Magnetic resonance imaging study on the results of surgery for cervical compression myelopathy

The morphologic changes and signal intensity of the spinal cord on preoperative magnetic resonance images were correlated with postoperative outcomes in 74 patients undergoing decompressive cervical surgery for compressive myelopathy. The transverse area of the spinal cord on T1-weighted images at the level of maximum compression was closely correlated with the severity of myelopathy, duration of disease, and recovery rate as determined by the Japanese Orthopaedic Association score. In patients with ossification of the posterior longitudinal ligament or cervical spondylotic myelopathy, the increased intramedullary T2-weighted magnetic resonance imaging signal at the site of maximal cord compression and duration of disease significantly influenced the rate of recovery. A multiple regression equation was then developed with these three variables to predict surgical outcomes.     

Osteogenic sarcoma: noninvasive in vivo assessment of tumor necrosis with diffusion-weighted MR imaging

PURPOSE: To evaluate diffusion-weighted magnetic resonance (MR) imaging for detecting tumor necrosis in an animal model of osteogenic sarcoma. MATERIALS AND METHODS: Twelve rats with osteogenic sarcoma underwent T1-weighted unenhanced and gadolinium-enhanced spin-echo and diffusion-weighted spin-echo MR imaging. Histologic correlation was performed. Signal intensities, T2 relaxation times, normalized apparent diffusion coefficients, and relative signal intensity increases were calculated. RESULTS: On diffusion-weighted images, necrotic tumor showed low signal intensity (mean normalized apparent diffusion coefficient, 0.46 +/- 0.20 [1 standard deviation]), indicating rapid diffusion of water molecules as a result of loss of membrane integrity, while viable tumor showed high signal intensity (mean normalized apparent diffusion coefficient, 0.16 +/- 0.05; P < .0001). Differences in the T2 relaxation times and relative signal intensity increases between viable and necrotic tumor were not statistically significant. CONCLUSION: Normalized apparent diffusion coefficients are more accurate in differentiating between viable and necrotic tumor than are T2 relaxation times or relative signal intensity increases on contrast-enhanced images. Signal intensity overlap between viable and necrotic tumor on gadolinium-enhanced images may be caused by the small molecular size of the agent, which permeates the interstitial space freely, thereby also enhancing necrosis. Diffusion-weighted MR imaging depicts differences in diffusion and, ultimately, in membrane integrity between viable and necrotic tumor and may be used to monitor tumor viability during treatment.     

Radiation myelopathy: a clinicopathological study with special reference to correlation between MRI findings and neuropathology

We describe magnetic resonance imaging (MRI) and neuropathological findings in a patient with chronic progressive radiation myelopathy (CPRM). An 81-year-old man with esophageal cancer underwent radiotherapy. Four years later he developed a progressive neurological deficit below the irradiated level of the spinal cord. Neurological examination revealed spastic paraplegia. MRI findings showed an area of high signal intensity on T2-weighted images of the thoracic spinal cord. On the basis of clinical and MRI findings, we diagnosed his condition as CPRM. MRI performed thirteen months after onset of neurological signs revealed mild atrophy of the spinal cord detected on T1-weighted images and an area of high signal intensity within the spinal cord detected on T2-weighted images. Neuropathological examination revealed findings consistent with radiation myelopathy. We speculate that the area of high signal intensity within the spinal cord detected on T2-weighted images might be a result of proliferation of small vessels, which was discovered upon autopsy.     

Collision tumors of the adrenal gland: demonstration and characterization at MR imaging

PURPOSE: To evaluate the magnetic resonance (MR) imaging findings in collision tumors of the adrenal gland. MATERIALS AND METHODS: MR images obtained in 104 patients with a known primary malignant tumor and an adrenal mass were reviewed to find adrenal glands that contained two contiguous but histologically distinct masses. The findings in such cases were correlated with histopathologic findings. RESULTS: In two (2%) cases, both MR and histopathologic findings showed a mass within the adrenal gland that consisted of contiguous adrenal adenoma and metastasis, which represented a collision tumor. The adenomatous component in each tumor showed a (quantitative) decrease in signal intensity relative to that of the liver (79% and 61%) on opposed-phase images, whereas the metastatic component showed an increase in signal intensity (50% and 15%). Similarly, the adrenal lesion-to-spleen signal intensity ratio on opposed-phase images was lower for the adenomatous component in each (0.39 and 0.43) than for the metastatic component (1.17 and 0.90). CONCLUSION: MR imaging can demonstrate and enable characterization of the separate components of collision tumors within the adrenal gland. These findings can be crucial in planning and guiding subsequent percutaneous needle biopsy and patient care.     

Islet cell tumors: comparison of dynamic contrast-enhanced CT and MR imaging with dynamic gadolinium enhancement and fat suppression

Ten patients with 11 islet cell tumors underwent dynamic contrast material-enhanced computed tomography (CT) and magnetic resonance (MR) imaging within a 1-month period. MR imaging depicted all 11 tumors, and CT depicted seven of the 11 tumors. CT did not depict four of seven tumors that measured 2.5 cm in diameter or less. Islet cell tumors had low signal intensity on T1-weighted fat-suppressed MR images, and gastrinomas were best shown with this technique. Two of three insulinomas less than 1.5 cm in diameter were best shown on dynamic contrast-enhanced fast low-angle shot (FLASH) images as uniform areas of high signal intensity. Hepatic metastases were seen in five patients and showed peripheral ringlike enhancement best demonstrated on dynamic gadolinium-enhanced FLASH images. Hepatic lesions were most conspicuous on T2-weighted fat-suppressed spin-echo images. MR imaging with dynamic gadolinium enhancement and fat suppression is a promising tool in the investigation of islet cell tumors.     

Cerebrovascular transit characteristics of DyDTPA-BMA and GdDTPA-BMA on normal and ischemic cat brain

PURPOSE: To compare the efficacy of two nonionic T2*-shortening contrast agents, DyDTPA-BMA dysprodiamide injection and GdDTPA-BMA gadodiamide injection, as perfusion-sensitive MR imaging agents in normal and acutely ischemic brain. METHODS: The magnetic susceptibility effects of intravenous injections of 0.10-0.50 mmol/kg of each contrast agent were quantified on T2-weighted spin-echo images of cat brain before and after unilateral occlusion of the middle cerebral artery by measuring signal intensity changes in the same regions-of-interest in parietal cortex. RESULTS: In normal brain, DyDTPA-BMA produced a significantly greater loss of signal intensity than equimolar doses of GdDTPA-BMA. The magnitude of the signal intensity attenuation was dosage-dependent and proportional to the square of the magnetic moments of the two contrast agents. Restoration of baseline image signal intensity was observed within 30 min after each injection. However, injection of GdDTPA-BMA also produced a delayed, persistent hyperintensity on T2-weighted images, presumably due to its underlying T1-shortening effect. Following unilateral occlusion of the middle cerebral artery, unenhanced T2-weighted images failed to show evidence of cerebral injury for 1.5-3 hours. Administration of 0.10-1.0 mmol/kg DyDTPA-BMA shortened the time for detection of perfusion deficits (residual hyperintensity) in 22 of 36 (61%) treated cats, often to within 30 min after arterial occlusion. DyDTPA-BMA enhancement also improved lesion conspicuity in 26 of 36 (72%) cases, and disclosed very small infarcts that were not visible on T2-weighted precontrast images. Perfusion deficits in areas of partial ischemia were seen more clearly on DyDTPA-BMA-enhanced images than after equimolar injections of GdDTPA-BMA. CONCLUSIONS: Magnetic susceptibility contrast-enhanced MR imaging enables detection of perfusion deficits associated with acute cerebral ischemia well in advance of conventional T2-weighted spin-echo MR imaging without contrast. DyDTPA-BMA appears to delineate regions of ischemic damage better than GdDTPA-BMA.     

MR of spinal cord ganglioglioma

PURPOSE: Our purpose was to describe the MR imaging features in a series of spinal intramedullary gangliogliomas and to compare these findings with the MR features of intramedullary astrocytomas and ependymomas. METHODS: A retrospective analysis was performed of 76 MR examinations in 27 patients with histologically proved spinal ganglioglioma; these were then compared with imaging findings in a representative sample of histologically proved spinal cord astrocytomas and ependymomas. RESULTS: Statistically significant observations regarding spinal gangliogliomas included young age of the patients (mean, 12 years), long tumor length, presence of tumoral cyst, presence of bone erosion and scoliosis, absence of edema, presence of mixed signal intensity on T1-weighted images, and presence of patchy enhancement and cord surface enhancement. A trend (not statistically significant) was noted for holocord involvement and lack of magnetic susceptibility. CONCLUSION: Spinal ganglioglioma can be strongly suspected if MR images reflect the above criteria; however, the ultimate diagnosis still depends on radical resection and appropriate histopathologic investigation.     

Diagnostic and surgical management of spinal dural arteriovenous fistulas

OBJECTIVE: A retrospective review was conducted to compare magnetic resonance (MR) and conventional spinal angiographic images and to investigate the outcome of our treatment protocol for patients with spinal dural arteriovenous fistulas (DAVFs). MATERIALS AND METHODS: Nine patients with a diagnosis of DAVF based on clinical myelopathy and preoperative MR imaging (MRI) and MR angiography (MRA) findings were treated at our institution by the senior author (BAG). All nine patients initially presented with progressive myelopathy. Preoperative MRI revealed T2-weighted signal abnormalities in all patients, and MRA was diagnostic in all patients. Each patient underwent a laminectomy and ligation of the arterialized draining vein. Selective spinal angiograms were used to confirm the level of fistula immediately before the surgical procedure was performed and to document complete obliteration after clip ligation of the medullary draining vein. Follow-up MRI and MRA were performed approximately 2 months postoperatively. RESULTS: MRI T2-weighted signal hyperintensity improved after surgery in all nine patients. Postoperatively, progression of motor weakness and gait difficulty was halted and some improvement was observed in all patients. No patient was neurologically normal, however. To date, there has been no clinical or MRA evidence of recurrence in any patient. CONCLUSION: Preoperative MRA and intraoperative spinal x-ray angiography present as an effective combination for diagnosing and intraoperatively confirming DAVF. Both T1-weighted enhancement and T2-weighted signal hyperintensity on MR images improved after the obliteration of the DAVFs and correlated with clinical improvement in all nine patients. MRA provides adequate visualization and localization of spinal DAVFs and may serve as a useful noninvasive tool for diagnosing and following patients with spinal DAVFs in the future.     

Only visual impressions are almost always present in long-term memories, and reported completeness, accuracy, and verbalizability of recollections increase with age

PURPOSE: To stage advanced cervical carcinoma with conventional or pharmacokinetic magnetic resonance (MR) imaging by correlating imaging findings with whole-mount specimens and histopathologic findings. MATERIALS AND METHODS: Twenty-six adult patients with primary cervical cancer (stages IIB-IVA) underwent T2-weighted turbo spin-echo (SE) MR imaging; gadolinium-enhanced, T1-weighted SE MR imaging; and gadolinium-enhanced, saturation-recovery, turbo fast low-angle shot MR imaging. All imaging findings were correlated with the whole-mount specimens and histopathologic findings. Signal intensity changes versus time were analyzed by using a pharmacokinetic model and parameter values displayed as a color-coded overlay. RESULTS: Histopathologic stages were IIB (n = 9), IIIB (n = 1), and IVA (n = 16). The overall accuracy for tumor staging was 73% for T2-weighted, 81% for T1-weighted, and 92% for pharmacokinetic MR imaging. Pharmacokinetic MR imaging was accurate (90%) in the diagnosis of tumor extension into the bladder and/or rectal wall but inaccurate (69%) in that of parametrial invasion. T2-weighted images were most accurate (86%) in the assessment of parametrial tumor extension but less accurate (69%) in that of bladder or rectal invasion. CONCLUSION: T2-weighted turbo SE images are still superior to contract medium-enhanced T1-weighted SE or pharmacokinetic MR images in the diagnosis of parametrial infiltration by uterine cervical carcinoma. However, pharmacokinetic MR imaging is a promising method for demonstrating and staging IVA disease.     

Preoperative staging of endometrial carcinoma: diagnostic effect of T2-weighted fast spin-echo MR imaging

PURPOSE: To evaluate the usefulness of T2-weighted fast spin-echo magnetic resonance (MR) imaging with a 512 x 256 matrix for assessment of the preoperative stage of endometrial carcinoma. MATERIALS AND METHODS: Twenty-eight women with histopathologically proved endometrial carcinoma underwent preoperative T2-weighted fast spin-echo, dynamic T1-weighted fast spin-echo, and postcontrast T1-weighted spin-echo MR imaging with a phased-array surface coil. The uterine long-axis planes in each sequence were reviewed at separate sessions by three radiologists blinded to the histopathologic data. RESULTS: For the diagnosis of myometrial invasion, no statistically significant differences were found among T2-weighted imaging, dynamic imaging, and postcontrast T1-weighted imaging. For the diagnosis of deep myometrial invasion, T2-weighted and dynamic images showed higher specificity than postcontrast T1-weighted images (T2-weighted, 89%; dynamic, 88%; and postcontrast T1-weighted, 80%). For cervical invasion, T2-weighted and dynamic images showed larger areas under receiver operating characteristic curves than did postcontrast T1-weighted images (T2-weighted, 0.78; dynamic, 0.71; and postcontrast T1-weighted, 0.67). CONCLUSION: T2-weighted imaging is useful for identifying the stage of endometrial carcinoma.     

Arthritic temporomandibular joint: correlation of macromolecular contrast-enhanced MR imaging parameters and histopathologic findings

PURPOSE: To assess the utility of macromolecular contrast material-enhanced magnetic resonance (MR) imaging parameters for determining the histopathologic severity of temporomandibular joint (TMJ) arthritis. MATERIALS AND METHODS: Ovalbumin was used to induce arthritis in the TMJs of 10 previously sensitized adult white rabbits. Five rabbits composed the sham-treated control group. Dynamic spin-echo imaging was performed immediately before and for 30 minutes after injection of macromolecular contrast medium. Histologic specimens of TMJ were assessed quantitatively for arthritis. Changes in MR signal intensity were derived from the synovial and subsynovial tissues of the TMJ, and plasma volume (PV) and permeability surface area product (PS) were calculated. These MR parameters and the arthritic scores were compared between sham-treated and antigen-challenged TMJs. The relationships between MR parameters and histopathologic indexes were also determined. RESULTS: Arthritic TMJs showed marked enhancement of the synovial and subsynovial tissues over the imaging period. PS and all histopathologic indexes of arthritis were significantly greater (P < .005) in antigen-challenged than in sham-treated TMJs. PS demonstrated strong positive relationships with all histologic parameters of arthritis, indicating its utility for assessing the severity of joint inflammation. CONCLUSION: Macromolecular contrast-enhanced MR imaging enables quantification of PS and PV in inflamed joints. This technique may provide insights into the pathogenesis of joint inflammation and noninvasive monitoring of disease severity and treatment response in arthritis.     

The low sensitivity of fluid-attenuated inversion-recovery MR in the detection of multiple sclerosis of the spinal cord

PURPOSE: To confirm the expected superiority of fluid-attenuated inversion-recovery (FLAIR) over conventional fast spin-echo MR imaging in the detection of multiple sclerosis (MS) of the spinal cord. METHODS: Fifteen subjects with known MS involving the spinal cord and brain were studied prospectively. The entire cord was imaged with a phased-array coil on a 1.5-T MR system. Sagittal T1-weighted and fast spin-echo proton density- and T2-weighted images were followed by fast FLAIR images. FLAIR parameters were varied to optimize lesion conspicuity with optimal inversion times (TIs) ranging from 2400 to 2600. Lesion conspicuity and detection were compared between the fast spin-echo and FLAIR images by three radiologists who reached agreement by consensus. RESULTS: The FLAIR technique effectively suppressed cerebrospinal fluid (CSF) signal and reduced CSF pulsation and truncation artifacts in all cases. Shorter imaging parameters (repetition time of 4000 to 6000, TI of 1500 to 2000) uniformly decreased lesion conspicuity in all subjects. Of 11 cord lesions in five subjects imaged with the longer parameters (repetition time of 8000 to 11,000, TI of 2400 to 2600), three were not seen on FLAIR images, four were less conspicuous on FLAIR images, and four were seen equally or better on FLAIR images. CONCLUSION: Although successful in suppressing CSF signal and reducing imaging artifacts, fast FLAIR imaging appears unreliable in the detection of MS lesions in the spinal cord.     

Loss of heterozygosity on the short arm of chromosome 3 in cervical intra-epithelial neoplasia without concomitant cervical carcinoma

OBJECTIVE: To study magnetic resonance (MR) imaging pattern of normal hyaline articular cartilage in the knee joint with regard to the contribution of the "magic angle" effect to the MR signal. DESIGN: Thirty-two healthy volunteers were imaged in a standard supine position in a 1.5-T unit using spin echo and gradient echo sequences. Nine volunteers were reimaged with the knee flexed. The signal behavior of the hyaline cartilage of the femoral condyles was evaluated qualitatively and quantitatively. The extended and flexed positions of the nine volunteers were compared. RESULTS: A superficial and a deep hyperintense layer and a hypointense middle cartilage layer were observed. Segments of increased signal intensity were visible along the condyles; a magic angle effect on signal intensity was evident in the hypointense middle layer with both gradient echo and spin echo images. CONCLUSION: The MR signal behavior of hyaline cartilage is influenced by the alignment of the collagen fibers within the cartilage in relation to the magnetic field. Failure to recognize this effect may lead to inaccurate diagnosis.     

Amyloid arthropathy of the hip joint: MR demonstration of presumed amyloid lesions in 152 patients with long-term hemodialysis

The aim of this study was to determine the spectrum of MR findings of presumed amyloid arthropathy of the hip joints in patients on long-term hemodialysis. We prospectively performed T1- and T2-weighted spin-echo imaging on 152 consecutive patients on hemodialysis. The duration of hemodialysis ranged from 5 months to 24 years, 2 months (mean: 8 years, 8 months). The frequency, location, and signal intensity of bone lesions were assessed. In 12 cases with contrast-enhanced MR examination, enhancement pattern of bone lesions, synovial lesions, and intra-articular lesions were characterized. Bone lesions presumed to be amyloid deposits were identified in 60 patients (39%). Magnetic resonance imaging revealed that amyloid lesions were more extensive than anticipated by plain radiographs. All bone lesions showed decreased signal intensity on T1-weighted images. On T2-weighted images, bone lesions showed increased signal intensity in 32 patients (54%), decreased signal intensity in 11 patients (18%), and both increased and decreased signal intensity in 17 patients (28%). Following intravenous injection of gadolinium-based contrast, all bone lesions showed moderate enhancement. Synovial thickening could not be identified on T1- and T2-weighted images. However, contrast-enhanced images showed thickened synovial membrane, which could be differentiated from joint fluid. Intra-articular nodules showed decreased or intermediate signal intensity on T1-weighted images and decreased signal intensity on T2-weighted images; the intra-articular nodules were contiguous with subchondral bone lesions. Magnetic resonance imaging is useful for evaluating the distribution and extent of amyloidosis of the hip joints in patients undergoing long-term hemodialysis.     

Putamen volume in idiopathic focal dystonia

PURPOSE: To determine the accuracy of magnetic resonance (MR) imaging in evaluating the invasive cervical carcinoma response to concurrent chemotherapy and radiation therapy. MATERIALS AND METHODS: MR imaging was performed before and after concurrent chemotherapy and radiation therapy in 18 patients with locally invasive cervical carcinoma. Surgery followed neoadjuvant therapy in all patients. The presence of a lesion, signal intensity, zonal anatomy integrity, vaginal and parametrial invasion, and lymph node enlargement was determined. Posttreatment MR and histopathologic findings were correlated. RESULTS: Fourteen patients had histopathologic confirmation of MR findings: Twelve had true-negative and two had true-positive findings. (Two had microscopic neoplastic foci beyond the spatial resolution of MR images; these foci do not change surgical treatment planning and probably do not influence prognosis. Therefore, these two patients were considered to have complete response). Four patients had false-positive findings; the hyperintense lesion on posttreatment MR images was due to a tunnel cluster pattern (focal hyperplasia of the endocervical glands with inflammation) in three patients and necrosis in one patient, without any evidence of neoplastic tissue. Thirty-three of 36 parametrial halves and 67 of 72 vaginal fornices were correctly interpreted on posttreatment images. Involvement of three parametrial halves and five fornices was overestimated at MR, because edema or inflammation was not distinguishable from tumor. CONCLUSION: MR imaging is 78% accurate in evaluation of tumor response; in 22% of patients, however, benign conditions were not distinguishable from tumor.     

Contrast enhancement and quantitative signal analysis in MR imaging of multiple myeloma: assessment of focal and diffuse growth patterns in marrow correlated with biopsies and survival rates

OBJECTIVE: This study describes infiltration patterns of multiple myeloma in spinal MR imaging and correlates the findings with biopsies, survival rates, and signal intensity measurements in unenhanced and enhanced studies. MATERIALS AND METHODS: Fifty-three patients with multiple myeloma and 53 age-matched controls underwent MR imaging of the spine. Twenty-nine patients underwent sagittal T1-weighted spin-echo enhanced imaging and all patients underwent sagittal T1-weighted spin-echo unenhanced and opposed-phase gradient-recalled echo images, and signal intensity measurements were taken. MR imaging was correlated to marrow specimens (n = 40) and a clinical staging system. The probability of survival was also calculated. Finally, we performed qualitative visual evaluation (infiltration pattern, degree of tumor involvement) and a quantitative evaluation (marrow signal intensity ratios, contrast enhancement). RESULTS: Five infiltration patterns were found: normal-appearing marrow with low-grade interstitial infiltration (n = 5), focal (n = 18), diffuse (n = 12), focal and diffuse (n = 13), and salt-and-pepper (n = 5). Infiltration pattern correlated with clinical staging; all patients with normal-appearing and salt-and-pepper patterns were clinically stage I. Diffuse marrow infiltration was assessed by marrow ratios: low-grade infiltration, greater than 2.0; intermediate, 1.0-2.0; highgrade, less than 1.0. Contrast enhancement with a signal intensity increase greater than 40% indicated diffuse infiltration. In the control group, all of whom had no marrow disease, enhancement varied (mean +/- SD, 16% +/- 8.9%) but did not exceed 40%. Marrow involvement on MR images correlated significantly with clinical staging and survival (p < or = .001). CONCLUSION: MR imaging with opposed gradient-recalled echo sequences and contrast enhancement provided data that allowed us to classify infiltration patterns and to quantify diffuse marrow involvement in multiple myeloma, both of which correlated to clinical staging and biopsy. Also, the MR data was of prognostic value. Therefore, like laboratory parameters, biopsies, and radiographs, MR imaging can be a supporting pillar in staging and planning treatment of patients with multiple myeloma.     

BRCA1 splice variants BRCA1a and BRCA1b associate with CBP co-activator

PURPOSE: To define the appearance of gastric stromal sarcomas at magnetic resonance (MR) imaging. MATERIALS AND METHODS: Nine patients with gastric stromal sarcoma underwent MR imaging with the following sequences: nonenhanced and gadolinium-enhanced breath-hold, T1-weighted, spoiled gradient-recalled echo (n = 9); fat-suppressed, T2-weighted, fast spin echo (n = 9); and breathing-independent, half-Fourier rapid acquisition with relaxation enhancement (n = 6). Lesion morphology, signal intensity features, and relationships to the gastric wall and surrounding organs were retrospectively evaluated. The diagnosis of gastric stromal sarcoma was histologically proved in all patients. RESULTS: The nine tumors were solitary, multilobulated, shaped irregularly, predominantly exophytic, and large (diameter range, 7-28 cm [mean, 15.8 cm]). The epicenters of all lesions were extrinsic to the stomach, and all lesions arose from the gastric cardia or body. Regions of necrosis and hemorrhage were detected in all cases. Marginal definition on MR images corresponded to histologic grade: High-grade neoplasms possessed ill-defined margins, and low-grade neoplasms demonstrated more well-defined margins. Relationships to surrounding organs depicted at MR imaging corresponded well with histopathologic findings. CONCLUSION: Gastric stromal sarcomas demonstrate characteristic MR imaging features, which correspond well with histopathologic findings. The direct multiplanar capability of MR imaging facilitates delineation of relationships of the tumors to the stomach and surrounding organs.     

Atherosclerotic plaque components in human aortas contrasted by ex vivo imaging using fast spin-echo magnetic resonance imaging and spiral computed tomography

RATIONALE AND OBJECTIVES: Imaging techniques that distinguish atherosclerotic plaque components may be useful in identifying the nature of the atherosclerotic lesion and determining the best method of treatment for obstructive vascular mining the best method of treatment for obstructive vascular disease. This study compares fast spin-echo (FSE) magnetic resonance (MR) and spiral computed tomography (CT) images of excised human atherosclerotic aortas to determine which imaging technique provides the best contrast between plaque components ex vivo. METHODS: Aortas were imaged using four FSE sequences in MR with and without frequency-selective fat saturation, and using spiral CT without contrast. The average signal intensity of a region of calcification, thrombosis, fatty plaque, and normal vessel wall was measured on all images and compared. RESULTS: The use of fat saturation pulses in MR did not significantly alter the signal from atherosclerotic plaque for the sequences used. Proton density-weighted FSE sequences that collected early echoes were better than other FSE sequences and CT at differentiating calcification from all soft tissues. T2-weighted FSE sequences that collected later echoes were best at soft-tissue discrimination. CONCLUSIONS: The FSE techniques used were superior to nonenhanced spiral CT in discriminating plaque components ex vivo, including calcification.     

Chondroblastoma: classic and confusing appearance at MR imaging

PURPOSE: To define the characteristics of chondroblastoma at magnetic resonance (MR) imaging and the combination of findings that are diagnostic for chondroblastoma. MATERIALS AND METHODS: From January 1987 through December 1992, 22 patients with histologically confirmed chondroblastoma and prior MR imaging examinations were seen. Patients included 16 men and six women, aged 10-58 years (median, 17 years). Retrospective analysis of findings at MR imaging, plain radiography, computed tomography, and bone scanning was performed. RESULTS: Low to intermediate heterogeneous signal intensity, lobular internal architecture, and fine lobular margins were well defined with high-resolution T2-weighted (repetition time > or = 1,500 msec, echo time > or = 70 msec) MR imaging. Adjacent bone-marrow and soft-tissue edema and periosteal reactions were more dramatically demonstrated on MR images than on radiographs. Bone marrow edema was prominent in all but five cases. Obvious periosteal reaction and adjacent soft-tissue edema were visible in 17 cases. CONCLUSION: Knowledge of the MR imaging findings of chondroblastoma will allow accurate diagnosis and help avoid confusion with infection and aggressive neoplasms.