Soft-tissue masses: histologic basis for decreased signal (short T2) on T2-weighted MR images

Most soft-tissue masses and tumors of various etiologies and histologies have high signal intensity on T2-weighted pulse sequences (long T2). Of 47 soft-tissue masses, seven had a low signal (short T2) on T2-weighted pulse sequences. All seven masses were tumors, and histologic review showed that their composition differed from that of the other 40 lesions with a long T2 in that the seven masses were relatively acellular and had more collagen. The tumors with a short T2 included one malignant and six benign soft-tissue tumors. Malignant fibrous histiocytoma and aggressive fibromatosis showed paradoxical signal intensities in that they showed both long and short T2. All of the tumors with low signal intensity on T2-weighted images had significant fibrous elements and marked hypocellularity. This study suggests that the less commonly encountered short T2 may be seen in both benign and malignant soft-tissue lesions. A part of the explanation for the low signal on T2-weighted sequences appears to be the relative acellularity and abundant collagen of these tumors in comparison with those that have the same histologic diagnoses but show a high signal. The histologic composition of the tumor rather than the histologic diagnosis appears to influence the MR signal on T2-weighted sequences.     

Soft-tissue masses of the locomotor system: comparison of MR imaging with CT

Magnetic resonance (MR) images and computed tomographic (CT) scans of histologically characterized soft-tissue masses of the locomotor system in 35 patients were compared for image contrast, demonstration of bone destruction, and display of extent and anatomic relationships of the masses. Subjective criteria for predicting malignancy were tested. T1 measurements were made in a few cases. Intensities of masses relative to those of fat and muscle in spin-echo T1-weighted and highly T2-weighted images were evaluated for correlation with tissue type. Subjective value of using coronal and sagittal images was assessed. Because of its superior inherent image contrast and its ability to provide direct sagittal and coronal images, MR was better than CT in demonstrating size and extent of most tumors and their relationships to vascular and nonvascular structures. However, bone destruction was more difficult to see with MR. Except for fatty tumors, MR was not helpful in identifying tissue type. Subjective criteria were of limited value in distinguishing benign from malignant lesions. Moreover, there is currently no credible evidence that T1 or T2 measurements are helpful in this regard. Study results suggest that MR is superior to CT in evaluating soft-tissue masses of the locomotor system. If an MR examination is performed, CT may not be necessary in certain cases unless bone involvement is suspected.     

Cholesterol granulomas of the middle ear cavities: MR imaging

Symptomatic cholesterol granuloma developed in the middle ear cavities in three cases. At computed tomography (CT) after the administration of contrast material, the granulomas appeared as nonspecific, nonenhanced soft-tissue masses with variable bone erosion. These features are indistinguishable from those of other similar clinical entities, especially cholesteatoma, paraganglioma, and endaural brain hernia. At magnetic resonance (MR) imaging, cholesterol granulomas had a more characteristic appearance. In two cases, the granulomas were depicted as areas of high signal intensity with both T1- and T2-weighted sequences. In the third case, an expansile mastoid cholesterol cyst exhibited medium signal intensity on T1-weighted images, with only a small hyperintense area and a hypointense area located in the cystic wall. Correlations between CT, MR, and microscopic findings show that MR imaging is far superior to CT in tumoral characterization, which is crucial for planning surgical approaches. MR imaging has limitations, however, particularly its inability to depict subtle bone abnormalities.     

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.     

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.     

Comparative evaluation of multidetector CT and MR imaging in the differentiation of adnexal masses

The purpose was to compare the accuracy of multidetector CT (MDCT) on a 16-row CT scanner and magnetic resonance (MR) imaging in the characterization of ovarian masses. Preoperative CT examination of the abdomen and MR imaging of the pelvis was performed in 67 women, with clinically or sonographically detected adnexal masses. The CT examinations were performed on a 16-row CT scanner, and the protocol included scanning of the abdomen during the portal phase, using a detector collimation of 16 × 0.75 mm and a pitch of 1.2. We used a 1.5-T magnet unit to perform T1, T2 and fat-suppressed T1-weighted sequences, before and after intravenous administration of gadolinium chelate compounds. The accuracy of multidetector CT and MR imaging in the differentiation between benign and malignant ovarian masses was evaluated, using histopathologic results as the standard of reference. The sensitivity, specificity and accuracy of MDCT in the characterization of ovarian masses were 90.5%, 93.7% and 92.9%, respectively, and that of MR imaging 95.2%, 98.4% and 97.6%, respectively. Although MRI performed slightly better, this did not reach statistical significance. In conclusion, both MDCT on a 16-row CT scanner and MR imaging demonstrated satisfactory results in the characterization of ovarian masses.     

Detection of hepatic masses in patients with carcinoma: comparative sensitivities of sonography, CT, and MR imaging

To evaluate the sensitivity of sonography, CT, and MR imaging in the detection of hepatic masses in carcinoma patients, we conducted a prospective study of 75 consecutive patients with gastrointestinal tumors who were admitted for surgical resection of the primary tumor. Sonography was performed with convex transducers of 3.5 and 5.0 MHz. Three noninvasive CT techniques were used: unenhanced CT scans, the incremental bolus dynamic scanning technique, and delayed scanning 4-6 hr after bolus injection of 60 g of iodine. MR images (1.5 T) were acquired as presaturated T1- and T2-weighted spin-echo sequences and as breath-holding fast low-angle shot (FLASH) 60 degrees and FLASH 15 degrees sequences. As it is difficult to distinguish benign from malignant masses solely on the basis of morphologic criteria, the techniques for each imaging method were designed to detect and not to characterize hepatic lesions. Each examination was interpreted blindly, and the results were compared with surgical findings, intraoperative sonography, and biopsy of the liver as the gold standard. All focal hepatic masses verified at surgery, malignant or benign, were included in the analysis. Sixty-five (68%) of 95 focal hepatic masses were detected by CT, 60 lesions (63%) by MR, and 50 lesions (53%) by sonography. Although lesions 1-2 cm were shown almost equally well by CT and MR (74% and 77%, respectively), the detection rate of smaller lesions (less than 1.0 cm) decreased more drastically with MR (31%) than with CT (49%). Sonography had a sensitivity of only 20% with the smaller lesions. All imaging techniques had a sensitivity of 100% for focal hepatic masses larger than 2.0 cm. Our results show that CT has a higher overall sensitivity (68%) than MR and sonography for the detection of focal hepatic masses. When the results of the three procedures are combined, the overall sensitivity is 77%. This is unsatisfactorily low, as CT and MR have a size threshold of about 1.0 cm and are relatively unreliable for the detection of smaller 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.     

Hepatic lesion detection and characterization: value of nonenhanced MR imaging, superparamagnetic iron oxide-enhanced MR imaging, and spiral CT-ROC analysis

PURPOSE: To determine the accuracy for detection and characterization of focal hepatic lesions of nonenhanced, superparamagnetic iron oxide (SPIO)-enhanced, or a combination of nonenhanced and SPIO-enhanced MR imaging and contrast-enhanced spiral computed tomography (CT). MATERIALS AND METHODS: Spiral CT and T2-weighted SPIO-enhanced (ferucarbotran-enhanced) MR imaging were performed in 35 patients within 2 weeks before surgery for malignant hepatic lesions. Only malignant lesions with histopathologic proof were considered. A total of 875 images with and 800 images without focal lesions were presented to five readers, who were asked to assess the presence and characterization of lesions by using a five-point confidence scale. Receiver operating characteristic analysis was performed. RESULTS: Nonenhanced and SPIO-enhanced images together and SPIO-enhanced images alone yielded the best performance for lesion detection. No differences were found among all imaging techniques with regard to lesion characterization (benign vs malignant). The combined approach resulted in larger area under the ROC curve (A(z) = 0.9062) and accuracy (85.3%) (P < 0.02), as compared with SPIO-enhanced MR imaging (A(z) = 0.8667; accuracy, 73.1%). CONCLUSION: SPIO-enhanced T2-weighted MR imaging was more accurate than nonenhanced T1-weighted and T2-weighted MR imaging and contrast-enhanced spiral CT for the detection of focal hepatic lesions. The combined analysis of nonenhanced and SPIO-enhanced images was more accurate in the characterization of focal hepatic lesions than was review of SPIO-enhanced images alone.     

MR imaging differentiation of soft-tissue hemangiomas from malignant soft-tissue masses

OBJECTIVE: The purpose of this study was to determine whether MR imaging features can reliably distinguish hemangiomas from malignant soft-tissue masses. MATERIALS AND METHODS: We retrospectively reviewed MR imaging studies of 22 patients with soft-tissue hemangiomas and 22 patients with malignant soft-tissue masses. Images were reviewed and agreement reached by a consensus interpretation of two observers and by an independent observer. Masses were evaluated for signal intensity on T1- and T2-weighted images, for enhancement with gadolinium administration, and for morphology (lobulation, septation, central low-intensity dots). Lesion T2 signal and lesion enhancement with gadolinium administration were also objectively measured using regions of interest and comparison with skeletal muscle. RESULTS: Signal intensity on T1-weighted imaging of hemangiomas and malignant soft-tissue masses was similar. Subjective analysis showed greater T2 signal and gadolinium enhancement in hemangiomas; however, the differences were not statistically significant on objective analysis. Lobulation, septation, and central low-signal-intensity dots were all more common in hemangiomas, with statistical significance achieved; the combination of all three findings was specific for hemangioma. CONCLUSION: Although no single MR imaging feature was diagnostic in this study, analysis of lesion morphology, signal intensity, and enhancement with gadolinium allowed MR imaging differentiation of hemangiomas from malignant soft-tissue masses.     

MRI对软组织肿块的诊断价值

目的：探讨ＭＲＩ鉴别软组织肿块良、恶性的价值。方法：ＭＲＩ检查６７例软组织肿块,其中２５例肿块应用ＳＴＩＲ成像,４７例肿块Ｇｄ－ＤＴＰＡ增强造影。结果：６７例软组织肿块,良性５２例,恶性１５例。根据ＭＲＩ影像特征,１１例（２１．２％）良性肿块和１例（６．７％）恶性肿块正确诊断。当ＭＲＩ影像特征结合临床资料后,良性肿块定性准确率９４．２％,恶性肿块定性准确率８０％。结论：仅根据ＭＲＩ影像特征,大多数软组织肿块的良、恶性鉴别是不可靠的,当ＭＲＩ影像特征和临床资料结合后,大多数软组织肿块的良、恶性鉴别是可能的。     

CT and MR imaging of benign primary cardiac neoplasms with echocardiographic correlation.

Benign primary cardiac neoplasms are rare but may cause significant morbidity and mortality. However, they are usually treatable and can often be diagnosed with echocardiography, computed tomography (CT), or magnetic resonance (MR) imaging. Myxomas typically arise from the interatrial septum from a narrow base of attachment. Fibroelastomas are easily detected at echocardiography as small, mobile masses attached to valves by a short pedicle. Cardiac fibromas manifest as a large, noncontractile, solid mass in a ventricular wall at echocardiography and as a homogeneous mass with soft-tissue attenuation at CT. They are usually homogeneous and hypointense on T2-weighted MR images and isointense relative to muscle on T1-weighted images. Paragangliomas usually appear as large, echogenic left atrial masses at echocardiography and as circumscribed, heterogeneous masses with low attenuation at CT. These tumors are usually markedly hyperintense on T2-weighted MR images and iso- or hypointense relative to myocardium on T1-weighted images. Cardiac lipomas manifest at CT as homogeneous, low-attenuation masses in a cardiac chamber or in the pericardial space and demonstrate homogeneous increased signal intensity that decreases with fat-saturated sequences at T1-weighted MR imaging. Cardiac lymphangiomas manifest as cystic masses at echocardiography and typically demonstrate increased signal intensity at T1- and T2-weighted MR imaging. Familiarity with these imaging features and with the relative effectiveness of these modalities is essential for prompt diagnosis and effective treatment.     

MR imaging of renal masses interpreted on CT to be suspicious

OBJECTIVE: Prior studies have shown that renal MR contrast enhancement improves the efficacy of mass and proximal vascular evaluation. This study assessed the usefulness of different sequences for characterization of masses that appeared suspicious on CT and for prediction of their potential for malignancy. SUBJECTS AND METHODS: In a prospective manner 32 patients (age range, 26-78 years: average age, 54 years), each with at least one suspicious mass on CT, were examined with MR imaging. The following sequences were performed: conventional spin-echo with and without fat saturation, fast spin-echo, and dynamic gadopentetate dimeglumine-enhanced infusion using a 1.5-T superconducting magnet. Results were analyzed and compared with pathologic results after resection. RESULTS: A total of 65 renal masses of average size 2.6 cm (range, 1-10 cm) were detected with dynamic MR imaging. Seventeen of the 65 masses were malignant. Of the 17 malignant masses, three did not enhance on dynamic MR imaging (because of hemorrhage). Sixteen of the 17 malignant masses were heterogeneous on T2-weighted images. Three enhancing masses contained fat and all were angiomyolipomas. Thirty-five of the 65 masses (four with hemorrhage) did not show enhancement, all of which were homogeneous on T2-weighted images and were proven to be cysts. Five masses resulted from infections and had heterogeneous T2 appearance. The remaining masses were three hematomas with hemorrhage, one column of Bertin, and one aneurysm. CONCLUSION: Renal masses that are interpreted as suspicious on CT may lack MR enhancement because of hemorrhage effects; heterogeneity of their T2 appearance is thus critical in differentiating malignancy from benign disease. Odds-ratio calculations give an adjusted estimate of a 3.36-fold increase (95% confidence interval, 1.8-6.27) in the likelihood of malignancy when masses are heterogeneous on T2-weighted images and a 29-fold increase (95% confidence interval, 3.67-241.8) for predicting malignancy when enhancement is present.     

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.     

Tumour and tumour-like conditions of the soft tissue: magnetic resonance imaging features differentiating benign from malignant masses.

49 primary soft-tissue masses were studied by magnetic resonance imaging (MRI) in an effort to differentiate benign from malignant lesions. There were 24 benign and 25 malignant tumours. Images were evaluated for the presence of low-signal septation, changes in pattern of homogeneity, signal intensity, and margin definition and shape. 20 of the 25 malignant tumours (80%) demonstrated low-signal septation, and two of the 24 benign tumours (8%) also demonstrated this feature. Malignant tumours tended to change pattern from being homogeneous on T1-weighted images to being heterogeneous on T2-weighted images (72%). Benign tumours maintained their pattern on both sequences (67%). Only three of the 24 benign tumours (12.5%) changed from being homogeneous to heterogeneous. Our findings suggest that tumours which change pattern, from homogeneous on T1-weighted images to heterogeneous on T2-weighted images, and tumours which have low-signal septations are likely to be malignant. Moreover benign lesions tend to have well defined margins, and some benign masses have characteristic appearances that aid in their differentiation from malignant processes.     

Comparison between high-field-strength MR imaging and CT for screening of hepatic metastases: a receiver operating characteristic analysis.

The diagnostic performance of high-field-strength magnetic resonance (MR) imaging (1.5 T) for detection of liver metastases was compared with that of computed tomography (CT). All patients (n = 52) underwent preoperative screening for metastases by means of MR imaging with T1-weighted, proton-density-weighted, and T2-weighted pulse sequences and CT scanning with unenhanced, incremental dynamic bolus-enhanced, and delayed contrast medium-enhanced techniques. Diagnostic performance was evaluated by means of receiver operating characteristic analysis in which 800 images (400 with and 400 without lesions) and five readers (4,000 observations) were used; images were obtained from patients (n = 39) in whom the same anatomic levels were available for all MR imaging and CT studies. Direct comparison between the best MR imaging technique (T2-weighted spin-echo imaging [repetition time, 2,000 msec; echo time, 70 msec]) and the best CT technique (incremental dynamic bolus CT) showed a strong trend of superiority of T2-weighted MR imaging over incremental dynamic bolus CT. No highly statistically significant difference (P greater than or equal to .01), however, was found between these two techniques.     

Tophaceous gout of the spine: MR imaging features

AIM: To define the magnetic resonance (MR) imaging features of tophaceous gout of the spine. MATERIALS AND METHODS: We present the MR imaging examinations of 4 patients with spinal tophaceous gout. Spin-echo T1-weighted and fast spin-echo T2-weighted images were obtained for all patients, and 2 patients had gadolinium-enhanced MR imaging studies. Corresponding computed tomography (CT) was performed in one patient. All images were evaluated for the characteristics of the gouty tophi. RESULTS: The gouty tophi were located at the lower thoracic (n=1) and lumbar (n=3) levels. All tophi yielded homogeneous intermediate to low signal on T1-weighted images and variable signal intensity on T2-weighted images, comprising small foci of very low signal intensity on all sequences. Gadolinium-enhanced MR imaging studies revealed homogeneous enhancement or heterogeneous peripheral enhancement. Diffuse stippled calcifications were found in the tophi on CT images. Periarticular tophi with juxtaarticular bony erosions around facet joints occurred in 3 patients. CONCLUSION: Spinal tophaceous gout should be considered in the differential diagnosis when periarticular deposits contain very low signal foci on all MR imaging sequences.     

Adnexal masses: MR imaging observations at 1.5 T, with US and CT correlation

To assess the role of 1.5-T magnetic resonance (MR) imaging in evaluation of the adnexa, 43 consecutive examinations that revealed 61 adnexal masses were retrospectively reviewed. T1- and T2-weighted images in coronal, axial, and/or sagittal planes were included. Available ultrasound (US) (n = 30) and/or computed tomographic (CT) (n = 9) scans were then correlated with the MR images. On T2-weighted images at least part of all adnexal masses was of higher signal intensity than surrounding muscle and adipose tissue, and therefore the adnexal masses were best seen with these sequences. T1-weighted imaging improved tissue characterization by revealing signal characteristics of fat in teratomas and characteristics of blood in endometriomas or hemorrhagic cysts, pelvic inflammatory disease, ovarian carcinomas, serous cystadenomas, and teratomas. MR imaging provided additional information or increased diagnostic confidence in 25 of 30 patients who underwent US or CT. MR imaging is a promising problem-solving modality after US in the study of adnexal abnormalities.     

Ovarian lesions: detection and characterization with gadolinium-enhanced MR imaging at 1.5 T

Magnetic resonance (MR) imaging for detection and characterization of ovarian masses was assessed in 33 patients with a total of 60 lesions. Lesions were characterized prospectively as benign or malignant by using T2-weighted MR images and unenhanced and gadolinium-enhanced T1-weighted MR images. MR imaging findings were compared with results of surgical laparotomy performed for staging of lesions. When malignancy was suspected, staging with MR imaging was performed. MR imaging demonstrated 57 of 60 (95%) surgically proved ovarian masses (34 of 36 were benign, 23 of 24 were malignant). Five significant primary criteria and four ancillary criteria for malignancy were established. For all MR pulse sequences combined, characterization of either type of lesion was correct in 84% of cases (48 of 57) when the five primary criteria were used and 95% (54 of 57) were correct when the four ancillary criteria were added. With gadolinium-enhanced images, correct characterization of malignant lesions increased from 56% to 78% with use of the five primary criteria and from 83% to 100% with use of both sets of criteria. Malignancies were correctly staged with MR imaging in 12 of 16 patients. Staging accuracy was 63% with unenhanced images and 75% with the addition of enhanced images.     

CT and MR imaging of mediastinal hemangiomas

We describe the CT findings in two cases of mediastinal hemangioma. In one, contrast enhanced CT demonstrated peripheral puddles of contrast medium within the mass, similar to the findings seen in cavernous hemangiomas of the liver. In the other case magnetic resonance (MR) was performed; the mass had an intraspinal component and was hypointense on T1-weighted sequences and hyperintense on T2-weighted sequences; imaging features were similar to those of neurogenic tumors. Although they have a nonspecific appearance on MR, these tumors may demonstrate characteristic contrast enhancement features on CT. Hence, hemangiomas of the mediastinum, although rare, should be included in the differential diagnosis of enhancing mediastinal masses.