The impact of 99mTc-DTPA orbital SPECT in patient selection for external radiation therapy in Graves' ophthalmopathy

Thyroid Accumulation of 99m Tc-DTPA in Graves Disease

ABSTRACT

99m Tc-DTPA dynamic renal scintigraphy for evaluating glomerular filtration rate was performed in a 29-year-old woman with hyperuricemia and Graves disease. Subsequently, 99m Tc-DTPA orbital scintigraphy was conducted to determine the activity of Graves ophthalmopathy. Thyroid accumulation of 99m Tc-DTPA was incidentally identified. This should be cautiously distinguished from 99m Tc-pertechnetate uptake, considering that the salivary glands, oral cavity, and stomach were not visualized. Our case demonstrates that augmentation of blood supply, enhancement of capillary permeability, and accumulation of inflammatory exudate may be involved in the pathological process of Graves disease.

Deep learning-based diagnosis of disease activity in patients with Graves' orbitopathy using orbital SPECT/CT

PURPOSE

Orbital [99mTc]TcDTPA orbital single-photon emission computed tomography (SPECT)/CT is an important method for assessing inflammatory activity in patients with Graves' orbitopathy (GO). However, interpreting the results requires substantial physician workload. We aim to propose an automated method called GO-Net to detect inflammatory activity in patients with GO.

MATERIALS AND METHODS

GO-Net had two stages: (1) a semantic V-Net segmentation network (SV-Net) that extracts extraocular muscles (EOMs) in orbital CT images and (2) a convolutional neural network (CNN) that uses SPECT/CT images and the segmentation results to classify inflammatory activity. A total of 956 eyes from 478 patients with GO (active: 475; inactive: 481) at Xiangya Hospital of Central South University were investigated. For the segmentation task, five-fold cross-validation with 194 eyes was used for training and internal validation. For the classification task, 80% of the eye data were used for training and internal fivefold cross-validation, and the remaining 20% of the eye data were used for testing. The EOM regions of interest (ROIs) were manually drawn by two readers and reviewed by an experienced physician as ground truth for segmentation GO activity was diagnosed according to clinical activity scores (CASs) and the SPECT/CT images. Furthermore, results are interpreted and visualized using gradient-weighted class activation mapping (Grad-CAM).

RESULTS

The GO-Net model combining CT, SPECT, and EOM masks achieved a sensitivity of 84.63%, a specificity of 83.87%, and an area under the receiver operating curve (AUC) of 0.89 (p < 0.01) on the test set for distinguishing active and inactive GO. Compared with the CT-only model, the GO-Net model showed superior diagnostic performance. Moreover, Grad-CAM demonstrated that the GO-Net model placed focus on the GO-active regions. For EOM segmentation, our segmentation model achieved a mean intersection over union (IOU) of 0.82.

CONCLUSION

The proposed Go-Net model accurately detected GO activity and has great potential in the diagnosis of GO.

Current imaging methods for assessing Graves` orbitopathy activity with particular emphasis on FDG-PET

The most frequent extrathyroidal Graves' disease manifestation is Graves' orbitopathy (GO). The treatment of GO is determined by its severity and activity. There is currently no reliable, impartial method for assessing it clinically or distinguishing fibrosis from active inflammatory disorders. Today, imaging methods including orbital ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) are frequently employed to show pathological abnormalities in the ocular adnexa of GO patients. In addition, a not widely accepted technique - 99mTc-DTPA SPECT - has some potential to evaluate retrobulbar inflammation in GO patients. However, FDG-PET/CT is possibly superior to other imaging modalities in detecting inflammation in GO and it may be useful in assessing disease activity in case of clinical or serological uncertainty. It might also act as an early indicator of GO development and its aggravation before irreversible tissue alterations take place and may be used in the differential diagnosis of inflammatory disorders of the orbit. However, before FDG-PET/CT could be applied in daily clinical practice, the methodology of GO activity assessment with defined cut-off values for radionuclide concentration - standardized units of value (SUV) have to be established and validated. In addition, the limitations of this technique have to be recognized.

Monitoring and Predicting Treatment Response of Extraocular Muscles in Grave's Orbitopathy by 99mTc-DTPA SPECT/CT

Objective: To investigate single-photon emission computed tomography/computed tomography (SPECT/CT) for assessing inflammation in the extraocular muscles (EOMs) and predicting the therapeutic efficacy of periocular glucocorticoid therapy (PGT) for Grave's ophthalmopathy (GO).

Materials and Methods: A total of 412 eyes from 206 patients with GO referred for ^99mTc-DTPA orbital SPECT/CT were enrolled. Fourteen age- and gender-matched healthy controls (28 eyes) were included. The thickness and uptake ratio (UR) of four EOMs were derived from SPECT/CT. Eighty-six eyes from patients with GO patients received PGT. Changes in SPECT/CT parameters were evaluated between the pre- and post-treatment.

Results: 195 eyes and 217 eyes were classified as active and inactive stages by clinical activity score (CAS). Values of the thickness and UR of each EOM, T_max, and U_max were all significantly higher in the active GO than in the inactive GO and controls (p < 0.01). Among the 86 eyes (48 GO patients) included in the efficacy analysis, 56 eyes and 30 eyes were classified as responders and non-responders. Values of thicknesses and UR of each EOM, the maximum thickness (T_max), and the maximum UR (U_max) all dropped following PGT in the responders (p < 0.01). Logistic regression analysis identified the U_max as an independent predictor for the responders (p < 0.01). Moreover, the U_max demonstrated incremental predictive value over clinical characters and CAS, as evidenced by the improved area under the curve (0.85 vs. 0.78) and global chi-square (34.12 vs. 18.1).

Conclusion:^99mTc-DTPA SPECT/CT has the potential to assess inflammatory activity by detecting the involvement of EOMs in GO. Pre-treatment UR provides independent and incremental values for the prediction of PGT treatment response.

99mTc-DTPA SPECT/CT provided guide on triamcinolone therapy in Graves' ophthalmopathy patients

INTRODUCTION

Distinguishing between the active and inactive stages of Graves' ophthalmopathy (GO) is essential for making treatment decisions. 99mTc-DTPA SPECT/CT is sensitive in identifying inflammation in extraocular muscles of GO patients, which we designate 99mTc-DTPA-active. This study aimed to evaluate the response of 99mTc-DTPA-active GO patients to local immunosuppressive therapy.

MATERIALS AND METHODS

Sixty-four 99mTc-DTPA-active GO patients (89 eyes) were retrospectively analyzed. Forty-five patients (64 eyes) received repeated peribulbar triamcinolone injection, and 19 patients (25 eyes) received no immunosuppressive treatment. Ophthalmological assessment, including clinical activity score, eyelid retraction, eyelid aperture, proptosis, diplopia, and ocular mobility, was recorded before and after treatment.

RESULTS

Compared with untreated patients, the clinical activity score decreased significantly (P  < 0.001) while eye symptoms (soft-tissue swelling and eyelid retraction and aperture) improved significantly (P  = 0.02, P  < 0.001, P  < 0.001, respectively) in treated patients after six months. The inferior and medial recti were significantly smaller (P  < 0.001, P  < 0.001, respectively), and 99mTc-DTPA uptake in the two recti was significantly less (P  = 0.001, P  = 0.01, respectively) in treated patients than in untreated patients after 3 months.

CONCLUSION

Clinical activity score of < 3 does not indicate inactive GO, as revealed with 99mTc-DTPA SPECT/CT. Patients with 99mTc-DTPA-active GO can improve the symptoms with peribulbar triamcinolone injection.

Choroidal thickness in thyroid-associated orbitopathy

IMPORTANCE

To investigate the choroidal thickness (CT) in patients with thyroid-associated orbitopathy (TAO).

BACKGROUND

To compare CT of TAO patients and healthy subjects.

DESIGN

Prospective cross-sectional study in a public hospital.

PARTICIPANTS

One hundred and four eyes of 52 TAO patients and 52 eyes of 26 healthy subjects.

METHODS

CT was measured with enhanced-depth imaging optical coherence tomography (EDI-OCT) at the subfoveal, macular and peripapillary regions. Multivariate linear regression was used to evaluate the associations of subfoveal CT with systemic and ocular variables among TAO eyes.

MAIN OUTCOME MEASURES

CT of both groups.

RESULTS

CT of eyes with TAO was significantly increased at the subfoveal region, 1 and 2 mm from the fovea nasally, temporally and superiorly, and 1 mm inferior to the fovea (all P < .05). No significant difference was found in CT at 2 mm inferior to the fovea (P = .094) and all four quadrants of the peripapillary region (superior, P = .096; nasal, P = .732; inferior, P = .179; temporal, P = .052). Among TAO eyes, thinner subfoveal choroid was associated with worsening exophthalmos (P = .043), poorer visual acuity (P = .017), increasing age (P = .040) and axial length (P < .001). There was no association between CT and clinical activity score (P = .239).

CONCLUSIONS AND RELEVANCE

TAO patients showed thicker choroid than controls over the macula, but not the peripapillary regions. Thinner subfoveal choroid was associated with worsening exophthalmos and poorer vision. EDI-OCT can monitor choroidal vascular changes associated with TAO and its complications.

Efficacy of 99mTc-DTPA SPECT/CT in diagnosing Orbitopathy in graves' disease

BACKGROUND

The most frequently used methods of assessing Graves' orbithopathy (GO) include: Clinical Activity Score (CAS), ultrasonography (USG), computed tomography (CT), and magnetic resonance imaging (MRI). There exists another, slightly forgotten, imaging method: single-photon emission computed tomography (SPECT) with the use of diethylenetriaminepentaacetic acid tagged with ^99mTc (^99mTc-DTPA). These days it is possible to conduct a SPECT examination fused with a CT scan (SPECT/CT), which increases the diagnostic value of the investigation. The aim of this paper is to evaluate the usefulness of ^99mTc-DTPA SPECT/CT in diagnosing Graves orbitopathy, as compared with other methods.

METHODS

Twenty-three patients with suspected active (infiltrative-edematous) Graves' orbithopathy were included in the study. Each patient underwent a CAS, an MRI, and a SPECT/CT. The obtained results were analysed statistically, with the assumed statistical significance of p < 0.05.

RESULTS

The SPECT/CT and MRI were found to have the highest sensitivity: 0.93 each. The SPECT/CT had the highest specificity: 0.89. MRI and CAS had lower values: 0.78 and 0.56, respectively. The occurrence of an active form of GO had no impact on the exacerbation of exophthalmos or the thickness of the oculomotor muscles.

CONCLUSIONS

The ^99mTc-DTPA SPECT/CT method provides a very good tool for assessing the active form of GO and can, alongside the MRI scan, be used as a referential diagnostic procedure in GO.