Early versus delayed post-therapy whole body scintigraphy for well-differentiated thyroid carcinoma: A meta-analysis

Introduction@#No clear consensus exists as to the optimal timing for conducting whole body scintigraphy (WBS) after radioactive iodine (RAI) therapy for differentiated thyroid carcinoma. @*Objective@#This study aimed to compare the utility of early versus delayed post-therapy WBS in identifying residual lesions and metastases.@*Methods@#A systematic review of existing literature was done, yielding 6 observational studies relevant to the subject. Meta-analyses were done comparing lesion detecting rates of early (3-4 days post-RAI) and delayed (7-11 days post-RAI) post-therapy WBS for thyroid remnants and metastases in the lymph nodes, lungs, and bone using a random-effects model with odds ratios (OR) and 95% confidence intervals (CIs). A subgroup analysis was also done relating to the type of collimator used in imaging.

El tratamiento paciente específico del hipertiroidismo con radioyodo: una oportunidad a la mejora / Radioiodine treatment of hyperthyroidism with patient-specific techniques: an improvement opportunity

Introducción: La aplicación de actividades fijas en el tratamiento del hipertiroidismo con I131 (yoduro de sodio, conocido también como radioyodo), es el método más usado en nuestro país, a pesar de la individualidad morfo-funcional que caracteriza esta afección. Sin embargo, no existe aún, un consenso internacional sobre la dosis más conveniente para cada caso, y por ende, los resultados no siempre son los deseados. Objetivo: Evaluar la aplicabilidad de varios métodos de cálculo de dosis paciente-específica para el tratamiento de hipertiroidismo con yoduro de sodio. Métodos: Se realizó un análisis de los resultados de varios métodos de cálculo de dosis recomendados internacionalmente a partir de la actividad fija prescrita en 10 pacientes, con el empleo de tecnologías y herramientas ya desarrolladas y disponibles en el país. Se evaluó la variabilidad inter-especialista y su impacto en la dosis planificada para el tratamiento. Resultados: El uso de la información incompleta de la biodistribución y farmacocinética del paciente produjo diferencias entre -42 por ciento y 37 por ciento de las dosis para el mismo paciente. El resultado de la comparación del método de cálculo recomendado por la Sociedad Europea de Medicina Nuclear, manejando la masa por gammagrafía-2D / 3D y por ultrasonido, arrojó diferencias no significativas entre sí. La variabilidad inter-especialista de las actividades prescrita mostró diferencias significativas, que arrojan sobre el mismo paciente, discrepancias entre 44Gy y 243Gy de las dosis terapéuticas a recibir, situación que puede comprometer el éxito del tratamiento y producir efectos secundarios no deseados. Conclusiones: Las técnicas dosimétricas paciente-específicas se pueden implementar satisfactoriamente en nuestro país. Las diferencias numéricas encontradas, especialmente la variabilidad inter-especialista, demuestran la no estandarización terapéutica, lo que apoya el uso de la farmacocinética paciente-específica pre terapéutica y la masa por gammagrafía-3D para planificar el tratamiento siempre que sean posible(AU)

Introduction: Despite of its typical morpho-functional individuality, fixed activities remain as the most used method in Cuba for hyperthyroidism treatment with I (sodium iodide, also known as radioiodine). However, there is not yet an international consensus on the most convenient doses for each case, so, the results are not always the desired ones. Objective: To evaluate the applicability of various patient-specific dose calculation methods for the treatment of hyperthyroidism with sodium iodide. Methods: It was carried out an analysis in 10 patients of the results of some methods for dose calculation from the prescribed fixed activity recommended internationally, with the use of technologies and tools already developed and available in the country. The inter-specialist variability and its impact in the planned dose for the treatment were assessed. Results: The use of uncompleted biodistribution and pharmacokinetics information of the patient showed differences between -42 percent and 37 percent in the doses for the same patient. The outcome of the comparison of the calculation method recommended by the European Society of Nuclear Medicine managing the mass by 3D/2D gammagraphy and ultrasound, presented no significant discrepancies among them. The inter-specialist variability of prescribed activity was statistically significant, and it can produce in the same patient differences between 44Gy and 243Gy of the therapeutic doses, which could affect the treatment success and lead to unnecessary side effects. Conclusions: The patient´s personalized calculation methods can be satisfactorily applied in Cuba. The numeric differences found, especially inter-specialist variability, show the lack of therapeutic standardization, which supports the use of pre-therapeutic patient-specific pharmacokinetics and the mass by 3D-gammagraphy to plan the treatment when possible(AU)

A Retrospective Study of Clinicopathological Profile and Treatment Outcomes of Thyroid Malignancies Presented to a Tertiary Care Teaching Hospital

Introduction: Thyroid cancer is on the developing world over– almost doubling in the past ten years. This is mainly due toimproved awareness, screening and diagnosis of the nodulardisease. Thyroid cancer has an apparent gender predispositionwith women being affected three times more than men and8th most mostly occurring cancer among women. To analyzethe clinicopathological profile of thyroid cancer patients andto assess the pattern of treatment and long-term treatmentoutcomes.Material and methods: The current study was retrospectivecase record review of all the thyroid cancer cases includingall the histopathological confirmed cases of thyroid cancer.The statistical analysis was carried out by using IBM SPSSversion 21.Results: A total of 67 subjects were included with a meanage of 44.72 ± 14.99 years. Females were 68.66% andmales 31.34% of the study population, 61 (91.05%) peoplehad usual presentation of neck swelling of various sizes andother associated findings. Thyroid function test showed that91.04% (61) showed euthyroid status, 40.3% (27) had a totalthyroidectomy, 95.52% (64) of the patients were alive andwell.Conclusion: The study bears evidence to the fact thatpapillary carcinoma is the most commonly occurring formof differentiated thyroid cancer (70.6%). The prevalence ofdistant metastasis is 4.48% and most commonly found in thelung. The disease is more prevalent among women than men

Three-dimensional reconstruction of cervical CT vs ultrasound for estimating residual thyroid volume / 南方医科大学学报

OBJECTIVE@#To compare the accuracy of three-dimensional reconstruction of cervical CT and ultrasound for estimating residual thyroid volume.@*METHODS@#We performed a retrospective analysis of 17 patients with 21 residual thyroid glands undergoing thyroidectomy surgery between February, 2017 and March, 2018 in our department. We compared the residual thyroid volume in preoperative ultrasound with the intraoperative measurement and the volume measured using threedimensional CT reconstruction before surgery.@*RESULTS@#The maximum vertical and anterioposterior diameters of the residual thyroid measured by preoperative ultrasound differed significantly from the volume data measured intraoperatively ( < 0.05), but the difference in the maximum left-right diameters was not statistically significant (>0.05). The maximum vertical, leftright, and anteroposterior diameters estimated by three-dimensional reconstruction of cervical CT was all similar with those measured intraoperatively (>0.05).@*CONCLUSIONS@#Compared with ultrasound examination, three-dimensional reconstruction of neck CT is more accurate for estimating the residual thyroid volume and provides more reliable evidence for clinical calculation of postoperative I dose for thyroid cancer.

Nuclear Theranostics in Turkey / 대한핵의학회잡지

Nuclear theranostics functions as a bridge which connects targeted diagnosis to targeted therapy, just like Turkey functions as a geographical bridge which connects Asia to Europe. This unique geographical site of the country plays an important role with regard to introduction of novel scientific and technologic improvements, which originate from one continent to another, in the era of accelerated information. The first nuclear medicine practice in Turkey started in the beginning of 1950s with the first radioiodine treatment, which actually was a debut for nuclear theranostics in Turkey, years before many other countries in the world. For the time being, along with radioiodine treatment, many other theranostic applications such as I-131 MIBG treatment, Lu-177/Y-90 DOTA peptide treatment, Lu-177 PSMA treatment, Y-90 microsphere treatment, and bone palliative treatment are being performed in many centers countrywide. As science and technology improves, novel theranostic applications are eagerly awaited to be introduced in near future. This paper summarizes the story of nuclear theranostics in Turkey and aims to give an overview on the current status of theranostic applications in Turkey.

Carcinoma papilar de tiroides no captante de radioyodo (I131): a propósito de un caso / Papillary thyroid carcinoma not collecting radioiodine (I131): presentation of a case

RESUMEN El carcinoma papilar de tiroides (CPT) corresponde a una neoplasia frecuente en el mundo y en nuestro país. Generalmente se asocia a buen pronóstico y altas tasas de sobrevida, gracias a características propias del tumor, precisas herramientas diagnósticas y terapias eficaces. Formas infrecuentes de CPT suelen tener comportamientos más agresivos y respuestas parciales a tratamientos habituales, tales como el CPT no captante de radioyodo (5% de los casos). Poca literatura existe respecto a este último y a su manejo. Diversas opciones de tratamiento han sido propuestas, según si hay evidencia de tejido tumoral, como el uso empírico de I131, cirugía, radioterapia, embolización e inhibidores de tirosina kinasa, sin embargo, sigue habiendo una respuesta incierta.

ABSTRACT Papillary thyroid carcinoma (PTC) is a common cancer in the world and in our country. It is usually associated with good prognosis and high survival rates, due to the tumor's characteristics, precise diagnostic tools and effective therapies. Unusual varieties of PTC have more aggressive behaviors and partial responses to usual treatments, such as negative uptake to radioiodine PTC (5% of cases). There is few literature about this variety and its treatment. Diverse treatment options have been proposed, according to whether there is evidence of tumor tissue, such as the empirical use of I131, surgery, radiotherapy, embolization and inhibitors of thyrosine kinase, however an uncertain response remains.

Value of SPECT/CT in Diagnostic I-131 MIBG Scintigraphy in Patients with Neuroblastoma / 대한핵의학회잡지

PURPOSE: Diagnostic I-131 MIBG scintigraphy is an important imaging modality for evaluation of patients with neuroblastoma (NB) especially in centers where I-123 MIBG is not available. Single photon emission computed tomography/computed tomography (SPECT/CT) could potentially improve lesion detection over planar scintigraphy, but studies regarding its usefulness as an add-on to diagnostic I-131 MIBG scintigraphy are limited. This study aimed to determine the usefulness and factors related to usefulness of SPECT/CT in diagnostic I-131 MIBG scintigraphy in NB patients.METHODS: Usefulness of SPECT/CT for lesion detection, lesion localization, resolving suspicious findings, and clarifying the nature of lesions on anatomical imaging were retrospectively reviewed in 86 diagnostic planar I-131 MIBG scintigrams with add-on SPECT/CT.RESULTS: SPECT/CT detected additional lesions in 23.2%(20/86), helped localize lesions in 21.1%(8/38), resolved suspicious findings in 85.7%(6/7), determined functional status of lesions on anatomical imaging in 94.4%(17/18), and changed diagnosis from a negative to a positive study in 19.5%(8/41). Independent predictors of SPECT/CT being useful included presence of suspicious findings on planar imaging (OR 99.08; 95% C.I. 6.99–1404.41; p = 0.001), positive findings on planar imaging (OR 4.61; 95% C.I. 1.05, 20.28; p < 0.001), and presence of structural lesions on anatomical imaging (OR 32.54; 95% C.I. 5.37–196.96; p < 0.001).CONCLUSION: SPECT/CT is a useful add-on to diagnostic planar I-131 MIBG scintigraphy. Predictors of usefulness of SPECT/CT include suspicious or positive findings on planar scintigraphy and the presence of structural lesions on anatomical imaging.

Factors Associated with Dose Determination of Radioactive Iodine Therapy for Differentiated Thyroid Cancer / 대한핵의학회잡지

Radioactive iodine (RAI) therapy for differentiated thyroid cancer has been successfully used for more than 70 years. However, there is still plenty of controversy surrounding the use and doses of radioiodine. There is insufficient evidence to answer the questions. Recent American Thyroid Association (ATA) guidelines seem to favor low-dose RAI, based on recent clinical trials and meta-analyses. However, long-term follow-up data remains limited, and there are additional factors we should consider that might affect the efficacy of RAI therapy. Therefore, until sufficient data are available, it is necessary to remain cautious about determining RAI doses by considering multiple patient-specific variables.

The Predictive Values of Lesion Size, F-18 FDG Avidity and I-131 Avidity for the Clinical Outcome of I-131 Treatment in Patients with Metastatic Differentiated Thyroid Carcinoma Only in the Lung / 대한핵의학회잡지

PURPOSE: We aimed to evaluate the prognostic values of radiography, F-18 FDG PET, and I-131 whole body scans in patients with lung-only metastasis from differentiated thyroid carcinoma (DTC).METHODS: Between 1998 and 2013, we included 31 patients (F: 26, M: 5) with lung-only metastasis from DTC who had been treated with I-131 and underwent PET. Lung metastasis was categorized according to the size (macronodular ≥1.0 cm vs. micronodular <1.0 cm), FDG avidity (avid vs. non-avid), and I-131 avidity (avid vs. non-avid). Progression-free survival (PFS) was evaluated for each patient.RESULTS: Among 31 patients, seven (23%) had macronodular lung metastasis, 26 (84%) had FDG avid lung metastasis, and 16 (52%) had I-131 avid lung metastasis. During the median follow-up period of 9.4 y, median PFS was 6.1 y. Based on Kaplan-Meier analysis, macronodular lung metastasis (p = 0.017) and I-131 non-avid lung metastasis (p = 0.059) were significantly associated with worse outcomes, but FDG avid lung metastasis was not (p = 0.135). Patients with FDG non-avid lung metastasis did not experience disease progression during follow-up, while 11 of 26 patients (42%) experienced disease progression. Based on univariate analysis, the hazard ratio for a poor prognosis was 3.78 (p = 0.029) for macronodular lung metastasis and 3.29 (p = 0.079) for I-131 non-avid lung metastasis.CONCLUSIONS: Macronodular and I-131 non-avid lung metastasis were associated with a poor prognosis in lung-only metastasis from DTC. Although FDG avid lung metastasis may be associated with a poor prognosis, a larger-scale study is needed.

Bilateral Renal Metastasis of Hürthle Cell Thyroid Cancer with Discordant Uptake Between I-131 Sodium Iodide and F-18 FDG / 대한핵의학회잡지

Renal metastasis of thyroid cancer is extremely rare. We report the case of a 62-year-old woman with Hürthle cell thyroid cancer (HCTC) with lungs, bones, and bilateral kidneys metastases. The renal metastatic lesions were clearly demonstrated by ¹³¹I whole body scan (WBS) with SPECT/CT. However, they exhibited false-negative results in ¹⁸F-FDG PET/CT, kidney ultrasonography, and contrast-enhanced CT scan. The findings imply that tumors have low glucose metabolism and are able to accumulate radioiodine, which is not commonly found in the relatively aggressive nature of HCTC. The patient received two sessions of 200 mCi ¹³¹I therapy within 6 months duration. There was complete treatment response as evaluated by the second post-therapeutic ¹³¹I SPECT/CT and serum thyroglobulin. To our knowledge, renal metastasis from HCTC with positive ¹³¹I but negative ¹⁸F-FDGuptake has not been reported in the literature. This case suggests that ¹³¹I SPECT/CTis useful for lesion localization and prediction of ¹³¹I therapy response.

Diagnostic whole body scan (pre‑therapy scan) in differentiated thyroid cancer: A single center community hospital experience.

OBJECTIVE: Diagnostic whole body scan (pre‑therapy scan) with either I‑123 or I‑131 (radioactive isotopes of iodine) is performed to assess the extent of thyroid cancer especially distant metastasis prior to administering the therapeutic dose of I‑131. Our aim of the following study was to determine the utility of the diagnostic pre‑therapy scan in the management of differentiated thyroid cancer. MATERIALS AND METHODS: It was a case‑control study carried out by retrospective chart review, of a randomly selected 100 patients with differentiated thyroid cancer who had followed in our community hospital over the course of 1 year. We collected data on multiple variables in the subjects ‑ including age, gender, pre‑operative size of the nodules, diagnosis, stage of the malignancy, size of the tumor, multifocality, lymphovascular invasion, dose of radioiodine used for remnant ablation, recurrence rates and persistence rates. Continuous variables were compared using the independent sample Mann‑Whitney U‑test whereas the Chi‑square test was used for nominal variables. RESULTS: The mean dose of radioactive iodine administered was 97.56 (±27.98) in the pre‑therapy scan group and it was 97.23 (±32.40) in the control group. There was no difference between the two groups (P ‑ 0.45). There was also no difference in the recurrence rates between the groups (P = 1.0). There was a trend toward a higher degree of persistent cancer in the group that had the pre‑therapy scans (P ‑ 0.086). CONCLUSION: Pre‑therapy scan may not affect the dose of radio‑iodine I‑131 used for remnant ablation of differentiated thyroid cancer and does not influence the recurrence rates. This was especially true with respect to I‑131 remnant ablation for low risk tumors.

High Serum Levels of Thyroid-Stimulating Hormone and Sustained Weight Gain in Patients with Thyroid Cancer Undergoing Radioiodine Therapy

BACKGROUND AND OBJECTIVES: The extent of weight gain and its association with clinical factors in patients undergoing radioiodine therapy for differentiated thyroid cancer remain unclear. We analyzed clinical factors related to sustained weight gain after serum thyroid-stimulating hormone (TSH) stimulation for radioiodine (I-131) therapy. MATERIALS AND METHODS: The study population included 301 adult patients who underwent total thyroidectomy followed by radioiodine therapy and visited the thyroid clinic regularly. Group 1 received a single radioiodine therapy treatment, while group 2 received multiple radioiodine treatment. Data on transient weight gain, defined as weight gain that resolved (±5%) within 1 year after radioiodine therapy, were collected from medical records. Sustained weight gain was defined as body mass index after treatment (BMI(post)) - BMI before treatment (BMI(pre)) ≥2 kg/m2 more than 1 year following radioiodine therapy. Subjective symptoms were scored by questionnaire. Logistic regression analysis was performed using various clinical and laboratory factors to identify risk factors associated with sustained weight gain. RESULTS: Two hundred and fifty-nine (86%) patients showed transient weight gain and 23 (8%) patients showed sustained weight gain. TSH at therapy and T4-on TSH differed significantly in all patients and in the patients in group 1 with sustained weight gain. The proportion of patients with basal BMI≥25 kg/m2 in group 1 with sustained weight gain also differed significantly. Univariate analysis revealed that high serum levels of TSH at therapy (≥100 µIU/mL) and hypercholesterolemia were associated with sustained weight gain in group 1. Multivariate analysis showed that TSH at therapy levels ≥100 µIU/mL was associated with sustained weight gain in group 1. Of 283 patients remaining after excluding those with insufficient TSH suppression during follow-up, T4-on TSH levels were lower in the sustained weight gain group compared to those without sustained weight gain. TSH at therapy levels ≥100 µIU/mL were significantly associated with sustained weight gain in multivariate analysis. CONCLUSION: Most patients (86%) had transient weight gain after TSH at therapy, while 8% of patients showed sustained weight gain. Univariate and multivariate analysis revealed relatively high TSH levels (≥100 µIU/mL) to be a risk factor for patients that received a single dose of radioiodine therapy. Insufficient T4 dose was not associated with sustained weight gain.

Therapy dose calculation in Graves disease using 4-hour I-131 uptake measurements: A retrospective study

Twenty-four-hour radioactive iodine uptake (RAIU) is commonly used to compute for therapy dose in Graves disease (GD). The purpose of this study is to determine the feasibility of using 4-hour RAIU in calculating the dose by correlating 4-hour with 24-hour RAIU and comparing the actual therapy dose using 24-hour RAIU with the computed dose using 4-hour RAIU. A total of 83 GD patients (71% female, 29% male;18-50 years old), who underwent RAI therapy at USTH Section of Nuclear Medicine, were included. There was a strong and positive correlation between 4-hour and 24-hour RAIU values (r=0.736). Paired t-test did not show a statistical difference between the actual given therapy dose based on 24-hour RAIU and the computed therapy dose using 4-hour RAIU (p 0.078). This study showed that therapy dose calculation using 4-hour RAIU can be used in Graves disease patients with no rapid turnover.

Comparación de la eficacia de 3700 MBq con 5550 MBq de radioyodo para ablación del remanente tiroideo en pacientes con cáncer diferenciado de tiroides que presentan metástasis ganglionar locoregional / Comparison of the efficacy of 3700 MBq with 5550 MBq of radioiodine for ablation of the thyroid remnant in patients with differentiated thyroid cancer presenting locoregional ganglionic metastasis

Determinar la eficacia de dos dosis de radioyodo para la ablación del remanente tiroideo en pacientes con Cáncer Diferenciado de Tiroides que presentan metástasis ganglionar locoregional. Metodología: El estudio fue de diseño experimental del tipo muestreo aleatorio simple. La muestra estuvo conformada por 40 pacientes con el diagnóstico de Cáncer diferenciado de tiroides con evidencia de metástasis ganglionar locoregional. Los pacientes fueron inscritos y randomizados en dos grupos, el grupo experimental (3700 MBq I-131) y grupo control (5550 MBq I-131). En relación a nuestro estudio la medición de la eficacia fue un rastreo corporal total con I-131 negativo, porcentaje de captación a las 24 horas < 0,5 por ciento y tiroglobulina sérica < 2 ng/ml. Resultados: Cuando se definió el éxito la ablación, solamente con el rastreo corporal con 1-131 negativo, no se encontraron diferencias entre el grupo de estudio (100 por ciento, P=0.31) y el grupo control (94,4 por ciento, para un P>0.05). Cuando se consideró el rastreo corporal total con I-131 más el valor de corte de la tiroglobulina sérica <2 ng/ml, si hubo diferencia significativa en la tasa de éxito de la ablación entre el grupo de estudio y el grupo control (P=0,006). Conclusión: La eficacia de la ablación del remanente tiroideo usando dosis de 3700 MBq es similar al de 5550 MBq de radioyodo en pacientes con cáncer diferenciado de tiroides que presentan metástasis ganglionar locoregional...

To determine the efficacy of two doses of radioiodine for thyroid remnant ablation in patients with differentiated thyroid cancer presenting locoregional lymph node metastases. Methodology: The experimental study design was simple random sampling type. The sample consisted of 40 patients with a diagnosis of differentiated thyroid cancer with evidence of locoregional lymph node metastases. Patients were enrolled and randomized into two groups, the experimental group (3700 MBq I-131) and control group (5550 MBq I-131). In relation to our study measuring the effectiveness was a total body sean with I-131 negative percentage uptake at 24 hours < 0.5 per cent and serum thyroglobulin < 2 ng/ml. Results: When success was defined ablation, only with the body scintigraphy with I-131 negative, no differences between the study group (100 per cent, P=0.31) and the control group (94.4 per cent, for a P>0.05). When the whole body sean was considered to I-131 over the cutoff value of serum thyroglobulin < 2 ng/ml, if there was significant difference in the success rate of ablation between the study group and the control group (P=0.006). Conclusion: The effectiveness of remaining thyroid ablation using 3700 MBq dose is similar to 5550 MBq of radioactive iodine in patients with differentiated thyroid cancer lymph node metastasis presenting locoregional...

Low Dose versus High Dose Radioiodine Therapy / 대한갑상선학회지

Since 1946, radioiodine (I-131) therapy has been one of the standard treatments for differentiated thyroid cancer (DTC). Recently the occurrence of thyroid cancer was markedly increasing and most of them were limited disease. Several reports said that there is no significant difference of outcome between low and high dose radioiodine therapy in patients with low to intermediate risk category of thyroid cancer. In this review, current effectiveness and toxicity of radioiodine ablation will be compared between low and high dose radioiodine in patient with low to intermediate risk DTC.

Comparison of Radioactivity Measurement with Radionuclide Calibrators in Nuclear Medicine Centers / 의학물리

To acquire good image quality and to minimize unnecessary radiation dose to patients, it is important to ensure that the radiopharmaceutical administered is accurately measured. Quality control of radionuclide calibrators should be performed to achieve these goals. The purpose of this study is to support the quality control of radionuclide calibrators in nuclear medicine centers and to investigate the level of measurement accuracy of the radionuclide calibrators. 58 radionuclide calibrators from 45 nuclear medicine centers, 74 radionuclide calibrators from 58 nuclear medicine centers, and 60 radionuclide calibrators from 45 nuclear medicine centers were tested with I-131, Tc-99m and I-123, respectively. The results showed that 81% of calibrators for I-131, 61% of calibrators for Tc-99m and 67% of calibrators for I-123 were within +/-5%. 17% of calibrators for I-131, 20% of calibrators for Tc-99m and 15% of calibrators for I-123 had a deviation in the range 5%10%. Follow-up measurements were performed on the calibrators whose error exceeded the +/-10% limit. As a result, some of the calibrator showed an improvement and their deviation decreased below the +/-10% limit. The results have shown that such comparisons are necessary to improve the accuracy of the measurement and to identify malfunctioning radionuclide calibrators.

Optimal Imaging Time for Diagnostic I-123 Whole Body Scan in the Follow-up of Patients with Differentiated Thyroid Cancer: Comparison between 6- and 24-Hour Images of the Same Subjects / 핵의학분자영상

PURPOSE: To determine optimal imaging time for diagnostic I-123 whole body scan in the follow-up of patients with differentiated thyroid cancer (DTC), we compared the image quality of 6- and 24-hour images of the same subjects. MATERIALS AND METHODS: Four hundred ninety-eight patients (M:F=55:443, Age 47.6+/-12.9 years) with DTC who had undergone total thyroidectomy and I-131 ablation therapy underwent diagnostic whole body scanning 6 hour and 24 hour after oral ingestion of 185 MBq (5 mCi) of I-123. Serum thyroglobulin measurement and ultrasonography of the neck were performed at the time of imaging. In 40 patients underwent additional I-131 therapy, post-therapy I-131 images were obtained and compared with diagnostic I-123 images. RESULTS: In 440 patients (88.4%), 6- and 24-hour diagnostic I-123 images were concordant, and 58 patients (11.6%) showed discordant findings. Among 58 discordant patients, 31 patients showed abnormal tracer uptake on only 6-hour image, which turned out false-positive findings in all cases. In 12 patients with positive findings on only 24-hour image, remnant thyroid tissue (4 patients) and cervical lymph node metastasis (3 patients) were presented. Among 40 patients underwent additional I-131 therapy, 6-hour and 24-hour images were discordant in 13 patients. All 5 patients with abnormal uptake on only 6-hour image revealed false-positive results, whereas most of 24-hour images were concordant with post-therapy I-131 images. CONCLUSION: I-123 imaging at 24-hour could reduce false-positive findings and improve diagnostic accuracy, compared with 6-hour image in the follow-up of patient with DTC.

Investigation of Scatter and Septal Penetration in I-131 Imaging Using GATE Simulation / 의학물리

Scatter correction for I-131 plays a very important role to improve image quality and quantitation. I-131 has multiple and higher energy gamma-ray emissions. Image quality and quantitative accuracy in I-131 imaging are degraded by object scatter as well as scatter and septal penetration in the collimator. The purpose of this study was to estimate scatter and septal penetration and investigate two scatter correction methods using Monte Carlo simulation. The gamma camera system simulated in this study was a FORTE system (Phillips, Nederland) with high energy, general-purpose, parallel hole collimator. We simulated for two types of high energy collimators. One is composed of lead, and the other is composed of artificially high Z number and high density. We simulated energy spectrum using a point source in air. We estimated both full width at half maximum (FWHM) and full width at tenth maximum (FWTM) using line spread function (LSF) in cylindrical water phantom. We applied two scatter correction methods, triple energy window scatter correction (TEW) and extended triple energy window scatter correction (ETEW). The TEW method is a pixel-by pixel based correction which is easy to implement clinically. The ETEW is a modification of the TEW which corrects for scatter by using abutted scatter rejection window, which can overestimate or the underestimate scatter. The both FWHM and FWTM were estimated as 41.2 mm and 206.5 mm for lead collimator, respectively. The FWHM and FWTM were estimated as 27.3 mm and 45.6 mm for artificially high Z and high density collimator, respectively. ETEW showed that the estimation of scatter components was close to the true scatter components. In conclusion, correction for septal penetration and scatter is important to improve image quality and quantitative accuracy in I-131 imaging. The ETEW method in scatter correction appeared to be useful in I-131 imaging.

Analysis of Urine Iodine Excretion Decrease by Two-Week Stringent Low Iodine Diet for Remnant Thyroid Ablation with Radioactive Iodine in Korean Patients with Thyroid Cancer; Prospective Study / 핵의학분자영상

A low iodine diet (LID) is the recommended preparation for radioactive iodine treatment. However, the recommended duration and stringency of LID are different among each recommendation. More stringent LID is expected in Korea because Korea is a iodine-rich region. We investigated the decrement of urine iodine excretion by two-week stringent LID for remnant thyroid ablation with radioactive iodine in Korean patients with thyroid cancer, prospectively. MATERIAL AND METHOD: From November 2006, patients who referred to our hospital for remnant ablation after total thyroidectomy were included in this study. To decrease total body iodine, our protocol included three strategies. First, we checked medication which could inhibit the radioactive iodine uptake. Second, the date of I-131 treatment was scheduled at least 3 months later if contrast agent had been used. The last strategy was two-week stringent LID education by specialized nutritionist. Before and after two-week stringent LID, 24hr-urine iodine was analyzed respectively. 24hr-urine creatinine was also analyzed for determining more valid 24hr urine sampling subgroup. RESULTS: Total 51 patients were finally enrolled. Average of 24hr-urine iodine excretion was significantly lowered (787+/-2242 -> 85+/-85 microgram/d, p=0.03) after LID and 74.4% of patients reached below the recommended urine iodine excretion level ( 99+/-116 microgram/d, p=0.05) and 78.6% of patients met the criteria. CONCLUSION: Most patients could reach below the recommended urine iodine level after two-week stringent LID. Therefore, in our opinion, at least two-week stringent LID should be recommended in Korea.

A Significant Discrepancy of Uptake between I-131 MIBG and F-18 FDG in a Patient With Malignant Paraganglioma / 핵의학분자영상

A 38-year-old man who was diagnosed with malignant paraganglioma underwent computed tomography (CT) and I-131 metaiodobenzylguanidine (MIBG) san. CT showed extensive lymph node enlargement in right iliac area and retroperitoneum with severe hydronephrosis and mass on posterior bladder wall. However, I-131 MIBG scan didn't showed abnormal uptake. He also underwent F-18 fluorodeoxyglucose (FDG) positron emisson tomography/CT for localizing accurate tumor site. F-18 FDG PET/CT showed multiple metastases of left supraclavicular, hilar, mediastinal para-aortic, inguinal, right iliac lymph nodes, lung, vertebrae, and pelvis. There are a few reports showing that the F-18 FDG PET/CT is helpful for staging and localizing tumor site of patients who are diagnosed with negative on the MIBG scans. Thus, we report a case with paraganglioma which showed negative I-131 MIBG scan, but revealed multiple intense hypermetabolic foci in F-18 FDG PET/CT.