The utility of in-phase/opposed-phase imaging in differentiating malignancy from acute benign compression fractures of the spine.

BACKGROUND AND PURPOSE: Benign and malignant fractures of the spine may have similar signal intensity characteristics on conventional MR imaging sequences. This study assesses whether in-phase/opposed-phase imaging of the spine can differentiate these 2 entities. METHODS: Twenty-five consecutive patients who were evaluated for suspected malignancy (lymphoma [4 patients], breast cancer [3], multiple myeloma [2], melanoma [2], prostate [2], and renal cell carcinoma [1]) or for trauma to the thoracic or lumbar spine were entered into this study. An 18-month clinical follow-up was performed. Patients underwent standard MR imaging with an additional sagittal in-phase (repetition time [TR], 90-185; echo time [TE], 2.4 or 6.5; flip angle, 90 degrees ) and opposed-phase gradient recalled-echo sequence (TR, 90-185, TE, 4.6-4.7, flip angle, 90 degrees ). Areas that were of abnormal signal intensity on the T1 and T2 sequences were identified on the in-phase/opposed-phase sequences. An elliptical region of interest measurement of the signal intensity was made on the abnormal region on the in-phase as well as on the opposed-phase images. A computation of the signal intensity ratio (SIR) in the abnormal marrow on the opposed-phase to signal intensity measured on the in-phase images was made. RESULTS: Twenty-one patients had 49 vertebral lesions, consisting of 20 malignant and 29 benign fractures. There was a significant difference (P < .001, Student t test) in the mean SIR for the benign lesions (mean, 0.58; SD, 0.02) compared with the malignant lesions (mean, 0.98; SD, 0.095). If a SIR of 0.80 as a cutoff is chosen, with >0.8 defined as malignant and <0.8 defined as a benign result, in-phase/opposed-phase imaging correctly identified 19 of 20 malignant lesions and 26 of 29 benign lesions (sensitivity, 0.95; specificity, 0.89). CONCLUSION: There is significant difference in signal intensity between benign compression fractures and malignancy on in-phase/opposed-phase MR imaging.

Paraovarian cyst: MR imaging features.

BACKGROUND: Paraovarian cysts are common intrapelvic neoplasms, but the magnetic resonance (MR) findings of paraovarian cyst have never been reported. We investigated the spectrum of MR imaging features of paraovarian cyst. METHODS: MR images of 18 paraovarian cysts in 16 patients were reviewed retrospectively. MR images were evaluated for the size and location of paraovarian cysts, single or multicystic, signal intensity on T1- and T2-weighted images, and visualization of the normal ovary on the affected side. RESULTS: The normal ovary of the affected side was recognized in 13 lesions. Four of these 13 cysts were separated from the ipsilateral ovary. In seven cysts, the normal ovary was abutted by cysts but maintained its shape. In two cysts, the beak sign was recognized at the interface between the cyst and the ovary. Most other MR features were nonspecific. CONCLUSION: Most paraovarian cysts were homogeneous cystic masses near the ipsilateral round ligament and the uterus. Demonstration of a normal ipsilateral ovary close to, but separated from, the adnexal cyst may be an important MR finding for the diagnosis of paraovarian cysts.

Magnetic resonance imaging of the ovary.

Magnetic resonance imaging (MRI) of the pelvis can characterize a wide variety of ovarian lesions. We discuss MRI strategies for identification and characterization of ovarian neoplasms and correlate MRI findings with lesion gross pathological and histopathological structure.

Ovarian teratomas: tumor types and imaging characteristics.

Ovarian teratomas include mature cystic teratomas (dermoid cysts), immature teratomas, and monodermal teratomas (eg, struma ovarii, carcinoid tumors, neural tumors). Most mature cystic teratomas can be diagnosed at ultrasonography (US) but may have a variety of appearances, characterized by echogenic sebaceous material and calcification. At computed tomography (CT), fat attenuation within a cyst is diagnostic. At magnetic resonance (MR) imaging, the sebaceous component is specifically identified with fat-saturation techniques. The US appearances of immature teratoma are nonspecific, although the tumors are typically heterogeneous, partially solid lesions, usually with scattered calcifications. At CT and MR imaging, immature teratomas characteristically have a large, irregular solid component containing coarse calcifications. Small foci of fat help identify these tumors. The US features of struma ovarii are also nonspecific, but a heterogeneous, predominantly solid mass may be seen. On T1- and T2-weighted images, the cystic spaces demonstrate both high and low signal intensity. Familiarity with the US, CT, and MR imaging features of ovarian teratomas can aid in differentiation and diagnosis.

Imaging evaluation of ovarian masses.

Adnexal masses present a special diagnostic challenge, in part because benign adnexal masses greatly outnumber malignant ones. Determination of a degree of suspicion for malignancy is critical and is based largely on imaging appearance. Endovaginal ultrasonography (US) is the most practical modality for assessment of ovarian tumors because it is readily available and has a high negative predictive value. Morphologic analysis of adnexal masses is accurate for identifying masses as either low risk or high risk. The most important morphologic features are non-fatty solid (vascularized) tissue, thick septations, and papillary projections. Color Doppler US helps identify solid, vascularized components in a mass. Spectral Doppler waveform characteristics (eg, resistive index, pulsatility index) correlate well with malignancy but generally add little information to morphologic considerations. Computed tomography can help assess the extent of disease in patients before and after primary cytoreductive surgery. Magnetic resonance (MR) imaging is better reserved for problem solving when US findings are nondiagnostic or equivocal because, although it is more accurate for diagnosis, it is also more expensive. The signal intensity characteristics of ovarian masses make possible a systematic approach to diagnosis. Mature cystic teratomas, cysts, endometriomas, leiomyomas, fibromas, and other lesions can be accurately diagnosed on the basis of T1-weighted, T2-weighted, and fat-saturated T1-weighted MR imaging findings.

Multicentre dose-ranging study on the efficacy of USPIO ferumoxtran-10 for liver MR imaging.

AIM: A dose ranging multicentre phase-II clinical trial was conducted to evaluate the efficacy of ultrasmall superparamagnetic iron oxide (USPIO) ferumoxtran-10 for magnetic resonance (MR) imaging of focal hepatic lesions. MATERIAL AND METHODS: Ninety-nine patients with focal liver lesions received USPIO at a dose of 0.8 (n = 35), 1.1 (n = 32), or 1.7 (n = 32) mg Fe/kg. Liver MR imaging was performed before and after USPIO with T1-weighted and T2-weighted pulse sequences. Images were analysed by two independent readers for additional information (lesion detection, exclusion, characterization and patient management). Signal intensity (SI) based quantitative measurements were also taken. RESULTS: Post-contrast medium MR imaging showed additional information in 71/97 patients (73%) for reader one and 83/96 patients (86%) for reader two. The results with all three doses were statistically significant (P < 0.05). Signal intensity analysis revealed that all three doses increased liver SI on T1-weighted images and decreased liver SI on T2-weighted images. On T2-weighted images metastases increased in contrast relative to normal hepatic parenchyma whereas haemangiomas decreased in contrast. On T2-weighted images there was statistically improved efficacy at the intermediate dose, which did not improve at the highest dose. CONCLUSION: Ultrasmall superparamagnetic iron oxide was an effective contrast agent for liver MR imaging at all doses and a dose of 1.1 mg Fe/kg was recommended for future clinical trials.

Virilizing tumors of the ovary: imaging features.

AIM: Virilizing tumors of the ovary are an uncommon cause of a common clinical problem. The reported imaging features of these tumors are based on case reports. The purpose of this study was to determine the spectrum of imaging characteristics of these tumors based on a larger referral population. PATIENTS AND METHODS: Case records from the Armed Forces Institute of Pathology were searched for clinical evidence of virilization as a presentation of an excised sex cord-stromal and steroid cell ovarian tumor. Records and imaging studies on 14 patients with virilizing tumors were found. All available imaging studies (ultrasound studies of the pelvis (11 patients), CT scans of the pelvis (five patients), MRI examinations of the pelvis (two patients), and plain films of the pelvis (four patients) were reviewed by three radiologists independently for ascites, calcification, percent solid portion, echogenicity and attenuation. RESULTS: On CT and/or ultrasound most (69%) of the tumors appeared to be solid or mostly solid. The amount of solid tissue varied with the tumor type, granulosa cell tumors were predominantly cystic. The masses were isoechoic (82%) or hypoechoic (18%). Ascites was an infrequent (23%) finding. Only a minority of these tumors (14%) were calcified on imaging studies. Six tumors were 5.0 cm or less in mean size, and two less than 3.0 cm in size. All cases were stage I tumors at presentation. CONCLUSION: The majority of virilizing tumors of the ovary are typically solid, noncalcified, confined to the ovary at presentation, and not associated with ascites. Variability in appearance depends in part on tumor type. Many are small and may be difficult to recognize as a mass morphologically.

Preoperative evaluation of living renal donors: comparison of CT angiography and MR angiography.

PURPOSE: To compare computed tomographic (CT) angiography and magnetic resonance (MR) angiography for preoperative evaluation of living renal donors. MATERIALS AND METHODS: Thirty-five living renal donors underwent preoperative contrast material-enhanced CT angiography and gadolinium-enhanced MR angiography. Each study was interpreted by two independent radiologists blinded to all other studies and to interpretations provided by other reviewers. Eighteen kidneys had surgical correlation. RESULTS: CT demonstrated 33 supernumerary arteries in 19 patients, bilateral solitary arteries in 16 patients, and 18 proximal arterial branches in 16 patients. MR demonstrated 26 supernumerary arteries in 15 patients, bilateral solitary renal arteries in 20 patients, and 21 proximal arterial branches in 16 patients. Interobserver agreements for MR (kappa = 0. 74) and CT (kappa = 0.73) were similar to the agreement between MR and CT (kappa = 0.74). Among the kidneys chosen for nephrectomy, one small accessory artery and one proximal arterial branch were missed with CT and MR. Two of the accessory arteries suggested at CT were not found at nephrectomy. By averaging data for both modalities, supernumerary arteries were present in 49% of kidney donors and were bilateral in approximately 17%. Proximal arterial branches were present in 46% of kidney donors. CONCLUSION: Preoperative CT and MR angiography of the renal arteries in renal donors demonstrate substantial agreement. Interobserver disagreement in the interpretation of CT and MR angiograms is related to 1-2-mm-diameter vessels.

MR imaging features of pelvic mucinous carcinomas.

Mucinous carcinomas in the pelvis differ from non-mucinous tumors because of the differences in clinical outcome and imaging appearance. Mucinous rectal carcinomas, for example, are to be higher in stage at the time of the diagnosis because they are more likely to be infiltrative and show a greater tendency for recurrence. These factors may lead to a poorer prognosis in patients with the mucinous as compared with non-mucinous carcinomas. Mucinous carcinomas of all types typically show high signal intensity on T2-weighted MR images, and therefore mimic other conditions such as necrotic tumors, fluid collections, cysts, or liver hemangiomas. To familiarize readers with the MRI appearance, and to avoid pitfalls, this paper illustrates the MRI features of the mucinous adenocarcinomas in various pelvic organs.

Free MRA of the abdomen: postprocessing dynamic gadolinium-enhanced 3D axial MR images.

Dynamic contrast-enhanced whole-abdomen axial images were obtained by using a fat-suppressed, three-dimensional, breath-hold enhanced fast spoiled gradient-echo technique, configured for optimal evaluation for detection and characterization of liver lesions. We then evaluated the feasibility of using these images to reconstruct "free" abdominal magnetic resonance angiography, without additional cost or acquisition time, in 32 randomly chosen patients. The aorta, celiac trunk, superior mesenteric, hepatic, splenic, and renal arteries were clearly depicted.

Endometrial polyps: MR imaging features and distinction from endometrial carcinoma.

PURPOSE: To determine the magnetic resonance (MR) imaging characteristics of endometrial polyps and the accuracy of MR imaging in distinguishing endometrial polyps from endometrial carcinomas in a case-control study. MATERIALS AND METHODS: Cross-referencing pathology records with MR studies from two institutions disclosed 35 patients with surgically proved endometrial polyp or carcinoma after controlling for tumor size. All MR examinations were performed at 1.5 T with T2-weighted fast spin-echo sequences in multiple planes. Three independent readers blinded to histologic diagnoses and clinical data scored each image for the presence of several defined findings. RESULTS: A central fibrous core (low signal intensity on T2-weighted images) and intratumoral cysts (high signal intensity on T2-weighted images) were seen more frequently in endometrial polyps than in carcinomas; myometrial invasion and necrosis showed high predictive value for carcinomas. The readers' responses showed a mean sensitivity of 79%, specificity of 89%, accuracy of 86%, positive predictive value of 82%, and negative predictive value of 88% for diagnosis of carcinoma. The mean area under the receiver operating characteristic curve for the three readers was 0.87 for the diagnosis of carcinoma. CONCLUSION: MR images can help to distinguish most polyps from endometrial carcinomas on the basis of morphologic features. Accuracy does not appear to be sufficient to obviate biopsy, partly because carcinomas and polyps frequently coexist.

Biliary dilatation: differentiation of benign from malignant causes--value of adding conventional MR imaging to MR cholangiopancreatography.

PURPOSE: To determine the value of conventional T1 - and T2-weighted images and gadolinium-enhanced dynamic magnetic resonance (MR) images as a supplement to MR cholangiopancreatographic (MRCP) images in differentiation of benign from malignant causes of biliary dilatation. MATERIALS AND METHODS: MR studies in 62 patients with biliary dilatation with proved causes included conventional T1- and less heavily T2-weighted images, as well as gadolinium-enhanced dynamic images and heavily T2-weighted MRCP images. Two radiologists reviewed MRCP images alone, MRCP images with nonenhanced T1 - and T2-weighted MR images, and MRCP images with nonenhanced and gadolinium-enhanced dynamic images. RESULTS: For differentiation of benign from malignant causes of biliary dilatation, the area under the receiver operating characteristic curve (A(z)) was significantly (P < .05) larger for MRCP images interpreted with T1 - and T2-weighted images (0.9547 for reader 1, 0.8404 for reader 2) than for MRCP images alone (0.8144 for reader 1, 0.8122 for reader 2). The addition of gadolinium-enhanced dynamic MR images to MRCP images with nonenhanced T1- and T2-weighted images did not significantly increase accuracy (A(z) = 0.9554 for reader 1 and 0.8650 for reader 2), but the level of confidence was increased in 17%-24% of cases. CONCLUSION: Use of nonenhanced T1- and less heavily T2-weighted images with MRCP images significantly improved the diagnostic accuracy of MR examinations of pancreaticobiliary disease.

Pancreatic changes in primary sclerosing cholangitis: evaluation with MR imaging.

OBJECTIVE: The purpose of this study was to determine the frequency and the spectrum of MR imaging findings of pancreatic abnormalities in patients with primary sclerosing cholangitis. MATERIALS AND METHODS: MR images in 24 patients with primary sclerosing cholangitis were retrospectively reviewed for evidence of pancreatic abnormalities, including abnormalities of signal intensity; changes in size and morphology; abnormalities of pancreatic ducts; presence of focal lesions, pseudocysts, and peripancreatic edema or fluid; and contrast-enhancement pattern if dynamic studies were available. RESULTS: Eleven patients with pancreatic abnormalities on MR images (case patients) and 13 patients with normal MR findings of the pancreas (cohort patients) were identified. The most common finding in case patients was increased signal intensity of the pancreas on T2-weighted images (73%), followed by decreased signal intensity on T1-weighted images (55%) and decreased enhancement on arterial-phase contrast-enhanced images (50%). Other findings included marked enlargement of the pancreas (27%), narrowing of pancreatic ducts (27%), and peripancreatic edema or fluid (27%). The mean value of the anteroposterior diameter of the pancreatic head in the case patients was significantly greater than that in the cohort patients (p = .039). The mean signal-intensity ratio on the T2-weighted images was significantly higher in the case patients than in the cohort patients (p = .007). CONCLUSION: Increased signal on T2-weighted images, decreased signal on T1-weighted images, enlargement of the pancreas, and decreased contrast-enhancement were MR findings of pancreatic disease associated with primary sclerosing cholangitis.

Mucinous versus nonmucinous rectal carcinomas: differentiation with MR imaging.

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

Multicenter clinical trial of ultrasmall superparamagnetic iron oxide in the evaluation of mediastinal lymph nodes in patients with primary lung carcinoma.

The purpose of this study was to evaluate the clinical efficacy of ultrasmall superparamagnetic iron oxide particles as a magnetic resonance (MR) contrast agent in differentiating metastatic from benign lymph nodes. Eighteen patients with primary lung malignancy and suspected regional lymph node metastases underwent MR imaging before and after Combidex(R) infusion in a multi-institutional study. All MR sequences were interpreted by one or more board-certified radiologists experienced in imaging thoracic malignancy. Each patient was evaluated for the number and location of lymph nodes, homogeneity of nodal signal, and possible change of MR signal post contrast. All patients underwent resection or sampling of the MR-identified lymph node(s) 1-35 day(s) post contrast MR imaging. In all, 27 lymph nodes or nodal groups were available for histopathologic correlation. Combidex had a sensitivity of 92% and a specificity of 80% in identifying pathologically confirmed metastatic mediastinal lymph nodes. Based on our preliminary data, Combidex MR imaging may provide additional functional information useful in the staging of mediastinal lymph nodes.

Mirizzi syndrome: evaluation by MRI imaging.

We report three cases of Mirizzi syndrome diagnosed by MR imaging. MR cholangiography revealed dilation of the intrahepatic bile ducts, narrowing of the common hepatic duct, the level of obstruction, and the location of gallstone in the cystic duct. MR showed thickening of the gallbladder wall and the pattern of wall enhancement. MR evaluation with MR cholangiography sequences proved to be useful in these patients with Mirizzi syndrome.

Uterine leiomyomas: histopathologic features, MR imaging findings, differential diagnosis, and treatment.

Leiomyomas are the most common uterine neoplasm and are composed of smooth muscle with varying amounts of fibrous connective tissue. As leiomyomas enlarge, they may outgrow their blood supply, resulting in various types of degeneration: hyaline or myxoid degeneration, calcification, cystic degeneration, and red degeneration. Leiomyomas are classified as submucosal, intramural, or subserosal; the latter may become pedunculated and simulate ovarian neoplasms. Although most leiomyomas are asymptomatic, patients may present with abnormal uterine bleeding, pressure on adjacent organs, pain, infertility, or a palpable abdominalpelvic mass. Magnetic resonance (MR) imaging is the most accurate imaging technique for detection and localization of leiomyomas. On T2-weighted images, nondegenerated leiomyomas appear as well-circumscribed masses of decreased signal intensity; however, cellular leiomyomas can have relatively higher signal intensity on T2-weighted images and demonstrate enhancement on contrast material-enhanced images. Degenerated leiomyomas have variable appearances on T2-weighted images and contrast-enhanced images. The differential diagnosis of leiomyomas includes adenomyosis, solid adnexal mass, focal myometrial contraction, and uterine leiomyosarcoma. For patients with symptoms, medical or surgical treatment may be indicated. MR imaging also has a role in treatment of leiomyomas by assisting in surgical planning and monitoring the response to medical therapy.

Ultrafast MR imaging of the pelvis.

MR gradient systems with higher slew rates and gradient amplitude enable certain forms of imaging that are not practical with older gradient systems. These newer pulse sequences include single shot half-Fourier T2-weighted images and echo planar imaging. More important in MR imaging of the pelvis, these gradient systems benefit more conventional imaging methods such as gadolinium-enhanced 3D MR angiography, dynamic gradient echo contrast-enhanced images, and T2-weighted fast spin echo images, by shortening echo times. For most MR imaging of the pelvis, spatial resolution is paramount, and therefore sequences such as half-Fourier acquisition Turbo spin echo (HASTE) and 3D gadolinium-enhanced dynamic imaging play a less important role than in the upper abdomen. The potential of these techniques for diffusion or perfusion studies in the pelvis has not been explored.