RESUMEN
Fast scan magnetic resonance imaging techniques for adipose tissue (AT) quantification were compared to a conventional T1-weighted spin-echo (SE) sequence (TR = 500 ms, TE = 20 ms), imaging a mid-abdominal slice. A rapid T1-weighted SE sequence (TR = 36 ms, TE = 14 ms) was optimal, with minimal distortion (field, motion, flow artefact). Tissue contrast was higher and visceral AT was clearly differentiated. Quantification of all AT compartments (total, subcutaneous, internal, visceral) showed close agreement with the T1-weighted SE sequence and reproducibility was high (coefficient of variation < 4.7%). For AT quantification in a whole subject, this fast technique allows each image to be acquired serially at the magnet isocenter, as the subject is moved through the scanner (serial isocenter scanning, SIS). This method provides minimal image distortion and allows rapid coverage of the whole body.
Asunto(s)
Tejido Adiposo/anatomía & histología , Imagen por Resonancia Magnética/métodos , Abdomen/anatomía & histología , Composición Corporal , Estudios de Factibilidad , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Reproducibilidad de los ResultadosRESUMEN
We describe two methods of breast immobilization using the lateral decubitus position to increase patient comfort and access to the axillary tail for MR-guided biopsy in the postsurgical or irradiated breast. The first method uses a compression device with good immobilization but poor patient tolerance. The second approach uses a thermoplastic mesh material to form a rigid exoskeleton around the breast: immobilization is adequate and patient acceptability is good. The latter method is preferred and requires formal evaluation in larger scale trials.
Asunto(s)
Biopsia con Aguja , Neoplasias de la Mama/patología , Imagen por Resonancia Magnética , Radiología Intervencionista , Biopsia con Aguja/instrumentación , Neoplasias de la Mama/diagnóstico , Neoplasias de la Mama/radioterapia , Neoplasias de la Mama/cirugía , Diseño de Equipo , Femenino , Humanos , Inmovilización , Imagen por Resonancia Magnética/instrumentación , Imagen por Resonancia Magnética/métodos , Mastectomía Segmentaria , Sensibilidad y EspecificidadRESUMEN
Eighteen term infants with hypoxic ischaemic encephalopathy (HIE) were studied with serial magnetic resonance imaging of the brain for up to two months following birth. Important early findings included brain swelling, cortical highlighting, diffuse loss of grey/white differentiation and loss of signal in the posterior limb of the internal capsule (PLIC). These signs were easier to identify on T1-weighted spin echo or inversion recovery sequences than on T2-weighted spin echo sequences. Brain swelling was only seen in the first seven days and was present in all grades of HIE. All other signs persisted and were associated with the subsequent development of major structural changes in the brain. The exact pattern of injury was best identified after the first week of life once the signs of brain swelling had cleared.
Asunto(s)
Isquemia Encefálica/complicaciones , Isquemia Encefálica/fisiopatología , Lóbulo Frontal/fisiopatología , Hipoxia/complicaciones , Hipoxia/fisiopatología , Lóbulo Occipital/fisiopatología , Asfixia Neonatal/etiología , Asfixia Neonatal/fisiopatología , Ganglios Basales/fisiopatología , Ventrículos Cerebrales/anomalías , Hipocampo/fisiopatología , Humanos , Recién Nacido , Imagen por Resonancia Magnética , Índice de Severidad de la Enfermedad , Tálamo/fisiopatologíaRESUMEN
The potential value of magnetic resonance imaging as a diagnostic tool in infertility was investigated. Twenty-six women with primary or secondary infertility and symptoms of dysmenorrhoea or menorrhagia were studied prospectively using conventional T1- and T2-weighted spin-echo techniques. Positive diagnoses were obtained in 20 of 26 (76.9%) patients. Of these, 18 (69.2%) had lesions likely to be significantly contributing to infertility. Adenomyosis was detected in 14 patients (53.8%) with 11 showing the diffuse pattern while three had discrete adenomyomas. Cystic lesions typical of endometriosis were detected in seven patients (26.9%), four of these also had evidence of adenomyosis. The endometriotic lesions were also seen at laparoscopy in each case. Five patients (19.2%) had leiomyomas, one in a patient with adenomyosis and endometriosis and one in a patient with endometriosis alone. Only one patient had submucous leiomyomas causing significant distortion of the endometrial mucosa likely to affect fertility. Magnetic resonance imaging is valuable in the investigation of unexplained infertility where it provides a high diagnostic yield particularly if uterine pathology is suspected.
Asunto(s)
Infertilidad Femenina/etiología , Imagen por Resonancia Magnética , Adulto , Dismenorrea/etiología , Dismenorrea/patología , Femenino , Humanos , Infertilidad Femenina/patología , Leiomioma/complicaciones , Leiomioma/patología , Menorragia/complicaciones , Menorragia/etiología , Menorragia/patología , Neoplasias Ováricas/complicaciones , Neoplasias Ováricas/patología , Estudios Prospectivos , Neoplasias Uterinas/complicaciones , Neoplasias Uterinas/patologíaRESUMEN
OBJECTIVE: The purpose of this study was to characterize the normal zonal anatomy and vascularity of the cervix on in vivo and in vitro MR images obtained with a receiver coil surrounding the cervix. These appearances provide a normal data base from which to interpret subtle changes in early neoplasia. SUBJECTS AND METHODS: Thirteen women of reproductive age with clinically and cytologically normal cervices were imaged with a ring-design solenoid receiver coil that was placed intravaginally and enveloped the cervix. T1- and T2-weighted axial images were obtained. Seven uterine specimens resected for benign disease were similarly studied, and imaging appearances were correlated with histologic findings. RESULTS: In the in vivo studies, the endocervical mucosa and two stromal zones surrounding the high-signal central canal were identified. Unlike the uterine body, they could be differentiated on both T1- and T2-weighted images, on which the inner ring had a low signal and the outer ring had an intermediate signal intensity. The outer zone was highly vascularized, with inflow effects from large vessels visible on single-slice scans. On administration of gadopentetate dimeglumine, the endocervical mucosa enhanced rapidly, whereas the outer stroma showed more gradual enhancement. The inner zone enhanced slowly relative to the outer zone. The parametrium was visualized up to 6 cm from the center of the coil, and adjacent colon, fat, and blood vessels were identified. Up to four lymph nodes less than 1 cm in diameter were seen in the parametrium of three subjects. In the in vitro studies, the endocervical mucosa was of high signal intensity. In the fibromuscular cervix, an inner low-signal ring correlated with a region of tightly packed stroma (fibroblasts and smooth muscle cells; cell count, 5900 +/- 2376 nuclei/mm2) and the intermediate-signal-intensity outer zone corresponded to a region of more loosely packed stroma (cell count, 2199 +/- 558 nuclei/mm2). Retention cysts were present in two multiparous cervices. CONCLUSION: These detailed appearances and enhancement patterns of the normal cervix need to be recognized so that subtle changes in locally invasive cervical neoplasia can be identified.
Asunto(s)
Cuello del Útero/anatomía & histología , Imagen por Resonancia Magnética/instrumentación , Adulto , Medios de Contraste , Combinación de Medicamentos , Femenino , Gadolinio , Gadolinio DTPA , Humanos , Imagen por Resonancia Magnética/métodos , Meglumina , Compuestos Organometálicos , Paridad , Ácido Pentético/análogos & derivados , Valores de ReferenciaRESUMEN
To assess the effect of stimulus correlated motion on the appearance of functional magnetic resonance images, conventional visual and motor protocols were each performed by four normal volunteers and an image co-registration technique was used to retrospectively monitor subject motion. In three studies synthetic data sets were constructed from single baseline images using the positional information obtained from the co-registration procedure. Cumulative difference images were then created from both the synthetic and functional image sets. Stimulus correlated motion was detected in all eight studies and the synthetic cumulative difference images showed striking similarities to the equivalent functional images in each case.