Subclinical thyroid disease after radiation therapy detected by radionuclide scanning.

PURPOSE: The actuarial risk for developing benign or malignant thyroid disease following radiation therapy (RT) is controversial, but may be as high as 50% at 20 years. An effective screening modality should be specific but not overly sensitive, a limitation of ultrasound. We questioned whether Technetium-99 m pertechnetate ((99m)Tc TcO(4)(-)) scanning could detect clinically significant disease in ostensibly disease-free cancer survivors. METHODS AND MATERIALS: Eligibility criteria included an interval of at least 5 years after RT to the cervical region, a thyroid gland that was normal to palpation, euthyroid status determined by clinical examination, free T4 and TSH. The 34 patients scanned included 16 children (<18 years old) and 18 adults at the time of RT, 16 females and 18 males. The mean age at RT was 20 years (range, 2.1-50.3 years), and the mean age at (99m)Tc TcO(4)-scanning was 33 years (range, 13.6-58 years), providing a mean interval of 13 years (range, 5.3-26.6 years). The mean RT dose to the thyroid was 36.4 Gy (range, 19.5-52.5). Thyroid scanning was performed with a 5 mCi dose of (99m)Tc TcO(4)(-) obtaining flow, immediate and delayed static, and pinhole collimator images. RESULTS: Seven patients (21.6%) had abnormal scans, and the percentage was higher among children (25%) and females (25%) compared to adults (16.7%) and males (16.7%), respectively. Two of 34 patients (5.9%) were discovered to have a thyroid cancer; histopathologies were papillary and follicular carcinoma. CONCLUSION: In this population of clinically normal cancer survivors who had been irradiated to the cervical region, subclinical thyroid disease, of potential clinical significance, was detected by (99m)Tc TcO(4)(-) in about 20%. Children may be more commonly affected. Although the cost effectiveness of screening will require a larger sample number, we propose a surveillance schema for this patient population.

Absence of thyroid stunning after diagnostic whole-body scanning with 185 MBq 131I.

UNLABELLED: There has been recent controversy regarding the optimal protocol for imaging and ablation of post-thyroidectomy patients. Several authors have suggested that a scanning dose of 185-370 MBq (5-10 mCi) (131)I may be capable of producing a stunning effect on thyroid tissue that may interfere with the uptake and efficacy of the subsequent ablation dose of radioiodine. The purpose of this study was to determine whether a 185-MBq (5 mCi) diagnostic dose of (131)I produces a visually apparent stunning effect 72 h before (131)I ablation therapy. METHODS: One hundred twenty-two consecutive post-thyroidectomy patients for differentiated thyroid carcinoma received a 185-MBq (5 mCi) diagnostic dose of (131)I followed by a whole-body diagnostic scan at 72 h. On the same day the diagnostic scan was completed, the patient was admitted to the hospital and received an (131)I ablation therapy dose of 5550 MBq (150 mCi) in most cases. A postablation, whole-body scan was obtained at 72 h and compared with the previous diagnostic scan for any visual evidence of stunning. RESULTS: No cases of visually apparent thyroid stunning were observed on any of the postablation scans with regard to the number of (131)I foci identified or the relative intensity of (131)I uptake seen. CONCLUSION: Diagnostic whole-body scanning can be performed effectively with a 185-MBq (5 mCi) dose of (131)I 72 h before radioiodine ablation without concern for thyroid stunning.

Urine leaks in renal transplant patients. Diagnostic usefulness of sonography and renography.

We evaluated the utility of sonography and nuclear medicine renography in the detection of urine leaks in 57 renal transplant patients. Sonography and renography were equally sensitive in detecting leaks. But renography was more specific and therefore accurate (p < 0.0001) in detecting leaks. Urine leaks should be considered on sonography, which is often the first imaging study ordered in evaluating renal transplants, with new or increasing peritransplant fluid collections. Leaks should be confirmed by renography before performing additional invasive radiologic or surgical procedures.

Renography before heart transplantation in patients with cardiomyopathy.

UNLABELLED: In patients with ischemic cardiomyopathy (CM), abnormal renograms may result not only from circulatory failure (which should reverse after transplantation) but also from intrinsic renal disease (which contraindicates heart transplantation). Here, the outcome of heart transplantation was related to preoperative renograms, and the differentiating and prognostic value of renography was analyzed. METHODS: The study population consisted of 50 patients with ischemic CM expecting heart transplantation. Anatomical renal pathology was excluded in all patients. Dynamic renal scintigraphy was performed with 99mTc-mercaptoacetyltriglycine. Background-subtracted renograms were inspected visually and characterized numerically. Mean parenchymal transit time (mPTT), renal tracer content at 15 min (RTC15) and retention index (RI) were determined. The parametric renogram values were related to a normal reference group of 64 patients. The preoperative renograms were matched with the postoperative outcome. RESULTS: Three characteristic types of symmetrical findings in the kidneys were found: no pathological findings, mildly delayed peak and excretion phase and severely delayed peak and excretion phase. Pathological renograms were observed in 36 of 50 (72%) patients. The mean parametric renogram values in ischemic CM were as follows: Group A (normal kidney function), mPTT = 142+/-26.6 sec, RTC15 = 22.3%+/-4.6% and RI = 24.7+/-11.9; Group B (mild dysfunction), mPTT = 210+/-44.0 sec, RTC15 = 42.6%+/-10.3% and RI = 101.4+/-50.5; Group C (severe dysfunction), mPTT = 320+/-94.2 sec, RTC15 = 79.6%+/-15.9% and RI = 347.7+/-194.7; and reference patients (normal kidney function), mPTT = 137+/-31.1 sec, RTC15 = 22.8%+/-3.8% and RI = 24.6+/-7.9. Postoperative serum creatinine levels were <1.5 mg/dl in all Group A patients, between 1.5 and 2.5 mg/dl in 78% of Group B patients and >2.5 mg/dl in 75% of Group C patients. CONCLUSION: Renography revealed abnormal kidney function when structural pathology was excluded. The renographic abnormalities in ischemic CM did not reflect simply the circulatory failure. The numerical grading of renograms allowed patient stratification, suggestive of possible renal insufficiency after cardiac transplantation and immunosuppressive therapy. With further experience, renography may become a useful tool for predicting postoperative outcome in ischemic CM.

Thyroglossal duct cyst with papillary carcinoma in an 11-year-old girl.

A case of primary papillary carcinoma arising in a thyroglossal duct cyst is reported in a young girl. This is a rare finding, with only five pediatric cases in the total of 115 cases reported in the literature. Subsequent management is described, including the role of scintigraphy and radioiodine ablation.

The clinical utility of quantitative cholescintigraphy: the significance of gallbladder dysfunction.

PURPOSE: Cholelithiasis is a common disorder occurring in over 20 million people in the United States and resulting in approximately 600,000 cholecystectomies annually. Although over 95% of biliary tract disease is caused by gallstones, the vast majority (>80%) of cholelithiasis cases are asymptomatic. The purpose of this study is to evaluate the utility of quantitative cholescintigraphy in detecting symptomatic biliary tract disease and predicting clinical relief after cholecystectomy. MATERIALS AND METHODS: Fifty-two patients with clinical symptoms of chronic cholecystitis were evaluated by cholescintigraphy with a gallbladder ejection fraction calculated after the intravenous administration of cholecystokinin. A gallbladder ejection fraction of > or =35% was considered a normal physiologic response. Forty-one of the patients subsequently underwent cholecystectomy, whereas the remaining 11 subjects were diagnosed and treated for non-biliary disorders that did not require cholecystectomies. After clinical follow-up including histopathological gallbladder findings, all subjects' final diagnoses were established and correlated with their quantitative cholescintigram study. RESULTS: Twenty-six of twenty-eight patients who had an abnormal quantitative cholescintigram demonstrated evidence of chronic cholecystitis by histopathologic criteria after cholecystectomy. Furthermore, 27 of these 28 patients (96%) experienced complete relief of their clinical symptoms after surgery. CONCLUSION: Functional cholescintigraphy is a safe, accurate, and useful test for detecting symptomatic gallbladder disease, and appears reliable in predicting symptomatic relief after cholecystectomy.

Magnetic resonance imaging: a cost-effective alternative to bone scintigraphy in the evaluation of patients with suspected hip fractures.

OBJECTIVE: To evaluate the cost-effectiveness of magnetic resonance imaging (MRI) compared with radionuclide bone scan in the evaluation of patients with clinically suspected hip fractures. DESIGN: The medical records of all patients who had been seen in the emergency room over a 4 1/2 year period with a clinically suspected hip fracture, negative or equivocal plain films, and either a subsequent bone scan or MRI examination were retrospectively reviewed. The time to diagnosis, admission rate, and time to surgery were determined. A two-sample t-test was used to assess the statistical significance of the results. A theoretical cost analysis was performed using current charges to estimate all expenses. PATIENTS: Forty patients (11 male, 29 female; age 28-99 years) satisfied our inclusion criteria. RESULTS AND CONCLUSIONS: Twenty-one patients had bone scans (six with fractures), and 19 had MRI (four with fractures). The time to diagnosis was 2.24 +/- 1.30 days for bone scanning and 0.368 +/- 0.597 days for MRI (P < 0.0001). Twenty patients in the bone scan group were admitted compared with 13 in the MRI group. The time to surgery was at least 1 day longer in patients undergoing bone scanning. Bone scanning resulted in higher patient costs compared with MRI because of the delay in diagnosis. In the evaluation of patients with suspected hip fractures, early MRI is more cost-effective than delayed bone scanning. Further prospective studies comparing the cost-effectiveness of early MRI with early bone scanning are needed.

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.

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.

Ablation of remaining functioning thyroid lobe with radioiodine after hemithyroidectomy for carcinoma.

Nineteen patients who had hemithyroidectomy as a surgical procedure for thyroid cancer were given radioiodine to ablate the residual hemithyroid. Two different protocols were used, with either a larger single dose or multiple smaller doses. Ablation was achieved in 28% with the single large dose approach and in 33% of patients given split doses of similar total amount. This response to the initial attempt at eradication of the residual normal hemithyroid is considerably lower than the accepted ablation rate with comparable doses administered to patients with small thyroid residues after total thyroidectomy. It is suggested that the effect of radioiodine treatment may relate inversely to the size of the thyroid remnant. Our findings also are in support of the surgical approach advocating total thyroidectomy for patients contemplating ablation of thyroid residues after surgery for thyroid carcinoma.

Gastric uptake of Tc-99m MDP in a child treated with isotretinoin.

The side effects of prolonged isotretinoin therapy include progressive calcification of ligamentous and tendon insertions, premature fusion of epiphyses, and modeling abnormalities of long bones. Increased calcification of gastric mucosa has been reported only in animal studies, but not in humans. A case of a child who was treated with isotretinoin for 26 months for a dermatologic disorder and who showed abnormal gastric uptake of 99m-Tc MDP on a bone scan is reported.

Fractionated doses of radioiodine for ablation of postsurgical thyroid tissue remnants.

Patients who have differentiated thyroid carcinoma and have undergone total thyroidectomy are treated with radioiodine for ablation of functional thyroid remnants. Administration of a single therapeutic dose in excess of 30 mCi of l-131 requires hospitalization. In an attempt to obviate the necessity for hospitalization, the prospective ablative dose was divided into two or three fractions given at weekly intervals on an ambulatory basis. To assess the effectiveness of this approach, this group of patients was compared to a cohort of hospitalized patients treated with a single dose. Ablation was achieved in 9 out of 12 patients treated in a fractionated manner (a 75% success rate), whereas in 16 out of 20 patients given a single dose the thyroid remnants were completely eradicated (an 80% success rate). That the use of split, smaller doses administered at weekly intervals on an ambulatory basis presents a reasonable alternative for ablation of postsurgical, residual-functioning thyroid tissue.