MR imaging of spinal lymphoma.

Fourteen patients with spinal lymphoma examined by MR imaging were reviewed. Thirteen of them also had extraspinal lymphoma. Vertebral involvement was found in 12 patients, epidural in 10, and paraspinal in 8 patients. On the basis of MR imaging at 0.3 T, spinal lymphoma may be divided into three types of growth pattern according to the main location: paraspinal, vertebral, and epidural. Most frequently, all three locations were found simultaneously on MR (7/14). In one patient the location was vertebral with epidural extension, in one paraspinal with vertebral extension, in 3 it was entirely vertebral, and in 2 entirely epidural. Multiple plane T1-weighted imaging gave complete information about the extent of spinal lymphoma. The signal intensity was lower than or equal to muscle and lower than bone marrow in paraspinal and vertebral lesions on T1-weighted images and high on T2-weighted images. Epidural lesions showed a hypo- or isointense signal relative to the cord on T1-weighted images except in one case and a hyperintense signal on T2-weighted images. Compression of the cord and cauda equina due to bulging of diseased vertebral bodies and epidural lesions was well demonstrated. MR imaging was also found useful in the follow-up of treatment.     

Mediastinal lymphoma: quantitative changes in gadolinium enhancement at MR imaging after treatment

PURPOSE: To compare changes in gadolinium enhancement at magnetic resonance (MR) imaging with outcome in mediastinal lymphoma after treatment. MATERIALS AND METHODS: Thirty-one patients with bulky mediastinal lymphoma (17 with Hodgkin disease, 14 with non-Hodgkin lymphoma) underwent serial MR imaging before and up to 50 months after treatment, with routine follow-up (including computed tomography). Signal intensity ratios between masses and muscle were calculated on T1-weighted, T2-weighted, and contrast material-enhanced T1-weighted spin-echo MR images. The percentage enhancement and signal intensity ratios of mediastinal masses on T2-weighted MR images were calculated at diagnosis and during and after treatment. RESULTS: Twenty-one patients with persistent complete remission had a mean percentage enhancement of residual masses (4%; range, -26% to 40%) that was significantly lower than that of initial masses (78%; range, 41%-124%). Although the mean signal intensity ratio of residual masses on T2-weighted images was significantly lower than that of initial masses, an increase in this ratio was observed in four patients after treatment. In seven patients with relapse, the percentage enhancement value of the residual mass was as high as that of the initial mass. CONCLUSION: Gadolinium enhancement of lymphomatous masses of the mediastinum decreased markedly after treatment in patients in continuous complete remission but not in patients with relapse.     

脊柱区淋巴瘤的MRI特征

目的 分析脊柱区淋巴瘤的MRI表现,以提高对其的认识.方法 回顾性分析经手术及穿刺病理或临床随访证实的脊柱区淋巴瘤45例,其中原发性5例,均为非霍奇金淋巴瘤(NHL);继发性4|D例,其中霍奇金淋巴瘤(HL)9例,NHL 31例(B细胞型27例,T细胞型4例).将MRI表现与临床、病理结果进行对照.结果 (1)病变部位:单部位发病者13例,多部位发病者32例.5例原发性者均为单部位发病,继发性者40例中32例为多发.(2)病变类型:骨质破坏型27例,表现为不同程度的骨质破坏,23例合并有软组织肿块,18例软组织病变的范围超过骨质破坏的范围;软组织肿块型6例,骨质破坏不明显,5例表现为椎管内外软组织肿块并经椎间孔相连,呈围椎、钻孔生长的特点;骨髓浸润型9例,表现为椎骨髓质MRI信号异常,骨皮质完整,椎旁软组织正常;脊髓浸润型3例,表现为脊髓增粗和MRI信号异常.(3)MRI表现:椎骨骨质破坏和骨髓浸润表现为T1WI低信号,T2WI低、等或高信号,压脂T2WI高信号.软组织肿块与相邻正常肌肉相比,T1WI呈均匀低信号,T2WI呈高信号.增强扫描肿块多呈轻至中度强化,坏死液化不明显.结论 脊柱区淋巴瘤多为继发性B细胞NHL,其主要表现是溶骨性骨质破坏伴较大范围的软组织肿块,肿块有经椎间孔相连围椎、钻孔生长的特点,增强扫描呈轻至中度均匀强化.     

Intracranial hemangiopericytomas: MR and CT features.

PURPOSETo describe the MR and CT imaging features of hemangiopericytoma and to identify the characteristics that might distinguish them from meningioma.METHODSWe retrospectively reviewed the CT and MR findings in 34 pathologically proved cases of hemangiopericytoma. We evaluated the size, shape, and location of the tumor; the presence of hydrocephalus, edema, and mass effect; the type of dural attachment (broad-based or narrow-based) and bone changes (erosion, hyperostosis); and the tumor''s density, signal, and contrast-enhancement characteristics.RESULTSThirty of 34 tumors were 4 cm or more in greatest dimension, 32 were lobular, and only seven were in the posterior fossa. Hydrocephalus was present in 18, edema in 30, and mass effect in 33. Twenty-three had broad-based dural attachment and 11 had narrow-based attachment. All 26 unenhanced CT scans showed hyperdense tumors; 19 were heterogeneous and seven homogeneous. All 27 contrast-enhanced CT scans showed enhancement; 17 were heterogeneous and 10 homogeneous. Bone erosion was present in 17 of 29 hemangiopericytomas imaged with CT. None had hyperostosis or tumor calcifications. On T1-weighted MR images, 13 of 17 tumors were isointense with cortical gray matter; on T2-weighted image, 10 of 17 were isointense. All 14 tumors imaged with contrast enhanced T1-weighted MR imaging showed enhancement, and 13 of these were heterogeneous; eight of the 14 had a "dural tail" sign.CONCLUSIONIntracranial hemangiopericytomas are multilobulated, extraaxial tumors, sometimes associated with narrow-based dural attachment and bone erosion. Unlike with meningiomas, hyperostosis and intratumoral calcification are not present.     

原发性骨骼肌非霍奇金淋巴瘤的影像学表现

目的 分析原发性骨骼肌非霍奇金淋巴瘤（NHL）的影像学表现，以期提高对其的认识。方法 经病理证实的原发性骨骼肌NHL5例，均为B细胞来源。其中3例有MR和CT检查，1例仅有CT检查，1例仅有MR检查。2例有X线平片，2例有核素骨显像。结果所有患者均表现为受累肌肉弥漫性肿胀，肌肉轮廓可辨。4例CT平扫密度均匀，与未受累肌肉相近；增强扫描呈轻度强化2例，中等强化1例，强化密度均匀。MR扫描4例，平扫T1WI与周围肌肉相比呈稍低信号，T2WI信号明显高于周围未受累的肌肉。肿瘤内部的信号均匀，未见明显液化坏死区。增强扫描2例肿瘤为均匀强化，强化信号明显高于周围正常肌肉信号。X线平片2例显示骨质未被破坏。核素骨显像2例显示软组织肿块浓聚，骨髓的信号未见异常。结论 原发性骨骼肌NHL的影像学表现有一定的特点，MRI是其最佳的影像学检查方法。     

The variable MR appearance of primary lymphoma of the central nervous system: comparison with histopathologic features.

PURPOSETo describe the MR features of primary central nervous system (CNS) lymphoma and to determine whether there is a correlation with histopathologic findings.METHODSThe MR images, pathologic specimens, and clinical records of 23 patients with primary CNS lymphoma were reviewed. The imaging and pathologic characteristics were tabulated and compared by using the standard tests for association in a two-dimensional contingency table.RESULTSA total of 61 lesions were present in 23 patients; 12 patients (52%) had multiple lesions. All lesions were isointense or hypointense on T1-weighted images, and 53% were isointense or hypointense on T2-weighted images. Twenty patients received intravenous contrast material, and 43 (91%) of 47 lesions enhanced. The three patients who had nonenhancing lesions received steroids before the initial MR studies. Enhancement patterns differed between the immunocompetent and the immunocompromised hosts, with the latter group harboring a higher percentage of rim-enhancing lesions. Twenty-seven (44%) of the lesions were centered in a cerebral hemisphere and 14 (23%) were centered in the central gray matter. There was a statistically significant correlation between a higher degree of necrosis histologically and hyperintensity on T2-weighted MR images. The degree of necrosis also showed a positive correlation with rim enhancement.CONCLUSIONSPrimary CNS lymphoma has a variable MR appearance that correlates with the severity of intratumoral necrosis. These imaging characteristics, as well as lesion location, mean lesion size, and proclivity to harbor necrosis, are altered in the immunocompromised host.     

颅内原发性中枢神经系统淋巴瘤的MRI研究

目的研究颅内原发性中枢神经系统淋巴瘤（PCNSL）的MRI表现特点。资料与方法回顾性分析23例颅内PCNSL的MRI表现。抽取恶性胶质瘤30例、颅内转移瘤30例,共60例归为非PCNSL组作为对照。观察肿瘤部位、分布、信号、形态,并进行统计学分析。结果颅内PCNSL好发于深部脑组织,如胼胝体、丘脑及基底节区,多发病灶多呈区域性分布;肿瘤T2WI多呈等或稍高信号,甚至低信号,扩散加权像（DWI）呈均匀高信号;增强扫描多呈均匀明显强化,肿瘤周围可见“尖突征”。与非PCNSL组之间差异有统计学意义（P〈0．01）。结论颅内PCNSL影像表现多样,但具有一定特征。     

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.     

Supratentorial parenchyma in the developing fetal brain: in vitro MR study with histologic comparison.

PURPOSETo assess the in vitro MR signal of the developing brain through histologic comparisons.METHODSFive healthy fetal specimens aged 16, 19, 22, 27, and 34 gestational weeks were studied in vitro using T1- and T2-weighted sequences in frontal and axial planes. Neuropathologic studies included sections in the same frontal plane. Comparison of histologic sections with measurements of the relative widths of the layers of different signal intensities enabled us to assign cellular correspondence to each MR layer.RESULTSIn the cerebral mantle, a layered pattern was observed on both T1- and T2-weighted images. In the basal ganglia, signal from the pallidum and thalamus was isointense with white matter from 16 to 22 weeks'' gestation; then, from 27 and 34 weeks'' gestation, the signal was relatively high on T1-weighted images and low on T2-weighted images. The neostriatum had a relatively low signal on T1-weighted images and a high signal on T2-weighted images from 16 to 27 weeks'' gestation: then, at 34 weeks'' gestation, the signal was relatively high on T1-weighted images and low on T2-weighted images.CONCLUSIONMR imaging can clearly show specific patterns of growing fetal brain in vitro.     

Imaging of periosteal osteosarcoma: radiologic-pathologic comparison

PURPOSE: To review the imaging appearance of periosteal osteosarcoma, with pathologic comparison. MATERIALS AND METHODS: Data for 40 pathologically confirmed periosteal osteosarcomas were retrospectively reviewed. Patient demographic data were recorded, and radiographs (n = 40), bone scintigrams (n = 10), angiograms (n = 2), and computed tomographic (CT) (n = 11) and magnetic resonance (MR) (n = 12) images were evaluated for lesion location and size, cortical changes, marrow involvement, and intrinsic characteristics by two musculoskeletal radiologists, with agreement by consensus. Pathology reports were reviewed for presence and predominance of histologic components (fibrous, chondroid, and osteoid), tumor grade, and marrow involvement. RESULTS: There were 25 male (62%) and 15 female (38%) patients with an age range of 10-37 years (average age, 20 years). The most frequent lesion locations were the diaphysis of the tibia (16 patients) or of the femur (15 patients). Radiographs showed a broad-based soft-tissue mass that was attached to the cortex (all patients) and showed cortical thickening (33 patients), cortical scalloping/erosion (37 patients), and/or perpendicular periosteal reaction (38 patients) extending into the soft-tissue mass. Soft-tissue masses were well defined in 91%-100% of cases and surrounded a median of 50%-55% of the cortex. Lesions commonly showed low attenuation at CT (10 patients) and high signal intensity on T2-weighted MR images (10 patients), reflecting the high water content of these largely chondroblastic lesions. Focal areas of adjacent marrow replacement were common at MR imaging (nine patients) but represented reactive changes unless they were in direct continuity with the overlying soft-tissue mass (this was rare, occurring in only one patient, and represented marrow invasion). Review of pathology reports revealed that all lesions contained chondroid tissue, which predominated in 34 patients. CONCLUSION: The radiologic appearance of periosteal osteosarcoma is a broad-based surface soft-tissue mass causing extrinsic erosion of thickened underlying diaphyseal cortex and perpendicular periosteal reaction extending into the soft-tissue component. Reactive marrow changes are commonly seen at MR imaging, but true marrow invasion is rare.     

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.     

Advanced imaging of melorheostosis with emphasis on MRI

Objective: To describe the CT and MR imaging appearance of both osseous and extraosseous manifestations of melorheostosis. Design and patients: We retrospectively reviewed the CT (n=7) and/or MR imaging findings (n=12) of 17 patients with characteristic radiographic findings of melorheostosis (undulating cortical hyperostosis with marked uptake on radionuclide bone scintigraphy). Results: CT and MR imaging revealed cortical hyperostosis as high attenuation and low signal intensity on all MR pulse sequences, respectively. Encroachment on the marrow space was seen in all cases resulting from endosteal involvement. Thirteen patients demonstrated 14 soft tissue masses with infiltrative margins in 80% of cases and seven showed extensive mineralization on CT or MR imaging (low intensity on all pulse sequences). Seven soft tissue masses were predominantly nonmineralized with intermediate signal intensity on T1-weighted and intermediate to high signal on T2-weighted MR images corresponding to vascularized fibrous tissue with variable collagen content pathologically. Enhancement after intravenous gadolinium was seen in all patients imaged with soft tissue masses (n=2). Two patients demonstrated muscle atrophy resulting from nerve involvement. Conclusions: The osseous abnormalities in melorheostosis are identical on advanced imaging and radiographs. Mineralized or nonmineralized soft tissue masses should be recognized as another manifestation of this disease as opposed to a more ominous finding, making biopsy unwarrranted. Received: 16 January 2001 Accepted: 21 February 2001     

Diffusion-weighted MR imaging offers no advantage over routine noncontrast MR imaging in the detection of vertebral metastases

BACKGROUND AND PURPOSE: Diffusion-weighted MR imaging of the spine has been used to differentiate benign from pathologic vertebral body compression fractures. We sought to determine the utility of diffusion-weighted MR imaging in the detection of vertebral metastases and to compare it with conventional noncontrast T1- and T2-weighted MR imaging. METHODS: Fifteen patients with metastases to the spine were studied using conventional MR imaging and diffusion-weighted imaging. Blinded review of all images was undertaken, and patients were categorized according to whether they had focal or multiple lesions. The signal intensity of the lesions was compared on T1-, T2- (fast spin-echo), and diffusion-weighted images. RESULTS: In five patients with focal disease, metastases were hypointense on T1-weighted images; hypointense (n = 2), isointense (n = 1), or hyperintense (n = 2) on T2-weighted images; and hypointense (n = 3) or hyperintense (n = 2) on diffusion-weighted images with respect to presumed normal bone marrow. In 10 patients with disease in multiple sites, all lesions were hypointense on T1-weighted images; hypointense (n = 2), isointense (n = 4), hyperintense (n = 2), or mixed (n = 2) on T2-weighted images; and hypointense (n = 5), hyperintense (n = 3), or mixed (n = 2) on diffusion-weighted images with respect to presumed normal bone marrow. CONCLUSION: As used in this study, diffusion-weighted MR imaging of the spine showed no advantage in the detection and characterization of vertebral metastases as compared with noncontrast T1-weighted imaging, but was considered superior to T2-weighted imaging.     

Patterns of lesion development in multiple sclerosis: longitudinal observations with T1-weighted spin-echo and magnetization transfer MR.

PURPOSEWe evaluated the appearance of enhancing multiple sclerosis (MS) lesions on unenhanced T1-weighted MR images and the natural course of enhancing MS lesions on serial unenhanced T1-weighted and magnetization transfer (MT) MR images.METHODSOne hundred twenty-six enhancing lesions were followed up monthly for 6 to 12 months to determine their signal intensity on unenhanced T1-weighted and MT MR images. At the time of initial enhancement, the size of the lesion and the contrast ratio of enhancement were calculated for each enhancing lesion. During follow-up, the contrast ratio on the corresponding unenhanced T1-weighted image was measured, and an MT ratio (MTR) was calculated.RESULTSTwenty-five enhancing lesions (20%) appeared isointense and 101 lesions (80%) appeared hypointense relative to normal-appearing white matter on unenhanced T1-weighted images. During 6 months of follow-up, four MR patterns of active lesions were detected: initially isointense lesions remained isointense (15%); initially isointense lesions became hypointense (5%, most of which reenhanced); initially hypointense lesions became isointense (44%); and initially hypointense lesions remained hypointense (36%). MTR was significantly lower for hypointense lesions as compared with isointense lesions at the time of initial enhancement. For lesions that changed from hypointense to isointense, MTR increased significantly during 6 months of follow-up. Multiple regression analysis showed that strongly decreased MTR at the time of initial enhancement and enhancement duration of more than one scan were predictive of a hypointense appearance on unenhanced T1-weighted images at 6 months'' follow-up. Ring enhancement was found to be the only (weak) predictor of persistently hypointense signal intensity.CONCLUSIONMost enhancing lesions appear slightly to significantly hypointense on unenhanced T1-weighted images. Although most hypointensities are reversible, only those lesions that fail to recover on unenhanced T1-weighted and MT images may have considerable irreversible structural changes.     

Hip pain in three children accompanied by transient abnormal findings on MR images

In a study of three children experiencing hip pain, low-signal-intensity patterns in the femoral head on T1-weighted magnetic resonance (MR) images eventually resolved, reverting to the normal signal patterns. These findings occurred in conjunction with documented clinical improvement of the patients' condition. T2-weighted images revealed isointense signals initially at the abnormal sites. Isointense signals prevailed on follow-up T2-weighted images. These MR imaging findings are likely due to transient bone marrow edema. These findings support the apparent sensitivity of MR imaging in the evaluation of marrow-based pathologic processes. Some pediatric patients with hip pain may have signs of transient bone marrow edema, rather than avascular necrosis, on MR images. Conservative management should be considered in such cases.     

The value of MR imaging in distinguishing leiomyomas from other solid pelvic masses when sonography is indeterminate

The differentiation of a uterine leiomyoma from other solid pelvic masses on sonography is usually straightforward. Occasionally, the sonographic appearance of a pedunculated uterine leiomyoma may simulate that of a solid adnexal mass. The purpose of this study was to determine if MR imaging adds specificity to the diagnosis of indeterminate solid pelvic masses visualized with sonography. Nineteen patients were imaged with MR after sonography revealed the presence of a solid pelvic mass adjacent to the uterus but could not be used to determine whether the mass was a leiomyoma or some other type of tumor. The diagnostic criteria for a leiomyoma on MR imaging included (1) the presence of a mass adjacent to the uterus and (2) a mass that was predominantly low signal intensity or isointense compared with normal myometrium on T1-weighted images and predominantly low signal intensity on T2-weighted images. In 11 of 13 patients, the masses that met these MR criteria for leiomyoma were proved to be uterine leiomyomas at surgery. Another mass that met the criteria was shown to be a leiomyoma in the broad ligament; the other was an ovarian fibroma. Of the six cases that did not meet the MR criteria for the diagnosis of leiomyoma, three were proved to be degenerated fibroids, one was squamous cell carcinoma of the cervix, and two were ovarian malignant tumors. Because leiomyomas often have an MR appearance that is distinct from that of solid pelvic malignant tumors, MR imaging can be useful for the diagnosis of some indeterminate solid pelvic masses.     

SSH-EPI diffusion-weighted MR imaging of the spine with low b values: is it useful in differentiating malignant metastatic tumor infiltration from benign fracture edema?

Objective  Conventional MR sequences are sometimes not helpful in differentiating benign from pathologic fractures. Our aim was to evaluate the usefulness of single-shot echo-planar imaging sequences (diffusion-weighted imaging (DWI)/SSH-EPI) with low b value in differentiating malignant metastatic tumor infiltration of vertebral bone marrow from benign vertebral fracture edema. Materials and methods  A total of 47 patients, 20 with benign fractures and 27 with tumor infiltration, were included in this prospective study. Diffusion-weighted MR images were obtained by single-shot echo-planar imaging technique with diffusion gradient (b = 300 s/mm²; TR/TE, 1,400/100), using a 1.5 T MR scanner. T1- and T2-weighted images and short inversion time inversion-recovery images were available for all 64 lesions. The lesions on DWI/SSH-EPI were categorized as having hypo-, iso-, or hyperintense signal intensity relative to normal vertebrae by two experienced radiologists. Results  We evaluated signal intensity patterns on DWI/SSH-EPI in 64 lesions, which showed low signal intensity on T1-weighted images in both benign fractures and metastasis. With the exception of sclerotic metastases in two patients, malignant metastatic tumor infiltration was hyperintense with respect to normal bone marrow on diffusion-weighted images; all but four benign vertebral fractures were isointense with respect to normal bone marrow. Conclusion  Single-shot echo-planar imaging sequences (DWI/SSH-EPI) with low b value provided excellent distinction between metastatic tumor infiltration and benign vertebral fracture edema. Hyperintense signal intensity on DWI/SSH-EPI was highly specific for the diagnosis of metastatic tumor infiltration of the spine.     

MR signal intensity characteristics in Legg-Calvé-Perthes disease. Value of fat-suppressed (STIR) images and contrast-enhanced T1-weighted images

PURPOSE: To evaluate the MR signal intensity characteristics in Legg-Calvé-Perthes disease on fat-suppressed (STIR) images and contrast-enhanced T1-weighted spin-echo images, and to develop criteria for the administration of contrast material. MATERIAL AND METHODS: Twenty children with Legg-Calvé-Perthes disease underwent conventional radiography and MR imaging of the hip utilizing fat-suppressed (STIR) sequences and T1-weighted spin-echo sequences before and after i.v. contrast administration. The signal intensity characteristics of the femoral head and the proximal femoral metaphysis were assessed retrospectively by two pediatric radiologists. RESULTS: Evaluation of the MR images revealed six different signal patterns within the femoral head: 1) isointense signal on all images; 2) complete signal void on all images; 3) hyperintense signal on STIR images with; or 4) without contrast enhancement on T1-weighted spin-echo images; 5) isointense signal on STIR images with; or 6) without contrast enhancement on T1-weighted images. Within the metaphysis three different signal patterns were differentiated. CONCLUSION: Combination of fat-suppressed (STIR) sequences and T1-weighted pre- and post-contrast sequences allows an accurate evaluation of Legg-Calvé-Perthes disease. In patients without signal alterations or complete signal loss on fat-suppressed and T1-weighted spin-echo images, administration of i.v. contrast is not necessary. In case of bone marrow edema on fat-supressed images, contrast-enhanced T1-weighted images are required to identify viable osseous fragments.     

MR imaging of the normal and abnormal clivus

We retrospectively reviewed 330 T1-weighted sagittal images, 80 T2-weighted sagittal images, and 83 gadopentetate-dimeglumine-enhanced scans of normal adults to determine the MR appearance of the normal adult clivus. MR images of 21 patients with an abnormal clivus (19 with tumor invasion and two with marrow reconversion) were also evaluated restrospectively and compared with those of the control group to assess MR features distinguishing the two groups. Our study revealed that a normal adult clivus consisted of low- and high-intensity portions mixed in various proportions on T1-weighted images. The low-intensity portion was isointense or hyperintense relative to the pons and always contained foci of bright signal intensity. The low-intensity tumor of a pathologic clivus tended to be hypointense relative to the pons (17/19), and was completely devoid of foci of bright signal intensity. The normal adult clivus was approximately isointense relative to the pons on T2-weighted images. Clival tumors were grossly hyperintense relative to the pons on T2-weighted images in 11 of 17 patients. In the remaining six patients, either a portion of or the entire lesion was isointense relative to the pons and, therefore, was not detectable on T2-weighted images. A normal adult clivus can enhance to some degree (19/83). Clival tumors were found to enhance intensely. A clivus of very low signal intensity (signal void) on T1- or T2-weighted images was always abnormal. The clivus with marrow reconversion was uniformly hypointense relative to the pons on T1-weighted images and isointense relative to normal marrow on T2-weighted images.(ABSTRACT TRUNCATED AT 250 WORDS)     

MR detection of iliac bone marrow involvement by malignant lymphoma with various MR sequences including diffusion-weighted echo-planar imaging

OBJECTIVE: To assess the diagnostic accuracy of MR imaging for detecting bone marrow infiltration by malignant lymphoma. PATIENTS AND DESIGN: Fifty-three patients with malignant lymphoma underwent MR imaging and bone marrow biopsy. In 80 iliac crests of the 53 patients (13 positive specimens in 9 patients and 67 negative specimens in 44 patients), biopsy results and the signal intensity characteristics were compared. MR sequences included T1-weighted SE, T2-weighted FSE with fat suppression, FSE STIR, and diffusion-weighted EPI with fat suppression at 1.5 T. RESULTS AND CONCLUSIONS: To detect lymphoma infiltration, T1-weighted SE had the highest sensitivity (92%) and diffusion-weighted EPI with fat suppression and FSE STIR had the highest specificity (92.5% and 92%, respectively). A combination of T1-weighted SE and FSE STIR yielded the highest sensitivity and specificity (85% and 97%, respectively). A combination of T1-weighted SE and FSE STIR sequences seems to be the current choice of imaging protocol for detecting bone marrow infiltration by malignant lymphoma.