T2-weighted MR Research Articles

US, CT and MR imaging characteristics of nephroblastomatosis.

To describe the imaging features of nephroblastomatosis with US, CT and MR, to point out characteristics of differentiation between nephrogenic rests (NR) and Wilms' tumour (WT) and to determine the most appropriate imaging modality. We reviewed the US, CT and MR images of 29 cases of histopathologically confirmed nephroblastomatosis sent to our department for reference evaluation (German nephroblastoma study). The series included 17 kidneys with NR, 6 kidneys with WT and 32 kidneys with both NR and WT. NR presented as multinodular, peripheral, cortical lesions, the diffuse form of distribution being less common. Foci were homogeneous and of low echogenicity, density or signal intensity. The lesions were most clearly depicted with contrast-enhanced CT and T1-weighted (T1-W) MR images. Lesions smaller than 1 cm were rarely identified by US. The most reliable criterion to differentiate NR from WT was their homogeneity. Contrast-enhanced CT and T1-W MR images are of similar potential and superior to US in the diagnosis of nephroblastomatosis. Due to the significant radiation dose of serial CT, MR imaging should be the method of choice wherever it is available. The cost-effectiveness and availability of US makes it ideal for serial follow-up of known lesions.

Carcinoma of the cervix: Value of dynamic magnetic resonance imaging in assessing early stromal invasion

The purpose of this study was to assess the accuracy of contrast-enhanced magnetic resonance imaging (dynamic MR imaging) in the evaluation of preinvasive and early invasive cancer of the cervix. Twenty-nine women with untreated squamous cell carcinoma of the cervix with either no stromal invasion or early stromal invasion underwent pretreatment MR imaging and dynamic MR imaging within 4 weeks of surgical evaluation. The images were evaluated for tumor detection and compared with results of histologic examination of the surgical specimens. The lesions in 17 cases with histologically proven stromal invasion of 4 mm or greater were detected with dynamic MR imaging, whereas lesions in only 8 of these cases were detected with T2 imaging. In 9 cases with stromal invasion between 4.0 mm and 5.0 mm, lesions were represented as early phase focal enhancement on dynamic MR images, but not detected on T2-weighted images. In the 12 cases with less than 4 mm stromal invasion, no lesions were visualized on either T2-weighted images or dynamic MR images, except in 1 case of glandular involvement without stromal invasion that appeared as enhancement on early-phase dynamic MR imaging. Dynamic MR imaging detected more lesions of early stromal invasion in pretreatment imaging for cervical cancer than nonenhanced MR imaging.

Imaging of Puerperal Septic Thrombophlebitis

Our objective was to compare prospectively the abilities of MR imaging, CT, and sonography to reveal puerperal septic thrombophlebitis in the pelvis.Seventy-six women with puerperal fever for 5 days refractory to antimicrobial therapy underwent MR imaging, CT, and sonography. We obtained unenhanced axial CT images followed by enhanced images after the administration of an oral contrast agent for which we followed a specific protocol. Axial T1- and T2-weighted spin-echo MR images with phase reconstruction and sagittal T1-weighted MR images were obtained. Real-time sonography was performed using Doppler color flow mapping and spectral waveform analysis.Of the 76 women, 64 completed studies with all three techniques. Ovarian vein thrombosis was diagnosed in 12 women. True-positive results were indicated when at least two of the three studies showed the presence of a clot; true-negative results were indicated when at least two of the three studies showed a lack of thrombosis. MR imaging and CT revealed both o...

Assessment of depth of myometrial invasion by endometrial carcinoma: comparison of T2-weighted SE and contrast-enhanced dynamic GRE MR imaging

A prospective study was undertaken to assess the value of both T2-weighted spin-echo (SE) and contrast-enhanced dynamic gradient-echo (GRE) sequences using MR imaging in differentiating the deep myometrial invasion from lower stages produced by endometrial carcinoma. For the correlation of MR findings with the histopathologic findings, patients who had no myometrial invasion (stage 1 a) and patients in whom tumors were confined to the superficial myometrium (stage 1 b) at pathologic examination were combined as lower stages. Twenty patients with endometrial carcinoma were studied using both techniques. The absence of any detectable tumor (stage 1 a) or the presence of a tumor confined to inner half of myometrium (stage 1 b) and extention of tumor to the outer half of myometrium (stage 1 c) were used as the diagnostic criteria. In pathologic examination of excised specimens, deep myometrial invasion was detected in 9 of 20 patients. The sensitivity, specificity, accuracy, positive predictive values (PPV) and negative predictive values (NPV) of T2-weighted SE in differentiating deep myometrial invasion from combined lower stages were 88, 91, 90, 88, and 91 %, respectively, whereas corresponding values for contrast-enhanced dynamic GRE sequences were 78, 100, 90, 100, and 85 %. Statistical difference between two sequences did not reach a significant level. We conclude that in cases of absence of visible junctional zone with SE sequence, contrast-enhanced dynamic GRE MR imaging may be helpful.

Langerhans cell histiocytosis in the mandible: Computed tomography and magnetic resonance imaging

Langerhans cell histiocytosis in the mandible is a rare disease. The clinical and advanced imaging features of Langerhans cell histiocytosis in an 18-year-old male are presented. CT images showed an diffuse, ill-defined, expansile lesion of heterogeneous density extending from the anterior mandibular area to the right molar area. CT was particularly helpful in confirming a cortical invasion. T1-weighted gradient echo MR images revealed a heterogeneously low-to high-signal intensity lesion in the right side of the mandible. T2-weighted spin echo MR images showed a heterogeneously iso-to high-signal intensity area with low-intensity areas. Multidirectional MR images revealed the extent of the lesion in the mandibular bone marrow more clearly than CT.

The Fatty Disc: An Unusual Cause of Bright Intervertebral Disc on T1-Weighted Conventional Spin-Echo MR: A Case Report

A hyperintense intervertebral disc on T1-weighted spin-echo MR image, the “bright disc”, is described in a patient with a long-standing ankylosing spondylitis. The high signal intensity was due to the fatty infiltration of the discal tissue, as was clearly demonstrated by the comparison of MR and CT scan of the lumbar spine, probably due to progressive endochondral ossification with subsequent bone marrow metaplasia in the ossified disc.

MRI of bowel obstruction using the HASTE sequence.

High quality MR images of the gastrointestinal tract are now obtainable using a T2-weighted fast SE MR sequence with half-Fourier acquisition of data (the HASTE sequence). This fast sequence can acquire a set of images in a single breath hold and is insensitive to peristalsis-related artifact. It can be used with other imaging modalities in defining bowel obstruction and is accurate in determining the presence of bowel dilation and level of obstruction and in differentiating obstructing tumor from other causes of obstruction.

Neuroradiologic MR applications with multiparametric color composite display

The purpose of this article is to demonstrate the application of a PC-based multiparameter full color composite display technique of MR images of 14 selected patients with neuropathology while assessing the ability of this technique to display clinically important neuroanatomic and neuropathologic tissues. Using a PC with a 386 microprocessor and full color 24-bit graphics display capabilities, custom and commercially available image-processing softwares were applied to spatially aligned multiparameter proton density, T1-weighted (with and/or without gadolinium-DTPA) and T2-weighted MR image sets obtained from 14 patients with known neuropathology to generate intensity-based color composites. Quantitative color channel applications were used to assess the ability of this technique to differentiate anatomically and pathologically confirmed tissue types into unique color regions within the full color spectrum display in each patient case. Based on the results of pathologic correlation and quantitative color imaging analysis, the application of full color composite generation techniques to multiple MR images of selected neuropathology cases represents a viable technique for displaying diagnostically relevant tissue contrast information in one color image. With this technique, it is possible to generate composites that simultaneously display uniquely color-coded neuroanatomic and neuropathologic tissue information within the context of partially natural-appearing images.

Inflammatory pseudotumor of the maxillary sinus: CT and MR findings in six cases.

Inflammatory pseudotumor is a chronic inflammatory lesion of unknown origin. The purpose of this study was to analyze the CT and MR findings in six cases of inflammatory pseudotumor of the maxillary sinus in order to determine if there were any imaging findings that distinguish this lesion from the more common type of pseudotumor that occurs in the orbit. Six patients with pseudotumor of the maxillary sinus were identified retrospectively. The diagnosis was based on biopsy specimens. Their CT scans and MR images were studied by two radiologists to identify specifically the presence of soft-tissue disease and the presence and type of any bone involvement. CT and MR images showed some degree of involvement of the bony wall in all cases. All patients had a soft-tissue mass with mild enhancement on CT scans and intermediate signal intensity on both T1- and T2-weighted MR images. Our experience shows that inflammatory pseudotumor of the maxillary sinus causes bone changes on CT and MR images, findings that mimic a malignant tumor. Bone involvement appears to be more common in pseudotumor of the maxillary antrum than in its orbital counterpart.

Dynamic Gadolinium-Enhanced Mr Imaging in Active and Inactive Immunoinflammatory Gonarthritis

Dynamic T1-weighted FLASH MR imaging, obtained just after i.v. gadopentetate dimeglumine injection, and pre- and postcontrast T1-weighted spin-echo (T1-SE) MR imaging were performed to compare their information value with respect to inflammatory activity in immunoinflammatory gonarthritis. We examined 16 clinically active (CAG), 7 clinically inactive (CIG) and 4 healthy knees. The synovium of a preselected slice was outlined. Its area and relative signal intensity increase after gadopentetate dimeglumine on T1-SE and FLASH (at each time t) were calculated. The CAG knees showed a mean signal intensity increase on early dynamic FLASH images higher by far than the CIG knees, while no significant difference was found on spin-echo images obtained 5 to 15 min after contrast injection. The early signal enhancement probably reflects the perfusion and capillary permeability of the synovium. The area of synovium could differentiate between healthy and arthritic knees. Gadolinium-enhanced dynamic FLASH imaging may provide clinically useful information about the actual inflammatory activity of arthritic joints.

Dynamic gadolinium-enhanced MR imaging in active and inactive immunoinflammatory gonarthritis

Dynamic T1-weighted FLASH MR imaging, obtained just after i.v. gadopentetate dimeglumine injection, and pre- and postcontrast T1-weighted spin-echo (T1-SE) MR imaging were performed to compare their information value with respect to inflammatory activity in immunoinflammatory gonarthritis. We examined 16 clinically active (CAG), 7 clinically inactive (CIG) and 4 healthy knees. The synovium of a preselected slice was outlined. Its area and relative signal intensity increase after gadopentetate dimeglumine on T1-SE and FLASH (at each time t) were calculated. The CAG knees showed a mean signal intensity increase on early dynamic FLASH images higher by far than the CIG knees, while no significant difference was found on spin-echo images obtained 5 to 15 min after contrast injection. The early signal enhancement probably reflects the perfusion and capillary permeability of the synovium. The area of synovium could differentiate between healthy and arthritic knees. Gadolinium-enhanced dynamic FLASH imaging may provide clinically useful information about the actual inflammatory activity of arthritic joints.

Graphical analysis of MR feature space for measurement of CSF, gray-matter, and white-matter volumes.

The problem of volume averaging in quantitating CSF, gray-matter, and white-matter fractions in the brain is solved using a three-compartment model and a simple graphical analysis of a multispectral MR feature space. Compartmentalization is achieved without the ambiguities of thresholding techniques or the need to assume that the underlying pixel probability distributions have a particular form. A 2D feature space is formed by double SE (proton density- and T2-weighted) MR data with image nonuniformity removed by a novel technique in which the brain itself serves as a uniformity reference. Compartments other than the basic three were rejected by the tailoring of limits in feature space. Phantom scans substantiate this approach, and the importance of the careful selection and standardization of pure tissue reference signals is demonstrated. Compartmental profiles from standardized subvolumes of three normal brains, based on a 3D (Talairach) coordinate system, demonstrate slice-by-slice detail; longitudinal studies confirm reproducibility. Compartmentalization may be described graphically and algebraically, complementing data displays in feature space and images of compartmentalized brain scans. These studies anticipate the application of our compartmentalization technique to patients with neurological disorders.

Normal anatomy of the hippocampus and adjacent temporal lobe: high-resolution fast spin-echo MR images in volunteers correlated with cadaveric histologic sections.

This essay illustrates the appearances of sections of the normal hippocampus and adjacent temporal lobe on high-resolution heavily T2-weighted fast spin-echo MR images and correlates them with histologic sections. We found that this MR examination showed the detailed anatomy of the normal hippocampus in a much shorter time than is possible with conventional spin-echo techniques. The information provided in this essay can be used as a baseline for distinguishing between normal and abnormal hippocampi in a variety of disease states.

Prä- und postoperative kernspintomographische Untersuchungen bei avaskulären Hüftkopfnekrosen

46 patients with avascular necrosis of the femoral head were examined by T2- and T1-weighted MR before and after infusion of Gd-DTPA. Both sides were involved in 12 cases. The classification was done according to Ficat. In early stages and in postoperative studies a correlation of signal intensity after infusion of Gd-DTPA and clinical symptoms was found. Hyperintensity of the avascular area or of the implanted material was assumed to be vascularised or vital components in 4 cases of Ficat I and in 15 postoperative studies. Contrariwise, we found in 5 patients with severe postoperative symptoms, low signal intensity areas due to avascular regions.

Magnetic resonance imaging of retracted and nonretracted blood clots during fibrinolysis in vitro.

Magnetic resonance imaging (MRI) of retracted blood clots embedded in nonretracted clots was used to follow their lysis with urokinase in a plasma milieu in vitro. The two types of clots that were imaged in the same plane differed in signal intensity on T2-weighted spin echo MR images throughout the 20-hour observation period. It was thus possible to delineate the contours of both clot types and measure their relative sizes by digital image processing. Lysis of retracted clots proceeded significantly slower than lysis of nonretracted clots. Our in vitro results suggest that MRI might prove useful in detecting thrombus retraction in vivo and in predicting the outcome of thrombolytic therapy.

MR Imaging of Middle Ear Cholesteatomas

We prospectively evaluated MR images of 14 patients who had chronic otitis media and who were suspected of having cholesteatomas on otologic examination and/or on high resolution CT. Cholesteatomas were verified in the middle ear and/or mastoid at surgery in nine patients. Cholesteatomas appeared isointense relative to gray matter on T1-weighted spin echo MR images (T1WI) and hyperintense on T2-weighted spin echo MR images (T2WI) in eight patients. Two cholesterol granulomas appeared hyperintense on both T1WI and T2WI. In three patients with chronic otitis media the associated mixed granulation tissue and fluid collection was revealed as nonspecific, heterogeneous signal intensity in two cases. In the third case the signal intensity was similar to that found in cholesteatomas.

Chronic Osteomyelitis with Epidural Abscess

A case of chronic osteomyelitis in the occipital bone associated with underlying chronic epidural abscess was diagnosed by skull radiography, CT, and MR. Skull radiography showed diffuse sclerosis of the occipital bone and dural calcifications. Computed tomography demonstrated thickened sclerotic changes of the osteomyelitic area, dural calcifications, and epidural fluid collection. The area of chronic osteomyelitis displayed, essentially, no signal intensity in the T1-weighted and T2-weighted MR images. The chronic epidural abscess had heterogeneous signal intensity on T1-weighted images and good enhancement after Gd-diethylenetriamine pentaacetic acid administration. On T2-weighted images the abscess had relatively homogeneous high signal intensity.

Kernspintomographische Differenzierung von Augenmuskelveränderungen bei endokriner Orbitopathie

In 50 patients with Graves' Ophthalmopathy and 9 controls both orbits were examined by MR Imaging at 0.5 Tesla using a surface coil. T1-weighted spin-echo images were obtained in transverse and coronal orientation; additionally, a T2-image was calculated from a multi-echo sequence (8 echoes). Signal intensity of eye muscles on both T1-weighted and T2-weighted MR images was evaluated qualitatively. T2-times were then calculated for all inferior rectus muscles. Eye muscle enlargement was found in 28 out of 50 patients. T2-times of inferior rectus muscles in stage III and IV patients were evaluated significantly (p less than 0.05). Areas of high signal intensity were accordingly found in enlarged eye muscles in 19 out of 50 patients; they were interpreted as edematous tissue changes. Areas of low signal intensity were found in enlarged eye muscles of 5 out of 50 patients; these eye muscles were considered fibrotic. Differentiation of eye muscle changes by MR imaging might help to decide between antiinflammatory medication and surgical therapy in patients with Graves' Ophthalmopathy.

Pelizaeus-Merzbacher disease: identification of heterozygotes with magnetic resonance imaging?

We report magnetic resonance imaging (MRI) findings in two obligate and four facultative carriers for the "classical" X-linked form of Pelizaeus-Merzbacher disease (PMD). In T2-weighted images MR revealed bilateral multiple areas with signal hyperintensity in the periventricular and subcortical white matter in five women. Until suitable and closely linked DNA probes are found for heterozygote determination, MRI may represent a suitable means for carrier detection in individuals at risk in PMD families.