Bladder tumor staging: comparison of conventional and gadolinium-enhanced dynamic MR imaging and CT.

With computed tomography (CT) and unenhanced magnetic resonance (MR) imaging, stage pT3b extravesical extension and beyond can be diagnosed, but tumors confined to the bladder wall (stages pT1-pT3a) are poorly delineated. To determine whether visualization of such tumors could be improved with gadolinium-enhanced MR imaging, dynamic breath-hold T1-weighted MR images were obtained after intravenous infusion of 0.1 mmol/kg gadopentetate dimeglumine in 79 patients (86 tumors). Conventional MR images, CT scans, and histologic correlation were available in all cases. With dynamic gadolinium-enhanced MR imaging, the mucosa could be distinguished from the muscular layers of the bladder wall. Staging accuracy with this technique was 85% (73 of 86), which was significantly better than with CT (55%; 47 of 86) (P < .005) or conventional MR imaging (58%; 50 of 86) (P < .05). The accuracy of staging the intramural extent (pT1-pT3a) of bladder tumors was thus improved with gadolinium-enhanced dynamic MR imaging.     

原发性心脏心包肿瘤的MRI诊断分析

目的：分析原发性心脏心包肿瘤的ＭＲＩ所见，评价ＭＲＩ对本病诊断的意义。材料和方法：１４例原发性心脏心包肿瘤均经ＭＲ检查，男９例，女５例。年龄６个月～６４岁，平均４４岁，其中儿童２例。１４例中８例经手术病理证实６例经ＭＲ和超声诊断。所有病例ＭＲ扫描前均有Ｘ线平片检查。结果：１４例心脏心包肿瘤中心腔内肿瘤５例，证实为粘液瘤，４例位于左房，１例位于左室。肌壁肿瘤６例，１例证实为淋巴管瘤。心包肿瘤３例，２例证实为脂肪瘤和间皮肉瘤。结论：ＭＲ对心脏心包肿瘤具有诊断价值，更适于全面观察肿瘤对心肌的浸润和向腔内外扩散及其与心旁肿瘤的鉴别     

CT and MR imaging findings of benign cardiac tumors

This imaging review describes the appearance of benign cardiac tumors on CT and MRI. Although rare, benign tumors outnumber their primary malignant counterparts three to one. Since mortality varies directly with invasion, identifying the neoplasm at an early stage helps focus treatment, especially in benign cases, which generally respond well to surgical resection. In adults and children, myxomas and rhabdomyomas, respectively, represent the most common benign tumors, which can be grouped into tissue-specific subtypes, such as rhabdomyomas, fibromas, lipomas, teratomas, etc. Besides their variable prevalence in particular age groups, these tumors also differ with regard to their gender predilection, location, and number. For example, myxomas appear predominantly in women and generally as a solitary mass in the left or right atrium, whereas rhabdomyomas present equally in boys and girls and chiefly as multiple masses in the ventricles. Despite their differences, however, both types share an association with heritable syndromes like the Carney complex for myxomas and tuberous sclerosis for rhabdomyomas. As with all cardiac tumors, echocardiographic findings usually suggest the initial diagnosis but cross-sectional imaging with CT and MRI can help resolve diagnostically challenging cases. For example, with its direct multiplanar capability, excellent contrast resolution, and large field of view, MRI permits a detailed examination of the entire mediastinum, helping to rule out an equivocal mass on echocardiography. Through dynamic techniques, MRI, in addition to morphologic characterization, can depict the pathophysiological effects of these tumors, for instance, with regard to myocardial contraction, valvular function, or blood flow.     

Detection and staging of renal neoplasms: a reassessment of MR imaging

The use of magnetic resonance (MR) imaging in the detection and staging of renal neoplasms was investigated in 104 patients with 106 renal cell carcinomas confirmed at surgery or autopsy. Overall, MR imaging demonstrated 101 of 106 lesions (95%), including all 93 tumors that were larger than 3 cm in diameter but only eight of the 13 smaller tumors (62%). MR imaging enabled accurate staging of 82% of all detected lesions but led to the understaging of nine lesions and the overstaging of nine. At present, MR imaging cannot be used as a screening modality for renal tumors. However, its negative predictive values of 98% and 99%, respectively, for the evaluation of tumor vascular extension and tumor spread to adjacent structures makes it an excellent staging modality that should be used when the CT findings are equivocal. MR imaging is not accurate in indicating bowel and mesentery involvement, but rapid technical advances and the introduction of bowel contrast medium may improve this present limitation.     

Primary intracardiac tumors in magnetic resonance imaging

Fifteen patients suspected of having 18 intracardiac masses by two-dimensional echocardiography underwent MR imaging. In MR imaging, intracardiac masses were evaluated on both short TE (TE = 20-35 msec) and long TE (TE = 50-80 msec) spin echo sequences, and were differentiated from myocardium or papillary muscle. Three masses were excluded (they were papillary muscle) by MR imaging, and three were additionally found in patients with tuberous sclerosis. Fifteen masses were found by both echocardiography and MR imaging, one of which was stagnant blood. Cine MR imaging was needed to differentiate between thrombus and stagnant blood. MR imaging is useful for the evaluation of intracardiac masses. It is recommended in addition to echocardiography when cardiac tumors are suspected, especially in patients with tuberous sclerosis.     

Intracavitary birdcage resonator: Applications to the human prostate

Twenty-five patients with prostatic cancer were pro- spectively examined with a prototype endorectal surface coil featuring a birdcage resonator circuit design. The purpose was to determine the safety of an intracavitary probe for magnetic resonance (MR) imaging of the pelvis that incorporates the “inside-out” characteristics of a volume coil design and allows high-resolution MR imaging of the prostate and potentially serves as an alternative to single-loop intracavitary surface coils. Clinically useful images supplementing images obtained with the body or external surface coils were obtained with the prototype probe. It was tolerated by all patients enrolled in the study, and none experienced side effects. The cylindrically symmetric sensitivity profile of the probe allowed identification of prostate tumors and pelvic lymph node and bone me-tastases. Volume-type coils may improve endopelvic MR imaging when used alone or in combination with external coil systems.     

Role of MR imaging in the selection of patients with early cervical carcinoma for fertility-preserving surgery: initial experience.

PURPOSE: To assess whether magnetic resonance (MR) imaging can be used for reliable prediction of proximal extension of cervical carcinoma into the myometrium. MATERIALS AND METHODS: Thirty patients with early cervical carcinoma underwent MR imaging with use of a 1.5-T magnet prior to surgery. The MR images were analyzed by two radiologists, unaware of the histopathologic findings, for the relationship of the tumor to the internal os and extension of the tumor into the myometrium. Findings at MR imaging were compared with those at histopathologic examination. RESULTS: At MR imaging, 24 patients were considered not to have tumor extension proximal to the internal os and into the myometrium. All tumors were confirmed histopathologically. In six patients thought to have myometrial tumor invasion at MR imaging, five tumors were confirmed histopathologically; in one, tumor extended up to the internal os but did not involve the myometrium. CONCLUSION: This is a small study, but MR imaging appears accurate in the prediction of myometrial tumor involvement and in showing the relationship of cervical carcinoma to the internal os and, hence, the patient's suitability for trachelectomy.     

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多技术扫描检测活性心肌及其和心肌声学造影对比的临床研究

目的 评价MR多技术扫描和心肌声学造影（MCE）在检测心肌灌注、判断心肌存活中的作用。资料与方法 应用MR多技术扫描对36例冠心病患者进行检查,并将结果与冠状动脉造影、MCE结果对照。结果 共有81支冠状动脉狭窄≥70％,狭窄的冠状动脉供血区域为334个（57．99％）节段。MR心肌灌注扫描见268个（46．53％）节段呈缺血改变,MR心肌活性扫描见83个（14．4l％）节段心肌梗死。以冠状动脉造影结果为标准,MR心肌灌注扫描的敏感性为80．2％,特异性为100％,总符合率为88．5％,Kappa值为0．773。定性MCE检查共有202个（35．07％）节段呈缺血改变。以冠状动脉造影结果为标准,定性MCE的敏感性为60．5％,特异性为100％,总符合率为77．1％,Kappa值为0．563。MR心肌灌注扫描所发现的缺血节段比狭窄冠状动脉的供血节段少但无统计学意义（P=0．468）,MCE所发现的缺血节段比狭窄冠状动脉的供血节段少（P=0．000）;MR心肌灌注扫描检出缺血节段比MCE检出的多（P=0．000）。结论 MR多技术扫描可清晰显示心肌缺血或梗死的位置、程度,可重复性好,与冠状动脉造影结果的一致性较高。MCE为临床提供了元创、可重复地准确测定心肌缺血的新方法,但其评价方法具有一定主观性且低估心肌缺血的范围,检查者的经验和检查方法在一定程度上影响其准确性。     

Soft-tissue sarcomas of the extremities. Their assessment with magnetic resonance

MR imaging was performed on 38 patients with suspected malignant soft-tissue tumors of the extremities. MR diagnostic accuracy was compared with that of other methods. All patients underwent surgical control. In 7 cases MR imaging was employed to demonstrate the tumor response to antiblastic local perfusion. Lesion identification, extension, compartmental evaluation, bone and vascular involvement were the diagnostic parameters considered. In all cases MR imaging detected the lesion, correctly showing the intracompartmental (16 patients) or extracompartmental (22 patients) extension. In 2 out of 6 cases MR imaging did not demonstrate bone invasion, and in 1 case vascular involvement could not be assessed. MR diagnostic accuracy was superior to that of other techniques. Nonetheless, a diagnostic protocol was proposed for the local staging of malignant soft-tissue tumors of the extremities where some diagnostic limitations of MR imaging are taken into account--i.e., inconsistent evaluation of bone and vascular involvement. Plain X-rays and US are the imaging modalities of choice, whereas MR imaging is to be a second-choice diagnostic technique before biopsy. Thus, MR imaging replaces CT, while angiography is to be used in selected cases, where MR imaging is not diagnostic due to vascular involvement.     

Penetrating aortic ulcers: diagnosis with MR imaging

The authors studied seven patients with penetrating aortic ulcers with use of magnetic resonance (MR) imaging. All patients were evaluated for acute chest symptoms, and the presence of aortic ulcers was confirmed by means of angiography in all seven patients. Five patients also underwent computed tomography (CT). Three patients underwent surgical repair of the thoracic aorta. MR findings included intramural hematoma and focal aortic wall ulceration in four patients, focal ulceration in one, focal intramural hematoma in one, and focal intramural hematoma with rupture in one. The diagnosis of intramural hematoma was made by the detection of increased signal intensity on T1- and T2-weighted MR images. MR imaging was superior to angiography in depicting the extent of intramural thrombus, although one ulceration diagnosed at angiography was missed at MR imaging. MR imaging was superior to CT in differentiating acute intramural hematoma from atherosclerotic plaque and chronic intraluminal thrombus, although it did not depict displaced intimal calcification in one patient with extensive intramural hematoma.     

MR imaging of urinary bladder neoplasms

The diagnostic potential of magnetic resonance (MR) imaging at 1.5 T for assessment and staging of urinary bladder tumors was investigated in 10 patients with malignant urinary bladder tumors. All patients underwent complete pathologic staging. The appearance of the urinary bladder tumors and the ability to stage them by means of MR imaging was evaluated morphologically and compared with results obtained with pathologic examination. Magnetic resonance imaging permitted tumor localization in all patients. In nine patients the tumor stage was accurately determined by MR imaging. The smallest tumor detected by MR imaging was 1.5 cm. Both transverse and sagittal imaging planes were found to be essential for accurate assessment of tumor extension. Signal intensity data obtained from both dual and multi spin echo sequences showed that tumor display and depth of infiltration was best seen with a repetition time (TR) of 2,000 ms and an echo time (TE) of 90 ms. Accurate evaluation of perivesical tumor infiltration required a sequence with a TR 800 ms and a TE 30 ms. Data presented here further support the role of MR in staging urinary bladder neoplasms.     

Primary thyroid lymphoma: MR appearance

Magnetic resonance imaging was evaluated in six patients with primary thyroid lymphoma. Five patients had a solitary localized tumor and one had multiple tumors. These masses showed homogeneous iso- or high intensity compared with the uninvolved thyroid tissue on T1-weighted images and homogeneous high intensity on T2-weighted images. Diffuse lobulated goiter with homogeneous intensity was seen in the sixth case, where the differentiation between lymphoma and Hashimoto thyroiditis was impossible. Extrathyroidal tumor extension occurred in two cases and cervical lymphadenopathy in one case. In five of six cases, identification and staging of primary thyroid lymphoma were possible with MR imaging. Magnetic resonance imaging was comparable to CT in the detection of tumors (five cases), extrathyroidal extension (two cases), and cervical lymphadenopathy (one case). In three cases, the pseudocapsule (a low-intensity band forming the border between tumor and thyroid tissue) was detected only by MR imaging. In one case, the discrimination between tumor and uninvolved thyroid gland was clearer on MR imaging than on CT.     

MR imaging of the nasopharynx and floor of the middle cranial fossa. Part II. Malignant tumors

The intracranial extension of tumors of the nasopharynx and related spaces presents a difficult imaging problem. Unlike computed tomography (CT) scans, magnetic resonance (MR) images are not limited by beam-hardening artifacts from bone or dental amalgam. Forty-six patients with malignant tumors of the nasopharynx and related spaces affecting the skull base underwent MR imaging. MR images were obtained with a 0.3-T permanent-magnet imaging system in axial, sagittal, and coronal planes. MR findings were compared with clinical records, plain radiographs, CT scans, and pathologic correlates when available. MR imaging could demonstrate neoplastic invasion of the bone of the floor of the middle cranial fossa and the vital soft-tissue structures related to it as well as or better than CT. Tumor extension was viewed directly as a continuous mass or indirectly by marrow replacement or displacement of normal structures. Specific anatomic routes through which tumors extend from the nasopharynx to the middle cranial fossa were inferred from MR findings.     

Periampullary tumors: high-spatial-resolution MR imaging and histopathologic findings in ampullary region specimens

PURPOSE: To prospectively determine the magnetic resonance (MR) signal intensity characteristics of structures of the ampullary region and to assess the potential use of MR imaging in evaluation of the extent of periampullary tumors in resected specimens. MATERIALS AND METHODS: Twenty-five specimens from the ampullary region obtained in four autopsy cases without periampullary tumors and in 21 patients with periampullary tumors were examined with a 1.5-T MR system and a circular surface coil with 5-inch (12.7-cm) diameter. High-spatial-resolution MR images were obtained with field of view of 100 x 100 mm, matrix of 256 x 256 or 512 x 256, and section thickness of 2 mm. MR imaging findings were compared with histopathologic findings. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of high-spatial-resolution MR imaging for assessment of tumor invasion into surrounding tissues were evaluated by two radiologists. RESULTS: T1- and T2-weighted MR images clearly depicted normal structures in the ampullary region that included Oddi muscle, duodenal wall, common bile duct, and pancreas; these findings corresponded well with histologic findings. In 20 (95%) of 21 tumors, high-spatial-resolution MR imaging depicted location and extension of periampullary tumors precisely. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of high-spatial-resolution MR imaging for assessment of tumor invasion into surrounding tissue were 88%, 100%, 96%, 100%, and 94%, respectively. CONCLUSION: In this study, MR imaging correctly depicted location, extension, and origin of tumor. High-spatial-resolution MR imaging has potential for presurgical staging of tumors in this region.     

Prostate cancer: endorectal MR imaging and MR spectroscopic imaging--distinction of true-positive results from chance-detected lesions

PURPOSE: To retrospectively investigate size criteria for the identification of chance-detected lesions at endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging of prostate cancer. MATERIALS AND METHODS: Approval of the committee on human research and written informed consent were obtained. This study was HIPAA compliant. Endorectal MR imaging and MR spectroscopic imaging were performed with a 1.5-T MR imager in 48 men with a mean age of 59 years (age range, 47-75 years) prior to radical prostatectomy. Two independent readers recorded the size and location of all suspected peripheral zone tumor nodules on MR images alone and on images obtained with combined MR imaging and MR spectroscopic imaging. Nodules detected at MR imaging were classified as matched lesions if tumor was present in the same location at step-section histopathologic review. For all matched lesions, kappa values were calculated to examine agreement between measured and actual tumor size. Lesions that were overmeasured at MR imaging with a kappa value of less than 0.2 were considered chance-detected lesions. RESULTS: At MR imaging, two of 27 and four of 35 matched lesions for readers 1 and 2, respectively, were chance-detected lesions. The corresponding numbers of lesions at combined MR imaging and MR spectroscopic imaging were one of 21 and one of 31, respectively. In all but two cases, the measured diameter of chance-detected lesions was more than twice that of the diameter at histopathologic analysis. By using this diameter threshold to distinguish true-positive results, the mean diameter of detected tumors at histopathologic analysis was 15 mm compared with 4 mm for both undetected and chance-detected tumors (P < .05). CONCLUSION: To ensure uniformity in the comparison of scientific studies, peripheral zone tumors detected at MR imaging and MR spectroscopic imaging of the prostate that are in the same location as tumors detected at histopathologic review should be considered chance-detected lesions if the MR transverse diameter is more than twice the histopathologic transverse diameter.     

Hepatocellular carcinoma: MR imaging

Sixty patients with hepatocellular carcinoma (HCC) were studied with computed tomography (CT) and magnetic resonance (MR) imaging at 1.5 T. MR imaging was equivalent to CT in detection of HCC. MR imaging was superior to CT in demonstrating the details of tumors, especially pseudocapsules. In 58 cases, main tumors were detected with MR imaging. On spin-echo (SE) 600/25 (repetition time msec/echo time msec) sequences, tumors were hyperintense in 18 cases, isointense in ten, and hypointense in 30. On SE 2,000/60 sequences, all but two tumors had high signal intensity. Pseudocapsules, intratumoral septa, daughter nodules, and tumor thrombi, which are important characteristics of HCC, were demonstrated in 22, three, six, and six cases, respectively, on MR imaging. MR imaging is useful for characterizing the internal architecture of HCC.     

Comparison of Echo and MRI in the Imaging Evaluation of Intracardiac Masses

We compared the efficacy of echocardiography (ECHO) and magnetic resonance imaging (MRI) for evaluating intracardiac masses. Over an 8-yr period, 28 patients, 21 males, 7 females, 16 days–60 years of age (mean 25 years) with a suspected intracardiac mass on ECHO (transthoracic in all; transesophageal in 9) underwent an MRI examination. Five patients had a contrast-enhanced MRI. ECHO and MRI were compared with respect to their technical adequacy, ability to detect and suggest the likely etiology of the mass, and provide additional information (masses not seen with the other technique, inflow or outflow obstruction, and intramural component of an intracavitary mass). With MRI, the image morphology (including signal intensity changes on the various sequences) and extracardiac manifestations were also evaluated. The diagnosis was confirmed by histopathology in 18, surgical inspection in 4, by follow- up imaging on conservative management in 5, and by typical extracardiac manifestations of the disease in 1 patient.Fifteen (54%) patients had tumors (benign 12, malignant 3), 5 had a thrombus or hematoma, and 4 each had infective or vascular lesions. Thirty-four masses (13 in ventricle, 11 septal, 7 atrial, 2 on valve and 1 in pulmonary artery) were seen on MRI, 28 of which were detected by ECHO. Transthoracic ECHO (TTE) and MRI were technically optimal in 82% and 100% of cases, respectively. Nine patients needed an additional transesophageal ECHO (TEE). Overall, MRI showed a mass in all patients, whereas ECHO missed it in 2 cases. In cases with a mass on both modalities, MRI detected 4 additional masses not seen on ECHO. MRI suggested the etiology in 21 (75%) cases, while the same was possible with ECHO (TTE and TEE) in 8 (29%) cases. Intramural component, extension into the inflow or outflow, outflow tract obstruction, and associated pericardial or extracardiac masses were better depicted on MRI. We conclude that MRI is advantageous over a combination of TTE and TEE for the detection and complete morphological and functional evaluation (hemodynamic effects) of cardiac masses.     

Primary musculoskeletal tumors: examination with MR imaging compared with conventional modalities

In 176 cases of primary musculo-skeletal tumors, the informative value of magnetic resonance (MR) imaging was compared with that of plain radiographic examination, angiography, scintigraphy, and computed tomography (CT). In all patients the surgical and histopathologic results were known. For bone tumors confined to the bone, MR imaging was excellent for evaluation of intraosseous extent, but it could not be proved significantly better than CT or scintigraphy. MR imaging was inferior to plain radiography and CT for evaluation of calcification, ossification, cortical destruction, and endosteal/periosteal reaction. For soft-tissue tumors and bone tumors with soft-tissue extension, MR imaging was significantly better than the other modalities in all variables examined: delineation between tumor and muscle, tumor and vessel, tumor and fat, tumor and joint, and tumor and bone, as well as depicting intralesional necrosis and bleeding.     

Magnetic resonance imaging of intracranial epidermoids: report of two cases

Intracranial epidermoids are uncommon benign tumors in the subarachnoid spaces. We have studied two patients with these tumors originating in the basal cisterns using magnetic resonance (MR) imaging, computed tomography (CT), and cerebral angiography. Both CT and MR showed the extraaxial position of these tumors and their extension into the posterior fossa well. Angiography did not show any abnormal vasculature but displacement of vessels by the tumor mass was well demonstrated. MR was found to be relatively specific in characterizing these tumors.