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R O'Mara

Publications and source records attributed to R O'Mara.

9 recordsLinked to original sources
PubMed1998

The diagnostic utility of dual phase Tc-99m sestamibi parathyroid imaging.

PURPOSE: Primary hyperparathyroidism is a disease of uncertain etiology that results from hypersecretion of parathyroid hormone (PTH) by the parathyroid gland. In most institutions, the preferred imaging protocol utilizes a dual-phase technique with Tc-99m sestamibi which is reported to be more sensitive than earlier protocols involving TI-201 with Tc-99m pertechnetate subtraction. The purpose of this study is to evaluate the accuracy and clinical utility of Tc-99m sestamibi dual-phase scintigraphy for localizing hyperfunctioning parathyroid tissue. MATERIALS AND METHODS: We retrospectively reviewed thirty-nine consecutive hyperparathyroid patients who received a dual-phase Tc-99m sestamibi parathyroid scan. Thirty-seven of the subjects subsequently underwent a bilateral neck exploration and parathyroidectomy. Each scan interpretation was then correlated with the histopathologic diagnosis and the patients' post-surgical clinical course. RESULTS: The sestamibi dual-phase imaging protocol correctly localized 21 of 25 parathyroid adenomas and identified 8 out of 10 cases of hyperplasia. Our overall sensitivity and specificity were 83% and 75%, respectively. In addition, four of the adenomas were successfully localized intraoperatively using a gamma probe. CONCLUSION: Parathyroid imaging with sestamibi appears to be superior to TI-201/Tc-99m pertechnetate subtraction based on the reported results of both techniques at various institutions. Dual-phase sestamibi imaging appears to be useful and cost-effective for presurgical localization of hyperfunctioning parathyroid tissue. In addition, sestamibi imaging in conjunction with an intraoperative probe is a very promising technique that has the potential to provide both localization information of a suspected parathyroid adenoma and to facilitate its surgical removal by reducing operation time.

Adenoma↗
PubMed1996

Remission of acromegaly caused by pituitary carcinoma after surgical excision of growth hormone-secreting metastasis detected by 111-indium pentetreotide scan.

GH-secreting carcinomas of the pituitary are extremely rare. We describe a 37-yr-old woman with refractory acromegaly 15 yr after transphenoidal surgery and radiotherapy, with no evidence of a recurrent pituitary mass. Scanning with 111-indium pentetreotide revealed an area of intense activity in the left neck. A 3.5 x 2.5-cm mass was excised from the neck after demonstrating an arterio-venous GH gradient of 7:1. GH levels (50 ng/mL) dropped to 0.8 ng/mL 3 h after surgery and remained normal. GH gene expression was demonstrated in the metastasis by Northern and Western blot analyses and by positive immunocytochemistry and immunoelectron microscopy. In vitro cultured cells responded to GHRH and TRH by increasing GH levels (P < 0.01). Medium GH was identical to authentic pituitary GH, as demonstrated by high pressure liquid chromatography. RT-PCR of hypothalamic hormone receptor messenger RNA in the mass revealed somatostatin receptor subtypes 2, 3, and 5 and GHRH, TRH, and dopamine receptor expression. No GH gene amplification, rearrangement, or gsp mutation was found. RB gene deletion and H-ras mutations, previously reported in PRL- and ACTH-secreting carcinomas, were not detected. In conclusion, clinical and molecular features of a GH-secreting pituitary carcinoma are presented. This metastatic lesion synthesized GH and expressed functional hypothalamic hormone receptors.

Acromegaly↗
PubMed1982

Nuclear imaging in the pediatric acute scrotum.

The acute scrotum in the pediatric patient frequently presents a diagnostic dilemma for even the most experienced clinician. In an effort to improve testicular salvage in equivocal cases, immediate surgical intervention has been recommended, despite a large number of unnecessary explorations. Evaluating the sodium pertechnetate Tc 99m radioisotopic scan in 46 boys, we found this study to be a rapid, reliable, sensitive, and noninvasive test that allows the selection of those patients who require immediate surgical intervention.

Adolescent↗
PubMed1981

High-risk thyroid cancer. Prolonged survival with early multimodality therapy.

Eleven patients with high-risk thyroid carcinoma of anaplastic or mixed anaplastic-differentiated histology were treated using an early multimodality approach. Patients were classified using the prognostic index for thyroid carcinoma developed by the EORTC. Therapy consisted of a four-drug chemotherapy combination, radioiodine (131I), and Bacille-Calmette-Guerin (BCG) immunotherapy. Treatment was designed to maximize effects against both anaplastic and differentiated tumor components. There has been prolonged disease-free survival (14+ to 73+ months) in patients with clear cell, small cell, and mixed anaplastic histologies. Currently five patients have been in complete remission for over 4 years. Treatment has been well tolerated. The long-term participation in care by a multispecialty team has produced promising results which we hope can be valuable as a basis for multicenter trials.

Adult↗
PubMed1979

Radioiodine in the treatment of medullary carcinoma of the thyroid.

Medullary carcinoma (MC) of the thyroid, in contrast to papillary-follicular carcinoma, fails to concentrate iodine and thus has not been treated with radioactive iodine. We have successfully treated a 16-yr-old Mexican-American girl with residual MC after maximal thyroidectomy (Tx), utilizing radioiodine (131I) to deliver radiation to residual follicular cells in the tumor bed. Immediately after Tx, plasma thyrocalcitonin levels before and during calcium infusion were all elevated (640--1200 pg/ml). 131I (150 mCi) was administered 12 days after Tx after four daily im injections of bovine TSH. Three months after 131I therapy, thyrocalcitonin levels before and during calcium infusion were all normal (less than 50 pg/ml). Ten months after 131I therapy, thyrocalcitonin levels before and after iv pentagastrin were all normal (less than 60 pg/ml). These results suggest that parafollicular cells are radiosensitive, and that therapeutic levels of radiation can be delivered to these cells after Tx if iodine trapping by the remaining follicular cells is enhanced by high levels of circulating TSH. 131I may be the therapy of choice for MC after Tx, if disease has not spread beyond the area proximate to the thyroid gland.

Adolescent↗
PubMed1977

Thermographic, radionuclide, and radiographic detection of bone metastases.

The sensitivity of thermography to osseous metastases is compared to 99mTc bone scanning using the specificity of radiographic skeletal survey as proof of metastases. Thirty-five patients with suspected disease were selected for study. Bone scans detected 94.4% while thermograms detected 22.2%. Thermography proved quite insensitive to osseous metastases. Radionuclide bone scanning is the method of choice for the present.

Bone Neoplasms↗