and underwent 2D and 3D imaging. Cervical arteries were imaged in all patients while the aorta was imaged in 6 of 8. 2D VWI demonstrated significantly increased SNR and CNR of the vessel wall (.031 and .026, respectively) for images of the cervical arteries. 3D images had better soft tissue SNR (p=.005) for the thoracoabdominal aorta (Table 2). Blood suppression, overall image quality and diagnostic confidence ratings of the cervical images were significantly higher for the 3D images than the 2D images (Table 3). For the aortic images, blood suppression and image quality ratings were significantly higher for the 3D images than the 2D images (Table 4), with a trend towards higher diagnostic confidence (p=0.054). 3D imaging provided increased coverage relative to 2D imaging, with 300 (aorta) and 200 (cervical) mm craniocaudal coverage, while 2D imaging provided 225 mm (aorta) and 94 mm (cervical) coverage. 3D VWI scan time was shorter compared to 2D VWI (Table 1).Both 2D and 3D pulse sequences are useful for black blood MR VWI. 3D sequences allow for increased coverage, higher resolution and multi-planar reformats in a potentially shorter scan time. This current study compared 2D and 3D VWI sequences obtained during the same study. Radiologist reviewers perceived significantly improved blood suppression and image quality as well as increased confidence in their ability to diagnose disease with 3D VWI techniques as compared to 2D VWI. 3D VWI also provided improved coverage in a shorter scan time and improved SNR for aortic imaging, though decreased SNR and CNR in cervical evaluation, which may be related to signal loss at the edge of the imaging field of view. 3D VWI using techniques such as VISTA for evaluation of LAV should be a clinical consideration based on the above advantages as well as the ability to perform multiplanar reformats.3D VWI for evaluation of LAV should be a clinical consideration based on radiologist-perceived advantages, improved coverage in a shorter scan time.