Intracranial meningiomas: correlations between MR imaging and histology.

The authors have examined the relationship between magnetic resonance imaging (MRI) and histopathological features in 35 surgically verified intracranial meningiomas. Tumor signals on T1-weighted images were rather similar regardless of the histologic subtype of the tumors. On T2-weighted images, hypointense meningiomas were mainly fibroblastic and hyperintense tumors were mainly syncytial and angioblastic, and partly transitional. Isointense tumors were mainly transitional and partly fibroblastic and syncytial. The authors conclude that the signal intensity of the MRI may be useful in the preoperative characterization of intracranial meningiomas. T1-weighted images may predict the presence of cysts and intratumoral blood vessels; whereas T2-weighted images can give information about histological subtype, vascularity and consistency. Meningiomas hyperintense to the cortex on T2 are usually soft, more vascular and more frequently of syncytial or angioblastic subtype; tumors hypointense or hypo-isointense on T2 tend to have a more hard consistency and are more often of fibroblastic or transitional subtype.     

脑膜瘤的MRI表现与组织病理对照研究

目的　研究脑膜瘤的磁共振表现与其病理分类之间的关系。方法　回顾分析 12 8例经手术病理证实为脑膜瘤患者的MRI表现。结果　T1WI图像 ,上皮型脑膜瘤 2 9例 ( 4 9% )呈低信号 ,11例 ( 19% )呈稍低信号 ,17例 ( 2 9% )呈等信号。而纤维型脑膜瘤T1WI信号类型分别为 2 3例 ( 5 9% ) ,5例 ( 13 % )和 9例 ( 2 3 % )。在T2 WI图像上 ,3 4例 ( 5 8% )上皮型脑膜瘤呈高信号 ,15例 ( 2 5 % )呈稍高信号 ,10例 ( 17% )呈等信号 ,而纤维型分别为 2例 ( 5 % ) ,8例 ( 2 0 .5 % )和 11例 ( 2 8% )。上皮型、纤维型、移行型在T1WI上均呈现等、低信号 ,而在T2 WI图像上 ,上皮型、血管瘤型及移行型呈现为高信号或稍高信号 ;纤维型脑膜瘤T1WI以低或稍低信号为主。结论　在MRIT1WI图像上 ,各组织学类型之间信号强度的分布无显著性差别 ,而在T2 WI上 ,信号强度与病理类型具有统计学的相关性     

Phyllodes tumor of the breast: correlation between MR findings and histologic grade

PURPOSE: To retrospectively evaluate the magnetic resonance (MR) imaging findings of phyllodes tumor of the breast and to compare these findings with the histologic grade. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. The authors reviewed the MR findings in 30 female patients aged 16-73 years (mean, 40.2 years) with surgically confirmed phyllodes tumors. Analyzed MR findings included tumor shape, margin, internal enhancement, and size; signal intensity (SI) of tumor higher than that of normal breast tissue on T1-weighted images; SI of tumor lower than or equal to that of normal tissue on T2-weighted images; cyst wall appearance; kinetic curve assessment; and apparent diffusion coefficient (ADC). The MR findings and histologic grade were statistically analyzed to determine whether any correlations existed. Significant MR findings were compared with histopathologic findings. RESULTS: Nineteen benign, six intermediate (characterized by five to nine cell reproductions at 10 high-power fields, pushing or infiltrative margins, moderate stromal cellularity, and atypia and overgrowth), and five malignant phyllodes tumors were assessed. Irregular cyst wall (P = .003), tumor SI lower than or equal to normal tissue SI on T2-weighted images (P = .005), and low ADC (P = .001) correlated significantly with histologic grade. Tumor SI higher than normal tissue SI on T1-weighted images was more frequent in the malignant (in three of five tumors) and intermediate (in three of six tumors) groups than in the benign group (in two of 19 tumors); however, it was not a significant finding (P = .024). Tumor SI higher than normal tissue SI on T1-weighted images and irregular cyst wall corresponded histopathologically to hemorrhagic infarction and necrosis, respectively. Tumor SI lower than or equal to normal tissue SI on T2-weighted images and low ADC corresponded histopathologically to stromal hypercellularity. Other findings were not significant. CONCLUSION: Several MR findings can be used to help determine the histologic grade of phyllodes breast tumors.     

MR imaging of liposarcomas: correlation of MR features and histology

The magnetic resonance (MR) imaging features of liposarcoma were correlated with histology in 15 patients. The MR findings for liposarcoma were not specific. The six myxoid liposarcomas and two atypical lipomatous tumors, however, had distinctive MR features, i.e., nodular masses of slightly heterogeneous intermediate to high signal intensity (SI), intermingled with high SI septa on T1-weighted images. The T2-weighted images demonstrated the relative reversal of these regional SI characteristics. Additionally, MR correctly identified the presence of fat in all eight cases in which it was pathologically present. The fat in two atypical lipomatous tumors was inseparable on MR from the subcutaneous fat. Magnetic resonance appears useful for preoperative staging and follow-up studies of liposarcomas. It may be helpful in identifying patients with myxoid liposarcoma and atypical lipomatous tumors who have longer survival times.     

Malignant lesions of the liver with high signal intensity on T1-Weighted MR images

Our purpose was to identify the histologic types of malignant liver lesions with high signal intensity (SI) on T1-weighted images and to describe the MR imaging features. Thirteen patients with malignant liver lesions high in SI on T1-weighted images were studied with a 1.5-T MR imager using pre- and serial postcontrast spoiled gradient-echo (SGE) sequences (all patients), T2-weighted fat-suppressed spin-echo sequences (all patients), precontrast T1-weighted fat-suppressed spin-echo sequences (five studies in five patients), and precontrast out-of-phase SGE sequences (seven studies in six patients). Images were reviewed retrospectively to determine number of lesions; lesion size; SI of lesions on T1-weighted, T2-weighted, and fat-attenuated T1-weighted images; distribution of high SI in lesions on T1-weighted images; and tumor enhancement pattern. Seven patients had multiple tumors high in SI on T1-weighted images and six patients had solitary tumors. Seventy-two lesions were less than 1.5 cm in diameter and 35 lesions were more than 1.5 cm in diameter. Nine patients had solid malignant lesions and four patients had cystic malignant lesions. All tumors more than 1.5 cm in diameter were heterogeneously high in SI on T1-weighted images, and all tumors less than 1.5 cm were completely homogeneous or homogeneous with a small central hypointense focus. All tumors were more conspicuous on T1-weighted fat-attenuated images, both on excitation spoiled fat-suppressed spin-echo or on out-of-phase SGE images with the exception of one fat-containing hepatocellular carcinoma (HCC). In one patient with melanoma metastases and one patient with multiple myeloma nodules, appreciably more lesions were detected on out-of-phase SGE images. Causes of hyperintensity were considered to be either fat, melanin, central hemorrhage, or high protein content, all of which may be seen in a variety of tumors. Fat-attenuation techniques are helpful in the detection of these lesions.     

Case report: magnetic resonance imaging of vaginal malignant melanoma

We report two cases of vaginal melanoma with magnetic resonance imaging findings. The first melanoma was a bilobular polypoid mass with melanotic and amelanotic components, which arose from the lateral wall of the vaginal canal. The melanotic melanoma showed high signal intensity (SI) on T1-weighted images and low SI on T2-weighted images, which was not suppressed by a fat-saturated sequence. Another melanoma showed a pale brown polypoid mass in the vagina, which revealed intermediate SI on T1-weighted images and high SI on T2-weighted images. On fat-suppressed images, both tumors were more clearly demonstrated with high SI.     

Multiple myeloma: appearance at MR imaging.

Magnetic resonance (MR) imaging examinations of the lumbar spine and clinical and laboratory findings in 32 patients with multiple myeloma were reviewed. On T1-weighted images, signal intensity (SI) of the vertebrae approximated that of muscle in 14 cases and was intermediate (between the SIs of muscle and fat) in 18. Definite foci of decreased SI were seen in eight cases (25%), and foci of increased SI, representing fatty infiltration, were seen in 12 (38%). On T2-weighted images, SI approximated that of muscle in 17 cases and was intermediate in 15. Definite foci of increased SI were seen in 17 (53%). Of 38 vertebral compression fractures (including 18 in nine additional patients), foci of abnormal SI consistent with tumor on either T1- or T2-weighted images were seen in 19 cases (50%). There was no correlation between MR imaging findings and laboratory or bone marrow findings. Foci of presumed tumor were better or exclusively shown on T2-weighted images in 11 of 17 patients (65%) with identifiable focal disease. Other suggestions of multiple myeloma on T1-weighted images may be the absence of fatty replacement or a generalized decrease in SI.     

Mucinous versus nonmucinous rectal carcinomas: differentiation with MR imaging.

PURPOSE: To determine if quantitative and qualitative magnetic resonance (MR) imaging measures can help differentiation of mucinous from nonmucinous rectal tumors. MATERIALS AND METHODS: In 26 patients with pathologically proved mucinous (n = 9) and nonmucinous (n = 17) rectal tumors, MR imaging was performed with T1-weighted spin-echo (SE) and T2-weighted fast SE sequences in all patients and with a gadolinium-enhanced T1-weighted sequence in 18. With use of the signal intensity (SI) measurements in the tumors and reference tissues, tumor-to-muscle, tumor-to-fat, and tumor-to-urine SI ratios were calculated. In addition, the SI and contrast-enhancement patterns in the tumors were assessed qualitatively by three blinded readers. RESULTS: Mucinous tumors had a much higher SI on the T2-weighted fast SE images. Tumor-to-muscle, tumor-to-fat, and tumor-to-urine SI ratios were significantly higher in the mucinous compared with the nonmucinous tumors (P = .0004, P = .0008, and P = .00002, respectively). Qualitative evaluation of the SI correlated well between readers 1 and 2 (r = 0.93), readers 1 and 3 (r = 0.94), and readers 2 and 3 (r = 0.91). Agreement for the contrast-enhancement patterns was 67%, 72%, and 67%, respectively, with most mucinous tumors having predominantly high SI and a peripheral contrast-enhancement pattern. CONCLUSION: Mucinous and nonmucinous rectal tumors can be differentiated with MR imaging because mucinous tumors show high SI on T2-weighted fast SE images.     

MRI of ganglioneuroma: histologic correlation study

PURPOSE: The purpose of this study was to evaluate the MR findings of ganglioneuroma and to correlate imaging and histologic features. METHOD: Conventional SE and contrast-enhanced dynamic MRI was used to examine 10 patients with pathologically confirmed ganglioneuroma. The morphologic features, signal intensity, and dynamic enhancement pattern of the tumors were retrospectively analyzed and correlated with histologic features. RESULTS: Capsules were present in all tumors histologically and were also detected in five tumors on postcontrast T1-weighted images. A whorled appearance corresponding to interlacing bundles of Schwann cells and collagen fibers on histologic specimens was visualized in five tumors on T1-and/or T2-weighted images. Tumors with markedly high signal intensity on T2-weighted images consisted histologically of a large amount of myxoid stroma and relatively few cellular and fibrous components. Tumors with intermediate to high signal intensity consisted of numerous cellular and fibrous components and little myxoid stroma. Early enhancement of tumors was usually lacking in dynamic MR studies; however enhancement gradually increased. CONCLUSION: The results suggest that the MR features of ganglioneuroma are well correlated with histologic findings.     

Hepatocellular carcinoma: correlation of MR imaging and histopathologic findings.

Seventy-two histologically proved nodular hepatocellular carcinomas (HCCs) were studied with magnetic resonance (MR) imaging at 1.5 T. Capsules were present in 56 of the 72 tumors. Thirty-seven capsules were depicted on T1-weighted spin-echo MR images, and 16 were depicted on T2-weighted MR images. Visualization was dependent on thickness and structure of the capsules. Of the 72 tumors, 36 had a mosaic pattern. A mosaic pattern was visualized in 12 of the 36 tumors on T1-weighted images and in 27 of the 36 tumors on T2-weighted images. Six tumors were determined to be histologic grade 1, and all were hyperintense on T1-weighted images, regardless of whether intracellular fat deposits were present. Four of the six grade 1 tumors were isointense on T2-weighted images. In contrast, grades 2 and 3 tumors had various signal intensities on T1-weighted images and most were hyperintense on T2-weighted images. Twenty-one of 32 tumors (66%) with focal areas of increased signal intensity on T2-weighted images had intratumoral dilated sinusoids at histologic examination.     

MR imaging of tuberculous arthritis: Clinical and experimental studies

Signal-intensity characteristics of magnetic resonance (MR) images were assessed in five patients and in 10 rabbits with tuberculous arthritis. MR imaging findings were compared with histologic findings in the animal study. In both of clinical and experimental cases, tuberculous lesions showed both intermediate and high signal intensity on T2-weighted images, while they showed heterogeneously intermediate signal intensity on T1-weighted images. As T2-weighted images were compared with pathologic specimens, intermediate signal intensity corresponded to caseous necrosis, whereas high signal intensity related to granulomas or effusion. Postcontrast T1-weighted images showed enhancement at the peripheries rather than the centers of tuberculous lesions. These results indicate that tuberculous arthritis should be included in the differential diagnosis when intra-articular lesions with low or intermediate signal intensity are found on T2-weighted images.     

Variable MR findings in ovarian functional hemorrhagic cysts

PURPOSE: To describe the magnetic resonance (MR) findings in ovarian functional hemorrhagic cysts (FHC). MATERIALS AND METHODS: A total of 21 patients with 22 FHC, proven by follow-up ultrasound (US) in 11 women and surgery in 10 women, had US and MR examinations within 24 hours. The study was limited to cysts with obvious an echogenic pattern. All patients had T2-weighted fast spin echo (FSE), T1-weighted spin echo (SE), and T1-weighted SE fat-suppressed sequences. RESULTS: Four cysts (18%) were hypointense on T1-weighted-images without and with fat suppression, and hyperintense on T2-weighted-images. Five cysts (23%) were hypointense on T1-weighted images without and with fat suppression but heterogenous on T2-weighted images. Five cysts (23%) were hypointense on T1-weighted images but showed intermediate signal intensity on T1-weighted fat suppression images and heterogenous signal intensity on T2-weighted images. Two cysts (9%) were entirely intermediate on T1-weighted images. Five cysts (23%) displayed high signal intensity occupying less than 30% of the cystic content on T1-weighted images and one cyst (5%) displayed high signal intensity occupying more than 30% of the cystic content. CONCLUSION: Despite an obvious echogenic pattern on US, 64% of FHC were hypointense on T1-weighted images and 18% were also hyperintense on T2-weighted images. Only 36% demonstrated intermediate or high signal intensity on T1-weighted images.     

Predicting the effect of gonadotropin-releasing hormone (GnRH) analogue treatment on uterine leiomyomas based on MR imaging

PURPOSE: To test the hypothesis that the simple assessment of signal intensity on T2-weighted MR images is predictive of the effect of hormonal treatment with gonadotropin-releasing hormone (GnRH) analogue. MATERIAL AND METHODS: The correlation between T2-weighted MR imaging of uterine leiomyomas and histologic findings was evaluated using 85 leiomyomas from 62 females who underwent myomectomy or hysterectomy. We also correlated the pretreatment MR images features obtained in 110 women with 143 leiomyomas with the effect of GnRH analogue treatment. The size (length x width x depth) of the leiomyoma was evaluated before and at 6 months after treatment by ultrasound. RESULTS: The proportion of leiomyoma cell fascicles and that of extracellular matrix affected signal intensities of uterine leiomyomas on T2-weighted MR images. The amount of extracellular matrix was predominant in hypointense leiomyomas on T2-weighted images, while diffuse intermediate signal leiomyomas were predominantly composed of leiomyoma cell fascicles. Marked degenerative changes were noted in leiomyomas with heterogenous hyperintensity. The homogeneously intermediate signal intensity leiomyomas showed significant size reduction after treatment (size ratio; posttreatment volume/pretreatment volume 0.29+/-0.11). The size ratio for the hypointense tumors was 0.82+/-0.14, and 0.82+/-0.18 for the heterogeneously hyperintense tumors. There was a significant difference in the response to treatment between the homogeneously intermediate signal intensity leiomyomas and the hypointense or heterogeneously hyperintense leiomyomas (both p<0.01). CONCLUSION: Signal intensity on T2-weighted MR images depends on the amount of leiomyoma cell fascicles and extracellular matrix. Simple assessment of the MR signal intensity is useful in predicting the effect of GnRH analogue on uterine leiomyomas.     

Vertebral hemangiomas: MR imaging

Vertebral hemangiomas, unlike most bone lesions, show increased signal on T1- and T2-weighted magnetic resonance (MR) images. To define the basis for these signal characteristics, a retrospective review was done of the MR imaging findings in ten vertebral hemangiomas (eight patients), and these were correlated with the findings from plain radiographic, computed tomographic (CT), and histopathologic studies. MR images showed mottled increased signal in T1- and T2-weighted images from the osseous portions of the tumors. In three patients, the extraosseous components failed to show increased signal on T1-weighted images. Chemical shift images and histologic studies demonstrated that adipose tissue caused the increased signal on T1-weighted images. The extraosseous components of the tumor contained little, if any, adipose tissue, which explained the lack of high-intensity signal on T1-weighted images. These signal changes appear to make a specific constellation of findings for the diagnosis of vertebral hemangioma with MR imaging.     

Uptake of mangafodipir trisodium in liver metastases from endocrine tumors

The purpose of the study was to investigate retrospectively whether mangafodipir trisodium (MnDPDP) can enhance the liver metastases from endocrine tumors. Thirteen patients with endocrine tumors and liver metastases underwent T1-weighted spin-echo (SE) and turbo gradient-echo (GRE) MRI conducted before and 20 to 60 minutes after iv infusion of MnDPDP. Additional 24-hour-delay scans were performed in 8 of 13 patients. MR signal intensity (SI) was measured in liver parenchyma and metastases, which was then related to that of paraspinal muscle. A total of 30 lesions on precontrast and postcontrast images and 18 lesions on 24-hour-delay images were measured. An enhancement by 49% in SE and 40% in GRE images (P = .0001) was observed in tumor tissues after MnDPDP infusion. In 24-hour-delay images, the SI of the lesions remained relatively high, but in liver parenchyma, it decreased significantly, and the tumor-liver tissue contrast was reduced.     

Suspected recurrent rectosigmoid carcinoma after abdominoperineal resection: MR imaging and histopathologic findings

Eleven patients who underwent abdominoperineal resection for rectosigmoid carcinoma were examined with magnetic resonance (MR) imaging for suspected recurrent tumor in the presacral space. There were 12 suspected masses in the 11 patients. Ten lesions were malignant, and in two lesions only nonneoplastic inflammatory tissue was found. The signal intensity (SI) of each lesion relative to that of muscle was determined visually and correlated with the histologic findings at surgery or biopsy. The SIs of malignant and benign lesions were indistinguishable. All lesions showed areas of high SI that correlated with carcinoma and tumor necrosis or with non-neoplastic inflammation and edema. Areas of low SI corresponded to reactive fibrous tissue (desmoplastic reaction) with small islands of tumor or to nonneoplastic fibrosis. MR imaging can be useful in determining the extent of suspected tumors, but SIs on T2-weighted images do not permit histologic diagnosis. In particular, distinction of benign from malignant tissue is difficult in tumors with a desmoplastic reaction.     

Sinonasal tumors and inflammatory tissues: differentiation with MR imaging

The magnetic resonance (MR) and computed tomographic (CT) images of 53 patients with sinonasal tumors were analyzed and compared for accuracy in tumor mapping. the findings were confirmed by means of either surgery or biopsy. The MR images of 60 patients with inflammatory disease were also studied, and the findings were confirmed at surgery. Forty-seven additional MR images were also examined of patients with tumors showing histologic characteristics similar to those found in the sinonasal tumor group but occurring elsewhere in the head and neck, excluding the orbit. This study concludes that nearly 95% of sinonasal tumors have an intermediate T2 signal, while only 5% have bright T2 signals. This small latter group is composed almost exclusively of some minor salivary gland tumors and some neuromas. The inflammatory tissues all had bright T2 signals. The distinction between sinonasal tumors and inflammatory tissues was best accomplished with T2-weighted studies, and MR imaging was more accurate than CT.     

Dynamic MRI of meningiomas and schwannomas: is differential diagnosis possible?

We studied 23 patients with meningiomas and 14 with schwannomas using dynamic spin-echo (TR/TE 200/15 ms) MRI. Histologically the meningiomas were classified according to the 1993 WHO classification. Serial images were obtained every 30 s for 210 s after rapid injection of gadopentetate dimeglumine (0.1 mmol/kg). The contrast-enhancement ratio (CER) was divided into three patterns; a sharp rise with a peak within 60 s (A), a relatively rapid increase with a peak between 60 and 210 s (B), a slow increase without a peak (C). The patterns were correlated with the histology of the tumors. The signal intensities of the tumours on T2-weighted images were also analyzed and correlated with the dynamic patterns. Meningiomas had more varied dynamic patterns than schwannomas. Almost half of the meningiomas showed pattern A, and one third pattern C. Of six meningothelial meningiomas showed pattern A; all schwannomas and fibrous meningiomas showed pattern C. Various patterns were observed in transitional meningiomas. Of the 8 meningiomas showing pattern C, only one gave high signal on T2-weighted images, and could not be differentiated from the schwannomas. Thus, one third of meningiomas could not be differentiated from schwannomas by the dynamic contrast enhancement alone. However, when this was combined with the signal intensity on T2-weighted images, most meningiomas could be differentiated from schwannomas. Received: 17 June 1996 Accepted: 11 October 1996     

Correlation of MR imaging and histologic findings in mouse melanoma.

M2R melanoma tumors in male C57 black mice were used to correlate magnetic resonance (MR) images with the corresponding histologic slices and to determine if analysis of the achievable correlation can provide a basis for predicting gross histologic features with MR imaging alone. The MR imaging sections obtained at 4.7 T were each 680 microns thick, with an in-plane resolution of 195 microns. The distribution of melanin within the histologic slices correlated well with the high-signal-intensity regions on the T1-weighted images (T1WIs), while these regions had low signal intensity on the T2-weighted images (T2WIs), providing evidence that melanin or melanin-associated paramagnetic species are responsible for the observed proton relaxation rate enhancement. Viable melanoma cells typically showed intermediate signal intensity on T2WIs, T1WIs, and proton-density images. Necrosis typically had high signal intensity on T2WIs, T1WIs, and proton-density images. Quantitation of the MR imaging results, followed by statistical analysis, demonstrated statistically significant differences between melanin-rich, viable-melanoma, and necrotic regions on MR images.     

Diffusion-weighted imaging of a malignant brenner tumor

Microscopically, ovarian malignant Brenner tumor shows components of malignant transitional cell tumor intermixed with benign and borderline elements. We report a case of this tumor with components that transition from benign to malignant on diffusion-weighted images (DWI) and in histologic findings. The benign component showed low signal intensity on T(2)-weighted images, whereas the malignant component showed high signal intensity on T(2)-weighted images and high signal intensity on DWI with low apparent diffusion coefficient (ADC) value.