Application of small bowel capsule endoscopy in children with Meckel's diverticulum.

BACKGROUND: Meckel diverticulum (MD) is an important cause of gastrointestinal bleeding in children. Small bowel capsule endoscopy (SBCE) is a first-line examination method applied to patients with obscure gastrointestinal bleeding, but there are few studies on its application in children with MD. This article aims to provide evidence in favor of the auxiliary diagnosis of MD in children by analyzing its characteristics using SBCE. METHODS: We retrospectively collected the clinical data of patients with suspected MD. RESULTS: A total of 58 children were included in this study. All 58 children presented overt gastrointestinal bleeding (bloody stool or melena). Capsule endoscopy identified protruding lesions in 2 cases, double-lumen changes in 30 cases (all considered as MD), vascular lesions in 7 cases, intestinal mucosal inflammatory lesions in 3 cases, ulcers or erosion in 3 cases, and no obvious abnormalities in SBCE in 12 cases. Both SBCE and technetium-99 scans were performed for 24 cases, 22 of which were diagnosed MD by their combined results, giving a diagnostic coincidence rate of 91.7%. Eight cases were highly suspected as MD but were negative for the technetium-99 scan and positive for SBCE. CONCLUSION: SBCE has high accuracy in the diagnosis of MD in children, especially when performed in combination with a technetium-99 scan, which can greatly improve the diagnostic rate of MD in children.

The Utility of Sulfur Colloid Imaging to Differentiate Charcot's Neuroarthropathy from Osteomyelitis: A Case Study.

Charcot's neuroarthropathy and osteomyelitis can have similar initial presentations. The ability to differentiate between the two pathologic conditions is essential, as each requires different treatment. We present a case of a 53-year-old woman with pain, swelling, and warmth in her left first metatarsophalangeal joint and first tarsometatarsal joint. Radiographs showed comminuted fractures at the base of the first metatarsal. Osteomyelitis was suspected by the primary team based on physical findings and a history of previous first metatarsophalangeal joint arthrodesis. A triphasic bone scan and an indium white blood cell scan were positive for osteomyelitis. The podiatric medical team was suspicious for possible Charcot's neuroarthropathy based on physical findings and uncontrolled blood glucose levels at the time of her previous arthrodesis. A sulfur colloid scan was performed and compared with an indium scan, which showed no evidence of osteomyelitis. This case demonstrates the usefulness of sulfur colloid imaging compared with an indium white blood cell scan to differentiate osteomyelitis from Charcot's neuroarthropathy. This case also highlights the importance of using clinical judgment to make the correct diagnosis.

Ultrasonographic Detective Flow Imaging for Evaluating Parathyroid Adenoma in Patients with Primary Hyperparathyroidism.

BACKGROUND: Detective flow imaging (DFI) is a new imaging technology that displays low-velocity blood flow, which is difficult to visualize on conventional color Doppler ultrasonography (CDU). In this study, we compared the usefulness of DFI with that of CDU and methoxy-isobutyl-isonitrile (MIBI) scintigraphy for detecting parathyroid adenoma (PA) in patients with primary hyperparathyroidism (PHPT). METHODS: From March 2021 to March 2023, 87 PHPT patients underwent surgery, and 66 had a single PA. We performed preoperative conventional ultrasonography with CDU, MIBI scintigraphy, and DFI for 42 patients (5 males and 37 females; mean age: 61.6 ± 15.4 years). RESULTS: MIBI scintigraphy detected PA in 85.7% (36/42) patients, and both CDU and DFI detected PA in all patients. The rates of vascularity in PA detected by CDU and DFI were 71.4% (30/42) and 85.7% (36/42), respectively. Vascularity was detected by DFI in 6 patients who were negative for vascularity on MIBI scintigraphy. Furthermore, DFI detected blood supply in 6 of the 12 patients with undetectable blood supply on CDU. Fisher's exact test revealed that high or low blood flow, as determined by DFI, was significantly associated with detection of feeding vessels in PA by CDU (P < 0.001). CONCLUSIONS: DFI was useful for preoperative detection of PA blood flow.

Scintigraphy of Gastrointestinal Motility: Best Practices in Assessment of Gastric and Bowel Transit in Adults.

Various radiologic examinations and other diagnostic tools exist for evaluating gastrointestinal diseases. When symptoms of gastrointestinal disease persist and no underlying anatomic or structural abnormality is identified, the diagnosis of functional gastrointestinal disorder is frequently applied. Given its physiologic and quantitative nature, scintigraphy often plays a central role in the diagnosis and treatment of patients with suspected functional gastrointestinal disorder. Most frequently, after functional gallbladder disease is excluded, gastric emptying scintigraphy (GES) is considered the next step in evaluating patients with suspected gastric motility disorder who present with upper gastrointestinal symptoms such as dyspepsia or bloating. GES is the standard modality for detecting delayed gastric emptying (gastroparesis) and the less commonly encountered clinical entity, gastric dumping syndrome. Additionally, GES can be used to assess abnormalities of intragastric distribution, suggesting specific disorders such as impaired fundal accommodation or antral dysfunction, as well as to evaluate gastric emptying of liquid. More recently, scintigraphic examinations for evaluating small bowel and large bowel transit have been developed and validated for routine diagnostic use. These can be performed individually or as part of a comprehensive whole-gut transit evaluation. Such scintigraphic examinations are of particular importance because clinical assessment of suspected functional gastrointestinal disorder frequently fails to accurately localize the site of disease, and those patients may have motility disorders involving multiple portions of the gastrointestinal tract. The authors comprehensively review the current practice of gastrointestinal transit scintigraphy, with diseases and best imaging practices illustrated by means of case review. ©RSNA, 2024 See the invited commentary by Maurer and Parkman in this issue.

Scintigraphic and Echocardiographic Study of Patients with Pathogenic or Probably Pathogenic Variants of the TTR Gene without Overt Cardiac Involvement. / Avaliação Cintilográfica e Ecocardiográfica em Portadores de Variantes Patogênicas ou Provavelmente Patogênicas do Gene TTR sem Envolvimento Cardíaco Manifesto.

BACKGROUND: Transthyretin amyloidosis (ATTR) is an infiltrative disease caused by abnormal protein deposition mainly in the heart and peripheral nervous system. When it affects the heart, the disease presents as restrictive cardiomyopathy; when it affects the peripheral and autonomic nervous system, it manifests as polyneuropathy, and is called familial amyloid polyneuropathy (FAP). There are two ATTR subtypes: wild-type ATTR, where there is no mutation, and mutant ATTR (ATTRm), which is characterized by a mutation in the gene encoding the transthyretin protein (TTR). In both subtypes, cardiac involvement is the major marker of poor prognosis. OBJECTIVES: To assess the prevalence of subclinical cardiac involvement in a sample of patients with TTR gene mutation by using pyrophosphate scintigraphy and strain echocardiography; to compare scintigraphy and strain findings; to evaluate the association between neurological manifestations (FAP) and subclinical cardiac involvement; and to analyze whether there is an association between any specific mutation and cardiac involvement. METHODS: This is a cross-sectional study with carriers of the TTR gene mutation, without cardiovascular symptoms or changes in electrocardiographic or conventional echocardiographic parameters. All patients underwent pyrophosphate scintigraphy and strain echocardiography. Subclinical cardiac involvement was defined as a Perugini score ≥ 2, heart-to-contralateral lung (H/CL) ratio ≥ 1.5 at 1 h, H/CL ≥1.3 at 3 h, or global longitudinal strain (GLS) ≤ -17%. Descriptive and analytical analyses were performed and Fisher's exact test and Mann-Whitney test were applied. A value of p < 0.05 was considered significant. RESULTS: The 23 patients evaluated had a median age of 51 years (IQR 37-57 years), 15 (65.2%) were female, 12 (52.2%) were Pardo, nine (39.1%) had systemic arterial hypertension, and nine (39.1%) had a previous diagnosis of FAP. Of the nine patients with FAP, 8 (34.8%) were on tafamidis. The associated mutations were Val142IIe, Val50Met, and IIe127Val. The median GLS in the sample was -19% (-16% to -20%). Of the 23 patients, nine (39.1%; 95% CI = 29-49%) met criteria for cardiac involvement, six (26%) by the GLS-based criteria only. There was no association between having FAP and being an asymptomatic carrier, as assessed by strain echocardiography and pyrophosphate scintigraphy (p = 0.19). The prevalence of systemic arterial hypertension, diabetes mellitus, dyslipidemia, smoking, and reduced GLS did not differ between groups. Septal e' wave velocity was the only variable that significantly differed between individuals with and without reduced GLS, with an area under the ROC curve of 0.80 (95% CI = 0.61-0.98, p = 0.027). The best diagnostic accuracy was achieved with a septal e' velocity ≤ 8.5 cm/s. There was no association between mutation type and preclinical cardiac involvement, nor between tafamidis use and lower degree of cardiac involvement (37.5% versus 40.0%, p = 0.90). CONCLUSION: Subclinical cardiac involvement was common in a sample of TTR mutation carriers without cardiac involvement. Reduced left ventricular GLS was the most frequent finding. There was no association between the presence of amyloid polyneuropathy and subclinical cardiac involvement. Type of mutation was not associated with early cardiac involvement. In this sample, the use of tafamidis 20 mg/day was not associated with a lower prevalence of subclinical cardiac involvement.

FUNDAMENTO: A amiloidose por transtirretina (ATTR) é uma doença infiltrativa causada pela deposição anormal de proteína principalmente no coração e no sistema nervoso periférico. Quando acomete o coração, a doença manifesta-se como uma cardiomiopatia restritiva e, quando afeta o sistema nervoso periférico e autônomo, apresenta-se como uma polineuropatia, podendo ser chamada de Polineuropatia Amiloidótica Familiar (PAF). Existem dois subtipos de ATTR, a ATTR selvagem, em que não há variantes genéticas, e a ATTR hereditária, caracterizada por uma variante no gene que codifica a proteína transtirretina (T\TR). Em ambos os subtipos, o envolvimento cardíaco é o principal marcador prognóstico. OBJETIVOS: Avaliar a prevalência do envolvimento cardíaco subclínico em uma amostra de pacientes com variantes genéticas no gene TTR usando a cintilografia com pirofosfato e o ecocardiograma com strain; comparar os achados cintilográficos e as medidas de strain; avaliar a associação entre PAF e o envolvimento subclínico; e analisar se existe uma associação entre uma variante genética específica e o envolvimento cardíaco. MÉTODOS: Estudo transversal com carreadores de variantes no gene TTR sem sintomas cardiovasculares e sem alterações nos parâmetros da eletrocardiografia ou do ecocardiograma convencional. Todos os pacientes foram submetidos à cintilografia com pirofosfato e à ecocardiografia com análise de strain. O envolvimento cardíaco subclínico, definido como um escore de Perugini ≥ 2, razão Coração (C)/ Hemitórax Contralateral (CL) ≥ 1,5 em uma hora, C/CL ≥ 1,3 na terceira hora, ou um strain longitudinal global (SGL) ≤ −17%. Realizadas análises descritiva e analítica, e aplicados o teste exato de Fisher e o teste de Mann-Whitney. Um valor de p<0,05 foi considerado significativo. RESULTADOS: Os 23 pacientes avaliados apresentavam uma idade mediana de 51 (37-57) anos, 15 (65,2%) eram do sexo feminino, 12 (52,2%) eram pardos, nove (39,1%) apresentavam hipertensão arterial sistêmica, e nove (39,1%) tinham um diagnóstico prévio de PAF. Dos nove pacientes com PAF, oito (34,8%) usavam tafamidis. As variantes genéticas identificadas foram Val142IIe, Val50Met e IIe127Val. O valor mediano do SGL foi −19% (-16% ­ −20%). Dos 23 pacientes, nove (39,1%; 95% CI = 29­49%) preencheram os critérios de envolvimento cardíaco, seis (26%) somente pelo critério do SGL. Não houve associação entre PAF e um carreador assintomático avaliado por ecocardiograma com análise de strain e pela cintilografia com pirofostato (p=0,19). A prevalência de hipertensão arterial sistêmica, diabetes mellitus, dislipidemia, tabagismo e SGL reduzido não foi diferente entre os grupos. A velocidade da onda e' septal foi a única variável que apresentou diferença significativa entre os indivíduos com e sem SGL reduzido, com uma área sob a curva ROC de 0,80 (IC95% = 0,61­0,98, p = 0,027). A melhor acurácia diagnóstica foi alcançada com uma velocidade e' septal ≤ 8,5 cm/s. Não houve associação entre o tipo de variante genética e o envolvimento cardíaco pré-clínico, nem entre o uso de tafamidis e este mesmo envolvimento (37,5% versus 40,0%, p = 0,90). CONCLUSÃO: O envolvimento cardíaco subclínico foi frequente em uma amostra de carreadores da variante genética do gene TTR. Um valor do SGL reduzido foi o achado mais comum. Não houve associação entre a presença de polineuropatia amiloidótica e o envolvimento subclínico. O tipo de variante genética não foi associado com envolvimento cardíaco precoce. Nesta amostra, o uso de tafamidis (20mg/dia) não foi associado com uma menor prevalência de envolvimento cardíaco subclínico.

CT Scan Data Analysis in Malformations of Cortical Development.

Malformations of cortical development (MCDs) are a diverse group of disorders that result from abnormal neuronal migration, proliferation, and differentiation during brain development. Head computed tomography (CT) has limited use in the diagnosis of MCDs and should be reserved for selected cases with specific indications or when magnetic resonance imaging is not available or contraindicated. CT can detect brain calcifications associated with MCDs, thus helping in the differential diagnosis between acquired and genetic MCDs or in the identification of different genetic patterns. Moreover, CT can provide high-resolution images of the skull and bones, thus identifying associated malformations, such as craniosynostosis, inner and middle ear malformations, and vertebral anomalies. In this chapter, we review the CT scan technique, data analysis, and indications in the investigation of MCDs.

Gastrointestinal radionuclide imaging in pediatric age group.

Pediatric gastrointestinal imaging plays a crucial role in evaluating and managing digestive system disorders in children. This comprehensive review dives into the nuances of pediatric gastrointestinal imaging techniques, focusing on three specific modalities: gastric emptying scintigraphy (GES), intestinal transit scintigraphy (ITS), and gastrointestinal bleeding scintigraphy. GES involves real-time monitoring of stomach emptying using radiotracers and gamma camera technology. While challenges exist in standardizing protocols due to age-specific meal compositions, GES remains pivotal in diagnosing motility disorders, gastroesophageal reflux, and abdominal pain in children. ITS, utilizing [67Ga], provides insights into gastrointestinal motility disorders such as Hirschsprung disease. It aids in whole-gut transit evaluation, guiding surgical interventions and improving long-term clinical outcomes. Gastrointestinal bleeding scintigraphy, employing [99mTc], assists in diagnosing conditions like Meckel's diverticulum and occult bleeding, offering continuous monitoring to pinpoint the bleeding site along the entire gastrointestinal tract. SPECT-CT improves the accuracy and the standards of care. Each technique's protocol details, clinical indications, and diagnostic capabilities are thoroughly discussed, highlighting the importance of these non-invasive, functional imaging modalities in pediatric gastroenterology.

Incidental 68Ga-DOTATATE uptake in thyroid nodules: Is guideline-directed management still appropriate?

BACKGROUND: Fluorodeoxyglucose uptake on positron emission tomography imaging has been shown to be an independent risk factor for malignancy in thyroid nodules. More recently, a new positron emission tomography radiotracer-Gallium-68 DOTATATE-has gained popularity as a sensitive method to detect neuroendocrine tumors. With greater availability of this imaging, incidental Gallium-68 DOTATATE uptake in the thyroid gland has increased. It is unclear whether current guideline-directed management of thyroid nodules remains appropriate in those that are Gallium-68 DOTATATE avid. METHODS: We retrospectively reviewed Gallium-68 DOTATATE positron emission tomography scans performed at our institution from 2012 to 2022. Patients with incidental focal Gallium-68 DOTATATE uptake in the thyroid gland were included. Fine needle aspiration biopsies were characterized via the Bethesda System for Reporting Thyroid Cytopathology. Bethesda III/IV nodules underwent molecular testing (ThyroSeq v3), and malignancy risk ≥50% was considered positive. RESULTS: In total, 1,176 Gallium-68 DOTATATE PET scans were reviewed across 837 unique patients. Fifty-three (6.3%) patients demonstrated focal Gallium-68 DOTATATE thyroid uptake. Nine patients were imaged for known medullary thyroid cancer. Forty-four patients had incidental radiotracer uptake in the thyroid and were included in our study. Patients included in the study were predominantly female sex (75%), with an average age of 62.9 ± 13.9 years and a maximum standardized uptake value in the thyroid of 7.3 ± 5.3. Frequent indications for imaging included neuroendocrine tumors of the small bowel (n = 17), lung (n = 8), and pancreas (n = 7). Thirty-three patients underwent subsequent thyroid ultrasound. Sonographic findings warranted biopsy in 24 patients, of which 3 were lost to follow-up. Cytopathology and molecular testing results are as follows: 12 Bethesda II (57.1%), 6 Bethesda III/ThyroSeq-negative (28.6%), 1 Bethesda III/ThyroSeq-positive (4.8%), 2 Bethesda V/VI (9.5%). Four nodules were resected, revealing 2 papillary thyroid cancers, 1 neoplasm with papillary-like nuclear features, and 1 follicular adenoma. There was no difference in maximum standardized uptake value between benign and malignant nodules (7.0 ± 4.6 vs 13.1 ± 5.7, P = .106). Overall, the malignancy rate among patients with sonography and appropriate follow-up was 6.7% (2/30). Among patients with cyto- or histopathology, the malignancy rate was 9.5% (2/21). There were no incidental cases of medullary thyroid cancer. CONCLUSION: The malignancy rate among thyroid nodules with incidental Gallium-68 DOTATATE uptake is comparable to rates reported among thyroid nodules in the general population. Guideline-directed management of thyroid nodules remains appropriate in those with incidental Gallium-68 DOTATATE uptake.

Unsupervised OCT image despeckling with ground-truth- and repeated-scanning-free features.

Optical coherence tomography (OCT) can resolve biological three-dimensional tissue structures, but it is inevitably plagued by speckle noise that degrades image quality and obscures biological structure. Recently unsupervised deep learning methods are becoming more popular in OCT despeckling but they still have to use unpaired noisy-clean images or paired noisy-noisy images. To address the above problem, we propose what we believe to be a novel unsupervised deep learning method for OCT despeckling, termed Double-free Net, which eliminates the need for ground truth data and repeated scanning by sub-sampling noisy images and synthesizing noisier images. In comparison to existing unsupervised methods, Double-free Net obtains superior denoising performance when trained on datasets comprising retinal and human tissue images without clean images. The efficacy of Double-free Net in denoising holds significant promise for diagnostic applications in retinal pathologies and enhances the accuracy of retinal layer segmentation. Results demonstrate that Double-free Net outperforms state-of-the-art methods and exhibits strong convenience and adaptability across different OCT images.

A Rare False-Positive Whole-Body Scan in a Patient With Differentiated Thyroid Cancer: Unilateral Conjunctival Concretions.

ABSTRACT: 131 I has been used effectively over the years in both diagnosis and therapy of differentiated thyroid cancer (DTC). Although whole-body scan with 131 I is a highly sensitive tool for detecting normal thyroid tissue and metastasis of DTC, it is not specific; therefore, false-positive images can be seen in clinical practice, and their recognition is critical for correct management. Evaluation of false-positive uptake is important because it may be confused with metastatic involvement. Here, we present a rare false-positive result of whole-body scan in a patient with DTC. To our knowledge, it is the first report on 131 I uptake of conjunctival concretions.

Radioiodine Uptake at Suture Site Granuloma Mimicking Neck Node Metastasis on 131 I Whole-Body Iodine Scintigraphy.

ABSTRACT: Differentiated thyroid carcinoma constitutes over 90% of all thyroid cancers. The standard treatment approach involves total or near-total thyroidectomy with or without neck dissection followed by 131 I whole-body scintigraphy (WBS) to detect local or distant metastases. Radioiodine offers high sensitivity and specificity for detection of metastatic disease in well differentiated thyroid carcinoma. However, despite its high accuracy, 131 I WBS demonstrates false-positive results, mostly at inflammatory or infective site. These false-positive radioiodine accumulation can lead to misdiagnosis and unwarranted radioiodine treatment. This case presents localization of 131 I to the suture site granuloma leading to false-positive results on 131 I WBS.

The value of ultrasound in combination with 99mTc-MIBI imaging department of ultrasound medicine, for the diagnosis of ectopic parathyroid glands in the thyroid gland in patients with secondary hyperparathyroidism.

To investigate the value of preoperative ultrasound combined with 99mTc-MIBI imaging for the diagnosis of ectopic intrathyroid parathyroid gland (ETPG) in patients with secondary hyperparathyroidism (SHPT). One hundred and eleven patients with SHPT who underwent total parathyroidectomy plus forearm transplantation from January 2015 to January 2022 in the Third Hospital of Hebei Medical University were selected. All patients underwent routine preoperative ultrasonography and 99mTc-MIBI imaging, and with pathological diagnosis as the gold standard, the clinical data of ETPG patients were selected, including clinical manifestations, laboratory tests, preoperative ultrasonography and 99mTc-MIBI imaging for localization and diagnosis, intraoperative exploration and postoperative pathology, and postoperative follow-up. To analyze the ultrasound manifestations of preoperative parathyroid hyperplasia and the results of 99mTc-MIBI imaging in patients with ETPG. Among 111 patients with SHPT, there were 5 patients with ETPG, 1 male and 4 females with a mean age of (45.00 ±â€…5.05) years, and 6 ectopic parathyroid glands were located in the thyroid gland. The incidence of ETPG was 4.5% (5/111), 4 were detected by ultrasound, 2 were not detected with a diagnostic accuracy of 66.7% (4/6), 3 were positive for 99mTc-MIBI imaging, 3 were negative with a diagnostic accuracy of 50.0% (3/6). Among them, one was not detected by ultrasound, but was positive for 99mTc-MIBI imaging, 2 with negative 99mTc-MIBI imaging, but all were detected by ultrasound, and one with negative 99mTc-MIBI imaging was detected by ultrasound but misdiagnosed as a thyroid nodule. A total of 5 ETPGs were detected by ultrasound combined with 99mTc-MIBI imaging, with a diagnostic accuracy of 83.3% (5/6). Patients' postoperative serum calcium and serum parathyroid hormone (PTH) levels were normalized or significantly decreased from preoperative levels. Ultrasound combined with 99mTc-MIBI imaging can achieve higher accuracy than either examination alone in the preoperative localization and diagnosis of ETPG in SHPT patients.

Hepatopulmonary syndrome: Case report of the evidence of intrapulmonary shunt on 99mTc-MAA scintigraphy and contrast transthoracic echocardiography.

The hepatopulmonary syndrome (HPS) is characterized by arterial oxygenation defect induced by intrapulmonary vascular dilatations in the setting of liver disease. We report a 57-year-old woman with a history of liver cirrhosis presented with progressive cyanosis, exertional dyspnea and a dry cough. Oxyhemoglobin saturation was 88.5% on room air. Contrast transthoracic echocardiography (cTTE) and technetium-99m-macroaggregated albumin (99mTc-MAA) scintigraphy showed an intrapulmonary shunting and confirmed HPS.

Multimodal radionuclide shuntography for device patency: New procedural tips for anuncommon historical technique.

Cerebrospinal fluid (CSF) shunting is an established long-term treatment option for hydrocephalus, and is one of the most commonly performed neurosurgical procedures in western countries.Despite advances in CSF shunt design and management, its failure rates remain high and is most commonly due to obstruction and infection.Cerebrospinal fluidshunt failure diagnosis should be prompt and accurate in establishing timely if its revision is appropriate. Radionuclide shuntography with technetium-99m-diethylenetriaminepetaacetic acid (99mTc-DTPA) is a useful technique for evaluation CSF shunts and management of patients presenting with shunt-related problems, in particular it can avoid unnecessary replacement interventions. Although its execution and interpretation require specific skills, we suggest its execution for the evaluation of device's patency. We here describe the radionuclide shuntography performed with recent hybrid multimodal technologies, with a procedure customized to a complicated patient with hydrocefalus and neoplastic disease. We suggest considering radionuclide shuntography in association with conventional imaging and strongly recommend the additional performance of single photon emission computed tomography/computed tomography (SPECT/CT) because it also provides valuable information to complete the interpretation of planar images.

Optimizing the indication of initial radioiodine oncolytic treatment for metastatic differentiated thyroid cancer by diagnostic 131I scan.

AIM: As a classic theranostic radiopharmaceutical, radioiodine (131I) has been utilized in the management of differentiated thyroid cancer (DTC) for more than 8 decades, and the refinement of its clinical practice has been raised recently. This study was conducted to evaluate the efficiency of a diagnostic (Dx) 131I scan in optimizing the indication of initial radioiodine oncolytic treatment (ROT) for metastatic DTC by predicting therapeutic outcomes. RESULTS: A total of 100 patients (Dx positive, n=29; Dx negative, n=71) were eligible for patient-based analysis. The matching rate was 83.0% between the Dx and the post-therapeutic scans (kappa = 0.648, P<0.001). The biochemical remission rate and structural shrinkage rate induced by the initial ROT in the Dx-positive group were, respectively, greater than those in the Dx-negative group (83.3% vs. 17.4%, P<0.001; 37.9% vs. 4.2%, P<0.001). Notably, the predictive values of positive Dx scans for ROT responsiveness and negative Dx scans for ROT nonresponsiveness reached up to 89.7% and 84.5%, respectively. CONCLUSION: This Dx scan approach seems viable in characterizing the 131I-avidity of metastatic DTC and plays a pivotal role in optimizing the indication of initial ROT for metastatic DTC.