I. Ross McDougall

Thyroid dysfunction after radiotherapy in children with Hodgkin's disease

Thyroid function was measured in 119 children, 16 years of age or less, after radiotherapy (XRT) for Hodgkins disease. Thyroid abnormalities developed in 4 of 24 children (17%) who received 2600 red or less, and in 74 of 95 children (78%) who received greater than 2600 rad to the cervical area, including the thyroid. The abnormality in all but three (one with hyperthyroidism and two with thyroid nodules) included the development of elevated levels of thyroid stimulating hormone (TSH). Age, sex, and administration of chemotherapy were not significant factors in the development of thyroid dysfunction. All children had lymphangiograms (LAG) and no time relationship was noted between thyroid dysfunction and LAG‐XRT interval. The mean interval from radiotherapy to documented thyroid dysfunction was 18 months in the low‐dose group and 31 months in the high‐dose group, with most patients becoming abnormal within 3 to 5 years. Of interest was a spontaneous return of TSH to within normal limits in 20 children and substantial improvement in another 7. This study confirms the occurrence of dose‐related occult hypothyroidism in children following external irradiation of the neck.

Hyperthyroxinemia in patients with acute psychiatric disorders

Thyroid function tests were measured in 645 patients admitted to an acute psychiatric disorders unit. Thirty-three percent had elevated serum thyroxine (T4), and 18 percent had an elevated free T4 index (FTI). Serum triiodothyronine (T3) was low, normal, or minimally elevated in 77 patients, with a high initial free T4 index. Twenty-two patients with an initial elevation of their free T4 index were serially followed (study group). Serum T4, free T4 index, and free T4 fell in every patient: serum T4 from 13.95 +/- 1.93 micrograms/dl (mean +/- standard deviation: SD) to 9.33 +/- 2.4 micrograms/dl (p less than 0.001); free T4 index, from 6.15 +/- 0.83 to 3.79 +/- 1.1 (p less than 0.001); free T4, from 2.43 +/- 0.65 mg/dl to 1.38 +/- 0.35 ng/dl (p less than 0.001). Serum T3 was initially normal or low, and then fell in 17 patients, and rose in five. Serial testing of thyrotropin-releasing hormone (TRH) demonstrated both flat and normal responses in patients with a variety of psychiatric diagnoses and at varying stages of thyroid disease activity.

Thyroid carcinoma after high-dose external radiotherapy for Hodgkin's disease. Report of three cases

Three patients (two female and one male), who had received mantle irradiation for Hodgkins disease eight, ten, and twelve years previously, developed papillary thyroid carcinoma. The radiation doses to the necks overlying the site of thyroid cancers were 3000, 4000, and 4100 rads, respectively, It has been stated that there is no risk of developing thyroid cancer with such high doses of external irradiation but apparently this complication will be encountered in a small number of patients.

F-18 FDG PET/CT in the management of thyroid cancer.

Purpose: There are approximately 32,000 new cases of thyroid carcinoma annually in the United States. F-18 FDG PET/CT has an established role in cancer management, including thyroid cancer, usually in patients who are thyroglobulin (Tg) positive/iodine negative. We reviewed our experience with F-18 FDG PET/CT in thyroid cancer, with an emphasis on correlation with Tg, and maximum standardized uptake values (SUV). We also analyzed the role of thyroid stimulating hormone (TSH) on PET/CT results. Materials and Methods: This is a retrospective study (January 2003 to December 2006) of 76 patients with differentiated thyroid cancer, who had F-18 FDG PET/CT scans. There were 44 women and 32 men, with age range of 20 to 81 years (average, 51.1 ± 18.1). The administered doses of F-18 FDG ranged from 396 to 717 MBq (15.8–19.4 mCi) (average, 566 ± 74.8) (15.3 ± 2). Reinterpretation of the imaging studies for accuracy and data analysis from medical records were performed. Results: A total of 98 PET/CT scans were analyzed (59 patients had 1 scan, 12 patients had 2, and 5 patients had 3). PET/CT was 88.6% sensitive (95% CI: 78.–94.3) and 89.3% specific (95% CI: 71.9–97.1). Mean Tg level was 1203 ng/mL (range, 0.5–28,357) in patients with positive PET/CT and 9.72 ng/mL (range, 0.5–123.0) in patients with negative PET/CT scans (P = 0.0389). Mean SUV max was 10.8 (range, 2.5–32) in the thyroid bed recurrence/residual disease and 7.53 (range, 2.5–26.2) in metastatic lesions (P = 0.0114). Mean SUV max in recurrent/residual disease in patients with TSH ≤30 mIU/L was 9.3 (range, 2.5–34.1) and in patients with TSH >30 mIU/L was 8.1 (range, 2.6–32) (P = 0.2994). Conclusion: F-18 FDG PET/CT had excellent sensitivity (88.6%) and specificity (89.3%) in this patient population. Metastatic lesions were reliably identified, but were less F-18 FDG avid than recurrence/residual disease in the thyroid bed. TSH levels at the time of PET/CT did not appear to impact the FDG uptake in the lesions or the ability to detect disease. In the setting of high or rising levels of Tg, our study confirms that it is indicated to include PET/CT in the management of patients with differentiated thyroid cancer.

Efficacy of 18F-FDG PET/CT in the evaluation of patients with recurrent cervical carcinoma

PurposeOnly a limited number of studies have evaluated the efficacy of 18F-FDG PET/CT for recurrent cervical carcinoma, which this study seeks to expand upon.MethodsThis is a retrospective study of 30 women with cervical carcinoma who had a surveillance PET/CT after initial therapy. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were calculated using a 2 × 2 contingency table with pathology results (76%) or clinical follow-up (24%) as the gold standard. The Wilson score method was used to perform 95% confidence interval estimations.ResultsThe sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT for the detection of local recurrence at the primary site were 93, 93, 93, 86, and 96%, respectively. The same values for the detection of distant metastases were 96, 95, 95, 96, and 95%, respectively. Seventy-one percent of the scans performed in symptomatic patients showed true-positive findings. In comparison, 44% of scans performed in asymptomatic patients showed true-positive findings. But, all patients subsequently had a change in their management based on the PET/CT findings such that the effect was notable. The maximum standardized uptake value ranged from 5 to 28 (average: 13 ± 7) in the primary site and 3 to 23 (average: 8 ± 4) in metastases which were significantly different (p = 0.04).ConclusionThis study demonstrates favorable efficacy of 18F-FDG PET/CT for identification of residual/recurrent cervical cancer, as well as for localization of distant metastases.

Treatment of orbital pseudotumor (idiopathic orbital inflammation) by radiation therapy

Abstract Orbital pseudotumor is a non-specific inflammatory condition which clinically may simulate a neoplasm. This report describes the Stanford University Medical Center experience with orbital radiotherapy in the treatment of five patients with orbital pseudotumor, three with bilateral involvement, two with unilateral lesions. Four patients with computed tomography (CT) scans had characteristic findings of pseudotumor; four had the diagnosis confirmed by biopsy. There was no evidence of an alternative diagnosis or systemic disease in any of the patients. Therapy consisted of 2000 rad of fractionated radiotherapy over 10 days with a 4 MeV linear accelerator. Each patient experienced dramatic and rapid improvement in symptoms and signs. Exophthalmometric measurements improved by 8, 8, 6, and 5 millimeters respectively in those with proptosis. There has been no recurrence after a mean follow up of 30 months and no complications of treatment. Orbital radiotherapy may be a preferable alternative to surgical or corticosteroid treatment for pseudotumor. Because of the variability in presentation, radiotherapy must be individualized so that orbital lesions are treated effectively while adjacent normal structures are shielded.

Needle track seeding of papillary thyroid carcinoma from fine needle aspiration biopsy. A case report.

BACKGROUND Dissemination of tumor cells from needle biopsy has been observed in a wide range of tumor types. Fine needle aspiration (FNA) biopsy has become accepted as the first-line test in the evaluation of thyroid nodules. Local recurrence of thyroid cancer from needle track seeding is an extremely rare complication of thyroid FNA. CASE A 59-year-old woman developed local recurrence of papillary thyroid carcinoma three years after FNA of the primary cancer. Local metastases developed in the skin and sternocleidomastoid muscle. The location of the recurrent cancer and the linear relationship of the metastases indicated that local recurrence was due to needle track seeding at the time of FNA. CONCLUSION Needle track seeding has been recognized as a possible, albeit rare, complication of FNA of thyroid cancer. Although proper FNA technique can reduce the potential for needle track seeding, its occurrence is an unavoidable complication of FNA evaluation of thyroid malignancies.

Serum free thyroxine values in term, premature, and sick infants

Free thyroxine concentrations were determined by radioimmunoassay in 96 infants within an intensive care nursery and in 32 healthy term infants. Sera for free T4 levels were drawn simultaneously with the filter paper specimens for T4 obtained to screen these infants for congenital hypothyroidism. The mean free T4 level in 20 adults was 1.38 +/- 0.03 ng/dl (mean +/- SEM). The mean in the ICN infants was 3.48 +/- 0.18 ng/dl and in healthy term infants, 4.24 +/- 0.23 ng/dl. Like T4, free T4 correlated positively with increasing gestational age and birth weight, and was lower in infants with RDS. Although 66% of the ICN infants had T4 levels below the statistically selected screening level (fifth percentile), all of these infants had free T4 levels greater than 0.8 ng/dl. Two additional infants with untreated congenital hypothyroidism has free T4 levels of 0.3 and 0.4 ng/dl. The measurement of free T4 appears to be an accurate indicator of thyroid function in these infants.

How frequently is the thymus seen on whole-body iodine-131 diagnostic and post-treatment scans?

Abstract.The purpose of the study was to determine how often the thymus is visualized on whole-body radioiodine scans. One hundred and seventy-five patients had 325 diagnostic scans and 200 post-treatment scans. Activity in the mediastinum possibly consistent with the thymus was seen on seven scans in six patients. Four of these were diagnostic scans (three were second follow-up scans, and the fourth, a third follow-up scan). Three post-treatment scans demonstrated mediastinal uptake. Only one patient had persistent mediastinal uptake on both a post-treatment scan and a subsequent follow-up diagnostic scan. None of these six patients were treated as a result of this finding and none has clinical or biochemical evidence of metastatic disease.

Thyroid Stunning: Fact or Fiction?

Stunning of thyroid tissue by diagnostic activities of (131)I has been described by some investigators and refuted by others. The support both for and against stunning has at times been enthusiastic and vigorous. We present the data from both sides of the debate in an attempt to highlight the strengths and deficiencies in the investigations cited. Clinical, animal, and in vitro studies are included. There are considerable differences in clinical practice, such as the administered activity for diagnostic whole-body scan, delay between diagnostic scan and treatment, time between treatment and posttherapy scanning, and timing of follow-up studies, that have to be analyzed with care. Other factors that often cannot be judged, such as levels of thyroid-stimulating hormone and serum iodine at time of diagnostic testing versus treatment could have an influence on stunning. Larger diagnostic doses and longer delays to therapy appear to increase the likelihood of stunning. The stunning effect of early-absorbed radiation from the therapy should also be considered.