Prenatal diagnosis of anasarca in an end-second trimester fetus presenting with sacrococcygeal teratoma by magnetic resonance imaging

Fetal hydrops is a known complication of sacrococcygeal teratoma (SCT) due to arteriovenous shunts within the tumor, which is clinically important and influence patients' prognosis. We present unique MRI morphological findings of a marked fetal anasarca in a case of an end-second trimester fetus presenting with SCT.     

Effects of water exchange on MRI-based determination of relative blood volume using an inversion-prepared gradient echo sequence and a blood pool contrast medium

A prostate tumor model in rats was used to compare histometric parameters of prostate cancer physiology with those obtained by magnetic resonance imaging (MRI). The study was focused on vascular physiology as reflected by relative blood volume v(b). Histometry and MRI showed a significant increase in mean v(b) in tumor compared to normal prostate tissue (histometry: normal tissue v(b)=0.69+/-0.19%, tumor tissue v(b)=1.10+/-0.31%, P<.001; MRI: normal tissue v(b)=0.67+/-0.23%, tumor tissue v(b)=1.77+/-0.67%, P<.001). The experimental work showed that MRI yielded a 60.9+/-0.76% higher v(b) than histometry in tumors, while no significant difference in v(b) was found between both methods in normal prostate tissue. Water exchange is known to affect signal intensity on contrast-enhanced MRI. This article investigated the influence of water exchange between intravascular and extravascular space to account for the discrepancy in the values of v(b) obtained with a dynamic inversion-prepared gradient echo MRI sequence and histometry in tumor and normal prostate tissue. The expected influence of water exchange on v(b) was modeled by a computer simulation of the MRI signal and compared with experimental results measured with MRI and histometry. The simulation was based on a two-compartment model indicating that v(b) may be overestimated by MRI. The magnitude of overestimation leads from 10% for the slow water exchange regime to 70% for fast water exchange. Since slow water exchange is probably predominant and even if the observed histological differences in tumor tissue are considered, an overestimation of only 15% due to water exchange is predicted by the simulation. Therefore the overestimation of tumor blood volume by MRI of 60.9% compared to histometry seems to be attributable to additional causes besides water exchange.     

Characterizing blood volume fraction (BVF) in a VX2 tumor

OBJECTIVES: Neovascular proliferation of a tumor's blood supply is an important precursor of malignant growth. Evaluation of blood volume may provide useful information for the characterization, prognosis and response of tumors to therapy. The purpose of this study was to determine and compare the blood volume of tumor tissue measured noninvasively by MRI and microbubble contrast ultrasound imaging. MATERIALS AND METHODS: Twenty-two rabbits injected with VX2 tumors were studied. The blood volume fraction in tumor and muscle tissue was obtained from MRI T(1)-weighted images using a blood-pool agent, Clariscan, and by ultrasound using Definity and pulse inversion imaging. RESULTS AND CONCLUSIONS: Similar results were obtained from MRI and ultrasound. Estimation of the blood volume in tissue in the rim of a VX2 tumor 1.5 to 5.0 cm in diameter relative to that in the surrounding muscle was (mean+/-S.D.) 3.31+/-1.43 by MRI and 2.99+/-1.83 by ultrasound. The blood volume in the tissue relative to the total tissue volume (relative blood volume fraction) measured by MRI was 13+/-4.1% in tumor versus 4+/-1.4% in muscle (P<.01). Our data also suggested that, compared to the distribution volume of an extracellular contrast agent, Gd-DTPA, Clariscan as an intravascular agent demonstrated high-quality depictions of vascular structure of the tumor.     

Mn[III] uroporphyrin I: a novel metalloporphyrin contrast agent for magnetic resonance imaging.

We have used an intracranial 9L rat brain tumor model to determine whether a novel metalloporphyrin, Mn[III] uroporphyrin I (MnUROP-I), could function as an intravenous MRI contrast agent for brain tumors. In several experiments, 24 male Fischer 344 rats were inoculated intracranially with 9L brain tumor cells. On day 15 postinoculation, animals were anesthetized and the femoral vein exposed. Prior to the intravenous injection of the contrast agent, a precontrast scan (1 Tesla in a standard head coil) was performed. Thirty min after injection of the contrast agent, a postcontrast scan was performed. Although there was only a suggestion of abnormality on the precontrast scans, the presence of tumor was visibility enhanced in the postcontrast scans. In 3 animals scanned at 24 hr postinjection, persistent tumor enhancement was demonstrated. Measured tumor sizes on the MRI scans were consistent with sizes measured at autopsy and histologically. These results demonstrate that MnUROP-I is an effective MRI contrast agent for the detection of an intracranial brain tumor in the rat model.     

Three dimensional texture analysis in MRI: a preliminary evaluation in gliomas

The discrimination of tumor boundaries from normal tissue, as well as the evaluation of tissue heterogeneity and tumor grading often continue to pose a challenge in MRI. Although yielding promising results in various fields of medical imaging, two- dimensional (2D) texture analysis in MRI has, until now, demonstrated a lack of specificity in brain tumor classification. A new three-dimensional (3D) approach using Cooccurrence Matrix analysis is proposed to increase the sensitivity and specificity of brain tumor characterization. A preliminary comparative evaluation of 2D and 3D texture analysis was performed on T(1)-weighted MRI of seven gliomas for characterization of solid tumor, necrosis, edema and surrounding white matter. With 3D compared to 2D method, a better discrimination is obtained between necrosis and solid tumor as well as between edema and solid tumor. Using both methods, peritumoral white matter overlaps with edema, but is completely separated from far homo-lateral matter. This latter shows a complete overlapping with contra-lateral matter. The 3D texture analysis approach could provide a new tool for tumor grading and treatment follow-up, as well as for surgery or radiation therapy planning.     

Sodium and proton diffusion MRI as biomarkers for early therapeutic response in subcutaneous tumors

The ability to quantitate early effects of tumor therapeutic response using noninvasive imaging would have a major impact in clinical oncology. One area of active research interest is the ability to use MR techniques to detect subtle changes in tumor cellular density. In this study, sodium and proton diffusion MRI were compared for their ability to detect early cellular changes in tumors treated with a cytotoxic chemotherapy. Subcutaneous 9L gliosarcomas were treated with a single dose of 1,3-bis(2-chloroethyl)-1-nitrosourea. Both sodium and diffusion imaging modalities were able to detect changes in tumor cellularity as early as 2 days after treatment, which continued to evolve as increased signal intensities reached a maximum approximately 8 days posttreatment. Early changes in tumor sodium and apparent diffusion coefficient values were predictive of subsequent tumor shrinkage, which occurred approximately 10 days later. Overall, therapeutical induced changes in sodium and diffusion values were found to have similar dynamic and spatial changes. These findings suggest that these imaging modalities detected similar early cellular changes after treatment. The results of this study support the continued clinical testing of diffusion MRI for evaluation of early tumor treatment response and demonstrate the complementary insights of sodium MRI for oncology applications.     

Ex vivo MRI in extracorporeal liver surgery

Extracorporeal resection of hepatic tumors that were considered inoperable in the past is now possible in selected cases. Such procedures require high-quality preoperative images for the exact delineation of the tumor extent and for an optimal planning of the line of parenchymal division. In-vivo CT and MRI can not always depict the tumor adequately. In such cases, ex-vivo MRI may be a useful additional technique. It combines a high spatial resolution with the best possible soft tissue contrast, as was learned from previous studies on donor livers destined for transplantation. Ex-vivo MRI favours both a sufficiently radical resection as well as sufficient hepatic functional reserve to be present for reimplantation. A case history is reported together with details on the technical procedure.     

Quantitation of treatment volumes from CT and MRI in high-grade gliomas: implications for radiotherapy.

Long-term survival of patients with high-grade gliomas remains extremely poor. The main reason for such an outcome is local failure, or recurrence, after surgery and/or radiotherapy. Higher doses of radiation may result in decreased local failure rates provided that the location (and extent) of gross tumor and microscopic disease can be defined accurately. The abnormalities appearing in images from diagnostic modalities, such as CT and MRI, are being used as a starting point and as a guide for the clinical definition of tumor and its extensions. However, some recent studies on two-dimensional specimens, correlating histopathological findings to CT and MRI images, showed that the resulting definition of tumor cell extensions was unsatisfactory, different, and in need of ample margins. We carried out a retrospective analysis to compare the target volumes that would have been defined by CT, T2-weighted MRI, and T1-weighted postgadolinium MRI images of the same individual and to explore the implications of the resulting volume definitions for radiotherapy. The results of our limited study, based on the margins used, indicate that the CT-defined target volume is consistently larger than that from either of the two MRI modalities and suggest that noncoplanar approaches for its treatment and other local approaches for tumor boost should be considered. We conclude that until more definitive histopathological guidelines correlated to image features have been formulated and agreed upon, one should try to make full use of all available diagnostic information in order to minimize the possibility of geographical miss of target extensions.     

Adult mesoblastic nephroma: appearances on magnetic resonance imaging

Mesoblastic nephroma presenting in an adult is extremely unusual. The magnetic resonance imaging (MRI) appearances of this tumor in adulthood have not been widely reported. We present a 55-year-old patient who was diagnosed with this rare neoplasm and describe the MRI findings.     

Plexiform neurofibroma of the pelvis: CT and MRI findings

We present a case of plexiform neurofibroma of the pelvis in a patient with neurofibromatosis using magnetic resonance imaging (MRI) with computed tomography (CT) correlation. We discovered an extensive pelvic mass with a slightly greater signal intensity than muscle in T1-weighted images and a marked increased signal intensity in T2-weighted images. Multiple hypointense septations were identified throughout the tumor, particularly in the T2-weighted images. The MR appearance of pelvic plexiform neurofibroma is identical to those found in spinal and paraspinal locations. In the presence of an extensive pelvic mass in a patient with neurofibromatosis, MRI is recommended in evaluating and diagnosing plexiform neurofibroma. Since the MRI appearance of this tumor is characteristic, other lesions can possibly be ruled out. In addition, MRI's multiplanar capability is ideally suited to demonstrate the extension of these large tumors.     

Comparison of diffusion tensor,dynamic susceptibility contrast MRI and Tc-Tetrofosmin brain SPECT for the detection of recurrent high-grade glioma

Introduction

Treatment induced necrosis is a relatively frequent finding in patients treated for high-grade glioma. Differentiation by imaging modalities between glioma recurrence and treatment induced necrosis is not always straightforward. This is a comparative study of diffusion tensor imaging (DTI), dynamic susceptibility contrast MRI and ^99mTc-Tetrofosmin brain single-photon emission computed tomography (SPECT) for differentiation of recurrent glioma from treatment induced necrosis.

Methods

A prospective study was made of 30 patients treated for high-grade glioma who had suspected recurrent tumor on follow-up MRI. All had been treated by surgical resection of the tumor followed by standard postoperative radiotherapy with chemotherapy. No residual tumor had been found on brain imaging immediately after the initial treatment. All the patients were studied with dynamic susceptibility contrast brain MRI and, within a week, ^99mTc-Tetrofosmin brain SPECT.

Results

Both ^99mTc-Tetrofosmin brain SPECT and dynamic susceptibility contrast MRI could discriminate between tumor recurrence and treatment induced necrosis with 100% sensitivity and 100% specificity. An apparent diffusion coefficient (ADC) ratio cut-off value of 1.27 could differentiate recurrence from treatment induced necrosis with 65% sensitivity and 100% specificity and a fractional anisotropy (FA) ratio cut-off value of 0.47 could differentiate recurrence from treatment induced necrosis with 57% sensitivity and 100% specificity. A significant correlation was demonstrated between ^99mTc-Tetrofosmin uptake ratio and rCBV (P = 0.003).

Conclusions

Dynamic susceptibility contrast MRI and brain SPECT with ^99mTc-Tetrofosmin had the same accuracy and may be used to detect recurrent tumor following treatment for glioma. DTI also showed promise for the detection of recurrent tumor, but was inferior to both dynamic susceptibility contrast MRI and brain SPECT.     

Diagnostic utility of tumor vascularity on magnetic resonance imaging of the breast

The objective of this study was to examine the relation of tumor vascularity on magnetic resonance imaging (MRI) with differential diagnosis malignant from benign lesions and tumor invasiveness in breast carcinoma. Forty-nine patients with breast cancer or benign lesion (median 49 yrs) were examined with dynamic MRI. Scanning of the entire breast was performed at 1.5 T with a three-dimensional fast spin echo sequence, using an original polarity altered spectral and spatial selective acquisition (PASTA) technique for fat suppression. Subsequently 0.1 mmol/Kg Gd-DTPA was administered and 3-6 images were obtained. The presence or absence of intratumoral, marginal and peritumoral vascularity on MRI was recorded. The excised specimen was histopathologically examined for the size of lesion, the presence and extent of local invasion. Tumor size on MRI correlated closely with the size at morphologic examination (r = 0. 96). Intratumoral (p = 0.04), marginal (p = 0.05) and peritumoral vascularity (p = 0.01) were less common in benign than in malignant lesions. Among the latter, intratumoral (p = 0.01) and marginal (p = 0.03) vascularity were more common in invasive carcinomas than in DCIS. In the subset of invasive carcinomas (n = 31); however, the tumors exhibiting intratumoral vascularity were markedly larger (p = 0.03). The presence of intratumoral and marginal vascularity on MRI can help predict both the differential diagnosis malignant from benign lesions and the presence tumor invasion in breast carcinomas.     

MRI in staging of endometrial and cervical carcinoma

MRI of 54 patients with endometrial and cervical carcinoma was performed on a 0.6-T superconducting magnet. In 18 of 24 cases of surgically proved endometrial carcinoma, MRI accurately showed the depth of myometrial invasion. MRI was superior to CT scan for defining the primary site and extent of the tumor in 14 of 24 cases. Of 25 patients with cervical carcinoma studied, MRI was superior to CT scan in 15 of 19 cases with CT correlation for localizing the primary site. MRI showed parametrial extension and invasion of surrounding structures but is probably less reliable than CT scan for detection of adenopathy because of false positive findings from volume averaging with bowel.     

A reference agent model for DCE MRI can be used to quantify the relative vascular permeability of two MRI contrast agents

Dynamic Contrast Enhancement (DCE) MRI has been used to measure the kinetic transport constant, K^trans, which is used to assess tumor angiogenesis and the effects of anti-angiogenic therapies. Standard DCE MRI methods must measure the pharmacokinetics of a contrast agent in the blood stream, known as the Arterial Input Function (AIF), which is then used as a reference for the pharmacokinetics of the agent in tumor tissue. However, the AIF is difficult to measure in pre-clinical tumor models and in patients. Moreover the AIF is dependent on the Fahraeus effect that causes a highly variable hematocrit (Hct) in tumor microvasculature, leading to erroneous estimates of K^trans. To overcome these problems, we have developed the Reference Agent Model (RAM) for DCE MRI analyses, which determines the relative K^trans of two contrast agents that are simultaneously co-injected and detected in the same tissue during a single DCE-MRI session. The RAM obviates the need to monitor the AIF because one contrast agent effectively serves as an internal reference in the tumor tissue for the other agent, and it also eliminates the systematic errors in the estimated K^trans caused by assuming an erroneous Hct. Simulations demonstrated that the RAM can accurately and precisely estimate the relative K^trans (R^Ktrans) of two agents. To experimentally evaluate the utility of RAM for analyzing DCE MRI results, we optimized a previously reported multiecho ¹⁹F MRI method to detect two perfluorinated contrast agents that were co-injected during a single in vivo study and selectively detected in the same tumor location. The results demonstrated that RAM determined R^Ktrans with excellent accuracy and precision.     

叶酸偶联磁性白蛋白纳米球的体内外靶向性评价

该文从体内外水平,探讨叶酸偶联磁性白蛋白纳米球对人鼻咽癌细胞KB的靶向效应. 体外实验中,将叶酸靶向、非叶酸靶向和叶酸抑制组与人鼻咽癌细胞KB共孵育24 h后,通过普鲁士蓝染色、7.0 Tesla Micro-MR仪检测叶酸受体介导的靶向效应;体内试验中,首先建立裸鼠荷人鼻咽癌细胞KB皮下移植瘤动物模型,再通过MRI检测及病理组织学检查,评价叶酸偶联磁性白蛋白纳米球的靶向性. 体外MRI成像显示叶酸靶向组与人鼻咽癌细胞KB共孵育后T₂WI信号强度降低,普鲁士蓝染色则显示靶向组细胞内存在大量铁颗粒;在体MRI成像结果显示,注射材料后不同时间点叶酸靶向组的T₂WI、T*₂-WI强度有明显下降,具有统计学差异. 病理学检查显示叶酸靶向组肿瘤组织内有较多蓝染的铁颗粒,而非靶向组和叶酸抑制组则未见铁颗粒的存在. 体内外实验均表明叶酸偶联磁性白蛋白纳米球对人鼻咽癌细胞KB具有良好的靶向性.     

Asymptomatic adult cystic lymphangioma of the spleen: case report and review of the literature

In the present report we describe a case of an asymptomatic splenic cystic lymphangioma in a 43 year-old female. Only a few cases of this benign tumor have been reported in adult patients so far. Clinical examination revealed a tender mass in the upper left quadrant of the abdomen. Abdominal ultrasound and CT-scan revealed a large well-defined splenic cystic mass surrounded by multiple peripheral cysts, all divided by thin septa. MRI confirmed these findings and excluded the possibility of malignant degeneration. Histologic examination permitted the accurate diagnosis to be made. Different imaging findings of this tumor have been described but only a few reports have focused on the value of MRI imaging.     

Primary left atrial angiosarcoma: follow-up by magnetic resonance imaging

We report the case of a primary left atrial angiosarcoma followed by MRI over a period of 1 year. The tumor was lobulated, with an initial central hyperintensity on T1-weighted images which disappeared after radiotherapy. Compared with other imaging modalities, MRI offered the most accurate information about the location, extent, and outcome under treatment.     

Histopathological analysis of a bladder cancer stalk observed on MRI

Papillary transitional cell carcinoma of the bladder has a loose connective tissue stalk. For staging of bladder cancer on magnetic resonance imaging (MRI), it is important to clearly separate the cancer from the bladder wall. It is possible to distinguish a stalk from the cancer by the difference of intensity on the using MRI. Sixteen stalks of 20 polypoid bladder tumors on any of the T(2)W(I), dynamic images and delayed enhanced images were demonstrated. Most of the stalks show lower signal intensity than the tumors on T(2)W(I), less enhancement on dynamic images and stronger enhancement on delayed enhanced images. The stalk consisted of fibrous connective tissue, capillary blood vessels, inflammatory cell infiltration and edema. This stalk extended from the bladder wall to the center of the tumor. Some of the superficial muscular bundles were pulled into the stalk. These histopathological findings were compatible with the patterns of signal intensities on MRI. The identification of the stalk of a polypoid tumor may be an important observation to exclude bladder wall invasion by tumor.     

Validation of optimal DCE-MRI perfusion threshold to classify at-risk tumor imaging voxels in heterogeneous cervical cancer for outcome prediction

Purpose

To classify tumor imaging voxels at-risk for treatment failure within the heterogeneous cervical cancer using DCE MRI and determine optimal voxel's DCE threshold values at different treatment time points for early prediction of treatment failure.

Material and Method

DCE-MRI from 102 patients with stage IB2–IVB cervical cancer was obtained at 3 different treatment time points: before (MRI 1) and during treatment (MRI 2 at 2–2.5 weeks and MRI 3 at 4–5 weeks). For each tumor voxel, the plateau signal intensity (SI) was derived from its time-SI curve from the DCE MRI. The optimal SI thresholds to classify the at-risk tumor voxels was determined by the maximal area under the curve using ROC analysis when varies SI value from 1.0 to 3.0 and correlates with treatment outcome.

Results

The optimal SI thresholds for MRI 1, 2 and 3 were 2.2, 2.2 and 2.1 for significant differentiation between local recurrence/control, respectively, and 1.8, 2.1 and 2.2 for death/survival, respectively.

Conclusion

Optimal SI thresholds are clinically validated to quantify at-risk tumor voxels which vary with time. A single universal threshold (SI = 1.9) was identified for all 3 treatment time points and remained significant for the early prediction of treatment failure.