Magnetic resonance imaging of normal bone marrow

The appearance in magnetic resonance imaging (MRI) of the bones depends, to a large extent, on the unmineralized content of the bone cavities. Because yellow marrow contains a large number of fat protons and red marrow a significant number of water protons, MRI offers the opportunity to map the distribution of red and yellow marrow. In addition, red marrow MR appearance varies according to the relative proportion of fat and nonfat cells. Variations in the composition of red marrow and its distribution among normal subjects, mainly in relation to age and sex, contribute to creating a wide spectrum in bone MR appearance, which must be known in order to avoid confusion with bone marrow abnormalities. Received 22 May 1997; Revision received 27 January 1998; Accepted 29 January 1998     

Structural and functional imaging of normal bone marrow and evaluation of its age-related changes

A number of noninvasive imaging techniques have been used for the evaluation of bone marrow, including magnetic resonance imaging (MRI) and bone marrow scintigraphy. The appearance of bone marrow on MRI varies considerably depending on the proportion of red and yellow marrow, and the composition of the red marrow and its distribution with relation to age and sex. The composition of bone marrow also can vary under physiological and pathological conditions. MRI is a highly sensitive technique for evaluating the bone marrow, but it is limited in its practical use for whole-body bone marrow screening. Bone marrow scintigraphy with radiolabeled compounds such as technetium-99m-labeled nanocolloid and monoclonal antibodies has the advantage of evaluating the entire bone marrow, and has been used for the diagnosis of various bone marrow disorders. In addition, (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging can be used to evaluate bone marrow metabolism and disease and to provide information about the state of the primary tumor, lymph nodes, and distant metastases. Understanding of the appearance of normal bone marrow, including age- and sex-specific differences with each of these imaging modalities, is essential to permit accurate diagnosis of benign and malignant bone marrow disorders. We present a review of MRI and scintigraphy of normal bone marrow with some emphasis on FDG-PET imaging in assessing marrow activity in normal and abnormal states and also present preliminary data regarding normal age-related changes in bone marrow through use of FDG-PET, as well as the role of segmentation of bone marrow on MRI for quantitative calculation of the metabolic volumetric product for red marrow metabolism using FDG-PET.     

Magnetic resonance of the bone marrow

Magnetic resonance imaging has opened new possibilities to current diagnostic radiology in the evaluation of bone marrow. In the past, bone marrow imaging was based on conventional radiology, nuclear medicine and computed tomography; they all exhibited some capabilities but also some limitations. Bone image on MR scans is due to bone marrow, with its different components of red and yellow marrow. Since red marrow is mostly liquid and yellow marrow contains large amounts of fat, the signal will vary, on T1-weighted images, according to their different proportions. There is a gradual change from red marrow to yellow marrow from birth to adulthood: this change determines the MR appearance of bone marrow, the different features of which should be known for a correct evaluation of pathologic findings. MRI is extremely effective in the evaluation of infiltrative disorders of bone marrow, such as leukemia, lymphoma, myeloma, primary and metastatic skeletal tumors, and infections. MRI allows depletive disorders of bone marrow and ischemic processes to be studied. Finally, MRI allows the non-invasive follow up of bone marrow pathologic conditions, thus representing a valid alternative to biopsy.     

Bone marrow investigation with technetium-99m microcolloid and magnetic resonance imaging in patients with malignant myelolympho-proliferative diseases

In 63 patients with primary extramedullary malignant lymphoma or plasmacytoma, a study was performed in order to evaluate bone marrow involvement. All patients underwent a ^99mTc microcolloid bone marrow whole body imaging (scintigraphy), using a gamma camera interfaced with a computer, followed by nuclear magnetic resonance bone marrow imaging (MRI), (1.5 Tesla). MR images were made of the lumbosacral region, the pelvic region, both femoral and other parts of the skeleton, according to focal lesions in the scintigraphy. A posterior iliac crest bone marrow biopsy was used as a standard reference. In the present study, both scintigraphy and MRI showed a dissiminated or focal involvement or a combination of both. In 53 of the 63 patients (84%) the results were in accordance. Pathological MR signals or pathological findings in scintigraphy did not always correspond to tumorous bone marrow involvement, and were shown to reflect reactive changes in the central part of the skeleton in combination with a periphery radionuclide extention interpreted as a periphery compensatory hematopoetic proliferation. The negative predictive value of scintigraphy and MRI was 92% and 100%, respectively. When combining the results of both examinations, the positive predictive value increased from 49% to 58%, if the bone marrow biopsy is accepted as gold standard. The results indicate that bone marrow investigation performed simultaneously using scintigraphy and MRI is superior both to the use of either of the methods alone and to the traditional iliac crest bone marrow biopsy.     

MRI and CT evaluation of primary bone and soft-tissue tumors

Twenty-six patients with primary tumors of bone or somatic soft tissues underwent both magnetic resonance imaging (MRI) and computed tomography (CT); 15 of the patients had radionuclide bone scans as well. Only in a minority of cases did these tomographic methods provide information needed for diagnosis that could not be derived from the plain radiographs alone; however, for assessing the extent of the disease, both CT and MRI proved very valuable, particularly MRI. Specifically, MRI was superior to CT in delineating the extent of the neoplasms and their relation to surrounding structures in 21 of the patients, equal in four, and inferior in only one. Furthermore, in the 13 patients with tumors of long bone, MRI was judged superior to CT in visualizing marrow abnormality in 12 cases, and equal in only one case. Radionuclide scans demonstrated the lesions in 14 of the 15 cases; its primary utility was in excluding additional lesions. It is concluded that for these patients, MRI was the imaging method of choice in assessing the extent of bone and soft-tissue tumors.     

Bone scintigraphy and magnetic resonance imaging after transtrochanteric rotational osteotomy

Objective. To assess the ability of bone scintigraphy and magnetic resonance imaging (MRI) to predict the outcome of transtrochanteric rotational osteotomy (TRO) for osteonecrosis of the femoral head (ONFH). Design. This study was a prospective evaluation of imaging techniques. Patients and methods. MRI and bone scintigraphy were performed on 20 hips in 18 patients at 3 months after TRO. The radiographic findings at 3 months after TRO, and the MRI and bone scintigraphic findings, were compared with the radiographic findings at final follow-up (mean 39 months). Results and conclusions. On MRI a low-intensity area or a low-intensity band in the new weight-bearing area extending over the acetabular edge on T1-weighted images was related to the presence of collapse on the radiographs at final follow-up. In hips with an area of absent activity in the new weight-bearing surface on bone scintigraphy, collapse was seen more frequently on radiographs at final follow-up than in hips without this feature. Bone scintigraphy was no more specific than radiography in predicting the outcome after TRO. We consider MRI to be superior to bone scintigraphy in predicting the occurrence of collapse, which is one of the major short-term problems after TRO. Received: 22 July 1997 Revision requested: 2 January 1998, 12 October 1998 Revision received: 3 March 1998, 23 December 1998 Accepted: 18 January 1999     

The evolving role of MRI in oncohaematological disorders

Magnetic resonance imaging (MRI) has opened new possibilities to current diagnostic radiology in the evaluation of bone marrow. Compared with other imaging modalities, MRI is the only technique able to directly visualise bone marrow with its different components of red and yellow marrow. Other advantages of MRI are high-contrast resolution and multiplanar view, as well as extensive coverage of the skeleton with whole-body MRI (WBMRI). However, specificity of signal alterations of bone marrow is low. Therefore, MRI findings need to be integrated with clinical and laboratory findings as well as with haematological and oncological evaluation. MRI provides information that effectively aids diagnosis, staging and follow-up of various bone marrow disorders. There is increasing interest in the capabilities of MRI in the evaluation of bone marrow, in particular of haematological malignancies. According to some authors much work remains to be done to improve sensitivity and specificity of MRI in order to define the real clinical value of this imaging modality in the multidisciplinary management of patients with a haematological malignancy. This article presents recent developments and perspectives in the use of MRI in oncohaematological diseases.     

Bone marrow investigation with technetium-99m microcolloid and magnetic resonance imaging in patients with malignant myelolympho-proliferative diseases

In 63 patients with primary extramedullary malignant lymphoma or plasmacytoma, a study was performed in order to evaluate bone marrow involvement. All patients underwent a 99mTc microcolloid bone marrow whole body imaging (scintigraphy), using a gamma camera interfaced with a computer, followed by nuclear magnetic resonance bone marrow imaging (MRI), (1.5 Tesla). MR images were made of the lumbosacral region, the pelvic region, both femoral and other parts of the skeleton, according to focal lesions in the scintigraphy. A posterior iliac crest bone marrow biopsy was used as a standard reference. In the present study, both scintigraphy and MRI showed a dissiminated or focal involvement or a combination of both. In 53 of the 63 patients (84%) the results were in accordance. Pathological MR signals or pathological findings in scintigraphy did not always correspond to tumorous bone marrow involvement, and were shown to reflect reactive changes in the central part of the skeleton in combination with a periphery radionuclide extention interpreted as a periphery compensatory hematopoietic proliferation. The negative predictive value of scintigraphy and MRI was 92% and 100%, respectively. When combining the results of both examinations, the positive predictive value increased from 49% to 58%, if the bone marrow biopsy is accepted as gold standard. The results indicate that bone marrow investigation performed simultaneously using scintigraphy and MRI is superior both to the use of either of the methods alone and to the traditional iliac crest bone marrow biopsy.     

The value of bone scintigraphy,bone marrow scintigraphy and fast spin-echo magnetic resonance imaging in staging of patients with malignant solid tumours: a prospective study

The purpose of this prospective study was to define the value of bone scintigraphy (BS), bone marrow scintigraphy (BMS) and the new fast spin-echo (FSE) magnetic resonance imaging (MRI) sequences in screening for bone metastases in patients with solid malignant tumours. It was our particular interest to classify patients into a group with and a group without bone metastases, and not only to compare the absolute number of metastases detected by each method. Thirty-two patients were examined using technetium-99m dicarboxy propane diphosphonate bone scintigraphy, ^99mTc-labelled monoclonal anti-granulocyte antibodies for bone marrow scintigraphy and 1.5 T MRI using T1-weighted and FSE T2-weighted sequences. Against a reference standard obtained by re-evaluation of all clinical and imaging data 1 year after prospective BS, BMS and MRI had been performed, the three imaging modalities were falsely positive in two, eight and two cases and falsely negative in zero and four cases, respectively. BMS was falsely positive in eight patients because of vertebral marrow degeneration which caused photopenic defects which could not be differentiated from metastases. MRI showed these lesions to unequivocally contain fat. BMS and MRI were falsely negative in four cases because of the limited field of examination. In our study the key factor in classifying a patient as bone MI or MO was the possibility of surveying the entire skeleton, as is the case in BS, and not that MRI had a higher sensitivity compared to BS when analysis was on a lesion-by-lesion basis. BMS had the same limitations as MRI because the usual bone marrow distribution resulted in a physiologically limited field of view. We conclude that BS remains the method of choice in staging patients with solid tumours despite the fact that MRI is no longer a time-consuming method using FSE sequences. MRI has a complemantary role if special questions remain. BMS appears to have little value in the detection of bone metastases because of its poor specificity, its limited spatial resolution and its restriction to those areas of the skeleton containing haematopoietic marrow. Correspondence to: G.K. v. Schulthess     

Systemic mastocytosis: MRI of bone marrow involvement

Systemic mastocytosis (SM) is an abnormal proliferation of mast cells, located in different structures: skin, bone marrow, spleen, liver and lymph nodes. Magnetic resonance imaging was prospectively performed in ten patients diagnosed by bone marrow biopsy in order to describe the different patterns of bone marrow involvement. Coronal T1-weighted spin-echo images were obtained in vertebral, pelvic, humeral and femoral bones. Depending on the extension of the cell infiltration, three patterns of bone marrow involvement were used: normal/no involvement (N), non-homogeneous (NH) and homogeneous (H). All ten patients presented bone infiltration. The patterns observed were: spine (50 % NH, 50 % H), pelvis (70 % NH), humerus 100(NH) and femur 40 % (NH). T1-weighted MR imaging is a sensitive technique for detecting marrow abnormalities in patients with systemic mastocytosis. There is no correlation between percentage of mast cells in bone marrow biopsy and extent or pattern of bone marrow involvement. Received: 5 June 1998; Revision received: 23 November 1998; Accepted: 15 January 1999     

Prevalence of spontaneous osteonecrosis of the medial femoral condyle in elderly patients

Aseptic osteonecrosis of the medial femoral condyle has recently been reported as a complication of arthroscopic surgery. The time interval between the onset of symptoms and pathognomonic MRI changes (diagnostic window) is not known for osteonecrosis of the knee. To determine the prevalence of early-stage spontaneous osteonecrosis of the knee (SONK) we prospectively examined 176 patients by MRI between May 1998 and December 1999. In six patients MRI revealed a bone marrow edema pattern and subtle subchondral bone changes in the medial condyle consistent with early-stage SONK (prevalence of 3.4%); in the 53 patients older than 65 years the prevalence was 9.4%. In 10 patients (5.7%) the bone and marrow changes on MRI imaging either resolved on follow-up MRI and were regarded as transient epiphyseal lesions or were considered to be reactive changes due to underlying degenerative articular disease. Including MRI in the preoperative diagnostic procedures could avoid missing the diagnosis of avascular necrosis before planning an operative treatment of suspected meniscal tears in elderly patients.     

Magnetic resonance imaging of bone marrow disorders

The sensitivity of MRI to marrow infiltration together with the ability to perform multiplanar imaging allows evaluation of the bone marrow in a manner that has never been feasible before. The clinical impact of this has yet to be fully realized. However, detection of focal marrow infiltration by MRI with concurrently normal conventional imaging studies has important clinical implications for staging and therapy. Proper staging of marrow-based neoplasms such as leukemia and lymphoma is fundamental to the determination of treatment and prognosis. MRI can be used to increase diagnostic certainty when a question exists concerning primary or metastatic marrow disease when other imaging studies are inconclusive. Chemical shift imaging may further improve the sensitivity and clinical utility of magnetic resonance imaging in patients with hematologic disorders involving the bone marrow.     

Vertebral involvement in SAPHO syndrome: MRI findings

We report on the MRI findings in the vertebrae and surrounding soft tissues in two patients with the SAPHO syndrome (Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis). The MRI findings include abnormal bone marrow signal, either focal or diffuse, of the vertebral bodies and posterior elements; hyperintense paravertebral soft tissue swelling and abnormal signal of the intervertebral discs. These changes are consistent with discitis and osteitis. Received: 27 July 1998 Revision requested: 14 October 1998 Revision received: 23 November 1998 Accepted: 24 November 1998     

淋巴瘤骨髓的MRI表现

目的：研究骨淋巴瘤的MRI表现,探讨其MRI诊断的价值。方法：10例骨淋巴瘤,男8例,女2例,年龄11－75岁,平均35．6岁。10例均行MRI检查,原发性霍奇金病（Hodgkin‘s disease,HD)和非霍奇金淋巴瘤（non-Hogkin‘s lymphoma,NHL)各1例,继发性B细胞源性NHL8例。结果（1）发病部位：8例继发性者累及腰椎6例次,胸椎5例次,骶尾椎4例次,骨盆3例次,股骨近端、肋骨、颅骨、胸骨各1例次。2例原发性HD和NHL分别累及胸腰椎和胸椎;(2)病灶数目;8例继发性者均多骨多发,2例原发性HD和NHL分别为多骨多发和单骨发病;（3）MRI信号：骨髓异常表现为长T1长T2信号,软组织肿块表现为等T1、略长T2信号;（4）病灶形态;9例呈多发灶状、斑片状态改变,1例原发生HD呈弥漫性改变;（5）病理性骨折及软组织肿块;3例合并椎体病理性骨折,6例合并软组织肿块,结论：骨淋巴瘤以继发性NHL为主,主要侵犯中轴骨,多呈多局灶性,斑片状长T1、长T2信号。MRI检查敏性高,但缺乏特异性。     

MRI of bone marrow

MRI can visualize bone marrow more clearly than X-CT or RI because the bone generates weak signals whereas the fat in the marrow gives strong signals. We described diagnosis of various bone marrow disorders by MRI technique. Hyperplasia of bone marrow decreased fatty cells and resulted in prolongation of T1, whereas hypoplasia of bone marrow replaced hematopoietic cells with fatty cells and resulted in shortening of T1. In aplastic anemia, the localized hyperplastic areas in abnormal fatty marrow can be visualized. In bone tumor and metastasis to bone marrow, T1-weighted IR image can provide the best contrast between the tumor and normal marrow, although neoplastic and inflammatory lesions can not be differentiated by MRI. In iron storage diseases, MRI can detect early changes by its higher sensitivity to iron than that of X-CT. MRI may be usefull in monitoring bone marrow damages noninvasively to patients under radiation and/or anticancer drug therapy.     

Diffusion-weighted imaging (DWI) in musculoskeletal MRI: a critical review

Magnetic resonance imaging (MRI) is the mainstay of diagnosis, staging and follow-up of much musculoskeletal pathology. Diffusion-weighted magnetic resonance imaging (DWI) is a recent addition to the MR sequences conventionally employed. DWI provides qualitative and quantitative functional information concerning the microscopic movements of water at the cellular level. A number of musculoskeletal disorders have been evaluated by DWI, including vertebral fractures, bone marrow infection, bone marrow malignancy, primary bone and soft tissue tumours; post-treatment follow-up has also been assessed. Differentiation between benign and malignant vertebral fractures by DWI and monitoring of therapy response have shown excellent results. However, in other pathologies, such as primary soft tissue tumours, DWI data have been inconclusive in some cases, contributing little additional information beyond that gained from conventional MR sequences. The aim of this article is to critically review the current literature on the contribution of DWI to musculoskeletal MRI.     

多层螺旋CT联合磁共振成像在踝关节处隐匿性骨折中的诊断价值

目的探讨踝关节处隐匿性骨折的多层螺旋CT(MSCT)和磁共振成像(MRI)诊断价值。方法选取踝关节处隐匿性骨折患者61例,对所有患者的MSCT和MRI资料进行回顾性分析。结果MSCT联合MRI诊断出踝关节处隐匿性骨折59例,检出率为96.7%;MRI诊断51例,检出率为83.6%,主要表现为受累骨内骨髓不规则片状异常信号,T1WI呈低信号,T2WI呈高信号或略高信号,脂肪抑制序列表现为高信号或者混杂高信号;MSCT诊断41例,检出率为67.2%,主要表现为骨皮质、骨小梁的断裂以及微小骨撕脱等。三种检查方法之间比较P<0.05,差异有统计学意义,组间两两对比P<0.05,差异有统计学意义。结论MSCT和MRI对踝关节处隐匿性骨折均具有较高的诊断价值,二者联合检出率最高。     

Magnetic resonance imaging of the wrist: Bone and cartilage injury

Magnetic resonance imaging (MRI) is particularly useful for imaging the wrist due to its superior soft tissue contrast and ability to detect subtle bone marrow changes and occult fractures. A high field (1.5T or greater) strength, dedicated wrist coil, and high in‐plane and through‐plane resolution must be utilized to successfully visualize the relatively thin cartilage of the wrist. MRI can be used to detect occult carpal bone fractures, identify complications following scaphoid fractures, and assess for avascular necrosis in the setting in Kienböck's and Preiser's disease. MRI is useful to identify secondary soft tissue and chondral pathology in impaction/impingement syndromes. The use of an intermediate‐echo time fast spin echo sequence allows for accurate assessment of articular cartilage, allowing evaluation of chondral wear in the setting of primary osteoarthritis and posttraumatic degenerative arthrosis. MRI is the most sensitive imaging modality for the detection of early inflammatory arthropathies and can detect synovitis, bone marrow edema, and early erosions in the setting of negative radiographs. J. Magn. Reson. Imaging 2013;37:1005–1019. © 2012 Wiley Periodicals, Inc.     

Iron-oxide-enhanced MR imaging of bone marrow in patients with non-Hodgkin's lymphoma: differentiation between tumor infiltration and hypercellular bone marrow

The aim of this study was to differentiate normal, hypercellular, and neoplastic bone marrow based on its MR enhancement after intravenous administration of superparamagnetic iron oxides in patients with cancer of the hematopoietic system. Eighteen patients with cancer of the hematopoietic system underwent MRI of the spine before and after infusion of ferumoxides ( n=9) and ferumoxtran ( n=9) using T1- and T2-weighted turbo spin-echo (TSE) and short tau inversion recovery sequences (STIR). In all patients diffuse or multifocal bone marrow infiltration was suspected, based on iliac crest biopsy and imaging such as conventional radiographs, MRI, and positron emission tomography. In addition, all patients had a therapy-induced normocellular ( n=7) or hypercellular ( n=11) reconversion of the normal non-neoplastic bone marrow. The MRI data were analyzed by measuring pre- and post-contrast signal intensities (SI) of hematopoietic and neoplastic marrow and by calculating the enhancement as deltaSI(%) data and the tumor-to-bone-marrow contrast as contrast-to-noise ratios (CNR). Changes in bone marrow signal intensity after iron oxide administration were more pronounced on STIR images as compared with T1- and T2-weighted TSE images. The STIR images showed a strong signal decline of normal and hypercellular marrow 45-60 min after iron oxide infusion, but no or only a minor signal decline of neoplastic bone marrow lesions; thus, deltaSI% data were significantly higher in normal and hypercellular reconverted marrow compared with neoplastic bone marrow lesions ( p<0.05). Additionally, the contrast between focal or multifocal neoplastic bone marrow infiltration and normal bone marrow, quantified by CNR data, increased significantly on post-contrast STIR images compared with precontrast images ( p<0.05). Superparamagnetic iron oxides are taken up by normal and hypercellular reconverted bone marrow, but not by neoplastic bone marrow lesions, thereby providing significantly different enhancement patterns on T2-weighted MR images; thus, superparamagnetic iron oxides are useful to differentiate normal and neoplastic bone marrow and to increase the bone marrow-to-tumor contrast.     

Magnetic resonance tomography of the bone marrow for the detection of metastases of solid tumors]

The bone marrow is a common site of metastases in patients with solid tumors. Metastatic bone marrow involvement is found much more frequently at autopsy than in routine staging procedures. The purpose of this study was to evaluate the diagnostic efficacy of bone marrow MRI in such patients, and especially in those with small cell lung cancer and female breast carcinoma. MRI is a fast and reliable method for the early detection of bone marrow metastases in patients with carcinoma. In many studies and according to our own experience, it is much more sensitive than radionuclide bone scan, iliac crest biopsy and plain film radiography. However, a clear clinical benefit of its use in the initial staging has so far been proven only for patients with small cell lung cancer. As a consequence, MRI should be applied for the staging of solid tumors only when clinical examination does not yield unambiguous results. Owing to its superiority to biopsy and bone scan, bone marrow MRI should become an integral part of the initial staging procedure in small cell lung cancer and wherever it is sufficiently available it can replace the conventional diagnostic procedures.