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

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.

Hemothorax caused by costal exostosis injuring diaphragm: a case report and literature review

Background

Osteochondromas, also known as exostoses, are the most common benign tumors of bone and can be classified into isolated and multiple osteochondromas. A great majority of osteochondromas is asymptomatic, painless, slow-growing mass, and incidentally found. However, osteochondromas occurring in adolescence or in adult patients can grow in size and become symptomatic as a result of mechanical irritation of the surrounding soft tissues or peripheral nerves, spinal cord compression, or vascular injury.

Case presentation

We present a case of a 13-year-old girl with spontaneous hemothorax, the cause of which was identified by limited thoracotomy with the aid of video-assisted thoracic surgery to be bleeding from a diaphragmatic laceration incurred by a costal exostosis on the left sixth rib. Preoperative chest computed tomography (CT) depicted a bony projection arising from the rib and bloody effusion in the intrathoracic cavity, but was unable to discern the bleeding cause from the lung or the diaphragm. This case will highlight our awareness that costal exostosis possibly results in bloody pleural effusion. Meanwhile, English literatures about solitary costal exostosis associated with hemothorax were searched in PubMed and nineteen case reports were obtained. Combined our present case with available literature, a comprehensive understanding of this rare disease entity will further be strengthened.

Conclusions

Injury to the diaphragm is the primary cause of hemothorax caused by costal osteochondroma, including the present case. Thoracic CT scan can help establish a diagnosis of preoperative diagnosis of costal osteochondroma. Surgical intervention should be considered for those patients with symptomatic osteochondroma of the rib. Combined with our case and literature, prophylactic surgical removal of intrathoracic exostosis should be advocated even in asymptomatic patients with the presentation of an inward bony spiculation.

X-ray and MRI Correlation of Bone Tumors Using Histopathology As Gold Standard

Introduction

Bone tumors are a common pathology of the musculoskeletal system being frequently encountered by clinicians. Radiological workup is a mainstay in the diagnostic workup of bone tumors. This study aimed to highlight the importance of plain radiography and MRI in the diagnosis of bone tumors keeping histopathology as a gold standard. It is a descriptive validation study conducted in the Radiology Department of Pakistan Institute of Medical Sciences Islamabad.

Methodology

The study included 92 patients with suspected bone lesions. After taking a complete history and receiving informed written consent. X-rays radiographs and magnetic resonance imaging were performed. X-ray radiograph and magnetic resonance imaging parameters were recorded and compared with the histopathology of lesions as a standard.

Results

The mean age of patients was 30.50 ± 8.95 years. Of 92 patients examined on X-ray, 51 (55.4%) had lytic lesions, 34 (37.0%) had sclerotic lesions, and seven (7.6 %) had mixed lesions. MRI revealed the location of the lesion. There were 25 (27.2%) bone lesions in diaphysis, 19 (20.7%) in metaphysis, nine (9.8%) at meta-diaphysis, and 32 (34.8 %) in the meta-epiphyseal region. These findings were later on confirmed with histopathological results.

Conclusion

MRI can differentiate soft-tissue components and periosteal reactions. An X-ray radiograph can provide information about bony matrix and calcifications within tumors. After analysis of imaging findings and histopathological results, it is concluded that these modalities can be used to diagnose bone tumors with high diagnostic accuracy.

Malignant Bone Tumors Diagnosis Using Magnetic Resonance Imaging Based on Deep Learning Algorithms

Background and Objectives: Malignant bone tumors represent a major problem due to their aggressiveness and low survival rate. One of the determining factors for improving vital and functional prognosis is the shortening of the time between the onset of symptoms and the moment when treatment starts. The objective of the study is to predict the malignancy of a bone tumor from magnetic resonance imaging (MRI) using deep learning algorithms. Materials and Methods: The cohort contained 23 patients in the study (14 women and 9 men with ages between 15 and 80). Two pretrained ResNet50 image classifiers are used to classify T1 and T2 weighted MRI scans. To predict the malignancy of a tumor, a clinical model is used. The model is a feed forward neural network whose inputs are patient clinical data and the output values of T1 and T2 classifiers. Results: For the training step, the accuracies of 93.67% for the T1 classifier and 86.67% for the T2 classifier were obtained. In validation, both classifiers obtained 95.00% accuracy. The clinical model had an accuracy of 80.84% for training phase and 80.56% for validation. The receiver operating characteristic curve (ROC) of the clinical model shows that the algorithm can perform class separation. Conclusions: The proposed method is based on pretrained deep learning classifiers which do not require a manual segmentation of the MRI images. These algorithms can be used to predict the malignancy of a tumor and on the other hand can shorten the time of their diagnosis and treatment process. While the proposed method requires minimal intervention from an imagist, it needs to be tested on a larger cohort of patients.

"Do-not-touch" lesions of bone revisited

Incidental bone lesions are encountered frequently in day-to-day practice. Many of these lesions are indeterminate requiring referral to specialist centres for further characterisation with or without biopsy; however, as biopsy has its own drawbacks, not all lesions can be subjected to biopsy. The primary role of a radiologist in these situations is to characterise these lesions based on their imaging appearances into aggressive lesions requiring biopsy and non-aggressive lesions that do not require a biopsy. The term "do-not-touch lesion" is used to describe a lesion with typical radiographic appearances that can be characterised based on radiographic appearances alone without needing a biopsy. With recent advances in imaging, many incidental lesions can be characterised into do-not-touch lesions based on their imaging appearances alone using a single imaging technique or using a combination of imaging techniques and, less frequently, with the additional help of serological investigations, without the need for biopsy. Hence, the definition of do-not-touch lesions of bone needs a revisit. In this article, we attempt to redefine do-not-touch lesions of bone and propose an imaging-based classification for characterisation of these lesions.

Unusual location of osteochondroma in the temporal region in a patient with functional pituitary adenoma

Osteochondromas are common in the long bones and relatively rare in the head and neck regions. We herein report a case of a solitary temporal bone osteochondroma associated with a functional pituitary adenoma hypersecreting prolactin. The patient was a 48-year-old man with progressive, painless temporal swelling associated with gradual visual loss, gynaecomastia, erectile dysfunction, and loss of libido. A brain computed tomography scan with bone windows showed right temporal sessile bony expansion and a pituitary tumour. A pituitary function test revealed hyperprolactinaemia. His symptoms resolved with medical management, and excisional biopsy of the temporal tumour confirmed an osteochondroma. To the best of our knowledge, this is the first reported case of a solitary temporal bone osteochondroma with a functional pituitary adenoma hypersecreting prolactin.

Osteochondromas: An Updated Review of Epidemiology, Pathogenesis, Clinical Presentation, Radiological Features and Treatment Options

Osteochondroma, the most common benign bone tumor, is a projection on the external surface of the bone, which can be sessile or pedunculated. 85% of osteochondromas present as solitary lesions, while 15% occur in the context of hereditary multiple exostoses (HME), a genetic disorder that is inherited in an autosomal dominant manner. Although often asymptomatic, symptoms may eventuate from compression of adjacent vessels or nerves, fractures, osseous deformities, bursa formation, or malignant transformation. Cartilage cap thickness >2 cm in adults or >3 cm in children as well as new onset of pain or growth, or rapid growth of the lesion, especially after the closure of the growth plate, might reflect cancerous transformation. Surgical resection is indicated for symptomatic lesions, complications, cosmetic reasons or malignant transformation. Excision of the tumor with free margin is the treatment of choice. Local recurrence is less than 2% if complete resection is achieved.

Fluid-fluid Levels in Musculoskeletal Tumor Imaging

Fluid-fluid levels result from the separation of two fluids of differing densities within a cavernous space with the boundary between the two layers running in a horizontal plane at 90 degrees to the direction of gravity. Magnetic resonance imaging is the most sensitive imaging modality to identify fluid-fluid levels. Although the most common bone lesions containing fluid-fluid levels are aneurysmal bone cyst and telangiectatic osteosarcoma, fluid-fluid levels can be observed in a wide variety of bone and soft tissue lesions. Therefore, fluid-fluid levels cannot be considered diagnostic of any particular type of tumor and the diagnosis should be made on the basis of other clinical, radiological and pathological findings. This article summarizes the pathophysiology and imaging characteristics of fluid-fluid levels and discusses the differential diagnosis of tumors with this imaging sign.

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.

Paediatric bone lesions: diagnostic accuracy of imaging correlation and CT-guided needle biopsy for differentiating benign from malignant lesions

OBJECTIVE

To determine the sensitivity, specificity and accuracy of CT-guided needle biopsy (CT-NB) for distinguishing benign and malignant lesions in children with suspected primary bone tumours, and to assess the correlation between imaging diagnosis and final diagnosis.

METHODS

Retrospective review of children who underwent CT-NB of a suspected primary bone tumour between October 2016 and October 2019. Data collected included anatomical location, imaging diagnosis, type of needle, type of biopsy sample, CT-NB diagnosis, final diagnosis and post-procedural complications. The final diagnosis was established based on surgical histology or clinical/imaging follow-up.

RESULTS

125 patients met the inclusion criteria (68M, 57F: mean age 11 years; range 10 months-18 years). Biopsy was performed using a 10 cm Jamshidi needle (10G n = 96; 13 G n = 8); 14G Tru-Cut needle (n = 18); 14G Temno needle (n = 3). The commonest anatomical locations were the femur (n = 40), tibia (n = 25) and humerus (n = 16), while the commonest diagnoses were osteosarcoma (n = 35), CRMO (n = 15) and LCH (n = 14). A benign tumour was correctly identified on imaging in 100% of cases, and a malignant tumour in 95.8%. Sensitivity, specificity and diagnostic accuracy of CT-NB for distinguishing malignant from benign lesions were 98%, 100 and 99%. Of 24 indeterminate biopsy results, all that had a non-aggressive radiological appearance were benign. No immediate complications were recorded.

CONCLUSION

CT-NB represents a safe and very effective tool for differentiating benign and malignant lesions in children presenting with a suspected primary bone tumour. Suspected radiological diagnosis plays a pivotal role in the management of indeterminate biopsy results.

ADVANCES IN KNOWLEDGE

Paediatric bone tumours pose a significant diagnostic and therapeutic challenge. The interpretation of the imaging findings is essential for the successful management of indeterminate histological results.

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.

Digital Subtraction Angiography and Magnetic Resonance Imaging-Based Staging of Circulatory Obstruction in the Femoral Head During Osteonecrosis of the Femoral Head Development

INTRODUCTION

Nontraumatic osteonecrosis of the femoral head (NONFH) is a common and difficult disease in orthopedics. Magnetic resonance imaging (MRI) assessment of NONFH and bone marrow edema was combined with digital subtraction angiography (DSA) to evaluate the circulatory status of NONFH in different Association Research Circulation Osseous stages. Based on the circulatory obstruction status (venous stasis, arterial ischemia, and arterial occlusion), appropriate perioperative management was adopted to achieve hip joint preservation and effectively delay the time for total hip arthroplasty in young patients.

METHODS

From January 2013 to March 2019, 41 orthopedic patients were evaluated for medical imaging. Sixty-one ONFH cases were enrolled. The inclusion criteria include: (1) Clear diagnosis of osteonecrosis of the femoral head. (2) No history of infection in the affected hip, no history of hip surgery, and no congenital hip diseases. The patients enrolled in this study were 8 women and 33 men between the ages of 19 and 64 years (mean, 39.25 ± 8.90 years). Preoperative X-ray, computed tomography, MRI, DSA, and histological data were taken.

RESULTS

The combination of DSA and MRI can efficiently show blood supply changes in the femoral head of NONFH patients at different Association Research Circulation Osseous stages; and also can possibly reveal the causes and development of NONFH. Different stages of circulatory obstruction of the femoral head can be clearly distinguished and used to determine the required perioperative management, thus yielding successful surgical outcomes.

CONCLUSIONS

The existing classification systems do not fully reflect the progression of circulatory obstruction in ONFH. Each stage of NONFH development has its own characteristics circulatory obstruction. Early-stage NONFH displays characteristic venous stasis of the femoral head, whereas advanced stage NONFH is characterized by insufficient arterial blood supply to the femoral head. Corresponding NONFH treatment strategies should be considered based on their specific circulatory status. This work also provides guidance and recommendations for adopting corresponding femoral head preserving strategies for young patients in different NONFH circulatory status.

The Dixon technique for MRI of the bone marrow

Dixon sequences are established as a reliable MRI technique that can be used for problem-solving in the assessment of bone marrow lesions. Unlike other fat suppression methods, Dixon techniques rely on the difference in resonance frequency between fat and water and in a single acquisition, fat only, water only, in-phase and out-of-phase images are acquired. This gives Dixon techniques the unique ability to quantify the amount of fat within a bone lesion, allowing discrimination between marrow-infiltrating and non-marrow-infiltrating lesions such as focal nodular marrow hyperplasia. Dixon can be used with gradient echo and spin echo techniques, both two-dimensional and three-dimensional imaging. Another advantage is its rapid acquisition time, especially when using traditional two-point Dixon gradient echo sequences. Overall, Dixon is a robust fat suppression method that can also be used with intravenous contrast agents. After reviewing the available literature, we would like to advocate the implementation of additional Dixon sequences as a problem-solving tool during the assessment of bone marrow pathology.

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.

Characterisation of musculoskeletal tumours by multivoxel proton MR spectroscopy

OBJECTIVE

The purpose of this study is to evaluate the role of multi-voxel proton MR spectroscopy in differentiating benign and malignant musculoskeletal tumours in a more objective way and to correlate the MRS data parameters with histopathology.

METHODS AND MATERIALS

A hospital-based prospective study was carried out comprising 42 patients who underwent MRI examinations from 1 July 2013 to 30 June 2014. After routine sequences, single-slice multi-voxel proton MR spectroscopy was included at TE-135 using the PRESS sequence. The voxel with the maximum choline/Cr ratio was used for analysis of data in 32 patients. The strength of association between the MR spectroscopy findings and the nature of tumour and histopathological grading were assessed.

RESULTS

Of the 42 patients, the MR spectra were not of diagnostic quality in 10. In the remaining 32 patients, 12 (37.5%) had benign and 20 (62.5%) malignant tumours. The mean choline/Cr ratio was 6.97 ± 5.95 (SD) for benign tumours and 25.39 ± 17.72 (SD) for malignant tumours. In our study statistical significance was noted between the choline/Cr ratio and the histological nature of musculoskeletal tumours (p = 0.002) assessed by unpaired t-test. The choline/Cr ratio and histological grading were also found to be significant (p = 0.001) when assessed by one-way ANOVA test.

CONCLUSIONS

Multi-voxel MR spectroscopy showed a higher choline/Cr ratio in malignant musculoskeletal tumours than in benign ones (p = 0.002). The choline/Cr ratio and histological grading of musculoskeletal tumours also showed statistical significance (p = 0.001).

Assessment of Musculoskeletal Malignancies with Functional MR Imaging

Functional MR imaging is the technique of choice to evaluate and manage malignant musculoskeletal masses. Advanced MR imaging sequences include chemical shift MR imaging, diffusion-weighted imaging with apparent diffusion coefficient mapping, MR spectroscopy imaging, and dynamic contrast-enhanced perfusion imaging. Functional MR imaging adds value to morphologic sequences in the detection, characterization, staging, and posttherapy assessment of malignant musculoskeletal malignancies. This article reviews the technical role of each functional sequence and their clinical applications to allow more confident decisions to be made. Multiparametric analysis of functional and anatomic MR sequences allows musculoskeletal tumors analysis to be improved.

The role of magnetic resonance imaging in the evaluation of bone tumours and tumour-like lesions

Bone tumours and tumour-like lesions are frequently encountered by radiologists. Although radiographs are the primary screening technique, magnetic resonance imaging (MRI) can help narrow the differential or make a specific diagnosis when a lesion is indeterminate or shows signs of aggressiveness. MRI can extend the diagnostic evaluation by demonstrating several tissue components. Even when a specific diagnosis cannot be made, the differential diagnosis can be narrowed. MRI is superior to the other imaging modalities in detecting bone marrow lesions and tumoral tissue (faint lytic/sclerotic bone lesions can be difficult to visualise using only radiographs). Contrast-enhanced MRI can reveal the most vascularised parts of the tumour and MRI guidance makes it possible to avoid biopsing necrotic areas. MRI is very helpful in local staging and surgical planning by assessing the degree of intramedullary extension and invasion of the adjacent physeal plates, joints, muscle compartments and neurovascular bundles. It can be used in assessing response to neoadjuvant therapy and further restaging. The post-therapeutic follow-up should also be done using MRI. Despite the high quality of MRI, there are a few pitfalls and limitations of which one should be aware. Applications of MRI in bone tumours will probably continue to grow as new sequences are further studied.

TEACHING POINTS

• When a lesion is indeterminate or shows signs of aggressiveness, MRI is indicated. • When MRI does not lead to a diagnosis, biopsy is indicated. • MRI is superior to the other imaging modalities in detecting bone marrow lesions. • MRI is very helpful in local staging and surgical planning. • MRI is used in assessing the response to neoadjuvant therapy, restaging and post-therapeutic follow-up.

MRI Characterization of Vascular Spinal Tumors

STUDY DESIGN

Randomized trial.

OBJECTIVE

This study described practical magnetic resonance imaging (MRI) characteristics to assist in the identification of these tumors including the corresponding statistics.

SUMMARY OF BACKGROUND DATA

Identification of vascular spinal tumors using MRI allows the opportunity for angiography and preoperative embolization (PE) to improve outcomes and decrease hemorrhage. The MRI characterization reliability of these tumors has not been described.

MATERIALS AND METHODS

A retrospective comparison of 40 patients, at a single institution, with known spinal tumors was conducted with 20 vascular versus 20 nonvascular cases (based on postoperative pathology). Randomized MRI T1 precontrast/postcontrast and T2 images of these tumors were blinded and reviewed by 7 spine surgeons and 5 musculoskeletal radiologists. Four criteria were reviewed: T2 hyperintensity, contrast enhancement, flow voids, and feeding vessels. The clinical relevance was evaluated by asking if the reviewer recommended PE.

RESULTS

The specificity, sensitivity, and accuracy of each characteristic for surgeons were: T2 hyperintensity (65%, 85%, 75%), contrast enhancement (84%, 38%, 61%), flow voids (42%, 86%, 64%), and feeding vessels (35%, 90%, 63%). The results for the radiologists were: T2 hyperintensity (83%, 61%, 72%), contrast enhancement (87%, 32%, 60%), flow voids (44%, 93%, 69%), and feeding vessels (33%, 93%, 63%). Both the groups had low κ and intraclass correlation values. Review of angiography/PE recommendation showed that both surgeons and radiologists had a false-negative rate of 33%.

CONCLUSIONS

Surgeons and radiologists have similar moderate accuracy of MRI vascularity identification. Radiologists have a higher sensitivity, but lower specificity. Even with simplified, straightforward criteria, the MRI characterization of vascular spinal tumors has low interobserver/intraobserver reliability with a false-negative rate for angiography/PE recommendation of 33%. Angiography may become more standard in the workup of spine tumors.

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.

[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.

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.

Relevance of MRI in prediction of malignancy of musculoskeletal system--a prospective evaluation

Background

The purpose of this study is to evaluate the role of MRI in musculoskeletal tumours, especially, in prediction of malignancy & to compare whether the diagnosis made on MRI correlates with the cytological/histopathological diagnosis.

Methods

50 consecutive patients presenting in the Outpatient and Inpatient department of the Department of Orthopaedics or Casualty of Jawaharlal Nehru Medical College and Hospital, AMU, Aligarh, India were included in this study. They were subjected to MR examination on 1.5 Tesla superconducting system (MAGNETOM Avanto, Siemens). After localizer sequences, T1W and STIR images were obtained in longitudinal planes followed by T2W and post contrast T1W images in axial planes. Additional sequences were taken when required. Various imaging characteristics of tumours were evaluated statistically and their respective sensitivity and specificity in prediction of malignancy were obtained.

Results

Features associated with benign diagnosis in a large percentage of cases, are size less than 8 cm, sharp margination, homogeneous T2 signal, absence of oedema, necrosis, calcification and fluid-fluid levels. Similarly, malignant tumours are commonly associated with presence of irregular margins, inhomogeneous signal intensity, oedema, necrosis, haemorrhage, fascial penetration, bone changes and neurovascular involvement. A correct histological diagnosis is reached on the basis of imaging studies alone in 65% to 75% of cases. The sensitivity for a MRI diagnosis of malignant tumour was 95% and specificity was 84%.

Conclusion

Differentiation of malignant from benign lesions of musculoskeletal system is best made by a combination of clinical and imaging parameters rather than by any single MR characteristic. When a lesion has a non-specific MR imaging appearance, it is useful to formulate a suitably ordered differential diagnosis based on tumour prevalence, patient age, and anatomic location. A systematic approach markedly improves diagnostic results.

MR imaging of primary bone tumors and tumor-like conditions in children

This article provides a review of the MR imaging features of the major primary malignant and benign bone tumors and tumorlike conditions encountered in the pediatric population. Malignant tumors discussed include osteosarcoma, Ewing sarcoma, chondrosarcoma, lymphoma, and malignant fibrous histiocytoma. Benign lesions discussed include simple bone cysts, aneurysmal bone cysts, giant cell tumor, osteochondroma, enchondroma, chondroblastoma, osteoid osteoma, osteoblastoma, nonossifying fibroma, fibrous dysplasia, osteofibrous dysplasia, hemangioma, and histiocytosis. The use of MR imaging in the diagnosis of these lesions is discussed, and the text is enhanced with imaging examples of the lesions.

Combined dynamic contrast-enhancement and serial 3D-subtraction analysis in magnetic resonance imaging of osteoid osteomas

The purpose of this study was to retrospectively correlate the results of dynamic contrast-enhanced magnetic resonance imaging (MRI) with histological and clinical diagnoses in patients with osteoid osteomas. Fifty-four patients with the MR diagnosis of osteoid osteoma were studied. MRI (1.5 Tesla) consisted of thin-section STIR sequences, dynamic 3D T1 gradient echo sequences during application of contrast material, and high-resolution postcontrast T1 spin echo sequences with fat saturation (maximum voxel size 0.6 x 0.6 x 3.0 mm). Evaluation was focused on serial image subtraction during the early phase after contrast injection and on time-intensity curves. The surrounding edema was helpful in finding the nidus in each lesion. In 49 of 54 patients (90.7%), the diagnosis of osteoid osteoma was certain or highly probable (sensitivity 1.0, positive predictive value 0.91). A total of 38 of 54 osteoid osteomas were histologically proven. Five MRI diagnoses were regarded as false positives. A similar proportion has been reported for computed tomography. Tailored high-resolution MR examinations with dynamic contrast enhancement can reliably diagnose osteoid osteomas and exactly localize the nidus without radiation exposure. We propose a stepwise approach with STIR sequences, dynamic contrast-enhanced scanning, and high-resolution postcontrast T1 spin echo sequences with fat saturation.

Promises and challenges of positron emission tomography for assessment of sarcoma in daily clinical practice

A correct histological diagnosis, careful staging and detection of tumour response to treatment are all crucial in the management of sarcomas. Imaging is important in all of these stages. Sarcomas have distinct biological and treatment-related features posing challenges for imaging. For example, size measurements may not adequately reflect response rates. Techniques which can measure tissue function rather than generate merely anatomical data such as positron emission tomography (PET) are rapidly gaining interest. We discuss the importance of imaging in different stages of patient management, emphasising the unique characteristics of sarcoma. Furthermore, we discuss the potential of PET for the various indications, focussing on therapy evaluation.