Diagnostic Performance of a Lower-dose Contrast-Enhanced 4D Dynamic MR Angiography of the Lower Extremities at 3 T
Paul Raczeck1, Peter Fries1, Alexander Massmann1
1Clinic for Diagnostic and Interventional Radiology, Saarland University Medical Center, Homburg, Saarland, Germany.
Background:
For peripheral artery disease (PAD), MR angiography (MRA) is a well-established diagnostic modality providing morphologic and dynamic information comparable to digital subtraction angiography (DSA). However, relatively large amounts of contrast agents are necessary to achieve this.
Purpose:
To evaluate the diagnostic accuracy of time-resolved 4D MR-angiography with interleaved stochastic trajectories (TWIST-MRA) by using maximum intensity projections (MIPs) of dynamic images acquired with reduced doses of contrast agent.
Study Type:
Retrospective.
Population:
Forty adult PAD patients yielding 1088 artery segments.
Field Strength/Sequence:
A 3.0 T, time-resolved 4D MR-angiography with TWIST-MRA and MIP of dynamic images.
Assessment:
DSA was available in 14 patients (256 artery segments) and used as reference standard. Three-segmental MIP reconstructions of TWIST-images after administration of 3 mL of gadolinium-based contrast agent (Gadoteridol/Prohance®, 0.5 M) per anatomical level (pelvis, thighs, and lower legs) yielded 256 artery segments for correlation between MRA and DSA. Three independent observers rated image quality (scale: 1 [nondiagnostic] to 4 [excellent]) and the degree of venous overlay (scale: 0 [none] to 2 [significant]) for all segments. Diagnostic accuracy for the detection of >50% stenosis and artery occlusion was calculated for all observers.
Statistical Tests:
Binary classification test (sensitivity, specificity, positive/negative predictive values, diagnostic accuracy). Intraclass correlation coefficients (ICCs), logistic regression analysis with comparison of areas under the receiver-operating-characteristics (ROC) curves (AUCs) with the DeLong method. Bland-Altman-comparison.
Results:
High diagnostic performance was achieved for the detection of >50% stenosis (sensitivity 92.9% [84.3-99.9% (95%-CI)] and specificity 98.5% [95.7-99.8% (95%-CI)]) and artery occlusion (sensitivity 93.1% [77.2-99.2% (95%-CI)] and specificity 99.1% [96.9-99.9% (95%-CI)]). Inter-reader agreement was excellent with ICC values ranging from 0.95 to 1.0 for >50% artery stenosis and occlusion. Image quality was good to excellent for both readers (3.41 ± 0.72, 3.33 ± 0.65, and 3.38 ± 0.61 [mean ± SD]) with good correlation between observer ratings (ICC 0.71-0.81). No significant venous overlay was observed (0.06 ± 0.24, 0.23 ± 0.43 and 0.11 ± 0.45 [mean ± SD]).
Data Conclusion:
MIPs of dynamic TWIST-MRA offer a promising diagnostic alternative necessitating only reduced amounts (50%) of gadolinium-based contrast agents for the entire runoff vasculature.
Evidence Level:
3 TECHNICAL EFFICACY: Stage 2.
Insights
Time-resolved 4D MR angiography (TWIST-MRA) with maximum intensity projections (MIPs) accurately detects peripheral artery disease (PAD) using half the standard contrast agent dose. This method offers a promising alternative for PAD diagnosis.
Area of Science:
- Radiology
- Medical Imaging
- Cardiovascular Disease
Background:
- Magnetic Resonance Angiography (MRA) is a key diagnostic tool for Peripheral Artery Disease (PAD), offering detailed anatomical and dynamic insights.
- Traditional MRA requires substantial contrast agent volumes, posing potential risks and increasing costs.
Purpose of the Study:
- To assess the diagnostic accuracy of time-resolved 4D MR angiography with interleaved stochastic trajectories (TWIST-MRA) using maximum intensity projections (MIPs).
- To evaluate the efficacy of TWIST-MRA with reduced contrast agent doses in diagnosing PAD.
Main Methods:
- Retrospective analysis of 40 adult PAD patients.
- Utilized 3.0T TWIST-MRA with MIP reconstructions.
- Compared MRA findings against Digital Subtraction Angiography (DSA) as the reference standard in 14 patients.
- Assessed image quality and venous overlay by three independent observers.
Main Results:
- High diagnostic performance for detecting >50% stenosis (sensitivity 92.9%, specificity 98.5%) and occlusion (sensitivity 93.1%, specificity 99.1%).
- Excellent inter-reader agreement (ICC 0.95-1.0) and good image quality (mean score ~3.4/4).
- Minimal venous overlay observed, not impacting diagnostic accuracy.
Conclusions:
- MIPs of dynamic TWIST-MRA demonstrate high diagnostic accuracy for PAD.
- This technique offers a viable alternative to conventional MRA, requiring only 50% of the standard contrast agent volume.
- TWIST-MRA with reduced contrast is a promising approach for PAD imaging.
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