MR imaging of osteogenic and Ewing's sarcoma

Twenty patients with biopsy-proven osteogenic (11 cases) or Ewing's (nine cases) sarcoma were evaluated by MR imaging on a 0.15-T resistive unit to determine the value of MR in the diagnosis and treatment of these two neoplasms and to develop the best protocol for MR imaging. In all 20 cases, MR identified tumor spread into bone marrow, and it was superior to CT in five cases. Extension of tumor into the soft tissues adjacent to bone was shown better by MR than CT in six cases. Improved anatomic information from MR is the result of the ability to image in the axial, coronal, and sagittal planes. Compared with CT, MR identifies cortical disease but has inferior spatial resolution and defines calcium poorly. MR can be used to monitor tumor response to chemotherapy, and the relationship of tumor to adjacent vasculature can be determined without the use of contrast agents. Two pulse sequences are necessary for maximum display of disease, since, in general, tumor involvement of the bone marrow is best assessed on T1-weighted sequences, and tumor involvement of the soft tissue is best seen on T2-weighted sequences. Additional information about bone-marrow involvement, soft-tissue tumor extent, and the relationship of tumor to blood vessels makes MR a valuable adjunct to CT in the evaluation of these neoplasms.     

Surface-coil MR imaging of orbital neoplasms

Fifteen patients with orbital neoplasms demonstrated by CT were studied with magnetic resonance (MR) using a 13 cm surface coil and a 0.6 T superconducting magnet. The use of a surface coil allowed for a reduction in slice thickness and a significant improvement in spatial resolution resulting in better demonstration and improved characterization of orbital lesions. All neoplasms (15/15) were demonstrated by MR. The lesions were grouped into four main categories on the basis of signal intensities on T1- and T2-weighted images. CT was superior to MR in displaying densely calcified or bony lesions (two of 15 cases). MR was at least equal or superior to CT in demonstrating the other lesions (13 of 15 cases) and had the added advantage of improved tissue characterization in some cases. With the use of surface coils, MR could become the primary imaging technique for evaluation of orbital neoplasms.     

MR imaging of primary bone and soft tissue tumors

MR imaging of 131 cases with pathologically confirmed primary bone and soft tissue tumors were studied. They included 44 bone tumors (25 benign tumors, 19 malignant tumors) and 87 soft tissue tumors (55 benign tumors, 32 malignant tumors). MR imaging was performed on 0.5T, superconductive magnet system. All tumors were evaluated with T1-weighted, T2-weighted and STIR images. In some cases, contrast enhanced MR imaging with Gd-DTPA was applied. MR imaging was proving to be a valuable technique in the evaluation of patients with primary bone and soft tissue tumors. MR imaging was superior to the other modalities in delineating the extent of the tumor and their relation to surrounding structures in all cases. However, plain radiography and CT were more useful for evaluation of calcification, ossification, cortical destruction and endosteal/periosteal reaction than MR imaging. Direct sagittal and coronal images from MR imaging added accurate assessment for the relation between the tumor and their adjacent structures. MR imaging was of limited value in distinguishing benign from malignant tumors with the demonstration of tumor structures only, especially soft tissue tumors. But in bone and soft tissue tumors which have specific morphologic features and intensity patterns, MR imaging was very useful for diagnosis.     

Surface coil MR of spinal trauma: preliminary experience

Nineteen fractured vertebral bodies involving the spine from C1 to L2 in 14 patients were imaged with a 0.6-T magnet using prototypical surface coils. Ten of these patients were studied within the first week of trauma. CT and plain films are superior to MR in detecting fractures and identifying the origin of displaced fragments in cases of extensive comminution. However, all body fractures and most posterior element fractures in the thoracolumbar spine were visible on MR. Fractures involving the cervical neural arch were difficult to detect on transverse section without CT correlation. Our results indicate that MR can probably replace CT in the thoracolumbar region. MR is superior to CT in demonstrating ligamentous injury and trauma to the disk. Unlike CT, MR shows the relation of the thecal sac and spinal cord to retropulsed fragments and epidural hematoma. MR also visualizes cord parenchyma; two cases of cord hemorrhage were not seen on CT. Even at this early stage of development, surface coil MR promises to become important in the evaluation of spinal trauma, not only in assessing the integrity of the spinal canal and cord, but in separating stable from unstable fractures on the basis of disruption of the posterior ligaments and elements. Additionally, the demonstration of rupture of specific ligaments may have an impact on surgical management.     

MR imaging in the diagnosis of pancreatic disease

MR imaging examinations of 20 patients with normal pancreas and of 38 patients with suspected pancreatic disease were analyzed retrospectively to evaluate the ability of MR imaging to depict the normal and abnormal pancreas, establish MR criteria for various pancreatic diseases, determine if MR imaging can distinguish among various pancreatic diseases, and compare the usefulness of MR imaging with CT. In all 20 patients with normal pancreas and in 34 of the 38 patients with suspected pancreatic disease excellent or good evaluation of the pancreas was achieved. A 0.35-T magnet (Diasonics MT/S) was used, and both T1- and T2-weighted images were needed. T1 and T2 relaxation times and MR signal intensities showed no specific pattern to allow consistent differentiation between normal and diseased pancreatic tissue or to distinguish between tumor and inflammation. In the 29 patients in whom MR and CT images could be compared, MR imaging and CT provided equivalent information in 20 (69%). In 4 patients (14%), MR imaging added information, and in 5 patients (17%) of cases, MR imaging yielded less information than CT. MR imaging of the pancreas was found to be superior to CT in selected instances, such as in the staging of pancreatic neoplasms (n = 4) and in the evaluation of pancreatic disease after surgery (n = 3). We conclude that, at present, MR imaging should not be used as the screening method for pancreatic disease but should be reserved as an adjunct when the information provided by CT is insufficient.     

The role of MR and CT in evaluating clival chordomas and chondrosarcomas

Sixteen chordomas and nine chondrosarcomas of the clivus were evaluated with CT and MR either before (22 cases) or after (three cases) treatment with proton beam irradiation. The ability of these imaging techniques to provide information necessary to direct patient treatment was studied. The tumor was detected and its gross margins were identified by both techniques in all instances. No reliable diagnostic features allowing differentiation between these two tumors were encountered. MR generally was superior in defining the exact position of the brainstem and optic chiasm relative to the tumor, and it frequently provided superior information about tumor extension into the nasopharynx and cavernous sinus. CT was always better than MR in demonstrating tumoral calcification and in defining the exact anatomy of bone destruction. MR was generally superior to CT in demonstrating the position of the cavernous internal carotid artery relative to the tumor and often provided superior visualization of the vertebral and basilar arteries. In cases in which bone-induced artifact obscured the interface between the neural axis and tumor in the CT image, or in which the tumor had suprasellar extension and was likely to compress the optic chiasm and tracts, MR was of great value in planning irradiation therapy. The high occurrence of clinically asymptomatic signal intensity alterations in the MR studies of previously treated patients appears to limit the differential diagnostic value of this information. Given its greater availability and lower cost, CT appears to be the technique of choice for routine follow-up of previously treated patients.     

MR of craniopharyngiomas: tumor delineation and characterization

MR imaging and CT (with and without contrast enhancement) were performed in 20 patients with an established or clinically suspected diagnosis of craniopharyngioma. Fifteen had biopsy-proven craniopharyngioma and five had presumed craniopharyngioma based on clinical and CT findings. In two cases MR was superior to contrast-enhanced CT in demonstrating the tumor. A variable appearance on T1-weighted MR images reflected the pathologic appearance of craniopharyngiomas. High intensity on T1-weighted images corresponded to high cholesterol content or presence of methemoglobin. MR was the preferred method in the evaluation of tumor extent, especially in the cavernous sinus and posterior clival region. CT was superior to MR in detecting the presence of calcification, which with the clinical history correctly suggested the diagnosis of craniopharyngioma. Both MR and CT studies are desired initially to establish the diagnosis and to evaluate tumor extent. MR was the preferred method in detecting the presence of recurrent tumor.     

Tumors of the nasopharynx and adjacent areas: MR imaging with Gd-DTPA

The purpose of this study was to describe our experience with Gd-DTPA-enhanced MR imaging in the evaluation of the most common nasopharyngeal tumors. Forty-two patients with tumors of the nasopharynx and adjacent spaces had MR imaging before and after IV injection of Gd-DTPA. Images were obtained with a 1.0-T superconducting magnet imaging system in transverse, coronal, and sagittal planes with T1- and T2-weighted sequences. MR images were compared with CT scans and tumor histology. The studies were categorized by using a grading system with grades ranging from unsatisfactory (grade 0) to optimal (grade 3). Contrast-enhanced MR enables better identification of small anatomic details such as both palatini muscles and the pharyngobasilar fascia. MR after Gd-DTPA was superior to CT in all cases except for tumors of the maxillary sinuses. MR with Gd-DTPA is recommended for tumors that are small and difficult to detect on the initial nonenhanced MR examination or that show subtle infiltrations. Because of the increased cost and longer examination time, MR with Gd-DTPA does not need to be done when large tumors are well delineated.     

Comparison of CT and MR imaging in musculoskeletal neoplasms

Magnetic resonance (MR) and CT of 50 musculoskeletal neoplasms were compared to investigate the relative values of these modalities in the assessment and staging of musculoskeletal neoplasms and to determine how often they are complementary and when they are redundant. The material included 25 benign and 25 malignant neoplasms, of which 33 were skeletal and 17 were of soft tissue origin. Magnetic resonance was superior to CT with respect to all morphologic criteria except for cortical bone destruction, calcification, ossification, and the assessment of lytic and sclerotic changes in flat bones. Magnetic resonance was found to be complementary to CT in 48% of the cases (30% malignant, 18% benign). Use of both MR and CT was considered redundant in 52% of the cases (20% malignant, 32% benign). Magnetic resonance was found to be the modality of choice for all benign and malignant soft-tissue neoplasms. Both modalities are complementary and necessary for complete evaluation of malignant skeletal tumors. Benign skeletal tumors should be considered for evaluation by CT, MR, or both on an individual case basis.     

Tumors of the nasopharynx and adjacent areas: MR imaging with Gd-DTPA

The purpose of this study was to describe our experience with Gd-DTPA-enhanced MR imaging in the evaluation of the most common nasopharyngeal tumors. Forty-two patients with tumors of the nasopharynx and adjacent spaces had MR imaging before and after IV injection of Gd-DTPA. Images were obtained with a 1.0-T superconducting magnet imaging system in transverse, coronal, and sagittal planes with T1- and T2-weighted sequences. MR images were compared with CT scans and tumor histology. The studies were categorized by using a grading system with grades ranging from unsatisfactory (grade 0) to optimal (grade 3). Contrast-enhanced MR enables better identification of small anatomic details such as both palatini muscles and the pharyngobasilar fascia. MR after Gd-DTPA was superior to CT in all cases except for tumors of the maxillary sinuses. MR with Gd-DTPA is recommended for tumors that are small and difficult to detect on the initial nonenhanced MR examination or that show subtle infiltrations. Because of the increased cost and longer examination time, MR with Gd-DTPA does not need to be done when large tumors are well delineated.     

Radiologic staging of primary bone sarcoma: MR imaging, scintigraphy, angiography, and CT correlated with pathologic examination

The relative value of magnetic resonance (MR) imaging, computed tomography (CT), technetium-99m bone scintigraphy, and angiography in local tumor staging was prospectively evaluated in 56 patients with primary bone sarcoma. The results of imaging were correlated with findings at surgery and at dissection of the resected specimens. MR imaging was significantly superior to CT and scintigraphy in defining intraosseous tumor length and was as accurate as CT in demonstrating cortical bone and joint involvement. It was definitely superior to CT in demonstrating involvement of muscle compartments. MR imaging was also the best modality in exhibiting the relationship between tumor and major neurovascular bundles; however, these differences were not significant. It is concluded that MR imaging is the modality of choice for local staging of primary bone sarcoma.     

骨样骨瘤的影像诊断

目的探讨骨样骨瘤的X线、CT与MR表现。方法搜集我院2006—2007年经手术病理证实的骨样骨瘤20例,其中男性12例,女性8例,年龄11~37岁,平均年龄24岁。所有病例均行X线检查,其中行CT检查者6例,行MR检查者8例。分析上述3种影像检查对骨样骨瘤瘤巢的显示率。结果在常规X线检查中20例病灶均表现为一圆形或卵圆形的透亮区,直径>5~16 mm,周围可见不同程度的骨质硬化;其中16例可以看到瘤巢,显示率为80%;6例经CT薄层扫描均可清楚显示瘤巢,显示率为100%;8例行MR检查,其中6例可显示瘤巢,并可见瘤巢周围的软组织肿胀,瘤巢显示率为75%。结论瘤巢是确诊骨样骨瘤的关键。常规X线是诊断骨样骨瘤的首先检查方法,CT是显示瘤巢最可靠的方法,MR显示瘤巢不如CT敏感,但却可以清楚的显示瘤巢周围的软组织肿胀情况。     

Noninvasive evaluation of knee meniscal tears: preliminary comparison of MR imaging and CT

One hundred twenty knees were examined prospectively with both axial computed tomography (CT) and magnetic resonance (MR) imaging to compare the value of these techniques in patients with clinical evidence of meniscal tears. Sixty-four of these knees were subsequently evaluated with diagnostic arthroscopy. In this group, CT was superior to MR imaging for meniscus evaluation in 29.7% of the knees, equal to MR in 54.7%, and inferior to MR in 15.6%. Although surface-coil MR imaging shows great promise and has numerous advantages over more conventional techniques, this preliminary experience suggests that, at least with certain imaging equipment and techniques, CT may be slightly more efficacious than 0.5-T MR imaging in meniscus evaluation. However, further comparative studies at higher field strengths are needed before the relative roles of CT and MR imaging can be established.     

骨原始神经外胚叶肿瘤影像学表现

目的研究骨原始神经外胚叶肿瘤的影像学特点。资料与方法搜集5例骨原始神经外胚叶肿瘤的影像及临床、手术病理资料,分析其影像学表现。结果5例中．胸椎2例,胸壁、股骨、胫骨各1例。1例胸壁病变表现为巨大软组织肿块,并推移周围组织。2例脊椎病变破坏椎管内外骨质及软组织。2例四肢长骨病变呈溶骨性骨质破坏,1例有软组织肿块。5例均未见病变内钙化及局部淋巴结肿大。MRI对显示病变组织成分及侵袭范围较X线和CT好。结论溶骨性骨破坏和巨大软组织肿块是骨原始神经外胚叶肿瘤的常见影像学表现,病灶内钙化和局部淋巴结肿大少见。MR／对显示病变组织成分及侵袭范围较好。本病最终诊断依靠病理和免疫组织化学检查。     

八例Askin瘤的影像诊断

目的研究Askin瘤的影像表现，提高对该病的认识及鉴别诊断能力。方法回顾性分析经病理证实的8例Askin瘤的影像表现。8例均行X线检查，7例行CT检查，1例行MR检查，4例行核素骨扫描。结果8例Askin瘤均表现为位于胸壁或胸腔的软组织肿物，其中左侧4例，右侧4例。6例大病灶密度不均匀，2例较小病灶内密度或信号均匀；CT扫描4例可见囊变、坏死区。CT、MRI、核素骨扫描共显示肋骨破坏6例，其中CT显示4例，MRI显示1例，核素骨扫描显示放射性核素浓集3例。胸腔积液6例。瘤肺交界面清楚1例，不清楚7例。8例病灶中均未见钙化。结论Askin瘤影像学表现为胸腔或胸壁的软组织肿物，但不具有特异性，对发生于儿童及青少年的胸壁肿物，应注意鉴别诊断。     

Thoracic aortic dissections: magnetic resonance imaging

Six patients with documented dissections of the thoracic aorta (two Type A, four Type B) were examined by magnetic resonance (MR) imaging using a 0.6-Tesla superconductive magnet. Cardiac gating was applied in five cases. Correlation was made with CT and angiography. MR imaging demonstrated the dissection in all six cases and accurately differentiated Type A from Type B dissections. Coronal and sagittal MR sections were advantageous in establishing the relationship of the three arch vessels to the dissection. In addition, cardiac-gated MR was useful in demonstrating mural thrombus and in distinguishing the true from the false lumen based on differences in signal intensity resulting from different flow rates. In five cases, the information obtained by MR was equal to or surpassed that obtained by CT. In the one case of a completely thrombosed dissection, the CT scan was more helpful. MR should become an important imaging modality in the evaluation of aortic dissections.     

NMR imaging in temporal lobe epilepsy due to gliomas

Magnetic resonance (MR) imaging has been shown to have greater sensitivity than X-ray CT in a broad range of intracranial pathologic processes. In regions in which CT is likely to suffer degradation of image quality due to a variety of bone artifacts, the advantages of MR are even more striking. Previous reports have emphasized the relative advantages of MR in studies of the posterior fossa. The present report documents the potential for similar advantages of MR in demonstration of middle fossa anatomy and in identification and characterization of temporal lobe lesions. In three patients with anterior temporal lobe gliomas and temporal lobe epilepsy, MR (even with the use of an early prototype, resistive system of 0.15 T) was clearly superior to contrast-enhanced CT in demonstrating the pathology. This considerably assisted preoperative evaluation.     

Comparison of computed tomography and angiography in the evaluation of soft tissue tumors of the extremities

CT and angiography were performed in 21 patients with soft tissue tumors of the extremities (18 malignant and 3 benign) and the results were compared with the surgical and histopathologic findings. The tumor size was correctly evaluated at CT in 15 of 21 cases and at angiography in 17 of 21 cases. The main reason for overestimation of longitudinal tumor extent seems to be edema surrounding the poles of high grade malignant neoplasms. CT was superior to angiography in demonstrating the intra- or extramuscular tumor location. If only factors important for the surgical planning are considered, angiography yielded such information in 8 cases while CT was of critical value in the preoperative evaluation of 14 patients. It is concluded that CT should precede angiography in the examination of soft tissue tumors of the extremities. Angiography may be superior to CT in demonstrating vascular anatomy in relation to tumors of the medial thigh. With other tumor locations, angiography should be reserved for those lesions where vascular relationships are not adequately demonstrated at CT.     

Early diagnosis of spinal metastases by CT and MR studies

Fifteen patients with known metastatic or high-risk primary cancer, normal neurologic examinations, and new abnormalities on 99mTc bone scan were evaluated with spinal CT and magnetic resonance (MR) imaging. Four patients underwent CT metrizamide myelography. Spinal CT and MR agreed in 14 of 15 patients demonstrating spinal metastases in 12 patients and benign disease in two. In one patient spinal CT was normal, but MR showed altered marrow signal consistent with metastatic disease. Epidural tumor was demonstrated by CT metrizamide myelography in four cases, all correctly identified by MR. Further evaluation of spinal MR in this setting is warranted.     

The role of magnetic resonance imaging in giant cell tumor of bone

In six cases of giant cell tumor the magnetic resonance (MR) images obtained with various pulse sequences and field strengths were compared to the corresponding computed tomography (CT) scans and plain roentgenograms. MRI was superior to CT and plain films in demonstrating areas of tissue inhomogeneity within the tumor as well as soft tissue extension. CT was superior in demonstrating cortical thinning. Multiplanar imaging capability and visualization of articular cartilage may demonstrate intra-articular tumor spread. The characteristic MRI findings with short TR/TE (T1-weighting) and long TR/TE (T2-weighting) are described. We also describe one case where serial MR scans were used to assess response to therapy.