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High-resolution MR angiography: results in diseased arteries
P Gonschior1, I Pragst, G Valassis
1Inst. für exp. Onkologie, Klinikum rechts der Isar, Technische Universität, Munich, Germany. Peter.Gonschior@t-online.de
Insights
Respiratory-gated 3D magnetic resonance angiography (MRCA) can visualize coronary arteries, but its accuracy for detecting stenosis needs improvement. Further development of navigator echo sequences is required for reliable coronary artery stenosis assessment.
Area of Science:
- Cardiovascular Imaging
- Medical Physics
Background:
- Coronary artery disease diagnosis relies on invasive conventional coronary angiography.
- Non-invasive imaging techniques are sought to improve patient outcomes and reduce risks.
Purpose of the Study:
- To evaluate the utility of respiratory-gated 3D MRCA for coronary artery visualization.
- To compare the diagnostic performance of MRCA with conventional coronary angiography for stenosis detection.
Main Methods:
- A 1.5 Tesla scanner with a cardiac-gated and retrospective respiratory-gated 3D gradient echo sequence was used.
- Twenty healthy volunteers and twenty patients with proximal coronary artery stenosis were scanned.
- Image quality was assessed using a six-score grading system; stenosis detection was compared to conventional coronary angiography by blinded readers.
Main Results:
- Complete visualization of proximal coronary arteries was achieved in 55% (volunteers) and 69% (patients).
- Image quality decreased in middle (47%) and distal (20%) segments for both groups.
- For stenoses (n=53), MRCA sensitivity was 73% and specificity was 50%; with high image quality, sensitivity rose to 79% and specificity to 54%.
Conclusions:
- Respiratory-gated 3D MRCA allows for complete visualization of main coronary arteries, though image quality varies.
- The navigator echo technique shows potential but requires further optimization for reliable coronary artery stenosis assessment.
Abstract:
The purpose of this study was to investigate the value of a respiratory-gated three-dimensional (3D) magnetic resonance angiographic technique (MRCA) in identifying coronary arteries in healthy volunteers and patients with proximal coronary artery stenoses and to compare the results of the navigator echo technique in the assessment of coronary artery stenosis with conventional coronary angiography. Twenty healthy volunteers and twenty patients with proximal coronary artery stenosis were examined at 1.5 Teslas with a cardiac-gated and retrospective respiratory-gated 3D gradient echo sequence. Visualization of the main coronary arteries was analyzed after curved MPR-reconstruction in three defined segments. For the assessment of image quality, a grading system including six scores was used to evaluate 400 vessel segments. Detection of coronary artery stenosis was compared with conventional coronary angiography by two blinded readers. In healthy volunteers, an image quality with a score of at least 3 (i.e., completely identified coronary arteries with major luminal irregularities) was found in 55% for the proximal segment, 47% for the middle segment and 20% for the distal coronary artery segment. Respective data for patients were 69% for the proximal segment, 47% for the middle segment and 20% for the distal segment. In contrast to other studies, we compared MRCA and conventional coronary angiography in the assessment of stenoses for all coronary vessels and for selected coronary vessels with high image quality. For the assessment of coronary artery stenoses (n = 53), sensitivity was 73% and specificity was 50% after evaluation of all patients by two blinded readers. A sensitivity of 79% and a specificity of 54% were found for evaluation of coronary vessels with an image quality score of at least 3. With the navigator echo MR technique, a complete 3D visualization of the main coronary arteries is possible in cases with variable image quality, but further experience and improvement of the prospective navigator echo sequence using shorter acquisition times is necessary for reliable assessment of coronary artery stenoses.