MR imaging of intraspinal extension of neuroblastoma

The CT and magnetic resonance (MR) findings in two children with intraspinal extension of mediastinal neuroblastoma are described. The potential of MR to obviate the need for myelography is discussed.     

Juvenile fibromatosis of the posterior mediastinum with intraspinal extension.

Chest radiography, CT, and MR imaging were performed in a 3-year-old girl who had posterior mediastinal fibromatosis with transforaminal intraspinal and chest wall extension. Chest radiographs and CT scans showed a slow-growing, noncalcified but locally aggressive left paravertebral mass. The mass was slightly hyperintense relative to muscle on both T1-weighted and fast spin-echo T2-weighted MR images.     

MR imaging of white matter disease in children

Twenty-three pediatric patients with white matter abnormalities on MR images were evaluated retrospectively to assess the contribution of MR compared with CT in diagnosing these conditions. In addition, the MR findings in major categories of white matter diseases were analyzed for sensitivity in detecting the presence of an abnormality. White matter disease categories included demyelinating disease (five cases), dysmyelinating disease (eight cases), developmental white matter abnormalities (four cases), and white matter abnormalities of unknown origin (idiopathic) (six cases), as seen on long TR images. We found that MR is not more sensitive than CT in detecting disease in the demyelinating or dysmyelinating categories, although it is more sensitive than CT in detecting the degree of disease present. In cases of developmental delay, MR is distinctly more useful than CT in demonstrating abnormalities of myelination. And in the idiopathic group, MR detected the presence of focal white matter abnormalities on long TR images in children with neurologic complaints and normal CT. MR may serve to redefine and broaden the spectrum of reported imaging abnormalities in pediatric patients.     

CT and MR imaging in staging non-small cell bronchogenic carcinoma: report of the Radiologic Diagnostic Oncology Group.

The accuracies of magnetic resonance (MR) imaging and computed tomography (CT) in determining tumor classification and assessing mediastinal node metastases were compared in a prospective cooperative study of 170 patients with non-small cell bronchogenic carcinoma. The sensitivity of CT in distinguishing T3-T4 tumors from T0-T2 tumors was 63%; specificity was 84%. These values for MR imaging were not significantly different (56% and 80%). With receiver operating characteristic (ROC) analysis, no difference existed between the accuracies of CT and MR imaging in diagnosis of bronchial involvement or chest wall invasion, but MR imaging was significantly more accurate than CT (P = .047) in diagnosis of mediastinal invasion. Lymph node sampling was performed in 155 patients (642 node stations). Cancerous nodes were found in 14% of stations in 21% of patients. There was no significant difference between the accuracies of CT and MR imaging in detecting mediastinal node metastases (N2 or N3); the sensitivities were 52% and 48%, respectively, and specificities were 69% and 64%. ROC analysis also showed no difference between CT and MR imaging.     

Angeborene Fehlbildungen der Aorta im Kindes- und Jugendalter

Aortic abnormalities are common cardiovascular malformations accounting for 15-20% of all congenital heart disease. Ultrafast CT and MR imaging are noninvasive, accurate and robust techniques that can be used in the diagnosis of aortic malformations. While their sensitivity in detecting vascular abnormalities seems to be as good as that of conventional catheter angiocardiography, at over 90%, they are superior in the diagnosis of potentially life-threatening complications, such as tracheal, bronchial, or esophageal compression. It has been shown that more than 80% of small children with aortic abnormalities benefit directly from the use of noninvasive imaging: either cardiac catheterization is no longer necessary or radiation doses and periods of general anesthesia for interventional catheterization procedures can be much reduced.The most important congenital abnormalities of the aorta in children and adolescents are presented with reference to examples, and the value of CT and MR angiography is documented.     

CT and MR imaging of mediastinal hemangiomas

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

Evaluation of pleural disease using MR and CT. With special reference to malignant pleural mesothelioma

Purpose: To evaluate MR imaging and CT in differentiating malignant pleural mesothelioma from other malignancies or benign pleural disease.Material and Methods: Thirty-four patients (18 pleural mesotheliomas, 9 other malignancies, 7 benign pleural diseases) were examined using enhanced CT and MR. Two radiologists reviewed the CT and two others the MR images. Comparisons were made between the diagnostic groups and the imaging methods.Results: The abnormalities commonly found in malignant disease, but significantly less frequently in benign pleural disease, were focal thickening and enhancement of interlobar fissures. In mesothelioma, enhancement of interlobar fissures, tumour invasion of the diaphragm, mediastinal soft tissue or chest wall, were significantly more often observed than in other malignancies and MR was the most sensitive method. In other malignancies, invasion of bony structures was a more common finding and was also better shown by MR. The contrast-enhanced T1 fat-suppressed (CET1fs) sequence detected these features better than other MR sequences.Conclusion: MR, especially the CET1fs sequence in three planes, gave more information than enhanced CT. Focal thickening and enhancement of interlobar fissures were early abnormalities indicating malignant pleural disease. MR could be clinically useful for differentiating mesothelioma from other pleural diseases.     

Bronchogenic carcinoma: staging with MR compared with staging with CT and surgery

Thirty-three patients suspected of having bronchogenic carcinoma were studied prospectively using magnetic resonance (MR). In this group, 30 underwent examination with computed tomography (CT), 15 underwent thoracotomy, six had mediastinal biopsy procedures performed, and eight underwent bronchoscopy. MR studies, which included transaxial spin-echo imaging (TR, 0.5 and 2.0 sec; TE, 28 and 56 msec) of all patients and sagittal or coronal imaging of 18, were performed without knowledge of CT findings, using only plain radiographs as a guide. CT and MR studies were interpreted separately. CT and MR provided comparable information regarding the presence and size of mediastinal lymph nodes. MR better discriminated mediastinal nodes from vascular structures. However, in two of 11 patients who had multiple mediastinal lymph nodes that were normal in size at CT examination and surgery, MR suggested a confluent abnormal mass, probably because of its poorer spatial resolution. MR was superior to CT in showing enlarged hilar lymph nodes, but CT was better for demonstrating bronchial abnormalities. In three of four patients who had a proved hilar mass with distal obstructive pneumonia, MR (TR, 2.0 sec) helped distinguish between the mass and collapsed lung.     

Magnetic resonance imaging of the hila and mediastinum

In the diagnosis of chest diseases, MR imaging has been shown to be most helpful in the evaluation of hilar and mediastinal lesions. The detection of intrathoracic abnormalities is technique-dependent, and imaging with both short and long repetition and echo times is necessary. ECG gating and sagittal or coronal images supplement transaxial scans in some patients. MR allows the diagnosis of mediastinal vascular lesions and the differentiation of mediastinal mass and vessel without contrast agents. It provides diagnostic information quite similar to that of CT in patients with mediastinal mass, but spatial resolution is somewhat poorer. In patients with hilar mass, MR is superior to CT in identifying the mass and distinguishing it from normal structures.     

Masses of the anterior mediastinum: CT and MR imaging

CT and MR imaging allow earlier diagnosis and more specific characterization of anterior mediastinal masses than is possible with plain film radiographs. This review describes state-of-the-art CT and MR imaging of the anterior mediastinum. After a discussion of CT and MR imaging and indications for their use, normal and abnormal CT and MR findings in the anterior mediastinum are reviewed. Abnormalities include benign and malignant neoplasms, cysts, and mediastinal thyroid. Several masses such as thymolipomas, goiters, cysts, and lymphangiomas often do not require removal and now can be diagnosed with reasonable accuracy when imaging results are combined with clinical history. Detection, diagnosis, staging, and follow-up of malignant anterior mediastinal masses are important and have been improved with CT and MR imaging.     

Initial experience with FSE STIR whole-body MR imaging for staging lymphoma in children

Our objective was to compare fast spin-echo (FSE) short inversion time inversion recovery (STIR) whole-body MR imaging with standard procedures in staging children with lymphoma. Eight children (age range, 2–16 years) underwent multi-station FSE STIR whole-body MR at initial staging (n=5) or for restaging following completion of therapy (n=5). Whole-body MR and conventional staging procedures, including CT (n=10), gallium-67 scintigraphy (n=9), bone scintigraphy (n=3) and bone marrow biopsy (n=7) were retrospectively compared for detection of sites involved by lymphoma and for the assigned stage. FSE STIR whole-body MR detected more sites of possible lymphomatous involvement at initial staging (87/88) and at restaging (5/5) than did conventional imaging (74/88, 3/5). MR was more sensitive than conventional imaging in detecting bone marrow involvement at initial staging. Following treatment, however, residual and therapy-induced bone marrow signal abnormalities could not be differentiated from lymphomatous involvement. Detection of nodal and visceral involvement correlated well. Our results suggest that FSE STIR whole-body MR imaging is a sensitive technique for evaluating lymphomatous involvement of bone marrow as well as non-marrow sites. Larger prospective trials are needed to determine if FSE STIR whole-body MR can replace standard radiographic procedures for initial staging and contribute in the follow-up of lymphoma in children.     

Comparative analysis of MR imaging, positron emission tomography, and ictal single-photon emission CT in patients with neocortical epilepsy

BACKGROUND AND PURPOSE: MR imaging, positron emission tomography (PET), and single-photon emission CT (SPECT) play important roles in presurgical localization of epileptic foci. However, comparative study of these imaging methods for cases of neocortical epilepsy has been limited. The purpose of this study was to compare the sensitivities of these three imaging methods for presurgical localization of neocortical epileptogenic foci. METHODS: We studied 117 consecutive patients who underwent surgery for intractable neocortical epilepsy. The pathologic substrates were neuronal migration disorder (n = 77), tumor (n = 15), and others (n = 25). MR imaging was compared retrospectively with (18)F-fluorodeoxyglucose PET and ictal technetium-99m hexamethylpropyleneamine oxime SPECT regarding their capability to correctly localize the epileptogenic foci. The pathologic findings were used as the standard of reference. RESULTS: Overall, MR imaging, PET, and ictal SPECT correctly localized the lesions for 59.8%, 77.7%, and 70.3% of the patients, respectively, with a 38% concordance rate among the three methods. PET was most sensitive (71-100%) in detecting all substrates. MR imaging was as sensitive (100%) as PET in detecting tumor but was least sensitive (48.1%) in detecting neuronal migration disorder. Ictal SPECT was more sensitive (75.8%) than MR imaging in detecting neuronal migration disorder. Patients with imaging abnormalities achieved good outcomes in 81.4% of the cases, in contrast to 59.5% for those without imaging abnormalities (P <.05). CONCLUSION: PET and ictal SPECT were overall more sensitive than was MR imaging, despite the low concordance rate and variable sensitivity depending on substrates. The detection of abnormalities by MR imaging was associated with good outcome. PET or ictal SPECT can be well used as complementary tools, particularly in cases of negative MR imaging findings.     

0.6 T magnetic resonance imaging of the orbit

Magnetic resonance (MR) imaging of the orbit was performed with a 0.6 T superconducting imaging system in 100 patients with normal orbits who were being evaluated for brain pathology and in 21 additional patients with a variety of orbital lesions to determine the efficacy of MR imaging in displaying orbital abnormalities. Usually, MR studies were performed using a multislice technique with multiple spin-echo pulse sequences and 30, 60, and 90 msec echo times and 500, 1500, and 2000 msec repetition times. Using section thicknesses of about 8 mm, imaging was performed in the transaxial, coronal, and sagittal projections. Pixel size was 0.9 X 1.8 mm, and the examination took about 30 min. The MR findings were compared with computed tomographic (CT) findings in all cases. Either combined axial and coronal studies of 5-mm-thick sections or a thin axial study of 1-mm-thick sections followed by reformatting techniques to obtain multiplanar images was used. Contrast enhancement was used in the CT studies. Both MR and CT clearly demonstrated the soft-tissue abnormality in all cases except two, in which MR failed to detect the abnormality. In one, MR failed to detect a small retrobulbar hemorrhage that occurred after a surgical procedure for retinal detachment. In the second case, rather extensive calcification in the posterior choroidal layers and lens was not detected by MR imaging. In several other cases, MR provided information beyond that obtained with CT. MR has the advantage of providing exquisite anatomic detail in multiplanar images, and it appears to be more sensitive than CT in detecting small, subacute and chronic hemorrhage within soft-tissue masses in the orbit and in detecting ischemia of the globe. CT is superior to MR imaging in portraying fine bone detail.     

Advanced carcinoma of the thoracic esophagus: CT, MR, and echo-endoscopy in the staging after chemotherapy]

Thirteen patients affected with advanced epidermoid carcinoma of the thoracic esophagus were examined by means of CT, MR and endoscopic US (EUS) before and after chemotherapy. Eleven patients underwent esophagectomy and esophagogastroplasty. An intraesophageal prosthesis was positioned in 2 patients since chemotherapy had not modified tumour stage. Post-chemotherapy CT, MR and EUS parameters were compared with the corresponding pathologic findings. As for MR imaging, post-chemotherapy signal intensity variations in T1 and T2 sequences were also evaluated. MR imaging was more accurate than CT in depicting the involvement of mediastinal fatty layers, the relationships between mass and cardiovascular structures, and the cellularity. CT and MR exhibited limitations in identifying metastatic mediastinal lymph nodes, in which case EUS proved to be the most accurate technique. Both CT and MR failed to satisfactorily assess the infiltration of tracheobronchial tree, which was best demonstrated by endoscopy.     

CT and MR of the temporomandibular joint: comparison with autopsy specimens

CT and MR imaging have been advocated for use in the diagnosis of disorders of the temporomandibular joint. A systematic comparison of these imaging techniques has not been made. We performed direct sagittal CT and sagittal MR on 15 fresh temporomandibular joint autopsy specimens and compared our diagnoses with cryosectional findings in a blinded fashion. We found no statistically significant differences between these procedures in detecting bony abnormalities or disk position. However, a side-by-side comparison between the CT and MR images demonstrated that MR depicted the soft-tissue anatomy of the joint with greater detail than did CT. Thus, MR clearly displayed the disk when it was positioned either superiorly or anteriorly, whereas CT only showed the disk adequately when it was positioned anteriorly. MR further showed the configuration of the disk and the borderlines between the disk and its attachments; these relationships could not be assessed from CT images. This experimental study indicates that MR is superior to CT for depiction of soft-tissue changes, whereas CT is superior in showing osseous abnormalities. Clinical confirmation of these results is necessary before one method can be definitively recommended over the other for clinical studies.     

Imaging of central nervous system tumors

Magnetic resonance imaging has been used increasingly in the staging and evaluation of neoplasia of the brain and leptomeninges. In the classification of gliomas, the MR accuracy rate approaches that of pathologic diagnosis. Contrast-enhanced MR imaging has improved specificity in evaluating brain tumors in children and is now the preferred modality for evaluating leptomeningeal metastases of the brain and spine. MR imaging in children has also increased the specificity of histologic diagnosis in hypothalamic hamartoma and juvenile pilocytic astrocytoma. Gadolinium enhancement is most useful in patients older than 35 years of age who have focal neurologic complaints and certain disease histories. The expense of gadolinium contrast material is the major drawback to its routine use. In patients with seizure disorder, MR imaging is more sensitive than CT for detecting abnormalities such as mesial temporal sclerosis, tumors, and vascular malformations. Gadolinium enhancement may be useful in differentiating tumors from mesial temporal sclerosis. Recent reports on the use of MR spectroscopy for evaluating brain metabolism and tumors demonstrate that differences in metabolites exist. A correlation was found in epidermoid tumors between high signal on T1-weighted images and high lipid content, and several studies have shown a positive correlation between glioma grade and glycolytic activity as determined on 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography.     

Extranodal Hodgkin disease: spectrum of disease.

Extranodal lesions in Hodgkin disease may develop and spread to virtually any organ system, simulating other neoplastic or infectious diseases. It is important to determine whether extranodal involvement represents a primary manifestation or dissemination of systemic disease, which has a poorer prognosis. Computed tomography (CT) is the preferred modality, although ultrasonography and magnetic resonance (MR) imaging may also be helpful. CT is superior to conventional radiography in assessing chest disease, although MR imaging is more sensitive than CT in detecting chest wall involvement. CT is preferred for evaluating hepatic lymphoma and has proved particularly valuable in diagnosing gastric lymphoma and detecting renal or perirenal masses. CT and MR imaging are equally effective in detecting brain Hodgkin disease; however, the latter is superior in the detection of extracerebral tumor deposits in the subdural or epidural space. MR imaging is also preferred for evaluating meningeal and spinal cord involvement. Both MR imaging and CT allow excellent assessment of bone texture and accurate analysis of tumoral bone invasion, but MR imaging is superior in demonstrating bone marrow infiltration, and CT is superior in delineating the extent of cortical bone destruction. In the future, metabolic positron emission tomography may provide more information about extranodal lymphoma than do the current imaging modalities.     

MR evaluation of spinal dermal sinus tracts in children

The MR studies of seven pediatric patients with surgically proved spinal dorsal dermal sinuses were reviewed retrospectively. Five of the seven had associated congenital tumors (three epidermoids, two dermoids). The subcutaneous portions of the spinal tracts and intramedullary portions of tumor were easily identified with the use of standard spin-echo techniques. However, except for limited areas where they were lined by fat, the intraspinal portions of the dermal sinuses were poorly seen. Moreover, diffuse subarachnoid tumor was missed in two patients. Three-dimensional Fourier transform gradient-echo acquisition using a volumetric radiofrequency pulse as a "spoiler" proved to be helpful in evaluating these abnormalities. Optimal radiologic workup of patients with dorsal dermal sinuses awaits the development of new MR imaging sequences. For now, heavily T1-weighted MR sequences should be obtained and supplemented with sonography in infants and with CT myelography in older children.     

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.     

CT and MR imaging of the pediatric orbit.

Orbital abnormalities encountered in the pediatric population differ substantially from those found in adult patients. Retinoblastoma, the most serious intraocular tumor, is often difficult to diagnose, but use of computed tomography (CT) (which reveals the characteristic focal calcification) and magnetic resonance (MR) imaging allows this tumor to be differentiated from pseudogliomas, such as Coats disease, and retrolental fibroplasia. CT and MR imaging help in the differentiation of orbital cellulitis from preseptal, lacrimal, and eyelid infectious processes and of orbital pseudotumor from Graves disease. In cases of orbital trauma, CT is excellent for detecting orbital fractures and metallic foreign bodies; MR imaging is better for depicting ocular and optic nerve injuries. Both modalities allow the differentiation of rhabdomyosarcoma from dermoid, cavernous hemangioma, and lymphangioma and provide helpful information for the diagnosis of many other tumors. Since CT and MR imaging have widely expanded the capabilities of orbital imaging, it is more important than ever before for radiologists to understand pediatric orbital disease.