MR imaging of edema accompanying benign and malignant bone tumors

[Bone marrow edema syndromes of the knee]

Bone marrow edema represents a common finding on magnetic resonance imaging (MRI) of the knee and other joints, which can occur as a primary pathology or as a secondary phenomenon of various bone and joint pathologies. This article reviews the terminology, definition, pathology and differential diagnosis of bone marrow edema of the knee taking into consideration current concepts.

ACR Appropriateness Criteria® Management of Vertebral Compression Fractures: 2022 Update

Vertebral compression fractures (VCFs) can have a variety of etiologies, including trauma, osteoporosis, or neoplastic infiltration. Osteoporosis related fractures are the most common cause of VCFs and have a high prevalence among all postmenopausal women with increasing incidence in similarly aged men. Trauma is the most common etiology in those >50 years of age. However, many cancers, such as breast, prostate, thyroid, and lung, have a propensity to metastasize to bone, which can lead to malignant VCFs. Indeed, the spine is third most common site of metastases after lung and liver. In addition, primary tumors of bone and lymphoproliferative diseases such as lymphoma and multiple myeloma can be the cause of malignant VCFs. Although patient clinical history could help raising suspicion for a particular disorder, the characterization of VCFs is usually referred to diagnostic imaging. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Multimodal Imaging Evaluation and Clinical Progress of Spinal Osteoblastoma: A Comprehensive Review

Spinal osteoblastoma is rare clinically, with insidious onset, atypical symptoms, and various imaging manifestations, which can easily lead to misdiagnosis and delayed diagnosis. It can cause severe neurological dysfunction in patients with intermediate to advanced stages and may easily recur after surgery. Imaging examinations such as radiography, computed tomography, magnetic resonance imaging, and positron emission tomography have different value for the diagnosis of spinal osteoblastoma, but they lack specificity. The preferred treatment is surgical resection, which is technically difficult, and in some cases, osteoblastoma cannot be completely removed. New clinical approaches such as radiofrequency ablation, radiotherapy, targeted chemotherapy, and other comprehensive treatments have emerged and are progressing rapidly, but no unified norms have yet been developed. This manuscript provides a systematic review of the literature and provides an extensive and comprehensive review of this rare tumor in terms of multimodality imaging manifestations and clinical progress.

Magnetic resonance imaging in differentiating between aggressive and non-aggressive bone tumors

BACKGROUND

While radiography remains essential in the initial evaluation of bone lesions, tissue biopsy or further imaging is often required to clarify indeterminate radiographic features. Magnetic resonance imaging (MRI) assists radiologists in evaluating lesions with indeterminate features as it has advantages in delineating tumorous tissues and bone marrow.

PURPOSE

To evaluate the association factors of MRI for bony aggressiveness.

MATERIAL AND METHODS

A retrospective analysis of 226 MRI examinations from patients diagnosed with bone tumors in a tertiary hospital during 2008-2018 was performed. All the MR images were interpreted by musculoskeletal radiologists without diagnostic information. The bony lesions were categorized into aggressive and non-aggressive groups using tumor margin, cortical changes, periosteal reaction, joint extension, extraosseous soft tissue involvement, tumor homogeneity, and enhancement pattern from the MR images. Univariable and multivariable analysis were applied for each feature on the MRI scans. In addition, sensitivity and specificity were calculated for MRI diagnoses of aggressive bone lesions.

RESULTS

In total, 180 aggressive and 46 non-aggressive bone lesions were examined on MRI. The sensitivity and specificity of MRI for differentiating between aggressive and non-aggressive bone lesions were 98.89% and 50%, respectively. Ill-defined margin, cortical break, cortical signal changes, sunburst and Codman's triangle periosteal reaction, joint extension, and tumoral and heterogeneous enhancement could be predictive signs for aggressive bone lesions.

CONCLUSION

MRI can be a valuable tool to assist in distinguishing aggressive from non-aggressive bone lesions. In cases of indeterminate radiographic features, MRI could be used as an additional imaging to improve diagnostic accuracy and could reduce unnecessary invasive procedures.

Atraumatic Bone Marrow Edema Involving the Epiphyses

Bone marrow edema (BME)-like signal intensity involving the epiphyses of tubular bones represents a frequent magnetic resonance imaging finding associated with a wide spectrum of bone and joint disorders. It is important to distinguish this finding from cellular infiltration of bone marrow and to be aware of the differential diagnosis of underlying causes. With a general focus on the adult musculoskeletal system, this article reviews the pathophysiology, clinical presentation, histopathology, and imaging findings of nontraumatic conditions associated with epiphyseal BME-like signal intensity: transient bone marrow edema syndrome, subchondral insufficiency fracture, avascular necrosis, osteoarthritis, arthritis, and bone neoplasms.

[Conventional epiphyseal chondrosarcoma of childhood and adolescence: a case report]

INTRODUCTION

Conventional chondrosarcoma is the second most common primary malignant bone tumor and usually occurs at older adult ages. It is rare in childhood and adolescence.

CASE HISTORY

This case report presents the treatment course of a 13-year-old boy with a symptomatic chondrogenic tumor of the right distal femur. Histopathologically, an epiphyseal intermediate-grade chondrosarcoma (G2) was diagnosed.

DISCUSSION

Based on the following case, potential radiological and histopathological differential diagnoses, such as chondroblastoma or chondroblastic osteosarcoma, are discussed against the background of current standards in orthopedic oncology.

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.

Spinal osteoblastoma: a retrospective study of 35 patients' imaging findings with an emphasis on MRI

Objective

To investigate the values of multimodal imaging approaches in the diagnosis of spinal osteoblastomas with an emphasis on MRI findings.

Materials and methods

We retrospectively evaluated the imaging findings of 35 patients with spinal osteoblastomas. The imaging methods included radiography, whole-body bone scintigraphy (WBBS), CT and MRI.

Results

Radiography detected 87.1% (27/31) of the lesions; WBBS demonstrated increased radionuclide activity in all the lesions. CT could precisely show and localize all niduses, and calcification was always detected. MRI usually could adequately delineate the niduses of osteoblastomas, especially on T2WI (88.2%; 30/34). 71.9% (23/32) of osteoblastomas were surrounded with moderate or extensive bone marrow edema (BME) with soft tissue edema (STE). STE always extended along the muscle bundle adjacent to the lesion; there was no subcutaneous fat involvement. BME was eccentrically distributed in the vertebral body and spread inward from the sides of the nidus. The extent of BME in the vertebral body tended to be inversely proportional to the distance from the nidus. In addition, rare magnifications of osteoblastoma including multifocal diseases (n = 2), vertebra plana (n = 1) or with aneurysmal bone cysts (n = 6) were also observed in our study.

Conclusions

In patients showing moderate or extensive BME together with STE on MRI, both CT and MRI should be used to confirm nidus presence. The above-mentioned characteristics of edema on MRI of patients with spinal osteoblastoma are helpful in not only localizing the nidus, but also enhancing the diagnostic confidence.

Imaging algorithm and multimodality evaluation of spinal osteoblastoma

Background

To analyze the features of CT, MRI and PET/CT and their diagnostic value for spinal osteoblastomas (OBs).

Methods

The radiological and clinical data of 21 patients with histopathologically-confirmed spinal OBs were analyzed retrospectively.

Results

Sixteen of the 21 cases were benign and 5 were aggressive OBs. Tumors were located in the lumbar (n = 11), cervical (n = 4), thoracic (n = 5), and sacral (n = 1) spinal regions. Nineteen cases were centered in the posterior elements of the spine, 13 of which extended into the vertebral body. Punctate or nodular calcifications were found in all cases on CT with a complete sclerotic rim (n = 12) or incomplete sclerotic rim (n = 8). The flare phenomenon (indicative of surrounding tissue inflammation) was found in 17/21 cases on CT, thin in 11 cases and thick in 6 cases, and in 19/19 cases on MRI, thin in 1 case and thick in 18 cases. On ¹⁸F-FDG PET/CT, all cases (8/8) were metabolically active with the SUVmax of 12.3–16.0; the flare sign was observed in 8 cases, including 7 cases of hypometabolism and 1 case of coexistence of hypermetabolism and hypometabolism. Based on CT, 3, 12, and 6 cases were classified as Enneking stage 1, 2 and 3, respectively. Of 19 cases with MRI, 1 and 18 cases were classified as Enneking stage 2 and 3, respectively.

Conclusions

Spinal OB has multiple unique characteristic radiological features. Although a larger sample size is needed, combining CT, MRI and PET may be beneficial to optimize preoperative diagnosis and care of patients with OBs.

Edema Surrounding Benign Tumors and Tumor-Like Lesions

Objective

To explore the incidence and significance of intra- and extra-osseous edema associated with benign tumors and tumor-like diseases.

Methods

Magnetic resonance imaging (MRI) data from 300 benign osseous tumors and tumor-like diseases diagnosed by pathology were retrospectively reviewed. Borderline tumors, cases associated with pathological fractures, and skull lesions were excluded from the study. Bone marrow and soft tissue edema were defined on T2WI with fat suppression on MRI in all cases. The incidence rate of edema in benign tumors and tumor-like diseases was determined using the χ ² test. The preoperative diagnoses were reviewed, and the effect of edema on the differential diagnosis of benign and malignant tumors was analyzed.

Results

The incidence rate of bone marrow and soft tissue edema associated with benign tumors and tumor-like diseases was 35.7% (107/300), including 84.4% (27/32) Langerhans cell histiocytosis, 86.4% (19/22) osteoblastoma, 93.9% (31/33) osteoid osteoma, and 85.2% (23/27) chondroblastoma cases. There was no statistically significant difference in the incidence of edema among the four diseases (χ ² = 1.7, P > 0.05). Of 107 cases associated with edema, 49 (45.8%) were misdiagnosed as malignant tumors by MRI preoperatively.

Conclusion

Bone marrow and soft tissue edema are a common finding associated with benign bone tumors and tumor-like diseases, and they are frequently detected in Langerhans cell histiocytosis, osteoblastoma, osteoid osteoma, and chondroblastoma.

Systematic review on the utility of magnetic resonance imaging for operative management and follow-up for primary sarcoma-lessons from extremity sarcomas

Primary sarcomas of the vertebral column affect roughly 5 in every million persons annually, of which half to one-third are malignant. Treatment of these lesions requires multimodal management, often employing attempts at en bloc resection of the lesion with negative margins. This may be facilitated using magnetic resonance imaging for preoperative margin planning, but current literature is lacking regarding the use of such imaging to accurately predict planned surgical margins. Here we review prior studies describing the use of magnetic resonance imaging for en bloc resection of sarcomas of the extremities to identify learning points for application to the treatment of spinal neoplasms. We conducted a systematic review of the PubMed and EMBASE literature. Included studies described the accuracy of MRI for preoperative evaluation of tumor margins, intraoperative guidance for en bloc resection, or post-operative evaluation of residual or recurrent disease. All included studies described patients treated for osseous or soft tissue sarcoma of the limbs. We found 1,705 unique references of which 27 met criteria for inclusion. Seven studies reported MR had an overall diagnostic accuracy of 93.6-96% for preoperative margin evaluation with non-contrast T1 most accurately reflecting true margins. In the nine articles reporting results of MR-guided resection, negative margins were achieved in 88.8-100% of cases with a closest margin of 2-4 mm. Eleven articles combined reported the accuracy of MR for residual disease or local recurrence, with a mean sensitivity and specificity of 71.7% and 79.3%, respectively for residual disease and 87.9% and 85.9%, respectively for local recurrence. The current literature for appendicular musculoskeletal sarcoma suggests that MR is highly accurate for defining tumor margins preoperatively, guiding osteotomy cuts intraoperatively, and documenting recurrence or residual disease. Further evidence is necessary to evaluate the degree to which it can accurately guide osteotomy planning for en bloc resection of vertebral primaries.

ACR Appropriateness Criteria® Management of Vertebral Compression Fractures

Vertebral compression fractures (VCFs) have various causes, including osteoporosis, neoplasms, and acute trauma. As painful VCFs may contribute to general physical deconditioning, management of painful VCFs has the potential for improving quality of life and preventing superimposed medical complications. Various imaging modalities can be used to evaluate a VCF to help determine the etiology and guide intervention. The first-line treatment of painful VCFs has been nonoperative or conservative management as most VCFs show gradual improvement in pain over 2 to 12 weeks, with variable return of function. There is evidence that vertebral augmentation (VA) is associated with better pain relief and improved functional outcomes compared to conservative therapy for osteoporotic VCFs. A multidisciplinary approach is necessary for the management of painful pathologic VCFs, with management strategies including medications to affect bone turnover, radiation therapy, and interventions such as VA and percutaneous thermal ablation to alleviate symptoms. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Soft tissue sarcoma: adding diffusion-weighted imaging improves MR imaging evaluation of tumor margin infiltration

PURPOSE

To determine the added value of diffusion-weighted imaging (DWI) to conventional magnetic resonance (MR) imaging in assessment of tumor margin infiltration in soft tissue sarcoma (STS) at 3T.

MATERIALS AND METHODS

The institutional review board approved this retrospective study. Forty-five patients who underwent 3T MR imaging including DWI and were pathologically confirmed were included in this study. Two readers retrospectively scored conventional MR imaging alone. Then, they assessed a combination of conventional MR imaging and DWI. At pathology, margin infiltration was retrospectively reviewed by one pathologist blinded to MR findings. Areas under the curve (AUCs) of the receiver-operating characteristic curve were obtained for diagnostic performance. Interobserver agreement for the scoring of margin infiltration of STS was assessed with kappa statistics.

RESULTS

Among 45 cases of STS, 33 had infiltrative tumor margin at pathology. Sensitivity, specificity, and accuracy of each reader were 100%, 17%, and 78%; 97%, 25%, and 78% on conventional MR imaging alone and 94%, 67%, and 87%; 94%, 42%, and 80% on conventional MR imaging combined with DWI. AUCs of conventional MR imaging combined with DWI were significantly higher than those of conventional MR imaging alone: 0.890 vs 0.678 (p = .0123) and 0.846 vs 0.640 (p = .0305) for each reader. Interobserver agreements of conventional MR imaging alone and conventional MR imaging combined with DWI were moderate to substantial (κ = 0.646, κ = 0.496).

CONCLUSION

The addition of DWI to conventional MR imaging may improve specificity for assessing tumor margin infiltration in STS at 3T.

KEY POINTS

• DWI has added value for assessment of tumor margin infiltration in soft tissue sarcoma. • Addition of DWI to conventional MRI at 3T may improve specificity. • Addition of DWI to conventional MRI may help orthopedic surgeon determine the extent of the resection margin.

Unusual presentation of osteoblastoma as vertebra plana-a case report and review of literature

BACKGROUND

Osteoblastoma is rare and accounts for 3% of all benign tumors and 1% of all bone tumors. The spine is the most common site of occurrence, constituting 32% to 45% of all osteoblastomas. It has a strong predilection for the posterior elements, most often occurring in the lumbar spine.

METHOD

In this case report, we describe an unusual presentation of spinal osteoblastoma presenting as thoracic T9 vertebra plana in a 20-year-old female. She presented with discomfort over the midback with unsteadiness of gait. The patient underwent detailed investigations including computed tomography (CT), magnetic resonance imaging, and CT-guided biopsy. To our knowledge, this is the first case report of vertebra plana due to spinal osteoblastoma in the English literature.

RESULT

The patient successfully underwent posterior decompression of T9 with laminectomy followed by minimally invasive surgery posterior instrumentation from T7 to T11. Histopathology of the intraoperative specimen was consistent with osteoblastoma. The patient had an uneventful postoperative recovery and no evidence of tumor recurrence could be demonstrated on positron emission tomography scan at 15 months' follow-up.

CONCLUSION

In conclusion, the differential diagnosis for vertebra plana is extensive and we add spinal osteoblastoma as another etiology to the existing list. Diagnosis and treatment of vertebra plana involve multimodality radiological imaging, and careful histological and surgical evaluation to identify the underlying etiology.

Synergistic role of simultaneous PET/MRI-MRS in soft tissue sarcoma metabolism imaging

The primary objective of this study was to develop and validate simultaneous PET/MRI-MRS as a novel biological image-guided approach to neoadjuvant radiotherapy (RT) and/or chemoradiation (chemoRT) in soft tissue sarcomas (STS). A patient with sarcoma of the right thigh underwent PET/MRI scan before and after neoadjuvant (preoperative) radiotherapy. The magnetic resonance imaging (MRI) and 2-deoxy-2-[fluorine-18]-fluoro-D-glucose-Positron Emission Tomography ((18)F-FDG-PET) scans were performed simultaneously. In the post-radiation scan, magnetic resonance spectroscopy (MRS) was subsequently acquired with volume of interest positioned in a residual hyper-metabolic region detected by PET. Post-radiation PET/MRI showed a residual T2-hyperintense mass with significantly reduced (18)F-FDG-uptake, compatible with near complete response to radiotherapy. However, a small region of residual high (18)F-FDG uptake was detected at the tumor margin. MRS of this region had similar metabolite profile as normal tissue, and was thus considered false positive on PET scan. Pathology results were obtained after surgery for confirmation of imaging findings.

Extraosseous thoracic foraminal osteoblastoma: diagnostic dilemma and management with 3 year follow-up

Osteoblastomas are bone forming lesions arising mainly from posterior elements of the vertebra. They are commonly encountered in the cervical and lumbar regions. We present a case of a thoracic osteoblastoma which is extra osseous and is not communicating with any part of the vertebra present intraforaminally. This is a rare presentation of an osteoblastoma. Imaging studies do not accurately diagnose the osteiod lesion. The size of the lesion and cortical erosion seen on the computed tomography scan help in differentiating the osteoid osteoma and osteoblastoma, but they are less sensitive and specific. Thus a histopathology is the investigation of choice to diagnose the osteoblastoma. Early and adequate removal of mass prevents malignant transformation, metastasis, and recurrence. In our case we excised the pars interarticularis unilaterally, removed the osteoid mass intact, and performed unilateral instrumented fusion. There was no recurrence and solid fusion was seen at 3 years follow up.

Elevated preoperative systemic inflammatory markers predict poor outcome in localized soft tissue sarcoma

BACKGROUND

Systemic inflammation has been implicated in cancer development and progression. This study sought to determine whether systemic inflammatory markers can predict postoperative outcome in soft tissue sarcoma (STS).

METHODS

A total of 162 cases of primary, localized STS were reviewed. Patients with evidence of infectious or inflammatory diseases were excluded. The mean follow-up period was 46.7 months. The level of serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and neutrophil-to-lymphocyte ratio (NLR) measured before surgery were evaluated for association with disease-specific survival and local recurrence.

RESULTS

The mean values of CRP, ESR, and NLR were 0.79 mg/dL, 18.8 mm/h, and 2.12, respectively. Cutoff values derived from receiver-operating characteristic curve analysis were 0.20 mg/dL for CRP, 10.0 mm/h for ESR, and 2.50 for NLR. On univariate analysis, all inflammatory markers were associated with disease-specific survival (CRP: P = 0.007; ESR: P = 0.022; NLR: P = 0.030). On multivariate analysis, the CRP level (P = 0.019) and ESR (P = 0.013) remained significant. Elevation of multiple markers was a more significant prognostic factor than elevation of a single marker (P = 0.001). However, none of the inflammatory markers was associated with local recurrence (CRP: P = 0.345; ESR: P = 0.271; NLR: P = 0.570). Histologic grade was strongly correlated with inflammatory marker values (NLR: P < 0.001; ESR: P = 0.002; CRP: P = 0.007).

CONCLUSIONS

Preoperative systemic inflammatory status, assessed by using multiple serum markers, predicted disease-specific survival in STS.

Clinical characteristics and treatment options for two types of osteoblastoma in the mobile spine: a retrospective study of 32 cases and outcomes

PURPOSE

A retrospective study of 32 patients with osteoblastoma (OBL) in the mobile spine was performed to analyze the clinical characteristics of two types of spinal OBL. We also aimed to find influential factors for OBL in the mobile spine.

METHODS

Between 2002 and 2011, 32 patients with either conventional osteoblastoma (CO) or aggressive osteoblastoma (AO) in the mobile spine were treated in our center. All patients were treated with either total excision or subtotal excision + postoperative radiotherapy. The mean follow-up was 45.8 (18-128) months. Clinical data and surgery efficacy were analyzed to search for clinical characteristics of two subtypes of spinal OBL and discuss the possible factors influencing relapse.

RESULTS

There is significant difference between CO and AO in tumor size (p < 0.0005), preoperative alkaline phosphatase (ALP, p < 0.0005) and intraoperative blood loss (p = 0.013). Multivariate logistic regression was used to find the influential factors for relapse and the results were: preoperative ALP, b = 0.023, p = 0.029; surgery protocol, b = -7.597, p = 0.007; tumor size, ≥3/<3, b = 24.805, p < 0.0005; age, b = 0.054, p = 0.632; and pathology type, b = 1.998, p = 0.34.

CONCLUSIONS

Tumor size, preoperative ALP and CT images were helpful for distinguishing AO from CO. The difference in intraoperative blood loss between CO and AO is mainly attributed to the size of the lesion. Preoperative ALP, surgery protocol and tumor size (≥3/<3) were considered to significantly influence relapse of spinal OBL.

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.

Agreement among RTOG sarcoma radiation oncologists in contouring suspicious peritumoral edema for preoperative radiation therapy of soft tissue sarcoma of the extremity

PURPOSE

Peritumoral edema may harbor sarcoma cells. The extent of suspicious edema (SE) included in the treatment volume is subject to clinical judgment, balancing the risk of missing tumor cells with excess toxicity. Our goal was to determine variability in SE delineation by sarcoma radiation oncologists (RO).

METHODS AND MATERIALS

Twelve expert ROs were provided with T1 gadolinium and T2-weighted MR images of 10 patients with high-grade extremity soft-tissue sarcoma. Gross tumor volume, clinical target volume (CTV)3cm (3 cm longitudinal and 1.5 cm radial margin), and CTV2cm (2 cm longitudinal and 1 cm radial margin) were contoured by a single observer. Suspicious peritumoral edema, defined as abnormal signal on T2 images, was independently delineated by all 12 ROs. Contouring agreement was analyzed using the simultaneous truth and performance level estimation (STAPLE) algorithm and kappa statistics.

RESULTS

The mean volumes of GTV, CTV2cm, and CTV3cm were, respectively, 130 cm(3) (7-413 cm(3)), 280 cm(3) and 360 cm(3). The mean consensus volume computed using the STAPLE algorithm at 95% confidence interval was 188 cm(3) (24-565 cm(3)) with a substantial overall agreement corrected for chance (mean kappa = 0.71; range: 0.32-0.87). The minimum, maximum, and mean volume of SE (excluding the GTV) were 4, 182, and 58 cm(3) (representing a median of 29% of the GTV volume). The median volume of SE not included in the CTV2cm and in the CTV3cm was 5 and 0.3 cm(3), respectively. There were 3 large tumors with >30 cm(3) of SE not included in the CTV3cm volume.

CONCLUSION

Despite the fact that SE would empirically seem to be a more subjective volume, a substantial or near-perfect interobserver agreement was observed in SE delineation in most cases with high-grade soft-tissue sarcomas of the extremity. A median of 97% of the consensus SE is within the CTV2cm (99.8% within the CTV3cm). In a minority of cases, however, significant expansion of the CTVs is required to cover SE.

MR differentiation of low-grade chondrosarcoma from enchondroma

PURPOSE

To evaluate magnetic resonance (MR) imaging for the discrimination between low-grade chondrosarcoma and enchondroma.

MATERIALS AND METHODS

MR images of 34 patients who were confirmed with low-grade chondrosarcoma or enchondroma were retrospectively reviewed. After review of medical records, MR findings in 18 patients with low-grade chondrosarcoma and 16 patients with enchondroma were compared. MR images were retrospectively reviewed for the lesion location (central or eccentric; epiphysis, metaphysic, or diaphysis), margin, contour, mineralized matrix, endosteal scalloping, cortical expansion, cortical destruction, soft tissue mass formation, and periosteal reaction. Signal intensity, the patterns of contrast enhancement (unilocular or multilobular), soft tissue mass, and adjacent abnormal bone marrow and soft tissue signal were also reviewed. Statistical analysis was performed with chi-square test.

RESULTS

The patients with low-grade chondrosarcoma had a significantly higher incidence of MR findings (P<.05): predominantly intermediate signal on T1-weighted images [72% (13/18) in low-grade chondrosarcoma vs. 25% (4/16) in enchondroma], multilocular appearance on contrast-enhanced T1-weighted images [83% (15/18) vs. 44% (7/16)], cortical destruction [33% (6/18) vs. 0% (0/16)], a soft tissue mass [28% (5/18) vs. 0% (0/16)], adjacent bone marrow and soft tissue abnormal signal [22% (4/18) vs. 0% (0/16)], and an involvement of the epiphysis or flat bone [56% (10/18) vs. 19% (3/16)].

CONCLUSION

MR imaging shows helpful features for differentiating low-grade chondrosarcoma from enchondroma.

A clinicopathologic correlation in osteoblastoma of the spine in a child

Spinal osteoblastomas are considered benign tumors but can be locally aggressive. Patients usually present with pain and undergo radiologic and histologic work-up to establish a diagnosis. Osteoblastomas have discordant appearances on CT scans and MRI because of the inflammatory response seen on MRI that characterizes these tumors - the "flare" phenomenon. Solely using MRI can lead to over-resection, as signal abnormality may include areas devoid of tumor. There are a few reports of this phenomenon in the radiology literature, but to our knowledge, there are none in neurosurgery journals. We report an 11-year-old boy who presented with back pain and radiculopathy with an osteoblastoma at the L4 level. We totally excised the lesion to definitively treat the patient but also, based on MRI findings, differentially biopsied portions of the lesion and correlated them to the imaging studies, to confirm that the intense reactive portion of the lesion was devoid of tumor cells.

Pediatric cervical spine marrow T2 hyperintensity: a systematic analysis

OBJECTIVE

Hyperintense areas of vertebral bone marrow on fluid-sensitive sequences are at times seen on pediatric MRI of the cervical spine in children without suspicious clinical conditions to explain marrow pathology. Although these likely have no clinical significance they may be mistaken for pathology. The purpose of this study is to systematically evaluate the locations and patterns of marrow T2 hyperintensity in the pediatric cervical spine, with respect to age.

MATERIALS AND METHODS

At 1.5 T, the C2 through T3 vertebrae of 82 children aged 0-17 years without clinically suspicious marrow abnormality were retrospectively reviewed by two musculoskeletal radiologists, who were blinded to patients' age. The frequency, intensity, and location of the foci of marrow T2 hyperintensity were recorded for each vertebra on a 12-point scoring system and were correlated with the patients' age.

RESULTS

Foci of marrow hyperintensity were seen in 46/82 (56.1%) patients and in 241/734 (32.8%) vertebrae. Foci were most common in C4 (42% of patients), C5 (45.7%), and C6 (37.8%). The foci of T2 hyperintensity were more common inferiorly (188 foci) and adjacent to the anterior cortex (123). Analysis revealed no significant correlation between age and marrow score (Spearman = -0.147, P = 0.19), but did find a trend towards increased presence of marrow T2 hyperintensity in the ages of most rapid growth, 8-14 years (81.5% of patients).

CONCLUSION

Vertebral body marrow T2 hyperintensity was most common endosteally and in the mid-cervical spine with a slight peak in adolescence. We therefore believe that these pediatric cervical marrow changes may be related to rapid bone growth at the point of maximal kyphotic stress.

[MRI morphology of bone tumors and tumor-like lesions]

Spin-echo sequences are mandatory at MRI for staging and characterization of bone tumors and tumor-like lesions. MRI is of minor value in the estimation of the malignant potential of an osseous lesion. Although many bone tumors and tumor-like lesions present similar morphology at MRI, some entities can be diagnosed with good reliability. These include chondrogenic tumors, solitary and aneurysmal bone cysts, giant cell tumors, lesions containing fatty tissue and, to a certain extent, osteoid-osteomas and osteoblastomas. Practical advice is given regarding when to perform a MRI study in cases of tumor suspicion. Further advice is given for cases a tumor is found incidentally at a MRI study, how to modify the study and which kind of tumor may be present.

Age dependent T2 changes of bone marrow in pediatric wrist MRI

OBJECTIVE

Hyperintensity of the bone marrow on fluid-sensitive sequences can be seen on magnetic resonance imaging (MRI) during childhood, even in the absence of bone pathology. They can be related to hematopoietic marrow, normal and abnormal bone remodeling. We sought to investigate whether hyper intensity of the bone marrow on MRI of the wrist is age-dependent and to evaluate if this signal follows a consistent age-related pattern.

MATERIALS AND METHODS

Thirty-one wrist 1.5 T MR images of children (7-18 years) without suspected bone pathology were evaluated for foci of hyperintense bone marrow seen on fluid-sensitive coronal sequences using a scale of 1-3. Correlation of frequency, location and intensity of these foci with age was obtained. Results were analyzed for distribution in single bones and in the following regions: distal forearm, first/second carpal rows, and metacarpal bases.

RESULTS

A total of 448 bones were evaluated. Eighty-eight out of 448 (21 out of 31 wrists) showed hyperintense bone marrow seen on fluid-sensitive sequences. The distribution was: radius in 19, ulna in 19, first metacarpal base in 11, scaphoid in 9, lunate in 6, pisiform in 6, and fifth metacarpal base in 1. The involvement of the first and second carpal rows and the metacarpal bases was almost similar (13, 12, and 12 respectively). In the distal forearm, the intensity was similar to or higher than that in the wrist (2.2 vs. 2.0). Frequency decreased with age (100% at 7-9 and 25% at 16-18 years).

CONCLUSION

Foci of hyperintense bone marrow seen on fluid-sensitive sequences can be seen on MRI of the wrist during childhood even without apparent symptoms. It shows a consistent pattern with maturation: frequency and intensity decrease and there is distal-to-proximal resolution. This may be a normal finding that may represent normal bone remodeling or decreasing hematopoietic marrow and should not be confused with pathological bone marrow edema.

Osteoblastoma of the spine with discordant magnetic resonance imaging and computed tomography imaging features in a child

STUDY DESIGN

Case report.

OBJECTIVE

To describe the magnetic resonance imaging (MRI) and computed tomography (CT) findings of spinal osteoblastoma and illustrate how MRI features can be potentially misleading.

SUMMARY OF BACKGROUND DATA

Osteoblastoma is a rare benign tumor of bone that is known to incite a localized inflammatory response. These inflammatory features can simulate malignant behavior on MRI and can lead to misdiagnosis and unnecessarily aggressive resection unless one recognizes the classic benign features on CT. We present a case of osteoblastoma in a child to illustrate this concept.

METHODS

The patient's clinical and radiologic history is discussed with a brief review of the relevant literature.

RESULTS

A 9-year-old girl with back pain receives an MRI of the lumbar spine demonstrating a sacral tumor with potentially malignant features including extensive marrow edema and enhancement. A CT demonstrates a well-circumscribed lesion without lytic changes or malignant bone formation. A benign lesion was favored given the CT features and conservative resection was performed. Final pathologic diagnosis was osteoblastoma.

CONCLUSION

This case illustrates that the MRI findings for osteoblastoma can be misleading and caution should be used when evaluating benign tumors with known inflammatory responses on MRI. CT features seem to more accurately reflect the true nature and extent of the tumor.

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.

Assessment of Musculoskeletal Infection in Rats to Determine Usefulness of SPIO-Enhanced MRI

OBJECTIVE

The objective of our study was to evaluate the usefulness of superparamagnetic iron oxide (SPIO)-enhanced MRI in experimental models of infectious disease and to analyze the intracellular uptake of SPIO.

MATERIALS AND METHODS

Nine rats with infectious arthritis of the knee or soft-tissue infection were imaged on an MRI unit on days 4-6 after i.v. injection of a bacterial suspension. All animals were imaged on a T2-weighted fast spin-echo sequence before and 24 hours after administration of SPIO. The nine rats were classified into two groups according to the dose of SPIO. We calculated the relative signal-to-noise ratio (SNR) change and compared the relative SNR change with the histologic findings. We analyzed iron-loaded cells and the intracellular uptake of iron particles according to the dose of SPIO.

RESULTS

The SNR value decreased in proportion to the increase in the number of iron-laden macrophages or fibroblasts in the wall of the soft-tissue abscess (p < 0.01). The intracellular uptake of iron particles was shown in fibroblasts as well as in macrophages, and their uptake in the fibroblasts was greater than that in the macrophages (p < 0.05). There was no statistically significant difference in the intracellular uptake of iron particles according to the dose of SPIO (p > 0.1).

CONCLUSION

SPIO-enhanced MRI can be useful in evaluating infectious disease of the joint or soft tissue and is influenced by the uptake of iron particles in fibroblasts as well as macrophages.

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.

MRI of bone marrow oedema associated with focal bone lesions

AIM

To quantify the volume of bone marrow oedema surrounding focal bone lesions and to identify its relevance relative to diagnosis.

METHODS

Three hundred and eighty-eight of 1456 patients included in the orthopaedic oncology database who underwent magnetic resonance imaging (MRI) demonstrated bone marrow oedema and were included in the study. There were 225 males and 163 females, age range 1-87 years (mean 29 years). MRI images were retrospectively reviewed and assessed for the extent of bone marrow oedema. The amount of oedema was graded: grade 1: oedema present but smaller than the lesion size; grade 2: oedema equivalent to the lesion size; grade 3: oedema greater than the lesion size.

RESULTS

There were 190 grade 1 lesions: 56% malignant, 33% benign, 11% non-neoplastic; 74 grade 2 lesions: 19% malignant, 50% benign, 31% non-neoplastic; and 124 grade 3 lesions: 10% malignant, 46% benign, 44% non-neoplastic. There was a significant relationship between oedema grade (i.e., volume of oedema) and final diagnosis (p<0.0005).

CONCLUSION

Bone marrow oedema may be associated with a wide range of focal bony lesions, including malignant, benign and non-neoplastic causes. As the volume of bone marrow oedema increases relative to the size of the underlying lesion, the probability that the underlying lesion is benign is increased.

High-signal T2 changes of the bone marrow of the foot and ankle in children: red marrow or traumatic changes?

BACKGROUND

High-signal T2-weighted bone marrow changes can be found in both bone marrow edema and hematopoietic marrow and are often seen on pediatric MR images of the feet and ankle.

OBJECTIVE

To evaluate whether high-signal T2 changes of the bone marrow seen on pediatric MRI of feet and ankles represent residual hematopoietic marrow.

MATERIALS AND METHODS

A total of 402 bones in 41 pediatric MRI studies of feet and ankles (34 children, 1-18 years) were reviewed by two observers who were blinded to the patients' ages. The studies were reviewed for the presence of high-signal changes of the bone marrow on sagittal fluid-sensitive images. The frequency and location of these foci were correlated with the patients' ages.

RESULTS

High-signal T2 changes of the bone marrow were seen in 45/402 bones (11%) and in 24/41 patients younger than 16 years (59%). The changes were most commonly located in the calcaneus (54%), followed by the talus (35%) and navicular bone (35%), invariably at the endosteal surface. In 16 ankles, such foci were seen in the feet but not in the distal tibia/fibula. Symmetric presence (two ankles) or absence (four ankles) of high-signal marrow were seen in six of seven patients with bilateral ankles.

CONCLUSION

High-signal T2 changes of the bone marrow in pediatric feet and ankle MRIs have a symmetric, fairly consistent pattern and disappear after the age of 15 years. We believe that these high-signal areas are normal and represent residual hematopoietic marrow.

Occipitoparietal benign osteoblastoma: should entire lesion be resected when magnetic resonance images reveal wide abnormal signal intensity in surrounding bone marrow?

BACKGROUND

Benign osteoblastoma is an uncommon primary bone tumor that usually affects long bones and the vertebral column. Its occurrence in the calvarium is rare. Despite the characteristically benign nomenclature of osteoblastoma, it sometimes recurs with the possibility of transforming into a malignant form after an incomplete resection. Therefore, radical resection is recommended whenever possible. However, it has not been clarified whether the adjacent bones should also be completely resected when magnetic resonance (MR) images reveal abnormal signal intensity in the bone marrow.

CASE DESCRIPTION

Presented in this case report is a 12-year-old boy with occipital tenderness associated with occipitoparietal bone tumor. Neuroradiological studies demonstrated a solid tumor located in the occipital bone extending over the right parietal bone. Magnetic resonance images further revealed abnormal signal intensity in the bone marrow of the entire occipital and bilateral parietal bones. Macroscopically, the calvarial bone adjacent to the solid tumor appeared to be reddish, but it was not covering the entire area, contradicting the abnormal intensity found on the preoperative MR images. The resected area was determined according to macroscopic findings, and bones with normal color tone were preserved. Because histological examination did not clearly indicate tumor invasion at the margin of the resection site, no additional therapy was given. Although MR images revealed abnormal intensity in the bone marrow of the surgical margin immediately after the operation, the intensity had been normalized by degrees and there was no evidence of recurrence during a follow-up period of 34 months. This may suggest that bone marrow lesion showing abnormal intensity was edema rather than tumor invasion.

CONCLUSIONS

The authors conclude that total resection, including a bone marrow lesion, is not always necessary for benign osteoblastoma. Macroscopic findings that show an abnormal color tone of the cortex could be a good indicator in revealing tumor activity invading bone marrow.

Normal variants and frequent marrow alterations that simulate bone marrow lesions at MR imaging

MR imaging of the spine is routinely performed for the assessment of patients with spine-related symptoms and of patients with cancer. This article addresses normal variants and frequent alterations of the vertebral bone marrow that are encountered on MR imaging studies and can simulate lesions.

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.

Histologic assessment of peritumoral edema in soft tissue sarcoma

PURPOSE

To evaluate whether satellite tumor cells can be identified histologically in the tissues surrounding a soft tissue sarcoma and whether their presence correlates with increased T(2)-weighted signal intensity on MRI.

METHODS AND MATERIALS

Fifteen patients with a high-grade extremity or truncal soft tissue sarcoma underwent preoperative MRI. The extent of high T(2)-weighted signal changes in the tissues surrounding tumor, thought to represent peritumoral edema/reactive changes, was determined. Twelve patients received i.v. gadolinium, and contrast enhancement was determined. All patients underwent surgical resection in the absence of preoperative chemotherapy or radiotherapy. The presence of tumor cells in the surrounding tissues was determined histologically in representative paraffin-embedded sections and correlated with the MRI findings.

RESULTS

The extent of peritumoral T(2)-weighted MRI signal changes ranged from 0 to 7.1 cm (mean, 2.5 cm); contrast enhancement ranged from 0 to 5.3 cm (mean, 1.1 cm). Sarcoma cells were identified histologically in the tissues beyond the tumor in 10 of 15 cases. In 6 cases, tumor cells were located within 1 cm of the tumor margin, and in 4 cases, malignant cells were found at a distance >1 cm and up to a maximum of 4 cm. The location of tumor cells beyond the margin did not correlate with tumor size nor did it correlate with the location or extent of peritumoral changes.

CONCLUSION

The ability to identify tumor cells beyond the margin of a soft tissue sarcoma has important implications in planning appropriate targets for treatment. This could influence the use of new radiotherapy technologies such as intensity-modulated radiotherapy that aim to minimize treatment volumes through conformal planning.

Multiple vertebral fluid-fluid levels

We present a case of multiple vertebral metastases, with multiple fluid-fluid levels, from a moderately to poorly differentiated carcinoma of unknown origin. We suggest that fluid-fluid levels in multiple vertebral lesions are highly suggestive of bone metastases.

Can bone marrow edema be seen on STIR images of the ankle and foot after 1 week of running?

PURPOSE

To evaluate whether initiation of running in sedentary individuals would lead to bone marrow edema on MR images, within the time span of 1 week.

MATERIALS AND METHODS

The feet of 10 healthy volunteers were imaged by MR imaging before and after running during 30 min a day for 1 week. The images were evaluated by consensus of 2 musculoskeletal radiologists who graded the presence of bone marrow edema on a 4-point scale. Edema scores and number of bones involved before and after running were compared statistically.

RESULTS

Edema was present on the baseline images in 3 subjects. After running edema showed an increase or was present in 5 subjects. The changes after running were statistically significant. Bones involved were the talus, calcaneus, navicular bone, cuboid bone, and 5th metatarsal.

CONCLUSION

Edema patterns can be seen in the feet of asymptomatic individuals. During initiation of running an increase of edema or development of new edema areas can be seen.

MR imaging with ultrasmall superparamagnetic iron oxide particles in experimental soft-tissue infections in rats

PURPOSE

To investigate the feasibility of macrophage magnetic resonance (MR) imaging in rats by using an experimental soft-tissue infection model.

MATERIALS AND METHODS

Thirteen rats with unilateral calf-muscle infection were imaged with a 4.7-T MR imager at an early chronic stage of infection (day 4 before contrast material injection, days 4-7 after injection). Eleven animals were imaged before and 3 and 24 hours after intravenous application of ultrasmall superparamagnetic iron oxide (USPIO), and eight animals were additionally imaged 48 hours and three animals 72 hours after USPIO application. Two infected rats served as controls. T1- and T2-weighted spin-echo and T2*-weighted gradient-echo sequences were applied. All animals were sacrificed, and histopathologic findings were correlated with findings on MR images. Electron microscopy was performed in two rats. For quantitative analysis, signal intensities on T2*-weighted images and T2 values on T2 maps were measured within regions of interest, and the temporal variation was analyzed by using the signed rank test.

RESULTS

Visualization of USPIO-loaded macrophages was most sensitive with a T2*-weighted sequence. USPIO distribution pattern and quantitative analysis of T2 and T2* effects 3 hours after USPIO application were significantly different (P <.05) from those at 24 and 48 hours, reflecting the dynamic transit of the particle accumulation from the intravascular to the intracellular compartment by means of macrophage phagocytosis. Local signal intensity alterations could be correlated with iron-loaded macrophages at histopathologic examination.

CONCLUSION

Activated macrophages in acute soft-tissue infection can be labeled with USPIOs and detected with MR imaging because of susceptibility effects.

Magnetic resonance imaging characteristics of bizarre parosteal osteochondromatous proliferation of the hand: a case report

Bizarre parosteal osteochondromatous proliferation (BPOP) is a reactive lesion of cortical bone. A case of fifth metacarpal BPOP with intramedullary inflammatory extension is shown by magnetic resonance imaging. Histologically the intramedullary extension showed fibrosis with inflammatory cell infiltration. The surrounding adipose tissue showed fibrosis, focal inflammatory cell infiltration, and vascular proliferation. It is important to recognize that BPOP can bear radiologic resemblance to malignant lesions or osteomyelitis when there is an intramedullary inflammatory extension. Preservation of cortical bone under the osteocartilaginous mass on T1-weighted magnetic resonance imaging, and homogenous intramedullary enhancement with gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), can be helpful for distinguishing BPOP from malignant lesions.

Osteoid osteoma and osteoblastoma of the spine: experiences with 22 patients

Osteoblastomas and osteoid osteomas of the spine are relatively rare bone-forming tumors. Between 1980 and 1999, nine patients with osteoid osteoma and 13 patients with osteoblastoma had surgery for their tumors. Four tumors were in the cervical spine, six tumors were in thoracic spine, 10 tumors were in the lumbar spine, and two tumors were in the sacrum. The average duration between onset of pain and surgery was 16.6 months in 12 patients treated in the 1980s and 8.6 months in 10 patients treated in the 1990s. Seventeen patients had scoliosis. In nine of 10 patients with magnetic resonance imaging scans, high signal intensity areas in the muscles and bone around the lesion were seen. Two of nine patients with osteoid osteoma and nine of 13 patients with osteoblastoma had neurologic disorders before treatment. All patients had open resection of the lesions. Two patients with osteoid osteoma had relapse because of incomplete resection, necessitating a second excision. In 16 of 17 patients with preoperative spinal deformity, the deformity improved during followup. With development of modern imaging techniques, exact surgical planning may become possible; however, in some cases, intraoperative complete resection of the lesion still is difficult.

The lumbar vertebral body and diskovertebral junction. Radio MR imaging anatomic correlations

Radiographs and MR images of spine specimens provide superb tomographic views of changes that involve the mineralized network and the medullary content of vertebral bodies. By illustrating changes in the balance between bone resorption and formation and between fat and nonfat marrow cells, these frozen images of the reality help us to understand normal variants and lesions that develop in osseous and articular diseases of the lumbar spine.

From the RSNA Refresher Courses. Radiological Society of North America. Evaluation of the marrow space in the adult hip

The adult pelvis and hip contain extensive marrow space in which a variety of processes may occur. Evaluation of this space requires an understanding of normal maturation and recognition that the marrow of the pelvis (axial skeleton) and that of the proximal femurs (appendicular skeleton) contain variable amounts of red and yellow marrow. At magnetic resonance (MR) imaging, this variability yields patterns in normal marrow ranging from very uniform and homogeneous signal intensity to patchy and heterogeneous signal intensity. The marrow space serves as a reflection of patient health and may herald developing anemia with reconversion of inactive to active marrow. Pathologic processes to be considered include marrow edema related to trauma, tumors, or infection; marrow ischemia and infarction; marrow infiltration from primary or secondary neoplasms or from infection; or complete loss of normal myeloid tissue in the marrow space. Each process can be effectively studied with MR imaging.

Magnetic resonance imaging in primary bone tumors

MRI plays a major role in the evaluation and treatment planning of bone tumors. It should be used following plain films and before biopsy. The MR appearance of most tumors is nonspecific; however, the entire extent of the tumor and its relationship to adjacent structures can be determined at MRI providing a road map for the surgeon. The role of dynamic enhancement is evolving and has not yet been determined.