Residual Thyroid Tissue Research Articles

Surgical anatomy of the pyramidal lobe in cancer patients: A Prospective Cohort in a Tertiary Centre

IntroductionTo study the characteristics of pyramidal lobe (PL) in cancer patients with emphasis on its involvement in patients subjected to thyroidectomy at a tertiary care cancer centre. MethodsRetrospective review of prospectively maintained data of 103 patients (33 males and 70 females) who underwent thyroidectomy from January 1st 2011–August 31st 2013. Surgery was performed by single surgeon, findings recorded by the lead author and all measurements taken with specimen in situ prior to mobilization of thyroid gland with intact anatomy. Thyroid specimens were examined for presence, location, length and histology of PL. ResultsPL was identified in 38 (36.89%) patients. PL was commoner on left 27 (71.05%) compared to 11 (28.95%) on right side. The frequency of PL was higher in males 51.51% compared to females 30%. The length varied from 4 to 35 mm. The mean length was 18.0 ± 12.4 mm. In 10.53% cases PL contained deposits of papillary carcinoma of thyroid. DiscussionMeticulous clearance of disease is of utmost importance in thyroid cancer surgery in order to prevent recurrence and ensure reliable follow up with serum thyroglobulin. PL is a common site of residual thyroid tissue which if involved by cancer can be a cause of local recurrence. ConclusionsPL is a well established entity which is present in over one third of patients. Efforts should be made to identify PL during surgery given its bearing on the management of thyroid carcinoma as nearly 10% of these will be site of multifocal papillary carcinoma.

Is radioiodine administration in patients with papillary thyroid multifocal microcarcinoma unnecessary?

SummaryRadioiodine (RAI) has played a crucial role in differentiated thyroid cancer treatment for more than 60years. However, the use of RAI administration in patients with papillary thyroid microcarcinoma (even multifocal) is now being widely discussed and often not recommended. In accordance with European consensus, and contrary to the American Thyroid Association (ATA) guidelines, we recently performed RAI thyroid remnant ablation in a patient with differentiated papillary multifocal microcarcinoma. The post-therapeutic whole-body scan and SPECT/CT revealed the real and unexpected extent of disease, with metastases to upper mediastinal lymph nodes. This finding led to the patient’s upstaging from stage I to stage IVa according to the American Joint Committee on Cancer/International Union Against Cancer criteria.Learning points131I is a combined beta–gamma emitter, thus allowing not only residual thyroid tissue ablation but also metastatic tissue imaging.RAI remnant ablation omission also means post-treatment whole-body scan omission, which may lead to disease underestimation, due to incorrect nodal and metastatic staging.RAI should be considered also in “low-risk” patients, especially when the lymph node involvement is not reliably documented.Lower administered RAI activity (30mCi, 1.1GBq) may be a workable compromise in low-risk patients, not indicated for RAI remnant ablation according to ATA guidelines.

Evaluation of ablation of thyroid remnants with 1850 MBq iodine-131 in 67 patients with thyroid cancer.

Radioiodine remnant ablation (RRA) is used to destroy residual normal thyroid tissue after total thyroidectomy in differentiated thyroid carcinoma (DTC) patients. As 1850-MBq RRA is routinely performed at our facility, we evaluated the outcomes. Sixty-seven DTC patients without macroscopic residual lesions after total thyroidectomy were evaluated. Thyroglobulin (Tg) was measured 2-3 months before RRA with thyroxin administration (pretreatment); just before ablation after a 3-week iodine intake restriction with thyroxin withdrawal (THW) (N.=16) or recombinant human thyroid-stimulating hormone (rhTSH) stimulation (N.=51); and 3 months after RRA, after a 2-week iodine intake restriction and 3-week THW (N.=57) or rhTSH stimulation (N.=10). All patients received 131I (1850 MBq) treatment followed by 131I scintigraphy about 8 days later (8.18±0.91) and 131I scintigraphy (185 MBq) after the dosage 24 hours later 3months after RRA. Initial RRA goal was defined as negatively visible uptake in 131I thyroid bed (VUT) and a Tg level of <2 ng/mL 3 months after RRA. Rest 60 patients whose TSH levels were below 0.5 µIU/mL of all 67 patients were evaluated. Negatively VUT on 3 months after RRA was shown in 56 out of 60 patients (93.3%). Initial RRA goal was achieved in 21 (42.0%) of 50 patients, excluding 3 patients whose Tg levels 3 months after RRA were not measured and 7 patients with anti-Tg antibodies. Pretreatment Tg levels (P=0.0003) was significant predictive factor for Initial RRA goal on multivariate logistic regression analysis. RRA with 1850 MBq is effective by visual diagnosis, about 40% of all intermediate or high-risk DTC patients achieved initial RRA goals by both visual and Tg levels diagnosis.

Significance of Low Levels of Thyroglobulin Autoantibodies Associated with Undetectable Thyroglobulin After Thyroidectomy for Differentiated Thyroid Carcinoma.

The management of patients with differentiated thyroid carcinoma (DTC) showing low levels of serum thyroglobulin autoantibodies (TgAb) and undetectable Tg after thyroidectomy is unsettled. This study sought to elucidate the clinical significance of low levels of TgAb and to evaluate their interference with Tg measurement in vitro. Tg and TgAb levels were correlated with the post-thyroidectomy staging of 177 consecutive DTC patients undergoing (131)I ablation after total thyroidectomy (clinical study). Tg was measured by an immunometric assay (functional sensitivity: 0.1 ng/mL), and TgAb were evaluated by six assays (functional sensitivities: 1.2-96 IU/mL; positive cutoffs: 4-150 IU/mL). The changes in Tg concentration (Tg recovery) of diluted specimens from DTC patients were also measured after incubation with 67 sera from DTC patients with undetectable Tg and low levels of TgAb (in vitro study). DTC sera containing Tg were diluted serially (from 330 to 0.1 ng/mL) and incubated with TgAb samples; Tg was then measured. In the clinical study: all patients had residual thyroid tissue, and 10 had metastatic disease. Depending on the TgAb assay, median Tg values were 7.0-10.9, 0.0-5.3, and 0.0-0.0 ng/mL in patients with undetectable, borderline (between functional sensitivities and positive cutoffs), and positive TgAb, respectively (p < 0.001). An undetectable Tg value was associated with borderline levels of TgAb in five assays. Only two patients with metastatic disease had undetectable Tg; both were TgAb positive by three or more assays. Conversely, no patient with undetectable Tg and undetectable or borderline TgAb by sensitive assays had metastatic disease. In the in vitro study, TgAb interfered significantly with Tg recovery (p < 0.001), but low levels of TgAb did not abolish Tg recovery. While low levels of TgAb do not preclude Tg measurement in vitro, they can be associated with an undetectable Tg in DTC patients with residual thyroid tissue after thyroidectomy. However, the finding of low levels of TgAb by sensitive assays associated with an undetectable Tg rules out metastatic disease.

Evaluation of the highly sensitive Roche thyroglobulin II assay and establishment of a reference limit for thyroglobulin-negative patient samples

ObjectivesThyroglobulin (Tg) measurements are used to monitor for residual thyroid tissue in patients with differentiated thyroid cancer (DTC) after thyroidectomy and radioiodine ablative therapy. In recent years highly sensitive Tg assays have been developed. In this study the analytical performance of the new Roche Elecsys Tg II assay was evaluated and compared with the well documented Access2 Tg assay (Beckman–Coulter). Design and methodsAnalytical performance was examined using various Clinical and Laboratory Standards Institute (CLSI) evaluation protocols. Tg negative patient sera were used to establish an upper reference limit (URL) for the Elecsys Tg II assay. ResultsNon-linearity, drift and carry-over according to CLSI EP10 and EP6 in a measuring range of 0.04–500ng/mL were non-significant. Total precision according to CLSI EP5 was 10% at a Tg concentration of 0.08ng/mL. A patient serum comparison performed according to a modified CLSI EP9 protocol showed a significant difference of a factor of approximately 1.4, despite using an identical CRM calibrator. The Elecsys Tg II assay measured Tg with a two-fold higher sensitivity than the Access2 assay. Finally, using human sera without Tg, an URL of 0.05ng/mL was determined. ConclusionsIn our hands the highly sensitive Elecsys Tg II assay shows a good analytical performance and a higher sensitivity compared to the Access2 Tg assay. An URL of 0.05ng/mL for the Elecsys Tg II assay was determined which may improve the clinical utility of the assay for the detection of residual DTC or disease recurrence.

False positive diagnosis on (131)iodine whole-body scintigraphy of differentiated thyroid cancers.

(131)Iodine is used both to ablate any residual thyroid tissue or metastatic disease and to obtain whole-body diagnostic images after total thyroidectomy for differentiated thyroid cancer (DTC). Even though whole-body scan is highly accurate in showing thyroid residues as well as metastases of DTC, false positive results can be found, possibly leading to diagnostic errors and unnecessary treatments. This paper reviews the physiological and pathological processes involved as well as the strategy to recognize and rule out false positive radioiodine images.

Clinical value of 99Tcm-MIBI scintigraphy in patients with differentiated thyroid carcinoma after surgery and first 131I therapy

Objective To evaluate the clinical value of 99Tcm-MIBI scintigraphy for diagnosis of residual thyroid tissue and metastasis in patients with DTC after their first 131I therapy. Methods From February 2010 to March 2014, 192 DTC patients (38 males, 154 females, average age (43.2±8.6) years) who received total or near-total thyroidectomy and were pathologically diagnosed as DTC (171 papillary and 21 follicular carcinomas) underwent 99Tcm-MIBI scan (average dosage: 740-925 MBq) 6 months after their first 131I therapy. 131I scans was performed 4 d after oral administration of 131I of therapeutic dose (average dosage: 5 550-8 140 MBq). Pre- and post-therapeutic images and the serum Tg level (detected before the imagings) were compared and analyzed. Any abnormal uptake of agent found inside or outside the thyroid was regarded as positive result. Patient-based and lesion-based data analysis were performed by χ2 test and two-sample t test. Results A total of 191 patients were finally included, of which 65 positive cases were found. The sensitivity of 99Tcm-MIBI imaging was significantly lower than that of 131I imaging(56.9% (37/65) vs 92.3%(60/65); χ2=14.7, P 0.05). The serum Tg level of positive groups (99Tcm-MIBI positive + 131I positive or 131I negative) were significantly higher than that of 99Tcm-MIBI negative + 131I negative group (t=-20.7 and -6.0, both P<0.01), and that of 99Tcm-MIBI positive + 131I negative group was higher than that of 131I positive + 99Tcm-MIBI negative group(t=-2.7, P<0.05). Conclusion 99Tcm-MIBI imaging could detect metastasis of DTC patient after first radioiodine therapy, but the value in detecting thyroid remnants is limited. Key words: Thyroid neoplasms; Radiotherapy; Iodine radioisotopes; Radionuclide imaging; MIBI

Effect of 131I 'clear residual thyroid tissue' after surgery on the function of parathyroid gland in differentiated thyroid cancer.

Thyroid cancer is a common malignant tumor of the endocrine glands. Although surgery is the optimal treatment utilized, the disease is characterized by recurrence and metastasis. The aim of the present study was to determine the effect of iodine-131 (131I) ‘clear residual thyroid tissue’ following surgery on the treatment of differentiated thyroid cancer (DTC) and its effect on the function of the parathyroid gland. A total of 160 patients diagnosed with DTC, who were consecutively admitted to our Hospital between June 2012 and June 2014 and underwent total thyroidectomy or subtotal resection, were included in the present study. After three months, the patients were administered 131I ‘clear residual thyroid tissue’ treatment and underwent a whole body scan after 1 week to determine whether ‘clear residual thyroid tissue’ treatment was successful or not. The treatment was repeated within 3 months if not successful. Of the 160 patients, 24 patients had cancer metastasis (15.0%). The average dose of 131I used for the first time was 6.4+1.2 GBq and the treatment was successful in 66 cases (41.3%). The average treatment time was 2.8±0.6 therapy sessions. The results showed that, prior to and following the first treatment and at the end of the follow up, levels of the parathyroid hormone, serum calcium and phosphorus were compared, and no statistically significant difference (P>0.05) was observed. There were 5 patients with persistent hypothyroidism and 8 patients with transient hypothyroidism. The levels of thyroglobulin were significantly decreased, and the difference was statistically significant (P<0.05). A total of 48 patients (30%) with hypothyroidism were identified. In conclusion, the results have shown that DTC resection and 131I ‘clear residual thyroid tissue’ treatment did not significantly impair the parathyroid function, thereby improving the treatment effect.

Oncocytic parathyroid adenoma

IntroductionFine-needle aspiration cytology (FNAC) of thyroid nodules commonly reveals the presence of oncocytic cells (or Hurthle cells) in a follicular neoplasm. Histological examination is necessary to determine the benign or malignant nature of the tumour. However, oncocytic cells are also normally present in the parathyroid glands. Case reportA thyroid nodule was discovered on thyroid ultrasound in a woman with a history of left partial thyroid lobectomy. Fine-needle aspiration cytology revealed a follicular neoplasm comprising oncocytic cells (Hürthle cells). This woman also presented features of hyperparathyroidism with hypercalcaemia. 123I/99mTc-sestamibi and 18F-fluorocholine PET-CT scan revealed increased uptake over the remaining left thyroid lobe. Left lobectomy was completed together with thyroid exploration. Histological examination revealed a parathyroid adenoma in the residual thyroid tissue. Parathyroid hormone levels subsequently returned to normal. DiscussionCytomorphological similarities are often observed between parathyroid and Hürthle cell thyroid tumours. The parathyroid rather than thyroid nature of the tumour must be strongly suspected preoperatively in the presence of hyperparathyroidism.

Bilateral Truncal Ligation of the Inferior Thyroid Artery during Bilateral Subtotal Thyroidectomy Causes a Decrease in Parathormone without Clinically Manifest Hypoparathyroidism: A Randomized Clinical Trial

Background: Bilateral truncal ligation (BTL) of the inferior thyroid artery (ITA) is frequently used during subtotal thyroidectomy to reduce the risk of post-operative bleeding as well as to reduce the blood loss intra-operatively. However, its effect on parathyroid function has not been evaluated in relation to age, residual and resected thyroid volume. Methods: A total of 83 patients were randomized to receive non-BTL or BTL. After bilateral resection, the residual thyroid tissue on each side was measured by intra-operative ultrasonography. Laboratory and clinical examinations were performed the day before operation, intra-operatively and on post-operative days 2 and 5. The primary outcome measure was the difference in intact parathormone (PTHi) on post-operative day 5. Secondary outcomes were laboratory-diagnosed hypocalcaemia or hypoparathyroidism and clinically manifest hypoparathyroidism, respectively. Results: PTHi on post-operative day 5 was significantly lower in the BTL group (29.4 vs. 34.7 ng/l in the non-BTL group, p = 0.033), especially in 61- to 80-year-old patients (0 vs. -7.91 ng/l, p = 0.029). The biggest decline in PTHi was found in the BTL group (-14.067 ng/l PTH, p = 0.018) with a residual thyroid volume of 0.5-1.9 ml. There were two cases of asymptomatic hypoparathyroidism in each group (5.1 vs. 4.8%, respectively, p = 1.000). The only case of clinically manifest hypoparathyroidism was in a BTL group patient aged 64 years (2.4%, p = 1.000). Conclusion: BTL of the ITA during subtotal thyroidectomy causes a larger decrease in PTH but does not lead to a significantly higher rate of clinically manifest hypoparathyroidism. BTL of the ITA, age >61 years, and a very small thyroid remnant (<2 ml) may be risk factors for post-operative hypoparathyroidism.

Efficacy analysis of first radioiodine (131I) ablation in post-surgical differentiated thyroid carcinomas

Objective To investigate the efficacy of the first radioiodine (131I) ablation of residual thyroid on differentiated thyroid carcinomas after surgery and to analyze the influential factors for efficacy. Methods All 91 differentiated thyroid carcinoma (DTC) patients were treated with 131I after surgery. According to pathologic types of the tumor, surgical options, and time interval between surgery and radioiodine treatment, patients were divided into different groups, then the efficacy was observed. Results Fifty of 91 patients (54.9%) achieved successful thyroid remnant ablation after the first dose. The success rate of first ablation of residual thyroid tissues had no relationship with the pathologic type of the tumor(P>0.05). While it was statistically related to the surgical options, among which patients undertaking the total thyroidectomy possessed the highest success rate (79.3%)(P<0.05). Ninety one patients were divided into 3 groups according to the time interval between surgery and radioiodine ablation: group less than 3 months (3M group), group from 3 to 12 months (3~12 M group), group beyond 12 months (12M). Among them, the 3M group possessed the highest success rate (68.0%)(P<0.05). Conclusions There would be better effect of the first ablation of residual thyroid tissues with total thyroidectomy, ablation conducted within 3 months after surgery. Key words: Thyroid neoplasms/SU/RT; Iodine radioisotopes/TU

Radioiodine Remnant Ablation: A Critical Review.

Radioiodine remnant ablation (RRA) is considered a safe and effective method for eliminating residual thyroid tissue, as well as microscopic disease if at all present in thyroid bed following thyroidectomy. The rationale of RRA is that in the absence of thyroid tissue, serum thyroglobulin (Tg) measurement can be used as an excellent tumor marker. Other considerations are like the presence of significant remnant thyroid tissue makes detection and treatment of nodal or distant metastases difficult. Rarely, microscopic disease in the thyroid bed if not ablated, in the future, could be a source of anaplastic transformation. On the other hand, microscopic tumor emboli in distant sites could be the cause of distant metastasis too. The ablation of remnant tissue would in all probability eliminate these theoretical risks. It may be noted that all these are unproven contentious issues except postablation serum Tg estimation that could be a good tumor marker for detecting early biochemical recurrence in long-term follow-up strategy. Radioactive iodine is administered as a form of “adjuvant therapy” for remnant ablation. There have been several reports with regard to the administered dose for remnant ablation. The first report of a prospective randomized clinical trial was published from India by a prospective randomized study conducted at the All India Institute of Medical Sciences, New Delhi in the year 1996. The study reported that increasing the empirical 131I initial dose to more than 50 mCi results in plateauing of the dose-response curve and thus, conventional high-dose remnant ablation needs critical evaluation. Recently, two important studies were published: One from French group and the other from UK on a similar line. Interestingly, all three studies conducted in three different geographical regions of the world showed exactly similar conclusion. The new era of low-dose remnant ablation has taken a firm scientific footing across the continents.

Low and High Radio-Iodine-131 Doses in Postoperative Ablation in Differentiated Thyroid Carcinoma

The goals of post-surgical RAI therapy in patients with differentiated DTC are to ablate residual normal thyroid tissue that may facilitate surveillance,) Also the potential tumoricidal effect on residual microscopic RAI-avid disease, and to provide a posttreatment whole-body scan that may reveal undetected local or distant metastases.Although, these goals are important, the ultimate endpoint of postsurgical ablation is to minimize DTC recurrence and death by eliminating residual normal thyroid tissue or residual microscopic disease that could be a focus for future recurrence(1). Successful RAI-131 thyroid remnant ablation is associated with better prognosis with regard to both recurrence-free and overall survival, lower rates of distant metastases, and reduced cancer mortality rates, compared with only surgery or surgery and L-thyroxin therapy alone (2). It also facilitates long-term follow up of patients with DTC. It was shown byVerburg et al. that a successful ablation itself seems to be a highly important prognostic factor for long-term outcome. They found that the patients with a successful ablation, 87% were still free of the disease after 10 years, whereas of the patients with an unsuccessful ablation, only 50% were free of disease with thyroid cancer-related survival was (93% versus 78%) (P > 0.001)(3). After four decades of follow-up, based on regression modeling of 1510 patients without distant metastases at the time of initial therapy,Mazzaferri and Kloos found thyroid remnant ablation to be an independent variable that reduced loco regional recurrence, distant metastases, and cancer death. A similar observation has also been made by the National Thyroid Cancer Treatment Cooperative Study group (4), they had reconfirmed that postoperative RAI treatment was associated with improved cancer-specific mortality rates and reduced disease progression in both papillary and follicular cancer(5).

RAI thyroid bed uptake after total thyroidectomy: A novel SPECT-CT anatomic classification system.

Recent, more selective use of radioactive iodine (RAI) has led to reevaluation of the clinical importance of achieving complete total thyroidectomy with minimal residual normal thyroid tissue. We utilize the improved localization by post-RAI remnant ablation, single photon emission computerized tomography-computed tomography (SPECT-CT) to define specific anatomic sites of residual RAI-uptake foci after total thyroidectomy for differentiated thyroid cancer (DTC) and to provide a novel classification system relating uptake to thyroid anatomy and preservation of adjacent neural structures. Retrospective. Radioactive iodine-uptake foci in thyroid bed were localized by SPECT/CT imaging at the time of RAI remnant ablation in 141 DTC patients undergoing total thyroidectomy. Minimal residual RAI uptake (median 0.32% at 24 hours) in the thyroid bed was detected by diagnostic planar whole body scans in 93% and by posttherapy SPECT/CT imaging in 99% of subjects. Discrete RAI uptake foci were identified on the SPECT/CT imaging at Berry's ligament (87%), at superior thyroid poles (79%), in paratracheal-lobar regions (67%), in isthmus-region (54%), and in pyramidal lobe (46%). Despite the residual foci, the nonstimulated thyroglobulin (Tg) prior to remnant ablation (with a median thyroid-stimulating hormone of 0.36 m IU/L) was < 0.6 ng/mL in 53% and < 1 ng/mL in 73% of cases. After extracapsular total thyroidectomy, highly sensitive detection tools identify microscopic residual RAI avid foci in thyroid bed in the majority of patients. These foci can be classified as 1) neural-related and 2) capsule-related. These common residual foci have no relationship to postoperative Tg, suggesting that attempts at radical removal of thyroid tissue in these locations may not be warranted. 4.

Monitoring of the patients operated on nodular goiter and features of the operated thyroid gland functional state depending on the surgical intervention extent

The paper presents some data about a monitoring of the changes in the thyroid residue: hormonal status, antibody rate depending on the scope of nodular goiter surgical treatment. It was established that 2 months after the surgery the autoimmune process becomes more active, the intensity of which gradually fades to the 6th and 12th months of post-operative intervention. It should be noted that a compensatory growth of the residual thyroid tissue after the surgery was observed.

Predictive Factors of Malignancy in Residual Thyroid Tissue after Partial Thyroidectomy in Patients with Differentiated Thyroid Cancer

Abstract Although partial thyroidectomy has lower operative risk, it potentially caries the risk of leaving residual malignancy. The aim of this study was to establish malignancy rate in residual thyroid tissue in patients with differentiated thyroid cancer (DTC) who underwent partial thyroid surgery and subsequently had completion thyroidectomy. We also investigated a number of clinical and biochemical factors that may anticipate the presence of malignancy in the thyroid remnant. Data of 58 patients with DTC who underwent completion thyroidectomy were retrospectively analyzed. Patients were divided into 2 groups based on the residual tissue pathology after completion thyroidectomy; the first group consisted of patients with malignant residual tissue, and the second group consisted of patients with benign residual tissue. Tumor histopathology type and serum thyroglobulin levels before completion thyroidectomy were compared between the two groups. Among 58 patients, 13 (22.4%) patients were found to have malignant residual tissue after completion thyroidectomy. No significant differences were found between the groups with respect to age, serum thyroglobulin level before completion thyroidectomy, primary tumor type, tumor size, bilateralism, multifocality, arterial invasion, thyroid capsular invasion, and extrathyroidal invasion. Residual thyroid volume was higher in patients with malignant residual tissue. In binary logistic regression analysis, residual thyroid volume was the only predictor factor for the presence of malignancy in the thyroid remnant. Malignancy in residual thyroid tissue is not uncommon. Thyroid remnant volume may be predictive of malignancy in residual thyroid tissue. Keywords: Thyroid cancer, completion thyroidectomy, residual thyroid tissue

Bronchiectasis Masquerading as Lung Metastasis in a Patient with Papillary Carcinoma Thyroid Identified by 131I Whole Body Scintigraphy

Differentiated thyroid carcinoma (DTC), arising from thyroid follicular epithelial cells, accounts for the vast majority of thyroid cancers. Despite being well-differentiated, papillary thyroid cancers may be overtly or minimally invasive. They may invade lymphatics but are less likely to invade blood vessels. Iodine-131 (131I) is routinely used to image patients after thyroidectomy to assess the presence of residual thyroid tissue with or without metastasis. False positive 131I scans, showing the presence of 131I uptake in the absence of residual thyroid tissue or metastases can occur, although they are uncommon. Unless recognized as a false positive, 131I uptake may result in diagnostic error and lead to administration of an unnecessary higher therapeutic dose. We present a 55 year old female, histopathologically proven case of follicular variant of papillary carcinoma that underwent Total Thyroidectomy. Residual thyroid and whole body scan showed moderate residual thyroid tissue with abnormal 131I in right lung masquerading as right lung metastases. SPECTCT (single photon emission computed tomography – computed tomography) was incremental in localizing the site of 131I uptake to bronchiectatic changes. 131I diagnostic and post therapy scans are useful to risk stratify DTC patients’ so that amount of high dose 131I to be administered to patient can be estimated and judiciously used in their treatment.

Rate of thyroglossal duct remnant visualization after total thyroidectomy for differentiated thyroid carcinoma and its impact on clinical outcome of radioactive iodine (I-131) ablation.

Objectives:The rate and impact of thyroglossal duct remnant (TGDR) visualization in patients with hypothyroidism after total thyroidectomy for differentiated thyroid carcinoma (DTC) have not yet been fully determined. The aim of this study was to assess the rate of TGDR visualization in post total thyroidectomy whole body scan (WBS) for DTC and to evaluate its impact on the outcome of I-131 ablation.Methods:A total of 60 consecutive DTC patients (51 papillary thyroid Ca., and 9 Follicular thyroid Ca.), underwent total thyroidectomy, followed by WBS (using I-131 in 28 patients and I-123 in 32 patients), neck ultrasound (US), thyroglobulin (Tg) and Tg anti-bodies (TgAb) assay after 40 days and subsequent I-131 ablation. At 6 months later follow-up I-131 WBS, neck U/S, Tg and TgAb were performed following suspension of L-thyroxine for 1-month (thyroid stimulating hormone [TSH] >30 μIU/ml) in 53 patients and following recombinant human TSH stimulation in seven patients.Results:Of the studied 60 patients, 19/60 (31.7%) had a linear or focal radioactivity at the superior midline of the neck, suggesting TGDR (Group 1), and 41/60 (68.3%) had no uptake to suggest TGDR (Group 2). No significant difference regarding age, gender and histopathology between both groups. Neck US showed no evidence of thyroid tissue in the superior midline of the neck in both groups, and only a small or no residual thyroid tissue in patients of Group 1. There was a significant successful I-131 ablation rate among patients of group 1 compared to group 2 (79% in Group 1 vs. 41.5% in Group 2) (P = 0.007).Conclusions:Thyroglossal duct remnant visualization on WBS of hypothyroid subjects after total thyroidectomy suggests presence of only a small or no residual functioning thyroid tissue at the thyroid bed and can predict a good response to I-131 ablation.

Iodine-131 induces apoptosis in HTori-3 human thyrocyte cell line and G2/M phase arrest in a p53-independent pathway.

Iodine‑131 is known to destroy residual thyroid tissue following surgical resection of differentiated thyroid carcinoma and is widely used to treat hyperthyroidism. However, the mechanism by which iodine‑131 induces apoptosis and cell cycle arrest in the human thyrocyte cell line, Htori‑3, remains to be elucidated. In the present study, the cytotoxic effect of iodine‑131 on the HTori‑3 cell line and the underlying mechanism of iodine‑131‑induced cell apoptosis were investigated. Cell viability was analyzed using an MTT assay, while cell apoptosis and cell cycle arrest were determined using flow cytometry. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blot analyses were performed to determine the changes in the expression levels of p53, B‑cell lymphoma 2 (Bcl‑2), Fas and growth arrest and DNA damage‑inducible 45 (GADD45), following iodine‑131 treatment. The results demonstrated that iodine‑131 may inhibit HTori‑3 cell growth via cell apoptosis and G2/M phase arrest in a time‑ and dose‑dependent manner. The iodine‑131 dose required for 50% growth inhibition of HTori‑3 cell viability 48 h after treatment was 27.75±2.22 MBq/ml. Upregulation of Fas and downregulation of Bcl‑2 expression levels were observed following iodine‑131 treatment. The results of RT‑qPCR revealed an increase in the GADD45 mRNA expression following HTori‑3 cell exposure to iodine‑131. Notably, the mRNA and protein expression levels of p53 were not altered following iodine‑131 treatment. In conclusion, iodine‑131 may induce apoptosis in HTori‑3 cells by downregulating the expression of Bcl‑2 and upregulating the expression of Fas. In addition, iodine‑131 may upregulate GADD45 mRNA expression in HTori‑3 cells, resulting in G2/M phase arrest in a p53‑independent pathway.

Cardiac blood pool activity on postablation radioiodine imaging.

There are reports on physiologic and pathologic mediastinal uptake on radioiodine imaging in patients with thyroid carcinoma. The most commonly reported physiologic causes of mediastinal uptake are esophageal retention of salivary secretion and uptake by hyperplastic or normal thymus gland. In this study, we evaluated physiologic cardiac blood pool (CBP) activity and its associated findings on radioiodine imaging. Cardiac blood pool activity was evaluated in 186 postablation and 32 posttherapy scans. After oral radioiodine administration, imaging was initiated on day 7. Thyroglobulin, anti-thyroglobulin and TSH blood level determination was carried out in all patients. Whole-body scans were inspected with regard to residual thyroid uptake, esophageal uptake, CBP activity, hepatic activity and metastatic iodine uptake. Uptake in the residual thyroid tissue was graded visually as mild (m), moderate (M) and significant (S). Whenever CBP activity was detected on visual inspection, its intensity was graded as mild (1), moderate (2), and significant (3). Cardiac blood pool activity was detected in 61 postablation scans (33 %). Residual thyroid uptake was observed in all patients with CBP. A significant correlation existed between the intensity of uptake and the presence of CBP (p < 0.05). The mean Tg in patients with CBP was significantly higher than those without CBP (p < 0.05). Cardiac blood pool activity was not observed in any posttherapy scans and in those scans with distant metastases in the postablation group. Linear or irregular activity pattern thought to be due to esophagus was detected in 4 % of postablation scans. The results have revealed CBP to be common on postablation scans. Its presence correlated with the intensity of residual thyroid uptake and had a significant association with increased thyroglobulin levels. Its absence on posttherapy scans despite increased Tg levels suggested that this activity is due to labeled thyroid hormones released by the residual thyroid tissue. Its presence might imply a high level of blood radiation dose.