Duplex scan-derived thyroid blood flow in euthyroid and hyperthyroid patients

Determinants of target absorbed dose in radionuclide therapy

In radionuclide therapy, activity kinetics in tissues determine the absorbed doses administered and thus efficacy and side effects of treatment. The objective of this work was to derive expressions for the parameters affecting the absorbed dose to a target tissue for first-order activity kinetics. The activity uptake results from contributions from the first-pass activity flow through the target tissue preceding systemic equilibration and uptake after distribution of the administered compound in the body. The absorbed dose from uptake after equilibration is the product of the mean energy deposited per decay in the target tissue, the time integral of the plasma activity concentration, the plasma volume flow per unit target tissue mass, the probability of activity removal during passage, and the mean lifetime of activity in the target tissue. Quantitative analysis of the determinants of absorbed dose exemplarily for radioiodine therapy indicates that the high uptake often observed in Graves' disease must be associated with high tissue perfusion and removal probability and that administration of stable iodine increases mean lifetime. For therapies with long residence times of the active compound in the blood, such as radioiodine therapy, the contribution of the first-pass is small compared with uptake after equilibration. The relative first-pass contribution is higher for agents that are rapidly eliminated from the blood pool, such as radiolabelled somatostatin analogues, and may dominate after arterial application. Understanding the determining parameters in radionuclide therapy reveals dose-limiting factors and opens up opportunities to optimise and individualize therapy, potentially improving treatment success rates.

Hyperthyroidism as a Precipitant Factor for Cerebral Venous Thrombosis: A Case Report

Cerebral venous sinus thrombosis (CVT) is an uncommon yet serious condition. While CVT has many known precipitants and etiologies, hyperthyroidism as a precipitant of CVT is not well understood. This study reported a case of a 41-year-old male with a 4-year history of hyperthyroidism presented with seizure. Consequently, a diagnosis of superior sagittal sinus thrombosis was confirmed by computed tomography and magnetic resonance (MR) venograms. Extensive investigations yielded no apparent underlying cause, but laboratory findings were consistent with uncontrolled hyperthyroidism. The patient improved rapidly following anticoagulation. Follow-up MR and MRV scans 2 months after treatment revealed full recanalization of the superior sagittal sinus. This case report highlighted hyperthyroidism, as a procoagulant condition, resulting specifically in superior sagittal sinus thrombosis.

Thyroid vascularization is an important ultrasonographic parameter in untreated Graves' disease patients

Graves’ disease is characterized by two sonographic features, hypoechogenicity and increased blood flow. The aim of this study was to review retrospectively ultrasound features and biochemical data of a cohort of untreated Graves’ disease patients. We reviewed charts of 42 such patients, who were referred to our Endocrinology Unit from January 2013 to May 2018. One operator performed all the thyroid sonographic scans. Serum TSH, FT3, FT4 and TSH-receptor antibodies (TRAb) levels at the time of ultrasound examination were evaluated. Over a mean follow-up of 30.9 months, about one in three patients (38%) experienced at least one recurrence of hyperthyroidism (1.4 ± 0.6 recurrence per patient), either on or off antithyroid drugs. We found that thyroid vascularization correlated directly with thyroid volume and that larger thyroids tended to be more vascularized. We also found that greater vascularization was associated with marked hypoechogenicity, and greater FT4 and TRAb levels. Patients who experienced recurrence(s) had 1.7-fold higher levels of TRAb at onset. In conclusion, thyroid hypervascularization at onset of Graves’ disease is an important sonographic feature.

The effect of preoperative Lugol's iodine on intraoperative bleeding in patients with hyperthyroidism

AIM

To investigate the effect of preoperative Lugol's iodine on intraoperative bleeding in patients with hyperthyroidism.

MATERIAL AND METHODS

This controlled, randomized, prospective cohort was carried out on 40 patients who admitted for surgery due to hyperthyroidism. Cases were randomly assigned to receive either preoperative treatment with Lugol solution (Group 1) or no preoperative treatment with Lugol solution (Group 2). Group 3 (n = 10) consisted of healthy adults with no known history and signs of hyperthyroidism. Blood flow through the thyroid arteries of patients was measured by color flow Doppler ultrasonography. Free T3, free T4, TSH, thyroid volume and the resistance index of the four main thyroid arteries were measured in all patients.

RESULTS

There was not a significant difference between gender, preoperative serum thyroid hormone levels, or thyroid gland volumes between groups 1 and 2. The mean blood flow of the patients in Group 1 was significantly lower than values in Group 2. When age, gender, thyroid hormone, TSH, thyroid volume, blood flow, and Lugol solution treatment were included as independent variables, Lugol solution treatment (OR, 7.40; 95% CI, 1.02-58.46; p = 0.001) was found to be the only significant independent determinant of intraoperative blood loss. Lugol solution treatment resulted in a 7.40-fold decrease in the rate of intraoperative blood loss.

CONCLUSION

Preoperative Lugol solution treatment was found to be a significant independent determinant of intraoperative blood loss. Moreover, preoperative Lugol solution treatment decreased the rate of blood flow, and intraoperative blood loss during thyroidectomy.

The Sonographic Features of the Thyroid Gland After Treatment with Radioiodine Therapy in Patients with Graves' Disease

The aim of the study was to describe the typical sonographic features of the thyroid gland in patients with Graves' hyperthyroidism after radioiodine therapy (RIT). Thirty patients (21 female and 9 male) with a mean age of 53 y (standard deviation [SD] ± 11.3) and with previous Graves' disease who had been successfully treated with RIT were enrolled in the study. All were hypothyroid or euthyroid after treatment. The thyroid ultrasound was carried out by a single experienced operator with an 8-MHz linear transducer. Volume, vascularity, echogenicity and echotexture of the glands were noted. The presence of nodules and lymph nodes was also documented. The mean volumes of the right lobe were 2.4 mL ± 2.9 SD (0.6-14) and the left lobe were 1.8 mL ± 1.9 SD (0.4-9.1), with a mean total volume of 4.2 mL ± 4.7 SD (1.3-19.1). Of those who had a pre-treatment ultrasound (23%), the percentage reduction in volume was 87% (p < 0.05); 93% of the glands were hypovascular, with the remaining 7% showing normal vascularity. The glands were hyperechoic and of coarse echotexture. Overall, the sonographic features of the post-RIT gland included a significantly reduced mean total volume of 4.2 mL, hypovascularity, coarse echotexture and hyperechogenicity.

Quantitative analysis of dynamic power Doppler sonograms for patients with thyroid nodules

To clarify and determine whether power Doppler sonograms are useful for the detection of malignant thyroid nodules, a computerized quantification method was used to evaluate the vascular density of a thyroid nodule in a prospective setting. Sonographic power Doppler images were collected in consecutive frames (45 frames of images), and a proprietary program (AmCAD-UV) was implemented using methods proposed in this article automatically calculated a quantified power Doppler vascular index (PDVI). The minimum PDVI value (PDVImin) was suggested as a measure of the vascular density of the nodule. The vascular densities of the peripheral and central areas of the nodule, referred to as central PDVImin and Ring PDVImin, respectively, were also evaluated. For 238 tumors (79 malignant and 159 benign) from 208 patients, all of the proposed indices of benign lesions were significantly higher than those of the malignant lesions. The area under the receiver operating characteristic curve (AUC) reaches 71% with the PDVImin. When the vascular patterns were further classified into intra-nodular and peripheral vascularity types, no vascularity type was observed significantly more frequently in malignant nodules than in benign nodules. These proposed computerized vascular indices provide a quantification method to objectively evaluate thyroid nodules and have potential as predictors of thyroid malignancy. The conventional vascular characterizations of malign nodules, that is, more vessels are observed in malignant nodules than in benign nodules, are shown to be unreliable in our study. Instead, a higher value of the quantified power Doppler vascular density was observed in benign nodules.

The role of hyperthyroidism as the predisposing factor for superior sagittal sinus thrombosis

Superior sagittal sinus thrombosis (SSST) is an uncommon cause of stroke, whose symptoms and clinical course are highly variable. It is frequently associated with a variety of hypercoagulable states. Coagulation abnormalities are commonly seen in patients with hyperthyroidism. To the best of our knowledge, there are few reports on the association between hyperthyroidism and cerebral venous thrombosis. We report on a 31-year-old male patient with a six-year history of hyperthyroidism who developed seizure and mental deterioration. Findings on brain computed tomography (CT) showed multiple hemorrhages in the subcortical area of both middle frontal gyrus and cerebral digital subtraction angiography (DSA) showed irregular intra-luminal filling defects of the superior sagittal sinus. These findings were consistent with hemorrhagic transformation of SSST. Findings on clinical laboratory tests were consistent with hyperthyroidism. In addition, our patient also showed high activity of factors IX and XI. The patient received treatment with oral anticoagulant and prophylthiouracil. His symptoms showed complete improvement. A follow-up cerebral angiography four weeks after treatment showed a recanalization of the SSS. In conclusion, findings of our case indicate that hypercoagulability may contribute to development of SSST in a patient with hyperthyroidism.

Superior thyroid artery mean peak systolic velocity for the diagnosis of thyrotoxicosis in Japanese patients

Thyrotoxicosis with diffuse thyroid disease can be caused by Graves' disease (GD) or destructive thyroiditis (DT). Optimal treatment of the underlying condition requires a prompt and accurate method for the diagnosis of thyrotoxicosis. This study evaluated measurement of the mean peak systolic velocity of the superior thyroid artery (STA-PSV) by ultrasonography in detecting thyrotoxicosis in Japanese patients. We recruited 44 patients with untreated GD, 13 with DT, 55 with treated GD, and 49 subjects without thyroid disease. Blood samples were taken to analyze thyroid function and STA-PSV was measured by ultrasonography. The mean STA-PSV was the highest in the untreated GD group, followed by treated GD patients and then those with DT. Receiver operating characteristic curves of the STA-PSV values demonstrated that the area under the curve required discriminating untreated GD from DT was 0.941. The optimal sensitivity and specificity were 83.7% and 92.3%, respectively, using 45 cm/sec as the cutoff value. In conclusion measurement of STA-PSV by ultrasonography is useful for the diagnosis of thyrotoxicosis in Japanese patients.

Reference values for Doppler ultrasound parameters of the thyroid in a healthy iodine-non-deficient population

The aim of this study was to describe normal Doppler parameter values in the thyroid arteries in an iodine-replete region. 165 individuals were randomly selected in a community located in the south-east of Brazil. We obtained a clinical history on each subject and determined serum thyrotropin, antiperoxidase antibodies, thyrotropin receptor antibody (TRAb) and thyroid volumes through ultrasound. Subjects with thyroid disease and those under 20 years of age were excluded. 84 representative subjects (30 men and 54 women) remained. The systolic peak velocity (SPV), resistive index (RI) and pulsatility index (PI) in the superior and inferior thyroid arteries were measured using a 5-12 MHz linear probe. Except for the RI, the distribution of all Doppler parameters was non-gaussian. The median and mean references for the SPV, RI and PI were 24.80 cm s(-1) and 25.85 cm s(-1), 0.60 and 0.62, and 0.98 and 1.04, respectively, for superior thyroid arteries; these reference values for the inferior thyroid artery were 20.92 cm s(-1) and 21.50 cm s(-1), 0.57 and 0.57, and 0.84 and 0.88, respectively (p<0.001). Women had greater SPV values (p<0.01). We have determined reference thyroid Doppler parameter values in our iodine-non-deficient population and prepared tables by sex and age.

Color flow Doppler sonography for the etiologic diagnosis of hyperthyroidism

Color flow Doppler sonography (CFDS) is gaining importance for the functional evaluation of the thyroid disorders. We aimed to determine the value of CFDS for the etiological diagnosis of hyperthyroidism. Fifty-five patients with hyperthyroidism (29 Graves' disease [GD] and 26 toxic adenoma [TA]), 24 patients with Hashimoto's thyroiditis (HT), and 39 euthyroid controls were included. Etiological diagnoses were carried out using standard methods. Conventional gray scale sonography was performed, followed by CFDS. Doppler patterns of the glands were scored and peak systolic velocity (PSV) measurements were obtained from intrathyroidal, perithyroidal, and perinodular vasculature. Vascular patterns were significantly more prominent, and the mean PSV values were significantly higher in the GD patients compared to the HT patients ( p < 0.001) and controls ( p < 0.001). Perinodular and intranodular signals and the mean perinodular PSV values were significantly higher in TAs compared to controls. CFDS could differentiate the untreated GD from the HT, which had similar gray scale findings. Hot nodules could also be differentiated from cold nodules with more prominent vascular patterns and significantly higher PSV values. As an inexpensive, fast, and noninvasive imaging procedure, CFDS could be helpful in the initial clinical evaluation and may avoid scintigraphy in a substantial number of thyrotoxic patients.

Variability of thyroid blood flow Doppler parameters in healthy women

The purpose of this study was to estimate variability of flow Doppler parameters in the superior thyroid artery (STHA) during the menstrual cycle in young women and to explore the influence of endogenous 17-b-estradiol (E2) and progesterone (PRG) on the velocity waveform. The plasma concentration of these hormones was correlated with flow velocities, pulsatility index (PUI), resistance index (RI) and acceleration index (accI) and time (accT), which were measured with color-coded duplex sonography 8 times during the cycle in 14 healthy women (age range: 23 to 25 years). Coefficient of variation (CV), interclass correlation (ICC), repeatability (repC) and pooled Pearson correlation (r) coefficients were used to estimate the variability of the parameters. The highest variability was found for accI and accT: CV = 48% and 31%; ICC = 0.51 and 0.45; repC = 2.8 and 95; r = 0.37 and 0.4, respectively. The CV for flow velocities varied from 25% to 26%, ICC from 0.53 to 0.56, repC from 8 to 17 and r has a value of 0.46. The respective values for RI and PUI were: 11%, 18%; 0.48, 0.55; 0.15, 0.48; and 0.46, 0.48. The diastolic blood pressure decreased significantly by 7 mmHg (p < 0.01) in the luteal phase, whereas other physiological variables were stable during the cycle. Although the fluctuations of the flow parameters during the cycle were not statistically significant, a weak linear correlation between flow velocities and concentration of E2 was found; for mean velocity r = 0.16, p < 0.05. Impedance indices showed an increasing trend in the luteal phase, along with increase of the pulse pressure index (PPI). The results showed that variability of the flow parameters in the STHA is substantial and that higher flow velocities are associated with increase of plasma concentration of 17-b-estradiol during the menstrual cycle in young women.

Estimation of antithyroid drug dose in Graves' disease: value of quantification of thyroid blood flow with color duplex sonography

The purpose of this study was to evaluate if there is an association between the antithyroid drug dose that is needed to establish euthyroidism and thyroid blood flow measurements. A total of 23 Graves' disease patients with euthyroidism taking antithyroid drug therapy were enlisted to undergo spectral duplex sonography of the thyroid arteries and color-flow mapping of the thyroid gland. Color pixel density (CPD) was calculated with computer assistance from the color-flow maps. There was a strong correlation between the CPD and methimazole dose (rp = 0.79). Methimazole maintenance dosage could be predicted from CPD values with a coefficient of determination of 0.62. In conclusion, CPD measurements could be a useful tool for the clinical endocrinologist to estimate the antithyroid drug dose that is needed to maintain euthyroidism.

Doppler evaluation of intrathyroid arterial resistances during preoperative treatment with Lugol's iodide solution in patients with diffuse toxic goiter

BACKGROUND

The aim of this study was to ascertain the utility of echo-Doppler in the analysis of the low resistance thyroid vascularization in diffuse toxic goiter (DTG), and the effectiveness of Lugol's solution (iodine-iodide solution) in patients undergoing thyroidectomy.

STUDY DESIGN

Twenty-five patients with diffuse toxic goiter were evaluated and compared with 19 normal subjects. Patients were treated with increasing doses of Lugol's solution 2% for 7 days until a total dose of 75 mg of iodine was given. Echo-Doppler was performed on the last day of treatment, 12 hours before operation.

RESULTS

Mean basal Doppler Resistance Index (RI) of intrathyroid arterial flow was significantly lower in patients with DTG compared with normal controls (0.4718 +/- 0.0625 versus 0.55 +/- 0.05, range: 0.472 to 0.643; p = 0.008). Moreover, the RI was significantly increased in patients with DTG after Lugol's solution (+16.46 +/- 10.22%, range: -2.59 to +39.97; p< 0.0005).

CONCLUSIONS

Echo-Doppler RI allowed documenting lower arterial resistances within the thyroid gland in patients with DTG. The use of preoperative Lugol's solution therapy induces normalization of those changes for safer thyroidectomy.

Relationship of thyroid blood flow to reproductive events in normal Chinese females

The purpose of this study was to investigate the blood flow characteristics in the superior thyroid artery (STA) in normal females of prepubertal, reproductive, and postmenopausal age. The study was performed in 29 prepubertal girls, 27 females of reproductive age, and 26 postmenopausal women. The peak systolic velocity (PSV) and the pulsatility index (PI) of the STA were measured repeatedly during one menstrual cycle in females of reproductive age, and measured once in each prepubertal and postmenopausal subject. Different waveforms were observed in females of prepubertal, reproductive, and postmenopausal age. The PSV of the STA increased progressively in females from prepubertal to postmenopausal phases. The PI of the STA in all of the prepubertal girls was lower than that of adult females in different phases of the menstrual cycle. In adult females, the PI in the follicular phase was significantly higher than those in the ovulatory and luteal phases. In all of the postmenopausal women, the PI was comparable to that in older prepubertal subjects and in adult females during the ovulatory and luteal phases. The results suggest that oestrogen may affect thyroid blood flow during the normal menstrual cycle. Growth and progressive change of arterial structure are suggested to affect the thyroid blood flow in prepubertal and postmenopausal states.

Alteration of thyroid blood flow during the normal menstrual cycle in healthy Chinese women

The purpose of this study was to investigate the relationship between thyroid activity and the menstrual cycle by measuring the Doppler parameters of the superior thyroid arteries in women of reproductive age. The study was performed in 27 healthy Chinese women aged between 19 and 28 y for one menstrual cycle, and 25 age-matched healthy Chinese men for 3 weeks for comparison. In women, the peak systolic velocity increased from the follicular phase to the luteal phase, and the pulsatility index decreased from the follicular phase to the ovulatory phase and increased slightly in the luteal phase. In men, alterations in the pattern of thyroid blood flow were not observed; however, the average values of Doppler parameters during the study period in women were similar to those in men. The gender difference in the pattern of flow characteristics in the superior thyroid artery suggests effects of estrogen on thyroid function.

Thyroid vascularization by color doppler ultrasonography in Graves' disease. Changes related to different phases and to the long-term outcome of the disease

To investigate possible correlations between thyroid vascularization and activity of Graves' disease, we measured blood flow (TBF) at the inferior thyroid artery and intraparenchymal vascularization (number of vessels per square centimeter) by color Doppler ultrasonography (CDU) on Graves' patients at different phases of the disease. We studied 88 patients cross sectionally: 22 untreated; 17 euthyroid after 6 months of methimazole; 49 euthyroid at drug withdrawal after 12 to 24 months of treatment. The patients of the latter group were followed up for 29.1 +/- 6.3 months after discontinuation of treatment. On the day of CDU examination, free triiodothyronine (FT3), free thyroxine (FT4), thyrotropin (TSH), antiperoxidase and anti-TSH receptor (TRAb) antibodies were measured. Vascularization indices were significantly higher in the Graves' patients than in controls. In the patients euthyroid under treatment, vascularization was not significantly lower than in the untreated group, but TBF and vessel number both appeared clearly reduced in the patients tested at drug withdrawal. The vascularization indices at drug withdrawal were significantly higher in the patients who relapsed than in those in stable remission: TBF (mL/min) 50.6 +/- 36.8 vs. 23.8 +/- 17.5, p = 0.001; vessel number/cm2 1.8 +/- 0.8 vs. 0.8 +/- 0.5, p = 0.002. A multivariate analysis, evaluating the predictive value of vascularization, hormonal and immunological parameters for relapse, demonstrated a significant predictive value for TRAb (RR 8.2; p = 0.001) and a weak predictive value for TBF (RR 1.1; p = 0.02). In conclusion, CDU examination confirms that thyroid hypervascularization in Graves' disease is not related to thyroid hormone circulating levels. The association of increased TBF and high levels of TRAb in the relapsing forms of disease suggests that thyroid hypervascularization is probably related to the activity of the underlying autoimmune processes.

Superior sagittal sinus thrombosis and thyrotoxicosis. Possible association in two cases

BACKGROUND

Superior sagittal sinus thrombosis is an uncommon cerebrovascular accident that is frequently associated with diseases that may contribute to the development of thrombosis through hypercoagulability, stasis of the local blood stream, and abnormalities of the vessel wall. In approximately 25% of cases underlying diseases remain unrecognized.

CASE DESCRIPTIONS

Two patients with superior sagittal sinus thrombosis during a thyrotoxic phase of Graves' disease are described. Both patients presented with hemiplegia, seizures, and a large goiter.

CONCLUSIONS

The development of superior sagittal sinus thrombosis is multifactorial. Patients with thyrotoxicosis and a large goiter may be predisposed to the development of superior sagittal sinus thrombosis through hypercoagulability and stasis of the local venous blood flow.

Normalization of thyroid blood flow in Graves' hyperthyroidism following radioactive iodine therapy

In a group of 12 patients with Graves' hyperthyroidism, administration of 514 +/- 43 (mean +/- SD) MBq iodine-131 was associated with a fall of superior thyroid artery (STA) blood flow in two at 6 months and in eight at 11 months. The reduction in time-averaged velocity at 11 months correlated with the reduction in FT4 (r = 0.72, P less than 0.01) and in FT3 (r = 0.64, P less than 0.025) at this time. In four patients who had persistent elevated STA blood flow, two were still hyperthyroid. The diameter of the STA was unchanged at 6 months and only half the patients had reduction of their STA size at 11 months after radioiodine (RAI) therapy. These data indicate that normalization of STA blood flow precedes normalization of STA size in patients treated with RAI. Further work is required to determine whether STA blood flow measurements are of predictive value in treatment outcome.