Clinicai Study Of Dynamic MRI For Pituitary Adenomas

Object:To determine the clinicalsignificance of dynamic magnetic resonance imaging (MRI) for pituitary adenomas,analyses sequential enhancement patterns of pituitary adenomas and factors contributing to these sequential patterns and the value of dynamic MR imaging in pituitary adenomas including postoperrative pituitary tumors.Methods:Dynamic MRI was performed in ten patients with suspected microadenomas but no lesion were found in plane scan and routine enhancement, and forty-six cases of macroadenoma detected in plane scan.The study was performed on a 1.5T super conducting MR imaging NV/I system with Echo planar imaging technique. Gadodiamide (0.2mmol/Kg) was administered .Dynamic coronal imagings were obtained delaying 5 seconds from injection .Forty imagings were obtained within 252 seconds for each patient.Result:Eight microadenomas were depicted as relatively low intensity in the later dynamic and delay scan of ten suspected pituitary adenomatous lesion patients.Dynamic study did not add to the diagnosis. Time- density curves were clssified into three categories according to the sequential enhancement patterns of the adenomas.Factors supposed to correlate with enhancement pattern,such as hormone ,tumor size ,microscopically examined vasularity and arterial involvement ,and intraoperatively observed texture of the adenomas,were examined among the groups.Adenomas inclined to have low peak enhancement curve patterns were relatively small compared to those with high peak patterns .Tumors with high peak enhancement patterns were significantly more fibrous than those the other two patterns. Peripheral rim enhancement was seen in 2 patients of macroadenomas and 7 patients of macroadenomas showed nodular enhancement of follow-up dynamic MR imaging one month after operation.and eight patients of microadenomas showed no enhancement on dynamic MR imaging.Conclusion:Dynamic MR imaging has emerged as a technically refined tool in the detection and evalution of pituitary adenomas.The key questions in the evaluation of pituitary adenomas include the presence or absence of a tumor ,the number,the location of adenomas nodule ,the invasive effects on adjacent structures.Also,early postoperative MR imaging is useful in the detection of residual tumor. Since the early postoperative sella retains its preoperative volume, one can easily differentiate residual tumor from a normal gland, implanted materials, or postsurgical granulation tissue.Clearly,dynamic MR imaging is the foremost imaging modality answering these vital question in patients with pituitary adenomas.