Sinoviortesis con radioisótopos en hemofilia: Experiencia de un centro en Chile / Radionuclide synoviorthesis in hemophilia: experience in 107 patients

Background: In patients with hemophilia, radionuclide synoviorthesis, or the intra-articular injection of a radionuclide to decrease the synovial hypertrophy tissue, aims to decrease or avoid hemarthrosis. Aim: To evaluate the effectiveness of radionuclide synoviorthesis in hemophilia. Material and Methods: Observational retrospective study of the evolution of 107 male patients aged 3 to 54 years who were subjected to radionuclide synoviorthesis between 2007 and 2015. Results: Of 164 treated joints, in 65% treatment was successful, (defined as zero to two hemarthroses and absence of synovitis during the follow up period), in 17% it was partially successful (defined as two or less hemarthroses, but persistence of the synovitis) and failed in 18% of the procedures. No important complications were recorded. Conclusions: Radionuclide synoviorthesis has an overall 82% success rate, is minimally invasive, can be used at any age and is inexpensive We recommend its implementation in Chilean hemophilia treatment centers.

Radionuclide therapy: current status and prospects for internal dosimetry in individualized therapeutic planning

The efficacy and toxicity of radionuclide therapy are believed to be directly related to the radiation doses received by target tissues; however, nuclear medicine therapy continues to be based primarily on the administration of empirical activities to patients and less frequently on the use of internal dosimetry for individual therapeutic planning. This review aimed to critically describe the techniques and clinical evidence of dosimetry as a tool for therapeutic planning and the main limitations to its implementation in clinical practice. The present article is a nonsystematic review of voxel-based dosimetry. Clinical evidence pointing to a correlation between the radiation dose and therapeutic response in various diseases, such as thyroid carcinoma, neuroendocrine tumors and prostate cancer, is reviewed. Its limitations include technical aspects related to image acquisition and processing and the lack of randomized clinical trials demonstrating the impact of dosimetry on patient therapy. A more widespread use of dosimetry in therapeutic planning involves the development of user-friendly dosimetric protocols and confirmation that dose estimation implies good efficacy and low treatment-related toxicity.

Production, quality control, biodistribution assessment and preliminary dose evaluation of [177Lu]-tetra phenyl porphyrin complex as a possible therapeutic agent / Produção, controle de qualidade, avaliação de biodistribuição e avaliação da dose preliminar de [177Lu] -tetra complexo fenil porfirina como um possível agente terapêutico

Due to interesting therapeutic properties of ¹⁷⁷Lu and tumor avidity of tetraphenyl porphyrins (TPPs), ¹⁷⁷Lu-tetraphenyl porphyrin was developed as a possible therapeutic compound. ¹⁷⁷Lu of 2.6-3 GBq/mg specific activity was obtained by irradiation of natural Lu₂O₃sample with thermal neutron flux of 4 × 10¹³ n.cm^-2.s^-1. Tetraphenyl porphyrin was synthetized and labeled with ¹⁷⁷Lu. Radiochemical purity of the complex was studied using Instant thin layer chromatography (ITLC) method. Stability of the complex was checked in final formulation and human serum for 48 h. The biodistribution of the labeled compound in vital organs of wild-type rats was studied up to 7 d. The absorbed dose of each human organ was calculated by medical internal radiation dose (MIRD) method. A detailed comparative pharmacokinetic study was performed for ¹⁷⁷Lu cation and [¹⁷⁷Lu]-TPP. The complex was prepared with a radiochemical purity: >97±1% and specific activity: 970-1000 MBq/mmol. Biodistribution data and dosimetric results showed that all tissues receive approximately an insignificant absorbed dose due to rapid excretion of the complex through the urinary tract. [¹⁷⁷Lu]-TPP can be an interesting tumor targeting agent due to low liver uptake and very low absorbed dose of approximately 0.036 to the total body of human...

Devido às propriedades interessantes do ¹⁷⁷Lu e da avidez tumoral das tetrafenil porfirinas (TPP), desenvolveu-se a ¹⁷⁷Lu-tetrafenil porfirina como composto terapêutico potencial. ¹⁷⁷Lu de atividade específica de 2,6-3 GBq/mg foi obtido por irradiação de amostra de Lu₂O₃ com fluxo térmico de nêutrons de 4 × 10¹³ n.cm^-2.s^-1. Sintetizou-se a tetrafenil porfirina e marcou-se com ¹⁷⁷Lu. A pureza radioquímica do complexo foi estudada usando método de Cromatografia Instantânea de Camada Delgada ( ITLC). A estabilidade do complexo foi checada na formulação final e no ser humano por 48 h. A biodistribuição do composto marcado em órgãos vitais de ratos do tipo selvagem foi estudada por mais de 7 dias. A dose absorvida para cada órgão humano foi calculada pelo método da Dose Médica de Radiação Interna (MIRD). Estudo farmacocinético comparativo detalhado foi efetuado para o cátion ¹⁷⁷Lu e para o [¹⁷⁷Lu]-TPP. O complexo foi preparado com pureza radioquímica >97±1% e atividade específica de 970-1000 MBq/mmol. Os dados de biodistribuição e os resultados dosimétricos mostraram que todos os tecidos receberam uma dose absorvida aproximadamente insignificante devido à rápida excreção do complexo pelo trato urinário. O [¹⁷⁷Lu]-TPP pode ser um agente interessante de direcionamento do tumor devido à baixa captação pelo fígado e pela dose bem baixa absorvida, de, aproximadamente, 0,036 do corpo humano total...

Meningioma de la vaina del nervio óptico: colaterales optociliares y quiste aracnoideo perióptico / Meningioma of the optic nerve sheath: collateral optociliary veins and the perioptic arachnoidal cyst

En la década sesenta, antes del advenimiento de la tomografía computarizada de las órbitas, los meningiomas de la vaina del nervio óptico eran considerados de rara ocurrencia y su diagnóstico positivo solo era posible en aquellos casos en que por su tamaño producían proptosis ocular, la que conducía a su estirpación quirúrgica. El tumor de crecimiento tubular, comprime el nervio en forma progresiva hasta atrofiarlo por completo. Sus manifestaciones clínicas incluyen la pérdida gradual de la agudeza visual hasta alcanzar la ceguera, edema del nervio óptico y luego atrofia del mismo, y presencia de venas colaterales optociliares. Este complejo signológico se designa como triada de Hoyt-Spencer. Un hecho patológico distintivo de estos tumores objetivado mediante resonancia magnética de órbitas con administración de gadolinio y supresión de grasa, es la presencia de una dilatación quística del espacio subaracnoideo perióptico entre el limite distal del tumor y el polo posterior del ojo. Presentamos el caso de un paciente ilustrativo con demostración histopatológica de las colaterales venosas y del quiste aracnoideo

During the 1970s, before the advent of computerized tomography of orbits, optic nerve sheath meningiomas were considered of rare ocurrence and their positive diagnosis was only posible in those cases in which its size produced ocular proptosis, which led to its surgical removal. Tumor growths in a tubular, compreses progressively the optic nerve and in time produces its atrophic thinning. Clinical manifestation include gradual visual acuity loss until total blindness, optic nerve edema and then optic atrophy, and the presence of collateral optociliary veins. This complex clinical picture is designated as the triad of Hoyt-Spencer. A distinctive fact in these tumors is the presence of a cystic dilatation of the perioptic subarachnoid space between the distal adge of the tumor and the posterior pole, which can be defined using magnetic resonance imaging of the orbits with fat supression following intravenous gadolinium administration. We present the case of a patient with histopatological demostration of the collateral veins and the distal aracnoidal cyst

Determinação dos fatores de recuperação do 111In e do 99mTc na quantificação de atividade com imagens SPECT / Determination of 111In and 99mTc recovery in the quantification of activity with SPECT imaging

OBJETIVO: Determinar, experimentalmente, os coeficientes de recuperação do 111In e do 99mTc usando imagens SPECT. MATERIAIS E MÉTODOS: Quatro diferentes concentrações de 111In e de 99mTc foram usadas para quantificar a atividade em esferas de diferentes tamanhos. As imagens foram obtidas com um equipamento híbrido SPECT/CT, com dois detectores. A reconstrução das imagens foi realizada usando o método iterativo ordered subset expectation maximization (OSEM). A correção de atenuação foi realizada com o uso de um mapa de atenuação e a correção de espalhamento foi realizada usando a técnica das janelas de energia. RESULTADOS: Os resultados mostraram que o efeito do volume parcial foi observado de forma mais significativa para as esferas com volume < 6 ml. Para o 111In, os resultados mostram uma dependência com relação às concentrações usadas nas esferas e ao nível de background usado. Para o 99mTc, pôde-se observar uma tendência à subestimação dos resultados quando os níveis mais altos de background foram utilizados. CONCLUSÃO: É necessário usar os fatores de correção para compensar o efeito do volume parcial em objetos com volume < 6 ml para ambos os radionuclídeos. A subtração das contagens espúrias presentes nas imagens SPECT foi o fator que mais influenciou na quantificação da atividade nessas esferas.

OBJECTIVE: To experimentally determine the 99mTc and 111In activity recovery coefficients in SPECT imaging. MATERIALS AND METHODS: Four different 99mTc and 111In concentrations were utilized for quantifying activity in spheres of four different sizes. Images were obtained with a hybrid dual-head SPECT-CT imaging system. The ordered subset expectation maximization (OSEM) iterative method was utilized for images reconstruction. An attenuation map was utilized for attenuation correction, and the multiple energy window technique for scattering correction. RESULTS: Results for spheres < 6 ml in volume were significantly affected by the partial volume effect. For 111In quantification, results show a dependence on sphere concentrations and background levels. For 99mTc quantification, there was a tendency towards values underestimation with higher background levels. CONCLUSION: Correction factors must be utilized for compensating the partial volume effect on objects with < 6 ml in volume for both radionuclides. Background subtraction to compensate spurious count present on SPECT images has a significant influence on the quantification of activity, especially for the smaller objects.

Intracoronary radionuclide therapy with liquid 188Re-filled balloons; radiopharmaceutical and dosimetric studies

Percutaneous transluminal coronary angioplasty associated with radioactive liquid-filled balloons has demostrated to be useful to inhibit the growth of neointimal tissue. The present study pursued optimizing the relation risk/benefit during a procedure of brachytherapy with 188Re associated to angioplasty. Since the possibility of balloon rupture exists, to increase the security during the treatment different agents such as 188Re-DTPA, 188Re-Citrate and 188Re-EC vs 188ReO4 were evaluated. Dosimetric studies using Mirdose 3, after iv injection to Wistar rats, evaluation of a number of safety requirements in order to estimate radiation dose delivered to operating personnel and absorbed doses estimated by Monte Carlo method (PENELOPE). It is a safe procedure, both for the patient and the working staff; in case of ballon rupture the use of the above mentioned radiopharmaceuticals increases its security. 188Re beta emitor achieves a local dosis, diminishing the dose in healthy tissue.

High-dose-rate interstitial brachytherapy in the management of carcinoma of the uterine cervix and other gynecologic malignancies.

OBJECTIVE: To report technique and experience of high-dose-rate (HDR) interstitial brachytherapy in the treatment of cervical carcinoma and other gynecologic malignancies. MATERIAL AND METHOD: Between April 2003 and October 2004, ten patients (7-cervical carcinoma, 3-vaginal stump carcinoma) were treated with interstitial implant. Indications for implant include previous hysterectomy and previous pelvic radiation. Patient characteristics, implant technique, and initial outcomes were reported. RESULTS: Transperineal interstitial implant was performed using fluoroscopy-guided technique. Brachytherapy dose/fraction ranged from 500-750 cGy for 1 to 6 fractions. Combined external beam radiation was given in 8 patients. After 5-21 months follow-up, all the patients were alive. Local control was achieved in 9 patients. One patient had persistent disease at the implant site. No acute complication from the procedure or serious late complication was observed. CONCLUSION: Interstitial implant can be a treatment option in patients with gynecologic malignancies who have limitations with standard intracavitary insertion. This technique is feasible, providing good local control without serious complications. However, long-term follow-up is needed.

Protocolos de estudio de perfusión miocárdica con radioisotopos en evaluación de cardiopatía coronaria / Studies of myocardial perfusion using radioisotopes in the coronary heart disease

Se revisan los principales protocolos actuales de perfusión miocárdica con técnica isotópica, sus indicaciones, requerimientos y nuevas aplicaciones. Se da especial énfasis a la técnica de SPECT gatillado que agrega parámetros de función a las imágenes tomográficas con mayor valor diagnóstico y pronóstico y también a la introducción de positrones mediante fluordeoxiglucosa en la detección de viabilidad miocárdica.

Intercomparação e calibração de medidores de atividade utilizados em serviços de medicina nuclear / Intercomparison and calibration of dose calibrators used in nuclear medicine facilities

OBJETIVO: O objetivo deste trabalho foi estabelecer um padrão de trabalho para intercomparação e calibração de medidores de atividade (calibradores de dose) utilizados na maioria dos serviços de medicina nuclear, para determinação da atividade dos radionuclídeos administrados aos pacientes nos exames específicos ou nos procedimentos terapêuticos. MATERIAIS E MÉTODOS: Foi utilizado um calibrador de dose comercial, um conjunto de fontes radioativas padrões, além de seringas, frascos e ampolas contendo soluções de radionuclídeos utilizados em medicina nuclear. RESULTADOS: O calibrador de dose comercial foi calibrado com soluções de radionuclídeos utilizados em medicina nuclear. Os testes simples do instrumento, tais como o teste de linearidade e da variação da resposta com o volume da fonte a uma concentração de atividade constante, foram descritos e realizados. CONCLUSÃO: O instrumento estudado pode agora ser utilizado como sistema de referência para intercomparação e calibração de outros instrumentos medidores de atividade, como um método de controle da qualidade de calibradores de dose utilizados em serviços de medicina nuclear.

OBJECTIVE: The aim of this work was to establish a working standard for intercomparison and calibration of dose calibrators used in most of nuclear medicine facilities for the determination of the activity of radionuclides administered to patients in specific examinations or therapeutic procedures. MATERIALS AND METHODS: A commercial dose calibrator, a set of standard radioactive sources, and syringes, vials and ampoules with radionuclide solutions used in nuclear medicine were utilized in this work. RESULTS: The commercial dose calibrator was calibrated for radionuclide solutions used in nuclear medicine. Simple instrument tests, such as linearity response and variation response with the source volume at a constant source activity concentration were performed. CONCLUSION: This instrument may be used as a reference system for intercomparison and calibration of other activity meters, as a method of quality control of dose calibrators utilized in nuclear medicine facilities

Intravascular brachytherapy: a model for the calculation of the dose

In this study we present the radiation dose distribution for a theoretical model with Montecarlo simulation, and based on an experimental model developed for the study of the prevention of restenosis post-angioplasty employing intravascular brachytherapy. In the experimental in vivo model, the atherosclerotic plaques were induced in femoral arteries of male New Zealand rabbits through surgical intervention and later administration of cholesterol enriched diet. For the intravascular irradiation we employed a 32P source contained within the balloon used for the angioplasty. The radiation dose distributions were calculated using the Monte Carlo code MCNP4B according to a segment of a simulated artery. We studied the radiation dose distribution in the axial and radial directions for different thickness of the atherosclerotic plaques. The results will be correlated with the biologic effects observed by means of histological analysis of the irradiated arteries

Dosimetria interna de radioinmunoterapia: consideraciones generales / Radioimmunotherapy internal dosimetry: general considerations

La Radioinmunoterapia ha atraído rápidamente el interés como modalidad potencial en el tratamiento del cáncer. Este presente trabajo revisa varios aspectos dosimétricos que involucran la efectividad de la técnica, así como, los procedimientos empleados en la obtención de la información dosimétrica, el tipo de radionucleido seleccionado, las limitaciones y posibilidades de los métodos de estimación dosimétrica; y proporciona un estudio detallado sobre los modelos radiobiológicos que con potencialidad pueden ser utilizados en la prescripción de la dosis en un sistema de planificación que permita establecer una relación dosis/respuesta del tratamiento

Pruebas diagnósticas de medicina nuclear / The diagnostic tests in nuclear medicine

La autora ofrece un detalle de las pruebas diagnósticas de Medicina Nuclear más frecuentes en la actualidad, consignando la preparación requerida del paciente y la duración aproximada del procedimiento. El artículo subraya la inocuidad del uso de radioisótopos para estudios diagnósticos en el aspecto de la bioseguridad del personal de enfermería

Gammagrafía ósea en pediatría / Bone scintigraphy in children

Es de vital importancia establecer el diagnóstico temprano de enfermedad ósea en el niño a fin de evitar alteraciones en el crecimiento y desarrollo. Uno de los métodos que por su sensibilidad ha favorecido el diagnóstico temprano es la gammagrafía ósea. En el INP esta técnica se ha realizado en los últimos 25 años. Presentamos nuestra experiencia como aporte al conocimiento de la patología pediátrica. Se describen las bases fisiológicas y fisiopatológicas de la gammagrafía ósea, su aplicación, limitaciones y datos gammagráficos que se observan en la patología tumoral, infecciosa y vascular

Predicción del VEF1 postoperatorio en el paciente que va a ser sometido a resección pulmonar a través de estudio de perfusión pulmonar con radionúclidos

Se realizó un estudio descriptivo donde se analizaron 19 pacientes sometidos a resección pulmonar por patología pulmonar y a quienes se les practicó un estudio de perfusión pulmonar en Medicina Nuclear y se les calculó el VEF1 (volumen respiratorio forzado al primer segundo) con el que iban a quedar después de la cirugía. Se realizó un análisis de regresión lineal y se calculó el coeficiente R de correlacción entre el valor predicho por Medicina Nuclear y el valor real, tomando de la espitometría al mes de la cirugía; se encontró una R de 0.97 y una sensibilidad de 95 por ciento.

Braquiterapia de alta taxa de dose / High dose rate brachytherapy

A braquiterapia de alta taxa de dose utiliza fonte unica de '192 ANT. IND Ir' com atividade nominal inicial de 10Ci em equipamento com controle remoto. Esta tecnica permite que o tratamento seja realizado em regime ambulatorial, sem os inconvenientes da braquiterapia classica, como anestesia geral ou raquidiana, imobilizacao prolongada no leito e exposicao de pessoa a irradiacao. O servico de radioterapia possui cinco protocolos de tratamento em estudo: carcinoma de colo uterino, endometrio, pulmao, esofago e tumores do sistema nervoso central. Desde a instalacao do Micro Selectron HDR foram tratados 90 pacientes, com um total de 257 procedimentos. As aplicacoes sao semanais, perfazendo tres a quatro fracoes. Devido ao pouco tempo de atividade, os resultados sao preliminares, mas perfeitamente comparaveis aos primeiros meses dos tratamenos classicos. Nao tivemos nenhuma complicacao durante os procedimentos ou imediatamente apos. Muitos estudos devem ser realizados para se estabelecer criterios de dose, fracionamento e associacao ideais, a fim de se alcancar um alto nivel de taxa terapeutica.

Antibody mediated targeting of radioisotopes, drugs and toxins in diagnosis and treatment.

The recent resurgence of interest in site specific delivery of radioisotopes, chemotherapeutic drugs and toxins for the diagnosis and treatment of cancer, and for the selective manipulation of the immune system, can be directly related to the need for improved diagnosis and the fact that for many cancers, for example lung, colon and gastric, the conventional treatments of surgery, radiotherapy and chemotherapy have reached a plateau in terms of the number of patients cured. To date, because of their specificity, the major emphasis has been on the use of antibodies as carriers and extensive in vitro, in vivo preclinical and clinical evaluation is underway. The aim of this article is to review recent progress, highlight avenues being explored to overcome limitations and to indicate new approaches that are evolving in antibody mediated targeting.

La centelleografía pulmonar mediante la inhalación de aerosoles radiactivos monodispersos: informe preliminar / Lung scintigraphy by the use of radioactive monodisperse aerosols: preliminary report

Este artículo describe un método para la centelleografía inhalatoria pulmonar (CIP), mediante el uso de aerosoles radiactivos monodispersos con partículas menores de 2 micronm de diámetro, y los hallazgos comunes en sujetos normales, en pacientes con embolias pulmonares (EP) y/o enfermedad obstructiva pulmonar (EOP), y en individuos con hipertensión pulmonar exagerada. Este procedimiento posee numerosas ventajas sobre el empleo de los gases radiactivos como el 133 Xe y el 81 Kr: costo menor, mayor sencillez, proyecciones centelleográficas múltiples en un solo estudio, logro de las imágenes perfusorias y ventilatorias en una sola sesión, y obtención de imágenes inhalatorias y perfusorias con resolución espacial idéntica y con densidad de datos similar. Se concluye que la CIP con aerosoles radiactivos monodispersos, en un método útil para el estudio de la EOP y un auxiliar importante de la centelleografía perfusoria pulmonar en el diagnóstico de las EP