Differential diagnosis of focal and diffuse neoplastic diseases of bone marrow in MRI

Magnetic resonance imaging (MRI) has become the preferred imaging modality for the evaluation of malignant disease in the bone marrow. Compared to bone marrow aspiration and biopsy, MRI is noninvasive and provides information by sampling a large volume of bone marrow. Due to disease-related alterations in the composition of bone marrow, MRI provides a very high sensitivity, but lacks specificity for most bone marrow disorders. However, MRI can be a very valuable diagnostic tool properly placed within the clinical context.     

Chronische Infektionen des Skelettsystems Bildgebende Diagnostik

The diagnosis of chronic osteomyelitis is made on the basis of clinical, radiologic and histologic findings. The role of imaging in patients with known chronic osteomyelitis is to detect and to delineate areas of active infection. To correctly interpret the imaging findings, it is essential to take both the individual clinical findings and previous imaging studies into account. Reliable signs of active infection are bone marrow abscess, sequestra and sinus tract formation. Only the combined evaluation of bony changes together with alterations of the adjacent soft tissues provides good diagnostic accuracy. Projection radiography gives an overview of the condition of the bone, which provides the basis for follow-up and the selection of further imaging modalities. Computed tomography can be used to evaluate even discrete or complex bony alterations and to guide percutaneous biopsy or drainage. Magnetic resonance imaging achieves the best diagnostic sensitivity and specificity and provides superior contrast as well as anatomical resolution in both bone marrow and soft tissues. In this paper the features and clinical relevance of imaging in primary chronic osteomyelitis, posttraumatic osteomyelitis, tuberculous spondylitis and osteomyelitis of the diabetic foot are reviewed, with particular respect to MRI.     

Bone marrow changes in osteoarthritis

Magnetic resonance imaging (MRI) is gaining increasing significance to study disease burden and progression in osteoarthritis. Bone marrow edema pattern has been identified as a typical MR finding associated with osteoarthritis. Histologically, bone marrow edema pattern is characterized by a mix of different pathologies, including bone marrow necrosis, fibrosis, microfractures, and bone remodeling as well as fibrovascular ingrowth. On MR imaging, bone marrow edema pattern is typically associated with subchondral cysts, cartilage defects, and meniscal degeneration; prevalence and size correlates with disease severity. Bone marrow edema pattern may be found in association with other abnormalities such as subchondral insufficiency fractures. Clinically the significance of bone marrow edema is controversially discussed with some studies showing evidence of associated pain. In summary, bone marrow signal abnormalities are frequent MRI signs of osteoarthritis with different histological findings, typical associated abnormalities, and also clinical significance.     

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.     

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.     

Magnetic resonance imaging of the bone marrow in hematological malignancies

Despite its lack of specificity, magnetic resonance imaging (MRI) of the bone marrow has the potential to play a role in the management of patients with primary neoplastic disorders of the hematopoietic system, including lymphomas, leukemias and multiple myeloma. In addition to its use in the assessment of suspected spinal cord compression, bone marrow MRI could be used as a prognostic method or as a technique to assess the response to treatment. The current review addresses the common patterns of bone marrow involvement observed in primary neoplasms of the bone marrow, basic technical principles of bone marrow MRI, and several applications of MRI in selected clinical situations. 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.     

Spleen in haematological malignancies: spectrum of imaging findings

Imaging morphology and metabolic activity of splenic lesions is of paramount importance in patients with haematological malignancies; it can alter tumour staging, treatment protocols and overall prognosis. CT, MRI and positron emission tomography (PET)/CT have been shown to be powerful tools for the non-invasive assessment of splenic involvement in various haematological malignancies. Since many haematological malignancies and non-neoplastic conditions can involve the spleen and imaging manifestations can overlap, imaging and clinical findings outside of the spleen should be looked for to narrow the differential diagnosis; confirmation can be obtained by pathological findings. Radiologists should be familiar with the cross-sectional imaging patterns of haematological malignancies involving the spleen as well as non-neoplastic splenic findings common in these patients to facilitate their care and follow-up. This pictorial review provides the common and uncommon imaging appearances and complications of various haematological malignancies involving the spleen on CT, MRI and PET/CT, and common pitfalls in diagnosis.     

Bone marrow changes in stress injuries

Stress injuries and associated bone marrow changes are a common finding in athletes of all levels. Magnetic resonance imaging (MRI) is the imaging modality of choice for detecting characterizing and staging these injuries. However, because bone marrow edema patterns may also be seen in asymptomatic athletes, it is imperative for the sports medicine physician and the radiologist to closely correlate the imaging findings with the clinical signs and symptoms to assess the clinical significance of the imaging findings. This article reviews the pathophysiology, MRI findings, and clinical implications of stress injuries in athletes.     

Incidence of pubic bone marrow oedema in Australian rules football players: relation to groin pain

OBJECTIVES: To examine the relation between the clinical features of groin pain and groin magnetic resonance imaging (MRI) appearances in a group largely comprising elite Australian Rules football players. The incidence of bone marrow oedema and other MRI findings in the pubic symphysis region was noted. The relation between a past history of groin pain and these other MRI findings was also examined. METHOD: In a prospective study, 116 male subjects (89 footballers, 17 umpires, 10 sedentary men) were examined before history taking and groin MRI. The clinical history was not known to the examiner (GMV) and radiologists (JPS, GTF). Clinical evidence of groin pain and examination findings were correlated with the presence of increased signal intensity within the pubic bone marrow. A past history of groin pain was correlated with the presence of other MRI findings such as cyst formation, fluid signal within the pubic symphysis disc, and irregularity of the pubic symphysis. RESULTS: Fifty two athletes (47 footballers, five umpires) had clinical features of groin pain with pubic symphysis and/or superior pubic ramus tenderness. A high incidence of increased signal intensity (77%) within the pubic bone marrow was identified in this group. There was an association between this group of athletes and the MRI finding of increased signal intensity (p<0.01). There was also an association between a past history of groin pain and the presence of other MRI findings (p<0.01). CONCLUSIONS: Athletes with groin pain and tenderness of the pubic symphysis and/or superior pubic ramus have clinical features consistent with the diagnosis of osteitis pubis. The increased signal intensity seen on MRI is due to pubic bone marrow oedema. An association exists between the clinical features of osteitis pubis and the MRI finding of pubic bone marrow oedema. A high incidence of pubic bone marrow oedema was also noted. Degenerative features visualised by MRI, such as subchondral cyst formation, were associated with a past history of groin pain. A stress injury to the pubic bone is the most likely explanation for these MRI findings and may be the cause of the clinical entity osteitis pubis.     

A prospective study on MRI findings and prognostic factors in athletes with MTSS

In medial tibial stress syndrome (MTSS) bone marrow and periosteal edema of the tibia on the magnetic resonance imaging (MRI) is frequently reported. The relationship between these MRI findings and recovery has not been previously studied. This prospective study describes MRI findings of 52 athletes with MTSS. Baseline characteristics were recorded and recovery was related to these parameters and MRI findings to examine for prognostic factors. Results showed that 43.5% of the symptomatic legs showed bone marrow or periosteal edema. Absence of periosteal and bone marrow edema on MRI was associated with longer recovery (P = 0.033 and P = 0.013). A clinical scoring system for sports activity (SARS score) was significantly higher in the presence of bone marrow edema (P = 0.027). When clinical scoring systems (SARS score and the Lower Extremity Functional Scale) were combined in a model, time to recovery could be predicted substantially (explaining 54% of variance, P = 0.006). In conclusion, in athletes with MTSS, bone marrow or periosteal edema is seen on MRI in 43,5% of the symptomatic legs. Furthermore, periosteal and bone marrow edema on MRI and clinical scoring systems are prognostic factors. Future studies should focus on MRI findings in symptomatic MTSS and compare these with a matched control group.     

Comparative diagnostic value and therapeutic relevance of magnetic resonance imaging and bone marrow scintigraphy in patients with metastatic solid tumors of the axial skeleton

PURPOSE: To evaluate the comparative impact of magnetic resonance imaging (MRI) and bone marrow scintigraphy (BMS) in bone marrow metastases of solid tumors. METHODS: In 20 patients with solid tumors MRI of the axial skeleton and whole-body BMS were retrospectively reviewed. Detectability of metastases, extent of disease and therapeutic implications were assessed. RESULTS: In 15/20 (75%) patients MRI and BMS concordantly revealed bone marrow metastases of the axial skeleton. In nine of these 15 patients (60%) MRI showed more metastases. Local radiotherapy or surgery was performed in seven of these cases (78%). BMS detected additional metastases of the appendicular skeleton in 8/15 (53%) patients. In 4/20 cases (20%) the imaging findings were discordant. In three patients with degenerative changes (n=2) or lipoma (n=1) BMS was false positive. In another patient BMS failed to detect metastases proven by MRI and clinical follow-up resulting in subsequent radiation therapy. One patient had normal bone marrow. CONCLUSION: MRI appears to be more sensitive and specific in the detection of bone marrow metastases in the axial skeleton and is of clinical importance for subsequent local therapy.     

MR imaging in adults with Gaucher disease type I: evaluation of marrow involvement and disease activity

An investigation was conducted to determine the usefulness of magnetic resonance imaging (MRI) in the evaluation of bone marrow involvement in patients with Gaucher disease type I. T1- and T2-weighted images were obtained of the lower extremities of 29 adult patients. Patients were classified into one of three groups based on marrow signal patterns on T1- and T2-weighted images as well as change in signal intensity from T1- to T2-weighted images. An increase in signal intensity from T1- to T2-weighted images was the criterion for an active process within the bone marrow. Classification of the 29 patients produced the following results: group A: normal, 4 patients; group B: marrow infiltration, 16 patients; group C: marrow infiltration plus active marrow process, 9 patients. Correlation with clinical findings revealed that all nine patients with evidence of an active marrow process on MRI (group C) had acute bone pain. Conversely, only one of the remaining 20 patients (groups A and B) had bone pain. There was no correlation between disease activity and findings on conventional radiographs. We conclude the MRI provides an excellent noninvasive assessment of the extent and activity of marrow involvement in type I Gaucher disease.     

Aplicaciones de la técnica de difusión por resonancia magnética en el manejo de la patología tumoral osteomuscular

Magnetic resonance imaging (MRI) is the technique of choice in the diagnosis, staging, and follow-up of musculoskeletal tumors. Diffusion imaging is a new functional MRI technique that provides information that is complementary to that obtained in conventional MRI sequences. Diffusion imaging has proven useful in different clinical situations like the characterization of disease involving the bone marrow (bone metastases, benign fractures, or hematological disease), the evaluation of tumors of the bones and soft tissues, and the monitoring of the response to treatment in patients with tumors. The aim of this article is to review the diffusion technique in MRI and its current clinical applications in the management of musculoskeletal tumors.     

Imaging in multiple myeloma

In multiple myeloma, imaging is required to determine the stage of disease and to anticipate impending bone fractures. Whereas the traditionally used Durie and Salmon staging system includes lytic bone lesions in plain films as criteria, modern systems include MRI findings. MRI is most sensitive to both diffuse bone marrow involvement as well as solid plasma cell tumors. Whole-body low-dose CT (WBCT) may replace plain films in the near future, since it is quicker, more sensitive and is better tolerated by patients. Intramedullary lesions are well seen as long as they are located in long bones where they are surrounded by fat. Diffuse bone marrow infiltration as well as intravertebral lesions, however, are difficult to detect with WBCT in the absence of frank destruction of cancellous bone. PET or PET-CT with 18-fluoro-deoxyglucose (FDG) are insensitive to diffuse bone marrow infiltration, but may help to assess treatment response in solitary or multiple solid plasma cell tumors which have a high FDG uptake before treatment.     

Postoperative Bildgebung der Nasennebenhöhlen

The radiological interpretation of postoperative changes of the paranasal sinuses requires knowledge of why and how the surgical intervention was performed and what the basic clinical findings were. It is important to know whether there was an inflammation, a reconstructive procedure, or a tumorous process. Multidetector computed tomography (MDCT) evaluated in a high-resolution bone window level setting represents the method of choice for imaging after nonfunctional and functional procedures after inflammatory changes as well as for imaging after reconstructive surgery because of facial trauma or before dental implantation. In the postoperative follow-up of tumor patients contrast-enhanced MDCT evaluated in a soft tissue window and bone window and especially magnetic resonance imaging (MRI) represent the standard. In many cases it is possible to differentiate tumor recurrence from inflammation with the help of contrast-enhanced multiplanar MRI and to detect bone marrow changes prior to CT.     

Ossäre Manifestationen beim Non-Hodgkin-Lymphom im Kindes- und Jugendalter

PURPOSE: Skeletal manifestation of Non-Hodgkin's lymphoma is rare in pediatric patients. Objective of the study was to determine imaging features, before and after treatment, and to correlate these features with clinical outcome. METHODS: A retrospective analysis of 1246 patients from two therapy studies (NHL-BMF-90 and 95) was performed. Imaging studies of 63 patients with bone involvement of lymphoma were reevaluated. RESULTS: Incidence of initial bone involvement in Non-Hodgkin's lymphoma was 6.8%. Distribution was best assessed by bone scan, MRI revealed larger areas of marrow involvement and detected additional lesions. Sites of predilection were long bones of the lower extremities with epiphyseal involvement in 39%. Residual signal alterations in MRI after successful therapy remained in 71%. Osteonecrosis after therapy was a common finding. Clinical outcome war not correlated to the presence of bone involvement. CONCLUSIONS: Since clinical outcome is not effected by bone involvement in childhood NHL, value of screening may be limited. Knowledge of imaging characteristics is mandatory for initial evaluation of primary osseous lymphomas and symptomatic lesions as well as for therapy controls.     

Distinguishing stress fractures from pathologic fractures: a multimodality approach

Whereas stress fractures occur in normal or metabolically weakened bones, pathologic fractures occur at the site of a bone tumor. Unfortunately, stress fractures may share imaging features with pathologic fractures on plain radiography, and therefore other modalities are commonly utilized to distinguish these entities. Additional cross-sectional imaging with CT or MRI as well as scintigraphy and PET scanning is often performed for further evaluation. For the detailed assessment of a fracture site, CT offers a high-resolution view of the bone cortex and periosteum which aids the diagnosis of a pathologic fracture. The character of underlying bone marrow patterns of destruction can also be ascertained along with evidence of a soft tissue mass. MRI, however, is a more sensitive technique for the detection of underlying bone marrow lesions at a fracture site. In addition, the surrounding soft tissues, including possible involvement of adjacent muscle, can be well evaluated with MRI. While bone scintigraphy and FDG-PET are not specific, they offer a whole-body screen for metastases in the case of a suspected malignant pathologic fracture. In this review, we present select examples of fractures that underscore imaging features that help distinguish stress fractures from pathologic fractures, since accurate differentiation of these entities is paramount.     

MR imaging of ulnar impaction

The ulnar impaction syndrome of the wrist is a well-recognized clinical entity, usually showing distinct radiographic features including a positive ulnar variance and degenerative subchondral changes of the distal ulna, proximal lunate, and proximal triquetrum. Confirmation of the clinical and plain film findings with advanced imaging is often necessary to exclude other entities with a similar clinical presentation. Although arthrography and bone scintigraphy are helpful in this work-up, magnetic resonance imaging (MRI) appears to be both a sensitive and a specific means of evaluation. The imaging studies in four patients with clinically and surgically diagnosed ulnar impaction are described, with emphasis on MRI findings. MRI appears to be the modality of choice in the evaluation of patients with suspected ulnolunate impingement.     

Magnetic resonance imaging of spinal cord trauma: a pictorial essay

Assessing a patient with clinical signs of acute spinal cord trauma is an emergency. A radiological work-up is crucial in determining management, and magnetic resonance imaging (MRI) is the modality of choice. It should therefore be performed immediately, preferably within 3 hours, even when plain radiography does not show an abnormality. By choosing an appropriate imaging protocol, it is possible to assess the spinal cord, joints, muscles, ligaments and bone marrow of the spine. Moreover, early MRI findings assist in determining functional prognosis. A major limitation to early MRI is that the examination is usually restricted to stable trauma patients because of the difficulties in monitoring ventilated patients during scanning. However, when an anaesthesiologist with experience in MRI and MR-compatible monitoring equipment is available, even these patients can be safely examined. MRI is also indicated for the evaluation of patients with late complications and sequelae following spinal cord trauma, since many of these chronic lesions are potentially treatable.