MRI of bone marrow oedema associated with focal bone lesions

Imaging of bone marrow pitfalls with emphasis on MRI

Normal marrow contains both hematopoietic/red and fatty/yellow marrow with a predictable pattern of conversion and skeletal distribution on MRI. Many variations in normal bone marrow signal and appearances are apparent and the reporting radiologist must differentiate these from other non-neoplastic, benign or neoplastic processes. The advent of chemical shift imaging has helped in characterising and differentiating more focal heterogeneous areas of red marrow from marrow infiltration. This review aims to cover the MRI appearances of normal marrow, its evolution with age, marrow reconversion, variations of normal marrow signal, causes of oedema-like marrow signal, and some common non-neoplastic entities, which may mimic marrow neoplasms.

Clinical and magnetic resonance imaging feature differences between solitary and multiple type Langerhans cell histiocytosis involving the craniofacial bone

PURPOSE

To investigate the clinical and contrast-enhanced magnetic resonance imaging (MRI) features of craniofacial bone Langerhans cell histiocytosis (LCH) and discuss the differences between a solitary lesion group (SLG) and multiple lesions group (MLG).

METHOD

This study included 22 consecutive patients with pathologically proven LCH who underwent contrast-enhanced MRI. The clinical data and MRI features were retrospectively assessed.

RESULTS

The mean patient age was 5 years, and 15 patients were male. The frontal bone was the most frequently affected bone. Ten and 12 patients were classified into the SLG and the MLG, respectively. The following MRI features were observed in >50% cases: T1WI hyperintensity in 15 (68%) cases, T2WI hyperintensity in 16 (73%) cases, bulging sign in 18 (82%) cases, concentric or eccentric soft tissue mass formation in 13 (59%) cases, soft tissue edema in 16 (73%) cases, any grade of bone marrow edema in 16 (73%) cases, surrounding bone enhancement in 17 (77%) cases, and surrounding soft tissue enhancement in 16 (73%) cases. Patient age was significantly higher in the SLG than that in the MLG (P = 0.0014). Perilesional bone marrow edema and enhancement were significantly more prominent in the SLG than in the MLG (P = 0.032, P = 0.040).

CONCLUSIONS

Contrast-enhanced MRI showed additional significant findings of mainly the surrounding details. Older age, extensive bone marrow edema, and enhancement may indicate solitary-type LCH rather than multiple-type LCH. These differences may help distinguish between solitary- and multiple-type LCH, which have different treatment strategies.

Role of in-phase and out-of-phase chemical shift MRI in differentiation of non-neoplastic versus neoplastic benign and malignant marrow lesions

OBJECTIVE

To determine its ability of in-phase (IP) and out-of-phase (OOP) chemical shift imaging (CSI) to distinguish non-neoplastic marrow lesions, benign bone tumours and malignant bone tumours.

METHODS

CSI was introduced into our musculoskeletal tumour protocol in May 2018 to aid in characterisation of suspected bone tumours. The % signal intensity (SI) drop between IP and OOP sequences was calculated and compared to the final lesion diagnosis, which was classified as non-neoplastic (NN), benign neoplastic (BN) or malignant neoplastic (MN).

RESULTS

The study included 174 patients (84 males; 90 females: mean age 44.2 years, range 2-87 years). Based on either imaging features (n = 105) or histology (n = 69), 44 lesions (25.3%) were classified as NN, 66 (37.9%) as BN and 64 (36.8%) as MN. Mean % SI drop on OOP for NN lesions was 36.6%, for BN 3.19% and for MN 3.24% (p < 0.001). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of CSI for differentiating NN from neoplastic lesions were 65.9%, 94.6%, 80.6%, 89.1%% and 87.4% respectively, and for differentiating BN from MN were 9.1%, 98.4%, 85.7%, 51.2 and 53.1% respectively.

CONCLUSION

CSI is accurate for differentiating non-neoplastic and neoplastic marrow lesions, but is of no value in differentiating malignant bone tumours from non-fat containing benign bone tumours.

ADVANCES IN KNOWLEDGE

CSI is of value for differentiating non-neoplastic marrow lesions from neoplastic lesions, but not for differentiating benign bone tumours from malignant bone tumours as has been previously reported.

Langerhans cell histiocytosis of the shoulder girdle, pelvis and extremities: a review of radiographic and MRI features in 85 cases

OBJECTIVES

To describe the radiographic and MRI features of histologically proven Langerhans cell histiocytosis (LCH) of the bone.

MATERIALS AND METHODS

A retrospective review of the radiographic and MRI features of 85 histologically proven cases of skeletal LCH over a 12-year period. Clinical data recorded included age, gender and location. Radiographic features evaluated included Lodwick grading, cortical/periosteal response and matrix mineralisation. MRI features assessed included lesion size and T1-weighted signal intensity (T1W SI), nature of margin, hypointense rim, enhancement pattern, bone marrow and soft tissue oedema, soft tissue mass, fluid-fluid levels, the penumbra sign and the budding and bulging signs.

RESULTS

The study included 85 patients, 54 males and 31 females with mean age of 13 years (range 1-76 years). The femur was the commonest bone involved (38.8%), followed by the scapula (9.4%), clavicle (8.2%), ilium (8.2%) and ischium (8.2%). The mean maximal lesion size was 40 mm (range 16-85 mm). The commonest radiographic appearance was of a lytic lesion with no appreciable sclerotic rim, an intact expanded cortex and either absent or laminated periosteal response. MRI demonstrated a hypointense rim (41.5%), the budding (31.7%) and bulging (36.6%) signs, eccentric extra-osseous mass (42.7%), prominent bone marrow (95.3%) and soft tissue oedema (84.1%). Rarer features included haemorrhage (2.4%), the penumbra sign (3.5%) and fluid-fluid levels (2.4%). Thirteen of 25 post-contrast studies showed peripheral/rim enhancement with central necrosis.

CONCLUSIONS

LCH classically presents as a moderately aggressive lytic bone lesion on radiography, with prominent reactive bone and soft tissue oedema being a characteristic feature on MRI.

Anomalous signal intensity increase on out-of-phase chemical shift imaging: a manifestation of marrow mineralisation?

OBJECTIVE

In-phase (IP) and out-of-phase (OOP) chemical shift imaging (CSI) is an established technique for clarifying the nature of indeterminate bone marrow lesions, a signal intensity (SI) drop of > 20% at 1.5 tesla (T) or > 25% on 3 T on the OOP sequence being consistent with a non-neoplastic process. Occasionally, SI increase is seen on OOP sequences. The aim of this study is to determine if this is related to marrow sclerosis or matrix mineralisation.

MATERIALS AND METHODS

In 184 cases, the SI change on OOP was calculated. For patients in whom the SI on OOP increased compared with the IP sequence, available CT studies and radiographs were reviewed to look for marrow sclerosis and/or matrix mineralisation.

RESULTS

Forty out of 184 patients (34.25%) showed an anomalous increase in SI on the OOP sequence. CT studies were available in 27 cases (67.5%), of which medullary sclerosis was seen in 20 (74.1%) while matrix mineralisation was seen in a further 2 cases. Review of radiographs demonstrated matrix mineralisation in 6 cases, while punctate signal void consistent with chondral calcification was seen on MRI in 2 more cases. Based on either typical imaging features (n = 22) or histology (n = 18), 7 lesions (17.5%) were classed as non-neoplastic, 18 (45%) as benign neoplasms and 15 (37.5%) as malignant neoplasms.

CONCLUSION

When assessing focal marrow lesions with CSI, anomalous SI increase may be seen on the OOP sequence in approximately one-third of cases. In over 75% of such cases, CT or radiographs demonstrate either diffuse marrow sclerosis or matrix mineralisation.

MRI and clinical features of Langerhans cell histiocytosis (LCH) in the pelvis and extremities: can LCH really look like anything?

OBJECTIVE

To assess clinical and MRI features of Langerhans cell histiocytosis in the pelvis and extremities.

MATERIALS AND METHODS

The MRI and clinical features of 21 pathologically proven cases of LCH involving the pelvis and extremities were studied. Multiple characteristics of the lesions were evaluated (location, size, T1/ T2/post-contrast features, perilesional bone and soft tissue signal, endosteal scalloping, periosteal reaction, soft tissue mass, pathologic fracture). Pre-biopsy radiologic diagnoses were collected from the original clinical reports. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), temperature, and white blood cell count (WBC) were collected at the time of diagnosis when available.

RESULTS

The locations of the LCH lesions included five humerus, four femur, five ilium, one tibia, one clavicle, and three scapula. Lesional size ranged from 1.8 to 7.1 cm, with a mean of 3.6 cm. All lesions demonstrated perilesional bone marrow edema, periosteal reaction, endosteal scalloping, and post-contrast enhancement. An associated soft tissue mass was present in 15/21 (71.4 %). Clinically, the WBC, ESR, and CRP were elevated in 2/14 (14 %), 8/12 (67 %), and 4/10 (40 %) of cases, respectively. Fever was documented in 1/15 (7 %) patients and pain was reported in 15/15 (100 %).

CONCLUSIONS

The clinical and radiologic features of LCH in the pelvis and extremities overlap with infection and malignancy, but LCH must be considered in the differential diagnosis, as it routinely presents with aggressive MRI features, including endosteal scalloping, periosteal reaction, perilesional edema, and a soft tissue mass. Furthermore, an unknown skeletal lesion at presentation without aggressive MRI features is unlikely to represent LCH.

Evaluation of transient osteoporosis of the hip in magnetic resonance imaging

Transient osteoporosis is a relatively rare condition of unknown etiology that causes temporary bone loss. The syndrome is characterized by self-limited course and spontaneous resolution after 6 to 12 months. The pathogenesis of transient osteoporosis is not fully understood but several hypotheses that have been proposed include trauma, neurovascular dysfunction and transient hyperemia. Clinical manifestations include sudden onset of pain in the hip that usually worsens with weight bearing and leads to functional disability involving the affected extremity. Radiographs are frequently unremarkable, but may reveal periarticular osteopenia 3-6 weeks after the onset of clinical symptoms. There is no radiographic evidence of demineralization during the early phase of syndrome, as a result advanced imaging is required. Magnetic resonance imaging is the most sensitive and predictable test for an early diagnosis and monitoring of disease progression.

The role of MRI in image-guided needle biopsy of focal bone and soft tissue neoplasms

Magnetic resonance imaging (MRI) plays a critical role in the management pathway of both soft tissue and bone neoplasms, from diagnosis through to post-treatment follow-up. There are a wide range of surgical, oncological, and combined treatment regimes but these rely on accurate histopathological diagnosis. This article reviews the role of MRI in the planning of image-guided needle biopsy for suspected soft tissue and bone tumors.

Evaluation of pediatric bone lesions

The radiologist is commonly confronted with bone lesions in children. Knowledge of the age of the patient, the lesion location, and various imaging characteristics are all important in making an accurate diagnosis, and determining benign from malignant etiologies should be a primary goal. Various imaging features seen on cross-sectional imaging, including marrow edema, periosteal reaction patterns, and fluid-fluid levels, are discussed. The advantages of different imaging modalities, including CT and MRI, are reviewed.

Founder's lecture of the ISS 2006: borderlands of normal and early pathological findings in MRI of the foot and ankle

The purpose of this article is to highlight the anatomical variants, technical pitfalls, and the prevalence of abnormal conditions in the asymptomatic population in magnetic resonance imaging of the foot and ankle. Special attention is drawn to the complex anatomy of the deltoid ligament (the superficial tibionavicular ligament, tibiospring ligament, the tibiocalcaneal ligament, and the deep anterior and posterior tibiotalar ligaments) and the posterior tibial tendon insertion including the magic angle artifact and the high prevalence of asymptomatic findings such as "hypertrophied" peroneal tubercle (abnormal only when larger than 5 mm), peroneus quartus (prevalence 17%), and cysts (vascular remnants) just inferior to the angle of Gissane.

Bone marrow oedema associated with benign and malignant bone tumours

Bone marrow oedema is associated with a wide variety of pathological processes including both benign and malignant bone tumours. This imaging finding in relation to intraosseous tumours can aid in providing a more focused differential diagnosis. In this review, we will discuss the MR imaging of bone marrow oedema surrounding intraosseous neoplasms. The different pulse sequences used in differentiating underlying tumour from surrounding oedema are discussed along with the role of dynamic contrast enhanced MRI. Benign lesions commonly associated with bone marrow oedema include osteoid osteoma, osteoblastoma, chondroblastoma and Langerhan's cell histiocytosis. Metastases and malignant primary bone tumours such as osteosarcoma, Ewing's sarcoma and chondrosarcoma may also be surrounded by bone marrow oedema. The imaging findings of these conditions are reviewed and illustrated. Finally, the importance of bone marrow oedema in assessment of post chemotherapeutic response is addressed.

Bone marrow changes on STIR MR images of asymptomatic feet and ankles

The purpose of this study was to evaluate the prevalence, pattern and size of bone marrow changes on short-tau inversion recovery (STIR) magnetic resonance (MR) images of asymptomatic feet and ankles. In 78 asymptomatic volunteers (41 women, 37 men; median age 47 years; range 23-83 years) sagittal STIR MR images of hindfoot and midfoot were reviewed for various patterns of high signal changes in bone marrow. The size of these bone marrow changes was measured, and signal intensity was rated semi-quantitatively using a scale from 0 (=normal) to 10 (=fluid-like). Fifty percent (39/78) of all volunteers had at least one bone marrow change. Thirty-six percent (28/78) of all volunteers had edema-like changes, 26% (20/78) had necrosis-like changes, and 5% (4/78) had cyst-like changes. The long diameters of all changes varied between 4 mm and 16 mm (median 7.5 mm). The median signal intensity for all changes was 5.0 (range 1-10). Bone marrow changes on STIR MR images are commonly detected in asymptomatic feet and ankles. However, such changes tend to be small (<1 cm) or subtle.

The role of MR imaging in the diagnostic characterisation of appendicular bone tumours and tumour-like conditions

MRI has an established role in the local staging of primary bone tumours. However, as the majority of tumours have non-specific appearances on MRI, the diagnosis is usually established on the basis of clinical history, plain film findings and biopsy. This article reviews the value of MRI in the further characterisation of appendicular bone tumours and tumour-like lesions, with particular reference to peri-lesional oedema, fluid-fluid levels, flow voids, fat signal, cartilage signal and dedifferentiation. These features are a useful adjunct for distinguishing between benign and malignant disease, pointing towards a more specific diagnosis, and guiding biopsy.