Reduced metallic artefacts in 3 T knee MRI using fast spin-echo multi-point Dixon compared to fast spin-echo
H J Park1, S Y Lee1, S H Choi1
1Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Aim:
To compare multi-point Dixon magnetic resonance imaging (MRI) and fast spin-echo (FSE) T2-weighted imaging (WI) with regard to the size of metallic artefacts when imaging the knee joint.
Materials And Methods:
A total of 42 patients who underwent anterior cruciate ligament (ACL) reconstruction and follow-up imaging with 3 T MRI using the multi-point Dixon technique was included in this retrospective study. The maximal distance of the image distortion area around the metallic artefact was measured (interference screw of femoral tunnel area) on sagittal images of both FSE T2WI (T2WI and fat-suppressed [FS] T2WI) and multi-point Dixon (water only image and in-phase image) sequences. The maximal distance of the image distortion were compared using paired t-tests across the image sequences (multi-point Dixon water only image versus FS T2WI and multi-point Dixon in-phase image versus T2WI).
Results:
The mean distance of the image distortion from metallic artefacts regardless of the image sequence ranged from 16.6 mm to 24.5 mm (Table 2). The mean distances measured by two readers on multi-point Dixon (water only image) sequences were significantly shorter than those in FS T2WI sequences (p<0.001). In contrast, the mean distances measured by two readers on multi-point Dixon (in-phase image) sequences did not differ from those of T2WI (p>0.05) sequences.
Conclusion:
The water-only image of multi-point Dixon technique reduces the amount of metallic artefacts compared to that in FS FSE T2WI sequences; however, the metallic artefacts were not significantly different between in-phase images of multi-point Dixon and FSE T2WI.
Insights
The multi-point Dixon MRI technique, specifically its water-only image, significantly reduces metallic artifact size around knee implants compared to fast spin-echo T2-weighted imaging. In-phase images showed no significant difference.
Area of Science:
- Radiology
- Medical Imaging
- Orthopedic Surgery
Background:
- Metallic implants, such as interference screws used in anterior cruciate ligament (ACL) reconstruction, cause image artifacts in magnetic resonance imaging (MRI).
- These artifacts can obscure surrounding anatomy, potentially impacting diagnostic accuracy.
- Fast spin-echo (FSE) T2-weighted imaging (WI) is commonly used but is susceptible to metallic artifacts.
Purpose of the Study:
- To compare the size of metallic artifacts generated by multi-point Dixon MRI and FSE T2-WI in the knee joint.
- To evaluate the effectiveness of different multi-point Dixon sequences (water-only and in-phase) in reducing artifact size compared to standard FSE T2-WI.
Main Methods:
- A retrospective study included 42 patients with ACL reconstruction imaged using 3 Tesla (3T) MRI.
- Metallic artifact size was measured as the maximal distance of image distortion around interference screws on sagittal images.
- Artifacts were assessed using FSE T2WI (T2WI, fat-suppressed T2WI) and multi-point Dixon (water-only, in-phase) sequences.
Main Results:
- The mean artifact distance ranged from 16.6 mm to 24.5 mm across sequences.
- Multi-point Dixon water-only images showed significantly smaller artifact distances compared to fat-suppressed FSE T2WI (p<0.001).
- No significant difference in artifact size was found between multi-point Dixon in-phase images and standard FSE T2WI (p>0.05).
Conclusions:
- The water-only image of the multi-point Dixon technique effectively reduces metallic artifacts compared to fat-suppressed FSE T2WI.
- The in-phase images of multi-point Dixon do not offer a significant advantage over standard FSE T2WI in artifact reduction.
- Multi-point Dixon MRI, particularly the water-only sequence, shows promise for improved imaging of metallic implants in the knee.
