Prospective evaluation of pancreatic tumors: accuracy of MR imaging with MR cholangiopancreatography and MR angiography

PURPOSE: To prospectively assess accuracy of magnetic resonance (MR) imaging, MR cholangiopancreatography (MRCP), and MR angiography in patients suspected of having pancreatic tumors. MATERIALS AND METHODS: Sixty-six patients suspected of having pancreatic tumors underwent MR imaging (unenhanced and contrast material-enhanced MR, MRCP, and contrast-enhanced MR angiography). Two blinded readers prospectively analyzed the images by consensus, and results were correlated with surgery, biopsy, or follow-up findings. Results were tabulated in two-by-two tables. RESULTS: MR assessment of pancreatic lesion status (differentiation of benign vs malignant) resulted in 60 correct diagnoses (accuracy, 91%), and six (10%) false diagnoses. Among histologically proved malignant tumors, MR imaging yielded correct diagnoses in 42 of 44 patients (sensitivity, 95%; 95% CI: 85%, 99%), whereas 18 of 22 patients with benign findings were classified correctly. At MR imaging, findings in four patients with chronic pancreatitis were wrongly categorized as malignant tumors (specificity, 82%; 95% CI: 60%, 95%), and in one patient, a distal common bile duct carcinoma was not detected. In no patient with pancreatic adenocarcinoma was this tumor misdiagnosed as benign. In patients with malignant tumors who underwent resection, local-regional tumor growth and vascular infiltration were accurately classified in 89% and 94%, respectively. MR imaging depicted histologically proved synchronous hepatic metastases in 82%. The positive and negative predictive values for cancer nonresectability were 90% and 83%, respectively, and the accuracy, sensitivity, and specificity were 85%, 69%, and 95%, respectively. CONCLUSION: Unenhanced and contrast-enhanced MR imaging with MRCP and MR angiography offers potential as a noninvasive tool for assessment of patients suspected of having pancreatic tumors.     

Role of diffusion-weighted echo-planar MR imaging in differentiation of residual or recurrent head and neck tumors and posttreatment changes

BACKGROUND AND PURPOSE: The purpose of this work was to evaluate whether diffusion-weighted MR imaging can be used in differentiating residual or recurrent head and neck tumors from postoperative or postradiation changes. MATERIALS AND METHODS: This study included 32 patients clinically suspected for recurrent head and neck tumor after surgery (n=3), radiation therapy (n=13), or both (n=16). Diffusion-weighted MR imaging was done by using a single-shot spin-echo echo-planar sequence. The apparent diffusion coefficient (ADC) value of the suspected lesion was calculated and correlated with pathologic results. RESULTS: Adequate diffusion-weighted MR images and ADC maps were obtained in 30 patients (93.8%). The mean ADC value of residual or recurrent lesions (1.17 +/- 0.33 x 10(-3) mm(2)/s) was less than that of posttherapeutic changes (2.07 +/- 0.25 x 10(-3) mm(2)/s), and the difference was statistically significant (P<.001). When an ADC value of 1.30 x 10(-3) mm(2)/s was used as a threshold value for differentiation, the best results were obtained with an accuracy of 87%, sensitivity of 84%, specificity of 90%, positive predictive value of 94%, and negative predictive value of 76%. CONCLUSIONS: Diffusion-weighted MR imaging with ADC measurement has promising results for differentiating residual or recurrent head and neck tumors from postoperative or postradiation changes.     

Usefulness of whole-body (18)F-FDG PET in patients with suspected metastatic brain tumors.

The aim of this study was to evaluate the diagnostic value of whole-body (18)F-FDG PET imaging in the differentiation of metastatic brain tumor from primary brain tumor and in the localization of the primary lesion in patients with metastatic brain tumor. METHODS: The subjects consisted of 127 patients (77 men, 50 women; mean age +/- SD, 55 +/- 12 y) with brain masses that were suspected to be metastatic brain tumors on radiologic studies: 77 with confirmed metastatic brain tumor and 50 with primary brain tumor. Whole-body (18)F-FDG PET was performed on all patients. When the abnormal lesion was detected outside the brain, we interpreted the brain lesion as metastatic brain tumor. RESULTS: In 61 of the 77 patients with metastatic brain tumor, primary lesions were detected using whole-body (18)F-FDG PET. Of the remaining 16 patients (all false-negative cases), 7 were classified as metastases of unknown origin. In 47 of the 50 patients with primary brain tumor, whole-body (18)F-FDG PET did not show any other abnormal lesions. The sensitivity, specificity, positive and negative predictive values, and accuracy of PET for the detection of primary origin were 79.2%, 94.0%, 95.3%, 74.6%, and 85.0%, respectively. The most common primary origin of metastatic brain tumors on PET examination was lung cancer (48/61, 78.7%). The concordance rate between (18)F-FDG PET and conventional radiologic work-up was 80% in identifying primary lesion. Unknown bone or bone marrow metastases and unsuspected distant metastases were found in 14 patients (18%) and 24 patients (31%), respectively, on PET examination. CONCLUSION: Screening the patients with suspected metastatic brain tumors using whole-body (18)F-FDG PET could be helpful in differentiating metastatic brain tumor from primary brain tumor and in detecting the primary lesion.     

Cervical carcinoma: optimized local staging with intravaginal contrast-enhanced MR imaging--preliminary results.

Ten patients suspected of having cervical carcinoma underwent magnetic resonance (MR) imaging before and after opacification of the vagina with a mixture of barium, water, and maltodextrin/calcium lactate. Use of vaginal contrast medium resulted in improved visualization of the vaginal wall, lumen, and fornices in all patients and in a change in local tumor stage in two patients (20%). This technique may contribute to improved noninvasive staging of cervical carcinoma.     

Vagina: evaluation with MR imaging. Part I. Normal anatomy and congenital anomalies

The appearance of the vagina was evaluated on magnetic resonance (MR) images of 65 subjects who were healthy or had disease unrelated to the vagina and 24 patients with suspected congenital anomalies of the vagina. MR imaging accurately demonstrated the presence of (n = 78) or complete (n = 7) or partial (n = 4) absence of the vagina in each case. Partial (n = 2) or complete (n = 2) duplication of the vagina was also correctly diagnosed. Regardless of field strength, T2-predominant images were essential for evaluation. The transverse plane was optimal, and a 5-mm section thickness was preferable. Estrogen stimulation affected the appearance of the vagina: The contrast between the vaginal wall and the central mucus-containing area was greatest during the early proliferative and late secretory phases. MR imaging offers unique depiction of congenital anomalies and should be used when results of physical examination or other radiologic studies, such as ultrasound, are inconclusive.     

Value of combined FDG PET and MR imaging in the evaluation of suspected recurrent local-regional breast cancer: preliminary experience

PURPOSE: To assess the performance and potential clinical effects of combined 2-[fluorine 18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) and magnetic resonance (MR) imaging of the axilla and brachial plexus in patients suspected of having local-regional breast cancer metastases. MATERIALS AND METHODS: Upper-body FDG PET and axillary and supraclavicular MR imaging were performed in 10 patients (age range, 45-71 years) with clinical findings suggestive of breast cancer metastases. Medical records were reviewed retrospectively. Imaging findings were correlated with clinical data and follow-up findings in all patients. Surgical findings were available in four patients. RESULTS: Nine patients had local-regional breast cancer metastases. MR imaging was diagnostic for tumor in five patients and was indeterminate in four patients with axillary or chest wall metastases. With FDG PET, metastatic tumor was positively identified in all nine patients. MR imaging was useful for determining the relationship of metastatic tumor to axillary and supraclavicular neurovascular structures. FDG PET helped confirm metastases in patients with indeterminate MR imaging findings and depicted unsuspected metastases outside the axilla. CONCLUSION: MR imaging and FDG PET are complementary in detecting and characterizing local-regional breast cancer metastases. Combined FDG PET and MR imaging provide useful treatment-planning data for patients clinically suspected of having recurrent axillary or supraclavicular breast cancer.     

Invasive cervical carcinoma: comparison of MR imaging and surgical findings

The accuracy of magnetic resonance (MR) imaging in staging invasive carcinoma of the cervix was determined retrospectively in 57 consecutive patients in whom the extent of disease was surgically confirmed. MR images were analyzed for (a) location and size of the primary tumor; (b) tumor extension to the uterine corpus, vagina, parametria, pelvic sidewall, bladder, or rectum; and (c) pelvic lymphadenopathy. The accuracy of MR imaging in determination of tumor location was 91% and for determination of tumor size within 0.5 cm, 70%. Its accuracy was 93% for vaginal extension and 88% for parametrial extension. Pelvic sidewall, bladder, and rectal involvement were accurately excluded in all patients, but the positive predictive values were 75%, 67%, and 100%, respectively. Overall, the accuracy of MR imaging in staging was 81%. MR imaging is valuable because it can accurately demonstrate tumor location, tumor size, degree of stromal penetration, and lower uterine segment involvement. It is also valuable for ruling out parametrial, pelvic sidewall, bladder, and rectal involvement.     

Common occurrence of benign liver lesions in patients with newly diagnosed breast cancer investigated by MRI for suspected liver metastases.

The purpose of this study was to determine the prevalence of benign liver lesions in patients with breast cancer who are referred to magnetic resonance (MR) imaging for suspected breast cancer metastases at initial presentation. The original MR imaging reports of consecutive patients with breast cancer were reviewed; these patients had undergone MR imaging at our institution to investigate for suspected breast cancer liver metastases, at initial presentation between April 1993 and May 1998. Determination of the presence of benign and malignant liver lesions in each patient was made, as well as their relative frequencies. Diagnostic accuracy of MR imaging was evaluated by correlation with histologic specimens (5 patients) and imaging follow-up (27 patients). Thirty-four patients with newly diagnosed breast carcinoma were evaluated with MR imaging. A total of 11 (32%) of these patients had benign lesions only. Of 21 (62%) total patients who had malignant liver lesions, 19 had breast cancer metastases (2 had coexistent benign lesions), 1 had metastatic carcinoid, and 1 had hepatocellular carcinoma. No liver lesions were detected in two patients (6%). In one patient with biopsy-proven subcentimeter breast metastases, no focal lesions were shown on MR imaging. No other diagnostic errors in classification of liver lesions by MR imaging occurred, as shown by clinical correlation and imaging follow-up in all patients. True positive detection of malignant liver lesion was 20/21, true negative was 13/13, false positive was 0/13, and false negative was 1/21, for a sensitivity of 95% and a specificity of 100% for the detection of malignant liver lesions. Benign liver lesions are common in breast cancer patients suspected clinically of having liver metastases. Benign lesions alone were observed in one-third of our patients. The high diagnostic accuracy of MR imaging in the evaluation of hepatic lesions underscores the value of this technique for baseline investigation of breast cancer patients with clinically suspected liver metastases, particularly patients in whom treatment approaches are dramatically affected by the presence of liver metastases. J. Magn. Reson. Imaging 1999;10:165-169.     

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.     

Retrospective analysis of 31 cases of soft tissue tumors. Comparison of MR and surgical and anatomo-pathological findings

Twenty-five patients (16 with malignant soft-tissue tumors and 9 with suspected recurrence), previously studied with conventional radiography and Computed Tomography (CT), were examined with Magnetic Resonance (MR) imaging. MR findings were surgically and anatomo-histopathologically confirmed. Six more patients with benign lesions were examined for differential diagnosis. MR capabilities are here evaluated to detect and eventually characterize the lesion, and to assess its exact location. No false positives were found, and there was only one false negative, in a case of recurrent Malignant Fibrous Histiocytoma (MFH). In another case of MFH the infiltration of the adjacent vessels and nerves was not imaged. After a careful review of all the examinations, MR imaging appears to be able to provide much information for surgical planning about tumor extent and margins, thanks to its contrast resolution between tumor and surrounding anatomical structures. Therefore, MR imaging can be reasonably employed as the examination of choice when a soft-tissue tumor is clinically suspected, because of the multi-planar images it provides with and of its differential imaging parameters.     

Diagnosis and staging of pancreatic cancer: comparison of mangafodipir trisodium-enhanced MR imaging and contrast-enhanced helical hydro-CT

OBJECTIVE: The purpose of this study was to compare mangafodipir trisodium-enhanced MR imaging performed with a phased array coil and contrast-enhanced single-detector helical CT for accuracy in the detection and local staging of pancreatic adenocarcinoma and in the differentiation between cancer and focal pancreatitis. SUBJECTS AND METHODS: Forty-two patients with suspected pancreatic masses underwent contrast-enhanced helical CT and mangafodipir trisodium-enhanced MR imaging at 1.5 T. The images were assessed for the presence or absence of tumors; characterization of masses; and presence of vascular invasion, lymph node metastases, or liver metastases. Imaging findings were correlated with findings at laparotomy, laparoscopy, biopsy, or follow-up. RESULTS: Focal masses were present in 36 patients (cancer, n = 26; focal pancreatitis, n = 7; other, n = 3). The sensitivity for lesion detection of MR imaging was 100% and of CT, 94%. Two small malignant lesions were missed on CT. For the diagnosis of tumor nonresectability, the sensitivity of MR imaging and CT was 90% and 80%, respectively. Liver metastases were missed on MR imaging in one of the eight patients and on CT in four. For differentiation between adenocarcinoma and nonadenocarcinoma, the sensitivity of MR imaging was 100% (positive predictive value, 90%; negative predictive value, 100%), and the sensitivity of CT was 92% (positive predictive value, 80%; negative predictive value, 67%). Receiver operating characteristic analysis revealed that the mean area under the curve for MR imaging was 0.920 and for CT, 0.832 (not significant). CONCLUSION: Mangafodipir trisodium-enhanced MR imaging is as accurate as contrast-enhanced helical CT for the detection and staging of pancreatic cancer but offers improved detection of small pancreatic metastases and of liver metastases compared with CT.     

应用MR全身扩散加权成像寻找转移瘤原发灶的初步研究

目的 探讨MR全身扩散加权成像(DWI)寻找转移瘤患者原发灶的可行性和灵敏度.方法 前瞻性分析34例以转移瘤症状就诊,经CT、单光子发射计算机体层成像或MRI发现不明原发灶的转移瘤患者进行全身DWI扫描,分别测量可疑原发灶和转移瘤的表观扩散系数(ADC)值.对经活检或手术病理证实的肺癌患者,应用配对t检验比较原发灶和转移瘤的ADC值.探讨全身DWI对原发灶的检出率和灵敏度.结果 通过对34例转移瘤患者全身DWI扫描,发现可疑原发灶24例,其中23例被证实为原发恶性肿瘤,1例可疑原发灶穿刺为良性病变;10例经全身DWI扫描未发现明确原发灶,其中2例经活检明确原发灶,8例经随访6～12个月仍未明确原发灶.确诊的14例肺癌原发灶和转移瘤的平均ADC值分别为(1.24±0.18)×10-3和(1.16±0.27)×103mm2/s,差异无统计学意义(t=1.28,P>0.05).全身DWI对原发灶的检出率为67.6%(23/34),灵敏度为92.0%(23/25).结论 全身DWI对转移瘤患者寻找原发灶的灵敏度高,可以作为寻找原发灶的筛查方法.     

MR staging of clinical stage I and IIa cervical carcinoma: a reappraisal of efficacy and pitfalls

The purpose of this study was to evaluate the diagnostic efficacy and pitfalls of magnetic resonance (MR) imaging in preoperative staging of cervical cancer. MR imaging was performed to determine the tumor staging for 31 patients with cervical carcinoma emphasizing tumor size, parametrial invasion, vaginal invasion and lymph node metastases. Tumor size was 3.23+/-1.75 cm (mean+/-standard deviation) at MR imaging compared with 2.79+/-1.76 cm at surgical-pathologic evaluation. The discrepancy between the tumor size determined by MR imaging and the measured surgical specimens was consistent in tumors larger than 1 cm. In assessing parametrial invasion, vaginal invasion and lymph node metastases, MR imaging had an accuracy of 96.7 and 87%. In determining stage of disease and differentiating operable (< or =stage IIA) from advanced disease (> or =stage IIB), MR imaging had an accuracy of 83.8 and 96.7%. Pitfalls leading to staging errors included difficulties in differentiating cancer foci from surrounding tissue edema and excluding vaginal invasion in the presence of large cervical cancer. In conclusion, MR imaging is accurate in the evaluation of parametrial invasion and useful in the differentiation of operable from advanced disease. The ability of MR imaging to exclude vaginal invasion in the presence of large cervical cancer and differentiate cancer foci from surrounding tissue edema is not as reliable.     

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.     

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.     

Preoperative staging of cervical carcinoma with MR imaging: a reappraisal of diagnostic accuracy and pitfalls

The purpose of this study was to assess the diagnostic accuracy and pitfalls of MR imaging in preoperative staging of cervical cancer. Magnetic resonance imaging was performed to determine the tumor staging for 41 patients with cervical carcinoma emphasizing tumor size, parametrial invasion, vaginal invasion, and lymph node metastases. According to the correlation of MR findings with surgical-pathological features, there was less than 5 mm discrepancy in the size in 29 of 34 tumors (85.3%) that were larger than 1 cm. In assessing parametrial invasion, vaginal invasion and lymph node metastases, MR imaging had an accuracy of 95, 83, and 86%, respectively. In determining stage of disease and differentiating operable (< or =stage IIA) from advanced disease (> or =stage IIB), MR imaging had an accuracy of 82.9 and 93%. Pitfalls leading to staging errors included difficulties in differentiating cancer foci from surrounding tissue edema and detecting microscopic tumor extension. Magnetic resonance imaging is accurate in the evaluation of parametrial invasion and differentiation of operable from advanced disease. The ability of MR imaging to detect microscopic extra-cervical tumor extension and differentiate cancer foci from surrounding tissue edema is not as reliable.     

动态增强MRI对软组织肿块良、恶性的鉴别诊断价值

目的 评价动态增强MRI对软组织肿块和肿瘤样病变的良、恶性的鉴别价值。方法 对30例经病理证实的软组织肿块进行动态增强扫描，其中恶性肿瘤11例，良性肿块19例。将感兴趣区(ROI)的信号强度绘制成时间-信号强度曲线(TIC)，并分别计算其0．5min斜率值。结果 30例软组织肿块的TIC分为3型，12例表现为I型曲线，其中10例为恶性肿瘤，2例为良性肿瘤；12例表现为Ⅱ型曲线，其中11例为良性肿块，1例为恶性肿瘤；6例表现为Ⅲ型曲线，均为良性肿块。11例恶性肿瘤中，10例病变的0．5min斜率值大于0．0057；19例良性肿块中，17例0．5min斜率小于0．0057；良、恶性肿瘤的TIC斜率值之间存在显著性差异，Logistic回归分析病变良、恶性和斜率值有相关性。以0．5min斜率值0．0057作为鉴别肿块良恶性的阈值，判断肿块良、恶性的敏感性为90．9%，特异性为89．4％，阳性预测值为83．3％，阴性预测值为94．4％。结论 动态增强MRI可以较准确地预测肿瘤病变的良、恶性。     

Gastrinomas: comparison of MR imaging with CT, angiography, and US

In this prospective study, magnetic resonance (MR) imaging was used to localize gastrinoma in 24 patients with Zollinger-Ellison syndrome. The results were confirmed by means of either surgery or percutaneous liver biopsy and compared with results of computed tomographic (CT) scanning, selective abdominal angiography, and abdominal ultrasound (US). For primary extrahepatic gastrinoma (intra-or extrapancreatic), MR imaging had a sensitivity of 20% and a specificity of 100%, with a positive predictive value of 100% and a negative predictive value of 11%. For metastatic gastrinoma in the liver, MR imaging had a sensitivity of 43% and a specificity of 100%, with a positive predictive value of 100% and a negative predictive value of 81%. The ability of MR imaging to depict extrahepatic gastrinomas was directly related to tumor size; no tumors smaller than 1 cm were detected, and 50% of tumors 3 cm or larger were detected. MR imaging was as effective as abdominal US but less effective than either CT scanning or selective abdominal angiography for the detection of extrahepatic gastrinoma. In seven patients with hepatic gastrinoma, three gastrinomas were detected with MR imaging and with abdominal US, while five were detected with CT scanning and with selective abdominal angiography. These results indicate that, at the present time, MR imaging is generally not useful in the initial attempt to localize gastrinomas.     

Treated ovarian cancer: comparison of MR imaging with serum CA-125 level and physical examination--a longitudinal study

PURPOSE: To evaluate whether gadolinium-enhanced magnetic resonance (MR) imaging can demonstrate clinically occult tumors in women with treated ovarian cancer and to compare the diagnostic accuracy of MR imaging, serum CA-125 (ovarian cancer antigen) level, and physical examination. MATERIALS AND METHODS: From 1992 to 1997, a longitudinal study comparing MR imaging findings, CA-125 values, and physical examination results with eventual clinical outcome in 69 women with treated ovarian cancer was performed. Tumor presence was determined with surgery, by an elevated CA-125 value, or with follow-up of patients longitudinally to assess for tumor recurrence. Absence of tumor was accepted with a disease-free interval of at least 2 years. RESULTS: Twenty-three of 39 patients in clinical remission with a normal CA-125 level and physical examination result had subclinical tumor proved at laparotomy or clinical follow-up. Gadolinium-enhanced MR imaging correctly demonstrated residual tumor in 20 of 23 patients. In all 69 patients, MR images had a 91% sensitivity, 87% specificity, 90% accuracy, and 72% negative predictive value and were superior to serum CA-125 level (53%, 94%, 63%, and 38%, respectively) (P < .001) and physical examination (26%, 94%, 43%, and 29%, respectively) (P < .001) in the depiction of residual tumor. CONCLUSION: Gadolinium-enhanced MR imaging is a valuable clinical tool in patients with ovarian cancer. An abnormal MR examination with a normal CA-125 value is a strong indication of residual or recurrent tumor.     

Diagnostic imaging of mediastinal masses in children.

Mediastinal masses are the most common thoracic masses in children. The encyclopedic list of diagnostic considerations can be distilled into a concise and practical differential diagnosis based on the location of the mass and the established prevalence of various tumors and pseudotumors in the mediastinal compartments. Malignant lymphoma, benign thymic enlargement, teratomas, foregut cysts, and neurogenic tumors make up 80% of mediastinal masses in children. Continuing advances in imaging technology have altered traditional approaches to the evaluation and diagnosis of mediastinal masses in children. Plain chest radiography remains the basic imaging examination to define location and morphology. Cross-sectional imaging subsequently clarifies the morphology and extent of the mass. In general, CT is the primary cross-sectional imaging procedure in the evaluation of most mediastinal masses in children. Exceptions to this rule include MR in children with posterior mediastinal masses or suspected vascular lesions: in such cases, MR imaging is the preferred initial postradiographic examination. Sonographic examination may be diagnostic in foregut cysts and some other mediastinal masses. Gallium-67 scintigraphy has an emerging role in management of malignant lymphoma.