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Dynamic MRI with slow injection of contrast material for the diagnosis of pituitary adenoma
1First Department of Radiology, Toho University School of Medicine, Tokyo, Japan.
Abstract:
Magnetic resonance (MR) imaging of pituitary adenoma is usually carried out in dynamic studies with bolus contrast material injections, with the result that few strong images are obtained. Dynamic studies using a slowly injected contrast material were carried out in 14 cases of pituitary adenomas. The examinations were performed with a 1.5 Tesla superconducting MR imaging system using the spin-echo technique. Gd-DTPA (0.1 mmol/kg) was slowly injected (within 90 sec) by hand, providing seven to nine dynamic images during 350 sec from the start of injection. The average time to reach the maximum signal intensity was 170.6 sec in adenoma and 156.2 sec in normal gland tissue. The maximum contrast signal intensity ratio of adenoma to normal gland was 0.527 in the fifth image. The contrast of adenoma to normal gland tissue was calculated by the following formula: ASII (adenoma signal intensity index) = (adenoma signal intensity-tissue signal intensity)/tissue signal intensity. The most remarkable contrast between adenoma and normal tissue was obtained from the fourth to eighth images. In other words, we could obtain the strongest contrast at 144.8 sec to 299.6 sec from the start of contrast injection. Our results with slow injection suggest that stronger images can be obtained a longer period after contrast injection.
Insights
Slow contrast injection in pituitary adenoma MRI yields stronger images. This technique enhances visualization of adenomas compared to normal gland tissue for a longer period post-injection.
Area of Science:
- Radiology
- Medical Imaging
- Endocrinology
Background:
- Standard dynamic magnetic resonance (MR) imaging for pituitary adenoma uses rapid contrast injections, often resulting in limited high-quality images.
- Pituitary adenomas require precise imaging for diagnosis and treatment planning.
Purpose of the Study:
- To evaluate the effectiveness of slow contrast material injection in dynamic MR imaging for pituitary adenomas.
- To determine if slow injection improves image quality and contrast between adenoma and normal pituitary tissue.
Main Methods:
- Performed dynamic MR imaging on 14 pituitary adenoma cases using a 1.5 Tesla superconducting system and spin-echo technique.
- Administered Gadolinium-DTPA (0.1 mmol/kg) via slow manual injection over 90 seconds, acquiring 7-9 dynamic images over 350 seconds.
- Calculated Adenoma Signal Intensity Index (ASII) to quantify contrast between adenoma and normal gland tissue.
Main Results:
- The average time to maximum signal intensity was 170.6 sec for adenomas and 156.2 sec for normal gland tissue.
- The maximum contrast signal intensity ratio of adenoma to normal gland was 0.527 at the fifth image.
- Optimal contrast between adenoma and normal tissue was observed between 144.8 sec and 299.6 sec post-injection.
Conclusions:
- Slow contrast injection in dynamic MR imaging allows for stronger, more prolonged contrast enhancement of pituitary adenomas.
- This technique provides improved visualization of adenomas compared to standard bolus injection methods.
- Slow injection is a promising method for enhancing diagnostic accuracy in pituitary adenoma imaging.