Existence of contralateral abnormalities revealed by texture analysis in unilateral intractable hippocampal epilepsy

We selected 23 patients with unilateral temporal lobe epilepsy characterized by ipsilateral hippocampal sclerosis and an apparently normal contralateral hippocampus on MR imaging. Images were acquired on a 0.28 T MR scanner using a conventional Carr-Purcell Meiboom Gill sequence in all patients and in 9 healthy subjects. Texture analysis was applied to axial MR images of the first and tenth echoes. Texture analysis detects macroscopic lesions and microscopic abnormalities that can not be observed visually. The presence of texture differences in the between normal (controls) and sclerotic hippocampi was ascertained by statistical discriminant analysis. The apparently normal contralateral hippocampi can be classified into three categories in terms of texture: 4 apparently healthy, 8 similar to sclerosis, and 11 different from either healthy or sclerosis. These findings are related to a certain degree of hippocampal alteration, which further investigation might help better characterize.     

Curvilinear reconstruction of 3D magnetic resonance imaging in patients with partial epilepsy: A pilot study

In an attempt to better delineate the abnormalities associated with focal cortical dysgenesis, we performed curvilinear reformatting of the cortex from 3D magnetic resonance (MR) images. Illustrative patients with partial seizures and conventional orthogonal MRI evaluation show that small regions of cortical thickening suggestive of focal dysplastic lesions may not be recognized. In three such patients the curvilinear reformatting demonstrated two additional focal abnormalities of the cortical gyri and better defined the two focal lesions found on conventional orthogonal MR images. This method promises to a be useful tool in the evaluation of epileptic patients with proven or suspected subtle structural cortical abnormalities, particularly focal neuronal migration disorders where cortical thickening, abnormal gyral pattern, and poor delineation of the gray-white matter transition are the main findings.     

Small hyperintense hepatic lesions on T1-weighted images in patients with cirrhosis: evaluation with serial MRI and imaging features for clinical benignity

PURPOSE: The aim of this study was to evaluate the frequency and magnetic resonance imaging (MRI) features of clinically benign, small (<2 cm) hyperintense hepatic lesions in the cirrhotic liver on T1-weighted MR images seen at serial MRI. MATERIALS AND METHODS: This study included 189 patients with cirrhosis, who underwent hepatic MRI more than twice with an interval of at least 12 months. The initial MR images were reviewed for the presence of small hyperintense lesions on T1-weighted images. The size, location and signal intensity on T2-weighted images as well as enhancement patterns of the corresponding lesions were recorded. RESULTS: On the initial T1-weighted MR images, 43 small hyperintense hepatic lesions were detected in 23 (12%) of 189 patients. Twelve (28%) of 43 lesions showed early enhancement and were pathologically diagnosed as hepatocellular carcinoma (HCC) during the follow-up period. Thirty-one (72%) of 43 lesions showed no early enhancement with various signal intensity on T2-weighted images (hyperintensity=4, isointensity=20, hypointensity=7). Among these 31 lesions, 12 showed no interval change, while 11 disappeared (n=10) or decreased in size (n=1). In the remaining eight lesions, seven were diagnosed as HCC on the basis of pathologic confirmation or the interval growth. CONCLUSION: Small hyperintense hepatic lesions on T1-weighted magnetic resonance (MR) images without early enhancement on the arterial-phase contrast-enhanced dynamic studies in patients with cirrhosis usually showed no interval growth or disappeared during the serial MRI. These lesions with additional findings of iso- or hypointensity on the T2-weighted MR images without "washout effect" on the contrast-enhanced equilibrium-phase images may more frequently be clinically benign or hyperplastic nodules than HCCs.     

Comparison of automated and visual texture analysis in MRI: characterization of normal and diseased skeletal muscle

Automated magnetic resonance imaging (MRI) texture analysis was compared with visual MRI analysis for the diagnosis of skeletal muscle dystrophy in 14 healthy and 17 diseased subjects. MRI texture analysis was performed on 8 muscle regions of interest (ROI) using four statistical methods (histogram, co-occurrence matrix, gradient matrix, runlength matrix) and one structural (mathematical morphology) method. Nine senior radiologists assessed full leg transverse slice images and proposed a diagnosis. The 59 extracted texture parameters for each ROI were statistically analyzed by Correspondence Factorial Analysis. Non-parametric tests were used to compare diagnoses based on automated texture analysis and visual analysis. Texture analysis methods discriminated between healthy volunteers and patients with a sensitivity of 70%, and a specificity of 86%. Comparison with visual analysis of MR images suggests that texture analysis can provide useful information contributing to the diagnosis of skeletal muscle disease.     

癫痫大鼠海马神经元生化分子的同步辐射显微红外光谱成像研究

癫痫是影响所有年龄段的慢性脑功能障碍,主要特征为整个或局部脑区神经元异常同步化高频群集动作电位发放。利用神经毒素海人藻酸（KA）立体定位注射入大鼠海马,诱导大鼠产生癫痫持续状态,建立颞叶癫痫大鼠模型。应用同步辐射显微光谱和同步辐射显微光谱成像分析癫痫持续状态发作后24小时的颞叶癫痫大鼠海马角（CA）1区神经元生物化学分子的胞内浓度和分布是否改变。结果显示反映蛋白质二级结构的酰胺Ⅰ在1 655 cm-1的振动频率和属于脂类功能集团的2 800～3 000 cm-1振动频率,在正常对照大鼠海马CA1神经元胞体内呈高浓度分布,但在癫痫大鼠海马CA1神经元胞体,反映蛋白质二级内呈低浓度分布,并且以细胞核分布浓度最低,但在神经元胞体外围分布浓度相对较高。属于核酸集团的1 055～1 054 cm-1 PO₂反对称拉伸振动在正常和癫痫大鼠海马CA1神经元胞体内分布趋势没有差异,都在胞体内呈高浓度分布,尤其在细胞核分布浓度最高。对属于酰胺Ⅰ的吸收频率进行二级导数分析显示癫痫海马神经元的酰胺Ⅰ相对于正常对照多出1个1 653 cm-1附近的负峰。以上结果提示在发生癫痫持续发作后海马神经元生物化学分子的细胞分布会出现变化。     

磁共振成象诊断出血性胆囊炎——离体及活体研究

在离体研究的基础上,对三个出血性胆囊炎的病人术前做出诊断,出血性胆囊炎可分为混合性及非混合性.在离体实验中,如果血液未与胆汁混合,T₁加权象可发现加于10mL胆汁中的0.2mL的血液表现为高信号区;质子密度加权象可发现加于10mL,胆汁中的0.4mL血液表现为稍高信号区;T₂加权象对此不敏感.如果血液与胆汁完全混合,在所有采用的磁共振成象上均使胆汁信号增高.非混合性出血性胆囊炎的磁共振成象具有特征性:在T₁加权象及质子密度加权象胆囊内有高信号区,T₂加权象此区为等信号、低信号或其中心为低信号周围与胆汁相接的为高信号。混合性出血性胆囊炎在所采用的磁共振成象图象中,相对于肝脏,胆囊内容物表现为均匀高信号,临床资料及胆囊壁、胆囊周围渗出有助于这种出血性胆囊炎的诊断.     

Renal-related perinephric fluid collections: MRI findings

We retrospectively reviewed MR studies on 10 patients with renal-related perinephric fluid collections who underwent MRI in three institutions between January 2001 and August 2004. All patients underwent MRI of the abdomen and T1-weighted, T2-weighted and serial contrast-enhanced images, including delayed-phase contrast-enhanced images 10-12 min after contrast injection, were obtained. Perinephric fluid collections in 5 patients revealed MRI findings of simple fluid content (i.e., hypointense on T1-weighted images and hyperintense on T2-weighted images). In another 5 patients, a complex perinephric fluid content (i.e., mixed hyper/hypointense on T1-weighted images and mixed hypo/hyperintense on T2-weighted images compatible with blood breakdown products and pus) was observed. In 5 patients, contrast extravasation on late-phase images that was compatible with urine leak was demonstrated. Our results suggest that MRI may determine the content of perinephric fluid collections on noncontrast T1-weighted and T2-weighted images and that contrast extravasation on late-phase images is associated with urine extravasation from renal collecting systems.     

MRI texture analysis on texture test objects, normal brain and intracranial tumors

Texture analysis was performed in three different MRI units on T1 and T2-weighted MR images from 10 healthy volunteers and 63 patients with histologically confirmed intracranial tumors. The goal of this study was a multicenter evaluation of the usefulness of this quantitative approach for the characterization of healthy and pathologic human brain tissues (white matter, gray matter, cerebrospinal fluid, tumors and edema). Each selected brain region of interest was characterized with both its mean gray level values and several texture parameters. Multivariate statistical analyses were then applied in order to discriminate each brain tissue type represented by its own set of texture parameters. Texture analysis was previously performed on test objects to evaluate the method dependence on acquisition parameters and consequently the interest of a multicenter evaluation. Even obtained on different sites with their own acquisition routine protocol, MR brain images contain textural features that can reveal discriminant factors for tissue classification and image segmentation. It can also offer additional information in case of undetermined diagnosis or to develop a more accurate tumor grading.     

Hemodynamic response (BOLD/fMRI) in focal epilepsy with reference to benzodiazepine effect

We studied a new procedure of BOLD/fMRI acquisition in epilepsy. They use the benzodiazepine effect to achieve a more reliable baseline for statistical analysis. The method works only in the MR domain without EEG correlation. It compares the EPI images during interictal epileptic discharges and the images “inactivated” by benzodiazepine.

The results in five out of eight patients show that this procedure in comparison with the EEG/fMRI method gives a net improvement of spatial definition of BOLD areas. These preliminary results seem to confirm the hypothesis that the better BOLD/fMRI procedure in epilepsy is to make use of physical features of MR that, unlike EEG, is not influenced by the distance of intercerebral sources and consequently allows a more complete and undistorted display of BOLD areas.     

Hepatic alveolar echinococcosis: MRI findings

The purpose of this study was to describe the magnetic resonance imaging (MRI) appearance of hepatic alveolar echinococcosis (HAE) on T(1)-weighted, T(2)-weighted and postgadolinium images. A total of 13 lesions were demonstrated in 13 patients. All patients underwent MR examination at 1 T imager. MR examinations included precontrast T(1)-weighted breathing averaged spin echo (SE), breath-hold spoiled gradient echo, T(2)-weighted TSE sequences with and without fat suppression, and T(1)-weighted breath-hold spoiled gradient echo (SGE) sequence following i.v. after gadolinium administration. All lesions were confirmed with histopathology. HAE hepatic lesions revealed geographic patterns of variable signal intensities on noncontrast T(1)- and T(2)-weighted images. Slightly hyperintense, iso- and hypointense signal on T(1)-weighted images corresponded to calcified regions, which appeared hypo-isointense signal on T(2)-weighted images. Necrotic areas were hypointense signal on T(1)-weighted and hyperintense signal on T(2)-weighted images. On postgadolinium images, lesions did not reveal enhancement. Dilatation of intrahepatic bile ducts distal to HAE abscesses were observed in five patients and portal vein invasion or compression was observed in four patients, lobar atrophy of the liver was coexistent finding in cases with portal vein compression. The MRI appearance of HAE abscesses included large irregularly marginated masses with heterogenous signal on T(1)- and T(2)-weighted images and lack of enhancement with gadolinium.     

Influence of age and osteoporosis on calcaneus trabecular bone structure: a preliminary in vivo MRI study by quantitative texture analysis

Recent developments in high-resolution MR imaging techniques have opened up new perspectives for structural characterization of trabecular bone by non-invasive methods. In this study, 3-D MR imaging was performed on 17 healthy volunteers and 6 osteoporotic patients. Two different MR sequences were used to evaluate the impact on MR acquisition on texture analysis results. Images were analyzed with four automated methods of texture analysis (grey level histogram, cooccurrence, runlength and gradient matrices) enabling quantitative analysis of grey level intensity and distribution within three different regions of interest (ROI). Texture analysis is not very frequently used since the interpretation of the large number of calculated parameters is difficult. We applied multiparametric data analyses such as principal component analysis (CFA) and hierarchical ascending classification (HAC) to determine the relevant parameters to differentiate between three sets of images (healthy young volunteers, healthy postmenopaused and osteoporotic patients). The results suggest that relevant texture information (depending on the ROI localization in the calcaneus) can be extracted from calcaneus MR images to evaluate osteoporosis and age effects on trabecular bone structure if strictly the same acquisition sequences are used for all patients' examination.     

MR characteristics of neoplasms and vascular malformations associated with epilepsy

We assessed the magnetic resonance (MR) imaging characteristics of two categories of epileptogenic substrates, neoplasms, and vascular malformations, to determine MR sensitivity and typical imaging features. A blinded retrospective analysis was performed on MR scans from 41 patients who had a neoplasm or vascular malformation surgically resected as treatment for medically refractory epilepsy. Abnormalities were assessed for sensitivity of MR detection, prediction of pathologic category, location, calvarial remodelling, signal intensity, and effect on adjacent tissue. Pathologic findings consisted of 33 tumors and 8 vascular malformations. We correctly localized 100% of the 41 lesions and predicted the correct pathologic category for 95% of these lesions. Neoplastic and vascular lesions (NVLs) associated with epilepsy had certain characteristic features. The temporal lobe was the most common site for NVL, involved in 68%. NVL were located in the brain periphery in 85% and remodelled the calvarium in 32%. NVL were associated with mass effect in 61%, volume loss in 1%, and no effect on adjacent tissue in 37%. NVL associated with epilepsy can be detected with high sensitivity using MR imaging. The temporal lobe location, cortical involvement, and calvarial remodelling are findings typical of NVL. MR characteristics can successfully predict the pathologic substrate of these lesions.     

Giant hemangioma of the liver: MR imaging characteristics in 24 patients

We retrospectively reviewed the magnetic resonance imaging (MRI) of giant hemangiomas in 24 patients. MRI studies comprised T1-weighted, T2-weighted and serial gadolinium-enhanced spoiled gradient echo (SGE) images. Morphologic features, signal characteristics and enhancement patterns were assessed. Histopathologic evaluation was obtained in nine patients. On T2-weighted images all lesions (size 5.7-24 cm) were hyperintense relative to the spleen and two dominant patterns of heterogeneity were demonstrated: a central heterogeneous area of either bright, dark, or mixed signal intensity, and a network of multiple fibrous septa of low signal intensity. Histopathologic evaluation of two lesions with a central bright area demonstrated the presence of hypocellular myxoid tissue. Central enhancement (9 lesions) and an irregular flame-shaped peripheral pattern of enhancement (12 lesions) were present in lesions with a mean diameter greater than 10 cm. Although giant hemangiomas show greater variability in their MR imaging appearance, an accurate diagnosis can be made through still characteristic features of high signal intensity on T2-weighted images and discontinuous peripheral enhancement.     

An empirical investigation of motion effects in eMRI of interictal epileptiform spikes

We recently developed a functional neuroimaging technique called encephalographic magnetic resonance imaging (eMRI). Our method acquires rapid single-shot gradient-echo echo-planar MRI (repetition time=47 ms); it attempts to measure an MR signal more directly linked to neuronal electromagnetic activity than existing methods. To increase the likelihood of detecting such an MR signal, we recorded concurrent MRI and scalp electroencephalography (EEG) during fast (20-200 ms), localized, high-amplitude (>50 μV on EEG) cortical discharges in a cohort of focal epilepsy patients. Seen on EEG as interictal spikes, these discharges occur in between seizures and induced easily detectable MR magnitude and phase changes concurrent with the spikes with a lag of milliseconds to tens of milliseconds. Due to the time scale of the responses, localized changes in blood flow or hemoglobin oxygenation are unlikely to cause the MR signal changes that we observed. While the precise underlying mechanisms are unclear, in this study, we empirically investigate one potentially important confounding variable — motion. Head motion in the scanner affects both EEG and MR recording. It can produce brief “spike-like” artifacts on EEG and induce large MR signal changes similar to our interictal spike-related signal changes. In order to explore the possibility that interictal spikes were associated with head motions (although such an association had never been reported), we had previously tracked head position in epilepsy patients during interictal spikes and explicitly demonstrated a lack of associated head motion. However, that study was performed outside the MR scanner, and the root-mean-square error in the head position measurement was 0.7 mm. The large inaccuracy in this measurement therefore did not definitively rule out motion as a possible signal generator. In this study, we instructed healthy subjects to make deliberate brief (<500 ms) head motions inside the MR scanner and imaged these head motions with concurrent EEG and MRI. We compared these artifactual MR and EEG data to genuine interictal spikes. While per-voxel MR and per-electrode EEG time courses for the motion case can mimic the corresponding time courses associated with a genuine interictal spike, head motion can be unambiguously differentiated from interictal spikes via scalp EEG potential maps. Motion induces widespread changes in scalp potential, whereas interictal spikes are localized and have a regional fall-off in amplitude. These findings make bulk head motion an unlikely generator of the large spike-related MR signal changes that we had observed. Further work is required to precisely identify the underlying mechanisms.     

MR imaging findings of infectious cholangitis

The purpose of this study was to evaluate the appearance of infectious cholangitis on MRI. The MR images of 13 patients (9 women, 4 men; age range, 14-79 years) with clinically confirmed infectious cholangitis, who represent our complete 9.5 year experience with this entity, were retrospectively evaluated. All MR studies were performed at 1.5 T and included: in-phase and out-of-phase T(1)-weighted spoiled gradient echo (SGE), T(2)-weighted fat-suppressed echo train spin echo, single shot T(2)-weighted sequences, and serial postgadolinium T(1)-weighted SGE sequences without and with fat-suppression. The biliary ductal system was evaluated regarding presence of dilatation, stenosis, wall irregularities, wall thickening, and gadolinium enhancement of duct walls. The liver parenchyma was evaluated regarding focal signal abnormalities on precontrast and serial postgadolinium images. Biliary ductal dilatation was observed in 100% of patients. Mild to moderate thickening of bile duct walls combined with increased enhancement on postgadolinium images was observed in 92% of patients. The liver parenchyma showed periportal or wedge-shaped areas of hyperintense signal on T(2)-weighted images in 69% of patients. On T(1)-weighted images, 54% of patients showed areas of hypointense signal and 15% of patients showed wedge-shaped hyperintense areas. Areas with increased enhancement on immediate postgadolinium SGE were observed in 58% of patients, and in 42% of patients increased enhancement persisted on 2 min postgadolinium fat-suppressed images. Distinctive MRI findings on pre- and postgadolinium images are appreciated for infectious cholangitis.     

Wavelet-based characterization of vertebral trabecular bone structure from magnetic resonance images at 3 T compared with micro-computed tomographic measurements

Trabecular bone structure and bone density contribute to the strength of bone and are important in the study of osteoporosis. Wavelets are a powerful tool in characterizing and quantifying texture in an image. The purpose of this study was to validate wavelets as a tool in computing trabecular bone thickness directly from gray-level images. To this end, eight cylindrical cores of vertebral trabecular bone were imaged using 3-T magnetic resonance imaging (MRI) and micro-computed tomography (microCT). Thickness measurements of the trabecular bone from the wavelet-based analysis were compared with standard 2D structural parameters analogous to bone histomorphometry (MR images) and direct 3D distance transformation methods (microCT images). Additionally, bone volume fraction was determined using each method. The average difference in trabecular thickness between the wavelet and standard methods was less than the size of 1 pixel size for both MRI and microCT analysis. A correlation (R) of .94 for microCT measurements and that of .52 for MRI were found for the bone volume fraction. Based on these results, we conclude that wavelet-based methods deliver results comparable with those from established MR histomorphometric measurements. Because the wavelet transform is more robust with respect to image noise and operates directly on gray-level images, it could be a powerful tool for computing structural bone parameters from MR images acquired using high resolution and thus limited signal scenarios.     

Texture analysis of magnetic resonance images of rat muscles during atrophy and regeneration

OBJECTIVES: The goals of the current study were (i) to introduce texture analysis on magnetic resonance imaging (MRI-TA) as a noninvasive method of muscle investigation that can discriminate three muscle conditions in rats; these are normal, atrophy and regeneration; and (ii) to show consistency between MRI-TA results and histological results of muscle type 2 fibers' cross-sectional area. METHOD: Twenty-three adult female Wistar rats were randomized into (i) control (C), (ii) immobilized (I) and (iii) recovering (R) groups. For the last two groups, the right hind limb calf muscles were immobilized against the abdomen for 14 days; then, the hind limb was remobilized only for the R group for 40 days. At the end of each experimental period, MRI was performed using 7-T magnet Bruker Avance DRX 300 (Bruker, Wissembourg); T1-weighted MRI acquisition parameters were applied to show predominantly muscle fibers. Rats were sacrificed, and the gastrocnemius muscle (GM) was excised immediately after imaging. (A) Histology: GM type 2 fibers (fast twitch) were selectively stained using the adenosine triphosphatase (ATPase) technique. The mean cross-sectional areas were compared between the three groups. (B) Image analysis: regions of interest (ROIs) were selected on GM MR images where statistical methods of texture analysis were applied followed by linear discriminant analysis (LDA) and classification. RESULTS: Histological analysis showed that the fibers' mean cross-sectional areas on GM transversal sections represented a significant statistical difference between I and C rats (ANOVA, P<.001) as well as between R and I rats (ANOVA, P<.01), but not between C and R rats. Similarly, MRI-TA on GM transversal images detected different texture for each group with the highest discrimination values (Fisher F coefficient) between the C and I groups, as well as between I and R groups. The lowest discrimination values were found between C and R groups. LDA showed three texture classes schematically separated. CONCLUSION: Quantitative results of MRI-TA were statistically consistent with histology. MRI-TA can be considered as a potentially interesting, reproducible and nondestructive method for muscle examination during atrophy and regeneration.     

Evaluation of discrete orthogonal versus polar Stockwell Transform for local multi-resolution texture analysis using brain MRI of multiple sclerosis patients

The Stockwell Transform has the potential to perform multi-resolution texture analysis in magnetic resonance imaging (MRI). However, it is computationally intensive and memory demanding. The polar Stockwell Transform (PST) is rotation-invariant and relatively memory efficient, but still computationally demanding. The new Discrete Orthogonal Stockwell Transform (DOST) appears to have addressed both the computation and storage challenges; however, its utility in localized texture analysis remains unclear. Our goal was to investigate the theory and texture analysis ability of the DOST versus PST using both synthetic and MR images, and explore the relative importance of the associated texture features using a simple classification example based on clinical brain MRI of six multiple sclerosis patients. MRI texture analysis focused on FLAIR images, and the classification used a machine learning algorithm, random forest, that differentiated regions of interest (ROIs) into 2 classes: white matter lesions, and the contralateral normal-appearing white matter (control). Our results showed that the PST features had a greater ability in detecting subtle changes in image structure than the DOST and polar-index DOST (PDOST). Quantitatively, based on 187 lesion and 187 control ROIs, both the PST and the rotation-invariant radial PST performed better in the classification than the DOST and PDOST, where the latter were no better than guessing (p = 0.65 and 0.98). Further analysis using a hierarchical random forest showed that combining MRI signal intensity with the PST or DOST predictions increased the classification performance, with the accuracy, sensitivity, and specificity all improved to >85% in the tests. Collectively, the DOST is less competitive than the PST in localized image texture analysis. The PST features may help with texture-based lesion classification in MS based on clinical brain MRI scans following further verification.     

Investigations and Modeling of the Effect of Magnetic Nanoparticles on MR Image Contrast

The investigations of nuclear magnetic resonance (NMR) relaxation of protons in aqueous solution and 2% agar–agar gel in the presence of magnetic nanoparticles were performed. To identify the effect of magnetic nanoparticles on the contrast of magnetic resonance images, the dependences of the MR signal intensity on the parameters of the two pulse radio-frequency (RF) sequences (spin-echo, gradient-echo) most commonly used in MRI for different values of the magnetic nanoparticle (MNP) concentration were simulated and analyzed. Recommendations for choosing the optimal values of pulse RF sequence parameters for MR imaging (MRI) in the presence of MNPs are formulated. MRI studies of phantom samples with 2% agar–agar gel containing MNPs have been performed for choosing the fast pulse RF sequence which shows the greatest contrast effect on MR images. A program for modeling magnetic resonance tomograms and determination of optimal values of pulse RF sequence parameters to achieve the best contrast of magnetic resonance images is developed. This program allows to reduce the time of MRI studies, to assess the possibility of using MNPs for contrast of MR images and to simulate the MR image in the presence of magnetic nanoparticles at the planning stage of procedures in MR-guided theranostics.     

Composite and classified color display in MR imaging of the female pelvis.

Because of its superior soft-tissue-imaging capabilities, MRI has proved to be an excellent modality for visualizing the contents of the female pelvis. In an effort to potentially improve gynecological MRI studies, we have applied color composite techniques to sets of spin-echo and gradient-echo gray-tone MR images obtained from various individuals. For composite generation, based on tissue region of interest calculated mean pixel intensity values, various colors were applied to spatially aligned images using a DEC MicroVAX II computer with interactive digital language (IDL) so that tissue contrast patterns could be optimized in the final image. The IDL procedures, which are similar to those used in NASA's LANDSAT image processing system, allowed the generation of single composite images displaying the combined information present in a series of spatially aligned images acquired using different pulse sequences. With our composite generation techniques, it was possible to generate seminatural-appearing color images of the female pelvis that possessed enhanced conspicuity of specific tissues and fluids. For comparison with color composites, classified images were also generated based on computer recognition and statistical separation of distinct tissue intensity patterns in an image set using the maximum likelihood processing algorithm.