MR imaging in toxoplasmosis encephalitis after bone marrow transplantation: paucity of enhancement despite fulminant disease

We present a patient who underwent bone marrow transplantation (BMT) after developing chronic myelocytic leukemia. Four months after BMT, he became comatose and died. MR imaging revealed multifocal brain lesions that were progressive but produced no edema. Postcontrast studies revealed that most of the lesions were nonenhancing. There was only discrete, irregular leptomeningeal enhancement with possible minimal enhancement of the cortex and subcortical white matter. Autopsy showed overwhelming toxoplasmosis encephalitis. This case illustrates that toxoplasmosis lesions may lack obvious contrast enhancement in the brain of the immunocompromised patients, despite severe involvement. Recognition of this unusual MR imaging manifestation of toxoplasmosis should lead to earlier diagnosis and treatment.     

Correlation between bone marrow edema and collapse of the femoral head in steroid-induced osteonecrosis

OBJECTIVE: The purpose of this study was to clarify whether bone marrow edema is detectable on initial MR imaging of steroid-induced osteonecrosis of the femoral head. SUBJECTS AND METHODS: Forty-eight hips with osteonecrosis were examined consecutively with MR imaging and radiography. In a previously reported screening program, osteonecrosis was diagnosed on MR imaging when subchondral bands of abnormal signals were present. In the screening program, the MR images of 200 hips of 100 patients receiving high-dose steroid therapy were examined prospectively. Subchondral bands were detected in 48 hips at a mean of 14 weeks after the initiation of steroid therapy. RESULTS: On follow-up MR imaging of 47 hips (one hip excluded) bone marrow edema was initially observed in 13 hips after the onset of hip pain. MR imaging of the remaining 34 hips did not reveal bone marrow edema and the patients were all asymptomatic. MR imaging of 31 of the 34 hips continued to show subchondral bands and MR imaging of the other three hips indicated that the subchondral bands had disappeared. When bone marrow edema was detectable, abnormal findings on radiography were slight but 11 (85%) of the 13 hips progressed to advanced osteonecrosis. Bone marrow edema was highly correlated with the subsequent collapse of the femoral head (p<0.0001). CONCLUSION: Bone marrow edema was not present on initial MR imaging of osteonecrosis. Bone marrow edema should be considered a marker for potential progression to advanced osteonecrosis, and careful examinations for osteonecrosis are necessary when bone marrow edema is seen.     

Bone marrow edema pattern in osteoarthritic knees: correlation between MR imaging and histologic findings

PURPOSE: To correlate magnetic resonance (MR) images of a bone marrow edema pattern with histologic findings in osteoarthritic knees. MATERIALS AND METHODS: Sixteen consecutive patients (age range, 43-79 years; mean, 67 years) referred for total knee replacement were examined with sagittal short inversion time inversion-recovery (STIR) and T1- and T2-weighted turbo spin-echo MR imaging 1-4 days before surgery. Tibial plateau abnormalities on MR images were compared quantitatively with those on histologic maps. RESULTS: The bone marrow edema pattern zone (ill-defined and hyperintense on STIR images and hypointense on T1-weighted MR images) mainly consisted of normal tissue (53% of the area was fatty marrow, 16% was intact trabeculae, and 2% was blood vessels) and a smaller proportion of several abnormalities (bone marrow necrosis [11% of area], abnormal [necrotic or remodeled] trabeculae [8%], bone marrow fibrosis [4%], bone marrow edema [4%], and bone marrow bleeding [2%]). The bone marrow edema pattern zone and the zone with a normal MR imaging appearance differed significantly in the presence of bone marrow necrosis (P =.021), bone marrow fibrosis (P =.014), and abnormal trabeculae (P =.011) but not in the prevalence of bone marrow edema (P =.069). Bone marrow edema also was found in zones with an unremarkable MR appearance (perifocal zone, 5% edema; control zone, 2% edema). CONCLUSION: A bone marrow edema pattern in osteoarthritic knees represents a number of noncharacteristic histologic abnormalities. Edema is not a major constituent of MR imaging signal intensity abnormalities in such knees.     

Magnetic resonance imaging of the spinal marrow: Basic understanding of the normal marrow pattern and its variant

For now, magnetic resonance (MR) is the best noninvasive imaging modality to evaluate vertebral bone marrow thanks to its inherent soft-tissue contrast and non-ionizing nature. A daily challenging scenario for every radiologist interpreting MR of the vertebral column is discerning the diseased from normal marrow. This requires the radiologist to be acquainted with the used MR techniques to judge the spinal marrow as well as its normal MR variants. Conventional sequences used basically to image marrow include T1W, fat-suppressed T2W and short tau inversion recovery (STIR) imaging provides gross morphological data. Interestingly, using non-routine MR sequences; such as opposed phase, diffusion weighted, MR spectroscopy and contrasted-enhanced imaging; may elucidate the nature of bone marrow heterogeneities; by inferring cellular and chemical composition; and adding new functional prospects. Recalling the normal composition of bone marrow elements and the physiologic processes of spinal marrow conversion and reconversion eases basic understanding of spinal marrow imaging. Additionally, orientation with some common variants seen during spinal marrow MR imaging as hemangiomas and bone islands is a must. Moreover, awareness of the age-associated bone marrow changes as well as changes accompanying different variations of the subject’s health state is essential for radiologists to avoid overrating normal MR marrow patterns as pathologic states and metigate unnecessary further work-up.     

恶性血液肿瘤脊柱骨髓弥漫性浸润的动态对比增强MR灌注成像

目的 评价动态对比增强MR灌注成像对恶性血液肿瘤脊柱骨髓弥漫性浸润性病变的诊断价值. 资料与方法 经骨髓组织活检确诊的恶性血液肿瘤26例和20例正常对照者行腰椎动态对比增强MR灌注成像检查.计算峰值增强百分率(Emax)、增强斜率(ES)和到达峰值时间(TTP). 结果 脊柱骨髓弥漫性恶性浸润组与正常对照组间的Emax、ES和TTP均具有显著差异(P<0.01).骨髓轻度浸润和中度浸润之间的Emax、ES和TTP均具有显著差异(P<0.05).骨髓轻度浸润和重度浸润之间的Emax、ES和TTP均具有显著差异(P<0.01).骨髓中度浸润和重度浸润之间的Emax、ES和TTP无显著差异(P>0.05).Emax、ES和骨髓浸润程度之间具有正相关性(P<0.01),TTP和骨髓浸润程度之间具有负相关性(P<0.01). 结论 动态对比增强MR灌注成像可以判断恶性血液肿瘤是否出现脊柱骨髓弥漫性浸润,灌注参数可以反映骨髓肿瘤细胞浸润程度.     

Bone marrow edema syndrome of the foot: one year follow-up with MR imaging

OBJECTIVE: To describe the MR findings of bone marrow edema syndrome (BMES) of the foot and its evolution at 1 year follow-up. DESIGN AND PATIENTS: Twenty-five of 32 patients with disabling foot and ankle pain unrelated to trauma diagnosed as BMES when MR imaging demonstrated a bone marrow edema pattern in one or more bones without any radiological or underlying clinical cause, were re-evaluated by MR imaging 1 year later. RESULTS: On the initial MR examinations an average of 4.7 individual bones were involved by bone marrow edema. Soft tissue edema was present in every patient and joint effusion in 10 patients. MR imaging at 1 year showed resolution of bone edema in 18 patients (72%), partial improvement in five (20%) and no improvement in two (8%). Six patients (24%) developed similar symptoms in the other foot during follow-up. Ten of 17 available plain radiographs showed some loss of radiodensity. Further bone marrow edema developed in bones of the same foot that were initially normal, or in uninvolved distant bone marrow areas in the same affected bone, in six of seven patients on follow-up MR imaging. CONCLUSIONS: The evolution of the MR findings of BMES of the foot is to complete resolution or partial improvement at 1 year in the majority of cases. Migration to the other foot occurs in up to a quarter of patients.     

Magnetic resonance evaluation of cerebral toxoplasmosis in patients with the acquired immunodeficiency syndrome

PURPOSE: To evaluate and delineate the characteristics of cerebral toxoplasmosis lesions using a combination of magnetic resonance (MR) spectroscopy, diffusion, and perfusion studies. MATERIAL AND METHODS: A total of 8 patients with 23 lesions were evaluated on a 1.5-T MR system. Diffusion-weighted imaging (DWI) was performed with three 'b' values of 50, 500, and 1000 s/mm2, and the apparent diffusion coefficient maps were calculated. The diffusion-weighted appearances and the T2-weighted MR appearances of the lesions were compared. MR spectroscopy was performed using the point-resolved single-voxel technique with two TE values of 135 ms and 270 ms. Perfusion studies were carried out using the dynamic contrast-enhanced technique, and the relative cerebral blood volume maps were qualitatively and quantitatively analyzed. RESULTS: DWI revealed the majority of the lesions as having increased diffusion within their necrotic centers, with the ADC ranging from 0.5 to 3.01 (mean +/- SD: 1.49 +/- 0.7). All the lesions revealed a predominant lipid peak on MR spectroscopy and were extremely hypovascular on perfusion MR studies. CONCLUSION: MR diffusion, spectroscopy, and perfusion studies help in characterizing toxoplasmosis lesions and, in most cases, can be used in combination to help establish the diagnosis of toxoplasmosis.     

Initial experience with dynamic MR imaging in evaluation of normal bone marrow versus malignant bone marrow infiltrations in humans

The purpose of this study was (a) evaluation of dynamic contrast-enhanced MR imaging of normal bone marrow versus malignant bone marrow infiltrations in patients with proven B-cell-type chronic lymphocytic leukemia (B-CLL) and (b) correlation with the clinical stage according to Binet (stages A, B, C) and response to therapy. Bone marrow imaging of the lumbar spine, pelvis, and proximal femurs was performed at 1.5 T in 45 patients without known malignancy and in 30 patients with B-CLL. The differences between opposed-phase and in-phase dynamic gradient-echo sequences before and up to 10 minutes after intravenous application of .1 mmol/kg body weight of gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) were evaluated in normal bone marrow. The contrast-enhancement patterns of normal and malignant bone marrow were compared using the opposed-phase dynamic gradient-echo sequence. Ten of the patients with bone marrow infiltrations (Binet stage C) additionally underwent MR imaging follow-up during therapy. Opposed-phase gradient echo sequences demonstrated a signal decrease of normal bone marrow, and in-phase gradient echo sequences demonstrated a signal increase of normal bone marrow after administration of Gd-DTPA. The dynamic signal intensity time courses differed significantly (P < .05) between Binet stages B and C and controls as well as among the three Binet stages of B-CLL. In the 10 patients followed during therapy, MR imaging sensitively demonstrated response (n = 6), nonresponse (n = 2), or relapse after initial response (n = 2). In out-of-phase imaging, both normal bone marrow and initial bone marrow infiltration in CLL stage Binet A show signal decrease after administration of contrast agent, whereas there is increase in signal intensity in higher-grade bone marrow infiltration in Binet stage B or C disease. The signal loss of normal bone marrow in out-of-phase imaging is a phase effect rather than a T2* effect. The differentiation of initial from higher-grade bone marrow infiltration on out-of-phase images relies solely on a shift in the fat/water ratio.     

Segmental patterns of avascular necrosis of the femoral heads: early detection with MR imaging

Thirty-two patients (64 hips) in whom avascular necrosis (AVN) of the femoral heads was highly suspected clinically were studied by magnetic resonance (MR) imaging, radionuclide bone scintigraphy, and conventional radiography. MR studies were positive for AVN in 37 hips, compared with 30 positive scintigraphic studies. In all cases in which scintigraphy and radiography were positive, MR imaging demonstrated decreased signal from the affected femoral heads, indicative of bone marrow disease. Imaging results were confirmed by biopsy or subsequent imaging appearances. In patients with negative initial scintigraphic and radiographic studies, the MR imaging criterion for a positive study was a moderately decreased bone marrow signal displaying segmental patterns within an otherwise normal-appearing femoral head on relatively T1-weighted images. In this series of high-risk patients, radionuclide scintigraphy had a sensitivity of 81%, compared with 100% for MR imaging. MR imaging should be the imaging modality of choice for early evaluation of bone marrow changes indicative of AVN.     

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.     

Malignant lymphoma: bone marrow imaging versus biopsy

In 107 patients with malignant Hodgkin and non-Hodgkin lymphoma, bone marrow was evaluated with scintigraphy, magnetic resonance (MR) imaging, and biopsy to detect bone marrow infiltration. Imaging and biopsy results were classified as normal (class 0), suggestive of reactive changes (class 1), or suspicious for infiltration (class 2). About one-half of biopsy and imaging results agreed completely. In patients with chronic lymphocytic leukemia, false-negative findings were frequent with both imaging techniques. Although a positive biopsy result is usually accepted as proof of bone marrow infiltration, results indicate that negative biopsy findings do not exclude tumor involvement. When suspected infiltration was found with MR imaging or scintigraphy but results were normal or suggestive of reactive changes in the first blind biopsy, repeat blind or guided biopsy helped confirm the imaging results. Autopsy findings in two patients completely confirmed previous results with MR imaging and scintigraphy, although findings at antemortem biopsy were different. Scintigraphy and MR imaging should be included routinely in the staging of malignant lymphoma as an adjunct to blind biopsy in the complete evaluation of bone marrow status.     

Bone marrow disorders: characterization with quantitative MR imaging

Thirty patients with various hematologic disorders and 15 healthy control subjects underwent quantitative magnetic resonance (MR) imaging of the lumbar spine with spin-echo techniques. Images of patients with infiltrative bone marrow disorders showed significantly more prolonged T1 times than those of control subjects (P less than .001). It was not possible to distinguish different diffuse infiltrative bone marrow disorders on the basis of T1 values. Aplastic anemia could be distinguished from normality because of significantly shortened T1 (P less than .001). A significant correlation was seen between T1 and bone marrow cellularity (r = .74, P less than .001). T2 was of no value in the characterization of bone marrow disorders. Quantitative MR imaging dose not improve the diagnostic potential of bone marrow imaging in the detection of diffuse marrow infiltrates.     

CT and MRI manifestations of central nervous system infection following allogeneic bone marrow transplantation.

AIM: To determine the frequency, microbiological diversity and radiological patterns of central nervous system (CNS) infection following allogeneic bone marrow transplantation (BMT). PATIENTS AND METHODS: Two neuroradiologists retrospectively reviewed the computed tomography (CT) and magnetic resonance imaging (MRI) examinations of a large cohort of bone marrow recipients. The radiological findings were correlated with clinical, microbiological and pathological data. RESULTS: During an 8-year period 406 patients underwent allogeneic BMT; a total of 11 infections of the CNS were diagnosed in nine patients [sino-orbital aspergillosis (3), cerebral aspergillosis (2), pseudomonas (1), listeria (1), human herpes virus-6 (1), herpes zoster (1), toxoplasmosis (1) and progressive multifocal leucoencephalopathy (1)]. The radiological abnormalities could be divided into one or more of the following pathological entities: (i) focal lesions, (ii) invasive sinusitis, (iii) cerebral infarction, (iv) demyelination, (v) encephalitis and (vi) meningitis/hydrocephalus. CONCLUSIONS: Approximately 2% of bone marrow recipients developed an infection of the CNS. The spectrum of infection changed over time and was related to predictable deficits in host immunity. The radiological appearances were diverse and corresponded to several different pathological processes.     

手及腕关节MRI对类风湿性关节炎的早期诊断价值

目的探讨MRI对类风湿性关节炎的早期诊断价值。方法对76例以多关节痛为主诉的患者行双手及腕关节MR扫描(经随访证实，其中54例为类风湿性关节炎，22例为非类风湿性关节炎)，观察其MRI有无滑膜强化或增厚(包括有无对称性)、骨侵蚀、骨髓水肿、肌腱炎及关节积液等征象，及各种征象对诊断的作用。根据不同MRI征象的出现频率，使用Bayes判别分析的方法尝试寻找类风湿性关节炎的MRI诊断标准。结果本组54例类风湿性关节炎患者中12例为MRI早期诊断。以对称性滑膜强化或增厚为诊断标准时，灵敏度85.19％，特异度86．36％。结论MRI是类风湿性关节炎诊断的可靠手段之一，并可应用于早期诊断。当MRI扫描出现对称性滑膜强化时，高度提示早期类风湿性关节炎的诊断；当对称性滑膜强化或增厚与骨侵蚀、骨髓水肿、肌腱炎、关节积液中的至少任何1项并存，或当非对称性滑膜强化或增厚与上述至少任何2项并存时，应该考虑类风湿性关节炎的诊断。     

Osteodensitometry of human heel bones by MR spin-echo imaging: comparison with MR gradient-echo imaging and quantitative computed tomography

The aim of the study was to investigate whether quantitative magnetic resonance (MR) fast spin-echo (FSE) imaging with moderate spatial resolution enables osteodensitometry in peripheral yellow bone marrow. Signal intensities in T1-weighted FSE images from yellow bone marrow indicate the amount of adipose tissue per volume. The signal intensity in marrow regions with spongy bone was assessed and compared to signal intensity of pure fatty marrow (100%). Heel bones of 30 patients with suspected osteoporosis were analyzed and the FSE images were compared with results from parallel MR gradient-echo (GE) imaging and quantitative computed tomography (QCT) examinations. High correlation was found between FSE imaging and QCT [r = 0.91 in the dorsal region of interest (ROI); r = 0.86 in ventral ROI]. Linear correlation coefficients between GE imaging and QCT were slightly lower in the dorsal part (r = -0.86) and considerably lower in the ventral part (r = -0.68). Correlation between the two MR techniques amounted to r = -0.72/-0.61 (dorsal/ventral). The high correlation between FSE imaging and bone mineral density (BMD) allows possible clinical applications of FSE imaging for diagnosis of osteoporosis. Further improvements of the accuracy using reference phantoms might be possible.     

Hematopoietic reconstitution after bone marrow transplantation: Assessment with MR imaging and H-1 localized spectroscopy

Magnetic resonance (MR) studies were performed in 14 patients as early as possible (21–110 days) after bone marrow transplantation (BMT). MR characteristics of lumbar vertebral bone marrow were studied with T1-weighted spin-echo imaging, water- and fatselective imaging with a frequency-selective excitation technique, and point-resolved spatially localized proton spectroscopy. Signals from water and fat protons and their T1 and T2 values were analyzed. Water proton signal intensity correlated well with cellularity within bone marrow, as determined with parallel iliac crest biopsies. The fraction of signal from water in red bone marrow of patients with allogeneic transplants from siblings (four cases) was significantly higher than in four patients with autologous transplants. The latter showed very low cellularity in the period of about 4 weeks after BMT because of the cytotoxic pretreatment of the bone marrow. The MR results in six patients with allogeneic transplants from unrelated donors ranged widely, depending on the complications after BMT. Analysis of data obtained with the different techniques showed that water- and fat-selective MR imaging and spectroscopic methods are useful for noninvasive monitoring of hematopoietic reconstitution after BMT.     

MR imaging of therapy-induced changes of bone marrow

MR imaging of bone marrow infiltration by hematologic malignancies provides non-invasive assays of bone marrow cellularity and vascularity to supplement the information provided by bone marrow biopsies. This article will review the MR imaging findings of bone marrow infiltration by hematologic malignancies with special focus on treatment effects. MR imaging findings of the bone marrow after radiation therapy and chemotherapy will be described. In addition, changes in bone marrow microcirculation and metabolism after anti-angiogenesis treatment will be reviewed. Finally, new specific imaging techniques for the depiction of regulatory events that control blood vessel growth and cell proliferation will be discussed. Future developments are directed to yield comprehensive information about bone marrow structure, function and microenvironment.     

Imaging of bone marrow disease in the spine

Bone marrow imaging has been greatly advanced with magnetic resonance (MR) imaging. Bone marrow contains fat and nonfat cells, which makes imaging with MR imaging the modality of choice, particularly within the spine. Any alteration within the marrow makeup is usually well seen with different MR imaging sequences. Conventional spin-echo sequences are helpful because of their great signal-to-noise ratio, and anatomic detail. Other, newer sequences--such as short T1 inversion recovery (STIR), diffusion weighted, fat suppression techniques; as well as in- and opposed-phase images--may also help to increase detection of or characterize certain diseases of the bone marrow within the spine. This article deals with the different imaging sequences available to radiologists when imaging the spinal bone marrow.     

Magnetic resonance appearance of uncomplicated Paget's disease of bone

Paget's disease is a disorder of the bone mesenchyma of the skeleton and is a unique condition in which active bone changes can occur without concomitant significant marrow alteration. When present, marrow changes involve predominantly the paratrabecular and endosteal areas, where bone metabolism is increased. At magnetic resonance (MR) imaging, marrow alterations can become prominent and hence confusing in bones with high trabecular content including vertebrae and pelvis. This article addresses the MR appearance of uncomplicated Paget's disease, including normal pagetic bone, predominantly lytic or sclerotic pagetic bone, and unusual partial involvement of the vertebral body. We will emphasize the added diagnostic value of the combination of imaging techniques that depict either osseous changes including radiographs, computed tomography, and bone scintigraphy, or marrow changes, including MR imaging, to contribute to a noninvasive presumptive diagnosis of Paget's disease in atypical presentations.     

Whole-body MR imaging for detection of bone metastases in children and young adults: comparison with skeletal scintigraphy and FDG PET.

OBJECTIVE: The purpose of this study was to compare the diagnostic accuracy of whole-body MR imaging, skeletal scintigraphy, and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for the detection of bone metastases in children. SUBJECTS AND METHODS: Thirty-nine children and young adults who were 2--19 years old and who had Ewing's sarcoma, osteosarcoma, lymphoma, rhabdomyosarcoma, melanoma, and Langerhans' cell histiocytosis underwent whole-body spin-echo MR imaging, skeletal scintigraphy, and FDG PET for the initial staging of bone marrow metastases. The number and location of bone and bone marrow lesions diagnosed with each imaging modality were correlated with biopsy and clinical follow-up as the standard of reference. RESULTS: Twenty-one patients exhibited 51 bone metastases. Sensitivities for the detection of bone metastases were 90% for FDG PET, 82% for whole-body MR imaging, and 71% for skeletal scintigraphy; these data were significantly different (p < 0.05). False-negative lesions were different for the three imaging modalities, mainly depending on lesion location. Most false-positive lesions were diagnosed using FDG PET. CONCLUSION: Whole-body MR imaging has a higher sensitivity than skeletal scintigraphy for the detection of bone marrow metastases but a lower sensitivity than FDG PET.