Persistent and recurrent hyperparathyroidism: assessment with gadopentetate dimeglumine-enhanced MR imaging. The effect of gadopentetate dimeglumine on signal intensity of abnormal parathyroid glands was assessed in 14 patients with persistent and recurrent hyperparathyroidism. Non-contrast material-enhanced T1- and T2-weighted spin-echo images were compared with T1-weighted images obtained 1 minute and 10 minutes after administration of gadopentetate dimeglumine. Percentage of contrast between the abnormal gland and surrounding tissue was determined with the use of skeletal muscle, subcutaneous fat, and thyroid gland as reference tissues. All 11 abnormal parathyroid glands showed low to intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Gadopentetate dimeglumine significantly increased the signal intensity enhancement ratio of all abnormal parathyroid glands, causing increased percentage of contrast relative to the thyroid gland and skeletal muscle on T1-weighted images. However, the percentage of contrast relative to these tissues was even greater on nonenhanced T2-weighted images. Thus, gadopentetate dimeglumine can substantially enhance the signal intensity of abnormal parathyroid glands and improve differential contrast with some neighboring tissues on T1-weighted images, but it does not improve contrast with surrounding tissue beyond that achieved on T2-weighted images. 