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PURPOSE: To evaluate morphological and signal intensity (SI) changes of placental insufficiency on magnetic resonance imaging (MRI) and to assess morphological changes and decreased flow voids (FVs) on T2-weighted rapid acquisition with relaxation enhancement (RARE) images for diagnosing placental insufficiency. METHODS: Fifty singleton fetuses underwent MRI using a 1.5-T MR scanner. Placental thickness, area, volume, SI, amniotic fluid SI, and size of FVs between the uterus and the placenta were measured on MR images. Two radiologists reviewed T2-weighted RARE images for globular appearance of the placenta and FVs between the uterus and the placenta. Data were analyzed using t-tests, McNemar's tests, and areas under the receiver operating characteristic curve (AUCs) at 5% level of significance. RESULTS: Twenty-five of the 50 pregnancies were categorized as having an insufficient placenta. Significant differences were observed between insufficient and normal placentas in mean placental thickness, area, volume, placenta to amniotic fluid SI ratio, and size of FVs (49.0 mm vs. 36.9 mm, 1.62 × 10(4) mm(2) vs. 2.67 × 10(4) mm(2), 5.13 × 10(5) mm(3) vs. 6.56 × 10(5) mm(3), 0.549 vs. 0.685, and 3.4 mm vs. 4.3 mm, respectively). The sensitivity and accuracy using globular appearance plus decreased FVs were greater than those using decreased FVs (P < 0.01). There was no significant difference among AUCs using globular appearance and decreased FVs, and globular appearance plus decreased FVs. CONCLUSIONS: Placental insufficiency was associated with placental thickness, area, volume, placenta to amniotic fluid SI ratio, and size of FVs. Evaluating FVs on T2-weighted RARE images can be useful for detecting placental insufficiency, particularly in placentas without globular appearance on MR images.
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Feto/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Insuficiencia Placentaria/diagnóstico por imagen , Femenino , Humanos , EmbarazoRESUMEN
Magnetic resonance imaging (MRI) of the breast has become important not only for assessing the extent of breast cancer for breast-conserving surgery but also for the evaluation and diagnosis of other benign and malignant pathologies. We radiologists therefore need to know the appropriate indications for performing breast MRI and understand the MRI features of breast disease. We herein review and discuss the application of current pulse sequences and the imaging strategies for MRI of breast pathologies. We will illustrate the MRI features of various breast pathologies including malignant tumors such as invasive and noninvasive ductal carcinoma, special types of invasive carcinoma (mucinous, apocrine, lobular carcinoma, spindle cell carcinoma, and so on), inflammatory carcinoma, semimalignant tumor (phyllodes tumor), benign tumors (fibroadenoma, intraductal and intracystic papilloma), inflammatory conditions, and postsurgical changes. We will also demonstrate three-dimensional fusion images of MR ductography and breast MRI of patients with nipple discharge.
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Enfermedades de la Mama/diagnóstico , Imagen por Resonancia Magnética , Neoplasias de la Mama/diagnóstico , Femenino , HumanosRESUMEN
Nipple discharge is a common symptom that mostly results from benign conditions. The most significant cause is carcinoma, which accounts for 1%-45% of cases. Therefore, identification of intraductal lesions is important. Conventional ductography, the recommended method of identifying lesions, is invasive and has inherent limitations. Magnetic resonance (MR) ductography is performed with heavily T2-weighted sequences; it is noninvasive and requires neither radiation nor contrast media. Like conventional ductography, MR ductography shows the dilated ducts as tubular structures with high signal intensity. Intraductal lesions appear as a signal defect, duct wall irregularity, or ductal obstruction. No specific conventional ductographic or MR ductographic finding allows differentiation between benign and malignant disease, and neither technique can demonstrate the extent of disease. MR mammography with intravenous injection of contrast material reveals the extent of disease, and a dynamic study may help distinguish between malignant and benign lesions. Fusion imaging with MR ductography and MR mammography demonstrates not only the presence of an intraductal abnormality but also the extent of the lesion on one image, thus clearly showing the relationship between the dilated duct and the intraductal lesion.
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Enfermedades de la Mama/diagnóstico , Neoplasias de la Mama/diagnóstico , Imagen por Resonancia Magnética , Glándulas Mamarias Humanas/patología , Mamografía/métodos , Pezones , Adulto , Anciano , Femenino , Humanos , Persona de Mediana EdadRESUMEN
OBJECTIVE: The purpose of our study was to assess the usefulness of dynamic MRI in distinguishing high-flow vascular malformations from low-flow vascular malformations, which do not need angiography for treatment. SUBJECTS AND METHODS: Between September 2001 and January 2003, 16 patients who underwent conventional and dynamic MRI had peripheral vascular malformations (six high- and 10 low-flow). The temporal resolution of dynamic MRI was 5 sec. Time intervals between beginning of enhancement of an arterial branch in the vicinity of a lesion in the same slice and the onset of enhancement in the lesion were calculated. We defined these time intervals as "artery-lesion enhancement time." Time intervals between the onset of enhancement in the lesion and the time of the maximal percentage of enhancement above baseline of the lesion within 120 sec were measured. We defined these time intervals as "contrast rise time" of the lesion. Diagnosis of the peripheral vascular malformations was based on angiographic or venographic findings. RESULTS: The mean artery-lesion enhancement time of the high-flow vascular malformations (3.3 sec [range, 0-5 sec]) was significantly shorter than that of the low-flow vascular malformations (8.8 sec [range, 0-20 sec]) (Mann-Whitney test, p < 0.05). The mean maximal lesion enhancement time of the high-flow vascular malformations (5.8 sec [range, 5-10 sec]) was significantly shorter than that of the low-flow vascular malformations (88.4 sec [range, 50-100 sec]) (Mann-Whitney test, p < 0.01). CONCLUSION: Dynamic MRI is useful for distinguishing high-flow from low-flow vascular malformations, especially when the contrast rise time of the lesion is measured.
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Malformaciones Arteriovenosas/diagnóstico , Imagen por Resonancia Magnética/métodos , Enfermedades Vasculares Periféricas/diagnóstico , Adolescente , Adulto , Angiografía , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Estudios Prospectivos , Estadísticas no ParamétricasRESUMEN
PURPOSE: To evaluate the effect of Joint Photographic Experts Group (JPEG) compression ratios of 10:1 and 20:1 on detection of acute cerebral infarction at computed tomography (CT). MATERIALS AND METHODS: CT images obtained in 25 patients with acute cerebral infarction and 25 patients with no lesions were compressed by means of a JPEG algorithm at ratios of 10:1 and 20:1. Normal and abnormal sections (on original and compressed images) were reviewed by using a color soft-copy computed monochrome cathode ray tube monitor. Five observers rated the presence or absence of a lesion with a 50-point scale (0, definitely absent; 25, equivocal; and 50, definitely present). Diagnostic accuracy was evaluated with receiver operating characteristic (ROC) curve analysis. Significant difference was defined as a P value less than.05 for the area tested with a two-tailed paired Student t test. RESULTS: At ROC analysis, no statistically significant difference was detected for all cases considered together (Az [area under the ROC curve] = 0.887 +/- 0.038 [mean +/- SD] on noncompressed images, Az = 0.897 +/- 0.038 on 10:1 compressed images, and Az = 0.842 +/- 0.073 on 20:1 compressed images; P >.05). CONCLUSION: JPEG compression at ratios of 10:1 and 20:1 was tolerated in the detection of acute cerebral infarction at CT.
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Infarto Cerebral/diagnóstico por imagen , Procesamiento de Imagen Asistido por Computador , Tomografía Computarizada por Rayos X , Enfermedad Aguda , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
PURPOSE: The purpose of this study was to evaluate the extent of pseudoenhancement in a phantom model using three different CT scanners. METHODS: The phantom consisted of a water-filled balloon (cyst) suspended in varying concentrations of iodine solution, meant to simulate varying levels of renal enhancement. The phantom was scanned with single detector-row CT scanners of three different manufacturers. All scans were performed at 120 kV and 200 mA with 5 mm collimation. RESULTS: The degree of pseudoenhancement differed among the three scanners. In two of the scanners, the attenuation of water in the balloon (cyst) was noted to increase significantly as the iodine concentration in the cylinder was increased. However, the degree of pseudoenhancement was different between the two scanners. In the other scanner, attenuation of the cyst was noted to decrease as the iodine concentration in the cylinder decreased and to increase as the iodine concentration in the cylinder increased. CONCLUSION: The degree of pseudoenhancement may vary in scanners of different manufacturers. We may need to check the pattern and degree of pseudoenhancement in CT scanners before determining the enhancement threshold for simple renal cyst.