Single-dose contrast agent for intraoperative MR imaging of intrinsic brain tumors by using ferumoxtran-10

BACKGROUND AND PURPOSE: Intraoperative MR imaging (IMRI) has advantages over conventional framed and frameless techniques. IMRI, however, also has some drawbacks, especially related to interpretation of gadolinium-enhanced intraoperative imaging resulting from surgically induced blood brain barrier injury, vascular changes, and hemorrhage. Ultra-small superparamagnetic iron particles like ferumoxtran-10 have a long plasma half-life and are trapped by reactive cells within the tumor. These trapped particles provide a method to demonstrate enhancing lesions without the artifact of repeat gadolinium administration in the face of blood brain barrier and vascular injury. METHODS: We present a review of the literature and the cases of two patients who underwent surgery in which IMRI with ferumoxtran-10 was used. RESULTS: Ultra-small superparamagnetic iron particles represent a method to demonstrate enhancing intrinsic brain tumors without the drawbacks of intraoperative gadolinium enhancement. These lesions appear even on low-field strength IMRI. Ferumoxtran-10, administered preoperatively, provides a stable imaging marker, even after surgical manipulation of the brain. CONCLUSION: Fermumoxtran-10 provides a way to lessen artifactual enhancement during IMRI related to the administration of gadolinium.     

Splenic imaging with ultrasmall superparamagnetic iron oxide ferumoxtran-10 (AMI-7227): preliminary observations

PURPOSE: Ferumoxtran-10 (ultrasmall superparamagnetic iron oxide; Combidex, AMI-7227) is a long-circulating MR contrast agent with reticuloendothelial uptake known to enhance tissue T1 and T2 relaxation rates. The purpose of this study was to assess the effect of ferumoxtran-10-enhanced MRI in evaluating focal splenic lesions. METHOD: Eighteen patients underwent MR evaluation of the spleen. Two of these patients with exophytic normal splenic tissue (splenules) and 13 of these patients with 24 focal splenic lesions (7 cysts, 2 hemangiomas, 7 metastases, 1 infarct, 7 lymphoma) were assessed by T1-weighted gradient echo and T2-weighted fast SE MRI following intravenous administration of ferumoxtran-10 (1.1 mg of Fe/kg). Qualitative analysis involving improved lesion detection and/or characterization, additional information from postcontrast images affecting staging, and patient management was performed. Quantitative measurements of lesion-to-spleen contrast-to-noise ratio were also performed. RESULTS: Additional information was provided by ferumoxtran-10-enhanced images in 15 of 18 patients. In 8 of 15 (53%) patients, improved lesion detection (i.e., number of lesions) was obtained on contrast-enhanced images. Improved lesion visualization (i.e., conspicuity) was noted in 11 of 15 (73%) of patients. In 10 of 15 (67%) patients, postcontrast imaging provided additional information leading to lesion characterization. Staging of disease and patient management were affected in 5 of 15 (33%) and 6 of 15 (40%) patients, respectively. CONCLUSION: Ferumoxtran-10 is a promising contrast agent for the evaluation of focal splenic lesions.     

Ferumoxtran-10-enhanced MR imaging of the bone marrow before and after conditioning therapy in patients with non-Hodgkin lymphomas

To quantify permeability changes of the “blood–bone marrow barrier” (BMB) and to detect malignant bone marrow infiltrations before and after conditioning therapy for subsequent leukapheresis using ferumoxtran-10-enhanced magnetic resonance (MR) imaging. Twenty-two patients with malignant non-Hodgkin lymphomas (NHL), including 9 patients (group A) before and 13 patients (group B) after conditioning therapy, underwent MR of the spine before and after infusion of ferumoxtran-10 (0.045 mmol Fe/kg BW). Pulse sequences comprised dynamic T1-GE and pre- and post-contrast T1-SE and STIR sequences. Dynamic ΔSI-data were correlated with the quantity of mobilized CD34+ cells. In addition, the number of focal bone marrow lesions was compared before and after ferumoxtran-10 administration. Dynamic ΔSI-data were higher in group B than in group A, indicating an increased BMB permeability after conditioning therapy. However, ΔSI-data did not correlate with the quantity of mobilized CD34+ cells. Ferumoxtran-10-enhanced STIR images demonstrated a significant signal decline of the normal, non-neoplastic bone marrow and a significantly increased detection of focal neoplastic lesions compared to pre-contrast images (P<0.05). Ferumoxtran-10 depicted the bone marrow response to conditioning therapy by an increase in BMB-permeability, which, however, did not correlate with the number of mobilized CD34+ cells. Ferumoxtran-10 improved the detection of focal bone marrow lesions significantly (P<0.05).     

Gadolinium enhancement in acute disseminated encephalomyelitis

Acute disseminated encephalomyelitis (ADEM) is a widespread CNS inflammation that usually follows an infection or vaccination. We present a case of ADEM, which in addition to the typical MR findings, demonstrates gadolinium enhancement of several of the lesions. Since ADEM is usually a monophasic illness, it has been postulated that all lesions might enhance with paramagnetic contrast medium since they would all be expected to be active. Our case demonstrates enhancement of some of the lesions, without enhancement of others.     

Ultrasmall superparamagnetic iron-oxide-enhanced MR imaging of normal bone marrow in rodents: original research original research

RATIONALE AND OBJECTIVES: The objective is to compare three different ultrasmall superparamagnetic iron oxides (USPIOs) for magnetic resonance (MR) imaging of normal bone marrow in rodents. MATERIALS AND METHODS: Femoral bone marrow in 18 Sprague-Dawley rats was examined by using MR imaging before and up to 2 and 24 hours postinjection (PI) of 200 mumol of Fe/kg of SHU555C (n = 6), ferumoxtran-10 (n = 6), or ferumoxytol (n = 6), using T1-weighted (50 ms/1.7 ms/60 degrees = repetition time [TR]/echo time [TE]/flip angle) and T2*-weighted (100 ms/15 ms/38 degrees = TR/TE/flip angle) three-dimensional spoiled gradient recalled echo sequences. USPIO-induced bone marrow was evaluated qualitatively and quantified as signal-to-noise ratio (SNR) and change in signal intensity (DeltaSI) values. A mixed-effect model was fitted to the SNR and DeltaSI values, and differences among USPIOs were tested for significance by using F tests. RESULTS: At 2 hours PI, all three USPIOs showed marked positive signal enhancement on T1-weighted images and a corresponding marked signal loss on T2*-weighted images. At 24 hours PI, the T1 effect of all three USPIOs disappeared, whereas T2*-weighted images showed persistent signal loss on SHU555C and ferumoxytol-enhanced MR images, but not ferumoxtran-10-enhanced MR images. Corresponding SNR and DeltaSI values on T2*-weighted MR images at 24 hours PI were significantly different from baseline for SHU555C and ferumoxytol, but not ferumoxtran-10. CONCLUSION: All three USPIO contrast agents, ferumoxtran-10, ferumoxytol, and SHU555C, can be applied for MR imaging of bone marrow. Ferumoxtran-10 apparently reveals a different kinetic behavior in bone marrow than ferumoxytol and SHU555C.     

MR imaging of relapsing multiple sclerosis patients using ultra-small-particle iron oxide and compared with gadolinium

BACKGROUND AND PURPOSE: Inflammatory multiple sclerosis (MS) lesions are characterized by microglia activation and infiltration of T cells, B cells, and macrophages across the blood-brain barrier (BBB). In the experimental autoimmune encephalomyelitis (EAE) rat model of MS, previous MR imaging investigations with a new contrast agent ultra-small-particle iron oxide (USPIO) that accumulates in phagocytic cells revealed in vivo the presence of macrophage brain infiltration. The goal of this study was to characterize MS lesions with the use of this contrast agent. METHODS: A prospective MR imaging study of 10 patients with MS in acute relapses was achieved by using USPIO and gadolinium. RESULTS: Twenty-four hours after USPIO injection, 33 acute MS lesions in 9 patients showed USPIO uptake. Lesions were seen as high signal intensities on T1-weighted images and low signal intensities on T2-weighted images. Gadolinium enhancement was seen in 31 of these lesions in 7 patients. These 7 patients presented 24 gadolinium-enhanced lesions that did not enhance with USPIO. Two patients showed USPIO-enhanced lesions but no gadolinium-enhanced lesions. CONCLUSION: Taken together with earlier findings obtained in experimental models or in human stroke, the visualization of macrophage activity in vivo with USPIO characterize a distinct cellular and inflammatory event of the dynamic process of MS lesion formation. The macrophage activity information obtained with USPIO is distinct and complementary to the increased BBB permeability seen with gadolinium.     

MR of primary CNS lymphoma in immunologically normal patients.

PURPOSE: To describe the MR findings of primary CNS lymphoma. METHODS: MR scans of 20 patients with histologically proved primary CNS lymphoma were reviewed. We evaluated the size, multiplicity, signal intensities, and enhancement characteristics of the lesions. We divided the lesions into an enhancing area referred to as Zone 1 and abnormal signal surrounding this, referred to as Zone 2. RESULTS: Primary CNS lymphoma presented as solitary enhancing lesions in 40% of the patients and multiple lesions in 40%. Thirty-three separate lesions were visible: 58% abutted the ventricular system, 76% showed a homogenous enhancement pattern, and 79% showed marked enhancement. In 64% of the lesions, Zone 1 and Zone 2 showed different signal intensities on T1-weighted images. CONCLUSIONS: Primary CNS lymphoma usually presents as solitary or multiple dense homogenous enhancing lesions that abut an ependymal surface. These lesions can be divided into an enhancing area and an area of surrounding abnormal signal. These two areas often have different signal intensities on unenhanced T2-weighted images. These findings are sufficiently suggestive of the diagnosis of primary CNS lymphoma that a needle biopsy be performed based on these findings and appropriate therapy can then be instituted.     

MR imaging enhancement patterns as predictors of hemorrhagic transformation in acute ischemic stroke

BACKGROUND AND PURPOSE: Early parenchymal gadolinium enhancement on T1-weighted MR images is predictive of hemorrhagic transformation (HT) in rodent focal ischemia models, but its value in humans is unknown. We sought to investigate gadolinium enhancement in acute ischemic stroke patients to determine their association with subsequent HT. METHODS: We retrospectively examined 22 patients with ischemic stroke who underwent MR imaging within 4.9 hours (+/-1.4) of symptom onset. Patients receiving intravenous tissue plasminogen activator (tPA) (n = 6) were included. Twenty-one patients underwent repeat MR studies at 48 hours, 13 underwent additional MR imaging at 1 week, and one underwent follow-up head CT at 24 hours. Initial images were analyzed for enhancement patterns (vascular, meningeal, parenchymal). Follow-up T2- and T2*-weighted images were evaluated for hemorrhage. RESULTS: In all patients, initial MR images showed vascular enhancement in the vascular territory of the stroke lesion: 19 with vascular enhancement alone and three with vascular and parenchymal enhancement. All three patients with both enhancement patterns had HT: two large and symptomatic, and one asymptomatic (petechial hemorrhage). They received tPA before MR imaging. None of the patients without early parenchymal enhancement developed symptomatic hemorrhage. Six (32%) patients with vascular enhancement alone had petechial hemorrhage at follow-up imaging. In this limited sample, initial mean volumes on diffusion-weighted images, National Institute of Health Stroke Scale scores, and intervals from stroke onset to imaging did not differ between patients with vascular and parenchymal enhancement versus those with vascular enhancement alone. CONCLUSION: Early parenchymal enhancement of stroke lesions may be a good predictor of subsequent symptomatic HT may help identify patients at risk, especially after thrombolytic therapy.     

Magnetization transfer and diffusion tensor MR imaging of acute disseminated encephalomyelitis

BACKGROUND AND PURPOSE: Patients with acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS) have a similar pattern of abnormalities on conventional MR images. We used magnetization transfer and diffusion tensor MR imaging to quantify normal-appearing brain tissue and cervical cord disease in patients with ADEM and to compare findings with those in healthy volunteers and patients with MS. METHODS: Brain dual-echo, T1-weighted magnetization transfer, and diffusion tensor images were obtained in eight patients with ADEM, in 10 patients with MS, and in 10 healthy volunteers. Fast short-tau inversion recovery, T1-weighted, and magnetization transfer cervical cord images were also obtained. We identified lesions on the images and quantified their volumes. We performed histogram analysis of the magnetization transfer ratio (MTR) and average mean histogram analysis of the diffusivity (D) in normal-appearing brain tissue and MTR in the cervical cord. RESULTS: Histogram analysis of normal-appearing brain tissue in patients with MS showed significantly lower MTRs and peak positions and significantly higher D averages compared with those in patients with ADEM. Patients with MS had significantly lower MTRs and D peak heights and significantly higher average D compared with those in healthy volunteers. Between patients with ADEM and control subjects, normal-appearing brain tissue MTR and D histogram metrics did not differ significantly. Cervical cord MTRs did not differ between control subjects and patients with ADEM, whereas the average MTR and histogram peak position was significantly lower in patients with MS than in the other groups. CONCLUSION: Outside the acute phase of disease and as opposed to what happens in MS, the normal-appearing brain tissue and cervical cord in patients with ADEM are spared in the pathologic process.     

Ferumoxtran-10-enhanced MR lymphangiography: does contrast-enhanced imaging alone suffice for accurate lymph node characterization?

OBJECTIVE: Ferumoxtran-10 is a lymphotropic MR contrast agent that is currently under investigation. It has been shown to be effective in staging lymph nodes of patients with various primary malignancies. The current technique with ferumoxtran-10 involves imaging before and 24 hr after contrast administration. The purpose of this study was to evaluate the accuracy of ferumoxtran-10-enhanced images alone in characterizing lymph nodes for oncologic staging 24 hr after contrast enhancement. MATERIALS AND METHODS: Seventy-seven patients (58 men, 19 women) with proven primary cancer (bladder [n = 20], breast [n = 10], endometrial [n = 1], renal [n = 3], penile [n = 4], prostate [n = 31], rectal [n = 1], testicular [n = 5], and ureteral [n = 2]) who were scheduled for surgical lymph node dissection were enrolled in the study. In these patients, 169 lymph nodes (mean size, 11.2 mm) were evaluated on T2*-weighted gradient-refocused echo MRI at l.5 T both before and 24-36 hr after the IV administration of ferumoxtran-10 (2.6 mg Fe/kg). Two blinded reviewers with differing levels of interpreting experience separately performed qualitative image evaluation. A 6-point scale was used to characterize lymph nodes on contrast-enhanced images alone and on combined unenhanced and contrast-enhanced images. Receiver operating characteristic (ROC) analysis was performed separately for both reviewers. RESULTS: Of the 169 lymph nodes evaluated, 55 were benign and 114 malignant by histopathologic analysis. The results of the ROC analysis comparing contrast-enhanced images ([A(z) = area under ROC curve] reviewer 1, A(z) = 0.92; reviewer 2, A(z) = 0.94) alone with combined unenhanced and contrast-enhanced images (reviewer 1, A(z) = 0.94; reviewer 2, A(z) = 0.93) showed a statistically significant difference (p = 0.01) for reviewer 1 but no difference for reviewer 2 (p = 0.88). Reviewer 2 was more experienced in interpreting ferumoxtran-10-enhanced images than reviewer 1. CONCLUSION: On ferumoxtran-10-enhanced MR lymphangiography, contrast-enhanced images alone may suffice for lymph node characterization. However, a certain level of interpretation experience may be required before contrast-enhanced images can be used alone.     

Preclinical safety and pharmacokinetic profile of ferumoxtran-10, an ultrasmall superparamagnetic iron oxide magnetic resonance contrast agent

OBJECTIVES: This report presents an overview of preclinical data available on ferumoxtran-10, an ultrasmall superparamagnetic iron oxide nanoparticular contrast agent proposed for lymph node magnetic resonance imaging. MATERIALS AND METHODS: Pharmacokinetic, safety pharmacology, single- and repeat-dose toxicity, reproduction toxicity, and genotoxicity studies were performed with ferumoxtran-10 given intravenously (bolus injection) in mice, rats, rabbits, dogs, and monkeys. RESULTS: Ferumoxtran-10 was taken up by macrophages, mostly in liver, spleen, and lymph nodes, within 24 hours after bolus injection and underwent progressive metabolism. Toxicity was observed only at very high exposure levels and mainly was linked to a massive iron load after repeated injections. Ferumoxtran-10 was not mutagenic but was teratogenic in rats and rabbits. DISCUSSION: The preclinical pharmacokinetic and safety profile of ferumoxtran-10 appears to be satisfactory in view of its proposed use as a single-dose diagnostic agent in human for MR imaging of lymph nodes.     

Three subsequent single doses of gadolinium chelate for brain MR imaging in multiple sclerosis

BACKGROUND AND PURPOSE: A triple-dose (TD) of gadolinium chelate is highly sensitive approach for detecting lesion activity in multiple sclerosis (MS). However, individual TD injections do not provide data on the severity of the pathologic process in a population of lesions, and its clinical use is limited by the cost-benefit considerations. Our aim was to determine whether the use of three subsequent single doses (SD) of a gadolinium chelate in brain MR imaging is useful in detecting MS lesions with different patterns of enhancement. METHODS: In 10 patients, T1-weighted spin-echo images were acquired before and after three intravenous administrations of 0.1 mmol/kg of gadodiamide. RESULTS: In all patients, SD images showed six enhancing lesions; double-dose (DD) images, 13; and TD images, 22. Differences between SD and TD and between DD and TD were significant (P <.018). Six lesions (27%) enhanced with all the three doses; seven (32%), with both DD and TD; and nine (41%), with only TD. Proportions of patients with at least one enhancing lesion were, for SD, four of 10; DD, seven of 10; and TD, nine of 10. In defining active disease in these nine patients, we needed only 19 SDs versus the 30 SDs that would have been needed if individual TD injections were used. CONCLUSION: With three subsequent SD injections, the number of enhancing lesions progressively increases. This approach allows the distinction of three levels of enhancement, and it reduces the amount of contrast agent needed to distinguish patients with active MS from those with nonactive MS.     

双侧肾上腺非霍杰金淋巴瘤CT、MRI动态增强诊断价值

目的:探讨双侧肾上腺淋巴瘤CT、MRI动态增强影像特征。方法:回顾性分析经手术病理证实的双侧肾上腺非霍杰金淋巴瘤6例。其中继发性非霍杰金淋巴瘤5例,原发性非霍杰金淋巴瘤1例。男4人,女2。年龄35～75岁,平均63岁。全部病例均行CT平扫和动态增强检查。1例行MR平扫和增强检查。所有病例影像资料均经2名高年医师在不知道病理结果的情况下分析阅片,分别确定病变大小、形态、边缘、密度以及强化程度,以及是否伴腹膜后淋巴结肿大。结果:12个病灶中,6个病灶呈椭圆形,肿块形4个,2个病灶呈肾上腺增生改变。肿瘤直径3.9～8.0cm。10个病灶CT平扫密度均匀,2个病灶密度不均匀,其中一个病灶内可见坏死。平扫CT值为24.1～35.2HU,平均25.5HU;CT动态增强动脉期病灶轻度强化,10个病灶均匀强化,2个病灶不均匀强化,其内可见条状、网格状强化。动脉期CT值28.3～44.7HU,平均31.6HU。门静脉期继续强化,门静脉期CT值36.4～64.6HU,平均48.7HU。MR扫描T1WI信号为均匀稍低信号,T2WI扫描信号为稍高信号,增强扫描可见动脉期轻度强化,静脉期持续强化。3例伴腹膜后淋巴结肿大。2名医师诊断正确4例,2例误诊。结论:双侧肾上腺非霍杰金淋巴瘤密度相对均匀,坏死少见或范围较小,CT、MR动态增强呈轻～中等程度进行性延迟强化,强化较均匀。肾上腺淋巴瘤具有一定的影像学特点,术前CT、MR动态增强扫描有利于确诊。     

The variable MR appearance of primary lymphoma of the central nervous system: comparison with histopathologic features.

PURPOSETo describe the MR features of primary central nervous system (CNS) lymphoma and to determine whether there is a correlation with histopathologic findings.METHODSThe MR images, pathologic specimens, and clinical records of 23 patients with primary CNS lymphoma were reviewed. The imaging and pathologic characteristics were tabulated and compared by using the standard tests for association in a two-dimensional contingency table.RESULTSA total of 61 lesions were present in 23 patients; 12 patients (52%) had multiple lesions. All lesions were isointense or hypointense on T1-weighted images, and 53% were isointense or hypointense on T2-weighted images. Twenty patients received intravenous contrast material, and 43 (91%) of 47 lesions enhanced. The three patients who had nonenhancing lesions received steroids before the initial MR studies. Enhancement patterns differed between the immunocompetent and the immunocompromised hosts, with the latter group harboring a higher percentage of rim-enhancing lesions. Twenty-seven (44%) of the lesions were centered in a cerebral hemisphere and 14 (23%) were centered in the central gray matter. There was a statistically significant correlation between a higher degree of necrosis histologically and hyperintensity on T2-weighted MR images. The degree of necrosis also showed a positive correlation with rim enhancement.CONCLUSIONSPrimary CNS lymphoma has a variable MR appearance that correlates with the severity of intratumoral necrosis. These imaging characteristics, as well as lesion location, mean lesion size, and proclivity to harbor necrosis, are altered in the immunocompromised host.     

Multiple sclerosis: serial study of gadolinium-enhanced MR imaging

Thirteen patients with definite multiple sclerosis (MS), studied 16-24 months previously with magnetic resonance (MR) imaging with and without enhancement by intravenously administered gadolinium diethylenetriaminepentaacetic acid (DTPA) dimeglumine, were reexamined with a similar protocol. Assessment of enhancement and clinical activity in both studies revealed that enhancement was observed in 13 of 14 cases in which clinical activity had changed within 4 weeks of the study and thus appeared more sensitive than clinical examination in determining active disease. The 3-minute postinjection, short repetition time image (TR) was the most efficient for depicting enhancement. Enhancing lesions (active plaques) arose from previously hyper- or isointense regions on long TR images. Previously active lesions reverted to areas of iso- or hyperintensity on long TR images. Serial comparison of long TR images in this population reveals a decrease in high-intensity lesions on long TR images in some cases and an increase in others. The findings of high-intensity regions on long TR images and previously enhancing lesions both becoming isointense suggests that transient inflammatory changes with concomitant edema without demyelination and/or with significant remyelination may occur in some MS lesions. MS lesions are dynamic; both active and inactive lesions may show dramatic change on longitudinal MR imaging studies.     

Urinary bladder cancer: preoperative nodal staging with ferumoxtran-10-enhanced MR imaging

PURPOSE: To prospectively evaluate ferumoxtran-10-enhanced magnetic resonance (MR) imaging for nodal staging in patients with urinary bladder cancer. MATERIALS AND METHODS: Fifty-eight patients with proved bladder cancer were enrolled. Results of MR imaging performed before and after injection of ferumoxtran-10 were compared with histopathologic results in surgically removed lymph nodes. High-spatial-resolution three-dimensional T1-weighted magnetization-prepared rapid acquisition gradient-echo (voxel size, 1.4 x 1.4 x 1.4 mm) and T2*-weighted gradient-echo (voxel size, 0.8 x 0.8 x 3.0 mm) sequences were performed before and 24 hours after injection of ferumoxtran-10 (2.6 mg iron per kilogram of body weight). On precontrast images, lymph nodes were defined as malignant by using size and shape criteria (round node, >8 mm; oval, >10 mm axial diameter). On postcontrast images, nodes were considered benign if there was homogeneous decrease in signal intensity and malignant if decrease was absent or heterogeneous. Qualitative evaluation was performed on a node-to-node basis. Sensitivity, specificity, predictive values, and accuracy were evaluated with logistic regression analysis. RESULTS: In 58 patients, 172 nodes imaged with use of ferumoxtran-10 were matched and correlated with results of node dissection. Of these, 122 were benign and 50 were malignant. With nodal size and shape criteria, accuracy, sensitivity, specificity, and positive and negative predictive values on precontrast images were 92%, 76%, 99%, 97%, and 91%, respectively; corresponding values on postcontrast images were 95%, 96%, 95%, 89%, and 98%. In the depiction of pelvic metastases, sensitivity and negative predictive value improved significantly at postcontrast compared with those at precontrast imaging, from 76% to 96% (P < .001) and from 91% to 98% (P < .01), respectively. At postcontrast imaging, metastases (4-9 mm) were prospectively found in 10 of 12 normal-sized nodes (<10 mm); these metastases were not detected on precontrast images. Postcontrast images also showed lymph nodes that were missed at pelvic node dissection in two patients. CONCLUSION: Ferumoxtran-10-enhanced MR imaging significantly improves nodal staging in patients with bladder cancer by depicting metastases even in normal-sized lymph nodes.     

Appearance of primary lymphoid malignancies on lymphotropic nanoparticle-enhanced magnetic resonance imaging using ferumoxtran-10

Patients with pathologically confirmed lymphoma/leukemia were retrospectively identified from a large single-institution phase III clinical trial with ferumoxtran-10. Five (2.3%) of 220 patients had lymphoid malignancies involving lymph nodes. A subset of patients (n=27) with biopsy-proven nodal metastases from genitourinary or breast cancer was selected as control group. Ferumoxtran-10 enhancement patterns and signal-to-noise ratios of lymph nodes involved by metastases and lymphoid malignancy were assessed. Like nodal metastases, nodes involved by lymphoid malignancies demonstrate persistent high T2*-signal intensity on lymphotropic nanoparticle-enhanced magnetic resonance imaging.     

MR imaging of mediastinal lymph nodes: evaluation using a superparamagnetic contrast agent

The purpose of this study was to determine whether intravenous injection of a magnetic resonance (MR) contrast agent, ultrasmall superparamagnetic iron oxide (ferumoxtran-10), can be useful in characterizing lymph nodes in patients with lung cancer. Twelve patients with known or suspected lung cancer were studied. Pre- and postcontrast injection of ferumoxtran-10 MR scans of the chest were obtained. Analysis of the signal intensities and bronchoscopic fine needle aspiration of a single node were performed in each patient. Six of 12 patients had a final diagnosis of lung cancer. T1-weighted images were best for localizing mediastinal lymph nodes. Signal intensity changes before and after contrast were best visualized on T2-weighted and gradient-echo images. All four patients with lung cancer who had nodes positive for malignancy at biopsy had no change in signal intensity of the nodes on T2 images. The signal intensity decreased in the remaining two patients, and the nodes were benign. Of the eight patients with benign disease, five had no change in signal intensity of the nodes. Therefore the sensitivity for tumor involvement of the nodes is 100%, but the specificity is only 37.5%. Ferumoxtran-10 is a contrast agent that can alter the signal intensity of lymph nodes. Lack of signal change may be due to malignant or inflammatory change. Studies in a larger population of lung cancer patients may help to characterize the utility of this agent further. J. Magn. Reson. Imaging 2000;12:899-904.     

Diagnostic role of gadolinium-DTPA in pediatric neuroradiology

Summary We retrospectively reviewed the findings in 655 consecutive young patients who underwent contrastenhanced MR examinations (1.5T) of the head or spine. Their ages ranged from 4 months to 20 years (mean 10 years). There was a 1.7% incidence of minor adverse reactions to gadolinium (Gd)-DTPA, none of which required treatment; no serious adverse reactions were encountered. Based on the radiologic diagnosis the patients were divided into three groups: (1) normal, (2) CNS neoplasm, (3) abnormal but not neoplasm. There were 178 patients thought to have CNS neoplasms and of these 156 (88%) enhanced. Of 124 histologically confirmed neoplasms 115 (93%) showed enhancement after Gd-DTPA. Eight children had histologically confirmed spinal neoplasms; 5 of 6 neurofibromas and 2 ependymomas enhanced. In the 216 patients with abnormalities thought not to be neoplastic, the enhancement rate was 11%; most of the enhancing lesions were vascular malformations. There were very few examples of inflammatory disease, acute trauma or stroke among our patients.     

Non-Hodgkin lymphomas of the ovaries: MR findings

PURPOSE: The goal of this work was to describe MR findings (morphology, structure, signal intensity) of ovarian non-Hodgkin lymphoma (NHL). METHOD: We reviewed the MR images of five female patients aged 13-70 years (mean 46 years) with histologically proven NHL of the ovaries. We evaluated morphological and signal intensity findings of the lesions. MR features were correlated with pathologic parameters. RESULTS: All the patients were affected by B-cell NHL; one patient showed a primary involvement of the ovaries; in one patient, ovarian disease was diagnosed 30 months after surgical resection of a primary uterine lymphoma; the remaining three had a systemic lymphoma. In three cases, the ovarian involvement was bilateral. The mean size of the lesions was 7.9 cm. All the lesions showed homogeneous low signal intensity on T1-weighted images and intermediate to high intensity on T2-weighted images. The postgadolinium images showed mild to moderate heterogeneous enhancement. The peripheral enhancement was better demonstrated in fat-suppressed images. CONCLUSION: The diagnosis of primary ovarian lymphoma should be considered in the presence of large bilateral solid ovarian masses with homogeneous appearance (low signal on T1 and mildly high on T2) without infiltrative pattern of growth or regressive changes (necrosis, hemorrhage, calcifications) and with little contrast enhancement.