Tumors of the nasopharynx and adjacent areas: MR imaging with Gd-DTPA

The purpose of this study was to describe our experience with Gd-DTPA-enhanced MR imaging in the evaluation of the most common nasopharyngeal tumors. Forty-two patients with tumors of the nasopharynx and adjacent spaces had MR imaging before and after IV injection of Gd-DTPA. Images were obtained with a 1.0-T superconducting magnet imaging system in transverse, coronal, and sagittal planes with T1- and T2-weighted sequences. MR images were compared with CT scans and tumor histology. The studies were categorized by using a grading system with grades ranging from unsatisfactory (grade 0) to optimal (grade 3). Contrast-enhanced MR enables better identification of small anatomic details such as both palatini muscles and the pharyngobasilar fascia. MR after Gd-DTPA was superior to CT in all cases except for tumors of the maxillary sinuses. MR with Gd-DTPA is recommended for tumors that are small and difficult to detect on the initial nonenhanced MR examination or that show subtle infiltrations. Because of the increased cost and longer examination time, MR with Gd-DTPA does not need to be done when large tumors are well delineated.     

Metastatic liver tumor from cystic ovarian carcinomas: CT and MRI appearance.

OBJECTIVE: The initial and follow-up CT and MRI images of ten patients with hepatic metastases from ovarian tumors were retrospectively analyzed to establish their features and sequential changes in appearance. MATERIALS AND METHODS: Ten patients with hepatic metastasis from ovarian tumors received initial and follow-up CT and MRI examinations. Six patients were followed up every two to three weeks before surgical tumor resection. Both CT and MR images were analyzed by two radiologists. RESULTS: A total of fourteen lesions were detected by CT and MRI in 10 patients. All 14 lesions were demonstrated as areas of marked hyperintensity on T2-weighted MRI. Eleven cyst-like tumors were demonstrated as round or oval low density lesions on CT and as areas of hypointensity on T1-weighted imaging. Three lesions were shown as solid masses with slightly low attenuation at the initial CT examination and slightly low or iso-intensity areas on T1-weighted imaging, and these lesions showed early peripheral globular enhancement and delayed enhancement on contrast-enhanced CT and MR imaging. Cystic formation was observed two to three weeks later after initial study in all the 3 solid lesions. Rapid subcapsular effusion, which showed obvious enhancement on delayed Gd-DTPA enhanced MR imaging, was observed in two patients. CONCLUSION: The hepatic metastatic tumor from cystic ovarian carcinoma may manifest as a well-defined cystic lesion or as a solid mass, and the solid mass shows delayed enhancement on contrast-enhanced CT and MR imaging. Furthermore, rapid cystic formation and rapid subcapsular extension is frequently seen.     

MR imaging of primary bone and soft tissue tumors

MR imaging of 131 cases with pathologically confirmed primary bone and soft tissue tumors were studied. They included 44 bone tumors (25 benign tumors, 19 malignant tumors) and 87 soft tissue tumors (55 benign tumors, 32 malignant tumors). MR imaging was performed on 0.5T, superconductive magnet system. All tumors were evaluated with T1-weighted, T2-weighted and STIR images. In some cases, contrast enhanced MR imaging with Gd-DTPA was applied. MR imaging was proving to be a valuable technique in the evaluation of patients with primary bone and soft tissue tumors. MR imaging was superior to the other modalities in delineating the extent of the tumor and their relation to surrounding structures in all cases. However, plain radiography and CT were more useful for evaluation of calcification, ossification, cortical destruction and endosteal/periosteal reaction than MR imaging. Direct sagittal and coronal images from MR imaging added accurate assessment for the relation between the tumor and their adjacent structures. MR imaging was of limited value in distinguishing benign from malignant tumors with the demonstration of tumor structures only, especially soft tissue tumors. But in bone and soft tissue tumors which have specific morphologic features and intensity patterns, MR imaging was very useful for diagnosis.     

Experimental intracranial septic infarction: magnetic resonance enhancement

Intracranial brain abscess was produced in three monkeys by embolization of a small pledget of polyvinyl alcohol (PVA) soaked in a broth of Staphylococcus aureus. Imaging of the chronic stable abscess was performed on the General Electric 8800 CT unit (Milwaukee, Wis.) and a 1.4 T superconducting small bore imaging system. Magnetic resonance imaging included saturation recovery, inversion recovery, and spin echo techniques. MR imaging was also performed after paramagnetic enhancement using gadolinium-DPTA (Gd-DTPA). Our results show that paramagnetic enhancement with T1-weighted imaging adds specificity and enables rapid assessment of abnormalities of the blood-brain barrier. T2-weighted imaging without paramagnetic enhancement was very sensitive in defining areas of abnormality in the brain but in our experiment lacked specificity. T2-weighted imaging with Gd-DTPA demonstrated no obvious change in the appearance of the lesion. The combination of T1-weighted Gd-DTPA and T2-weighted imaging appeared complementary in our experiment, and these images correlated well with the pathologic findings.     

Gd-DTPA-enhanced MR imaging in pediatric patients after brain tumor resection

A prospective study was conducted in 15 pediatric patients who had undergone resection of intracranial tumors. The object of the study was to determine the safety and efficacy of magnetic resonance (MR) imaging performed after the administration of gadolinium diethylenetriamine-pentaacetic acid (Gd-DTPA) in evaluating residual or recurrent tumor. Precontrast T1-weighted, intermediate, and T2-weighted images were obtained at a field strength of 1.5 T. Gd-DTPA was then injected intravenously in a dose of 0.1 mmol per kilogram of body weight. T1-weighted images were obtained within 5 minutes after the injection, intermediate and T2-weighted images were obtained 10 minutes after the injection, and T1-weighted images were obtained approximately 20 minutes after the injection. None of the patients experienced allergic reactions or other side effects. Physical examination findings and laboratory values were unchanged after the Gd-DTPA-enhanced examination. In six patients, contrast-enhanced images depicted tumor not suspected on nonenhanced images. In four other patients, enhanced images provided better definition of the tumor core. The images of one patient with a brain stem tumor showed no evidence of enhancement. Pre- and postcontrast images of three previously treated patients showed no evidence of tumor. Gd-DTPA appears to be a safe and effective contrast agent for MR imaging and provides a more accurate method of imaging in the follow-up of brain tumors in pediatric patients.     

Comparison of gadobenate dimeglumine and gadopentetate dimeglumine: a study of MR imaging and inductively coupled plasma atomic emission spectroscopy in rat brain tumors

BACKGROUND AND PURPOSE: After the advent of extracellular contrast media, hepatobiliary-specific gadolinium chelates were developed to improve the diagnostic value of MR imaging of the liver. Gadobenate dimeglumine (Gd-BOPTA) is a new paramagnetic contrast agent with partial biliary excretion that produces prolonged enhancement of liver parenchyma on T1-weighted images. However, whether Gd-BOPTA is useful as a contrast agent in central nervous system disease, particularly in brain tumors, is unclear. METHODS: The behavior of Gd-BOPTA as a brain tumor-selective contrast agent was compared with that of gadopentetate dimeglumine (Gd-DTPA), an MR contrast agent used in central nervous system disease, in a common dose of 0.1 mmol/kg. An MR imaging study of these two contrast agents was performed, and tissue concentrations were measured with inductively coupled plasma atomic emission spectroscopy (ICP-AES). RESULTS: Gd-BOPTA showed better MR imaging enhancement in brain tumors than did Gd-DTPA at every time course until 2 hours after administration and no enhancement in peritumoral tissue and normal brain. Corresponding results with ICP-AES showed significantly greater uptake of Gd-BOPTA in tumor samples than that in peritumoral tissue and normal brain 5 minutes after administration. Gadolinium was retained for a longer time in brain tumors when Gd-BOPTA rather than Gd-DTPA was administered. CONCLUSION: Gd-BOPTA is a useful contrast agent for MR imaging in brain tumors and possibly an effective absorption agent for neutron capture therapy.     

Gd-DTPA enhanced MR imaging in intracranial tuberculosis

Summary Twenty-six patients with intracranial tuberculosis (Tb) (10 with acute meningitis, 5 with chronic meningitis, 5 with meningitic sequelae and 6 with localized tuberculoma(s) were examined with MR before and after Gd-DTPA enhancement (0.1 mmol/kg), using 2.0T superconducting unit, and the images were retrospectively analyzed and compared with CT scans. Without Gd-DTPA enhancement, the MR images were generally insensitive to detection of active meningeal inflammation and granulomas. The signal intensity of granulomas was usually isointense to gray matter on both T1- and T2-weighted images, whether they were associated with diffuse meningitis or presented as localized tuberculoma(s). A few granulomas showed focal hypointensity on T2-weighted images. Calcifications seen on CT of the meningitic sequelae group usually appeared markedly hypointense on all spin-echo sequences. On Gd-DTPA enhanced T1-weighted images, abnormal meningeal enhancement indicating active inflammation was conspicuous, and the granulomas often appeared as conglomerated ring-enhancing nodules, which seems to be characteristic of granulomas. Thin rim enhancement around the suprasellar calcifications were observed in two out of 5 patients with meningitic sequelae. Compared with CT, MR detected a few more ischemic infarcts, hemorrhagic infarcts, meningeal enhancement and granulomas in the acute meningitis group, but missed small calcifications in the basal cisterns well shown on CT in the sequelae group. Otherwise, MR generally matched CT scans. MR imaging appears to be superior to CT in evaluation of active intracranial Tb only if Gd-DTPA is used, while CT is better than MR in evaluating meningitic sequelae with calcification.     

CT and MR of neurofibromatosis of the bladder.

Neurofibromatosis of the genitourinary system is rare. We present the CT and MR findings of neurofibromas of the bladder in three patients with von Recklinghausen disease (neurofibromatosis, Type 1). In one case, genitourinary involvement was the primary presentation of the disease. Both CT and MR imaging revealed diffuse and nodular bladder wall involvement, along with pelvic sidewall and adjacent soft tissue abnormalities. The CT attenuation coefficients measured near soft tissue density. On T1-weighted spin echo MR images the tumors revealed signal intensity slightly greater than that of skeletal muscle. Neurofibromas showed markedly increased signal intensity on T2-weighted images relative to the surrounding soft tissues, with marked enhancement in two cases imaged following Gd-DTPA administration. Obstructive hydronephrosis was present in all cases, presumably due to neurofibromas involving the trigonal region. Pelvic sidewall tumors were visualized as rounded, nodular masses extending into the obturator foramina. In the evaluation of patients with von Recklinghausen disease, MR imaging, compared with CT, more clearly defined tumor extent within the bladder, pelvic sidewalls, and surrounding soft tissues.     

Gd-DTPA as a contrast agent in CT

An evaluation was done of the effect of gadolinium diethylenetriaminepentaacetic acid (DTPA) on computed tomographic (CT) studies performed after magnetic resonance (MR) imaging. CT scans of two solutions of Gd-DTPA demonstrated substantial attenuation. In two patients who underwent CT after Gd-DTPA-enhanced MR imaging, the high attenuation of concentrated Gd-DTPA was seen in the urinary bladder and renal collecting system. However, in the concentration presently used in MR imaging, Gd-DTPA results in only minor enhancement of renal cortex.     

Magnetic resonance imaging of small nasopharyngeal tumors

Magnetic resonance (MR) images of 9 patients with a small nasopharyngeal tumor were examined, and among them three cases were evaluated with Gd-DTPA enhancement technique. All cases showed no asymmetry of parapharyngeal space, but they presented neck lymph nodes swelling. These cases were proved malignant by surgical procedures and the blind biopsy. MR findings of levator and tensor veli palatini muscles and retropharyngeal lymph nodes were retrospectively evaluated in correlation with endoscopic examination and biopsy. In six cases among 9 patients, MR images demonstrated tumors on the lateral wall of nasopharynx. Infiltration of levator veli palatini muscle was an especially important earlier sign of nasopharyngeal tumor invasion because the levator veli palatini muscle belongs to the intrapharyngeal muscle group. Endoscopic examination could not reveal any abnormal lesion in three cases among these 6 cases. No definite signal intensity difference between tumor and pharyngeal mucosa was shown on both T1 and T2 weighted images. But the normal pharyngeal mucosa had demonstrated higher intensity than tumor with Gd-DTPA administration. So the enhanced nasopharyngeal MR imaging made the clear intensity difference between tumor and muscle tissue. It was the conclusion that MR imaging was superior to X-CT in detecting small nasopharyngeal tumor.     

Gd-DTPA-enhanced MR imaging of the brain in patients with meningitis: comparison with CT

Plain and Gd-DTPA-enhanced MR images of the brain were obtained in 18 consecutive patients with meningitis (eight with tuberculous, five with bacterial, three with viral, and two with fungal infections); the MR images were compared with CT scans. MR images were obtained on a 2.0-T superconducting unit with both T1- and T2-weighted pulse sequences before injection and with a T1-weighted sequence after injection of Gd-DTPA (0.1 mmol/kg) in all patients. In tuberculous meningitis, MR imaging depicted ischemia/infarct, hemorrhagic infarct of basal ganglia, meningeal enhancement at either basal cistern or convexity surface of brain, and associated small granulomas in a few more patients than CT did. In bacterial meningitis, primary foci of extracranial inflammation (i.e., mastoid, paranasal sinuses) and adjacent intracranial lesions including localized dural inflammation, subdural fluid collection, and/or brain parenchymal lesions were demonstrated much better on MR than on CT. Otherwise, MR images generally matched the CT scan. Although the plain MR images, both T1- and T2-weighted, were the most sensitive in delineating ischemia/infarct, hemorrhage, and edema, they were not as specific as Gd-DTPA-enhanced T1-weighted images and postcontrast CT scans in defining the active inflammatory process of the meninges and focal lesions precisely. We conclude that if Gd-DTPA is used, MR imaging appears to be superior to CT in the evaluation of patients with suspected meningitis. Precontrast MR is needed to delineate ischemia/infarct, edema, and subacute hemorrhage.     

Gd-DTPA-enhanced MR imaging of the brain in patients with meningitis: comparison with CT

Plain and Gd-DTPA-enhanced MR images of the brain were obtained in 18 consecutive patients with meningitis (eight with tuberculous, five with bacterial, three with viral, and two with fungal infections); the MR images were compared with CT scans. MR images were obtained on a 2.0-T superconducting unit with both T1- and T2-weighted pulse sequences before injection and with a T1-weighted sequence after injection of Gd-DTPA (0.1 mmol/kg) in all patients. In tuberculous meningitis, MR imaging depicted ischemia/infarct, hemorrhagic infarct of basal ganglia, meningeal enhancement at either basal cistern or convexity surface of brain, and associated small granulomas in a few more patients than CT did. In bacterial meningitis, primary foci of extracranial inflammation (i.e., mastoid, paranasal sinuses) and adjacent intracranial lesions including localized dural inflammation, subdural fluid collection, and/or brain parenchymal lesions were demonstrated much better on MR than on CT. Otherwise, MR images generally matched the CT scan. Although the plain MR images, both T1- and T2-weighted, were the most sensitive in delineating ischemia/infarct, hemorrhage, and edema, they were not as specific as Gd-DTPA-enhanced T1-weighted images and postcontrast CT scans in defining the active inflammatory process of the meninges and focal lesions precisely. We conclude that if Gd-DTPA is used, MR imaging appears to be superior to CT in the evaluation of patients with suspected meningitis. Precontrast MR is needed to delineate ischemia/infarct, edema, and subacute hemorrhage.     

Gadolinium-DTPA enhanced MR imaging in tuberous sclerosis

Summary Ten patients with clinical tuberous sclerosis were examined with CT and MR imaging, before and after IV contrast in order to determine the role of Gd-DTPA. Gd-DTPA enhancement occured in eleven subependymal nodules which did not enhance on CT after IV contrast. As illustrated by previous CT and pathologic observations and related to the histologic similarity of the subependymal nodules and giant-cell astrocytomas, these hyperintense nodules could represent active lesions with the potential to evolve. Four giant-cell astrocytomas were detected both with CT and Gd-DTPA-enhanced MRI; tumor conspicuity and size assessment were improved by postcontrast MRI in two cases. No cortical tuber or heterotopic cluster enhanced; T2-weighted sequences therefore remain necessary for their detection. If pre and post-Gd-DTPA T1-and T2-weighted imaging is negative, CT is clearly the most sensitive modality in the detection of the small calcified subependymal nodules.     

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.     

Sodium-23 imaging of supratentorial lesions at 4.0 T.

In 27 patients with low and high grade gliomas (n = 17), meningiomas (n = 4), and other supratentorial tumors and lesions (n = 6), the results of sodium-23 MR imaging with high spatial resolution were compared to CT and proton MRI. The Na MR studies were performed with a 4.0-T whole-body MR system and an isotropic 3D-Flash sequence (TR 70 ms, TE 11 ms), which depicts the long T2 component of sodium. All patients tolerated the sodium study at 4.0 T well. The sodium images revealed almost all lesions, but the resolution was inferior to that of the reference methods. Two small meningiomas did not show up at all in the sodium study. Furthermore in one case small hemorrhages and calcifications within one of the tumors could not be found. Sodium imaging of the long T2 component did not provide any additional information regarding the histology, grading, size, and differentiation of the tumor from the surrounding edema which had not already been provided by CT or H MRI.     

MR imaging characterization of microvessels in experimental breast tumors by using a particulate contrast agent with histopathologic correlation

PURPOSE: To define the diagnostic potential of magnetic resonance (MR) imaging enhanced with ultrasmall superparamagnetic iron oxide (USPIO) particles for the quantitative characterization of tumor microvasculature. MATERIALS AND METHODS: NC100150 injection, a USPIO in clinical trials, and albumin-(Gd-DTPA)(30) were compared at MR imaging on sequential days in the same 19 rats with mammary tumors. Kinetic analysis of dynamic T1-weighted three-dimensional spoiled gradient-recalled imaging data with a two-compartment bidirectional model yielded MR imaging estimates of microvascular permeability (K(PS)) and fractional plasma volume (fPV) for each contrast medium. RESULTS: Strongly positive and significant correlations were observed between MR imaging-derived K(PS )estimates and histologic tumor grade with either the soluble albumin-(Gd-DTPA)(30) (r = 0.88; P <.001) or larger particulate USPIO (r = 0.82; P <.001). A significant correlation (P <.05) was observed with each contrast medium between K(PS) and the histologic microvascular density (MVD), an angiogenesis indicator. Despite the considerable difference in molecule and particle sizes, no significant difference was observed in the MR imaging-derived mean permeability values generated with the two contrast media. CONCLUSION: USPIO, a macromolecular particulate MR imaging contrast agent, can be applied successfully to characterize tumor microvessels in animals. USPIO-derived K(PS) correlated strongly with histopathologic tumor grade, MVD, and K(PS) values derived by using albumin-(Gd-DTPA)(30) in the same tumors.     

瘤周水肿的CT灌注成像与MR灌注成像初步比较研究

目的比较CT灌注成像和MR灌注成像瘤周水肿区相对脑血容量（rCBV）对鉴别高级别神经上皮肿瘤与转移瘤的价值。资料与方法选取同时行CT灌注成像和MR灌注成像检查的14例高级别神经上皮肿瘤（WHOⅢ、Ⅳ级）和8例转移瘤患者,比较瘤周水肿rCBV的鉴别诊断效果。结果CT灌注成像和MR灌注成像均显示高级别神经上皮肿瘤瘤周水肿区rCBV高于转移瘤者,差异有统计学意义（P〈0.05）。二者的受试者工作特性曲线（ROC）下面积分别为0.911和0.929。结论CT灌注成像和MR灌注成像瘤周水肿区rCBV对高级别神经上皮肿瘤与转移瘤的鉴别诊断均具有很高的价值,以MR灌注成像更佳。     

Gadolinium-DTPA in magnetic resonance tomography. Clinical use--indications

Magnetic resonance tomography was performed on 158 patients with different indications before and after the administration of contrast medium. The MR examination included various plain T1 and T2 weighted spin echo sequences as well as T1 weighted examinations after intravenous application of Gadolinium-DTPA ("Magnevist", Schering AG) in a dosage of 0.1 mmol/kg body weight. The following conclusions were drawn: The sensitivity of MR in detecting brain tumors, acoustic neuromas and pituitary adenomas was improved considerably after the administration of "Magnevist". To diagnose the type of tumor, the criteria which apply to Gd-DTPA are similar to those used for iodine-containing contrast medium in CT. In about 2/3rds of the cases, delineation of pathological tissues from surrounding edema and normal structures was better than in plain films. Hence, accurate, pretherapeutic staging of bronchial carcinomas and an exact definition of the expansion of the malignancies in the muscle-skeleton system were possible. In respect of tumors in the region of the base of the skull, we could omit T2-weighted sequences without noticeable loss of diagnostically relevant information; the examination time could thus be shortened by about 12 minutes.     

椎管内微小占位性病变的MRI诊断

目的:研究椎管内微小占位性病变的MRI特征及其对病变定性、定位诊断的意义。材料与方法:24例椎管内微小占位性病变患者(男12例,女12例,年龄23～67岁,平均29.1岁)均经PHILIPS 1.0NT型MR仪行常规T_1WI、T_2WI磁共振成像,其中6例又经Gd-DTPA增强扫描。全部病例的椎管内占位病变均经病理证实,并对其MRI表现进行了回顾性分析。结果:24例的病变经病理证实,18例为胚胎源性肿瘤(10例表皮样囊肿,4例皮样囊肿,4例畸胎瘤),4例为神经源性肿瘤(3例神经鞘瘤,1例神经纤维瘤),以及脊膜瘤与脂肪瘤各1例。各种占位性病变的MRI表现随其不同的组织学来源而有很大差别。表皮样囊肿多为均质长T_1长T_2信号。皮样囊肿以短T_1,长T_2信号为主。畸胎瘤呈混杂信号。神经鞘瘤为T_1WI低信号、T_2WI高信号,Gd-DTPA增强扫描后,囊壁均匀强化,偶见强化附壁结节。神经纤维瘤呈均质长T_1、长T_2信号,Gd-DTPA增强扫描后,病灶呈异常对比增强。脊膜瘤呈长T_1、稍长T_2信号,Gd-DTPA增强扫描后,病灶呈异常对比强化,并见局部硬脊膜增厚强化而形成的硬膜尾征。结论:各种病变的MRI表现随其组织学来源不同而有明显差异,它们在椎管内微小占位性病变的定性、定位诊断中起着重要作用,其诊断准确性优于X线椎管造影与CT。     

MR imaging of intraocular lesions--a comparison with CT]

Thirty-two intraocular lesions were studied with magnetic resonance (MR) imaging and computed tomography (CT). These lesions included retinoblastoma (n = 11), uveal melanoma (n = 6), metastatic choroidal tumor (n = 3), choroidal hemangioma (n = 2), retinochoroiditis (n = 6) and Coats' disease (n = 4). MR imaging was superior to CT in the depiction of intraocular masses and retinal detachment. Gd-DTPA enhanced MR imaging was more useful than contrast enhanced CT in evaluating the contrast enhancement of intraocular tumors. Differential diagnosis of intraocular tumors was difficult with both MR imaging and CT. Intratumoral calcification was noticed on CT in nine cases of retinoblastoma. It was concluded that MR imaging, including contrast enhancement study, is more useful than CT in the evaluation of intraocular lesions, except for calcification, and contrast enhanced CT may be unnecessary in the diagnosis of intraocular lesions.