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The purpose of this prospective study was to determine the incremental diagnostic value of single photon emission computed tomography/computed tomography with iodine-131 over planar whole body scan in the staging of patients with differentiated thyroid carcinoma. A total of 365 patients (270 female, 95 male) with differentiated thyroid carcinoma were treated with radioiodine therapy for thyroid remnant ablation with radical intent after thyroidectomy between January 2013 and November 2014. In addition to planar whole body scan, single photon emission computed tomography/computed tomography of neck and chest were performed. Each radioactive focus at whole body scan was classified as positive or equivocal with respect of specific territories: thyroid bed, cervical lymph nodes and distant metastases.Whole-body scan detected focal uptake in 353 patients and no uptake in 12. The location was considered equivocal in 100. Single photon emission computed tomography/computed tomography detected focal uptake in 356 patients and no uptake in nine. In three patients with negative wholebody scan, single photon emission computed tomography/computed tomography provided information about residual activity in the thyroid bed. By single photon emission computed tomography/computed tomography the location was equivocal in 18 patients only. Single photon emission computed tomography/computed tomography was helpful in 82 out of 100 patients with equivocal findings by whole body scan allowing a correct identification of the uptake sites. In a great number of equivocal whole body scan, due to high remnant activity, single photon emission computed tomography/computed tomography was able to differentiate between thyroid remnant and lymph nodes uptake. In 22 out of 100 patients with doubtful whole body scan, single photon emission computed tomography/computed tomography correctly identified nodal or distant metastases, and in 2/100 patients, focal uptake classified as metastatic by whole body scan was reclassified as para-physiological by single photon emission computed tomography/computed tomography. The TNM classification changed in 13 out of 22 patients. Single photon emission computed tomography/computed tomography improves detection and localization of the iodine-131 uptake after thyroidectomy in patients with differentiated thyroid carcinoma and it is more accurate than whole body scan to evaluate lymph nodes and to identify and characterize distant metastases. Single photon emission computed tomography/computed tomography aids assessment of lower/upper stage in a significant number of patients with differentiated thyroid carcinoma and it can affect therapy decision-making and patient management. more...

A 68-year-old man underwent adjuvant radioiodine therapy for follicular variant papillary thyroid carcinoma. Post-therapeutic whole-body I scan showed abnormal radioiodine uptake on the right side of back. SPECT/CT localized this abnormal activity from a small subcutaneous lesion with fat density between the right 10th and 11th rib. Under ultrasound-guided autopsy, the lesion was confirmed as lipoma. more...

Context: Published studies of thyroid stunning due to preablation (131)I scanning in the treatment of differentiated thyroid cancer after thyroidectomy had shown inconsistent clinical impact., Objective: The objective of the study was to evaluate the clinical outcome in patients who were given a low diagnostic (131)I activity (1.1 mCi or 40 MBq) 6 days prior to radioiodine ablation (RAI)., Design/setting: Two cohorts of patients were treated in a cancer referral center in 2004-2011. The eligibility criteria were as follows: 1) diagnosis of differentiated thyroid cancer; 2) total or near total thyroidectomy; 3) no distant metastasis; and 4) receiving 82.4 mCi or greater (3050 MBq) therapeutic (131)I activity., Patients/interventions: Three hundred five consecutive patients treated in 2004-2008 (group A) had a diagnostic activity 1.1 mCi of (131)I prior to RAI. The second cohort treated in 2009-2011 (group B) consisted of 237 patients who did not undergo diagnostic (131)I scanning prior to RAI., Main Outcome Measures: The tumor recurrence rate at 3 years and quantitative assessment using diagnostic whole-body radioiodine scans and TSH-stimulated thyroglobulin levels at 3-12 months after RAI were measured., Results: The 3-year recurrence-free survival rates were 96.4% in both groups, with 4.3% in group A and 3.4% in group B having tumor recurrence (P = .91). The ablation success rates measured by diagnostic whole-body radioiodine scans were 97.6% and 100% and by stimulated thyroglobulin were 85.3% and 85.8% in group A and B, respectively (P = .62)., Conclusions: The use of low diagnostic (131)I activity (1.1 mCi) given 6 days prior to RAI was safe and convenient without adversely affecting the long-term clinical outcome. more...

Background: The most important side effect of radioiodine ((131)I) therapy is sialoadenitis and xerostomy., Aim: To evaluate by ultrasound (US) parotid and submandibular glands after (131)I therapy for differentiated thyroid cancer (DTC)., Patients: Seventy-six subjects thyroidectomized for DTC submitted to salivary glands US examination. Forty-three of them had been previously treated with (131)I: 22 with 1.11 GBq (30 mCi) for remnant ablation, and 21 with higher doses [up to 44.4 GBq (1200 mCi)] for metastases. Thirty-three subjects studied before (131)I therapy served as controls. Parotid and submandibular volume, homogeneity, and echogenicity were determined. (131)I-treated patients filled a questionnaire about sialoadenitis symptoms., Results: Parotid gland volume was significantly higher in treated patients (28.3±16.2 ml) than in untreated patients (20.7±10.4 ml, p=0.0154) and related to the time from last (131)I therapy. Three had parotid volume <1.5 ml and complained severe xerostomy. Submandibular gland volume was similar in treated (11.2±7.6 ml) and untreated patients (8.6±4.2 ml, p=0.0602). Homogeneity and echogenicity were similar in treated and untreated patients. Sialoadenitis symptoms were reported in 26% and were related to the (131)I cumulative dose. Symptoms were not related to gland volume. Hypoechogenicity and inhomogeneity of the parotids were more frequent in patients with salivary stickiness., Conclusion: Parotid, but not submandibular, volume is increased after (131)I treatment depending on the received activity and the time from irradiation but not on sialoadenitis symptoms. Xerostomy is associated to gland atrophy at US., (©2013, Editrice Kurtis) more...

Background: Distant metastases of differentiated thyroid cancers are exceptionally localized in the soft tissues and the pelvic cavity. This last event complicates diagnosis, especially in female patients because of false positive nuclear imaging and unrelated iodine uptakes. False positive due to body secretions, urinary and fecal iodine retention and iodine uptake by non-thyroid tissues or ectopic thyroid tissue and bone metastasis of differentiated thyroid carcinoma., Methods: We present two cases of metastasectomy, guided by a peroperative gamma probe and intraoperative frozen sections of the specimens. In females patients because of potentially false positive nuclear imaging and iodine uptakes unrelated to pathology, it is very difficult to identify a pelvic metastasis. Our experience of two cases underlines these pitfalls and the possibilities to avoid them: the use of 131 Iodine SPECT/CT whole body scan, peroperative gamma probe and intraoperative frozen sections of specimen., Conclusion: Preoperative localization needs a precise 3D imaging and the surgical treatment must be guided by a peroperative gamma probe and frozen sections., (Celsius.) more...

Differentiated thyroid cancer (DTC) is usually indolent with good prognosis and long-term survival. However, DTC distant metastasis is often a grave event and accounts for most of its disease-specific mortality. The major sites of distant metastases are the lung and bone. Metastases to the brain, breast, liver, kidney, muscle, and skin are rare or relatively rare. Nevertheless, recognizing rare metastases from DTC has a significant impact on the clinical decision making and prognosis of patients. (131)I single photon emission computed tomography/computed tomography ((131)I-SPECT/CT) can provide both metabolic and anatomic information about a lesion; therefore, it can better localize and define the (131)I-WBS findings in DTC patients. In this pictorial review, the imaging features of a range of rare metastases from DTC are demonstrated, with a particular emphasis on the (131)I-SPECT/CT diagnostic aspect. more...

(131)I is given in differentiated thyroid cancer (DTC) without taking into account thyroglobulin (Tg) levels at the time of ablation, whereas 6-18 months later it is a major criterion for cure. This single-center retrospective study assessed the frequency and risk factors for persistent disease on postablation whole body scan (WBS) and postoperative neck ultrasonography (n-US) and for recurrent disease during the subsequent follow-up, in patients with DTC and undetectable TSH-stimulated Tg level (TSH-Tg) in the absence of Tg antibodies (TgAb) at the time of ablation. Among 1031 patients ablated, 242 (23%) consecutive patients were included. Persistent disease occurred in eight cases (3%) (seven abnormal WBS and one abnormal n-US), all with initial neck lymph node metastases (N1). N1 was a major risk factor for persistent disease. Among 203 patients with normal WBS and a follow-up over 6 months, TSH-Tg 6-18 months after ablation was undetectable in the absence of TgAb in 173 patients, undetectable with TgAb in 1 patient and equal to 1.2  ng/ml in 1 patient. n-US was normal in 152 patients and falsely positive in 3 patients. After a mean follow-up of 4 years, recurrence occurred in two cases (1%), both with aggressive histological variants. The only risk factor for recurrence was an aggressive histological variant (P = 0.03). In conclusion, undetectable postoperative TSH-Tg in the absence of TgAb at the time of ablation is frequent. In these patients, repeating TSH-Tg 6-18 months after ablation is not useful. (131)I ablation could be avoided in the absence of N1 and aggressive histological variant. more...

Objective: The objective of this study was to determine whether the use of recombinant human TSH (rhTSH) to stimulate radioiodine uptake after thyroidectomy is as efficacious as a period of withholding thyroid hormones, while at the same time avoiding hypothyroidism, reducing sick leave time and shortening the hospital stay., Design: Our aim was to compare the standard procedure of differentiated thyroid cancer treatment, which consists of thyroidectomy followed by 4 weeks of hypothyroidism and a conclusive ablative activity of (131)iodine, with a new shortened treatment in which l-thyroxine (T(4)) medication is initiated a day after thyroidectomy, followed by application of rhTSH stimulation and subsequent ablation a few days after surgery. We presumed our treatment to represent the most sophisticated strategy for the reduction in sick leave days overall without any reduction in safety or the efficacy of ablative therapy., Methods: Patients (n=25) were randomized either for surgery and rhTSH stimulation or surgery and l-T(4) abstinence before the first application of radioiodine. Ablation success was determined by neck ultrasound and serum thyroglobulin during follow-up. RhTSH receivers were monitored for an average of 635 days (s.d.+/-289) and patients in l-T(4) abstinence for an average of 624 days (s.d.+/-205). Both groups were statistically compared for significant differences in treatment efficacy, safety and overall time of sick leave., Results and Conclusions: Our shortened treatment proved to be equally efficacious and safe in comparison with the conventional therapy regimen. At the same time, it showed economic advantages through the reduction in average sick leave time from approximately 29 days (l-T(4) abstinence) down to approximately 6 days (rhTSH stimulation) as well as sustaining the patient's quality of life by the complete avoidance of hypothyroidism. more...

Patients with poorly differentiated thyroid cancers (PDTC), anaplastic thyroid cancers (ATC), and radioactive iodine-refractory (RAIR) differentiated thyroid cancers have a high mortality, particularly if positive on [(18)F]fluorodeoxyglucose (FDG)-positron emission tomography (PET). To obtain comprehensive genetic information on advanced thyroid cancers, we designed an assay panel for mass spectrometry genotyping encompassing the most significant oncogenes in this disease: 111 mutations in RET, BRAF, NRAS, HRAS, KRAS, PIK3CA, AKT1, and other related genes were surveyed in 31 cell lines, 52 primary tumors (34 PDTC and 18 ATC), and 55 RAIR, FDG-PET-positive recurrences and metastases (nodal and distant) from 42 patients. RAS mutations were more prevalent than BRAF (44 versus 12%; P = 0.002) in primary PDTC, whereas BRAF was more common than RAS (39 versus 13%; P = 0.04) in PET-positive metastatic PDTC. BRAF mutations were highly prevalent in ATC (44%) and in metastatic tumors from RAIR PTC patients (95%). Among patients with multiple metastases, 9 of 10 showed between-sample concordance for BRAF or RAS mutations. By contrast, 5 of 6 patients were discordant for mutations of PIK3CA or AKT1. AKT1&#95;G49A was found in 9 specimens, exclusively in metastases. This is the first documentation of AKT1 mutation in thyroid cancer. Thus, RAIR, FDG-PET-positive metastases are enriched for BRAF mutations. If BRAF is mutated in the primary, it is likely that the metastases will harbor the defect. By contrast, absence of PIK3CA/AKT1 mutations in one specimen may not reflect the status at other sites because these mutations arise during progression, an important consideration for therapies directed at phosphoinositide 3-kinase effectors. more...

Background: Retinoic acid (RA) treatment has been used for redifferentiation of metastatic thyroid neoplasia that have lost radioiodine (131I) uptake with heterogeneous results., Aim: Retrospective analysis of the recovery rate of 131I uptake after RA treatment in patients from 11 Spanish hospitals., Methods: Twenty-seven patients (14 men, 13 women) with papillary [21], follicular [4], and oncocytic [2] thyroid cancer initially treated with total thyroidectomy plus 131I, and with 131I negative metastatic disease, were given 13-cis RA (0.66-1.5 mg/kg for 5-12 weeks) followed by a therapeutic 131I dose (3700-7400 MBq); 3 months later thyroglobulin levels and computed tomography imaging were performed., Results: In 9 out 27 cases (33%) (8 papillary, 1 follicular) optimal positive 131I scan was observed after RA treatment; in the remaining 18, 10 had a suboptimal uptake (7 papillary, 2 follicular, 1 oncocytic) and in the rest there was no 131I uptake recovery (6 papillary, 1 follicular, 1 oncocytic). In 17 positive responses to RA (either optimal or suboptimal) in which image follow-up was available, decrease or stabilization of metastatic growth was observed in 7, while tumor mass increased at short term in the remaining 10. No major side effects were detected., Conclusion: Quite a high rate of 131I uptake recovery after RA treatment may be obtained in advanced differentiated thyroid cancer, but the potential modification of the natural course of the disease is uncertain. A better biological characterization of these tumors allowing the identification of potential responders to RA may improve the outcome of RA coadjuvant therapy. more...

Unlabelled: Thyroglobulin (Tg) is a specific marker of residual thyroid cancer or tumor recurrence. In patients with elevated Tg levels and negative diagnostic radioiodine (131I) whole-body scans (dWBS), administration of a therapy dose may reveal foci that were not initially apparent. The aim of this study was to identify factors, other than 131I activity, which might explain why a post-therapy 131I whole-body scan is sometimes positive despite a negative dWBS., Patients and Methods: We reviewed data on all patients with elevated Tg levels and negative dWBS with 185 MBq 131I off-T4 at followup, who subsequently received an empiric therapy dose of 3700 MBq of 131I. During a 5-yr period, 22 patients met these criteria. 131I therapy could be given immediately after negative dWBS in 9 patients, with an average of 8 extra days of hypothyroidism. In the other 13 patients, therapy was given an average of 8 months later., Results: The therapy scan was negative in 16 patients, while it showed uptake in the thyroid bed in 5 patients and distant metastases in two. In the latter two patients, the TSH level was suboptimal at the time of dWBS (9 and 25 microIU/ml), and had risen to 34 and 70 microIU/ml respectively at the time of therapy. Overall, a positive scan following therapy occurred in 7 patients (6/9 patients treated immediately and 1/13 patients treated in a separate setting; p<0.01). In patients with positive therapy scans, the mean TSH level was 73 microIU/ml at the time of dWBS and 103.5 microIU/ml at the time of therapy (41% increase; p<0.05). In patients with negative therapy scans the mean TSH level was 84 microIU/ml at dWBS and 86 microIU/ml at the time of the therapy scan (2% increase)., Conclusions: Our study suggests that interval increase in TSH level with a longer period of stimulation may have contributed to making the whole-body scan positive at the time of therapy. Nowadays, patients with elevated Tg are directly given a therapy dose of 131I. Special care should be taken when preparing patients who have been on suppressive levothyroxine therapy for a long time, in order to avoid misclassifying the tumor as non-functioning. more...

Purpose: To determine if stunning can be seen with a 185-MBq (5-mCi) dose of iodine 131 (131I) at diagnostic whole-body scanning and, if stunning is seen, determine if there is any 131I therapeutic efficacy., Materials and Methods: A retrospective review of findings involving 166 patients who underwent thyroidectomy for differentiated thyroid carcinoma was performed. Diagnostic 131I scans were compared with postablation scans for evidence of stunning. Stunning was defined when the diagnostic scan showed activity that was subsequently decreased on the postablation scan. The sample population was divided into two groups: group NS, patients with no stunning, and group S, patients with stunning. Patients were considered successfully treated if no functioning thyroid tissue and/or metastases were seen on follow-up diagnostic scans. Fisher exact and Student t tests were used to evaluate the statistical significance of therapy success rates, clinical characteristics, and scanning parameters between the two groups., Results: Group NS included 135 (81.3%) of 166 patients, with 36 (26.7%) of 135 lost to follow-up. Group S included 31 (18.7%) of 166 patients, with eight (26%) of 31 patients lost to follow-up. There was no significant difference (P =.61) in treatment success rates between group NS (87 of 99, 88%) and group S (21 of 23, 91%). The treatment success rates for thyroid remnants were 87% (48 of 55) for group NS and 91% (10 of 11) for group S (P =.63). Treatment success rates for metastases (mostly lymph nodes) were 89% (39 of 44) for group NS and 83% (10 of 12) for group S (P =.55)., Conclusion: Thyroid stunning can occur with 185 MBq of 131I in diagnostic imaging. However, data did not show any effect of stunning on the efficacy of 131I therapy for differentiated thyroid carcinoma., (Copyright RSNA, 2004) more...

Twenty-six patients who had undergone recent surgery for differentiated thyroid cancer were investigated using iodine-131 iodide (120 MBq). Uptake in the thyroid bed was measured at 3 days using a dual-head gamma camera. An ablation activity of 131I iodide (4,000 MBq) was administered 3-38 (median 14) days later and uptake in the thyroid bed measured once or twice, 1-3 days post therapy. For measurements post therapy, the gamma camera was operated in the high-count rate mode with appropriate correction factors to compensate for any count loss. A further 16 patients were given iodine-123 iodide (200 MBq) as the diagnostic agent and uptake was measured at 24 h. The ablation activity was administered 5-47 (median 19) days later and uptake again measured at 24 h. In some cases, a further measurement of uptake was made within the period 1-3 days post therapy. Reduced uptake of the therapeutic administration ( P<0.001) was observed in all 26 patients given diagnostic 131I, with a median value of 32.8% (range 6%-93%) of the uptake in the diagnostic study. In the patients given diagnostic 123I, reduced uptake of the ablative radioiodine was observed in 15 of the 16 patients ( P<0.001), and overall the median value was 58.8% (range 17%-130%) of the diagnostic uptake. In one case the uptake post therapy was increased. The stunning observed in the group given 123I was significantly less ( P<0.001) than in the group given 131I. In the patients given diagnostic 131I, stunning appeared to increase in severity the longer the time interval between the diagnostic and therapeutic radionuclides, for intervals up to 25 days. Thereafter, there seemed to be some recovery of uptake capability. Overall there was no evidence of a large rapid loss of radionuclide from the thyroid bed 1-3 days post therapy. The stunning observed using 123I could not be explained by errors in the estimation of relative uptake due to different tissue absorption of the 131I and 123I photons, nor by the radiation dose delivered by the 123I. However, the ablative 131I itself may cause stunning because the cumulated activity, over the first few hours of uptake, is not insignificant when compared with all the cumulated activity from a diagnostic administration of 131I. The resultant radiation dose to the thyroid remnant, as the therapeutic radioiodine is being taken up, may be sufficient to inhibit the uptake process, thus leading to a reduction in maximum uptake when compared with that of a diagnostic activity of radioiodine. more...

Objective: Some patients with relapsed differentiated thyroid cancer may show rising thyroglobulin (Tg) levels despite a lack of 131I uptake on routine whole body imaging. A significant proportion of these patients, after therapy doses of 131I, may demonstrate positive 131I uptake with a subsequent fall in serum Tg, implying a therapeutic effect. Attempts to identify such patients by increasing the dose of the diagnostic 131I tracer may lead to inhibition of subsequent uptake after the therapy dose, an effect referred to as 'stunning' and associated with a reduction in therapeutic effect. 123I is a short half-life gamma-emitter, thought to be unlikely to cause stunning, which may thus be more suitable than 131I for diagnostic imaging of thyroid cancer., Design and Patients: The efficacy of the 123I radionuclide was determined in a longitudinal study of 12 patients who were selected only because they showed elevated serum Tg and a negative diagnostic 131I whole body study prior to therapy with 131I., Results: There was almost complete concordance in uptake between 123I diagnostic imaging and the final scans carried out after 131I therapy (hereafter known as therapy studies) in 11 out of 12 patients at their first evaluation, in each of four patients receiving 123I at their second evaluation and in a single patient receiving 123I at a third evaluation. One patient had a positive 123I study but a negative 131I therapy study: following therapy Tg declined from 5.5 pg/l to undetectable levels, implying a therapeutic effect, and suggesting that the negative uptake was not the result of stunning. Two negative diagnostic 123I studies were followed by negative therapy studies, and thus there were no false negatives. 123I correctly identified disease in the nine patients with metastases in the lungs, mediastinum and bone at the first evaluation, in all four patients at the second evaluation and in the single patient at the third evaluation. At the end of the study, patients had received up to three 131I therapy doses, Tg had risen in four patients, fallen in eight and become undetectable in one patient., Conclusions: 123I is highly sensitive in diagnosing local recurrence and metastatic disease, and produces scintigraphic images which concord well with uptake following 131I therapy. It is proposed that 123I imaging, in combination with serum Tg measurements, should replace 131I tracer imaging as an indicator of the potential efficacy of 131I therapy. Stunning, with its detrimental effects on 131I therapy, may thus be avoided. The possibility of false negative images due to the stunning phenomenon must always be borne in mind if there is a discrepancy between positive 131I imaging studies and a surprisingly negative subsequent 131I therapy scan. more...

Radioiodine therapy is used in the treatment of patients with differentiated thyroid cancer both to ablate residual thyroid tissue after initial surgery and to treat residual, recurrent, or metastatic cancer. In most institutions, therapy remains based on empirically determined, fixed amounts of radioiodine that do not account for individual differences in the mass of tissue to be treated and in radioiodine kinetics. Over the last 25 years, we have developed and refined techniques based on pre-therapy, diagnostic quantitative radiation dosimetry and imaging with 131I that permit individualized treatment which balances the success of the treatment and the risk of serious acute adverse effects on the bone marrow and lungs. In this manuscript we discuss patient selection and preparation for radioiodine therapy and outline in detail methods for performing quantitative dosimetry studies. Guidelines for the application of these results to the treatment of individual patients are presented. more...

False-positive radioiodine uptake has been reported in many organ systems. We describe a female patient who had mixed papillary and follicular thyroid carcinoma, and on radioiodine total-body imaging demonstrated focal, lower-right chest uptake. Special prone imaging with the right breast dependent proved that the uptake was inside the right breast. Review of a recent breast ultrasound and mammograms showed this uptake to correspond to a large breast cyst. It is known that 131I breast uptake may be functional within the mammary gland. In this patient, it was due to retention within the cyst after the background activity decreased. Knowledge of this phenomenon may improve the interpretation of total-body 131INa studies. more...

Unlabelled: In this study, 27 patients less than 18 yr old with pulmonary metastases from well-differentiated thyroid carcinoma were evaluated to determine their response to (131)I therapy., Methods: Of 121 children and adolescents treated with (131)I between 1963 and 1996, 27 patients had pulmonary metastases associated with nodal disease. Treatment response from (131)I was measured by three parameters: chest radiograph, scintigraphic images and serum thyroglobulin levels. Total activity of (131)I administered ranged from 4.6 GBq (125 mCi) to 38.7 GBq (1.05 Ci). Four patients were given one treatment, 8 were given two treatments, 4 were given three treatments and 11 were given more than three treatments. Radiation doses to the lungs were estimated in 14 patients using the MIRD methodology. The minimum duration of follow-up was 6 mo., Results: At the time of initial presentation, diagnostic (131)I studies revealed bilateral radioiodine uptake in the lungs in 19 (70.4%) patients, whereas 12 (44.4%) patients had abnormal chest radiographs. One patient was lost to follow-up and was excluded from the study. Of the 26 patients studied, complete ablation of pulmonary metastases was observed in 8 (30.8%), partial ablation in 17 (65.4%) and there was no response to treatment in 1 (3.8%). Dosimetric parameters such as radioiodine uptake as a percentage of therapeutic activity, effective half-life and radiation dose delivered to the lungs were evaluated with each therapy. There was a progressive decline in each of these parameters with successive therapies. No correlation was observed between the radiation dose delivered and the response of pulmonary metastases to therapy. The number of therapies and amount of radioiodine administered had no influence on the ablation response. Of the 26 patients, 13 had a follow-up duration of less than 5 yr, 7 had 5-10 yr and 6 had more than 10 yr. One patient developed new metastases after 7 yr of diagnosis and treatment. One patient died of the disease after 4 yr. All surviving patients were asymptomatic and leading normal lives., Conclusion: Complete response of pulmonary metastases after (131)I therapy is difficult to achieve. A partial response with reduction of metastatic disease is possible and, in general, the patients had a good quality of life with no further disease progression and a low mortality rate. more...

Unlabelled: The therapeutic outcome after (131)I first ablative treatment in patients operated on for nonmedullary differentiated thyroid carcinoma was compared after both the currently used scanning dose of 111 MBq (131)I and a scanning dose of 37 MBq (131)I., Methods: Two-hundred twenty-nine consecutive patients with no known metastases were retrospectively studied. They were divided in two populations according to the scanning dose (127 patients with 111 MBq and 102 patients with 37 MBq). All patients received 111 or 37 MBq (131)I for diagnostic purposes and 3.7 GBq (131)I for ablative therapy 9 days later. To assess the efficacy of the treatment, all patients were studied with (131)I and with thyroglobulin plasma assays 6-17 mo later., Results: Successful outcome was significantly more frequent after a scanning dose of 37 MBq (131)I than after a scanning dose of 111 MBq (76% versus 50%, p < 0.001). The treatment efficacy was particularly enhanced after 37 MBq in patients with associated lymphocytic thyroiditis., Conclusion: In patients with no known metastases, our data suggest that the impairment of the treatment efficacy observed after a scanning dose of 111 MBq (131)I is related to a stunning effect on the thyroid remnants. The threshold amount above which this effect begins to occur in thyroid remnants could be between 37 and 111 MBq (131)I. Consequently, a scanning dose of only 37 MBq (131)I could be recommended before first ablative treatment. The absence of metastatic patients in our study prevents any conclusion about the possible stunning of the neoplastic tissue. Nevertheless, we must suspect such an effect and try to avoid it, especially during follow-up after first radioiodine therapy. For instance, one may consider postponing radioiodine treatment several weeks or even months after scanning dose administration or using only thyroglobulin measurement for patients who are likely to receive a subsequent radioiodine treatment. more...

Radioactive iodine (131I) has been found to be more sensitive and more specific than thallium-201 for the detection of distant metastases and thyroid remnants in the neck in cases of well-differentiated thyroid carcinoma. 201Tl has been deemed particularly useful in localizing metastases or recurrence in patients with a negative 131I scan and abnormal levels of serum thyroglobulin (Tg). This study aimed to: (1) determine the value of 201Tl imaging in localizing metastases or recurrence in patients with well-differentiated thyroid carcinoma, and (2) evaluate the false-positive and false-negative results of 131I and 201Tl scintigraphy. Sixty-two thyroid remnant ablated patients who underwent simultaneous postoperative 201Tl and 131I scans and and serum Tg determinations were evaluated. Fifty patients had papillary thyroid carcinomas and 12 had follicular thyroid carcinomas. 201Tl imaging was performed before the 131I studies. Of the 62 patients who underwent 201Tl imaging studies, 24 were found to have positive results, with local recurrence or distant metastases. Patients with positive results in the 201Tl imaging studies tended to be older, were mor often male, had higher Tg levels and had a higher recurrence rate. Of these 24 patients, ten had negative diagnostic or therapeutic 131I scans. Concurrently, serum Tg levels were less than 5 ng/ml in five of these ten patients. Three patients were deemed false positive by 201Tl scans; one had a parotid tumour, one a periodontal abscess and one lung metastasis. Among the 38 patients with negative 201Tl scans, 11 had positive findings on 131I scans. Three had distant metastases: two with lung metastases and one with bone metastases. Patients with false-positive results on 131I scans included those with biliary tract stones, ovarian cysts, and breast secretion. Of the 27 patients with negative 201Tl and 131I scans, 15 had elevated serum Tg levels. Among these, local recurrence followed by lung metastases was manifested in a 49-year-old male with papillary thyroid carcinoma. In conclusion, both 131I and 201Tl scans are useful in the detection of recurrence or distant metastasis of well differentiated thyroid cancers. 201Tl scan could in particular be used in patients with a negative 131I scan in conjunction with an elevated Tg level. more...

The uptakes of thyroablative doses of 131I by postoperative thyroid remnants and/or thyroid carcinoma metastases following diagnostic surveys with 131I or 123I were retrospectively compared by visual inspection. Only those patients with a diagnostic scan demonstrating functioning tissue, remnant, and/or metastasis, following thyroidectomy for differentiated thyroid carcinoma, were evaluated. The 131I survey group (n = 26) had received a diagnostic dose of 3 to 10 mCi of 131I. The 123I group (n = 14) had received the usual diagnostic dose of 300 microCi of 123I. The age, sex, and tumor type in the two groups were not statistically different. The uptake of the ensuing thyroablative dose of 131I appeared, by visual inspection, to be impaired in 20 of 26 patients in the 131I group and in none of the 14 patients in the 123I group (p < 0.00003). In the 131I group there was suggestion of a dose-response, that is, the higher the administered activity of 131I for the diagnostic scan, the more reduced was the subsequent apparent uptake of the thyroablative dose (p = 0.0007). Thyroid remnants or cervical lymph node metastases appeared to be affected more frequently than were the distant (pulmonary or skeletal) metastases (p = 0.004). This study suggests that iodine uptake function may be suppressed by the absorbed radiation from the 3 to 10 mCi "diagnostic" scanning dose of 131I. In this regard, 123I may be a better initial diagnostic agent to be used prior to radioablation therapy. more...