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Pediatric excretory MR urography: comparative study of enhanced and non-enhanced techniques
Arne S Borthne1, Claude Pierre-Jerome, Kjell I Gjesdal
1Department of Pediatric Radiology, Kirkeveien 166, Ullevaal University Hospital, 0407 Oslo, Norway. a-borthn@online.no
Abstract:
Our purpose was to compare the quality of ureteral imaging in pediatric patients using two different MR sequences: the non-enhanced heavily T2-weighted (W) turbo spin-echo sequence (TSE) and the gadolinium-enhanced T1W fast-field-echo sequence (T1 FFE). An experimental study on three pigs was first performed. The TSE, before and after furosemide injection, was followed by the T1 FFE sequence. The clinical study included 11 infants and 10 children. With some modifications the same MR parameters and techniques were used as in the animal study. The TSE with TR 8000 ms and TE 650 ms implied 6 radial stacks each of 40 mm thickness. The T1 FFE included TR 18 ms, TE 2.9 ms, flip angle 60, and 50 slices with thickness 0.7 mm. After post-processing, image reconstructions qualitative and quantitative analysis were performed. Complete visualization of the ureters was achieved in 35 of 42 (83%) cases. Seventy-four percent of the ureters were completely visualized with T1 FFE compared with only 19% with TSE. Sixty-nine percent of the ureters were better imaged with T1 FFE than TSE and 21% equally well imaged. Four ureters (10%), either obstructed or due to poor renal function, were better imaged with TSE. The two sequences are complementary. Visualization of non-obstructed ureters is excellent with T1 FFE and the sequence is superior to TSE. The TSE, however, may be equal to or even better than T1 FFE in visualizing obstructed ureters or ureters draining malfunctioning kidneys.
Insights
Gadolinium-enhanced T1W fast-field-echo (T1 FFE) MRI sequences offer superior ureteral imaging in pediatric patients compared to non-enhanced T2-weighted turbo spin-echo (TSE) sequences. However, TSE may be better for obstructed or poorly functioning kidneys.
Area of Science:
- Radiology
- Medical Imaging
- Pediatric Imaging
Background:
- Ureteral imaging in pediatric patients is crucial for diagnosing various conditions.
- Magnetic Resonance (MR) imaging offers non-invasive visualization techniques.
- Optimizing MR sequences is essential for accurate pediatric ureteral assessment.
Purpose of the Study:
- To compare the ureteral imaging quality between non-enhanced heavily T2-weighted (TSE) and gadolinium-enhanced T1W fast-field-echo (T1 FFE) MR sequences in pediatric patients.
Main Methods:
- An experimental study on pigs preceded a clinical study involving 21 pediatric patients.
- MR imaging was performed using specific parameters for both TSE and T1 FFE sequences.
- Qualitative and quantitative analyses of ureteral image reconstructions were conducted.
Main Results:
- Complete ureteral visualization was achieved in 83% of cases.
- T1 FFE sequences provided complete visualization in 74% of ureters, significantly outperforming TSE (19%).
- T1 FFE was superior for non-obstructed ureters, while TSE showed advantages in cases of obstruction or poor renal function.
Conclusions:
- Gadolinium-enhanced T1 FFE MR sequences are excellent for visualizing non-obstructed pediatric ureters.
- Non-enhanced TSE sequences can be complementary, offering better visualization for obstructed ureters or those draining malfunctioning kidneys.
- The choice of MR sequence should be tailored to the specific clinical scenario in pediatric ureteral imaging.