Dosimetría en tomografía computada / Dosimetry in computed tomography

La cantidad de estudios de tomografía computada (TC) que se llevan a cabo por año en el mundo crece de manera exponencial, fundamentalmente por la incorporación de la tomografía computada multicorte (TCMC) que permite la realización de estudios en pocos segundos. Sin embargo, a pesar del beneficio diagnóstico que tienen los pacientes, la dosis de radiación recibida con este tipo de prácticas es una preocupación en la comunidad profesional, debido a que es necesario disminuirla tanto como sea razonablemente posible. El presente artículo describe las principales unidades dosimétricas utilizadas en la tomografía computada, con el fin de poder trabajar con ellas de manera sencilla, utilizando los valores de los equipos modernos y los de referencia conocidos internacionalmente...

[Diagnosis and treatment of myasthenia gravis. Experience 1974-1992]. / Diagnostico y tratamiento de la myasthenia gravis. Experiencia 1974-1992.

Between 1974 and 1992, 118 patients with Myasthenia gravis (MG) were studied in our Hospital; 92 patients, followed up for longer than 6 months, were surveyed for therapeutical results. Patients were categorized according to Osserman criteria; 22 belonged to group I; 77 to group II; 4 to group III and 15 to group IV. MG predominated in females, the ratio was 1.87:1.0. This predominance was more obvious in patients below 35 years of age (2.68:1.0) than above (1.18:1.0). The greatest prevalence was found at the 3rd decade of life. The assessment of the diagnostic test is as follows: 1) edrophonium test was positive in 97% of 93 patients; 2) supramaximal repetitive stimulation performed in 3 different nerves yielded positive results in 83% of 118 patients. It is worth noting that the test was positive in 92% of patients with generalized MG while only 48% of those with ocular MG displayed positive results; 3) sera antiacetycholine receptor antibodies (ACRA) quantification produced positive results in 88% of the patients with generalized MG and in 33% of ocular MG. Altogether the positivity of this test was 83%; 4) passive transfer of patients sera (25 generalized and 2 ocular MG forms) to mice and measurement of mepp's amplitude in the phrenic-diaphragm in vitro preparation yielded positive results in 100% of the tested cases. Once the diagnosis was achieved, the characteristics of the thymus were studied combining pneumomediastinography and linear tomography (PT) in 60 patients. Thorax Computed tomography (CT) was performed in 51 patients. Of those patients who underwent thymectomy, the coherence between radiological and histological diagnosis for PT was 100% while for CT just 60%. More recently 14 patients were studied by combining both procedures. Reliability of this technique is currently under study. Therapeutical assessment was carried out adscribing patients to 5 different groups according to their response after treatment withdrawal; group 2: Improved, neither symptoms nor signs; group 1: Remission, neither symptoms nor signs while on medication or minimal disability without medication; group 3: Unchanged while on medication; group 4: Worse, patients with more severe or frequent signs and symptoms despite being on treatment, group 5: Death, patients who died due to respiratory failure. Groups 1 and 2 were considered successful while 3, 4 and 5 as unsuccessful. Treatment was based on the administration of anticholinesterase drugs (piridostigmine, neostigmine) in 113 patients. Of these, 35 received those drugs as the only medication of whom 39% obtained successful results. Steroids (methylprednisone) were administered to 75 patients, in 40 cases combined with anticholinesterase drugs.(ABSTRACT TRUNCATED AT 400 WORDS)

Diagnostico y tratamiento de la myasthenia gravis. Experiencia 1974-1992. / [Diagnosis and treatment of myasthenia gravis. Experience 1974-1992]

Between 1974 and 1992, 118 patients with Myasthenia gravis (MG) were studied in our Hospital; 92 patients, followed up for longer than 6 months, were surveyed for therapeutical results. Patients were categorized according to Osserman criteria; 22 belonged to group I; 77 to group II; 4 to group III and 15 to group IV. MG predominated in females, the ratio was 1.87:1.0. This predominance was more obvious in patients below 35 years of age (2.68:1.0) than above (1.18:1.0). The greatest prevalence was found at the 3rd decade of life. The assessment of the diagnostic test is as follows: 1) edrophonium test was positive in 97

of 93 patients; 2) supramaximal repetitive stimulation performed in 3 different nerves yielded positive results in 83

of 118 patients. It is worth noting that the test was positive in 92

of patients with generalized MG while only 48

of those with ocular MG displayed positive results; 3) sera antiacetycholine receptor antibodies (ACRA) quantification produced positive results in 88

of the patients with generalized MG and in 33

of ocular MG. Altogether the positivity of this test was 83

; 4) passive transfer of patients sera (25 generalized and 2 ocular MG forms) to mice and measurement of mepps amplitude in the phrenic-diaphragm in vitro preparation yielded positive results in 100

of the tested cases. Once the diagnosis was achieved, the characteristics of the thymus were studied combining pneumomediastinography and linear tomography (PT) in 60 patients. Thorax Computed tomography (CT) was performed in 51 patients. Of those patients who underwent thymectomy, the coherence between radiological and histological diagnosis for PT was 100

while for CT just 60

. More recently 14 patients were studied by combining both procedures. Reliability of this technique is currently under study. Therapeutical assessment was carried out adscribing patients to 5 different groups according to their response after treatment withdrawal; group 2: Improved, neither symptoms nor signs; group 1: Remission, neither symptoms nor signs while on medication or minimal disability without medication; group 3: Unchanged while on medication; group 4: Worse, patients with more severe or frequent signs and symptoms despite being on treatment, group 5: Death, patients who died due to respiratory failure. Groups 1 and 2 were considered successful while 3, 4 and 5 as unsuccessful. Treatment was based on the administration of anticholinesterase drugs (piridostigmine, neostigmine) in 113 patients. Of these, 35 received those drugs as the only medication of whom 39

obtained successful results. Steroids (methylprednisone) were administered to 75 patients, in 40 cases combined with anticholinesterase drugs.(ABSTRACT TRUNCATED AT 400 WORDS)