Epithelial tumors of the ovary: comparison of MR and CT findings

Forty patients with 50 ovarian epithelial tumors of the ovary were retrospectively studied. They underwent computed tomography and magnetic resonance (MR) imaging within 1 week of surgery. MR examinations were performed with a superconducting magnet (0.5 T) and predominantly T1- and T2-weighted MR imaging. T1-weighted MR images were obtained in eight patients after contrast material was administered. Signal intensity of tumors was compared with that of urine, muscle, and fat. Morphologic features that were evaluated included size, vegetations, septations, wall thickness, fluid or solid components, and vascularity. On the basis of signal intensity and morphologic characteristics, MR imaging helped in the correct diagnosis of benign serous cystadenoma in 10 of 13 tumors, benign mucinous cystadenoma in seven of 10 tumors, and tumors of low malignant potential and malignant tumors in 23 of 27 tumors. Accuracy for overall characterization of benign versus malignant tumors was 86% with MR imaging and 92% with computed tomography. There was no difference in sensitivity (P = 1) or specificity (P = .5).     

MR imaging of extraabdominal desmoids: differentiation from other neoplasms.

A retrospective review of MR images of 36 patients with histologically proved extraabdominal desmoids was done to define the MR characteristics of these tumors and to determine if MR could be used to differentiate desmoids from other benign and malignant soft-tissue neoplasms. The desmoids evaluated included eight primary and 30 recurrent lesions. Our study was conducted in parallel with another study in which the MR appearance of 95 benign and malignant soft-tissue masses was evaluated, and the MR images of these masses were compared with our findings. The four desmoids from that study are included in our data. The signal intensity of the tumor on T1- and T2-weighted images was graded relative to the intensities of muscle and fat. Homogeneity, margin, neurovascular and bone involvement, and fibrosis (low-signal regions within the tumor on both T1- and T2-weighted images) were evaluated. On MR imaging, the desmoids showed inhomogeneous signal (97%), poor margination (89%), neurovascular involvement (58%), and bone involvement (37%). Fibrosis was present in 88% of primary desmoids and 90% of recurrent ones, and intermediate signal (greater than that of muscle and less than that of fat) was present in 75% and 50% of these, respectively. Our results show that the MR features of desmoids have characteristics that are commonly found in malignant tumors (inhomogeneous signal, poor margination, and neurovascular involvement). MR features of desmoids that distinguish them from malignant neoplasms are the presence of fibrosis and intermediate signal in the regions of the tumor.     

Malignant parotid tumors: clinical use of MR imaging and histologic correlation.

Magnetic resonance (MR) imaging was performed in 116 patients in whom a parotid mass lesion was clinically suspected. Eighty-six patients had benign disease. The 30 patients in whom a malignant tumor was found were further evaluated. To determine which features are characteristic of malignant parotid tumors, spin-echo T1- and T2-weighted images of malignant lesions in the parotid gland were compared with those of benign disease. In our series, tumor margins, homogeneity, or signal intensity were not discriminative factors to correctly predict benign or malignant disease. Infiltration into deep structures (eg, the parapharyngeal space, muscles, and bone) was observed only in malignant tumors. Infiltration into subcutaneous fat was noticed in malignant as well as in inflammatory disease. No statistically significant correlation was found between tumor grade and MR imaging features in malignant disease. MR imaging is useful in delineating malignant tumors but is unreliable in correctly predicting the histologic nature of a mass lesion in the parotid gland.     

High-spatial-resolution MR imaging of focal breast masses: interpretation model based on kinetic and morphological parameters

PURPOSE: To assess a new interpretation model combining kinetic pattern and morphologic characteristics using high-spatial-resolution MR imaging. MATERIALS AND METHODS: Breast MR imaging was performed in 58 patients with 63 pathologically proved focal breast masses (49 malignant and 14 benign). MR imaging was performed on a 1.5-Tesla system using the volumetric interpolated breath-hold examination (VIBE) sequence. Morphological parameters were lesion shape, mass margin, rim enhancement (RE), enhancing internal septations, and internal signal on T2-weighted images. Lesion shape/margin was classified into four categories as follows: smooth (smooth/round or smooth/oval), lobulated (lobular shape), irregular (irregular margin or irregular shape), and spiculated (spiculated margin). RE was sub-classified as early RE at 60 sec and delayed RE at 4 min. Strongly high signal and the presence of internal black septations were evaluated over the entire lesion on T2-weighted images. The kinetic parameter was visually assessed as follows: washout, plateau, and progressive. RESULTS: The most frequent types of lesion shape/margin in the malignant lesions were irregular (47%) and spiculated (43%), whereas 13 of the benign lesions had smooth or lobular margins (93%). The most frequent characteristics in breast cancers with lobulated configuration were washout pattern (80%), whereas 78% of the lobulated benign lesions were negative for visual washout. The positive predictive value (PPV) was 98% (49/50). CONCLUSION: "Washout with enhancing septations" is thought be specific for carcinoma with a lobulated configuration (80%). A combination of morphological criteria (including lesion shape/margins, strongly high signal on T2-weighted images) and visual washout is useful for differentiating between benign and malignant lesions.     

Granular cell tumor of the extremity: magnetic resonance imaging characteristics with pathologic correlation

Objective The purpose of this study is to delineate the magnetic resonance (MR) appearance of a granular cell tumor (GrCT) of the extremity and to correlate the imaging appearance with the microscopic findings.Design and patients A retrospective review of five patients with a histopathologic diagnosis of GrCT and pre-operative MR imaging of the neoplasm was done. The images were reviewed by two musculoskeletal radiologists in a consensus fashion. Lesion location, size, shape, margination, and signal intensity characteristics were assessed. MR findings were correlated with histopathological examination.Results The benign subtype of GrCT is usually isointense or brighter than muscle on T1-weighted sequences, round or oval in shape, superficial in location, and 4 cm or less in size. On T2-weighted sequences, benign lesions may demonstrate a high peripheral signal, as well as a central signal intensity that is isointense to muscle or suppressed fat. A significant stromal component in the tumor and, hypothetically, a ribbon-like arrangement of tumor cells may influence the signal intensity demonstrated on the T1 and T2-weighted sequences. The malignant subtype may demonstrate signal intensity characteristics and invasion of adjacent structures often seen with other aggressive neoplasms; sizes larger than 4 cm and association with major nerve trunks can be seen.Conclusion Benign GrCT has imaging characteristics which may distinguish this tumor from other soft tissue neoplasms, as well as the malignant type of this tumor.     

Warthin tumor of the parotid gland: diagnostic value of MR imaging with histopathologic correlation

BACKGROUND AND PURPOSE: The purpose of our study was to describe the MR imaging appearance of Warthin tumors multiple MR imaging techniques and to interpret the difference in appearance from that of malignant parotid tumors. METHODS: T1-weighted, T2-weighted, short inversion time inversion recovery, diffusion-weighted, and contrast-enhanced dynamic MR images of 19 Warthin tumors and 17 malignant parotid tumors were reviewed. MR imaging results were compared with those of pathologic analysis. RESULTS: Epithelial stromata and lymphoid tissue with slitlike small cysts in Warthin tumors showed early enhancement and a high washout rate (> or =30%) on dynamic contrast-enhanced images, and accumulations of complicated cysts showed early enhancement and a low washout ratio (< 30%). The areas containing complicated cysts showed high signal intensity on T1-weighted images, whereas some foci in those areas showed low signal intensity on short tau inversion recovery images. The mean minimum signal intensity ratios (SIRmin) of Warthin tumor on short tau inversion recovery (0.29 +/- 0.22 SD) (P < .01) and T2-weighted images (0.28 +/- 0.09) (P < .05) were significantly lower than those of malignant parotid tumors (0.53 +/- 0.19, 0.48 +/- 0.19). The average washout ratio of Warthin tumors (44.0 +/- 20.4%) was higher than that of malignant parotid tumors (11.9 +/- 11.6%). The mean apparent diffusion coefficient of Warthin tumors (0.96 +/- 0.13 x 10(-3)mm2/s) was significantly lower (P < .01) than that of malignant tumors (1.19 +/- 0.19 x 10(-3)mm2/s). CONCLUSION: Detecting hypointense areas of short tau inversion recovery and T2-weighted images or low apparent diffusion coefficient values on diffusion-weighted images was useful for predicting whether salivary gland tumors were Warthin tumors. The findings of the dynamic contrast-enhanced study also were useful.     

Soft-tissue tumors of the foot: value of MR imaging for specific diagnosis

We reviewed MR imaging findings in 14 patients with primary soft-tissue tumors of the foot and compared them with surgical and pathologic findings to determine the value of MR imaging in anatomic localization, delineation, and characterization of such lesions. Nine tumors (64%) were benign, and five (36%) were malignant. The anatomic location (compartment, space, relation to specific tendon) and extent of all tumors were accurately shown by MR imaging. Twelve tumors (86%) were correctly characterized as benign or malignant. Eight (89%) of nine benign lesions showed distinctive MR imaging features that correctly suggested a specific diagnosis. These included hemangioma (high T2-weighted intensity and internal septa), ganglion cyst (homogeneous, high T2-weighted weighted intensity and peritendinous location), plantar fibromatosis (nodularity of plantar aponeurosis with low intensity on all sequences), and pigmented villonodular synovitis (low T2-weighted intensity and lower intensity rim). Aggressive fibromatosis (one case) could not be characterized. Four (80%) of five malignant neoplasms had MR imaging findings suggesting soft-tissue sarcoma. Two synovial sarcomas were inhomogeneous and showed extensive peritendinous growth. Two clear cell sarcomas arose at the origin of the plantar aponeurosis and infiltrated adjacent muscle. A small clear cell sarcoma could not be characterized as benign or malignant. MR imaging of the foot is accurate in showing the extent of soft-tissue tumors, which is helpful for surgical planning. Determination of their specific anatomic location may help characterize some tumors. Although our series is small, it appears that MR imaging often suggests a specific diagnosis in certain benign soft-tissue tumors of the foot and may often correctly distinguish benign from malignant tumors.     

MR of the submandibular gland: normal and pathologic states.

PURPOSETo evaluate the MR appearance of normal and pathologic states of the submandibular gland.METHODSMR images of 22 healthy subjects and 21 patients with histopathologically confirmed disorders of the submandibular gland (five pleomorphic adenomas, two hemangiomas, two malignant lymphomas, one adenoid cystic carcinoma, one squamous cell carcinoma, and 10 cases of sialadenitis) were reviewed.RESULTSAll normal submandibular glands showed higher signal intensity than surrounding muscle but lower intensity than fat on T1-weighted and T2-weighted images. Postcontrast images showed moderate enhancement of the gland. All the tumors had lower signal intensity than the normal submandibular gland on T1-weighted images and had intermediate to high (n = 8) or high (n = 3) signal intensity relative to the normal submandibular gland on T2-weighted images. Six of seven benign tumors were well defined, and three of four malignant tumors were poorly defined. In all cases of sialadenitis, the submandibular gland showed diffusely different signal intensities from the normal gland on both T1-weighted and T2-weighted images. Eight cases of chronic sialadenitis showed lower T2-weighted signal intensities than the normal gland, and this can be explained histopathologically by marked fibrosis and cellular infiltration.CONCLUSIONSMR imaging can show the presence, extent, margins, and signal intensity changes of pathologic conditions of the submandibular gland.     

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.     

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.     

下肢神经源性肿瘤的MRI表现

目的 评估下肢神经源性肿瘤的MR表现。方法 回顾性分析5例经病理证实的下肢神经源性肿瘤的MR表现，其中4例为神经鞘瘤(3例良性，1例恶性)，1例为恶性神经纤维瘤；肿瘤分别位于小腿(2例)、腘区(1例)、大腿(1例)和股区(1例)。5例均行常规MR扫描，应用T1、T2加权序列作轴面、冠状面和矢状面扫描，2例良性神经鞘瘤应用T1WSE作增强扫描。结果 在T1WI2例良性神经鞘瘤呈等信号强度，1例良性神经鞘瘤、1例恶性神经鞘瘤和1例恶性神经纤维瘤呈不均质的低一中等信号强度。在T2WI5例肿瘤均呈不均质高信号。2例神经鞘瘤可见靶征，表现为瘤体中央为低信号区，其周围为高信号区，于T2WI显示清楚。结论 MRI有利于明确肿瘤的位置和范围，以及外科治疗计划的制定。靶征对周围神经源性肿瘤的诊断是1种有价值的征象。     

Breast lesions: evaluation with dynamic contrast-enhanced T1-weighted MR imaging and with T2*-weighted first-pass perfusion MR imaging

PURPOSE: To evaluate the diagnostic value of an imaging protocol that combines dynamic contrast-enhanced T1-weighted magnetic resonance (MR) imaging and T2*-weighted first-pass perfusion imaging in patients with breast tumors and to determine if T2*-weighted imaging can provide additional diagnostic information to that obtained with T1-weighted imaging. MATERIALS AND METHODS: One hundred thirty patients with breast tumors underwent MR imaging with dynamic contrast-enhanced T1-weighted imaging of the entire breast, which was followed immediately with single-section, T2*-weighted imaging of the tumor. RESULTS: With T2*-weighted perfusion imaging, 57 of 72 carcinomas but only four of 58 benign lesions had a signal intensity loss of 20% or more during the first pass, for a sensitivity of 79% and a specificity of 93%. With dynamic contrast-enhanced T1-weighted imaging, 64 carcinomas and 19 benign lesions showed a signal intensity increase of 90% or more in the first image obtained after the administration of contrast material, for a sensitivity of 89% and a specificity of 67%. CONCLUSION: T2*-weighted first-pass perfusion imaging can help differentiate between benign and malignant breast lesions with a high level of specificity. The combination of T1-weighted and T2*-weighted imaging is feasible in a single patient examination and may improve breast MR imaging.     

磁共振信号强度在胸膜疾病中的诊断意义

目的评价磁共振信号强度在胸膜疾病中的诊断价值.方法48例不同胸膜疾病病人在Philips0.5T扫描仪下行MR检查.成像常规为T1WI、T2WI快速自旋回波扫描,所有病例均在病理证实结合临床资料下得出恶性或良性胸膜疾病的诊断.恶性疾病包括胸膜间皮瘤(n=10)、胸膜转移瘤(n=18),良性疾病包括结核性胸膜炎(n=9)、胸膜肥厚(n=7)、纤维胸(n=1)、脓胸(n=2)和胸膜炎性假瘤(n=1).将各种胸膜疾病T1WI、T2WI上绝对信号强度(ASI),病灶信号与肌肉信号的对比噪声比(CNR),信号强度比(SIR)分别进行测量或计算,判断它们在良、恶性胸膜疾病之间,胸膜间皮瘤与胸膜转移瘤之间是否存在差别.结果ASI在良、恶性胸膜疾病之间,胸膜间皮瘤与转移瘤之间均无显著差异,CNR在良、恶性胸膜疾病之间于T2WI上有差别(P＜0.01),而SIR在良、恶性胸膜疾病之间于T1WI、T2WI上均有极显著差异(P＜0.001),同时,还在胸膜间皮瘤与转移瘤之间于T2WI上存在差别(P＜0.05).结论磁共振信号强度在胸膜疾病鉴别诊断中有重要意义,其中SIR最具有诊断价值.MR信号强度在T2WI上比T1WI上更具有区分不同胸膜疾病的能力.     

Diagnostic value of dynamic magnetic resonance imaging for salivary gland diseases: a preliminary study

OBJECTIVES: To determine the diagnostic value of dynamic MR imaging for the differentiation between benign tumours, malignant tumours, and inflammatory lesions in the major salivary glands. METHODS: T1- and T2-weighted spin-echo and dynamic gadolinium-enhanced T1-weighted spin-echo imaging sequences were performed in 27 patients (28 salivary gland lesions). The enhancement curve patterns and tumour margins on dynamic MR imaging were analysed. RESULTS: All pleomorphic adenomas showed a continuous gradual or rapid increase in the enhancement pattern, whereas other benign tumours had a rapid or gradual enhancement-attenuation pattern. Malignant tumours generally showed a gradual enhancement-attenuation pattern. Inflammatory lesions showed a rapid or gradual enhancement-attenuation pattern. A well-defined margin was observed in all 13 (100%) benign tumours and three of six (50%) malignant tumours. CONCLUSIONS: Our study suggests that dynamic curve patterns and tumour margin appearance may help to differentiate between benign tumours, malignant tumours and inflammatory lesions.     

Soft tissue masses with “cyst-like” appearance on MR imaging: distinction of benign and malignant lesions

The purpose of this study was to assess the reliability of MR imaging features in distinguishing between benign and malignant soft tissue masses that have a “cyst-like” appearance (hypointense to muscle on T1-weighted and hyperintense on T2-weighted or fluid-sensitive MR sequences). MR imaging features of 40 patients with histologically proven soft tissue masses (27 benign and 13 malignant lesions) that were hypointense to muscle on T1-weighted and hyperintense on T2-weighted or fluid-sensitive MR sequences were analysed to see if a distinction could be made between benign and malignant lesions. There were 23 females and 17 males (mean age, 56 years; age range, 23–82 years). MR imaging features analysed for statistical significance included lesion size, lesion homogeneity, presence of lobulation, depth in relation to fascia and border definition. Clinical assessment included the age and sex of the patient and location of the lesion. Statistically significant MR imaging features favouring a diagnosis of a malignant lesion included larger average dimension of the mass (P≤0.004), larger greatest dimension of the mass (P≤0.028) and heterogeneity of the lesion on T1-weighted sequences (P=0.017). The most statistically significant predictor of malignancy was the larger average dimension of the mass.     

Does the presence of focal normal marrow fat signal within a tumor on MRI exclude malignancy? An analysis of 184 histologically proven tumors of the pelvic and appendicular skeleton

OBJECTIVE: The aim of this study was to determine if the presence of focal normal bone marrow fat signal within a tumor on magnetic resonance imaging excludes malignancy. MATERIALS AND METHODS: One hundred eighty-four histologically proven tumors with available magnetic resonance imaging (MRI) of the appendicular skeleton and pelvis from 184 patients were collected and reviewed at two separate institutions. There were 111 malignant and 73 benign tumors. Two radiologists at each institution, blinded to the diagnosis, reviewed the MRIs independently and reported the presence or absence of normal marrow fat signal within the tumor based upon T1-weighted imaging without fat suppression and T2-weighted imaging with fat suppression and/or short inversion-time inversion recovery (STIR). Discrepancies were then reviewed in consensus to determine the presence or absence of focal normal marrow signal. For each institution, a Fisher's exact test was used to compare the frequency of focal normal marrow fat signal in benign and malignant tumors. This comparison was performed for each reader, as well as for the consensus reading at each site. Positive and negative predictive values were also calculated for each reader, as well as the consensus reading at each site. Fisher's exact test was also used to compare the frequency of intratumoral fat in benign and malignant lesions for the pooled sample. Bayes theorem was used to calculate the positive and negative predictive values for the pooled consensus data. Ninety-five percent confidence intervals were constructed for the pooled estimates using a bootstrapping algorithm. RESULTS: There was good interobserver reliability of 95.3% and 96.7% at sites 1 and 2, respectively. There were three discrepancies (one malignant and two benign) at site 1 and four discrepancies (two malignant and two benign) at site 2. Reader consensus at site 1 identified normal marrow fat signal within 1 of 50 (2.0%) malignant and three of 14 (21.4%) benign tumors. Findings were statistically significant with a p value of 0.030. The positive predictive value (PPV) and negative predictive value (NPV) at site 1 was 81.7% and 75.0%, respectively. Reader consensus at site 2 identified normal marrow fat signal within three of 61 (4.9%) malignant and 14 of 59 (23.7%) benign tumors. Findings were statistically significant with a calculated p value of 0.004. The PPV and NPV at site 1 was 56.3% and 82.4%, respectively. For the pooled consensus, the frequency of intratumoral fat in benign lesions (17/73, 23.3%) is significantly greater than the frequency in malignant lesions (4/111, 3.6%), p < 0.001. CONCLUSION: The presence of focal normal marrow signal within a tumor is highly suggestive of a benign tumor.     

Improved detection and delineation of head and neck lesions with fat suppression spin-echo MR imaging.

To compare conventional and fat suppression MR imaging in their ability to detect head and neck lesions, we prospectively studied 17 patients with head and neck tumors and one normal volunteer. Five patients had benign tumors (one mixed cell tumor, one hemangioma, one lipoma, and two plexiform neurofibromas), 10 had malignant tumors (six squamous cell carcinomas, two minor salivary gland carcinomas, one lymphoma, and one malignant fibrous histiocytoma), and two had nonspecific lymphadenopathy. All subjects were studied with standard spin-echo T1- and T2-weighted images (T2-weighted imaging was done with and without fat suppression technique). In addition, T1-weighted images with contrast enhancement and fat suppression were obtained in nine patients. A four-point grading system was used for comparison of the conventional and fat suppression images. Grades ranged from 0 (unsatisfactory, the lesion cannot be seen) to 3 (excellent, the lesion and its margins can be seen clearly with sharp contrast from surrounding normal tissue). We found that postcontrast fat suppression T1-weighted images and fat suppression T2-weighted images were most useful; these sequences obtained an average score close to grade 3 (2.77 and 2.85, respectively). On the other hand, the conventional T2-weighted images had an average score of about 2 (1.82) and the conventional T1-weighted image had a score of about 1 (1.33). Fat suppression T2-weighted sequences generally were superior in cases of lymphadenopathies. Postcontrast T1-weighted images were most useful in a case of plexiform neurofibroma, owing to their fibrous component and lower proton density.(ABSTRACT TRUNCATED AT 250 WORDS)     

MR lymphangiography using ultrasmall superparamagnetic iron oxide in patients with primary abdominal and pelvic malignancies: radiographic-pathologic correlation

OBJECTIVE: The purpose of this study was to administer ultrasmall superparamagnetic iron oxide (USPIO) and compare changes in signal intensity of lymph nodes in patients with primary abdominal and pelvic malignancies. Also, we correlated radiographic with pathologic findings. SUBJECTS AND METHODS: Nineteen patients with proven primary abdominal or pelvic cancer (prostatic [n = 10]; colonic [n = 5]; endometrial [n = 1]; Merkel cell tumor [n = 1]; lymphoma [n = 1]; seminoma [n = 1]) were enrolled as part of our phase II and phase III clinical trials. In these patients, 49 lymph nodes (mean size, 1.4 cm) revealed on CT or MR imaging were evaluated on T1-weighted spin-echo, T2-weighted fast spin-echo, and T2*-weighted gradient-echo MR imaging at 1.5 T 24-36 hr after IV administration of USPIO. Quantitative analyses used measurements of unenhanced and enhanced region-of-interest values in lymph nodes. Qualitative assessment used subjective evaluation and classification of changes in signal intensity. All patients underwent lymph node biopsy or surgical dissection followed by histopathologic correlation. RESULTS: Of the 49 lymph nodes that were evaluated, 20 were benign and 29 were malignant. A decrease in nodal signal intensity on enhanced T2-weighted and T2*-weighted gradient-echo images was seen in 20 benign lymph nodes and two malignant lymph nodes. No appreciable signal change was noted in 27 of the 29 malignant lymph nodes. The mean signal intensity on fast spin-echo T2-weighted images for benign lymph nodes changed from 186.48 (unenhanced) to 73.66 (enhanced). Conversely, mean signal intensity for malignant lymph nodes was relatively unchanged from 191.17 (unenhanced) to 183.18 (enhanced). CONCLUSION: USPIO appears to be a useful MR contrast agent for characterizing benign and malignant lymph nodes based on the enhancement criteria evaluated in our study.     

Adrenal masses: characterization with T1-weighted MR imaging

The ability of a T1-weighted spin-echo magnetic resonance (MR) sequence to allow differentiation of benign from malignant adrenal masses at 0.5 T was investigated in 28 patients with 35 adrenal masses. All nine lesions with an adrenal mass-liver signal intensity ratio of 0.71 or less were metastases, and all 15 with a ratio of 0.78 or more were adenomas. Eleven masses (31%)--including six adenomas, three metastases, a pheochromocytoma, and a neuroblastoma--had ratios between these values. Nine of ten masses with adrenal mass-fat intensity ratios of 0.35 or less were metastases, and all 12 with ratios of 0.42 or more were benign. Eleven masses (31%), four malignant and one benign, had ratios between these values. The ratios for two masses could not be calculated due to lack of fat. The specificity of T1-weighted MR imaging in differentiating benign from malignant adrenal masses appears similar to that reported for T2-weighted imaging. However, significant overlap occurred, as has also been reported for T2-weighted imaging. While both imaging sequences may help distinguish benign from malignant adrenal masses in some cases, biopsy is still necessary when an accurate histologic diagnosis is essential.     

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.