A 2018 comparative study with 45 patients divided into noncontrast-enhanced and blood pool contrast groups was performed to qualitatively and quantitatively evaluate image quality as well as reproducibility [47]. This study concluded that IV contrast allows for higher quality imaging with more reproducible and accurate vessel measurements [47]. The findings were consistent with a 2010 study supporting the use of IV contrast for vascular detail [49]. In contrast to these findings, however, multiple other studies have found similar accuracy and reproducibility in assessing vessel diameter between contrast- and noncontrast-enhanced MRI studies [44,50,51]. MRA Chest, Abdomen, and Pelvis Without IV Contrast Multiple unenhanced MRA techniques such as time-of-flight, phase-contrast imaging, and steady-state free precision (SSFP) have been developed that allow for the evaluation of aortic dissection and aneurysm [44,45]. Even without IV contrast, MRA can be used to precisely evaluate the thoracoabdominal aorta size, as well as for access vessel size, intraluminal thrombus, and branch vessel involvement [37,39]. A 2017 observational study comparing AAA measurements in CTA and noncontrast MRA showed strong agreement, with intraclass coefficient >0.99 and interobserver reproducibility >0.99 for both CTA and MRA [45]. This study also noted a potential benefit of noncontrast MRA allowing evaluation of the composition of intraluminal thrombus, potentially allowing for risk quantification for disease progression [45]. This finding was also supported by a follow-up 2019 article [52]. Although some studies have shown more accurate measurements with contrast-enhanced MRA compared with noncontrast MRA, other studies have shown an equal ability to detect aortic pathology and to measure aortic size [44,50,51].
Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. A 2018 comparative study with 45 patients divided into noncontrast-enhanced and blood pool contrast groups was performed to qualitatively and quantitatively evaluate image quality as well as reproducibility [47]. This study concluded that IV contrast allows for higher quality imaging with more reproducible and accurate vessel measurements [47]. The findings were consistent with a 2010 study supporting the use of IV contrast for vascular detail [49]. In contrast to these findings, however, multiple other studies have found similar accuracy and reproducibility in assessing vessel diameter between contrast- and noncontrast-enhanced MRI studies [44,50,51]. MRA Chest, Abdomen, and Pelvis Without IV Contrast Multiple unenhanced MRA techniques such as time-of-flight, phase-contrast imaging, and steady-state free precision (SSFP) have been developed that allow for the evaluation of aortic dissection and aneurysm [44,45]. Even without IV contrast, MRA can be used to precisely evaluate the thoracoabdominal aorta size, as well as for access vessel size, intraluminal thrombus, and branch vessel involvement [37,39]. A 2017 observational study comparing AAA measurements in CTA and noncontrast MRA showed strong agreement, with intraclass coefficient >0.99 and interobserver reproducibility >0.99 for both CTA and MRA [45]. This study also noted a potential benefit of noncontrast MRA allowing evaluation of the composition of intraluminal thrombus, potentially allowing for risk quantification for disease progression [45]. This finding was also supported by a follow-up 2019 article [52]. Although some studies have shown more accurate measurements with contrast-enhanced MRA compared with noncontrast MRA, other studies have shown an equal ability to detect aortic pathology and to measure aortic size [44,50,51].