Quantification of the Thyroid Scan (TS) and correlation to Multiparametric Ultrasounds (MPUS): A textbook case of nuclear molecular imaging

For decades, thyroid scintigraphy (TS) has been considered an interesting tool, especially in the field of hyperthyroidism. In recent years, TS has rapidly gained importance since it provides unique molecular information that cannot be obtained by any other modality. In fact, despite a limited 6 mm spatial resolution, it can highlight molecular and histo-functional changes that characterize most thyroid function disorders. However, to become such a powerful molecular image, the TS must be quantified. How much iodine is taken-up characterizes the Uptake (Up), while where iodine distributes characterizes the Spatial Targeting (ST). Methodology, results and limits of the thyroid Uptake are presented, including suppressed tests. Methods to determine the anatomical thyroid volume are revisited with special focus on planar scintigraphy. Recent developments in quantification make the ¹²³I-TS a new molecular imaging procedure. Since ¹²³I targets the sodium iodide symporter (NIS) and tracks the whole organification process, we derived a fundamental linear relationship between the TSH and the precocious (120–240 min) Uptake (p¹²³IUp). This relationship indicates whether the ¹²³I input follows the physiological TSH stimulation or is predictive of a non TSH-suppressible function, whatever the imaging pattern. This allows identification of toxic or compensated (TSH > 0.1 mU/L) Thyroid Functional Autonomy (TFA), even at baseline. Spatial Targeting, measured with the aid of computational algorithms, provides a reproducible Spatial Targeting Index (STI). This allows estimating a functional thyroid volume, that is likely more informative than the anatomical one. Most aspects of TS quantification and the interest to compare the structure (mostly MultiParametric US) and the function (molecular ¹²³I-TS) are presented.     

Radioiodine-131 therapy (RIT) in benign thyroid diseases: Personalized prescription based on objectives with optional use of pharmacological modulators

¹³¹I therapy (RIT) in benign thyroid diseases is the oldest and most currently used application of internal radiotherapy. With the new molecular ¹²³I-TS images one may identify 15 presentations that can benefit from RIT. With three groups of activity determination corresponding to a dozen approaching protocols, several judgmental criteria (eu-, hypo-, hyperthyroidism, relapses etc.) and varying timeframes to assess the success, a “best method of activity calculation” makes little sense. Four clinical objectives must be first identified (goal): antitoxic (euthyroidism), ablative (hypothyroidism), reductive (to reduce a targeted volume) and preventive (to prevent progression from compensated to overt hyperthyroidism) ¹³¹I-RIT. A dose response relationship as regards the target volume reduction is firmly established in the short term (1-year) and explains the clinical outcome in Thyroid Functional Autonomy (TFA). In Grave's disease (GD), other factors may interfere that make the long-term function less predictable. Pharmacological modulators of ¹³¹I-RIT such as antithyroid drugs (ATDs) and LT3 must be skillfully handled. ATDs interfere with iodine kinetics, enhance the heterogeneity of the spatial dose deposition and diminish the accuracy of absorbed dose deposition, especially when using poorly controlled dosimetric approaches. Short LT3 administration suppresses TSH that allows direct targeting of the autonomously functioning thyroid tissue. The three main groups and variants of activity calculation are presented in detail. Calculating the activity allows a 50% average reduction in the ¹³¹I administered dose. Medical strategy should favour the informed patient's choice, after excluding the rare medical causes prompting discussion of an ablative approach. In TFA, low occurrence of hypothyroidism is the rule provided the treatment be given with a TSH < 0.1 mU/L, spontaneously or after LT3 suppression (compensated variety). In GD a long-term remission is rare (< 30%) and should be thoroughly discussed since it leads to euthyroidism in approximately 50% after a 12-year follow-up. Depending on the etiology (GD/TFA) and the 4 clinical goals, ¹³¹I RIT planning is presented with optional choice of a patient adapted method of activity calculation and appropriate management of pharmacological modulators.     

Grave's disease affecting one thyroid lobe: About 2 cases

Graves’ disease is an autoimmune disorder of thyroid which is characterized by hyperthyroidism, diffuse goiter, ophthalmopathy. Due to the pathophysiological mechanism of the disease, the disease affects both thyroid lobes. Unilateral involvement of the thyroid gland in patients with Graves’ disease is a rare entity, which suggests a difference between the two thyroid lobes. Clarifying this phenomenon could be a line of research for a better understanding of the pathophysiology of Graves's disease. This entity must be known to the clinician in order to take it better and avoid misdiagnosis. Here we present two cases of Graves’ disease which had unilateral involvement of the thyroid gland and discuss the hypotheses explaining this observation.     

Unusual spread of the follicular thyroid carcinoma,metastases to liver and pancreas

We report a multimetastatic follicular thyroid carcinoma(FTC) with match lesions between ¹⁸F-FDG PET/CT and post-treatment ¹³¹I imaging. The patient had a history of thoracic vertebra corpectomy surgery and liver tru-cut biopsy; both resulted in metastases of FTC. After total thyroidectomy surgery, the patient was referred to the ¹⁸F-FDG PET/CT to investigate other possible metastatic foci. ¹⁸F-FDG PET/CT showed increased FDG uptakes on a cervical lymph node, bones, lung, liver, and pancreas. After treatment of ¹³¹I, post-treatment iodine scintigraphy demonstrated iodine uptakes in the same areas as the ¹⁸F-FDG PET/CT scan and at the thyroid bed. All the matched lesions were concluded as a spread of the FTC. Here we describe an infrequent differentiated thyroid carcinoma case with metastases to the liver and pancreas. This case report also highlights the importance of ¹⁸F-FDG PET/CT in determining the extent of thyroid cancer.     

Scintigraphy has the potential to replace thyroid stimulating hormone and ultrasonography in hyperthyroidism diagnosis

The value of thyroid scintigraphy in hyperthyroidism diagnosis has long been the subject of debate. Unresolved issue is whether scintigraphy should be performed routinely, selectively, or for all hyperthyroidism patients. So, this study is concerned with the evaluation of thyroid scintigraphy for identifying hyperthyroidism in comparison with thyroid stimulating hormone (TSH) and ultrasound. This is cross sectional study including convenient patients sample (n = 50, 15 males and 35 females) aged (20–50 years) with primary hyperthyroidism and were attending endocrine clinics at King Faisal Specialist Hospital and Research Centre. All patients performed clinical investigations (TSH, ultrasound and thyroid scintigraphy). Among these patients, 96%, 48/50, had positive findings for hyperthyroidism with thyroid SC (95% CI; 96.0–99.5%); 84%, 42/50, had positive findings for hyperthyroidism by US (95% CI; 70.9–92.8%); and 56%, 28/50, had positive findings for hyperthyroidism by TSH measurement (95% CI; 41.3.0–70.0%). There was very good agreement between scintigraphy diagnosis and ultrasonography (kappa score = 0.812 (P < 0.0001), 95% CI (0.77–0.85). In many cases, scintigraphy provides considerably more functioning and anatomic details than ultrasound. In conclusion, these findings bring forth practical aspects of thyroid scintigraphy utilization for hyperthyroidism. By combining functional and anatomical information in one step, scintigraphy provides non-invasive, simple, fast and cost effective hyperthyroidism diagnostic method and has the potential to replace TSH and ultrasonography in hyperthyroidism investigation.     

Plasmodium berghei: Thyroid hyperplasia and thyroid hyperactivity in mice

Statistically significant (P < 0.05) thyroid hyperactivity (¹³¹I% uptakes) occurs on certain days in Plasmodium berghei infected C3H mice. Male mice thyroid glands are made more hyperactive by the malaria than the female glands. Hyperactive thyroid glands may be at least one cause of hypocholesterolemia in plasmodium-infected rodents. Thyroid hyperplasia was found only in experimental mice ($\text{6}\text{20}$ males; $\text{8}\text{20}$ females). A hyperactive thyroid gland appears to be an unreported aspect of experimental acute P. berghei infections in mice. The hyperthyroidism may be due to possible toxic substances acting either directly on the thyroid gland, or indirectly on the hypothalamus affecting TSH production.     

Impact of Thyroid Function on Serum Cystatin C and Estimated Glomerular Filtration Rate: A Cross-Sectional Study

ObjectiveTo determine the relationship between thyroid-stimulating hormone (TSH) and cystatin C (CysC) and estimated glomerular filtration rate calculated by Cys^C (e^GFRCysC).MethodsWe conducted a cross-sectional study including 8,126 male participants. Serum creatinine (Cr), CysC, eGFR calculated by Cr (eGFR_Cr), and eGFR_CysC were determined and compared in euthyroid and subclinical thyroid dysfunction patients. Relationships between TSH and Cr, cystatin C, eGFR_Cr, and eGFR_CysC were assessed by linear and quadratic trend analyses. Odds ratios (ORs) of chronic kidney disease (CKD; eGFR<60 mL/min/1.73m²) were calculated according to categories of thyroid function using TSH values of 2.01-3.00 mIU/L as a reference.ResultsSerum CysC level was significantly elevated, and eGFR_CysC was significantly reduced in both sub-clinical hypothyroidism and subclinical hyperthyroidism. TSH was negatively and linearly associated with Cr and eGFR_Cr (P<.001). Quadratic trends were found between TSH and cystatin C or eGFR_CysC (P<.001). Compared with individuals with TSH of 2.01-3.00 mIU/L, the prevalence of CKD_CysC was significantly higher in subjects with TSH<0.40 mIU/L, 3.01-4.00 mIU/L, and 4.01-7.00 mIU/L, while the prevalence of CKD_Cr was only significantly higher in subjects with TSH>7.0 mIU/L.ConclusionDespite only studying male subjects and using eGFR rather than standard GFR, we conclude that thyroid function differentially affects serum CysC and Cr concentrations. Subclinical hypothyroidism and subclinical hyperthyroidism are both associated with elevated CysC, reduced eGFR_CysC, and higher prevalence of CKD_CysC. Assessment of renal function with CysC should be avoided in patients with thyroid dysfunction. (Endocr Pract. 2013;19:397-403)     

Metabolomic profile in hyperthyroid patients before and after antithyroid drug treatment: Correlation with thyroid hormone and TSH concentration

Hyperthyroidism (HT) is characterized by an intense metabolic impact which affects the lipid, carbohydrate and amino acids metabolism, with increased resting energy expenditure and thermogenesis. Metabolomics is a new comprehensive technique that allows to capture an instant metabolic picture of an organism, reflecting peculiar molecular and pathophysiological states. The aim of the present prospective study was to identify a distinct metabolomic profile in HT patients using ¹H NMR spectroscopy before and after antithyroid drug treatment. This prospective study included 15 patients (10 female, 5 male) who were newly diagnosed hyperthyroidism. A nuclear magnetic resonance (¹H NMR) based analysis was performed on plasma samples from the same patients at diagnosis (HypT₀) and when they achieved euthyroidism (HypT₁). The case groups were compared with a control group of 26 healthy volunteers (C). Multivariate statistical analysis was performed with Partial Least Squares-Discriminant Analysis (PLS-DA). PLS-DA identified a distinct metabolic profile between C and untreated hyperthyroid patients (R²X 0.638, R²Y 0.932, Q² 0.783). Interestingly, a significant difference was also found between C and euthyroid patients after treatment (R²X 0.510, R²Y 0.838, Q² 0.607), while similar cluster emerged comparing HypT₀ vs HypT₁ patients. This study shows that metabolomic profile is deeply influenced by hyperthyroidism and this alteration persists after normalization of thyrotropin (TSH) and free thyroid hormone (FT3, FT4) concentration. This suggests that TSH, FT3 and FT4 assays may not be insufficient to detect long lasting peripheral effects of the thyroid hormones action. Further studies are needed to clarify whether and to what extent the evaluation of metabolomics profile may provide relevant information in the clinical management of hyperthyroidism.     

Exploring the role of copper and selenium in the maintenance of normal thyroid function among healthy Koreans

BackgroundSelenium and iodine are trace elements well known to have important roles in the synthesis and metabolism of thyroid hormones. However, the effects of other trace elements on thyroid hormones are still inconclusive. We investigated the association between several trace elements and thyroid hormones.MethodsThe data of 448 subjects who were measured for both, trace elements and TSH/free T4, at the Heath Checkup Center were retrospectively reviewed. The presence of thyroiditis (from thyroid echogenicity) and thyroid nodules were reviewed in the subjects who underwent thyroid ultrasonography.ResultsBlood concentrations of manganese, copper, selenium, and molybdenum were associated with TSH or free T4. After adjusting for age, sex, BMI, smoking, and alcohol consumption, blood copper levels were positively associated with free T4 in both sexes and selenium levels were positively associated with free T4 in women. There was no association between trace elements and thyroiditis. Blood copper concentration had a weak non-linear association with the presence of thyroid nodules.ConclusionsThis study demonstrated that blood concentrations of copper and selenium were significantly associated with free T4 in healthy Korean subjects with sufficient iodine intake suggesting their role in maintaining normal thyroid function.     

老年2型糖尿病患者血清促甲状腺激素水平及其与冠脉病变程度的相关性分析

目的:探讨老年2型糖尿病(T2DM)患者血清促甲状腺激素(TSH)水平及其与患者冠脉病变程度的相关性。方法:回顾性分析2015年6月～2017年6月我院收治的88例老年T2DM患者(T2DM组)、50例健康体检者(对照组)的临床资料,根据血清TSH水平将T2DM组分为四个亚组,A组(0.45～1.49 m IU/L,n=18)、B组(1.50～2.49 m IU/L,n=23)、C组(2.50～3.49 m IU/L,n=22)、D组(≥4.5 m IU/L,n=25)。比较T2DM组与对照组TSH水平的差异,并根据计算机断层血管造影(CTA)结果计算Gensini评分,分析Gensini评分与血清TSH水平的相关性。结果:T2DM组血清TSH水平显著高于对照组,且随着血清TSH水平的升高,T2DM患者的年龄、TC、TG、LDL-C明显增加,而HDL-C、T3明显降低(P0.05)。C组病变支数显著多于A组,重度病变的比例明显升高,而D组病变支数、病变程度与A组、B组、C组比较差异均有统计学意义(P0.05)。血清TSH水平与Gensini评分呈显著正相关(r=0.577,P0.05)。结论:老年T2DM患者血清TSH水平显著升高,且与患者冠脉病变严重程度呈显著正相关,血清TSH水平有助于评估老年T2DM患者冠脉病变的严重程度。     

Effects of Thyroid Dysfunction and the Thyroid-Stimulating Hormone Levels on the Risk of Atrial Fibrillation: A Systematic Review and Dose-Response Meta-Analysis from Cohort Studies

ObjectiveTo explore the relationship between thyroid dysfunction, thyroid-stimulating hormone (TSH) levels, and risks of atrial fibrillation (AF) in studies and conduct a dose-response meta-analysis on the correlation between the TSH levels and risk of AF.MethodsThirteen studies from 5 databases with 649 293 subjects (mean age, 65.1 years) were included. The dose-response meta-analysis was conducted by comparing the risk ratios (RRs) and 95% confidence intervals (CIs) for incident AF associated with different levels of TSH (vs TSH level of 0 mU/L) across studies. Data were collected until October 25, 2021.ResultsSubclinical hyperthyroidism, subclinical hypothyroidism, and clinical hyperthyroidism were associated with an increased risk of AF (RR, 1.70; 95% CI, 1.11-2.62; RR, 1.23; 95% CI, 1.05-1.44; and RR, 2.35; 95% CI, 1.07-5.16, respectively), whereas clinical hypothyroidism was not associated with the significantly increased risk of AF (RR, 1.20; 95% CI, 0.72-1.99). A nonlinear relationship was observed in 2 models (crude model, P_nonlinear < .001; adjusted model, P_nonlinear = .0391) between the TSH levels and risks of AF.ConclusionsOur study indicated that subclinical hyperthyroidism, subclinical hypothyroidism, clinical hyperthyroidism were associated with the risk of AF, and the results for the TSH levels and risk of AF were mixed, which showed a U-shaped relationship.     

Characterization of the four isomers of 123I-CMICE-013: A potential SPECT myocardial perfusion imaging agent

Myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT) is widely used in the assessment of coronary artery disease (CAD). We have developed ¹²³I-CMICE-013 based on rotenone, a mitochondrial complex I (MC-1) inhibitor, as a promising new MPI agent. Our synthesis results in a mixture of four species of ¹²³I-CMICE-013 A, B, C, D. In this study, we separated the four species and evaluated their biodistribution and imaging properties. The cold analogs ¹²⁷I-CMICE-013 A, B, C, D were isolated and characterized and their chemical structures proposed. Methods: ¹²³I-CMICE-013 was synthesized by radiolabeling rotenone with Na¹²³I in trifluoroacetic acid (TFA) with iodogen as the oxidizing agent at 60 °C for 45 min, and the four species were separated by RP-HPLC. The cold analogs ¹²⁷I-CMICE-013 A, B, C and D were isolated with a similar procedure and characterized by NMR and mass spectrometry. Biodistribution and microSPECT imaging studies were carried out on normal rats. Results: We propose the mechanism of the rotenone iodination and the structures of the four species. First, I⁺ forms an intermediate three-membered ring with 6′ and 7′ carbons. Second, the lone electron pair of the water molecule attacks the 6′ or 7′-carbon, following by the formation of 6′-OH, and 7′-I bonds as in major products C and D, or 6′-I and 7′-OH bonds as in minor products A and B. The weaker 6′-I bond in the intermediate prompts the nucleophilic attachment of water at the favorable 6′-carbon to generate C and D. MicroSPECT images of ¹²³I-CMICE-013 A, B, C, D in rats showed clear visualization of myocardium and little interference from lung and liver. The imaging time activity curves and biodistribution data showed complex profiles for the four isomers, which is not expected from the structure activity relationship theory. Conclusion: ^123/127I-CMICE-013 A and B are constitutional isomers with C and D, while A and C are diastereomers of B and D, respectively. Overall, the biological characteristics of the four species are not correlated perfectly with their molecular structures.     

Centiloid scale analysis for 18F-THK5351 PET imaging in Alzheimer’s disease

PurposeA standardized method for quantification is required for analyzing PET data, but such standards have not been established for tau PET imaging. The Centiloid scale has recently been proposed as a standard method for quantifying amyloid deposition on PET imaging. Therefore, the present study aimed to apply the Centiloid scale to ¹⁸F-THK5351 PET imaging in Alzheimer’s disease (AD).MethodsWe acquired ¹⁸F-THK5351 PET, ¹¹C-PiB PET, and MR images from 47 cognitively normal (CN) individuals and 28 patients with AD with mild to moderate dementia. PET images were spatially normalized to Montreal Neurological Institute space. The PET signals were then normalized using the signal in the reference volume of interest (VOI). Target VOI for specific ¹⁸F-THK5351 retention in AD was extracted by voxel-wise comparison of PET images between the 47 CN individuals and 16 AD patients with moderate dementia. Scale anchor points were defined by the CN individuals as 0-anchor points and by that of the average of the typical AD patients as 100-anchor points.ResultsSpecific retention of ¹⁸F-THK5351 was predominant in the angular gyrus, inferior temporal cortex, and parieto-occipital regions in patients with AD. Standardized uptake value ratio (SUVR) of 1.227 and 1.797 were defined as 0- and 100-anchor points, respectively. ¹⁸F-THK5351 PET data could be expressed using the Centiloid scale, with the SUVR of the ¹⁸F-THK5351 PET images converted to Centiloid using our VOI, the standard Centiloid reference VOI, and the following equation: Centiloid = 169.0 × SUVR–204.6.ConclusionCentiloid methods can be applied to tau PET imaging using ¹⁸F-THK5351.     

桥本氏病合并甲状腺乳头状癌患者血清甲状腺相关激素水平的变化及意义

目的:探究桥本氏病(HT)合并甲状腺乳头状癌(PTC)患者血清甲状腺相关激素水平的变化及意义。方法:对我院148例HT患者的临床资料进行回顾性分析,根据其是否合并PTC分为HT合并PTC组(n=68)和单纯HT组(n=80)。比较两组患者性别、年龄及血清促甲状腺激素(TSH)、甲状腺功能指标[游离三碘甲腺原氨酸(FT3)、游离甲状腺素(FT4)]、抗甲状腺抗体[甲状腺球蛋白抗体(TGAb)、甲状腺过氧物酶抗体(TPOAb)]水平等临床资料差异,分析血清TSH水平变化及意义。结果:HT合并PTC组患者男性比例、年龄、病程及血清TSH水平均大于单纯HT组,血清TGAb、TPOAb水平则均小于单纯HT组(P0.05);血清FT3、FT4水平比较差异无统计学意义(P0.05)。HT合并PTC患者组血清TSH4.2 m IU/L患者占比高于血清TSH正常组(P0.05)。血清TSH4.2 m IU/L患者中HT合并PTC患者的占比大于血清TSH水平正常的患者(P0.05)。HT合并PTC患者中,血清TSH水平4.2 m IU/L患者中央区淋巴结转移发生率高于血清TSH水平正常患者(P0.05);血清TSH4.2 m IU/L与血清TSH正常患者多灶癌发生率比较差异无统计学意义(P0.05)。结论:HT患者血清TSH水平升高可能促进其甲状腺组织癌变,HT合并PTC患者血清TSH水平升高可能促进其中央区淋巴结转移。     

A longitudinal follow-up study of the quantification of dopamine transporters with 123I-Ioflupane (DaTscan)

IntroductionThe aim of this study was to test a quantification tool to measure the evolution of the functional reserve of dopaminergic transporters, from two consecutive ¹²³I-Ioflupane Datscan.MethodsImages of 58 patients who underwent two consecutive ¹²³I-Ioflupane examinations (DaTscan^®) in the Nuclear Medicine Department of Toulouse University Hospital from 2002 to 2016 were analysed in this retrospective study. Twenty-four patients had a normal dopaminergic neuronal operation (N group), 34 had a pathological impairment of the dopamine transporters (P group) which 15 did not receive any treatment (PO group) and 16 who received treatment (P1 group). The DaTscan^® image quantification was performed with the DaTsofr3D^® software, permitting to measure the right and left binding potential (PL) of the caudate nucleus (NC), putamen (PU) and striatum (ST).ResultsIn the N group, the annual mean change of the binding potential (NC, PU, ST) was respectively (−0.03%/year, −0.96%/year, −0.43%/year) and did not significantly differ from the normal physiological decline of −0.66%/year. The annual binding potential mean changes of the P group (−9.6%/year, −13%/year, −11%/year) significantly differed not only from the N group but also from the physiological decline. No significant difference was shown between P0 and P1 groups.ConclusionThe DaTsoft3D^® quantification software permits to split up two groups according to the evolution of the dopamine transporter density with a significant difference in the binding potential mean annual rate.     

Performance de la 18FDG-TEP dans le dépistage de paragangliome chez des patients porteurs d’une mutation SDHx

ObjectiveTo evaluate the performance of ¹⁸FDG-PET/CT for detecting infra-clinic paraganglioma (PGL) in SDHx mutation carriers (relatives).Patients and methodsSixty-six patients, from 13 distinct families underwent a genetic testing on the SHD genes between 2003 and 2012. Among the 45 patients with a mutation, 30 with a ¹⁸FDG-PET performed at initial work-up were included in this retrospective study. A gadolinium-enhanced magnetic resonance angiography of the neck (angio-MR) was performed in all cases, a thoracoabdominal-pelvic contrast-enhanced computed tomography (TAP-CT) in 25 cases, a TAP-MR in 20 cases, a ¹²³I-metaiodo-benzylguanidine scintigraphy (¹²³I-MIBG) in 20 cases and a somatostatin receptor scintigraphy (SRS) in 20 cases. Gold standard was histologic or composite (confirmation by another imaging method and follow-up).ResultsA tumor was found in five subjects: 2 abdominal PGL, 1 pheochromocytoma and 2 PGL of the neck. The sensitivity of ¹⁸FDG-PET was 100 %, of SRS was 80 %, of ¹²³I-MIBG was 60 % and of anatomical imaging (association between angio-MR of the neck and TAP-CT and/or TAP-MR) was 100 %. Three false positive lesions were described: 2 with the ¹⁸FDG-PET imaging and 1 with the TAP-MR technique.Conclusion¹⁸FDG-PET/CT is an excellent tool for screening SDHx relatives and should be completed by an angio-MR of the neck if suspicion of abnormality. Association of angio-MR of the neck and TAP-MR has the advantage of being a non-irradiating imaging method but with limited access in some countries.     

Nature of the phosphorylated 26 000 molecular weight protein extracted from dog thyroid with contractile proteins

Dog thyroid contractile proteins are characterized by their ATPase activity at high KCl concentration. In the presence fo Ca²⁺, 80 nmol ATP are hydrolyzed per min per mg protein. This Ca²⁺-ATPase activity is inhibited by Mg²⁺ but not influenced by sodium azide.The 26 000 molecular weight protein which is present in thyroid contractile protein preparations and the phosphorylation of which is stimulated by thyroid stimulating hormone (TSH) is suggested to be identical to the lysine-rich histones (H₁). Indeed, radioactive thyroid H₁ histones added to unlabelled thyroid slices copurify with the contractile proteins and migrate at the same level as the 26 000 molecular weight protein when submitted to electrophoresis in polyacrylamide sodium dodecyl sulfate gels of different acrylamide concentrations.     

The value of 99mTc-MIBI scan in the detection of malignancy potential of hypermetabolic thyroid incidentalomas of 18F-FDG PET/CT

Aim of the studyIncreasingly use of PET/CT leads to discovery of incidental findings. Hypermetabolic thyroid nodules are one of the unexpected lesions in PET/CT imaging with an increased risk of thyroid cancers. Our study aims to determine the malignant potential of incidentally detected 18F-FDG avid thyroid nodules by using Tc-99m MIBI imaging.Materials and methodsPET/CT scans were performed for nonthyroidal purposes and were evaluated for the presence of hypermetabolic thyroid nodules. Tc-99m MIBI scans and ultrasonography-guided fine needle aspiration biopsies were subsequently performed for all patients.ResultsPrimary thyroid malignancies were identified in 25% of patients with increased focal FDG uptake at definitive diagnosis. Among the patients with FDG avid thyroid nodules, Tc-99m MIBI scan showed true-positive results in all thyroid carcinomas (n:7) with a 36.3% (4/11) false-positivity rate. In three patients with indeterminate cytology results, Tc-99m MIBI scan findings were also negative. The sensitivity, specificity, positive predictive value of Tc-99m MIBI scan in predicting the malignancy of FDG-positive thyroid nodules were 100%, 77%, 63.6%, respectively.ConclusionThe implementation of ^99mTc-MIBI scan performed by dual phase and SPECT/CT modality might be a helpful cost-effective approach in addition to FNAB in patients with ¹⁸F-FDG-positive thyroid nodules and indeterminate cytology to improve the patients’ prognosis and reduce unnecessary thyroid operations with associated use of FNAB.