MR imaging of common and uncommon large pelvic masses.

Magnetic resonance (MR) imaging is often used in the detection and staging of large pelvic masses. Many large masses in the female pelvis arise from the reproductive organs (eg, uterus, cervix, ovaries, fallopian tubes). In addition, these masses may arise from the gastrointestinal system, urinary system, adjacent soft tissues, peritoneum, or retroperitoneum or from metastases. The majority of large masses in the female pelvis represent such commonly encountered entities as uterine fibroid tumor, dermoid tumor, ovarian cyst, and ovarian cancer. However, uncommon pelvic masses such as mesothelioma, adenocarcinoma, carcinosarcoma, leiomyosarcoma, and desmoid tumor may also be seen. Thus, the differential diagnosis for female pelvic masses is extensive. However, the site of origin, MR imaging characteristics, and clinical history may all help narrow the differential diagnosis. Although with large tumors it may not always be possible to determine the site of origin or distinguish between various tumors at radiology, familiarity with the clinicopathologic and MR imaging features of common and uncommon pelvic masses is important for diagnosis and treatment.     

Evaluation of adrenal masses in oncologic patients: dynamic contrast-enhanced MR vs CT

The CT examinations, precontrast gradient echo MR images, and fast contrast enhanced dynamic MR studies were evaluated in 44 patients with 52 adrenal masses and known malignant disease of different origin. Morphologic features (size, shape, attenuation, contour, and enhancement) on CT scans, signal intensity on T2-weighted MR images, and patterns of enhancement on Gd-DTPA enhanced dynamic MR studies were analyzed in all patients. With dynamic contrast enhanced studies with prolonged imaging up to 15 min after Gd-DTPA, masses with moderate enhancement and complete washout after 10 min were considered as adenomas. Computed tomography and plain MR had a sensitivity of 0.71 and 0.96, a specificity of 0.75 and 0.88, and overall accuracy of 0.56 and 0.71, respectively. Simultaneous use of precontrast MR and dynamic contrast enhanced studies led to an accurate diagnosis in 88% (sensitivity = 1.0, specificity = 0.91) and thus should be considered in oncologic patients with undetermined adrenal masses.     

Detection of hepatic metastases: comparison of contrast-enhanced CT, unenhanced MR imaging, and iron oxide-enhanced MR imaging

Diagnostic accuracy of contrast-enhanced CT, unenhanced MR imaging, and MR images enhanced with superparamagnetic iron oxide was evaluated in 10 patients with histologically proved hepatic metastases. First, diagnostic performance of the imaging technique with respect to the ability of radiologists to recognize the presence or absence of a metastasis was measured by using receiver-operating-characteristic (ROC) analysis of single images. Second, the total number of lesions (N = 108) detected by "complete" CT and MR examinations was counted. Finally, lesion-liver contrast-to-noise ratios (CNR) were measured in all MR sequences. The area under the ROC curve was .67 +/- .03 for contrast-enhanced CT, .81 +/- .07 for the unenhanced SE 260/14 sequence, and .92 +/- .01 for the iron oxide-enhanced SE 1500/40 sequence. The enhanced SE 1500/40 sequence yielded significantly (p less than .005) greater accuracy than did contrast-enhanced CT. The same sequence detected significantly (p less than .05) more lesions than all other imaging techniques (19% more than the best unenhanced MR sequence and 36% more than contrast-enhanced CT). The enhanced SE 1500/40 sequence also yielded the highest CNR value (19.5 +/- 10.2) of all MR sequences. These results indicate that iron oxide-enhanced MR imaging is a superior imaging technique for the detection of hepatic lesions.     

Detection of non-palpable breast cancer in asymptomatic women by using unenhanced diffusion-weighted and T2-weighted MR imaging: comparison with mammography and dynamic contrast-enhanced MR imaging

Objective

To compare the detectability of non-palpable breast cancer in asymptomatic women by using mammography (MMG), dynamic contrast-enhanced MR imaging (DCE-MRI) and unenhanced MR imaging with combined diffusion-weighted and T2-weighted images (DWI?+?T2WI).

Methods

Forty-two lesions in 42 patients with non-palpable breast cancer in asymptomatic women were enrolled. For the reading test, we prepared a control including 13 normal and 8 benign cases. Each imaging set included biplane MMG, DCE-MRI and DWI?+?T2WI. Five readers were asked to rate the images on a scale of 0 to 100 for the likelihood of the presence of cancer and the BI-RADS category. Confidence level results were used to construct receiver operating characteristic analysis. Sensitivity and specificity were calculated for each technique.

Results

DWI?+?T2WI showed higher observer performances (area under the curve, AUC, 0.73) and sensitivity (50%) for the detection of non-palpable breast cancer than MMG alone (AUC 0.64; sensitivity 40%) but lower than those of DCE-MRI (AUC 0.93; sensitivity 86%). A combination of MMG and DWI?+?T2WI exhibited higher sensitivity (69%) compared with that of MMG alone (40%).

Conclusion

DWI?+?T2WI could be useful in screening breast cancer for patients who cannot receive contrast medium and could be used as a new screening technique for breast cancer.     

MR imaging of peripheral intracranial neoplasms: extraaxial vs intraaxial masses

In an effort to determine magnetic resonance (MR) features of peripheral brain tumors that allow accurate localization. 11 extraaxial neoplasms were compared with 11 peripheral intraaxial tumors. The MR findings most often seen in extraaxial lesions include interruption of bone, white matter buckling, widening of adjacent subarachnoid space or cistern, and medial displacement of pial arteries or veins. Invasion of the cortex without white matter buckling, as well as flattening and lateral displacement of the surface veins, was most often seen in intraaxial lesions. Neither simple contiguity to a bony or dural surface nor vasogenic edema is a reliable predictor of intra- vs extraaxial masses.     

Detection of residual or recurrent meningioma after surgery: value of enhanced vs unenhanced MR imaging.

The enhanced and unenhanced MR examinations obtained after surgery for meningioma in 38 patients were reviewed to determine the value of enhanced vs unenhanced MR imaging for the detection of residual or recurrent tumor. Enhanced images improved delineation of the extent of tumor in seven of 13 cases in which meningioma was identified on unenhanced images and allowed more definitive detection or exclusion of residual or recurrent meningioma in 18 of 21 cases with equivocal findings on unenhanced images. In addition, enhanced images were helpful for detecting small recurrences, identifying en plaque growth, and showing subtle progression on serial studies. Enhanced MR imaging also allowed detection of two morphologic patterns of dural enhancement adjacent to the surgical bed: (1) thin and smooth, which was seen in patients both with and without residual or recurrent tumor, and (2) thick and nodular, which was seen only in patients with findings indicative of, or at least suggestive of, residual or recurrent meningioma. Unenhanced images failed to detect, or poorly detected, these dural abnormalities. Unenhanced sequences were necessary for accurate interpretation of the enhanced images (e.g., identification or exclusion of hemorrhage). The combination of unenhanced and enhanced MR imaging is recommended for the detection of residual or recurrent meningioma after surgery.     

无症状女性触诊阴性乳腺癌非增强扩散加权和T2加权MRI的检出:与乳腺X线摄影和对比增强MRI的对照研究

目的对照比较无症状女性触诊阴性乳腺癌乳腺X线摄影(MMG)、动态增强MRI(DCE-MRI)和扩散加权联合T2加权的非增强MRI(DWI+T2WI)的病变检出能力。方法     

Diagnosis of cerebral metastases: double-dose delayed CT vs contrast-enhanced MR imaging

For patients suspected of having cerebral metastases, double-dose delayed CT (DDD-CT) has proved significantly more sensitive than CT scans obtained immediately after administration of a lesser dose of iodinated contrast material. Previous reports confirm the advantages of postcontrast MR imaging over contrast-enhanced CT, but data comparing DDD-CT and contrast-enhanced MR have not been reported. This study describes comparative imaging results in 23 patients who had contrast-enhanced MR imaging to clarify equivocal findings on DDD-CT studies. Contrast-enhanced MR demonstrated more than 67 definite or typical parenchymal metastases. T2-weighted MR revealed more than 40, while DDD-CT revealed only 37 typical metastatic lesions. Three patients had five or fewer lesions on DDD-CT and lesions "too numerous to count" on MR. The frequency of equivocal or unconvincing lesions was similar on DDD-CT (11) and contrast-enhanced MR (10). On T2-weighted images, we noted a substantially higher number of equivocal lesions (19), fewer definite metastases, and a number of definite metastases that had no corresponding lesion on the enhanced studies, confirming the inability of T2-weighted imaging to specifically identify cerebral metastases. In one case, multiple tiny lesions on T2-weighted images were not apparent on DDD-CT scans and were recognized only in retrospect on contrast-enhanced MR images. In this series, MR with enhancement proved superior to DDD-CT for lesion detection, anatomic localization of lesions, and differentiation of solitary vs multiple lesions. Cost-benefit considerations precluded a comparison between the two techniques in all patients suspected of having cerebral metastases.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhanced mass on contrast-enhanced breast MR imaging: Lesion characterization using combination of dynamic contrast-enhanced and diffusion-weighted MR images

Purpose

To evaluate the diagnostic accuracy of a combination of dynamic contrast‐enhanced MR imaging (DCE‐MRI) and diffusion‐weighted MR imaging (DWI) in characterization of enhanced mass on breast MR imaging and to find the strongest discriminators between carcinoma and benignancy.

Materials and Methods

We analyzed consecutive breast MR images in 270 patients; however, 13 lesions in 93 patients were excluded based on our criteria. We analyzed tumor size, shape, margin, internal mass enhancement, kinetic curve pattern, and apparent diffusion coefficient (ADC) values. We applied univariate and multivariate analyses to find the strongest indicators of malignancy and calculate a predictive probability for malignancy. We added the corresponding categories to these prediction probabilities for malignancy and calculated diagnostic accuracy when we consider category 4b, 4c, and 5 lesions as malignant and category 4a, 3, and 2 lesions as benign. In a validation study, 75 enhancing lesions in 71 patients were examined consecutively.

Results

Irregular margin, heterogeneous internal enhancement, rim enhancement, plateau time–intensity curve (TIC) pattern, and washout TIC pattern were the strongest indicators of malignancy as well as past studies, and ADC values less than 1.1 × 10^?3 mm²/s were also the strongest indicators of malignancy. In a validation study, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 92% (56/61), 86% (12/14), 97% (56/58), 71% (12/17), and 91% (68/75), respectively.

Conclusion

The combination of DWI and DCE‐MRI could produce high diagnostic accuracy in the characterization of enhanced mass on breast MR imaging. J. Magn. Reson. Imaging 2008;28:1157–1165. © 2008 Wiley‐Liss, Inc.

     

Non-mass-like enhancement on contrast-enhanced breast MR imaging: Lesion characterization using combination of dynamic contrast-enhanced and diffusion-weighted MR images

Purpose

To evaluate the diagnostic accuracy of a combination of dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted MR imaging (DWI) in characterization of lesions showing non-mass-like enhancement on breast MR imaging and to find the strongest discriminators between carcinoma and benignancy.

Materials and methods

We analyzed consecutive MR images in 45 lesions showing non-mass like enhancement in 41 patients. We analyzed lesion size, distribution, internal enhancement, kinetic curve pattern, and apparent diffusion coefficient (ADC) values. We applied univariate and multivariate analyses to find the strongest indicators for malignancy. In a validation study, 22 non-mass-like enhancement lesions in 21 patients were examined. We calculated diagnostic accuracy when we presume category 4b, 4c, and 5 lesions as malignant or high to moderate suspicion for malignancy, and category 4a and 3 as low suspicion for malignancy or benign.

Results

Segmental distribution (P = 0.018), clumped internal enhancement (P = 0.005), and ADC less than 1.3 × 10⁻³ mm²/s (P = 0.047) were the strongest MR indicators of malignancy. In a validation study, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 87% (13/15), 86% (6/7), 93% (13/14), 75% (6/8) and 86% (19/22), respectively.

Conclusion

The combination of DCE-MRI and DWI showed high diagnostic accuracy in characterization of non-mass-like enhancement lesions on breast MR images.     

Quantitative dynamic contrast-enhanced MR imaging analysis of complex adnexal masses: a preliminary study

Objective  

To evaluate the ability of quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to differentiate malignant from benign adnexal tumours.     

定量动态对比增强MRI分析复杂性附件肿块:初步研究

目的评价定量动态对比增强MRI(DCE-MRI)鉴别附件良恶性肿瘤的能力。方法56例患有复杂性附件肿块的妇女于术前行MR成像,其中38例恶性和18例良性。于附件肿瘤的实性组织应用药物代谢动力学模型,从高时间分辨力DCE-MRI序列中获取微血管参数。这些参数是组织血     

Parotid masses: MR imaging

Over a 2-year period 20 patients who presented with masses in the parotid gland were evaluated with magnetic resonance (MR) imaging. T1-weighted images were obtained on a high-resolution, thin-section MR imaging system. When "cystic-appearing" lesions were found, T2-weighted images were obtained in order to better characterize the tumor. As in other areas of the body, MR images of parotid tumors are not usually histologically specific. MR findings may be distinctive in rare cases and define the internal architecture of complex parotid masses. Although poor tumor margination was a clue to malignancy, this was not a consistent finding. The real advantage of MR imaging in evaluating parotid masses was its ability to accurately reveal the extraparotid or intraparotid location of a tumor and demonstrate the relationship of the tumor to the facial nerve. Small and medium-sized mass lesions could be seen as superficial or deep to the facial nerve. Larger masses producing some distortion of the normal course of the nerve made identification of the nerve more difficult, if not impossible. In malignant tumors with gross invasion of the facial canal, MR images can show the extent of nerve involvement.     

Mediastinal masses: MR imaging

Seventy-five patients with mediastinal masses were imaged with magnetic resonance (MR). Results were analyzed with regard to the ability of MR to demonstrate the masses, their morphology, and their encroachment or displacement of blood vessels and airways. T1 values were determined in 53 patients and T2 values in 59. Hydrogen density and percentage of contrast relative to muscle and fat were also obtained in 53 and 59 patients, respectively. MR images were compared with computed tomography (CT) scans, which were available in 45 patients. MR depicted all masses and demonstrated compromise of vessels and cardiac chambers owing to the inherent contrast between the masses and cardiovascular structures. Bronchogenic carcinoma had very long relaxation values for T1 and T2, while chronic inflammatory processes had intermediate values for T1 and T2, thus appearing less intense than bronchogenic carcinoma on T2-weighted images. Other neoplasms demonstrated T1 and T2 values between these two disease groups. Masses appeared less homogeneous on MR images than on CT scans, and vascular compromise was better assessed with MR. Thus, MR imaging is a completely noninvasive technique for the evaluation of mediastinal masses. While the anatomic information is comparable to that produced by CT, MR provides some insight into the composition of the mass.     

MR imaging of large and rare pelvic masses from non-gynecological etiology

The diagnosis and characterization of pelvic masses may be problematic, especially when they are larger than 5 cm in diameter. The majority of large pelvic masses in women originate from gynecological structures. However, they may also originate from the GI tract, urinary tract, retroperitoneum, pelvic soft tissue structures, peritoneum and bones. MRI is the imaging modality of choice because it provides excellent contrast resolution and allows direct multiplanar imaging capabilities. Diagnosis is usually suggested after careful evaluation of the tumor location, anatomical relationships, morphology and signal characteristics. In this article, we will discuss the MR imaging features of large rare pelvic masses of non-gynecological origin, along with associated clinical and histological findings.     

Detection of brain metastases: comparison of contrast-enhanced MR with unenhanced MR and enhanced CT

Contrast-enhanced MR studies were compared with noncontrast MR and contrast-enhanced CT scans in the evaluation of intraparenchymal brain metastases. Fifty consecutive inpatients were studied with short and long repetition time (TR) sequences before and after the administration of gadopentetate dimeglumine. In addition, a delayed short TR sequence was performed. The contrast CT, noncontrast MR, immediate postcontrast short TR sequence, postcontrast long TR sequence, and delayed postcontrast short TR sequence were each read blindly and independently by two neuroradiologists. These results were then compared with a final interpretation, reached by all the neuroradiologists in the study, using all the clinical information and imaging findings. Postcontrast short TR scans proved to be superior to other sequences. They were particularly useful in the detection of metastases in the posterior fossa and cortex. The delayed postcontrast short TR scan held no definite advantage over the immediate postcontrast short TR scan, although metastases were sometimes seen slightly better after the delay. While long TR sequences were not always sensitive or specific, they often did provide ancillary information and were particularly useful in cases of hemorrhagic metastases. Because of these findings, we recommend that the evaluation of intraparenchymal metastases consist of a single postcontrast long TR scan followed by a single postcontrast short TR scan. While these sequences should be very accurate in the detection of metastases, we also generally perform a single precontrast short TR scan as well, since the question of hemorrhage or bone lesion may be clinically relevant.     

Evaluation of focal pancreatic masses: comparison of mangafodipir-enhanced MR imaging and contrast-enhanced helical CT

The detection and characterization of pancreatic tumors as well as the reliable staging of pancreatic cancer are important tasks for radiologic evaluation. Contrast-enhanced helical CT has been the standard modality for pancreatic imaging in many institutions, but MR imaging has gained a considerable role in the evaluation of patients with equivocal CT findings. Recently, the first organ-specific MR contrast agent targeted to the liver and pancreas, mangafodipir trisodium, has been registered in the European Union (EU) for use in MR imaging of the pancreas. This paper reviews technical considerations and characteristic imaging findings of mangafodipir-enhanced MR imaging in the assessment of focal pancreatic lesions. Contrast-enhanced MRI has proven to be very helpful in the detection of small tumors or the identification of tumor-simulating lesions in patients with equivocal CT findings. Mangafodopir may improve the staging of pancreatic cancer by increasing the sensitivity of MRI in the detection of liver metastases. This review summarizes the potential of contrast-enhanced MRI and the limitations compared with contrast-enhanced helical CT. Electronic Publication     

Gadolinium-enhanced MR imaging of renal masses.

Preliminary reports indicate that gadolinium-enhanced magnetic resonance (MR) imaging is highly accurate for diagnosis of renal masses. The authors demonstrate the clinical utility of MR imaging for evaluating renal masses in 26 patients for whom contrast material-enhanced computed tomography (CT) was contraindicated or inadequate for diagnosis or staging. Nine patients had complex cysts, one had a perinephric hematoma, and 16 had a solid mass (three of which were benign). All patients underwent MR imaging before and after administration of gadopentetate dimeglumine. Multiple imaging techniques and sequences were used. All tumors and no cysts enhanced with gadolinium. Even though the three benign tumors enhanced, two were differentiated from renal carcinoma on the basis of other imaging features. Unenhanced MR imaging was accurate in staging of renal carcinomas, and use of gadolinium did not improve staging accuracy. Gadolinium-enhanced MR imaging is indicated when results of CT and sonography are indeterminate for malignancy and when contrast-enhanced CT is contraindicated because of renal failure or adverse reaction to iodinated contrast material. In this latter instance, MR imaging is useful for both diagnosis and staging.