Technetium-99m pentavalent dimercaptosuccinic acid imaging in patients with pituitary adenomas

Abstract

We studied the tumor-seeking agent technetium-99m-labeled pentavalent dimercaptosuccinic acid ([99mTc](V)DMSA) to visualize 21 growth hormone (GH)-, nine prolactin (PRL)-, two mixed GH/PRL-, six adrenocorticotrophin (ACTH)-secreting and 15 clinically non-functioning pituitary adenomas, three craniopharyngiomas and one dysgerminoma of the sella. All non-adenomas and 31 out of 53 adenomas were studied before treatment: 22 after surgery and/or radiotherapy. Eight cases of acromegaly were studied before and after chronic treatment with octreotide, whereas three cases of acromegaly, one of prolactinoma and two of non-functioning adenoma were imaged before and after adenomectomy. As a control group, 27 patients without any clinical evidence of pituitary adenoma were studied: 10 of them were operated on previously and treated with iodine-131 for metastatic thyroid carcinoma, 10 had brain tumors and the remaining seven patients had functional pituitary hypersecretion (four Klinefelter's syndrome, two primary hypothyroidism and one Addison's disease). The scintigraphy was repeated after testosterone in Klinefelter's syndrome, L-thyroxine in primary hypothyroidism and cortisone administration in Addison's disease. Seventeen GH-secreting (81%), seven PRL-secreting (78%), three ACTH-secreting (50%), 15 non-functioning (100%) and one (50%) mixed adenoma significantly concentrated [99mTc](V)DMSA, showing elevated tumor-to-background (T/B) ratios. The T/B ratios were similar in untreated and surgically treated adenomas (11.2 +/- 5.6 vs 11.8 +/- 6.2). Radiotherapy significantly lowered the [99mTc](V)DMSA uptake to 5.1 +/- 2.8 (p < 0.1 vs untreated patients). Non-adenomatous lesions of the sella turcica did not concentrate [99mTc](V)DMSA in the pituitary as well as brain tumors and 8 out of 10 metastatic thyroid cancers. The treatment with octreotide normalized GH and insulin-like growth factor I levels and reduced [99mTc](V)DMSA from 15.7 +/- 4.8 to 13.5 +/- 3.9 (p < 0.05). Conversely, adequate substitutive therapy completely inhibited the uptake of the radiotracer in Klinefelter's syndrome, in primary hypothyroidism and in Addison's disease. The [99mTc](V)DMSA scintigraphy showed an overall sensitivity of 81% (43/53) in detecting pituitary adenomas, which was increased to 95% for lesions greater than 10 mm in size. High-quality images with minimal total body radiation were obtained, enabling a good in vivo characterization of viable adenomatous tissue as well as an accurate monitoring of the effects of different therapeutic regimens.

Differentiation of Pituitary Adenomas From Other Sellar and Parasellar Tumors by 99mTc(V)-DMSA Scintigraphy

“…9) In our series, marked diffuse accumulations of 99m Tc(V)-DMSA were observed in 17 of 21 patients with pituitary adenomas, especially seven of seven non-functioning adenomas, but not in patients with non-pituitary adenomas. These results suggest that 99m Tc(V)-DMSA can visualize pituitary adenomas clearly, and diffuse accumulation of 99m Tc(V)-DMSA could differentiate non-functioning adenoma from non-pituitary adenomas using only the planar image.…”

“…14) However, 99m Tc(V)-DMSA may accumulate only in endocrinological`u nbalanced'' pituitary glands. 9) In our series, no The neuroimaging characteristics of lesions are based primarily on the density differences and extravasation of contrast material in CT and differences in water content and water binding in MR imaging. 1) These features that control the signal intensity are frequently similar in various types of tumors, so the differential diagnosis is more often based on anatomical relationships, such as the deformation of adjacent structures.…”

“…7,11,12) Although the exact mechanism of tumor accumulation of 99m Tc(V)-DMSA remains to be elucidated, in general, non-specific trapping is justified. 3,9) We believe that some factors affect 99m Tc(V)-DMSA accumulation in pituitary adenomas, such as endocrinic activity, vascularity, and permeability, but not cell proliferation or tumor size.…”

99mTechnetium pentavalent dimercaptosuccinic acid scintigraphy in the follow‐up of clinically nonfunctioning pituitary adenomas after radiotherapy

“…Purity and radiochemical quality controls demonstrated that over 98% of injectable preparations was 99m Tc(V)DMSA; less than 1% was, respectively, 99m Tc(III)DMSA or free 99m Tc pertechnetate. In fact, in early and in late images, the thyroid and gastric mucosa, which have avid uptake of free‐pertechnetate, were not visualized (Lastoria et al ., 1996).…”

“…In a previous study (Lastoria et al ., 1995), we reported that technetium‐99m pentavalent dimercaptosuccinic acid [ 99m Tc(V)DMSA], a tumour seeking agent previously shown to detect medullary thyroid cancer (Ohta et al ., 1984), head and neck squamous tumours (Watkinson et al ., 1989) and skeletal lesions from breast cancer (Kashyap et al ., 1992), was significantly concentrated in the majority of pituitary adenomas (up to 93% of those greater than 10 mm in size). The uptake of 99m Tc(V)DMSA was similar in untreated and surgically treated adenomas while it was significantly reduced after radiotherapy (Lastoria et al ., 1996).…”