Experimental headache models in animals and humans

Using multiple regression analysis, six MR parameters were correlated with three histological grades among 43 proven adult supratentorial astrocytic gliomas to ascertain important MR parameters and their optimal contributions. Analysis revealed that two parameters, border definition and tumor hemorrhage, were unreliable. Using the remaining four parameters an equation was derived: Tumor grade = 0.32 (ring enhancement) +0.29 (degree of contrast enhancement) +0.13 (heterogeneity) +0.12 (edema) +0.41. Ring enhancement was the most reliable predictor of tumor grade, followed by degree of contrast enhancement. The maximum accuracies of the "semi-automatic" approach using this equation for predicting low-grade astrocytomas, anaplastic astrocytomas, and glioblastoma multiforme were 91%, 83%, and 88%, respectively. Although "semi-automatic" grading provided relatively high accuracy, possible sampling errors and some atypical cases reduced such accuracy.     

Intraoperative electron beam radiotherapy for previously irradiated advanced head and neck malignancies

In patients with malignant astrocytomas or metastatic brain disease treated with high-dose radiotherapy, conventional imaging methods may not adequately distinguish recurrent tumor from radiation change. We used a fast spoiled gradient refocusing technique in the open-configuration intraoperative MR system to assess the rate of regional enhancement of the treated tumor bed and to localize specific sites for pathologic sampling to determine whether gadolinium uptake correlated with histologic data. Twenty-four patients were studied. Fourteen of 15 patients with areas of early enhancement had recurrent tumor present in histologic samples, and 8 of the remaining 9 patients had only reactive changes. Dynamic MRI was predictive of recurrent tumor (P < .0005, Fisher exact test and P < .002, Student t test). We conclude that dynamic MRI in the open-bore magnet is a promising method for localizing potential sites of active tumor growth in patients treated for malignant astrocytomas and metastatic brain lesions.     

Pleomorphic xanthoastrocytoma: DNA flow cytometry and outcome analysis of 12 patients

BACKGROUND: Pleomorphic xanthoastrocytoma (PXA) is an astrocytic tumor occurring primarily in childhood and adolescence with some malignant histologic features but a relatively slow clinical course. However, some tumors progress more rapidly and can undergo malignant degeneration. The authors attempted to determine whether various histologic features or tumor cell proliferative indices might help identify lesions at risk for early progression and distinguish PXAs from malignant gliomas. METHODS: In a retrospective study of 12 patients with PXA, the tumor's histologic features and DNA flow cytometric parameters were compared with their clinical course. DNA flow cytometry values for the S- and G2-phase of the PXAs also were compared with control group samples of malignant and low grade astrocytomas. RESULTS: Of the 12 tumors at initial diagnosis, 5 were considered typical PXAs whereas 7 had some atypical features (4 with paucity of reticulin fibers, 1 with focal necrosis, and 2 with both atypical reticulin and focal necrosis). During the follow-up period (range, 3.75-11 years; mean, 6.8 years), 2 patients had recurrences; 1 atypical reticulin PXA progressed to glioblastoma after 6.5 years and the 1 tumor with focal necrosis recurred at 6 months and again at 2 years with typical histologic features. DNA flow cytometry parameters of the typical PXA group were similar to values for malignant astrocytoma and significantly higher than values for control specimens of low grade astrocytomas. There were no distinctive DNA flow cytometric features that could distinguish this last tumor from others with a more benign clinical course. CONCLUSIONS: Measurements of the S-phase and G2-phase obtained from DNA flow cytometry and atypical histologic features cannot reliably identify PXA patients at risk for early progression and overall are significantly higher than values obtained for low grade gliomas. Therefore, frequent (i.e., two to three times per year) postoperative clinical and radiologic examinations are necessary to judge the appropriateness of adjuvant therapy in patients with PXA. The paradox of slow growth but DNA flow cytometry consistent with aggressive malignant lesions may represent a cell-cycle arrest mechanism in these lesions that could be verified in subsequent studies.     

Focal calvarial bone lesions. Comparison of logistic regression and neural network models

RATIONALE AND OBJECTIVES: To assess the accuracy of logistic regression (LR) and artificial neural networks (NN) in the diagnosis of calvarial lesions using computed tomography (CT) and to establish the importance of the different features needed for the diagnosis. METHODS: One hundred sixty-seven patients with calvarial lesions as the only known disease were enrolled. The clinical and CT data were used for LR and NN models. Both models were tested with the leave-one-out method. The final results of each model were compared using the area under receiver operating characteristic curves (Az). RESULTS: Of the lesions, 73.1%, were benign and 26.9% were malignant. There was no statistically significant difference between LR and NN in differentiating malignancy. In characterizing the histologic diagnoses, NN was statistically superior to LR. Important NN features needed for malignancy classification were age and edge definition, and for the histologic diagnoses matrix, marginal sclerosis, and age. CONCLUSION: NNs offer wide possibilities over statistics for the study of calvarial lesions other than their superior diagnostic performance.     

Magnetic resonance imaging changes after stereotactic radiation therapy for childhood low grade astrocytoma

BACKGROUND: Stereotactic radiotherapy (SRT) is fractionated radiotherapy delivered under stereotactic guidance to produce highly focal and precise therapy. We studied the incidence of imaging changes that can mimic tumor progression after completion of SRT for childhood low grade astrocytoma. METHODS: Between June 1992 and September 1994, we prospectively treated 28 children with low grade astrocytomas with SRT. The patients ranged in age from 2 to 22 years (median: 10 yrs) and none had received prior radiation therapy or radiosurgery. Routine fractionation was employed (180-200 centigray[cGy]) to a total dose of 5220-6000 cGy over 5 to 6 weeks. All of the patients underwent initial and follow-up magnetic resonance imaging (MRI) according to protocol. RESULTS: Median clinical follow-up for the 28 patients was 24 months (range, 5-32 mos) with a median radiographic follow-up of 15 months (range, 3-26 mos). Fifteen patients had reduction in tumor size, one patient had stable disease. Twelve patients (43%) developed increased size of the lesion, increased signal intensity or enhancement, cysts or cavitations, and an increase in edema or mass effect on follow-up MRI. Most of these changes occurred between 9 and 12 months after the start of SRT and resolved or decreased by 15 to 21 months. All but one patient had normal or stable neurologic examinations. CONCLUSIONS: Treatment-related MRI changes are common after conventionally fractionated schedules using stereotactic radiation techniques for patients with low grade astrocytomas. These changes can be distinguished from tumor progression by their transient nature as well as the general absence of clinical symptoms.     

Immunohistochemical analysis of metallothionein in astrocytic tumors in relation to tumor grade, proliferative potential, and survival

BACKGROUND: Metallothionein (MT) is the name for a family of predominantly intracellular protein thiol compounds involved in anticancer drug resistance. For certain tumors, MT is related to grade of tumor malignancy and prognosis. The authors evaluated the expression of MT in 114 astrocytic tumors in relation to the proliferative potential of tumors and the survival of patients. METHODS: Paraffin embedded tissue sections were stained with monoclonal anti-metallothionein and MIB-1 Ki-67 antibodies by avidin-biotin complex immunohistochemistry. RESULTS: MT expression was observed in 2 of 6 pilocytic astrocytomas, in 10 of 24 Grade 2 astrocytomas, in 16 of 25 anaplastic astrocytomas, and in 47 of 59 glioblastomas. In addition to the tumor cells, microvascular endothelial proliferation and smooth muscle of tumor vessel walls were frequently MT positive. The glioblastomas had a significantly higher percentage of MT positive cells compared with low grade (P < 0.0001) and anaplastic (P < 0.04) astrocytomas. MT expression in astrocytomas had no correlation with tumor recurrence. The mean Ki-67 labeling index (LI) was significantly higher in the high grade (3-4) compared with the low grade (1-2) astrocytomas. MT positive astrocytic tumors had statistically significantly higher mean Ki-67 LI compared with MT negative tumors, irrespective of histologic grade. Although the levels of MT and Ki-67 LI varied in individual tumors, the mean Ki-67 LI increased in parallel to the increasing MT staining grade, and this difference attained statistical significance only for glioblastoma. MT positive anaplastic astrocytoma and glioblastoma patients did not survive as long as the MT negative patients, although this difference attained statistical significance only for anaplastic astrocytoma. CONCLUSIONS: The current study suggests that MT might play a significant role in the growth of astrocytic tumors, with an acquired enhanced ability to produce MT as the malignant potential of a tumor increases.     

Chondromalacia of the knee: evaluation with a fat-suppression three-dimensional SPGR imaging after intravenous contrast injection

Twenty-one MRI studies with a fat-suppression three-dimensional spoiled gradient-recalled echo in a steady state (3D SPGR) pulse sequence after intravenous contrast injection were evaluated to assess the accuracy in depicting chondromalacia of the knee. On the basis of MR images, chondromalacia and its grade were determined in each of five articular cartilage regions (total, 105 regions) and then the results were compared to arthroscopic findings. The sensitivity, specificity, and accuracy of MRI were 70%, 99%, and 93%, respectively. MR images depicted 7 of 11 lesions of arthroscopic grade 1 or 2 chondromalacia, and seven of nine lesions of arthroscopic grade 3 or 4 chondromalacia. The cartilage abnormalities in all cases appeared as focal lesions with high signal intensity. Intravenous contrast-injection, fat-suppression 3D SPGR imaging showed high specificity in excluding cartilage abnormalities and may be considered as an alternative to intra-articular MR arthrography when chondromalacia is suspected.     

Immunohistochemical analysis of progesterone receptor and Ki-67 labeling index in astrocytic tumors

BACKGROUND: Intracranial tumors such as meningiomas express steroid hormone receptors but little is known regarding progesterone receptor (PR) in astrocytic tumors. The authors evaluated expression of PR in 86 astrocytic tumors in relation to tumor proliferative potential. METHODS: Paraffin embedded tumor sections were stained with polyclonal antiprogesterone antibody by the peroxidase-antiperoxidase method and with monoclonal MIB-1-Ki-67 antibody by avidin-biotin complex immunohistochemistry. RESULTS: Sixty-three of the 86 astrocytic tumors (73%) showed positive PR immunoreactivity. PR expression was observed in 4 of 9 pilocytic astrocytomas, 13 of 24 Grade 2 astrocytomas, 15 of 20 anaplastic astrocytomas, and 31 of 33 glioblastomas. In addition to the tumor cells, cells of microvascular endothelial proliferation and the smooth muscle of tumor vessel walls were frequently PR positive. Glioblastomas had a significantly higher percentage of PR positive cells compared with anaplastic (P < 0.0008) and low grade (P < 0.0001) astrocytomas. Patients with PR positive astrocytomas were of an older age than patients with PR negative astrocytomas (48.71 +/- 21.95 years vs. 37.09 +/- 24.69 years; P < 0.04). The mean Ki-67 labeling index (LI) was significantly higher in the high grade (3-4) astrocytomas compared with low grade (1-2) astrocytomas (P < 0.0001). PR positive astrocytic tumors had higher Ki-67 LI than PR negative tumors. PR expression was not correlated with tumor recurrence and patient survival. CONCLUSIONS: The current study suggests that PR in the astrocytic tumors correlates with histologic grade and PR may participate in the growth of these tumors and tumor angiogenesis. The measurement of PR in these tumors may indirectly represent tumor growth potential.     

Evaluation of complications of kidney transplantation using artificial neural networks

The aim of this study was to develop an artificial neural network (ANN) to differentiate between rejection, acute tubular necrosis (ATN) and normally functioning kidneys in a group of patients with renal transplants. The performance of ANN was compared with that of an experienced observer using a database of 35 patients' records, each of which included 12 quantitative parameters derived from renograms and clinical data as well as a clinical evaluation. These findings were encoded as features for a three-layered neural network to predict the outcome of biopsy or clinical diagnosis. The network was trained and tested using the jackknife method and its performance was then compared to that of a radiologist. The network was able to correctly classify 31 of the 35 original cases and gave a better diagnostic accuracy (88%) than the radiologist (83%), by showing an association between the quantitative data and the corresponding pathological results (r = 0.78, P < 0.001). We conclude that an ANN can be trained to differentiate rejection from acute tubular necrosis, as well as normally functioning transplants, with a reasonable degree of accuracy.     

Epidermal growth factor receptor: an independent predictor of survival in astrocytic tumors given definitive irradiation

PURPOSE: To determine whether the expression of epidermal growth factor receptor (EGFR) protein was predictive of patient survival independently of other prognostic factors in astrocytic tumors. METHODS AND MATERIALS: Epidermal growth factor receptor protein expression was investigated immunohistochemically in formalin-fixed, paraffin-embedded surgical specimens of 55 glioblastoma multiforme, 14 anaplastic astrocytoma, and 2 astrocytomas given definitive irradiation. We evaluated the relationship of EGFR protein expression and tumor grade, histologic features, age at diagnosis, sex, patient survival, and recurrence-free survival. RESULTS: The percentage of tumor cells which were EGFR positive related to reduced survival by Cox regression analysis in both univariate (p = 0.0424) and multivariate analysis (p = 0.0016). Epidermal growth factor receptor positivity was the only 1 of 11 clinical and histological variables associated with decreased recurrence-free survival by either univariate (p = 0.0353) or multivariate (p=0.0182) analysis. Epidermal growth factor receptor protein expression was not related to patient age, sex, or histologic features. CONCLUSION: Epidermal growth factor receptor positivity was a significant and independent prognostic indicator for overall survival and recurrence-free survival for irradiated patients with astrocytic gliomas.     

Nonlinear Models for Predicting Hoisting Times of Tower Cranes

Accuracy in estimating activity duration is one of the key prerequisites for successful construction planning. Efficient material transportation plays an important role in reducing costs and time. Time measurement and work-study techniques can provide good estimation of activity duration, but forming the databank for various conditions is expensive. The use of empirical models has been developed as an alternative to overcome the deficiency while maintaining a reasonable accuracy. In this research traditional linear regression models and nonlinear neural network models have been developed for predicting hoisting times of a tower crane. It is found that nonlinear neural network models can achieve higher accuracy. However, planners may find that the regression models, which describe the relationship between the variables in more simplistic terms, could allow them to shorten the hoisting times by manipulating the input variables. The results and the merits of the models are discussed.     

金矿浮选回收率预测模型

浮选回收率是金矿选矿过程重要的生产指标,目前主要是通过人工化验的方法检测获得,人工检测周期较长,造成金矿厂不能及时把握浮选工艺水平.在大量现场生产数据的基础上,分别采用多元线性回归和BP神经网络的方法,建立了金矿厂浮选回收率的预测模型.预测误差分析表明,BP神经网络预测模型能较好地预测金矿厂的浮选回收率,当预测相对误差在±3%范围内时,模型的预测精度达到91%,对于实际生产具有良好的参考作用.      

Quantitative imaging study of extent of surgical resection and prognosis of malignant astrocytomas

OBJECTIVE: This study used quantitative radiological imaging to determine the effect of surgical resection on postoperative survival of patients with malignant astrocytomas. Previous studies relied on the surgeons' impressions of the amount of tumor removed, which is a less reliable measure of the extent of resection. METHODS: Information concerning possible prognostic factors was collected for 75 patients undergoing magnetic resonance imaging or computed tomography preoperatively and within 10 days postoperatively. Image analysis of the neuroradiological studies was conducted to quantify pre- and postoperative total tumor volumes and enhancing volumes. Univariate and multivariate proportional hazards models were used to analyze the regression of survival regarding 22 covariates that might affect survival. The covariates that were entered included age, gender, tumor grade, cumulative radiation dose, chemotherapy, seizures as a first symptom, Karnofsky performance status at presentation, pre- and postoperative total and enhancing tumor volumes, ratio of pre- to postoperative total and enhancing tumor volumes, tumor location, surgeon's impression of the degree of resection, and subsequent surgery. RESULTS: There were 23 patients with anaplastic astrocytomas and 52 with glioblastomas multiforme. The estimated mean survival time was 27 months for patients undergoing gross total resection, 33 months for subtotal resection, and 13 months for open or stereotactic biopsy. Five factors that were significant predictors of survival in multivariate analysis were tumor grade, age, Karnofsky performance status, radiation dose, and postoperative complications (P < 0.05). In univariate analysis, tumor grade, radiation dose, age, Karnofsky status, complications, presence of enhancing tumor in postoperative imaging, and postoperative volume of enhancing tumor were significantly associated with survival (P < 0.05). CONCLUSION: We conclude that the most important prognostic factors affecting survival of patients with anaplastic astrocytomas and glioblastomas multiforme are tumor grade, age, preoperative performance status, and radiation therapy. Postoperative complications adversely affect survival. Aggressive surgical resection did not impart a significant increase in survival time. Surgical resection may improve survival, but its importance is less than that of other factors and may be demonstrable only by larger studies.     

Immature teratoma of the ovary with a neural component ("solid" teratoma). A clinicopathologic study of 20 cases

Twenty cases of immature teratoma of the ovary with a neural component are analyzed. A plea is made for use of the nomenclature adopted from the new World Health Organization classification of ovarian tumors, the past confusion over terminology and histogenesis of this rare tumor is discussed. All the primary tumors in the present series contained at least some immature tissues (predominantly of neural origin) and were thus graded from 1 to 3 according to the criteria of Thurlbeck and Scully. No grade 0 tumors ("benign solid teratomas") were identified. We believe that thorough sectioning almost always insures the identification of immature elements. The prognosis was closely related to the histologic grade, but correlated poorly withthe clinical stage, the latter being influenced by the common finding (25 per cent of the cases in this series) of peritoneal implants composed exclusively of mature glial tissue, which is associated with a benign clinical evolution. This phenomenon of maturation or differentiation appears to be the rule rather than the exception in this tumor, since implants are usually of better or equal differentiation when compared with their primary tumors and older patients tend to have lower grade tumors than younger patients. Since the majority of patients with this tumor are young, primary surgical therapy should be conservative, unilateral salpingooophorectomy often being sufficient. Spontaneous or operative rupture of the tumor capsule carries an increased risk of subsequent dissemination. We have noted impressive clinical responses in patients with disseminated tumors of a high histologic grade after treatment with triple chemotherapy (vincristine, actinomycin D, and cyclophosphamide) but do not recommend adjuvant therapy in patients with only grade 0 implants.     

MIB-1 proliferation index predicts survival among patients with grade II astrocytoma

The purpose of this study was to determine whether a relationship existed between MIB-1 labeling index (LI) percentages and survival in patients with grade II astrocytomas. From archival paraffin-embedded surgical specimens of 50 patients of the University of Michigan Medical Center with World Health Organization grade II astrocytomas, 22 patients had a Ki-67 LI of less than or equal to 2.0; and 28 patients had a MIB-1 LI of more than 2.0. Over a median follow-up interval of 10 years, ranging up to 16 years, 23% (n = 5) died of tumor in the first group while 82% (n = 23) died in the second group, a distinct difference in survival between these groups. Univariate analysis showed that a high MIB-1 predicted shorter survival (p < 0.0001), and that increased age was associated with shorter survival (p = 0.007). Gender, tumor location and radiotherapy had no significant association with survival. When adjusting for these (excluding tumor location) in the Cox proportional hazards model simultaneously, MIB-1 and age were independently prognostic. The hazard ratios were 1.301 per 1% MIB-1 LI (p = 0.0001), and 1.045 per year of age (p = 0.0028). From other studies, we know that histopathologic grade and age predict survival for glioma patients. However, even within grade II astrocytomas there is still a wide heterogeneity in how long a patient survives. We conclude that among grade II astrocytomas older patients and, independently, patients with higher MIB-1 labeling index have shorter survival.     

Expression of oligodendrocytic mRNAs in glial tumors: changes associated with tumor grade and extent of neoplastic infiltration

We examined the expression of glial- and neuronal-specific mRNAs within human gliomas using in situ hybridization. We found that low-grade astrocytomas contained a high number of proteolipid protein (PLP) mRNA-positive cells and that the number of PLP-stained cells decreased markedly with increasing tumor grade. Interestingly, the ratio of PLP mRNA-stained cells:myelin basic protein (MBP) mRNA-stained cells in normal white matter and low-grade astrocytoma was about 2:1 but approached 1:1 with increasing tumor grade. This parameter appeared to be a good indicator of tumor infiltration in astrocytomas, so we tested this in the analysis of other gliomas. Unlike astrocytomas, oligodendrogliomas were found consistently to contain few PLP mRNA- or MBP mRNA-expressing cells. In contrast, gemistocytic astrocytomas, typically highly invasive tumors, contained high numbers of PLP-positive cells and a ratio of PLP mRNA:MBP mRNA-stained cells of about 1.5:1, similar to low-grade astrocytomas. Nonradioactive in situ hybridization also enabled the morphological identification of specific cells. For example, gemistocytic astrocytes, which were found to be strongly vimentin mRNA positive, contained little glial fibrillary acidic protein mRNA and did not stain for PLP or MBP mRNAs. Neuronal mRNAs, such as neurofilament 68, were observed in small numbers of entrapped neurons within gliomas but were uninformative with respect to predicting tumor grade. Our results suggest that oligodendrocytes survive low-grade tumor infiltration and that glial tumor cells, unlike cell lines derived from them, do not express oligodendrocyte or neuronal mRNAs. In addition, the expression of mRNAs for the two major myelin protein genes, PLP and MBP, could be used to predict the grade and extent of tumor infiltration in astrocytomas.     

Comparison of hot rolled steel mechanical property prediction models using linear multiple regression,non-linear multiple regression and non-linear artificial neural networks

Abstract

In the manufacture of rolled steel from a hot strip mill, the final mechanical properties, such as yield strength, ultimate tensile strength and elongation to fracture, are important requirements specified by the customer. The use of mathematical modelling techniques such as multiple regression analysis, or computational developments such as artificial neural networks, can result in the creation of acceptably accurate predictive models. However, the accuracy of any predictive model will depend on the quality of data used in its creation, and thus a brief statistical analysis of the mechanical property data used for model development is discussed. In the present paper a comparison of the application of linear multiple regression, non-linear multiple regression and non-linear neural networks is made for various steel families using data taken from the Corus Port Talbot hot strip mill. A statistical summary of their relative predictive errors is given, and although all three are comparable, the non-linear, black box approach of a suitably structured neural network provides overall more accurate predictive models than the use of linear or non-linear multiple regression.     

Accumulation of genetic changes is associated with poor prognosis in grade II astrocytomas

Unexpectedly aggressive clinical course of some grade II astrocytomas is a diagnostic dilemma for routine histopathology. Because increasing tumor malignancy is a consequence of progressive accumulation of chromosomal alterations, we investigated whether aggressive behavior of grade II astrocytomas could be predicted by the number and type of gross chromosomal aberrations. We used comparative genomic hybridization to analyze 11 grade II astrocytomas with typical (good, n = 7) or poor (n = 4) prognosis. The results were also compared with a reference material of 13 grade III-IV astrocytomas and nine established cell lines. We found a median of two aberrations (range 0 to 4) in tumors with good prognosis and of 15.5 changes (range 8 to 28) in tumors with poor prognosis. Chromosomal gains were present in both groups, whereas chromosomal losses were frequent in tumors with poor prognosis (median 9.5, range 3 to 14) but rare in tumors with good prognosis (range 0 to 2). All chromosomal gains were also found in the high-grade astrocytoma group and the majority of them in cell lines. Chromosomal losses in grade II astrocytomas with poor prognosis were very similar to those in grade III-IV astrocytomas and cell lines. We conclude that an early accumulation of genetic changes in grade II astrocytomas is closely associated with poor patient prognosis, suggesting diagnostic use for comparative genomic hybridization in characterization of grade II astrocytomas.     

The clinical utility of magnetic resonance imaging in 3-dimensional treatment planning of brain neoplasms

Results of the clinical experience gained since 1986 in the treatment planning of patients with brain neoplasms through integration of magnetic resonance imaging (MRI) into computerized tomography (CT)-based, three-dimensional treatment planning are presented. Data from MRI can now be fully registered with CT data using appropriate three-dimensional coordinate transformations allowing: (a) display of MRI defined structures on CT images; (b) treatment planning of composite CT-MRI volumes; (c) dose display on either CT or MRI images. Treatment planning with non-coplanar beam arrangements is also facilitated by MRI because of direct acquisition of information in multiple, orthogonal planes. The advantages of this integration of information are especially evident in certain situations, for example, low grade astrocytomas with indistinct CT margins, tumors with margins obscured by bone artifact on CT scan. Target definitions have repeatedly been altered based on MRI detected abnormalities not visualized on CT scans. Regions of gadolinium enhancement on MRI T1-weighted scans can be compared to the contrast-enhancing CT tumor volumes, while abnormalities detected on MRI T2-weighted scans are the counterpart of CT-defined edema. Generally, MRI markedly increased the apparent macroscopic tumor volume from that seen on contrast-CT alone. However, CT tumor information was also necessary as it defined abnormalities not always perceptible with MRI (on average, 19% of composite CT-MRI volume seen on CT only). In all, the integration of MRI data with CT information has been found to be practical, and often necessary, for the three-dimensional treatment of brain neoplasms.     

Few microorganisms associated with bacterial vaginosis may constitute the pathologic core: a population-based microbiologic study among 3596 pregnant women

OBJECTIVE: To evaluate if pelvic magnetic resonance imaging (MRI) is reliable for differentiating leiomyoma subtypes. DESIGN: Prospective study. SETTING: Academic center. PATIENT(S): Forty-five patients underwent MRI before surgery for leiomyomata. INTERVENTION(S): One radiologist blinded to patient history and histologic diagnosis recorded the MRI characteristics and classification of the largest leiomyoma. MAIN OUTCOME MEASURE(S): Comparison of MRI and histologic diagnoses. RESULT(S): Leiomyoma subtypes were diagnosed accurately by MRI in 69% of cases. Magnetic resonance imaging had a 95% sensitivity and 72% specificity for diagnosing an uncomplicated leiomyoma and a 10% sensitivity and 100% specificity for a cellular leiomyoma. For cystic leiomyomata, the sensitivity was 80% and specificity was 98%, and for hemorrhagic leiomyomata, 100% and 86%, respectively. Magnetic resonance imaging correctly diagnosed all malignant tumors and did not incorrectly diagnose a leiomyoma as a leiomyosarcoma in any case. Ill-defined MRI margins were significantly more likely to be leiomyosarcoma, whereas well-defined margins were characteristic of benign lesions. Hemorrhagic leiomyomata were significantly more likely to be hyperintense on T1-weighted images than other subtypes. CONCLUSION(S): Although MRI is only fairly accurate in differentiating the subtypes of benign uterine smooth muscle tumors, signal intensities and margin characteristics are useful to distinguish accurately benign from malignant tumors.