The Role of Tc-99 m-MIBI Scan in the Assessment of the Cystic Thyroid Nodule.

PURPOSE: A non-surgical therapeutic option requires assurance that a cystic thyroid nodule with non-diagnostic cytology is benign. This work was undertaken to determine whether Tc-99 m-MIBI scan (MIBI) findings can guide the best therapeutic option with confidence. MATERIAL AND METHODS: We studied 81 cystic non-functioning thyroid nodules with non-diagnostic fine-needle aspiration biopsy (FNAB) report classified according to ATA 2015 ultrasonography (US) patterns for suspicion of malignancy. All had a MIBI to assess metabolic activity within the nodule as well as histopathological diagnosis. Diagnostic value analysis of MIBI as compared to the US pattern was determined. RESULTS: None of the 11 patients with US pattern of benign showed positive MIBI, and all had a histopathological report of benign. Diagnostic value of MIBI on US pattern of very low suspicion showed sensitivity, specificity, PPV, and NPV of 100%, 78.9%, 42.9%, and 100%, respectively. CONCLUSION: Our data shows that the only approach to a safe non-surgical treatment option in a cystic nodule with non-diagnostic FNAB is when no metabolic activity is seen on MIBI.

Towards in vivo imaging of cancer sialylation.

In vivo assessment of tumor glucose catabolism by positron emission tomography (PET) has become a highly valued study in the medical management of cancer. Emerging technologies offer the potential to evaluate in vivo another aspect of cancer carbohydrate metabolism related to the increased anabolic use of monosaccharides like sialic acid (Sia). Sia is used for the synthesis of sialylated oligosaccharides in the cell surface that in cancer cells are overexpressed and positively associated to malignancy and worse prognosis because of their role in invasion and metastasis. This paper addresses the key points of the different strategies that have been developed to image Sia expression in vivo and the perspectives to translate it from the bench to the bedside where it would offer the clinician highly valued complementary information on cancer carbohydrate metabolism that is currently unavailable in vivo.

TSH alone is not sufficient to exclude all patients with a functioning thyroid nodule from undergoing testing to exclude thyroid cancer.

PURPOSE: The purpose of the study was to analyze whether the thyroid-stimulating hormone (TSH) alone avoids tests to exclude malignancy in all patients with functional thyroid nodules (FTN). METHODS: Sixty-nine patients with FTN on (99m)Tc scintigraphy, radioiodine uptake test (RIU), (99m)Tc thyroid uptake, TSH assay, T3, and T4 obtained within 48 h were retrospectively identified out of 2,356 thyroid scans performed from January 2000 to April 2007. FTNs were classified as causing total, partial, or no inhibition of the thyroid as group 1, 2, or 3, respectively. RESULTS: TSH was subnormal in 21 of 69 (30.43%) patients. In group 1 (N = 23, 33.3%), TSH was subnormal, normal, and high in eight, nine, and six patients; in group 2 (N = 17, 24.6%), TSH was subnormal, normal, and high in four, six, and seven patients, and in group 3 (N = 29, 42%), TSH was subnormal, normal, and high in 9, 13, and 7 patients, respectively. TSH was significantly lower in group 1. In T3, T4, (99m)Tc thyroid uptake, and RIU, there were no differences between the three groups. CONCLUSIONS: Only 30.43% of patients had subnormal TSH. TSH alone cannot avoid tests to exclude malignancy in all patients with FTN. FTN existence can only be accurately assessed by thyroid scintigraphy. The current incidence of FTN may be unknown because scintigraphy is not routinely performed in all patients with thyroid nodules. Thyroid scintigraphy of patients with high TSH can detect diseases such as Hashimoto's thyroiditis and identify patients with FTN in whom no further diagnostic procedures would be needed in patients with normal TSH levels with nondiagnostic fine-needle aspiration results.

Combined use of fine-needle aspiration biopsy, MIBI scans and frozen section biopsy offers the best diagnostic accuracy in the assessment of the hypofunctioning solitary thyroid nodule.

PURPOSE: The probability of malignancy is increased in hypofunctioning solitary thyroid nodules (HFNs). Fine-needle aspiration biopsy (FNA), (99m)Tc-methoxyisobutylisonitrile (MIBI) and frozen section biopsy (FS) have limited independent diagnostic accuracy for the differential diagnosis of HFNs. The goal of this study was to assess the accuracy of the three independent diagnostic methods in distinguishing between benign and malignant disease. METHODS: A total of 130 patients with an HFN on the (99m)Tc-pertechnetate scan were included in this study. FNA, MIBI scans, FS, thyroidectomy and histological analysis of surgical specimens for final diagnosis were performed in all patients. RESULTS: Of the 130 patients, 80 (61.54%) had benign lesions and 50 (38.46%), malignant lesions. FNA was diagnostic in 78/130 (60%) patients and non-diagnostic in 52/130 (40%) patients. None of the patients with a negative MIBI scan had a final histological diagnosis of malignancy, and MIBI scans were negative in 38.46% of patients with non-diagnostic FNA results. FS was diagnostic in 104/130 (80%) patients and non-diagnostic in 26/130 (20%) patients. Sensitivity, specificity, positive and negative predictive values and positive and negative likelihood ratios were 81.3%, 97.8%, 96%, 88%, 36.95 and 0.19 respectively for FNA; 100%, 61.3%, 61.7%, 100%, 2.58 and 0 respectively for MIBI; and 80.5%, 100%, 100%, 89%, 0 and 0.2 respectively for FS. Use of both MIBI scans and FS in patients with non-diagnostic FNA rendered a specificity and sensitivity of 100%. CONCLUSION: MIBI scans exclude malignancy in a significant proportion of patients with non-diagnostic FNAs (38% in this study). Cystic nodules with a positive MIBI scan should be further investigated even when the FNA result indicates a benign lesion. Combined use of FNA, MIBI and FS offers the best diagnostic accuracy.

Biokinetics of (99m)Tc-UBI 29-41 in humans.

Antimicrobial peptides have been proposed as new agents to distinguish between bacterial infections and sterile inflammatory processes. (99m)Tc-UBI labeled by a direct method has shown high in vitro and in vivo stability, specific uptake at the site of infection, rapid background clearance, minimal accumulation in non-target tissues and rapid detection of infection sites in mice. The aim of this study was to establish a (99m)Tc-UBI biokinetic model and evaluate its feasibility as an infection imaging agent in humans. Whole-body images from 6 children with suspected bone infection were acquired at 1, 30, 120, 240 min and 24 h after (99m)Tc-UBI administration. Regions of interest (ROIs) were drawn around source organs (heart, liver, kidneys and bladder) on each time frame. The same set of ROIs was used for all 6 scans and the cpm of each ROI were converted to activity using the conjugate view counting method. Counts were corrected by physical decay and by the background correction factor derived from preclinical phantom studies. The image sequence was used to extrapolate (99m)Tc-UBI time-activity curves in each organ and calculate the cumulated activity (A). Urine samples were used to obtain the cumulative percent of injected activity (% I.A.) versus time renal elimination. The absorbed dose in organs was evaluated according to the general equation described in the MIRD formalism. In addition, (67)Ga-citrate images were obtained from all the patients and used as a control. Biokinetic data showed a fast blood clearance with a mean residence time of 0.52 h. Approximately 85% of the injected activity was eliminated by renal clearance 24 h after (99m)Tc-UBI administration. Images showed minimal accumulation in non-target tissues with an average target/non-target ratio of 2.18 +/- 0.74 in positive lesions at 2 h. All infection positive(99m)Tc-UBI images were in agreement with those obtained with (67)Ga-citrate. The mean radiation absorbed dose calculated was 0.13 mGy/MBq for kidneys and the effective dose was 4.34 x 10(-3)mSv/MBq.

Frecuencia de enfermedad tiroidea autoinmune en niños con diabetes mellitus tipo 1 / Frequency of autoimmune thyroid disease in children with type 1 diabetes mellitus

Introducción. Los reportes en la literatura mundial informan una prevalencia de enfermedad tiroidea en pacientes con diabetes mellitus insulino-dependiente de 7.3 a 23.4 por ciento y se ha identificado como factor de riesgo de enfermedad tiroidea a los anticuerpos microsomales (ACM). Los objetivos de este estudio fueron determinar la frecuencia de enfermedad tiroidea en la población de pacientes diabéticos tipo 1 y la prevalencia de ACM en dichos pacientes.Material y métodos. Estudio observacional, transversal y descriptivo. Se estudiaron pacientes con diabetes mellitus tipo 1 que acudieron al Departamento de Endocrinología del Hospital Infantil de México Federico Gómez de febrero a septiembre de 1998. A todos los pacientes se les realizó palpación del cuello en búsqueda intencionada de bocio, perfil tiroideo y anticuerpos microsomales. Los resultados se evaluaron por medio de la prueba t de Student, chi cuadrada y los valores predictivos con análisis Bayesiano.Resultados. De los 108 pacientes, 41 correspondieron al género masculino y 67 al femenino. Se encontraron 13.9 por ciento de pacientes con bocio, 18.3 por ciento con disfunción tiroidea y 6.4 por ciento con ACM positivos. Predominó el bocio eutiroideo con 53.3 por ciento, seguido de bocio hipotiroideo en 33.3 por ciento. El hipotiroidismo se encontró posterior al inicio de la diabetes mellitus tipo 1 (2.76 ñ 0.9 años) y el hipertiroidismo fue prácticamente concomitante (0.42 ñ 0.5). Se encontró un valor predictivo positivo de 71 por ciento y un valor predictivo negativo de 86 por ciento para disfunción tiroidea con ACM, considerándose éstos como un factor de riesgo y no como un factor determinante.Conclusiones. Se encontró una frecuencia elevada de pacientes diabéticos tipo 1 con bocio y disfunción tiroidea. Se recomienda la realización de perfiles tiroideos anuales en estos pacientes.

La gammagrafía hepatobiliar en el diagnóstico diferencial de la atresia de vías biliares / Hepatobiliary scinatigraphy in the differential diagnosis of biliary atresia and neonatal hepatitis

La gammagrafía hepatobiliar es capaz de diferenciar entre atresia de vías biliares y hepatitis neonatal si el procedimiento se realiza cuando aún el daño hepatocelular del paciente no es grave. La gammagrafía, el ultrasonido y la biopsia hepática son todos métodos complementarios con indicaciones y limitaciones, por lo que deben ser empleados en conjunto y en el orden adecuado para establecer un diagnóstico temprano que repercuta en el tratamiento oportuno de estos pacientes.