Correlation of CT values, iodine concentration, and histological changes in the thyroid

Correlation between the thyroid computed tomography value and thyroid function in hyperthyroidism: a retrospective study

OBJECTIVE

Radioiodine (I-131) therapy for hyperthyroidism is a well-established and safe treatment option. This study aimed to investigate the relationship between the computed tomography (CT) value and the function and volume of the thyroid gland by identifying the factors that induce changes in the CT value of patients with hyperthyroidism.

METHODS

This retrospective study evaluated 38 patients with Graves' disease and 10 patients with Plummer disease. To obtain the mean CT value and volume of the thyroid gland, the entire thyroid gland was set as the region of interest. A test dose of 3.7 MBq I-131 was administered before initiating I-131 therapy, and the radioiodine uptake (RIU) rate was assessed after 3, 24, 96, and 168 h. An approximate curve was plotted based on the RIU values obtained, and the effective half-life (EHL) was calculated. The correlation between the mean CT value and the volume of the thyroid gland, 24-h RIU, EHL, and the free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), and TSH receptor antibody (TRAb) levels was evaluated.

RESULTS

The CT value exhibited a significant positive correlation with EHL in patients with Graves' disease (r = 0.62, p < 0.0001) as well as patients with Plummer disease (r = 0.74, p < 0.05). However, it did not display any correlation with the remaining parameters.

CONCLUSION

The CT value is significantly correlated with EHL, suggesting that it reflects thyroid function and is mainly related to the factors associated with iodine discharge.

Progressive loss of the thyroid tissue integrity visualised by serial CT scans

A man in his 70s developed thyrotoxicosis due to painless thyroiditis after starting nivolumab, which was subsequently followed by severe hypothyroidism. We diagnosed him as chronic thyroiditis, initiated levothyroxine supplementation and treated appropriately. Retrospective CT images of the thyroid gland during the clinical course revealed that the CT attenuation value was high at first but gradually decreased. The high-density signal of the normal thyroid tissues reflects its function of concentrating inorganic iodine, and the progressive decrease of the CT density in the present case can be viewed as a reflection of the thyroid destruction and progressive loss of iodine during the clinical course of the development of chronic thyroiditis. Considering the high incidence rate of functional thyroid disease in patients treated with immune checkpoint inhibitors, CT density of the thyroid gland needs to be paid attention to as the first sign of thyroiditis in this patient population.

Iodine concentration and content measured by dual-source computed tomography are correlated to thyroid hormone levels in euthyroid patients: a cross-sectional study in China

Background

The aim of this study was to investigate the correlation of the dual energy CT measured iodine concentration and total iodine content with blood measured thyroid parameters.

Methods

Forty-three patients with normal thyroid function at our hospital from August 2017 to October 2019 were included in this retrospective study. Dual energy CT was used to scan the neck of thyroid patients. The mean iodine concentration and thyroid tissue volume were measured to calculate the total iodine content of the thyroid. Relevant tests of triiodothyronine (FT3), total triiodothyronine (TT3), total thyroxine (TT4), free thyroxine (FT4), and thyroid hormone (TSH) were conducted. The correlation of the thyroid mean iodine concentration and total iodine content with blood-measured thyroid function was analysed.

Result

The total iodine content in the thyroid was positively correlated with FT3 but negatively correlated with TSH. The mean iodine concentration of the thyroid was positively correlated with both FT3 and TT3.

Conclusion

The thyroid iodine content measured by dual energy CT can be used to determine the human iodine nutritional status and evaluate thyroid function, which will facilitate the diagnosis and treatment of thyroid diseases.

Ectopic thyroids have lower computed tomography attenuation values than orthotopic thyroids

PURPOSE

To determine whether ectopic thyroid had the same computed tomography (CT) value as orthotopic thyroid.

METHODS

Twenty-one patients with 23 ectopic thyroids and 23 controls with orthotopic thyroids underwent CT scans and were included in this retrospective study. The CT images were reviewed in a blinded fashion by two radiologists. Independent-Samples T-test was used for comparison of CT attenuation values between two groups.

RESULTS

Ectopic thyroids had significantly lower non-enhanced attenuation (91.04 ± 5.97 Hounsfield Units vs. 106.56 ± 4.06 Hounsfield Units, P = 0.038) and contrast-enhanced attenuation (141.32 ± 6.42 Hounsfield Units vs. 169.82 ± 4.30 Hounsfield Units, P = 0.001) values than orthotopic thyroids.

CONCLUSIONS

Ectopic thyroids have lower CT attenuation values than orthotopic thyroids probably due to the structural or functional abnormalities. The dysgenesis and pathological changes of the ectopic thyroids may contribute to functional deficiency which finally leads to decrease of the CT attenuation values.

"White Thyroid" on Unenhanced Computed Tomography in Amiodarone-Induced Thyrotoxicosis Type 2

Amiodarone-induced thyrotoxicosis is a common complication of long-term amiodarone treatment. In a patient with amiodarone-induced lung toxicity and amiodarone-induced thyrotoxicosis type 2 (AIT2), a "white thyroid" was incidentally observed on an unenhanced chest computed tomography (CT) scan. This "white thyroid" resembled a thyroid image on a contrast-enhanced CT scan. Therefore, the thyroid density was prospectively evaluated on unenhanced CT scans in cases of AIT2, in euthyroid patients on amiodarone (AEuth), and in unexposed controls. The aim was to test the hypothesis of a higher thyroid density in AIT2 compared to AEuth. The thyroid density, as measured in Hounsfield Units on unenhanced CT scans, is higher in AIT2 compared to AEuth and much higher than in controls. The causality of this association and its potential diagnostic use require further study.

Diagnosis of Grave's disease with pulmonary hypertension on chest CT

OBJECTIVE

To evaluate the diagnostic accuracy of chest CT findings to diagnose Grave's disease in pulmonary hypertension.

METHODS

We retrospectively evaluated chest CT and the medical records of 13 patients with Grave's disease with (n=6) or without pulmonary hypertension (n=7) and in 17 control patients.

RESULTS

Presence of iso-attenuation of diffusely enlarged thyroid glands compared with adjacent neck muscle on non-enhanced CT as a diagnostic clue of Grave's disease, and assessment of pulmonary hypertension on CT has high diagnostic accuracy.

CONCLUSION

Chest CT has the potential to diagnose Grave's disease with pulmonary hypertension in the absence of other information.

Identification of benign and malignant thyroid nodules by in vivo iodine concentration measurement using single-source dual energy CT: A retrospective diagnostic accuracy study

This study proposed to determine whether in vivo iodine concentration measurement by single-source dual energy (SSDE) CT can improve differentiation between benign and malignant thyroid nodules. In total, 53 patients presenting with thyroid nodules underwent SSDE CT scanning. Iodine concentrations were measured for each nodule and normal thyroid tissue using the GSI-viewer image analysis software. A total of 26 thyroid nodules were malignant in 26 patients and confirmed by surgery; 33 nodules from 27 patients were benign, with 10 confirmed by surgery and others after follow-up. Iodine concentrations with plain CT were significantly lower in malignant than benign nodules (0.47 ± 0.20 vs 1.17 ± 0.38 mg/mL, P = 0.00). Receiver operating characteristic (ROC) curve showed an area under the curve (AUC) of 0.93; with a cutoff of 0.67, iodine concentration showed 92.3% sensitivity and 88.5% specificity in diagnosing malignancy. Iodine concentration obtained by enhanced and plain CT were significantly higher in malignant than benign nodules (9.05 ± 3.35 vs 3.46 ± 2.24 mg/mL, P = 0.00). ROC curve analysis showed an AUC of 0.93; with a cutoff value of 3.37, iodine concentration displayed 78% sensitivity, 95% specificity in diagnosing malignancy. Combining unenhanced with enhanced iodine concentrations, the diagnostic equation was: Y = -8.641 × unenhanced iodine concentration + 0.663 × iodine concentration. ROC curve showed an AUC of 0.98 (95% CI, 0.94, 1.00). With Y ≥ -2 considered malignancy, diagnostic sensitivity and specificity were 96%, 96.3%, respectively. This study concluded that SSDE CT can detect the differences in iodine uptake and blood supply between benign and malignant thyroid lesions.

Usefulness of SPECT/CT in Parathyroid Lesion Detection in Patients with Thyroid Parenchymal 99mTc-Sestamibi Retention

PURPOSE

Parathyroid adenoma detection with dual-phase ^99mTc-sestamibi (MIBI) scintigraphy depends on differential MIBI washout from thyroid. However, autoimmune thyroid disease (AITD) may cause MIBI to be retained in the thyroid gland and reduce parathyroid detection. We evaluated the impact of AITD on MIBI thyroid retention and additional benefit of SPECT/CT in these patients.

METHODS

Dual phase planar MIBI and SPECT/CT was performed on 82 patients. SPECT/CT was performed immediately after delayed planar scan. Thyroid density (Hounsfield unit, CT-HU) and size were measured on CT component of SPECT/CT. MIBI uptake in early scans and retention in delayed scans were visually graded and correlated with clinical factors and CT findings. Finally, planar and SPECT/CT findings were compared for parathyroid lesion visualization according to thyroid MIBI retention.

RESULTS

In early scan, multivariate analysis showed only thyroid size predicted early uptake. In delayed scan, multivariate analysis showed higher visual grade in early scan, lower CT-HU or AITD were significant predictors for delayed thyroid parenchymal retention. Overall, ten more parathyroid lesions were visualized on SPECT/CT compared to planar scans (57 vs. 47, p = 0.002). SPECT/CT was especially more useful in patients with thyroidal MIBI retention, as eight out of the ten additional lesions detected were found in patients with thyroid MIBI retention.

CONCLUSION

AITD is an important factor for MIBI thyroid parenchymal retention on delayed scans, and may impede parathyroid lesion detection. Patients with MIBI retention in the thyroid parenchyma on delayed scans are likely to benefit from an additional SPECT/CT.

CT imaging of ovarian yolk sac tumor with emphasis on differential diagnosis

Ovarian yolk sac tumors (YSTs) are rare neoplasms. No radiological study has been done to compare the imaging findings between this type of tumor and other ovarian tumors. Here we analyzed the CT findings of 11 pathologically proven ovarian YSTs and compared their imaging findings with 18 other types of ovarian tumors in the same age range. Patient age, tumor size, tumor shape, ascites and metastasis of two groups did not differ significantly (P > 0.05). A mixed solid-cystic nature, intratumoral hemorrhage, marked enhancement and dilated intratumoral vessel of two groups differed significantly (P < 0.05). The area under the ROC curve of four significant CT features was 0.679, 0.707, 0.705, and 1.000, respectively. Multivariate logistic regression analysis identified two independent signs of YST: intratumoral hemorrhage and marked enhancement. Our results show that certain suggestive CT signs that may be valuable for improving the accuracy of imaging diagnosis of YST and may be helpful in distinguishing YST from other ovarian tumors.

Ras/PKA signal transduction pathway participates in the regulation of Saccharomyces cerevisiae cell apoptosis in an acidic environment

The acidification of the medium is observed during yeast cell growth. This process contributes to the emission of organic acids, mainly acetic acid. Acetic acid is known as the inducer of apoptosis in the yeast Saccharomyces cerevisiae. In this study, we showed that hydrochloric acid can also induce apoptosis in yeast cells, and the apoptotic phenotype triggered by treating yeast cells with hydrochloric acid is modulated by the Ras/PKA pathway. The Ras/PKA pathway is highly conserved between all eukaryotic organisms, as well as cell processes that are related to apoptosis and aging. In this research, we demonstrated that the activation of the Ras/PKA pathway by insertion of Ras2(Val19) allele or deletion of PDE2 gene increases cell death, displaying the markers of apoptosis in an acidic environment. Downregulation of the pathway by deletion of RAS2, RAS1, PDE1, and insertion of the Ha-ras gene increases the cell viability and diminishes cell death with the apoptotic phenotypes. The deletion of PDE1 gene and double deletion of both phosphodiesterase genes prevent the induction of apoptosis in the cells. Modulations in the Ras/PKA pathway affect cell viability and apoptosis during natural gradual acidification of the medium as well as in acid stress conditions.

Struma ovarii: CT findings

BACKGROUND

The purpose of this study was to evaluate computed tomographic findings of struma ovarii.

METHODS

Computed tomography (CT) scans of 13 pathologically proven struma ovarii were retrospectively reviewed by two radiologists in consensus. Scans were evaluated for the laterality, size, mass configuration, margins, internal architecture, presence of intracystic high attenuation lesions on precontrast scans, and cyst wall enhancement.

RESULTS

The mean size of the tumors was 11.4 cm (range 4.7-21.0 cm). Mainly cystic (n = 8, 61.5%) or cystic (n = 5, 38.5%) appearance was common to all the tumors. All tumors were unilateral and had smooth margins. The most common internal architecture in the tumors was multicystic architecture (n = 11, 84.6%). Eleven tumors (84.6%) showed a high attenuation lesion in the cyst portion of the mass on precontrast scans and the attenuation ranged from 92.2 to 120.5 Hounsfield units (HU) (mean, 106.8 +/- 8.8 HU). The cyst wall showed no (n = 7, 53.8%), moderate (n = 5, 38.5%), or marked (n = 1, 7.7%) enhancement after administration of contrast medium.

CONCLUSIONS

On CT scans, struma ovarii appeared most often as a smooth marginated multicystic mass with a high attenuation lesion on precontrast scans and no or moderate cyst wall enhancement.

Use of helical computed tomography for measurement of thyroid glands in clinically normal cats

OBJECTIVE

To determine the dimensions and volume of thyroid tissue in clinically normal cats by use of computed tomography.

ANIMALS

8 cats.

PROCEDURE

Helical computed tomography images (2-mm collimation) were acquired from the cranial aspect of the second cervical vertebra through the caudal aspect of the fourth cervical vertebra. Data were acquired before contrast medium administration (n = 7 cats) and immediately after contrast medium enhancement (1 cat). Length, width, and height measurements of each thyroid lobe were made by use of transverse, dorsal, and sagittal plane images. Thyroid lobe volume was estimated by use of 3 methods.

RESULTS

All thyroid lobes were histologically normal. Mean dimensions for a thyroid lobe were 16.5 x 2.00 x 4.31 mm (length x width x height) using only data from transverse images. Mean thyroid lobar volume was 113.75 mm(3) using the sum of areas method. Mean total volume of thyroid tissue was 215.25 mm(3) using the sum of areas method.

CONCLUSIONS AND CLINICAL RELEVANCE

Results may be useful for computed tomography evaluation of abnormal thyroid glands in cats, which warrants investigation.

Normal cross-sectional dimensions of the thyroid gland on routine chest CT scans

PURPOSE

The purpose of this work was to determine the range of normal measurements for the thyroid gland on chest CT scans and relate it to the dimensions of the trachea.

METHOD

Chest CT scans in 118 patients were examined prospectively for visibility of the thyroid gland and its relationship to the trachea. The greatest transverse dimensions of the lobes and the transverse tracheal diameter were measured. A thyroid/trachea ratio was determined.

RESULTS

The mean value for the transverse diameter of the thyroid gland was 28.79 mm (SD 6.57 mm). The right lobe averaged 15.05 mm (SD 3.51 mm). The left lobe averaged 13.74 mm (SD 3.91 mm). Measurements for the trachea showed a mean value of 19.97 mm (SD 2.37 mm). A thyroid/trachea index was calculated with a mean value of 1.46 (SD 0.39).

CONCLUSION

Our investigation provides initial values for assessing the thyroid gland on CT scans, defining the limits of normal and the border zones of abnormal size.