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At least 703 records · Page 39Linked to original sources
PubMed1992

Magnetic resonance imaging to monitor pathology of caudate-putamen after excitotoxin-induced neuronal loss in the nonhuman primate brain.

We used MR imaging to locate and monitor in vivo the pathological events taking place 2 to 4 weeks after unilateral striatal injections of ibotenic acid (IA) in the Papio papio baboon. As early as 2 weeks after IA injections, excitotoxic lesions in the caudate and the putamen were directly visualized on T1-weighted images as small areas of low signal intensity. On T2-weighted images, the lesion sites were visualized as areas of high-intensity signal, spreading over larger areas than the corresponding regions in T1-weighted images. These alterations of T2-values in the lesioned striatum persisted 4 weeks after surgery. However, as the striatal degeneration progressed from 2 to 4 weeks after lesion, the size of the areas of high signal intensity on T2-weighted images decreased, whereas the same regions appeared essentially unmodified on T1-weighted images. A marked enlargement of the ipsilateral lateral ventricle (a characteristic of excitotoxic striatal lesions) could be detected 4 weeks after surgery, on both axial T1- and T2-weighted images. Comparisons of MR images with postmortem anatomical data indicated that areas of increased T1 values corresponded to regions of severe neuronal depletion (a direct result of the excitotoxic lesion), whereas areas of increased T2 values corresponded to regions of increased content in astrocytes and ferritin and probably in the early period following lesion (2 weeks) to a superimposed edema.

Animals↗
PubMed2006

Dense deformation field estimation for atlas-based segmentation of pathological MR brain images.

Atlas registration is a recognized paradigm for the automatic segmentation of normal MR brain images. Unfortunately, atlas-based segmentation has been of limited use in presence of large space-occupying lesions. In fact, brain deformations induced by such lesions are added to normal anatomical variability and they may dramatically shift and deform anatomically or functionally important brain structures. In this work, we chose to focus on the problem of inter-subject registration of MR images with large tumors, inducing a significant shift of surrounding anatomical structures. First, a brief survey of the existing methods that have been proposed to deal with this problem is presented. This introduces the discussion about the requirements and desirable properties that we consider necessary to be fulfilled by a registration method in this context: To have a dense and smooth deformation field and a model of lesion growth, to model different deformability for some structures, to introduce more prior knowledge, and to use voxel-based features with a similarity measure robust to intensity differences. In a second part of this work, we propose a new approach that overcomes some of the main limitations of the existing techniques while complying with most of the desired requirements above. Our algorithm combines the mathematical framework for computing a variational flow proposed by Hermosillo et al. [G. Hermosillo, C. Chefd'Hotel, O. Faugeras, A variational approach to multi-modal image matching, Tech. Rep., INRIA (February 2001).] with the radial lesion growth pattern presented by Bach et al. [M. Bach Cuadra, C. Pollo, A. Bardera, O. Cuisenaire, J.-G. Villemure, J.-Ph. Thiran, Atlas-based segmentation of pathological MR brain images using a model of lesion growth, IEEE Trans. Med. Imag. 23 (10) (2004) 1301-1314.]. Results on patients with a meningioma are visually assessed and compared to those obtained with the most similar method from the state-of-the-art.

Brain↗
PubMedDate not supplied

Dentate nuclei involvement in AIDS patients with CNS cryptococcosis: imaging findings with pathologic correlation.

PURPOSE: Our goal was to describe the involvement of the dentate nuclei in AIDS patients with CNS cryptococcosis since this finding has not been emphasized in previous radiological literature. METHOD: Plain and contrast-enhanced CT of the brain (10 and 10), MR studies (1 premortem and 1 postmortem), and autopsy findings in 11 AIDS patients with CNS cryptococcosis were reviewed. The imaging studies and pathological specimens were analyzed for signs of meningitis, presence of dilated Virchow-Robin spaces, gelatinous pseudocysts, cryptococcoma, ventriculomegaly, choroid plexus, and ependymal lesions. RESULTS: Five of 11 patients were found at autopsy to have macroscopically visible "cystic" lesions in the dentate nuclei that were not detected on CT (10 patients), but were seen on premortem MR (1 patient). Macroscopic supratentorial (basal ganglia, thalamic, midbrain) lesions were detected by CT in 5 of 11 patients and by MR in 2 of 2 patients. Enhancement of the leptomeninges was seen in only 1 patient by CT despite pathological evidence of cryptococcal meningitis in all 11 patients. Dilated Virchow-Robin spaces were seen in all 11 pathologic specimens and in the 2 MR studies but not on CT. Communicating hydrocephalus was detected by CT in two patients. CONCLUSION: CT scans of the brain underestimate infratentorial parenchymal cryptococcal disease. MR is a more sensitive procedure to evaluate cerebellar and brainstem cryptococcosis, including the dentate nuclei, which in our autopsy series was not an uncommon site to be infected with cryptococcal gelatinous pseudocysts.

AIDS-Related Opportunistic Infections↗
PubMed2004

Primary brachial plexus tumors: imaging, surgical, and pathological findings in 25 patients.

OBJECT: The authors report on the treatment of primary brachial plexus tumors in 25 patients at the University of California, San Francisco. They compare their findings with those obtained in similar series. METHODS: The authors reviewed the electronic and medical records, radiological images, operative reports, and pathological findings in 25 consecutive cases of primary brachial plexus tumors. Cases of metastatic lesions or adjacent neoplasms extending into and involving the brachial plexus were excluded. At presentation patients ranged in age from 19 to 71 years (mean 47-15 years), and neurofibromatosis was present in eight patients (32%). Presenting signs and symptoms included palpable mass (60%), numbness/paresthesias (44%), radiating pain (44%), local pain (16%), and weakness (12%). Duration of symptoms ranged from 2 months to 10 years. Neuroimaging revealed lesions ranging widely in size (volume approximately 1 to 100 ml). Pathological diagnoses included schwannoma (15 [60%]), neurofibroma (five [20%]), malignant peripheral nerve sheath tumor (four [16%]), and desmoid tumor (one [4%]). CONCLUSIONS: Primary tumors arising in the brachial plexus are rare. Careful workup, surgical technique, and attention to pathological diagnosis optimize management.

Adult↗
PubMed2004

Modification of the mean-square error principle to double the convergence speed of a special case of Hopfield neural network used to segment pathological liver color images.

BACKGROUND: This paper analyzes the effect of the mean-square error principle on the optimization process using a Special Case of Hopfield Neural Network (SCHNN). METHODS: The segmentation of multidimensional medical and colour images can be formulated as an energy function composed of two terms: the sum of squared errors, and a noise term used to avoid the network to be stacked in early local minimum points of the energy landscape. RESULTS: Here, we show that the sum of weighted error, higher than simple squared error, leads the SCHNN classifier to reach faster a local minimum closer to the global minimum with the assurance of acceptable segmentation results. CONCLUSIONS: The proposed segmentation method is used to segment 20 pathological liver colour images, and is shown to be efficient and very effective to be implemented for use in clinics.

Algorithms↗
PubMed2003

Comparison of growth hormone-producing and non-growth hormone-producing pituitary adenomas: imaging characteristics and pathologic correlation.

PURPOSE: To identify characteristic features of growth hormone (GH)-producing pituitary adenomas. MATERIALS AND METHODS: A total of 174 pathologically proven pituitary adenomas were evaluated retrospectively on magnetic resonance (MR) images to determine the signal intensity (on T2-weighted images), maximum diameter, and amount of suprasellar and infrasellar extension. For microadenomas, sellar depth was also measured. GH-producing adenomas were classified at histologic evaluation as densely or sparsely granulated. Specimens from 38 adenomas were stained to assess the amounts of fibrous tissue, iron, and amyloid they contained. Results were correlated with the size and hormonal activity of adenomas by using the chi2, unpaired t, and Mann-Whitney U tests. RESULTS: Among 174 pituitary adenomas, 42 were GH-producing adenomas. Of these, 16 were densely granulated, and 24 were sparsely granulated (two histologic specimens were lost). Signal intensity was evaluated among 153 adenomas. On T2-weighted MR images, hypointensity was seen more commonly in adenomas that produced GH (16 of 40 cases [40%]; P <.001) than in those that did not; hypointensity was nearly exclusive to densely granulated GH-producing adenomas. The amounts of amyloid, fibrous tissue, and iron contained in adenomas demonstrated little relationship with signal intensity. Average suprasellar extension was significantly smaller in adenomas that produced GH (-0.8 mm) than in those that did not (5.3 mm) (P <.001). GH-producing adenomas tended to demonstrate infrasellar extension rather than suprasellar extension. Average sellar depth associated with GH-producing microadenomas (13.3 mm) was significantly greater than for non-GH-producing microadenomas (9.7 mm; P <.001). CONCLUSION: Characteristic features regarding growth direction and T2 signal intensity can be identified for GH-producing adenomas.

Adenoma↗
PubMed2004

Adrenal masses: mr imaging features with pathologic correlation.

The detection of adrenal lesions has increased with the expanding use of cross-sectional imaging. Magnetic resonance (MR) imaging is often useful for characterizing adrenal masses. Adrenal masses can be classified into various groups on the basis of the presence of intracellular lipid, macroscopic fat, hemorrhage, and cystic changes and the vascularity and shape of the tumor. These imaging features can be used by the radiologist to suggest or confirm a diagnosis for most adrenal masses, including adenoma, hyperplasia, simple and complicated cysts, lymphangioma, myelolipoma, pheochromocytoma, hemorrhage, cortical carcinoma, neuroblastoma, lymphoma, and metastases. Adenomas and metastases are common, and a decrease in signal intensity on out-of-phase images can be used to differentiate between them. Carcinoma is a possible diagnosis if that decrease in signal intensity is heterogeneous. Benign disease is diagnosed if macroscopic fat or a homogeneous cystlike lesion is seen. Recognition of the typical MR imaging features is important because it often changes the treatment approach and may obviate surgery.

Adrenal Gland Diseases↗
PubMed1981

Image processing in pathology. X. Electron microscopic morphometric analysis of human lymphocyte subpopulations.

In the present paper, methods of automatic image processing were used for a fine structural differentiation of lymphocyte subpopulations in purified non-labelled lymphocyte suspensions from peripheral blood. It was found that lymphocyte subpopulations differ in several morphological features which have been generated from the whole cell as well as from the nucleus. In general, these differences are greater than those attributed to individual deviations as well as as to influences from the preparation. As found by immunological methods, the composition of morphologically determined subpopulations corresponds to T- and non- T-cells. A preliminary functional interpretation fo the morphological differences is discussed.

Adult↗
PubMed1999

Nonlinear elastic registration of brain images with tumor pathology using a biomechanical model.

A biomechanical model of the brain is presented, using a finite-element formulation. Emphasis is given to the modeling of the soft-tissue deformations induced by the growth of tumors and its application to the registration of anatomical atlases, with images from patients presenting such pathologies. First, an estimate of the anatomy prior to the tumor growth is obtained through a simulated biomechanical contraction of the tumor region. Then a normal-to-normal atlas registration to this estimated pre-tumor anatomy is applied. Finally, the deformation from the tumor-growth model is applied to the resultant registered atlas, producing an atlas that has been deformed to fully register to the patient images. The process of tumor growth is simulated in a nonlinear optimization framework, which is driven by anatomical features such as boundaries of brain structures. The deformation of the surrounding tissue is estimated using a nonlinear elastic model of soft tissue under the boundary conditions imposed by the skull, ventricles, and the falx and tentorium. A preliminary two-dimensional (2-D) implementation is presented in this paper, and tested on both simulated and patient data. One of the long-term goals of this work is to use anatomical brain atlases to estimate the locations of important brain structures in the brain and to use these estimates in presurgical and radiosurgical planning systems.

Biomechanical Phenomena↗
PubMed1998

Evaluation of modern pathologic nomenclature, tumor imaging and treatment of pituitary adenomas in a recent surgical series.

This study reviews retrospectively 49 patients with pituitary adenomas, using a modern, immunohistochemically and ultrastructurally-based nomenclature. It also compares tumor imaging by CT and MRI scans, and analyzes the results of recent neurosurgical and radiotherapeutic treatments. Based on the findings of the study, several recommendations on clinical management of pituitary macroadenoma are made.

Adenoma↗
PubMed2002

T1-weighted hyperintensity in basal ganglia at brain magnetic resonance imaging: are different pathologies sharing a common mechanism?

Basal ganglia bilateral symmetric hyperintensity in T1-weighted sequences at magnetic resonance imaging (MRI) is recognized to be due to the presence of manganese deposits. This abnormal finding has been reported in occupational exposures, liver cirrhosis and total parenteral nutrition with unbalanced solutions. However, the same imaging is often observed "by chance" in brain MRIs of patients not belonging to these groups. In order to better understand which are the clinical conditions coexisting with such findings, we decided to study systematically patients which showed this kind of imaging, focusing on their manganese and iron status, as it is known that these two metals have similar properties and that iron-deficiency can competitively increase manganese absorption. The 20 patients studied underwent clinical evaluation and the following laboratory tests: whole blood iron and manganese, hemoglobin, plasma iron, transferrin and ferritin. The neuroradiologic evaluation was integrated by pallidal index calculation, in order to provide a semi-quantitative esteem of the hyperintensity. The patients could be classified into four subgroups: Parkinsonism, anemia, cirrhosis, central nervous system tumors. In 18 out of 20 cases, we found abnormalities in iron and/or manganese-related values. Particularly, iron-deficiency seems to be frequent among patients showing brain MRI abnormalities compatible with manganese deposits in basal ganglia. This observation suggests that iron-deficiency could be an important risk factor for manganese-induced neurotoxicity and should, therefore, be accurately considered and treated.

Adult↗
PubMed1993

Reactive soft-tissue mass associated with osteoid osteoma: correlation of MR imaging features with pathologic findings.

The authors retrospectively reviewed three cases of histologically documented osteoid osteoma in which magnetic resonance (MR) imaging was performed prior to surgical excision. In all three cases, MR imaging demonstrated abnormal signal intensity characteristics, and use of gadopentetate dimeglumine resulted in enhancement. These findings correlated with a reactive soft-tissue mass with myxomatous change, as well as with cell-depleted, juxtanidal bone marrow that contained proteinaceous material. These MR imaging findings can easily be confused with those of a malignant tumor or osteomyelitis.

Adolescent↗
PubMed2000

The thyroid and parathyroid glands. CT and MR imaging and correlation with pathology and clinical findings.

Thyroid imaging approach is based on the preliminary clinical evaluation. Lesions that are smaller than 2 cm should be assessed with US, which is capable of discriminating masses as small as 2 mm and distinguishing solid from cystic nodules. US-guided FNAB provides tissue for cytologic examination of thyroid nodules. CT and MR imaging are indicated for larger tumors (greater than 3 cm diameter) that extend outside the gland to adjoining structures, including the mediastinum, and retropharyngeal region. Metastatic lymph nodes in the neck and invasion of the aerodigestive tract are also in the realm of CT and MR imaging. Thyroid nodules are categorized on scintigraphy as hot or cold nodules. Hot nodules are rarely malignant, whereas cold nodules have an incidence of 10% to 20% of malignancy. Calcifications (amorphous, globular, nodular, and linear) occur in adenomas and carcinomas and have no differential diagnostic features except for psammomatous calcifications, which are a pathognomonic finding in papillary carcinomas and a small percentage of medullary carcinomas. Papillary carcinoma is the most common malignant tumor (80%) followed by follicular (20% to 25%); medullary (5%); undifferentiated; anaplastic carcinomas (< 5%); lymphoma (5%); and metastases. Lymph node metastases are common in papillary carcinoma, 50% at presentation, and less common in follicular carcinomas. The metastatic nodes in papillary carcinoma may enhance markedly (hypervascular); show increased signal intensity on T1-weighted images (increased thyroglobulin content or hemorrhage); and reveal punctate calcifications. Localized invasion of the larynx, trachea, and esophagus occurs predominantly in papillary and follicular carcinomas; the incidence is less than 5%. Ectopic thyroid tissue may be encountered in the tongue (foramen cecum); along the midline between posterior tongue and isthmus of thyroid gland; lateral neck; mediastinum; and oral cavity. Goiter and malignant tumors, notably papillary carcinoma, may develop in ectopic thyroid tissue. Carcinomas may also arise in thyroglossal duct cysts, which develop from duct remnants between the foramen cecum and thyroid isthmus. Infectious disease of the thyroid gland is not common and the CT and MR imaging findings are similar as described under neck infection. Other types of inflammatory disorders including Hashimoto's thyroiditis, granulomatous thyroiditis, and Riedel's struma display no specific imaging features. Imaging studies may, however, be indicated to confirm a suspected clinical diagnosis and assess compromise of the airway (Riedel's struma). HPT is a clinical diagnosis in which hypercalcemia is the most important finding. Parathyroid hyperplasia, adenoma, and carcinoma represent underlying lesions. To relieve the patient's symptoms surgical extirpation is indicated. The surgical success rate without imaging is 95%. The indications for imaging studies vary but it is generally agreed that reoperation after a previous failed surgical attempt and suspicion of an ectopic parathyroid adenoma should be investigated by imaging. These consist of US, nuclear medicine studies, CT and MR imaging. US and technetium sestamibi scanning have the highest accuracy rate for localizing an adenomatous gland at and near the thyroid gland. Ectopic adenomas, particularly if they are located in the mediastinum, are preferrably investigated with CT and MR imaging with gadolinium and fat suppression. Carcinomas and parathyroid cysts are optimally evaluated by CT and MR imaging. On MR imaging adenomas are low in signal intensity on T1-weighted images, high in signal intensity on T2-weighted images, and enhance post introduction of gadolinium.

Carcinoma↗