Radionuclide diagnosis and therapy of thyroid cancer: current status report

Ultrasonographic Features of Salivary Glands after Radioiodine Therapy in Patients with Thyroid Cancer

OBJECTIVE

Chronic sialadenitis is the most common complication of radioactive iodine (RAI) treatment. The aim of the study was to ascertain sonographic features of the major salivary glands in patients with papillary thyroid cancer (PTC) treated with RAI.

METHODS

The database of a tertiary medical center was retrospectively searched for consecutive patients who underwent total thyroidectomy for PTC in 2011-2020 with ultrasound follow-up after 1 year. Changes in ultrasound features of the major salivary glands were compared between patients treated or not treated with RAI postoperatively.

RESULTS

The cohort included 158 patients, of whom 109 (69%) were treated postoperatively with RAI (mean dose, 131 mCi) and 49 were not (control group). Sonographic changes were observed in the major salivary glands in 43% of the study group and 18% of the control group (p = 0.002), including coarse echotexture, decreased echogenicity, fibrosis, and atrophy. Higher RAI doses were significantly correlated with the prevalence and severity of glandular changes (p < 0.0001).

CONCLUSION

RAI treatment following thyroidectomy is associated with a dose-response effect and adverse changes in the major salivary glands and should be prescribed carefully.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:1271-1275, 2023.

Radioiodine therapy induced sialadenitis versus chronic idiopathic sialadenitis-Presentation and outcomes

BACKGROUND

This study explores the unique characters of high dose radioactive iodine (RAI) induced chronic sialadenitis.

METHODS

A retrospective study of patients having received salivary endoscopy and followed in our outpatient clinic.

RESULTS

A total of 100 patients met the inclusion criteria, 75 were diagnosed with chronic idiopathic sialoadenitis and 25 with radio-iodine induced sialoadenitis (RIS). The main complaint in both groups was swelling of the parotid gland. Pain, dysphagia, and xerostomia were observed considerably more in the RIS group. During sialo-endoscopy, fibrosis of the Stensen's duct was more common in the RIS group (p = 0.003). RIS patients group generally managed better with interventional endoscopic treatment alone (80% vs. 46%).

CONCLUSION

RIS patients have distinct clinical characteristics. There may be a collateral muscular damage to the masticatory muscles. Fibrosis and parenchymal damage are major findings during sialendoscopy. Sialendoscopy is a safe and efficient treatment for RAI induced sialadenitis.

Hyperthyroidism and Concurrent Thyroid Cancer

Aims and Background

The aim of this study was to analyze the frequency of coexisting hyperthyroidism and thyroid malignancy in endemic goiter areas and review the current literature on the subject.

Methods

During the period January 1984 to June 1998, 1853 patients were examined for hyperthyroidism at the Spedali Civili Hospital of Brescia, Italy; 512 (27.6%) subjects underwent surgery. Of these patients 108 (21%) had Graves’ disease, 251 (49%) multinodular toxic goiter (MTG) and 153 (30%) uninodular toxic goiter (UTG).

Results

Malignancy was found in 24 (4.7%) patients: 19 females and 5 males with a mean age of 52.2 years (range, 21-76 years). The frequency of cancer in Graves’ disease was 6.4%, 5 females and 2 males; in MTG 3.9%, 2 females and 8 males, and in UTG 4.4%, 7 females and 1 male.

Conclusions

Our data confirm previous reports on the frequency of thyroid cancer in hyperthyroidism. This association is more relevant than previously suspected. The frequent coexistence of hyperthyroidism and neoplasia, demonstrated by our study and the most recent literature, underlines the importance of studying and excluding the possibility of neoplastic degeneration by means of a systematic approach.

Favorable Long Term Results in Patients with Small Differentiated Thyroid Cancer not Treated with Radioiodine

Data on a group of 110 patients with differentiated thyroid cancer not treated by radioiodine are reported. Most of them had intrathyroid (stage I) papillary or capsuled follicular cancer of less than 3 cm diameters. They all received thyroxine at TSH suppressive doses. The follow-up ranged between 4 and 25 years, mean 8.7. No patient died of tumor. Two very old patients died free of disease. Four recurrences occurred, within 8 years, all in patients over 45 years, all local or nodal, all papillary, 3 out of 4 after total thyroidectomy. This study shows that radioiodine therapy may be avoided and that lobectomy may be sufficient in patients under 45 years with small papillary or capsuled follicular cancer.

Tumor-Absorbed Dose for Non-Hodgkin Lymphoma Patients Treated with the Anti-CD37 Antibody Radionuclide Conjugate 177Lu-Lilotomab Satetraxetan

¹⁷⁷Lu-lilotomab satetraxetan is a novel antibody radionuclide conjugate currently tested in a phase 1/2a first-in-human dosage escalation trial for patients with relapsed CD37+ indolent non-Hodgkin lymphoma. The aim of this work was to develop dosimetric methods and calculate tumor-absorbed radiation doses for patients treated with ¹⁷⁷Lu-lilotomab satetraxetan.

METHODS

Patients were treated at escalating injected activities (10, 15 and 20 MBq/kg) of ¹⁷⁷Lu-lilotomab satetraxetan and with different predosing, with or without 40 mg of unlabeled lilotomab. Eight patients were included for the tumor dosimetry study. Tumor radioactivity concentrations were calculated from SPECT acquisitions at multiple time points, and tumor masses were delineated from corresponding CT scans. Tumor-absorbed doses were then calculated using the OLINDA sphere model. To perform voxel dosimetry, the SPECT/CT data and an in-house-developed MATLAB program were combined to investigate the dose rate homogeneity.

RESULTS

Twenty-six tumors in 8 patients were ascribed a mean tumor-absorbed dose. Absorbed doses ranged from 75 to 794 cGy, with a median of 264 cGy across different dosage levels and different predosing. A significant correlation between the dosage level and tumor-absorbed dose was found. Twenty-one tumors were included for voxel dosimetry and parameters describing dose-volume coverage calculated. The investigation of intratumor voxel doses indicates that mean tumor dose is correlated to these parameters.

CONCLUSION

Tumor-absorbed doses for patients treated with ¹⁷⁷Lu-lilotomab satetraxetan are comparable to doses reported for other radioimmunotherapy compounds. Although the intertumor variability was considerable, a correlation between tumor dose and patient dosage level was found. Our results indicate that mean dose may be used as the sole dosimetric parameter on the lesion level.

Salivary gland dysfunction after radioactive iodine (I-131) therapy in patients following total thyroidectomy: emphasis on radioactive iodine therapy dose

PURPOSE

The purpose of this study was to retrospectively evaluate symptoms, images of salivary gland dysfunction, and related clinical factors in thyroid cancer patients with total thyroidectomy followed by radioiodine therapy (RIT).

METHODS

We included 164 patients who underwent thyroid ultrasonography or contrast-enhanced neck computed tomography more than 6 months later after RIT. Correlation between subjective symptoms and various RIT doses was also evaluated.

RESULTS

Swelling and decreased salivary volume were the most common symptoms and images. RIT dose was the only factor with a positive correlation (P<.001).

CONCLUSION

The dose of RIT should be carefully determined to minimize gland dysfunction.

Stimulated Serum Thyroglobulin Level at the Time of First Dose of Radioactive Iodine Therapy Is the Most Predictive Factor for Therapeutic Failure in Patients With Papillary Thyroid Carcinoma

PURPOSE

To investigate the clinical importance of serum thyroglobulin (Tg) levels just before high-dose I-131 ablation therapy (preablation Tg) for predicting therapeutic failure in patients with papillary thyroid carcinoma (PTC).

METHODS

Patients with PTC (n = 132) undergoing total thyroidectomy followed by the first high-dose I-131 ablation therapy (HI-Rx) were included in this retrospective review. Just before HI-Rx, preablation Tg, anti-Tg antibody, and TSH were measured. The patients were followed up for a mean period of 7 months (range 6-23 months) by I-123 whole-body scans (f/u IWBS) and stimulated Tg (f/u Tg). Therapeutic failure was defined by positive f/u IWBS or f/u Tg >2 ng/ml. We classified patients into three groups according to the value of preablation Tg (group 1, <1 ng/ml; group 2, ≥1 and <10 ng/ml; group 3, ≥10 ng/ml) and compared clinical variables to therapeutic response.

RESULTS

Therapeutic failure was noted in 39 patients (29.5 %). On univariate analysis, T stage, tumor size, and preablation Tg were the statistically significant factors that could predict therapeutic failure. After multivariate analysis, preablation Tg was the only independent predictor of therapeutic failure (P < 0.001). The therapeutic failure rate was significantly increased as the preablation Tg level increased (11.3 %, 33.3 %, and 87.5 % in groups 1, 2, and 3, respectively; P < 0.001). Individuals with preablation Tg levels ≥10 ng/ml had 25.5 times greater chance of therapeutic failure than those with levels <10 ng/ml (95 % CI = 5.43-119.60; P < 0.001).

CONCLUSIONS

A high preablation Tg level is the most significant predictor of therapeutic failure at the time of first HI-Rx in patients with PTC.

Sialoendoscopy: a viable treatment for I(131) induced sialoadenitis

To evaluate the viability, efficacy, and safety of sialoendoscopy for the diagnosis and management of radioiodine I(131-) related sialoadenitis, we retrospectively reviewed 30 patients referred between September 2007 and July 2013 from the Thyroid Surgery Unit to the Maxillofacial Unit of the Second University of Naples Hospital with persistent sialoadenitis after treatment with I(131). After the affected gland had been isolated, the endoscope was introduced into the duct under local anaesthesia with 2% lignocaine and continuous lavage with isotonic saline, and was advanced until it reached the ductal system. We studied 24 women and 6 men, mean (SD) age 52 (??) years. In 25 patients I(131) was given for papillary (83%), in 3 for medullary (10%), and in 2 for follicular thyroid carcinoma (7%). Stenosis alone was found in 30 glands (40%), mucous plugs alone in 35 (47%), and mucous plugs, stenosis, and kinks in 10 (13%). Of the 75 glands, dilatation of the ducts was successful in 70, and we completely removed all mucous plugs and kinks. We achieved symptomatic improvement in 23 patients (77%) during a follow-up ranging from 2 weeks to 84 months. Sialoendoscopy is a viable technique for the diagnosis of obstructive salivary disease, and is a safe and effective way to treat sialoadenitis, the most common complication of treatment with I(131).

Targeting breast carcinoma with radioiodinated anti-HER2 Nanobody

INTRODUCTION

With a molecular weight an order of magnitude lower than antibodies but possessing comparable affinities, Nanobodies (Nbs) are attractive as targeting agents for cancer diagnosis and therapy. An anti-HER2 Nb could be utilized to determine HER2 status in breast cancer patients prior to trastuzumab treatment. This provided motivation for the generation of HER2-specific 5F7GGC Nb, its radioiodination and evaluation for targeting HER2 expressing tumors.

METHODS

5F7GGC Nb was radioiodinated with ¹²⁵I using Iodogen and with ¹³¹I using the residualizing agent N(ɛ)-(3-[¹³¹I]iodobenzoyl)-Lys⁵-N(α)-maleimido-Gly¹-GEEEK ([¹³¹I]IB-Mal-D-GEEEK) used previously successfully with intact antibodies. Paired-label internalization assays using BT474M1 cells and tissue distribution experiments in athymic mice bearing BT474M1 xenografts were performed to compare the two labeled Nb preparations.

RESULTS

The radiochemical yields for Iodogen and [¹³¹I]IB-Mal-D-GEEEK labeling were 83.6±5.0% (n=10) and 59.6±9.4% (n=15), respectively. The immunoreactivity of labeled proteins was preserved as confirmed by in vitro and in vivo binding to tumor cells. Biodistribution studies showed that Nb radiolabeled using [¹³¹I]IB-Mal-D-GEEEK, compared with the directly labeled Nb, had a higher tumor uptake (4.65±0.61% ID/g vs. 2.92±0.24% ID/g at 8h), faster blood clearance, lower accumulation in non-target organs except kidneys, and as a result, higher concomitant tumor-to-blood and tumor-to-tissue ratios.

CONCLUSIONS

Taken together, these results demonstrate that 5F7GGC anti-HER2 Nb labeled with residualizing [¹³¹I]IB-Mal-D-GEEEK had better tumor targeting properties compared to the directly labeled Nb suggesting the potential utility of this Nb conjugate for SPECT (¹²⁹I) and PET imaging (¹²⁴I) of patients with HER2-expressing tumors.

I-131 SPECT/CT elucidates cryptic findings on planar whole-body scans and can reduce needless therapy with I-131 in post-thyroidectomy thyroid cancer patients

BACKGROUND

Interpreting I-131 whole-body scans (WBSs) after thyroidectomy for thyroid cancer is not simple. There are scans in which interpretation is speculative because of cryptic findings (CF). Complexity is added in scans that are done a week after an ablative or therapeutic dose of I-131 because not only is I-131-labeled thyroxine (T4) distributed throughout the body, but inorganic I-131 that is derived from the de-iodination of T4 may be also detected. We present our observations regarding the analysis of CF on WBS using I-131 single-photon emission computed tomography (SPECT) in fusion with noncontrast computed tomography (CT), referred to here and elsewhere as I-131 SPECT/CT.

METHODS

Forty of 184 WBSs in 38 thyroidectomized thyroid cancer patients were followed up with I-131 SPECT/CTs. The SPECT/CT images were acquired after a tracer dose of I-131 (n=82) or a week after an ablative or therapeutic dose of I-131 (n=102).

RESULTS

Among 184 WBSs, 40 (22%) had CF. In 35 patients the WBS was negative for metastatic disease except for the CF and 5 patients had evidence of thyroid cancer in addition to the CF. There were 49 CF in the planar scans that were localized by SPECT/CT. These were characterized as physiological uptake in gingiva, thymus, gall bladder, menstrual blood, uterine fibroid, recto-sigmoid, colon, and bladder. Also observed was uptake in sites that represented nonthyroidal pathology including dental abscess, hiatal hernia, renal cyst, and struma ovarii. SPECT/CT suggested that 10 of the CF were actually of thyroid origin. In 40 SPECT/CT scans, the images contributed to interpreting the scan. In 15 of 40 patients the SPECT/CT analysis of WBS was performed with tracer doses of I-131 and was important for determining whether to administer ablative I-131 treatment. In another 25 patients, in whom SPECT/CT was performed after ablative or therapeutic doses of 131-I, information regarding the characterization of CF by SPECT/CT was useful in determining if thyroid cancer metastases or thyroid remnants were present.

CONCLUSIONS

I-131 SPECT/CT is a useful tool to characterize atypical or CF on WBS by differentiating thyroid remnant or cancer from physiologic activity or nonthyroid pathology. In the past, uptake on a WBS that was not explicable as physiologic activity was identified as putative or possible thyroid cancer and generally was treated with I-131. Now, by identifying activity in some possible cancer sites as not thyroid cancer, SPECT/CT can reduce inappropriate treatment with I-131. SPECT/CT of WBS performed after ablative doses of 131-I is useful in determining the nature of CF and therefore likely providing prognostic information.

RETRACTED ARTICLE: Radiation sialadenitis induced by high-dose radioactive iodine therapy

Radioactive iodine ((131)I) is accumulated in the thyroid tissue and plays an important role in the treatment of differentiated papillary and follicular cancers after thyroidectomy. Simultaneously, (131)I is concentrated in the salivary glands and secreted into the saliva. Dose-related damage to the salivary parenchyma results from the (131)I irradiation. Salivary gland swelling and pain, usually involving the parotid, can be seen. The symptoms may develop immediately after a therapeutic dose of (131)I and/or months later and progress in intensity with time. In conjunction with the radiation sialadenitis, secondary complications reported include xerostomia, taste alterations, infection, increases in caries, facial nerve involvement, candidiasis, and neoplasia. Prevention of (131)I sialadenitis may involve the use of sialogogic agents to hasten the transit time of the radioactive iodine through the salivary glands. However, studies are not available to delineate the efficacy of this approach. Treatment of the varied complications that may develop encompass numerous approaches and include gland massage, sialogogic agents, duct probing, antibiotics, mouthwashes, good oral hygiene, and adequate hydration. Recently interventional sialoendoscopy has been introduced an effective tool for the management of patients with (131)I-induced sialadenitis that is unresponsive to medical treatment.

Does amifostine have radioprotective effects on salivary glands in high-dose radioactive iodine-treated differentiated thyroid cancer

OBJECTIVES

To assess the effects of amifostine on salivary glands in radioactive iodine-treated differentiated thyroid cancer.

METHODS

We searched the MEDLINE, EMBASE and the Cochrane Library for randomized controlled clinical trials which compared the effects of amifostine with those of placebo or acid-stimulating agents.

RESULTS

Two randomized controlled clinical trials with a total of 130 patients were included. Both studies had a low risk of bias. There were no statistically significant differences between the effects of amifostine and acid-stimulating agents on the incidence of xerostomia (RR 0.24, 95% CI 0.01 to 9.52), the decrease of scintigraphically measured uptake of (99m)Tc by the parotid (RR 0.30, 95% CI -2.28 to 2.88) or submandibular glands (RR 1.90, 95% CI -1.46 to 5.26) at 12 months, or the reduction in blood pressure (RR 5.00, 95% CI 0.25 to 99.16). Neither of the included trials investigated death from any cause, morbidity, health-related quality of life or costs.

CONCLUSION

The results of two randomized controlled clinical trials suggest that amifostine has no significant radioprotective effects on salivary glands in radioactive iodine treatment of differentiated thyroid cancer. The use of acid-stimulating agents to increase salivation should remain the first choice during radioactive iodine treatment of differentiated thyroid cancer. Patients should also be well informed of the importance of hydration and acid stimulation.

Amifostine for salivary glands in high-dose radioactive iodine treated differentiated thyroid cancer

BACKGROUND

Radioactive iodine treatment for differentiated thyroid cancer possibly results in xerostomia. Amifostine has been used to prevent the effects of irradiation to salivary glands. To date, the effects of amifostine on salivary glands in radioactive iodine treated differentiated thyroid cancer remain uncertain.

OBJECTIVES

To assess the effects of amifostine on salivary glands in high-dose radioactive iodine treated differentiated thyroid cancer.

SEARCH STRATEGY

Studies were obtained from computerized searches of MEDLINE, EMBASE, The Cochrane Library and paper collections of conferences held in Chinese.

SELECTION CRITERIA

Randomised controlled clinical trials and quasi-randomised controlled clinical trials comparing the effects of amifostine on salivary glands after radioactive iodine treatment for differentiated thyroid cancer with placebo and a duration of follow up of at least three months.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risk of bias and extracted data.

MAIN RESULTS

Two trials with 130 patients (67 and 63 patients randomised to intervention versus control) were included. Both studies had a low risk of bias. Amifostine versus placebo showed no statistically significant differences in the incidence of xerostomia (130 patients, two studies), the decrease of scintigraphically measured uptake of technetium-99m by salivary or submandibular glands at twelve months (80 patients, one study), and the reduction of blood pressure (130 patients, two studies). Two patients in one study collapsed after initiation of amifostine therapy and had to be treated by withdrawing the infusion and volume substitution. Both patients recovered without sequelae. Meta-analysis was not performed on the function of salivary glands measured by technetium-99m scintigraphy at three months after high dose radioactive iodine treatment due to the highly inconsistent findings across studies (I(2) statistic 99%). None of the included trials investigated death from any cause, morbidity, health-related quality of life or costs.

AUTHORS' CONCLUSIONS

Results from two randomised controlled clinical trials suggest that the amifostine has no significant radioprotective effects on salivary glands in high-dose radioactive iodine treated differentiated thyroid cancer patients. Moreover, no health-related quality of life and other patient-oriented outcomes were evaluated in the two included trials. Randomised controlled clinical trials with low risk of bias investigating patient-oriented outcomes are needed to guide treatment choice.

Peptide-targeted radionuclide therapy for melanoma

Melanocortin-1 receptor (MC1-R) and melanin are two attractive melanoma-specific targets for peptide-targeted radionuclide therapy for melanoma. Radiolabeled peptides targeting MC1-R/melanin can selectively and specifically target cytotoxic radiation generated from therapeutic radionuclides to melanoma cells for cell killing, while sparing the normal tissues and organs. This review highlights the recent advances of peptide-targeted radionuclide therapy of melanoma targeting MC1-R and melanin. The promising therapeutic efficacies of 188Re-(Arg(11))CCMSH (188Re-[Cys(3,4,10), D-Phe(7),Arg(11)]-alpha-MSH(3-13)), 177Lu- and 212Pb-labeled DOTA-Re(Arg(11))CCMSH (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-[ReO-(Cys(3,4,10), D-Phe(7), Arg(11))]-alpha-MSH(3-13)) and 188Re-HYNIC-4B4 (188Re-hydrazinonicotinamide-Tyr-Glu-Arg-Lys-Phe-Trp-His-Gly-Arg-His) in preclinical melanoma-bearing models demonstrate an optimistic outlook for peptide-targeted radionuclide therapy for melanoma. Peptide-targeted radionuclide therapy for melanoma will likely contribute in an adjuvant setting, once the primary tumor has been surgically removed, to treat metastatic deposits and for treatment of end-stage disease. The lack of effective treatments for metastatic melanoma and end-stage disease underscores the necessity to develop and implement new treatment strategies, such as peptide-targeted radionuclide therapy.

Endocrine incidentalomas

OBJECTIVES

Endocrine incidentalomas are very common in the practice of every physician, mostly primary care and family physicians. Incidentalomas are discovered in the thyroid, pituitary and adrenal glands during imaging studies performed for non-endocrine reasons. The aim of this review article is to familiarise health professionals with all three endocrine incidentalomas, and give some guidance on how to initiate the right endocrine workup.

METHODS

We reviewed the most pertinent literature published on this topic through PubMed and Medline. We also discussed our own approach to incidentalomas in the endocrine clinic at Thomas Jefferson Hospital in Philadelphia.

RESULTS/CONCLUSIONS

Thyroid incidentalomas are very common, with a prevalence close to 50% on imaging studies. Thyroid-stimulating hormone (TSH) is the first test to obtain; if not suppressed, next step is fine-needle aspiration biopsy of any nodule above 1 cm and/or with suspicious ultrasound characteristics. Adrenal incidentalomas have a prevalence of almost 5%. All adrenal nodules above 4 cm should be resected. Regardless of the size, a workup for pheochromocytoma should always be done. Only hypertensive patients should be screened for primary hyperaldosteronism. Pituitary incidentalomas are also common, with a prevalence of 10-20%. All patients with pituitary masses should have a workup for hormonal hypersecretion. Only patients with macroadenomas will have additional screening for hypopituitarism and visual field defects. All hyperfunctioning adenomas are resected except prolactinomas which are treated medically. Similarly, if a macroadenoma is causing hypopituitarism or visual deficit, surgery should also be considered.

A prospective clinical trial to assess the efficacy of radioiodine ablation as an alternative to completion thyroidectomy in patients with differentiated thyroid cancer undergoing sub-total thyroidectomy

We conducted a prospective clinical trial to evaluate whether radioiodine ablation can be an effective alternative to completion thyroidectomy in patients undergoing sub-total thyroidectomy and if yes, the optimum activity of 131I and frequency of ablation. A total of 85 patients (F--63; M--22) with mean age of 37.9+/-12.3 years were recruited in this study. The pre-ablation mean 24 hour radioiodine neck uptake, effective half-life, residual thyroid tissue weight and TSH values were 13.9+/-8.5%, 4.5+/-0.9 days, 9.6+/-3.6 g and 11.7+/-6.4 microIU/ml, respectively. Thyroid tissue was completely ablated in 50 patients (58.8%, 95% CI:50-68%) after mean 1st administered activity of 32.3+/-10.7 mCi of 131I and the cumulative ablation rate was 91.8% after two doses of 131I. During mean follow-up duration of 49 months no local/distant recurrence has been observed so far in this cohort. It appears that radioiodine ablation may be an attractive alternative to completion thyroidectomy and an activity as low as 35 mCi may achieve reasonable ablation.

Sialoendoscopic treatment for radioiodine induced sialadenitis

BACKGROUND AND OBJECTIVE

The use of radioiodine (RI) for the ablation of residual thyroid tissue and metastatic thyroid cancer lesions after thyroidectomy has become established as standard treatment in the management of differentiated thyroid cancer and subsequent sialadenitis is the most common complication of RI therapy. The purpose of this study was to establish a new treatment modality for RI-induced sialadenitis.

METHOD

The study group consisted of 115 patients with a mean age of 47.7 (range, 24-78) years. All patients received RI therapy after total thyroidectomy. The incidence of RI-induced sialadenitis, salivary gland involvement, administered RI dose, treatment modality, and result of treatment by interventional sialoendoscopy were evaluated.

RESULTS

The incidence of RI-induced sialadenitis was 18% (21/115), with involvement of the parotid more frequent than the submandibular gland. The average development period of RI-induced sialadenitis was 4.8 months. The average RI dosage for the sialadenitis group was higher than for the nonsialadenitis group, suggesting that RI-induced sialadenitis may be dose related, although the data were not statistically significant because of the small numbers in the high-dose group. Conservative management was effective in 71% (15/21) of the cases, and interventional sialoendoscopy was successful in 50% of those cases that did not respond to conservative treatment. The causes of treatment failure in the remaining cases were a totally obstructed parotid duct and stenosis at the bifurcation site.

CONCLUSION

Sialadenitis is the most common complication after RI therapy. Sialadenitis was successfully managed by conservative treatment in most cases, and interventional sialoendoscopy is an alternative method of treatment in selected cases such as in partial ductal stenosis.

Predictive Value of the Preablation Serum Thyroglobulin Level After Thyroidectomy Is Combined With Postablation 131I Whole Body Scintigraphy for Successful Ablation in Patients With Differentiated Thyroid Carcinoma

OBJECTIVES

To investigate the clinical importance of the combined use of serum thyroglobulin (Tg) levels measured just before ablation (ablation-Tg) and postablation 131I whole body scintigraphy (WBS) patterns for predicting ablation success in patients with differentiated thyroid carcinoma who received total thyroidectomy and 131I ablation therapy.

METHODS

We retrospectively studied the early clinical outcomes for 81 differentiated thyroid carcinoma patients treated with total thyroidectomy and high-dose 131I ablation therapy between June 2001 and July 2004.

RESULTS

Ablation success was achieved in 42 (97.7%) of the 43 patients with uptake in the thyroid bed only and ablation-Tg levels less than 10 ng/mL, whereas successful ablation was achieved in 9 (75.0%) of the 12 patients with uptake in the thyroid bed only and ablation-Tg levels equal to or greater than 10 ng/mL (P = 0.029). Among 15 patients with uptake including a lymph node and ablation-Tg levels less than 10 ng/mL, 14 patients (93.3%) showed ablation success, whereas successful ablation was achieved in only 2 (18.2%) of the 11 patients with uptake including a lymph node and ablation-Tg levels equal to or greater than 10 ng/mL (P < 0.001).

CONCLUSIONS

These data indicate that the combined use of serum Tg levels measured just before ablation and the 131I WBS patterns after ablation may be an early predictor of ablation success in patients with differentiated thyroid carcinoma who received total thyroidectomy and high-dose 131I ablation therapy.

False-positive xerostomia following radioactive iodine treatment: case report

Radioactive iodine (131I), used in the treatment of differentiated thyroid carcinoma, is known to cause both short-term and long-term radiation damage to the salivary glands. The injury appears as glandular swellings and/or decreased salivation with 131I dosage and passage of time playing significant roles. A case report is presented to alert the profession to the existence of patients who have received 131I therapy and who complain shortly thereafter of xerostomia, but following a thorough examination are found to represent a group of false-positives. Emphasis is placed on the diagnostic techniques used in the differential diagnosis.

Defective efficacy of retinoic acid treatment in patients with metastatic thyroid carcinoma

Radioiodine (I-131) therapy is of proven efficacy for differentiated thyroid carcinoma. However, its efficacy relies on specific uptake mechanisms, which may be lost during the evolution of the disease. Attempts to increase the iodine uptake of such tumors have been made using retinoic acid because it exerts redifferentiating effects on thyrocytes. This study aims to assess the capability of the retinoic acid (RA) treatment to reinforce iodine 131-irradiation efficacy for metastatic and progressive multi-irradiated thyroid cancer. In this clinical prospective study, 11 patients (mean age +/- 1 SD = 61 +/- 12 years, sex ratio M/F = 5/6) with a progressive disease despite iterative surgery and iodine irradiations were treated with 13-cis-retinoic acid (1.5 mg/kg day) over 8 weeks prior to I-131 irradiation. The redifferentiating effect of RA was evaluated by serum thyroglobulin (Tg) monitoring during RA treatment and qualitative analysis of iodine uptake on the post-therapeutic whole body scan. The clinical usefulness of RA treatment was assessed by clinical follow-up, Tg monitoring, and tumor size. No serious event that could possibly be related to the treatment was reported. The mean follow up time was 24.2 +/- 12 months (range 3-46 months). Iodine uptake was only slightly improved in two patients. Nevertheless, the clinical benefits of RA seem to be very poor. Five patients died of a metastatic disease. Five others presented new clinical evidences of a progressive disease. In conclusion, this prospective study demonstrates the absence of efficacy of I-131 irradiation combined with RA for the treatment of patients with aggressive, rapidly growing metastatic thyroid cancer. Thus, patients with highly aggressive disease, rapidly growing in a short period from 2 to 6 months, should not be considered for RA therapy.

Sialadenitis following radioiodine therapy – a new diagnostic and treatment modality

OBJECTIVES

To explore the usage of salivary gland endoscope technique as a diagnostic tool as well as a novel treatment modality for sialadenitis following radioiodine therapy.

SUBJECTS AND METHODS

Fifteen patients suffering from sialadenitis of the major salivary glands after I131 therapy for thyroid carcinoma underwent a single procedure of sialoendoscopy under local anesthesia.

RESULTS

All the patients were free of sialadenitis after one sialoendoscopy procedure with no complications accompanied.

CONCLUSIONS

Sialoendoscopy is an efficient technique with low morbidity as well as a relatively simple surgical method for diagnosing and treating sialadenitis induced by radioiodine therapy for thyroid cancer patients.

Tumor-targeting properties of 90Y- and 177Lu-labeled alpha-melanocyte stimulating hormone peptide analogues in a murine melanoma model

The purpose of this study was to compare the tumor-targeting properties of (90)Y-DOTA-Re(Arg(11))CCMSH and (177)Lu-DOTA-Re(Arg(11))CCMSH in a murine melanoma mouse model.

METHODS

The in vitro properties of cellular internalization and retention of (90)Y-DOTA-Re(Arg(11))CCMSH and (177)Lu-DOTA-Re(Arg(11))CCMSH were studied in B16/F1 murine melanoma cells. The pharmacokinetics of (90)Y-DOTA-Re(Arg(11))CCMSH and (177)Lu-DOTA-Re(Arg(11))CCMSH were determined in B16/F1 melanoma-bearing C57 mice.

RESULTS

(90)Y-DOTA-Re(Arg(11))CCMSH and (177)Lu-DOTA-Re(Arg(11))CCMSH exhibited fast cellular internalization and extended cellular retention in B16/F1 cells. High receptor-mediated tumor uptake and retention coupled with fast whole-body clearance of (90)Y-DOTA-Re(Arg(11))CCMSH and (177)Lu-DOTA-Re(Arg(11))CCMSH were demonstrated in B16/F1 tumor-bearing C57 mice. The tumor uptakes of (90)Y-DOTA-Re(Arg(11))CCMSH and (177)Lu-DOTA-Re(Arg(11))CCMSH were 25.70 +/- 4.64 and 14.48 +/- 0.85 %ID/g at 2 h, and 14.09 +/- 2.73 and 17.68 +/- 3.32 %ID/g at 4 h postinjection. There was little activity accumulated in normal organs except for kidney.

CONCLUSIONS

High tumor-targeting properties of (90)Y-DOTA-Re(Arg(11))CCMSH and (177)Lu-DOTA-Re(Arg(11))CCMSH highlighted their potential as radiopharmaceuticals for targeted radionuclide therapy of melanoma in further investigations.

Role of131I in the treatment of well differentiated thyroid cancer

(131)I is an integral component in postsurgical management of well-differentiated thyroid cancer (WDTC), which includes papillary and follicular types. (131)I is used postsurgically to either destroy remaining thyroid tissue (thyroid ablation) or to treat recurrence and metastases (radioiodine therapy). (131)I is no longer a routine diagnostic modality, but it is widely used for remnant ablation after thyroidectomy for WDTC > 1 cm, under conditions of thyroxine withdrawal. It is generally-though not unanimously-accepted that postsurgical radioiodine is the most powerful method by which to lengthen disease-free survival. (131)I cannot be used if the residual thyroid remnant is large; many surgeons therefore perform near-total or total thyroidectomy for all WDTC > 1 cm. Since 1997, radioiodine treatment has been performed in outpatient settings, where side effects are common, but mild and transient. Secondary screening is by physical exam, thyroglobulin measurements, and (131)I diagnostic whole-body scans. This is performed under conditions of thyrotropin stimulation, which is accomplished either by thyroxine withdrawal or administration of recombinant human thyrotropin. While most cancers are well treated with radioiodine, some advanced cancers may no longer take up radioiodine, rendering them resistant to treatment. For these cancers, redifferentiation therapy and molecular target-specific medicines hold future promise for improved treatment.

Rediferenciación tumoral en carcinoma papilar de tiroides tras la administración de ácido retinoico

Male patient, 73 year old, with papillary thyroid carcinoma treated by surgery, 131I and L-Tyroxine, with bone metastasis, detected by bone scintigraphy and CT scan, which negative radioiodine uptake. In order to induce tumoral redifferentiation, retinoic acid (70 mg/day) was administered for three months before 131I treatment. A radioiodine scan performed after treatment showed uptake in some of the bone metastasis. Nine months later, and due to disease progression, a second induction with retinoic acid was performed before 131I treatment. The radioiodine scan performed after treatment showed greater uptake and higher number of bone lesions than the previous scan.

Comparing dual phase Tl-201 thyroid scan and fine-needle aspiration cytology to detect follicular carcinoma

It remains difficult to pre-operatively differentiate follicular carcinoma and adenoma even under intraoperative investigations including histopathologic diagnosis of frozen sections.

METHODS

We retrospectively compared dual phase thallium (Tl-201) thyroid scan and fine-needle aspiration (FNA) cytology to detect follicular carcinoma in 12 patients with cold thyroid nodules. Fine-needle aspiration cytology results were assessed and categorized by experienced pathologists into benign, suspicious, and malignant. Dual phase Tl-201 thyroid scan including an early (10-min) image and a delayed (3-hour) image were acquired after 2 mCi (74 MBq) of Tl-201 was injected intravenously. Dual phase Tl-201 thyroid scan findings were visually interpreted as positive and negative results.

RESULTS

Based on FNA cytologic interpretation criteria, three nodules were diagnosed as benign, five nodules were diagnosed as suspicious, and four nodules were diagnosed as malignant. However, based on dual phase Tl-201 thyroid scan interpretation criteria, all of the 12 nodules could accurately diagnose as malignant.

CONCLUSIONS

We conclude that dual phase Tl-201 thyroid scan was more accurate in diagnosing follicular carcinoma when comparing with FNA cytology.

Synthesis of dendrimer-based biotin radiopharmaceuticals to enhance whole-body clearance

To synthesize a biotin radiopharmaceutical that clears rapidly, dendrimer was used as a carrier and conjugated with succinimidyl 3-[(125)I]iodobenzoate and tetrafluorophenyl norbiotinamidosuccinate. Then, succinic anhydride was used to reduce its pI. In mice, the non-succinylated product showed high liver (67% ID/g) and kidney (44% ID/g) uptakes and whole-body retention (94% ID) at 20 min that persisted for 12 hr. The corresponding organ uptakes (22% and 11% ID/g) and the whole-body retention (47% ID) were drastically reduced by succinylation (p<0.0001). Lysine co-injection further lowered renal uptake.

Quantification of absorbed doses to urine bladder depending on drinking water during radioiodine therapy to thyroid cancer patients: a clinical study using MIRDOSE3

The object of the study was to quantify the absorbed doses to urinary bladder using MIRDOSE3 (medical internal radiation dose package program) depending on drinking water after giving radioiodine dose to thyroid cancer patients. Twenty-nine female thyroid cancer patients (aged 40-60 years, mean 50 years) were selected. The therapeutic doses ranged from 3700 to 7400 MBq of 131I. The radioiodine uptake was measured at 1 cm distance from three organs (previously marked), the thyroid, thigh and stomach, by using a calibrated Eberline ESP-2 GM counter, with a special arrangement of each patient. Urine samples were collected every 12 h for first 72 h, and then every 24 h for the next 96 h. The individual biological half-life of excreted urine was calculated using individual effective half-life. Absorbed doses were calculated for an adult female phantom using the dynamic bladder model of MIRDOSE3 program in two phases: firstly, for different voiding intervals; and secondly, depending on individual drinking water. An average of 85% of the total dose passed through the urinary tract within the first 72 h, with a biological half-life of 28.5+/-0.747 h, and 9% for the next 96 h with a biological half life of 118.43+/-0.645 h. The voiding interval shows great impact on total absorbed dose to bladder and water supplementation needs to be intensified to reduce absorbed doses to bladder wall for the first 3 days.

Radioactive iodine and the salivary glands

Radioactive iodine ((131)I) targets the thyroid gland and has been proven to play an effective role in the treatment of differentiated papillary and follicular cancers. Simultaneously, this radioisotope hones in on the salivary glands where it is concentrated and secreted into the saliva. Dose related damage to the salivary parenchyma results from the (131)I irradiation. Salivary gland swelling and pain, usually involving the parotid, can be seen. The symptoms may develop immediately after a therapeutic dose of (131)I and/or months later and progress in intensity with time. In conjunction with the radiation sialadenitis, secondary complications reported include xerostomia, taste alterations, infection, increases in caries, facial nerve involvement, stomatitis, candidiasis, and neoplasia. Prevention of the (131)I sialadenitis may involve the use of sialogogic agents to hasten the transit time of the radioactive iodine through the salivary glands. However, studies are not available to delineate the efficacy of this approach. Recently, amifostine has been advocated to prevent the effects of irradiation. Treatment of the varied complications that may develop encompass numerous approaches and include gland massage, sialogogic agents, duct probing, antibiotics, mouthwashes, good oral hygiene, and adequate hydration.

Scintigraphic evaluation of salivary gland dysfunction in patients with thyroid cancer after radioiodine treatment

PURPOSE

Sialadenitis is a well-recognized adverse effect of high-dose radioactive iodine treatment. This study was undertaken to determine whether Tc-99m pertechnetate salivary gland scintigraphy may be used for objective assessment of salivary gland function in patients with thyroid cancer treated with I-131.

PATIENTS AND METHODS

The study group consisted of 71 patients (16 men, 55 women) with a mean age of 44 years (range, 16 to 73 years). Twenty-six (37%) patients were not given any radioiodine, and 18, 16, and 11 patients received doses of 100, 150, or 200 mCi (or higher), respectively. Parotid and submandibular glands were evaluated based on a four-grade scoring system. Correlation between the type of surgery, administered dose, time since therapy, subjective symptoms, and findings of salivary gland scintigraphy were evaluated.

RESULTS

Subjective symptoms were questioned in 39 of the 45 patients who received radioactive iodine treatment. Fifty-four percent (21 of 39) of the patients reported xerostomia, of whom 86% (18 of 21) showed salivary gland dysfunction. Objective salivary gland dysfunction was observed in 69% (31 of 45) of patients. In 81% of the patients, the parotid glands were affected; in 13% of the patients, the submandibular glands were affected; and in 6%, both were affected ( < 0.000001). The frequency of salivary gland dysfunction showed a dose dependence to cumulative activity ( = 0.007). A greater complication rate was observed in patients with total thyroidectomy compared with subtotal surgery, although the correlation was not significant ( = 0.625).

CONCLUSIONS

Parenchymal damage to the salivary glands induced by radioactive iodine treatment can be evaluated by salivary gland scintigraphy. The impairment is worse in the parotid glands and increases with the total dose.

In vivo evaluation of 188Re-labeled alpha-melanocyte stimulating hormone peptide analogs for melanoma therapy

The purpose of our study was to optimize melanoma tumor uptake of 188Re-CCMSH and reduce its nonspecific kidney retention. Nephrotoxicity is often a serious problem associated with targeted radiotherapy, therefore, increasing the tumor/kidney uptake ratio of 188Re-CCMSH is crucial for optimizing its therapeutic efficacy. Structural modification of the peptide and amino acid co-infusion were investigated as strategies to improve the tumor/kidney uptake ratio of 188Re-CCMSH. The substitution of Lys11 with Arg11 was examined to determine if removal of lysine from the peptide would improve kidney clearance without sacrificing tumor uptake. The pharmacokinetics of 188Re-CCMSH and 188Re-(Arg(11))CCMSH were determined in B16/F1 murine melanoma-bearing C57 mice. Tumor uptake values of (188)Re-CCMSH and 188Re-(Arg(11))CCMSH were 15.03 +/- 5.20% ID/g and 20.44 +/- 1.91% ID/g at 1 hr postinjection and 1.94 +/- 0.47% ID/g and 3.50 +/- 2.32% ID/g at 24 hr postinjection. Renal retention of 188Re-(Arg(11))CCMSH was 11.79 +/- 1.29 ID/g and 3.67 +/- 0.51 ID/g at 1 hr and 4 hr postinjection, which was a greater than 50% reduction compared to 188Re-CCMSH. The Arg for Lys substitution in 188Re-(Arg(11))CCMSH resulted in improved tumor uptake and reduced kidney retention. Renal retention of both 188Re-CCMSH and 188Re-(Arg(11))CCMSH were significantly reduced by co-injection of 20 mg of L-lysine, L-arginine and a combination of L-lysine:L-arginine. Tumor/kidney uptake values for 188Re-CCMSH and 188Re-(Arg(11))CCMSH were maximally reduced by 52.9% and 46.3%, respectively. However, even with amino acid co-injection, the tumor/kidney ratio of 188Re-CCMSH was lower than that of 188Re-(Arg(11))CCMSH. Improved tumor uptake and reduced kidney retention of 188Re-(Arg(11))CCMSH will facilitate targeted irradiation of melanoma tumors while minimizing the dose to the kidneys.

The usefulness of serum thyroglobulin levels and Tl-201 scintigraphy in differentiating between benign and malignant thyroid follicular lesions

OBJECTIVE

To compare the diagnostic capabilities of various serum thyroglobulin levels (Tg) and Tl-201 scintigraphy with regard to thyroid follicular lesions.

METHODS

We examined 80 thyroid follicular lesions (benign: 55, malignant: 25) in patients with nodular goiter for whom a pathological diagnosis was made based on surgical findings. Tg was measured by an I-125 (radioimmunoassay) method. In Tl-201 scintigraphy, 74 MBq of Tl-201 chloride was intravenously injected and imaged after 10 minutes (early image) and after 120 minutes (delayed image), and the scintigrams were evaluated both visually and quantitatively, with special attention paid to the part of the nodule with the highest accumulation of Tl-201 chloride. The cutoff levels of Tg for categorizing the lesions as malignant were set at 40, 100, 300, 500, 1,000 and 2,500 microg/l. In Tl-201 scintigraphy, method I involved high uptake on both early and delayed images, method 2 involved high uptake on only the early image, and method 3 involved high uptake on only the early image or the same accumulation in comparison with the normal region on the early image, with no washout being quantitatively judged as indicative of malignancy. A summary index of overall test performance can be calculated as the area under the receiver operating characteristic (ROC) curve (Area (Az)). Likelihood ratios for several cutoff levels were also calculated.

RESULTS

In the diagnosis, Az of Tl-201 (0.95),was larger than that of Tg (0.65). The sensitivity and accuracy of Tg at each cutoff level (sensitivity: 4.0% to 76.0%, accuracy: 50.0% to 72.5%) were lower than with Tl-201 scintigraphy (methods 1-3, sensitivity: 76.0-100%, accuracy: 77.5-88.8%). The likelihood ratio for the positive results of method 1for Tl-201 scintigraphy, were greatest in the present study (13.9), and the likelihood ratio for the negative results of method 3 for Tl-201 scintigraphy, (0) was smallest in the present study.

CONCLUSION

Diagnosis based on Tl-201 washout patterns in which quantitative evaluation is combined with visual evaluation appears to be more useful for the differentiation of malignant thyroid follicular lesions than diagnosis by Tg.

Dosimetrically determined doses of radioiodine for the treatment of metastatic thyroid carcinoma

In the absence of definitive studies relating radioiodine dose to outcomes, selection of a dose of radioiodine to treat metastatic thyroid carcinoma is problematic, and several approaches have been used. These include empiric fixed doses and doses used on dosimetric approaches specific for each patient. This paper is a review of the rationale and technique for dosimetrically-determined doses of radioiodine for the treatment of metastatic thyroid carcinoma. This review (1) discusses the alternatives for selection of a dose, (2) discusses the two major approaches for determining radioiodine doses dosimetrically, (3) briefly reviews several modifications of these approaches, (4) reviews the literature regarding the results, (5) discusses the side effects of these different approaches, and (6) concludes with recommendations for patient management and future research. This review does not address use of dosimetrically-determined doses of radioiodine for the initial ablation of thyroid tissue postoperatively.

Tracheal invasion by thyroid carcinoma: prediction using MR imaging

OBJECTIVE

The purpose of this study was to evaluate the accuracy of MR imaging in predicting tracheal invasion by thyroid carcinomas and to determine MR imaging criteria for diagnosing tracheal invasion.

MATERIALS AND METHODS

MR imaging was performed on the normal trachea of one cadaver and 30 healthy subjects as a standard of reference. Then, MR imaging findings in 67 patients with thyroid carcinoma were reviewed and correlated with surgical and pathologic findings. A logistic regression model was used to determine which MR imaging features were significant for predicting tracheal invasion.

RESULTS

Twenty-three (34%) of the 67 patients had tracheal invasion. Logistic regression model analysis revealed that significant MR characteristics for determining tracheal invasion included soft-tissue signal in the tracheal cartilage (p < 0.001), intraluminal mass (p < 0.001), and degree of tumor circumference around the trachea (p = 0.001). The highest accuracy (90%) for determining tracheal invasion was achieved using a combination of findings. A case was considered positive for tracheal invasion if there was soft-tissue signal in the cartilage, an intraluminal mass, or a tumor that abutted a circumference of the trachea of 180 degrees or greater. Using these factors resulted in seven false-positive diagnoses because soft-tissue signal in the cartilage was sometimes seen in healthy trachea. Although intraluminal mass invariably reflected deep tracheal invasion, soft-tissue signal in the cartilage rarely indicated actual cartilage invasion but rather indicated tumor extension between the cartilaginous rings.

CONCLUSION

Tracheal invasion by thyroid carcinomas can be accurately diagnosed with MR imaging, and using a combination of criteria is the most accurate method of predicting this phenomenon.

Post-surgical ablation of thyroid remnants with high-dose (131)I in patients with differentiated thyroid carcinoma

The aims of this study were to evaluate the efficacy of an empirically determined "fixed" high ablative dose of radioiodine ((131)I) therapy and to determine the utility of ultrasonography (US) in dose determination. A retrospective analysis was performed of 242 thyroid cancer cases treated with "fixed" high-dose (131)I for ablation of thyroid remnants without a pre-ablative (131)I diagnostic scintigraphy or radioiodine uptake study. Treatment doses ranged from 1850 MBq (50 mCi) to 7.4 GBq (200 mCi). The selection of the treatment dose was based on the surgical and pathological findings as well as the remnant thyroid volume calculated by US. A successful ablation was defined as the absence of activity in the thyroid bed on subsequent imaging studies. Successful ablation was obtained in 218 of the 242 patients (90%). In 162 of the 218 patients (74.3%), successful ablation was achieved after a single (131)I treatment. The remnant thyroid volume calculated by US was significantly different (P=0.04) between those who were successfully ablated and those who were not. The total (131)I dose needed for successful ablation was significantly higher in males (P=0.003). Patients with higher post-operative thyroglobulin (Tgb) levels and patients with a higher stage of disease required higher doses (P=0.036 and P=0.021 respectively). Serum Tgb levels were under 10 ng.ml(-1) in 220 of the 242 patients (90%) following radioiodine ablation while not receiving L-thyroxine suppression. Nineteen patients (7.8%) showed metastases on post-therapy scan and successful treatment was achieved in 11 of 19 (57.8%). Four of the 19 patients with distant metastases (revealed on post-treatment scan) were found to have been given a treatment dose of less than 200 mCi based on the proposed empirical approach. These results indicate that "fixed" high-dose (131)I treatment is clinically feasible with an acceptable dose underestimation rate, and the utilization of US in the determination of the thyroid remnant volume provides more accurate and reproducible results.

Artifacts, anatomical and physiological variants, and unrelated diseases that might cause false-positive whole-body 131-I scans in patients with thyroid cancer

The whole body 131-I scan remains an important component in the postoperative treatment of patients with well-differentiated thyroid cancer. Because normal thyroid tissue remnants and residual or metastatic foci of well-differentiated thyroid cancer have the unique ability to concentrate, organify, and store 131-I, the whole body scan provides a depiction of those tissues that can be ablated with therapeutic doses of 131-I. Over time, it has become obvious that the whole body scan may also reveal foci of 131-i uptake owing to a wide variety of other causes. We provide a detailed pathophysiological classification of the artifacts, anatomic and physiological variants, and nonthyroidal diseases that may give rise to false-positive whole body scans in postoperative patients with thyroid cancer. These include ectopic foci of normal thyroid tissue; nonthyroidal physiological sites (eg, choroid plexus, salivary glands, gastric mucosa, urinary tract); contamination by physiological sections; ectopic gastric mucosa; other gastrointestinal abnormalities; urinary tract abnormalities; mammary abnormalities; serous cavities and cysts; inflammation and infection; nonthyroidal neoplasms; and currently unexplained causes. This article also provides a detailed review of the widely scattered English language literature in which these phenomena were originally described.

Dietas com restrição de Iodo (DRI)

No contexto do manuseio do câncer diferenciado de tireóide com 131I, faz-se histórico e descrição das dietas com restrição de iodo (DRI). Elabora-se DRI mais abrangente e auto-explícita. Expõem-se mecanismos de aumento de captação pelas DRI, baseados na expoliação de iodo. Comprova-se a eficacia das DRI em favorecer expoliação e rastreamento; o possível benefício quanto a dose ablativa; não ter-se demonstrado efeito em dose terapêutica, quiçá por insuficiente pesquisa; a importância de obter iodúria inferior a 50ug/dia ou 50ug/g creatinina, para prevenir contaminação e avaliar a eficácia e adesão a DRI. Diante da excessiva ingestão de iodo nos EUA, Reino Unido e países asiáticos, com resultante queda na atividade iodocaptante, deplora-se a escassa adoção de DRI, em relatos de centros de pesquisa, cuja credibilidade só é sustentável, admitindo-se tácita prescrição de DRI informal, raramente constando em "Materiais e Métodos". Outrossim, condena-se o aumento de dose de 131I, na contaminação: a rápida expoliação de iodo por DRI é eficiente e inócua. Comenta-se a inexistência de DRI publicada no Brasil, duvidando-se de sua necessidade, face à deficiência endêmica de iodo, em algumas regiões. O desconhecimento de seu conteúdo, e de eventual excesso, em alguns alimentos, conduz o autor a elaborar algoritmo: 1. Avaliação de quota de iodo alimentar das populações, ou 2. Exclusão de contaminação, pela medida da iodúria, ou 3. Prescrição de DRI. O autor propõe o axioma: "A DRI pode às vezes não ser benéfica, a contaminação é sempre maléfica".

Benign oral disease as a cause of false-positive iodine-131 scans

Post-thyroidectomy I-131 whole-body scintigraphy is an important aspect in the management of patients with thyroid cancer. The scan is used to detect residual thyroid tissue and distant functioning metastases. Extrathyroid I-131 accumulation does not always denote metastatic disease, and several potential sources of false-positive I-131 scans have been identified. This report presents four cases of benign oral disease as a cause of false-positive I-131 uptake. Benign oral disease has not been documented previously as an important source of false-positive I-131 whole-body scans.

Unusual false-positive radioiodine whole-body scans in patients with differentiated thyroid carcinoma

Radioiodine whole-body imaging is the most accurate method in the diagnosis of metastases from differentiated thyroid cancer. However, false-positive images rarely occur. The authors report unusual cases of thymic hyperplasia and post-traumatic skull changes mimicking mediastinal, skull, or cerebral metastases. Nonthyroidal causes were diagnosed by other radionuclide studies (bone and brain scintigraphy) and CT scans. Follow-up and undetectable thyroglobulin levels helped confirm the benign cause.

Dosimetric considerations in the radioiodine treatment of macrometastases and micrometastases from differentiated thyroid cancer

When macrometastases are delineated clearly using current radiographic techniques and/or physical examination and can be shown to concentrate 131I, the therapeutic activity to be administered may be determined quantitatively. Administrations of 131I that will deliver 30,000 rad to residual thyroid tissue or 10,000 +/- 2,000 rad to lymph node metastases will ablate them successfully 80% of the time, and bone marrow depression that is severe enough to require specialized treatment will be avoided if the whole blood dose from a single administration does not exceed 200 rad. When micrometastases are detected only by diagnostic radioiodine imaging and/or elevations of serum thyroglobulin levels, and when a clinical decision is made to treat them with radioiodine, then 131I may not be the isotope choice. With small lesions < 0.05 mm in diameter, the lower energy emissions of 125I therapy may be more suitable. With the advent of alternative methods of patient preparation for radioiodine therapy, empiric approaches that were derived from experience with endogenously hypothyroid patients will require full re-evaluation. Approaches based on quantitative radiodosimetric calculations will continue to be valid because they already consider individual differences in radioiodine kinetics.

False-positive radioiodine uptake in the abdomen and the pelvis: radioiodine retention in the kidneys and review of the literature

Because the kidneys are usually not visualized on radioiodine whole-body scans, the renal uptake can be mistaken for a thyroid cancer metastasis. The authors report the prevalence and characteristics of radioiodine retention in the kidneys and review the reported causes of false-positive radioiodine uptake in the abdomen and pelvic areas. Radioiodine uptake in the renal bed was noted on 9 of 400 (2.2%) I-123 diagnostic whole-body scans performed over a 7-month period in our center. The uptake was noted more clearly on posterior views, cleared on delayed images after further hydration, and was not consistently present on follow-up scans. It was unilateral and mimicked a renal or adrenal metastasis in 44% of the scans. In three cases, the uptake was associated with a dilated calyx, an extrarenal pelvis, or a voluminous pelvis. False-positive radioiodine uptake in the abdomen and pelvis has been previously reported in association with 14 different conditions. However, renal retention may represent the most common cause of false-positive radioiodine uptake in the abdomen pelvis. Delayed imaging after additional hydration is usually sufficient to clarify its origin.

Short-term hazards of low-dose radioiodine ablation therapy in postsurgical thyroid cancer patients

During the last two decades, there has been a trend to use low-dose I-131 ablation therapy in patients with thyroid carcinoma without metastases. However, information regarding the incidence of acute adverse reactions in patients after low-dose radioiodine therapy has not been reported. In this study, the acute radiation effects after low-dose radioiodine ablation therapy in postsurgical differentiated thyroid cancer patients was evaluated. Fifty-six patients with differentiated thyroid cancer were prospectively evaluated. None of these patients had evidence of a distant metastasis. All patients received 40 mCi (1480 MBq) I-131 MIBG orally and were evaluated for symptoms and signs by a physician on the second and seventh days after therapy. Xerostomia and nausea were the most common complaints with the same incidence rate of 5.35%. Gastralgia occurred at a frequency of 3.57%. Pain in the thyroid bed, tenderness over a parotid gland, submandibular glands, change in taste, and vomiting all were found at a frequency of 1.78%. Maximum reactions generally occurred 24-48 hours after therapy. All the symptoms except for xerostomia resolved completely in most patients within a week. In comparison with high-dose ablation therapy published in the literature, the incidence of radiation reactions in low-dose radioiodine therapy was much lower. It was concluded that in patients without lymph node or distant metastases, low-dose I-131 MIBG therapy may be recommended to avoid the high incidence of local complications after high-dose treatment.

Inflammatory diseases of the lung causing false-positive 131iodine whole body scans in the evaluation of papillary thyroid carcinoma. Two case reports

The 131I whole body scan is commonly used to establish the presence of metastatic disease in papillary thyroid carcinoma. False-positive scans are rare, but have been reported. We present two cases of aberrant uptake of radioiodine after thyroidectomy and 131I ablation due to inflammatory conditions of the lung, aspergilloma, and respiratory bronchiolitis.

Iodine-131 labelled octreotide: not an option for somatostatin receptor therapy

Gamma-emitting radiopeptides are useful for scintigraphy of tumours on the basis of receptor binding. Likewise, beta-emitting radiopeptides may be used in radionuclide therapy of such tumours. As iodine-131 suggested to be suitable for this purpose, experiments were performed using three somatostatin analogues, in which the effects of coupling of a therapeutic dose of 131I to such peptides were investigated. This study deals with the radioiodination of very small amounts of peptide on a therapeutic scale, the required purification procedures after radioiodination, and the influence of high beta fluxes from 131I on a peptide during radioiodination and purification. Based on the regularly used therapeutic doses of 131I in cancer treatment and our previous experience with [111In-DTPA-D-Phe1]-octreotide, it was assumed that a minimal effective therapeutic dose of 3.7 GBq 131I has to be coupled to a maximum of approximately 100 microg peptide, representing only a slight excess of peptide over 131I. This contrasts with non-peptide radiopharmaceuticals in which high compound to radionuclide ratios are usually used. Labelling at low peptide to radionuclide ratios (low labelling yields) results in the formation of di-iodinated compounds, whereas at high peptide to radionuclide ratios (high labelling yields) mono-iodinated products of low specific activity are formed. Thus, after radioiodination the desired mono-iodinated peptide has to be separated from unreacted iodide, and from di-iodinated and unreacted peptide, as both compounds compete for the receptors. Possible radiolysis of the peptide during labelling and separation steps were investigated by irradiating 30 microgram unlabelled peptide with 370 MBq 131I in a small volume. The peptide composition of the incubation mixtures was investigated by high-performance liquid chromatography after irradiation for 30 min to 24 h. The results showed that the peptide was degraded with a half-life of less than 1 h. During the preparation of a real therapeutic dose (at much higher beta-flux) the peptide will be degraded even faster during the various steps required. In conclusion, intact mono-iodinated 131I-labelled somatostatin analogues for peptide receptor therapy will be difficult to obtain.

An unusual adrenal metastasis secondary to Hürthle cell carcinoma of the thyroid

A 66-year-old woman with Hürthle cell thyroid carcinoma associated with a right adrenal gland metastasis suspected on a postradioiodine therapy scan, is reported. Histology specimens confirmed the suspicion. Adrenal metastases have never been reported previously in this kind of tumor. On radionuclide imaging, there was marked I-131 uptake in the tumor remnant and its metastases, and the tumor spread through both lymphatic and hematogenous routes, as shown by lymph node, bone, and lung metastases.