ARRS 2022 Abstracts

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E1593. Application of Coronary Non-Contrast MR Angiography for Patients with Suspected Coronary Artery Diseases
Authors
  1. Shoichi Takekawa; Southern Tohoku General Hospital
  2. Hirotsugu Munechika; Southern Tohoku General Hospital
  3. Toshiyuki Saginoya; Southern Tohoku General Hospital
  4. Hidekazu Yamazaki; Southern Tohoku General Hospital
  5. Takashi Konno; Southern Tohoku General Hospital
  6. Yoshihiro Chiba; Southern Tohoku General Hospital
Background
The purpose of this exhibit is to elucidate the practical usefulness and limitations of coronary non-contrast-enhanced MR angiography (MRA), especially for patients with heavily calcified coronary arteries, decreased renal function, or known allergic reaction to iodinated contrast media.

Educational Goals / Teaching Points
To understand the possible and useful application of coronary non-contrast MRA for patients with heavily calcified coronary arteries, decreased renal function, and known allergic reaction to iodinated contrast media.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Between July 2016 and August 2021, 50 coronary non-contrast MRAs were performed. MRA images include: heavily calcified (9 cases) or stented (4 cases) coronary arteries, chronic total arterial obstruction (3 cases), aneurysms of coronary arteries (2 cases), patients with a known allergic reaction to iodinated contrast media (5 cases), and renal dysfunction (22 cases). Two patients preferred to have non-contrast MRA owing to fear of contrast media side effects. In 22 cases, CT angiography (CTA) or coronary angiography (CAG) was available to compare with MRA. Only MRA was taken in 28 patients with past histories of allergic reaction to iodinated contrast media and renal dysfunction. The MRA images were graded as “good” (clear image), “fair” (inferior but readable), and “poor” (poor image) and grouped according to the three major coronary arteries [left anterior descending (LAD), left circumflex (LCX), right coronary artery (RCA)] measuring 2 mm or more in diameter. A 1.5T MRI machine with 3D Heart [GE] and a 32-channel cardiac coil were used. Free-breathing (respiration navigation) and ECG-gated data were utilized. The gradings of the three coronary artery groups were as follows. LAD: good (86%), fair (6%), poor (8%); LCX: good (76%), fair (10%), poor (14%); RCA: good (94%), fair (4%), poor (2%). Limiting factors were high pulse rates (over 90/min), irregular respiration, and arrhythmia. There was a false negative case with total obstruction of the coronary arteries and a false-positive diagnosis due to over-reading. The MRAs were fairly well correlated with CTA or CAG. A calcified coronary artery on CTA, obscuring the lumen of the artery, was clarified as having a patent lumen of the artery by non-contrast MRA. Stented arteries appeared as either absent images or patent narrow lumen. Chronic total obstructions appeared as various images, including complete occlusion or partial or narrow lumen. Coronary artery aneurysms due to Kawasaki disease or arteriosclerosis were well depicted by MRA.

Conclusion
Coronary non-contrast-enhanced MR angiography (MRA) is clinically useful and beneficial in patients with heavily calcified coronary arteries on CT or CTA, decreased renal function, and known allergic reaction to iodinated contrast media, although some limitations exist.