Neoplastic vs inflammatory meningeal enhancement with Gd-DTPA

We studied 40 consecutive patients clinically suspected of having meningeal disease, in whom both Gd-diethylenetriamine pentaacetic acid (DTPA)-enhanced magnetic resonance (MR) examinations and CSF or surgical pathologic samples were obtained. The MR examinations were retrospectively reviewed for the presence of abnormal meningeal enhancement, as well as pattern and site of enhancement. The MR findings correctly correlated with pathology results in 15 of 19 patients with suspected tumor involvement (including one true negative) and in 18 of 21 patients with suspected inflammatory meningeal conditions (including 2 true negatives). Pial enhancement was demonstrated in 62% (10 of 16) of patients with meningitis and in 29% (4 of 14) of patients with meningeal neoplastic involvement. A diffuse meningeal distribution was commonly present with inflammatory conditions (69%, 11 of 16). A nodular appearance was seen in two patients with tumor involvement of the meninges as well as in a single case of sarcoidosis but was not seen with infectious meningitis. Our data suggest that Gd-DTPA-enhanced MR imaging is sensitive to the presence of meningeal pathology but is nonspecific as to disease entity. Recognition of certain MR patterns in conjunction with clinical presentation may improve diagnosis and management of patients with suspected meningeal disease.     

Benign extraaxial tumors: contrast enhancement with Gd-DTPA

Meningiomas, acoustic neuromas, and other benign extraaxial tumors have little contrast with adjacent brain tissue on conventional magnetic resonance (MR) images. The contrast enhancement produced by intravenous administration of 0.1 mmol/kg of gadolinium-DTPA in these tumors was measured on T1 MR images. Acoustic neuromas showed the greatest enhancement (average, 310%), meningiomas the next greatest (average, 180%), and neurofibromas, glomus tumors, and pituitary microadenomas the least enhancement. The degree of enhancement was almost always greater at 3 minutes than at 25 or 55 minutes. Contrast between the tumor and adjacent tissue resulted from tumor enhancement in neuromas, meningiomas, and neurofibromas and from enhancement of the surrounding tissue in pituitary microadenomas.     

MR contrast enhancement of intracranial lesions with Gd-DTPA

Gd-DTPA is a paramagnetic contrast agent for MR that produces enhancement of lesions on T1-weighted images. Since it does not cross the intact blood-brain barrier (BBB), Gd-DTPA enhances only those pathologic processes that are associated with breakdown of the BBB and structures or lesions that are devoid of a BBB. Gd-DTPA improves conspicuity, helps characterize and delineate the extent of lesions, and increases the sensitivity for detection of cerebral abnormalities.     

三倍量(0.3mmol/kg)国产Gd-DTPA增强MR探查脑膜转移瘤的研究

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Breast disease: tissue characterization with Gd-DTPA enhancement profiles

Magnetic resonance (MR) imaging of the breast is currently of limited value because of lack of specificity. Enhanced MR imaging with gadolinium diethylenetriaminepentaacetic acid (DTPA) has been shown to be helpful in the further characterization of breast tissue. This prospective study attempted to differentiate benign and malignant breast disease with a dynamic enhancement technique. Bolus injection of Gd-DTPA and a short MR imaging time were used to examine 18 patients with a palpable breast mass. Construction of enhancement profiles helped effectively differentiate benign and malignant lesion (P less than .001). Dynamic MR imaging shows promise for the further characterization of breast tissue and, particularly, identification of breast carcinoma.     

Correlation between choline level and Gd-DTPA enhancement in patients with brain metastases of mammary carcinoma

Single voxel ¹HH double spin-echo MR spectroscopy was used to examine 15 cases of brain metastasis of mammary carcinoma (18 lesions) in relation to Gd-DTPA enhanced MR imaging. For lesions larger than 50% of MRS voxel size, there was significant correlation between Gd-DTPA-enhanced MRI signal and MRS-detected signal of choline (Cho) containing compounds (r = 0.86, P < 0.01; n = 8). The observed loss of correlation when including the smaller lesions was overcome by correcting for partial volume effects (r = 0.69, P < 0.002; n = 18). Metastasis spectra showed increased Cho compared with control spectra, except for those lesions showing detectable lactate (Lact) signal. The detection of Lact in four of the larger lesions coincided with comparatively low levels of creatine (Cr) and Cho and heterogeneous Gd-DTPA enhancement (ring-enhancement). It was concluded that in brain metastases of mammary carcinoma Lact represents a product of ischemia preceding/during tissue decay resulting in central necrosis, rather than tumor specific metabolism resulting in increased glycolysis.     

Acoustic neuromas: Gd-DTPA enhancement in MR imaging

Magnetic resonance (MR) imaging examinations were performed in ten patients with 12 acoustic neuromas before and after intravenous administration of 0.1 mmol/kg body weight gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). The degree of enhancement was greatest with the inversion recovery sequence 1,500/500/44 (repetition time [TR]/inversion time/echo delay time [TE]), followed by spin-echo (SE) 544/44 (TR/TE) sequences, then by SE 1,500/44 and SE 1,500/80 sequences. After enhancement there was a 50% reduction for measured T1 values, 33% for T2, and no significant change for proton density. There were no toxic effects on patients. Enhanced CT scans failed to demonstrate lesions in six of 12 cases. Air-CT technique improved sensitivity in four of five cases. Enhanced MR imaging added significant clinical information in two small intracanalicular tumors and in one recurrent tumor.     

Synergistic enhancement of MRI with Gd-DTPA and magnetization transfer.

Magnetization transfer (MT) between protons of macromolecules and protons of water molecules is a recently introduced mechanism for tissue contrast in MR imaging. The MT effect is strong in tissues where there is an efficient cross relaxation between macromolecular protons and water protons and where this interaction is the dominant source of relaxation. Paramagnetic ions shorten relaxation times and decrease the MT effect. These two facts led to the assumption that, in the case of contrast enhanced MRI, the combination of the T1-weighted imaging method and the MT technique may yield increased contrast, compared with standard methods. The synergistic effect is demonstrated in this work with studies of egg white samples and by imaging three patients with different brain pathologies. The lesion-to-white matter contrasts, with standard T1-weighted sequences with and without the MT effect, were compared before and after the introduction of Gd-DTPA. In each case the synergistic effect of T1 weighting and MT improved the contrast enhancement provided with Gd-diethylenetriamine pentaacetic acid.     

MR fat suppression combined with Gd-DTPA enhancement in optic neuritis and perineuritis

A fat suppression MR technique used in combination with Gd-DTPA enhancement was investigated to determine its value in cases of inflammatory optic nerve lesions. This technique, the so-called hybrid method, is a derivative of the chopper fat suppression technique and provides water-only images without increasing the imaging or postprocessing time. The study group consisted of four patients with acute visual loss, all of whom received Gd-DTPA. Conventional T2-weighted and fat suppression post-Gd-DTPA T1-weighted images were obtained in all patients; in addition, in one patient a post-Gd-DTPA T1-weighted image without fat suppression was obtained. In three patients, the conventional T2-weighted images failed to reveal any abnormality. In contrast, the enhanced optic nerve and enhanced perineural inflammatory infiltrate were easily identified on T1-weighted images after administration of Gd-DTPA and application of fat suppression technique. The lesions in inflammatory optic neuritis or perineuritis were easily distinguished from the surrounding fat, which had been suppressed. This combined technique resulted in significantly improved definition of normal anatomic structures and made the enhancing lesions more conspicuous, especially in areas with large amounts of fat such as the retrobulbar orbit.     

Cerebral Erdheim-Chester disease: persistent enhancement with Gd-DTPA on MR images

A case of Erdheim-Chester disease with intracerebral masses containing characteristic lipid-laden histiocytes is presented. These unusual lesions remained enhanced on magnetic resonance images obtained 8 days after injection of gadolinium diethylenetriaminepentaacetic acid (DTPA) dimeglumine. Chemical analysis of a biopsy specimen revealed a high concentration of gadolinium. Findings suggest that the Gd-DTPA complex or possibly a gadolinium-containing metabolite may be retained for extended periods in this unusual type of histiocytic lesion.     

In vivo fluorine-19 MR imaging: Relaxation enhancement with Gd-DTPA

The lack of a naturally occurring background signal from fluorine in magnetic resonance (MR) imaging makes fluorinated compounds potentially attractive candidates for tissue-specific MR contrast agents. Problems associated with the in vivo use of fluorinated compounds are toxicity, which limits the amount of agent that can be used; multiple resonance lines; and an excessively long T1, which leads to long sequence TRs and consequently long imaging times. Many fluorinated agents also possess complex MR spectra that result in chemical shift artifacts if not corrected. The authors demonstrate the use of an extracellular fluorinated agent with a single MR peak for selective imaging of a brain abscess in an animal model and show that the image signal per unit of acquisition time can be enhanced through the use of a T1 relaxation agent, gadolinium diethylenetriamine-pentaacetic acid (DTPA). Trifluoromethylsulfonate was administered at a fluorine-19 dose of 4 mmol/kg, and fluorine images of the induced abscess were acquired before and after the injection of a standard dose of Gd-DTPA (0.1 mmol/kg); non—section-selected projection images were used. Typical imaging times were less than 5 minutes. The signal enhancement factor achieved was approximately four (4.0 ± 0.8) with use of a 500/12 (TR msec/TE msec) spinecho sequence.     

MR Gd-DTPA enhancement of radiation brain injury.

MR examinations of 104 patients who had undergone radiotherapy to the brain were reviewed. Thirty-six patients received Gd-DTPA enhanced study during the course of MR evaluation and six of the patients showed enhancing radiation necrosis. Histopathological confirmations were obtained in three patients. Gd-DTPA enhancing radiation lesions were multiple and patchy in three patients, multiple and patchy with cyst formation in two and ring shaped in one. In terms of their distribution, enhancing lesions in four patients were seen only in the white matter within the irradiated field and these patients had undergone radiotherapy within five years. The interval after radiotherapy was more than eight years in two patients and their enhanced lesions were observed in both the white and gray matter. Histopathological findings of Gd-DTPA enhancing radiation necrosis were gliosis and coalescing vacuoles of the neural tissue. None of these enhanced radiation lesions showed significant mass effects. Patterns of the enhancement were not specific. It was considered to be difficult to differentiate tumor recurrence from radiation necrosis with conventional Gd-DTPA enhanced MR examinations. In one patient, delayed MR images after Gd-DTPA administration showed increases in the size and number of radiation enhanced lesions. Dynamic and delayed MR study might add more information to conventional imaging after Gd-DTPA. Further studies are necessary to differentiate radiation lesions from tumor recurrences.     

Gd-DTPA enhanced MR for detecting intracranial extension of sinonasal malignancies

Magnetic resonance imaging is frequently used for evaluating the extent of malignant tumor in the paranasal sinuses and nasal fossa. Detection of the intracranial extension of a tumor is important in the initial staging of disease. The epidural component of a sinonasal tumor frequently displays signal intensity at or near that of the adjacent brain on standard T1- and T2-weighted scanning sequences. In six of eight malignant sinonasal tumors with intracranial involvement, gadopentetate dimeglumine (Gd-DTPA) enhanced MR was significantly better than the noncontrast scans for demonstrating the intracranial extension. This finding is in contradistinction to the superiority of unenhanced T2-weighted scans for determining the extent of disease within the sinonasal region itself. Tangential Gd-DTPA MR scanning of the skull base compensates for the difficulty of recognizing areas of bone destruction on noncontrast images. Postcontrast sequences should be added to the scanning protocol for sinonasal lesions near the skull base.     

Acute experimental cerebral ischemia: MR enhancement using Gd-DTPA

The effects of a paramagnetic contrast agent, gadolinium-DTPA (Gd-DTPA), on magnetic resonance (MR) imaging of acute cerebral ischemia was investigated in a feline model of middle cerebral artery occlusion. Imaging was performed both before and after administration of an intravenous dose of 0.2 mmol/kg of Gd-DTPA. The animals were then sacrificed for pathologic correlation. No changes in intensity or relaxation times were noted before or after Gd-DTPA administration in two animals with 2 hours of occlusion. Infarcts were noted before and after contrast enhancement in all six cats with ischemia of greater than 16-hours duration. Gd-DTPA caused significant increase in intensity of infarct but not in that of normal cerebral tissue. Rapid enhancement was visible in infarcts of 16-24 hours, but such enhancement was slower in infarcts of 72-168 hours, presumably owing to slowed inflow caused by increased vasogenic edema in the latter group. Contrast enhancement of acute cerebral ischemic lesions with Gd-DTPA offers no improvement in sensitivity of MR imaging, although the conspicuity of the lesion may be improved. Additionally, contrast media may provide potential temporal and pathophysiological data for better characterization of cerebral ischemia.     

A case of cervical juxtafacet cyst with extensive rim enhancement on Gd-DTPA MRI

The authors reported a case of cervical juxtafacet cyst with extensive rim enhancement on gadolinium-diethylenetriamine pentaacid magnetic resonance imaging. Operative finding revealed the epidural space around the mass filled with abundant venous plexus. Histological examination demonstrated that cyst wall was composed of the well-vascularized fibrous connective tissue with some inflammatory changes. We speculate that extensive rim enhancement of juxtafacet cyst may be attributed not only to the chronic inflammatory changes of cyst wall, but to engorged venous plexus within the widened epidural space.