Falso negativo de la gammagrafía con 99mTc-sestamibi en un carcinoma paratiroideo con tumores pardos asociados. Aportaciones de la PET/TAC-18F-FDG / False negative of the scintigraphy with 99mTc-sestamibi in parathyroid carcinoma with associated brown tumors. Contributions of the 18F-FDG-PET/CT

El carcinoma paratiroideo (CPT) es un tumor poco frecuente que suele ser hiperfuncionante, produciendo un exceso de hormona paratiroidea. El hiperparatiroidismo produce trastornos del metabolismo óseo, como osteopenia y en ocasiones tumores pardos. Los tumores pardos son lesiones óseas benignas, pero localmente destructivas, cuyo diagnóstico diferencial con metástasis u otros tipos de tumores primarios puede ser complicado. La técnica habitual para la detección de patología paratiroidea es la gammagrafía con 99mTc-sestamibi, con una sensibilidad del 85–100% y una especificidad cercana al 100% en adenomas paratiroideos, presentando cifras muy similares en la detección del CPT. Presentamos el caso de un paciente diagnosticado de hiperparatiroidismo de origen tumoral con lesiones óseas asociadas en el que la gammagrafía con 99mTc-sestamibi presentó un falso negativo en la detección de patología paratiroidea. Sin embargo, la PET/TAC-18F-FDG detectó el CPT y ayudó en el diagnóstico diferencial de las lesiones óseas asociadas, que fueron finalmente tumores pardos(AU)

Parathyroid carcinoma (PTC) is a rare malignant disease that is usually hyperfunctioning, which produces an excess of parathyroid hormone. Hyperparathyroidism causes bone metabolism disorders, as osteopenia and sometimes brown tumors. Brown tumors are benign but locally aggressive bone lesions, whose differential diagnosis with metastases or other primary malignancies may be complicated. 99mTc-Sestamibi scan is the usual procedure for the detection of parathyroid pathology, with a sensitivity of 85–100% and specificity close to 100% in parathyroid adenomas, it having similar percentages in the detection of PTC. We present the case of a patient diagnosed of a malignant hyperparathyroidism associated with bone lesions in which the 99mTc-Sestamibi scan showed a false negative result in the detection of parathyroid condition. However, 18F-FDG-PET/CT detected the PTC and helped in the differential diagnosis of associated bone lesions, which were finally confirmed as brown tumors(AU)

[False negative of the scintigraphy with 99mTc-sestamibi in parathyroid carcinoma with associated brown tumors. Contributions of the 18F-FDG-PET/CT]. / Falso negativo de la gammagrafía con 99mTc-sestamibi en un carcinoma paratiroideo con tumores pardos asociados. Aportaciones de la PET/TAC-18F-FDG.

Parathyroid carcinoma (PTC) is a rare malignant disease that is usually hyperfunctioning, which produces an excess of parathyroid hormone. Hyperparathyroidism causes bone metabolism disorders, as osteopenia and sometimes brown tumors. Brown tumors are benign but locally aggressive bone lesions, whose differential diagnosis with metastases or other primary malignancies may be complicated. (99m)Tc-Sestamibi scan is the usual procedure for the detection of parathyroid pathology, with a sensitivity of 85-100% and specificity close to 100% in parathyroid adenomas, it having similar percentages in the detection of PTC. We present the case of a patient diagnosed of a malignant hyperparathyroidism associated with bone lesions in which the (99m)Tc-Sestamibi scan showed a false negative result in the detection of parathyroid condition. However, (18)F-FDG-PET/CT detected the PTC and helped in the differential diagnosis of associated bone lesions, which were finally confirmed as brown tumors.

[Quality control dose calibrators]. / Control de calidad de activímetros.

We have reviewed the legislation about the quality control of dose calibrator. The importance of verifying the correct work of these instruments, is fundamental in daily practice of radiopharmacy and nuclear medicine. The Spanish legislation establishes to include these controls as part of the quality control of radiopharmaceuticals, and the program of quality assurance in nuclear medicine. We have reviewed guides and protocols from international eminent organizations, summarizing the recommended tests and periodicity of them.

Diagnóstico de hipertensión vasculorrenal mediante gammagrafía renal con 99mTc-DMSA pre y postcaptopril / Diagnosis of vasculorenal hypertension by pre- and post-captopril renal scintigraphy with 99mtc-dmsa

Objetivo: Valorar la utilidad de los estudios con 99mTc-DMSA pre y postcaptopril (imagen gammagráfica y función renal unilateral) para identificar el origen vasculorrenal o renal de la enfermedad en pacientes hipertensos con alta sospecha clínica de hipertensión vasculorrenal. Pacientes y Métodos: Se han estudiado 27 pacientes hipertensos (12 varones, 15 mujeres) de edades comprendidas entre 23 y 65 años (edad media 49 años, DE: 9,46) con alta sospecha clínica de hipertensión vasculorrenal, a los que se les realizó protocolo general analítico, ecográfico y radiológico incluyendo arteriografía renal que se utilizó como gold standard. A todos se les practicaron dos estudios gammagráficos con 99mTc-DMSA, uno basal y otro una hora después de la administración de 50 mg de captopril, con una semana de intervalo entre ambos. Los estudios gammagráficos se obtuvieron a las 4 horas de la administración de 3 mCi (111MBq) de 99mTc-DMSA, obteniéndose imágenes en anterior y posterior, y evaluándose los resultados cualitativamente y cuantitativamente mediante el cálculo de la función renal unilateral porcentual. Se consideraron positivos para hipertensión vasculorrenal los estudios con disminución de 5 puntos porcentuales de la función renal unilateral porcentual o la aparición de un defecto nuevo no existente en el estudio basal. Los resultados gammagráficos fueron comparados con el estudio arteriográfico para determinar la sensibilidad y valores predictivos. Resultados: El estudio arteriográfico demostró la existencia de un 18,5 por ciento de pacientes con estenosis de la arteria renal angiográficamente significativa ( > 50 por ciento de la luz).Los estudios gammagráficos pre y postcaptopril con 99mTcDMSA mostraron una sensibilidad del 60 por ciento, especificidad del 91 por ciento, valor predictivo positivo del 60 por ciento y valor predictivo negativo del 91 por ciento. Se identificaron 3 pacientes con defectos de captación segmentarios compatibles con cicatrices pielonefríticas crónicas. Conclusiones: Los estudios con 99mTc-DMSA basal y tras captopril presentan una alta especificidad y son útiles en pacientes con alta sospecha clínica de hipertensión vasculorrenal, identificando adecuadamente un alto porcentaje de pacientes con estenosis arterial renal significativa. La capacidad del DMSA para identificar la presencia o ausencia de anomalías renales, sobre todo cicatrices pielonefríticas, aporta un valor añadido a los estudios de renograma tras IECAs con otros trazadores pudiendo identificar causas renales de hipertensión diferentes a la estenosis de la arteria renal (AU)

[Diagnosis of renovascular hypertension by pre- and post-captopril renal scintigraphy with 99mTc-DMSA]. / Diagnóstico de hipertensión vasculorrenal mediante gammagrafía renal con 99mTe-DMSA pre y postcaptopril.

AIM: Value the utility of studies with 99mTc-DMSA with captopril (scintigraphy imaging and unilateral renal function) in identifying renovascular disease or renal disease in hypertension patients with high probability of renovascular hypertension. METHODS: We studied 27 hypertension patients (12 males, 15 females) mean age 49 years, SD: 9.46, with high probability of renovascular disease. General analysis and radiology was made to all of them including renal arteriography as gold standard. Two renal scintigraphies with 99mTc-DMSA were made to all of them, baseline study and one hour after administration of 50 mg of captopril, a week between both studies. Renal scintigraphy (anterior and posterior images) was obtained 4 hours after the administration of 111 MBq (3 mCi) of 99mTc-DMSA and results were evaluated quantitatively and qualitatively calculating unilateral renal function. We considered positive for renovascular hypertension studies with decrease of more than five percentual points in unilateral renal function or a new defect absent in baseline study. Scintigraphic results were compared with arteriography to determine sensitivity, specificity and predictive values. RESULTS: Arteriography demonstrated significant renal artery stenosis in 18.5% of patients. Renal scintigraphy with captopril using 99mTc-DMSA demonstrated sensitivity of 60%, specificity of 91%, positive predictive value of 60% and negative predictive value of 91%. We identified 3 patients with segmental defects of uptake consistent with chronic pyelonephritis scarring. CONCLUSIONS: Studies with 99mTc-DMSA using captopril present high specificity and are useful in patients with high probability for renovascular hypertension, identifying high number of patients with significant renal artery stenosis. The utility of DMSA in identify renal abnormalities, as specially pyelonephritis scarring, add value to renal studies with captopril using others tracers. DMSA could identify renal etiologies of renovascular hypertension different to renal artery stenosis.

False positive thallium-201 SPECT imaging in brain abscess.

Three cases of intracranial 201Tl uptake, reported as positive tumour activity in patients with a final diagnosis of abscess, are described. 201Tl has been proposed as a useful oncotropic radiotracer in the diagnosis of brain tumour activity. These cases suggest a note of caution in the interpretation of 201Tl brain images in the differential diagnosis of an intracranial expanding mass.

[A comparative study of 9 cases of adrenal pheochromocytoma and 11 cases of extra-adrenal pheochromocytoma]. / Estudio comparativo de nueve casos con feocromocitoma adrenal y once casos con feocromocitoma extraadrenal.

Twenty patients with the diagnosis of pheochromocytoma were studied from January 1990 to January 1998. Nineteen patients had a pathologic investigation performed. The mean age of patients was 49 +/- 16 years (range: 24-71 years), 8 males and 12 females. Nine cases corresponded to adrenal and eleven to extra-adrenal (paragangliomas) pheochromocytomas. The anatomic location was similar in both adrenal glands and for paragangliomas the cervical location predominated. The most consistent clinical finding in our patients was maintained arterial hypertension, followed by headache, palpitations and flushing. Biochemically, an increase in urine catecholamine levels or their metabolites was found in 82.2%. The clonidine test was very useful, particularly for cases where biochemical results were discrepant. CT, NMR and gammagraphy with 123I-MIBG have a high sensitivity for locating pheochromocytomas. NMR and gammagraphy with 111In-pentetreotide located cases in which CT or 123I-MIBG were negative. Preoperative treatment with adrenergic alpha-blockers allowed to surgery with no arterial tension complications. Only one patient with multiple abdominal paragangliomas relapsed. No differences regarding clinical manifestations, biochemical parameters or imaging studies were found between pheochromocytomas and paragangliomas, except their location.

[Gastric emptying as an etiopathogenic factor in gastroesophageal reflux disease]. / Estudio de la evacuación gástrica como factor etiopatogénico de la enfermedad por reflujo gastroesofágico.

The aim of this study is to evaluate gastric emptying change in patients with gastroesophageal reflux (GER). To this purpose, 36 patients with GER diagnosis and 18 control subjects have been studied. GER diagnosis was achieved by means of endoscopy, biopsy and 24 h continuous pH monitoring. Gastric emptying studies were performed on a two day basis, similar labelling meals were provided to patients and control subjects. Those consisted in a one-egg omelette, chicken (110 gr) and orange juice (200 ml). On first day liquid phase was labelled with 99mTc-diethylenetriamine pentaacetic acid (99mTc-DTPA), and on second day, the solid phase was labelled with 99mTc-sulfur colloid in the omelette (Labelling efficiency was 85.3 +/- 3.2%). The studies were carried out by imaging static anterior and posterior views every 20 minutes for a total of 180 minutes. Images were quantified obtaining solid and liquid gastric emptying curves. No statistical significative difference between patients and control subjects gastric emptying results were found. We can conclude that gastric emptying is not a main factor in the pathogenesis of gastroesophageal reflux.