Staging of intraosseous extent of osteosarcoma: correlation of preoperative CT and MR imaging with pathologic macroslides

Self-supervised tumor segmentation and prognosis prediction in osteosarcoma using multiparametric MRI and clinical characteristics

BACKGROUND AND OBJECTIVE

Osteosarcoma has a high mortality among malignant bone tumors. MRI-based tumor segmentation and prognosis prediction are helpful to assist doctors in detecting osteosarcoma, evaluating the patient's status, and improving patient survival. Current intelligent diagnostic approaches focus on segmentation with single-parameter MRI, which ignores the nature of MRI resulting in poor performance, and lacks the connection with prognosis prediction. Besides, osteosarcoma is a rare disease, and their few labeled data may lead to model overfitting.

METHODS

We propose a three-stage pipeline for segmentation and prognosis prediction of osteosarcoma to assist doctors in diagnosis. First, we propose the Multiparameter Fusion Contrast Learning (MPFCLR) algorithm to share pre-training weights for the segmentation model using unlabeled data. Then, we construct a multiparametric fusion network (MPFNet), which fuses the complementary features from multiparametric MRI (CE-T1WI, T2WI). It can automatically segment tumor and necrotic regions. Finally, a fusion nomogram is constructed by segmentation masks and clinical characteristics (volume, tumor spread) to predict the patient's prognostic status.

RESULTS

Our experiments used data from 136 patients at the Second Xiangya Hospital in China. According to experiments, the MPFNet achieves 84.19 % mean DSC and 84.56 % mean F1-score in segmenting tumor and necrotic regions, surpassing existing models and single-parameter MRI input for osteosarcoma segmentation. Besides, MPFCLR improves the segmentation performance and convergence speed. In prognosis prediction, our fusion nomogram (C-index: 0.806, 95 %CI: 0.758-0.854) is better than radiomics (C-index: 0.753, 95 %CI: 0.685-0.841) and clinical (C-index: 0.794, 95 %CI: 0.735-0.854) nomograms in predictive performance. Compared to the comparison models, our model is closest to the prediction model based on physician annotations. Moreover, it can accurately distinguish the patients' prognostic status with good or poor.

CONCLUSION

Our proposed solution can provide references for clinicians to detect osteosarcoma, evaluate patient status, and make personalized decisions. It can reduce delayed treatment or overtreatment and improve patient survival.

Pediatric Osteosarcoma: Correlation of Imaging Findings with Histopathologic Features, Treatment, and Outcome

Osteosarcoma is the most common primary bone sarcoma in children. Imaging plays a pivotal role in diagnostic workup, surgical planning, and follow-up monitoring for possible disease relapse. Survival depends on multiple factors, including presence or absence of metastatic disease, chemotherapy response, and surgical margins. At diagnosis, radiography and anatomic MRI are used to characterize the primary site of disease, whereas chest CT and whole-body bone scintigraphy and/or PET are used to identify additional sites of disease. Treatment starts with neoadjuvant chemotherapy, followed by en bloc tumor resection and limb reconstruction, and finally, adjuvant chemotherapy. Preoperative planning requires precise tumor delineation, which traditionally has been based on high-spatial-resolution anatomic MRI to identify tumor margins (medullary and extraosseous), skip lesions, neurovascular involvement, and joint invasion. These findings direct the surgical approach and affect the options for reconstruction. For skeletally immature children, the risk of cumulative limb-length discrepancy and need for superior longevity of the reconstruction have led to the advent and preferential use of several pediatric-specific surgical techniques, including rotationplasty, joint preservation surgery, autograft or allograft reconstruction, and extendible endoprostheses. A better understanding of the clinically impactful imaging features can directly and positively influence patient care. Online supplemental material is available for this article. ^©RSNA, 2022.

Limited utility of intraoperative frozen sections in primary malignant tumours involving long bones - A multicenter analysis of 475 cases

Background

In the surgical removal of primary malignant tumours involving long bones, intraoperative frozen sections are used to ascertain the adequacy of tumour clearance. However, with the improved imaging modalities that provide better foreknowledge of the tumour extent, it is possible that the arduous task of performing frozen sections can be safely avoided. This would not only save procedural time but also reduce hospital costs. Presently, there are no clear guidelines regarding the modality required intraoperatively to assess tumour margins in these cases. Hence, in our retrospective multicentre analysis, we aimed at determining the usefulness of frozen sections in these cases.

Materials and methods

Our study is a 3-centre retrospective analysis of 475 cases (513 tumour margins) involving the surgical removal of primary malignancies of long bones. The preoperative Magnetic Resonance Imaging (MRI) and intraoperative assessment of the split specimen of the tumours were used to determine marginal clearance in all the cases in addition to frozen sections in 410 of the margins.

Results

Of the 410 frozen sections (centres 1 and 2), only one margin was reported positive and another reported indeterminate. All other margins were reported negative. In the first case, a 2 cm additional bone-cut was done whereas in the second, the procedure was proceeded based on the intraoperative agreement without re-cutting the margin. All these margins were negative in the final histopathology. In addition, in Centre 3, where frozen sections were not available, all the 103 cases had negative margins in the final histopathology.

Conclusion

In primary malignancies involving long bones, intraoperative decision making with the aid of MRI has been sufficiently accurate in identifying the required tumour margin without frozen sections. Hence, the added time and cost incurred by doing an additional procedure can be avoided in these cases.

•

Currently, there are no guidelines on the optimal marginal thickness required for tumour clearance in long bone tumours.

•

Our frozen section study analysed the correlation between frozen sections and final histopathology results.

•

Only 1 positive frozen smear was seen which was negative in the histopathology showing limited utility of frozen sections.

Accuracy of X-Ray and Magnetic Resonance Imaging in Defining the Tumor Margin in Primary Bone Sarcoma

BACKGROUND

Limb-salvage surgery for primary bone sarcomas are preceded by X-ray and MRI for surgical planning. However, the accuracy of X-ray and MRI predicted margins are not well described. Our study examined these questions: (1) How accurately do X-ray and MRI margin measurements reflect the true margin on pathology reports? (2) Do X-ray or MRI margin measurements have smaller differences compared to pathology reports? (3) How many X-ray or MRI margin measurement differences were greater than 1 cm, 2 cm, and 3 cm from pathology reports? (4) Is there an X-ray or MRI view that consistently results in a smaller difference from pathology reports?

METHODS

This retrospective chart review examined patients with primary bone sarcoma treated with limb-salvage surgery. Reviewers used electronic measurement tools to determine margins from X-ray or MRI based on the resection length of the pathologic specimen. Mean differences of margin measurements to pathology reports were calculated. We determined outliers of imaging margin measurements at 1 cm, 2 cm, and 3 cm differences to pathology reports.

RESULTS

In the total cohort of 39 patients, the mean difference of X-ray and MRI margins compared to pathology reports were 1.09 cm (st dev 0.79 cm) and 0.71 cm (st dev 0.70 cm), respectively. MRI margin measurements had smaller differences compared to pathology reports than X-ray in 32 of 38 cases (84%) with complete imaging. X-ray outliers at 1 cm, 2 cm, and 3 cm differences were 36, 14 and 2 respectively for 70 margin measurements and MRI outliers at 1 cm, 2 cm, and 3 cm differences were 17, 6, and 0 respectively for 66 margin measurements. The views with the smallest difference were anterior-posterior X-rays and MRI views with the closest predicted margin.

CONCLUSION

Electronic MRI margin measurements with the closest predicted margin provided the smallest differences with pathology reports and are therefore the most accurate for preoperative planning. When there is adequate residual diaphysis for reconstructive fixation, surgeons should plan for a 3 cm bone margin using MRI measurements to ensure complete removal of the intramedullary extent of sarcoma.Level of Evidence: IV.

Proximal femur sarcomas with intra-articular disease-Do intra-articular resections provide adequate local control?

BACKGROUND AND OBJECTIVES

Hip preserving (intra-articular) resections for proximal femur sarcoma have better function compared to peri-acetabular (extra-articular) resections, which are more complex and morbid. But, do intra-articular resections in selected cases with intra-articular disease provide adequate local control?

METHOD

Extra-articular resection or intra-articular resection in cases without pathologic fracture or away from joint/capsule was classified as a planned safe margin (SM). Circumferential removal of labrum without acetabular resection in cases without gross joint contamination was classified as planned close margins (CM). We analyzed local recurrence-free survival (LRFS) (death as a competing event) for 86 proximal femur resections (SM = 55, CM = 31).

RESULTS

The 5 years LRFS was 84% (n = 6/55, 10%) in the SM group and 67% (n = 4/31, 12%) in the CM group. There was no worsening of local recurrence (LR) in the CM group (subdistribution hazard [sH] = 0.69; 95% confidence interval [CI], 0.21-2.29; P = .56). Poor chemotherapy-induced necrosis predicted worse LR (sH = 0.1; 95% CI, 0.01-0.8; P = .03). Overall survival was 16% (SE 8%) at 5 years with LR vs 64% (SE 7%) without LR (P = .0076).

CONCLUSION

In proximal femur sarcomas with potential for involvement of the hip joint, a CM in selected cases did not worsen LR; providing an option for avoiding additional morbidity with extra-articular resections.

Clinical Significance of the Radiological Relationship between the Tumor and the main blood vessels in Enneking IIB Osteosarcoma of the extremities

Aim: Osteosarcoma is one of the most prevalent primary bone malignancies in children and adolescents. Magnetic resonance imaging (MRI) has been considered a very critical tool to provide anatomical information of tumor and surrounding main blood vessels. To evaluate the prognostic significance of the radiological vascular involvement according to the pre-treatment MRI in patients with Enneking IIB osteosarcoma. Methods: In this retrospective study, we included 482 patients younger than 50 years old with Enneking IIB primary osteosarcoma of the extremities with complete clinical records from 2005 to 2015.Univariate and multivariable analyses were conducted to identify the risk factors for OS (Overall survival) and EFS (Event-free survival). The correlations between the risk factors was performed using Spearman analysis. The Kaplan-Meier method was used to calculate survival curves. Based on the radiological relationship between the tumor lesion and the surrounding reactive area with the main blood vessels as shown on pretreatment MRI findings. Results: Radiological vascular involvement assessed via pretreatment MRI is an important risk factor for Enneking IIB primary patients with osteosarcoma (HR_OS=2.32/HR_EFS=1.81 P<0.01) according to the univariate and multivariable analyses. Enneking IIB patients with osteosarcoma were assigned to three subtypes based on the radiological relationship between the main blood vessels and the lesion or reactive area. The 5-year cumulative OS of patients classified by the three types were 81.6% (type I), 67.1% (type II) and 44.8% (type III)(P<0.01). The 5-year cumulative EFS of the three types were 60.2% (type I), 46.7% (type II) and 30.2% (type III)(P<0.05). The total 5-year cumulative OS and EFS for all patients were 68.3% and 48.3%, respectively. Conclusion: Vascular involvement according to radiological findings from pretreatment MRI is an independent risk factor for cumulative OS and EFS in patients with Enneking IIB primary osteosarcoma of the extremities. The new subtyping based on the relationship between the tumors and surrounding reactive area with the main blood vessels based on pretreatment MRI can predict the prognosis of patients with osteosarcoma and provide certain directive information for selecting the appropriate surgical procedure for individual patients.

Comparison of MRI and Histopathology with regard to Intramedullary Extent of Disease in Bone Sarcomas

In today's era, limb salvage surgery is the procedure of choice and current standard of care in appropriately selected patients of bone sarcomas. For adequate oncologic clearance, preoperative evaluation of the extent of tumor is mandatory. The present study was done to compare measurements of bone sarcomas (osteosarcoma, Ewing's sarcoma, and chondrosarcoma) as determined by magnetic resonance imaging (MRI) with the histopathological extent seen on resected specimens. We prospectively evaluated 100 consecutive patients with a diagnosis of bone sarcoma who underwent limb salvage surgery between May 2014 and December 2014. The maximum longitudinal (cranio-caudal) dimension of tumor on the noncontrast T1-WI sequence of MRI (irrespective of whether it was pre/postchemotherapy) was compared with the gross dimensions of the tumor on histopathology. The arithmetic mean difference, Wilcoxon signed-rank test, and Spearman's correlation analysis were used to test the differences and correlation between groups. Mean tumor size on MRI based on the largest extent on MRI was 12.1 ± 4.85 cm (mean ± standard deviation), while it was 10.77 ± 4.6 cm (mean ± standard deviation) on histopathology. In 79 cases, MRI overestimated the extent of disease; the mean was 1.79 cm with a standard deviation of 1.56 cm. When the disease extent was underestimated on MRI (13 cases), the mean was 0.58 cm with a standard deviation of 0.43 cm. In 8 cases (osteosarcoma (7), Ewing's sarcoma (1)), MRI measurement was equal to histopathology. The Spearman correlation analysis showed a high correlation of tumor length on histopathology with the MRI for all patients (R = 0.948, P < 0.0001). We thus conclude that MRI is accurate in delineating the extent of bone sarcomas. A margin of 2 cm from the maximum tumor extent is adequate to ensure appropriate surgical resection.

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.

Inter-rater Variability in the Interpretation of Pre and Post Contrast MRI for Pre-Surgical Evaluation of Osteosarcoma in Long Bones in Pediatric Patients and Young Adults

BACKGROUND AND OBJECTIVES

The value of gadolinium enhanced magnetic resonance imaging (MRI) sequences for extremity osteosarcoma resection planning is unverified. We evaluate the performance of intravenous gadolinium enhanced MRI for identification of neurovascular bundle involvement (NBI) and intraarticular extension (IAE) in patients with osteosarcoma.

METHODS

Two pediatric radiologists independently analyzed MRI examinations of patients with pathology proven extremity osteosarcoma for NBI and IAE. Initial evaluation utilized only non-contrast MRI images (PRE) and, after 2 weeks, subsequent evaluation included both the pre and post contrast images (POST). Cohen's Kappa and McNemar's test were calculated to assess agreement between PRE and POST image interpretations of NBI and IAE.

RESULTS

56 patients with 90 preoperative MRI examinations were analyzed. PRE and POST interpretations were rarely discordant; 4/90 cases for NBI (Kappa 0.91) and 2/90 cases for IAE (Kappa 0.95). McNemar's test did not show a difference between PRE and POST imaging (NBI p=0.62; IAE p=0.48).

CONCLUSION

No significant difference between PRE and POST image interpretation was found. A high level of agreement between PRE and POST image interpretation suggests that pre-contrast MRI may be sufficient for pre-surgical planning for pediatric patients with long bone osteosarcoma.

Magnetic Resonance Imaging for the Assessment of Long Bone Tumors

Background:

Wide resection margins of osseous tumors are associated with a low incidence of local recurrence, making accurate measurement of the intraosseous extent of primary malignant long bone tumors is crucial. We compared the intraosseous tumor extent assessed by magnetic resonance imaging (MRI) with the gross specimen to evaluate the accuracy of MRI.

Methods:

A total of 255 patients with primary malignant tumors in the long bones were included. Using MRI, we defined the length of tumor as the distance from the articular surface to the boundary between abnormal and normal marrow signal. The extent of the abnormal intraosseous signal was measured on unenhanced T1-weighted (T1WI) magnetic resonance images after chemotherapy. All gross surgical specimens were sectioned, and tumor extent was measured. Wilcoxon signed-rank test was used to test the differences between MRI and gross specimen findings. Spearman's correlation analysis was used to test the correlation between groups.

Results:

Median tumor length by gross specimen (112 mm; range, 45–300 mm) was longer than that by MRI (108 mm; range, 45–304 mm; Z = −6.916, P < 0.001). Of 255 images, tumor length was accurately represented on 27 T1WI magnetic resonance images, overestimated on 79 images, and underestimated on 149 images. The median difference between imaging and gross specimen measurements was 2.0 mm (range: 1.0–15.0 mm) for the 79 cases where tumor length was overestimated, and 5.0 mm (range: 1.0–18.0 mm) for the 149 cases where tumor length was underestimated. The Spearman correlation demonstrated a high correlation of tumor length on gross specimen with the tumor length on MRI (R = 0.99, P < 0.01).

Conclusions:

We conclude that preoperative MRI could be a useful method in determining intramedullary malignant bone tumor boundaries and may serve as an accepted assessment method of long bone tumors before limb-sparing surgery.

Proximal femoral osteosarcoma: Diagnostic challenges translate into delayed and inappropriate management

BACKGROUND

The proximal femuris is an uncommon site of osteosarcoma. The unusual manifestations at this site may lead to diagnostic and therapeutic mistakes. We therefore performed a retrospective study to estimate the proportions of patients with imaging study findings and/or clinical manifestations typical for osteosarcoma and/or inappropriate treatment decisions.

HYPOTHESIS

Proximal femoral osteosarcoma often produces atypical clinical and radiological presentations.

MATERIAL AND METHODS

Consecutive patients who underwent surgery at our center to treat proximal femoral osteosarcoma were included. For each patient, we collected the epidemiological characteristics, clinical symptoms, imaging study findings, treatment, and tumor outcome. Proportions were computed with their confidence intervals.

RESULTS

Twelve patients had surgery for proximal femoral osteosarcoma between 1986 and 2015. Imaging findings were typical in 1 (8%) patient; they consisted of ill-defined osteolysis in 11/12 (92%) patients, a periosteal reaction in 1/12 (8%) patient, soft tissue involvement in 7/12 (58%) patients, and immature osteoid matrix in 11/12 (92%) patients. No patient had the typical combination of pain with a soft tissue swelling. Management was inappropriate in 2/12 (17%) patients, who did not undergo all the recommended imaging studies before surgery and were treated in another center before the correct diagnosis was established. At last follow-up, 4 patients had died (after a mean of 7 years) and 8 were alive (after a mean of 4 years).

CONCLUSION

Proximal femoral osteosarcoma is uncommon and rarely produces the typical clinical and imaging study findings. The atypical presentation often results in diagnostic errors and inappropriate treatments. Ill-defined osteolysis on standard radiographs should prompt computed tomography or magnetic resonance imaging of the proximal femur. Treatment in a specialized center is imperative.

LEVEL OF EVIDENCE

IV, retrospective study.

Accuracy of Various MRI Sequences in Determining the Tumour Margin in Musculoskeletal Tumours

Background

It is imperative that bone tumour margin and extent of tumour involvement are accurately assessed pre-operatively in order for the surgeon to attain a safe surgical margin. In this study, we comprehensively assessed each of the findings that influence surgical planning, on various MRI sequences and compared them with the gold standard – pathology.

Material/Methods

In this prospective study including 21 patients with extremity bone tumours, margins as seen on various MRI sequences (T1, T2, STIR, DWI, post-gadolinium T1 FS) were measured and biopsies were obtained from each of these sites during the surgical resection. The resected tumour specimen and individual biopsy samples were studied to assess the true tumour margin. Margins on each of the MRI sequences were then compared with the gold standard – pathology. In addition to the intramedullary tumour margin, we also assessed the extent of soft tissue component, neurovascular bundle involvement, epiphyseal and joint involvement, and the presence or absence of skip lesions.

Results

T1-weighted imaging was the best sequence to measure tumour margin without resulting in clinically significant underestimation or overestimation of the tumour extent (mean difference of 0.8 mm; 95% confidence interval between −0.9 mm to 2.5 mm; inter-class correlation coefficient of 0.998). STIR and T1 FS post-gadolinium imaging grossly overestimated tumour extent by an average of 16.7 mm and 16.8 mm, respectively (P values <0.05). Post-gadolinium imaging was better to assess joint involvement while T1 and STIR were the best to assess epiphyseal involvement.

Conclusions

T1-weighted imaging was the best sequence to assess longitudinal intramedullary tumour extent. We suggest that osteotomy plane 1.5 cm beyond the T1 tumour margin is safe and also limits unwarranted surgical bone loss. However, this needs to be prospectively proven with a larger sample size.

[The value of MRI in the diagnosis of joint involvement in malignant primitive tumors of the knee]

INTRODUCTION

Surgical treatment of malignant primitive tumors of bone needs a precise preoperative assessment of tumor local extension. Joint involvement (JI) represents the most important finding to determine, for the choice of surgical procedure (intra- or extra-articular resection).

OBJECTIVE

To determine the value of different MR signs for the diagnosis of joint involvement in malignant primitive tumors of the knee.

METHODS

Ten-year period retrospective study of 42 patients. Patients' clinical and imaging data have been studied. Two senior musculoskeletal radiologists have blindly and consensually reviewed imaging data. Histopathological data have been reviewed by an experimented pathologist. The results have been compared using several statistical methods to determine the global and detailed (sign by sign) diagnostic value and accuracy of MRI by reference to histopathology.

RESULTS

Some MR signs were performant in the diagnosis of joint involvement. The most sensitive were epiphyseal extension (Se: 100%), osteochondral extension (Se: 87.5%) and extension to the tibial spines (Se: 83.3%). The most specific MR signs were the presence of an intra-articular mass (Sp: 84.62%), extension to the intercondylar notch (Sp: 80.77%) and longitudinal axis≥120mm (Sp: 84.62%).

CONCLUSION

A rigorous and reproducible MR technique has to be used, the knee being explored in the transversal, sagittal and coronal planes. MR conclusion has to be clear and simple (intact, doubtful or involved joint). MR interpretation has to consider tumoral extension pathways. In doubtful cases, CT may help in this diagnosis by studying the bone cortex.

LEVEL OF EVIDENCE

IV.

Marrow signal mimicking tumor on MRI T1-weighted imaging after neoadjuvant chemotherapy in extremity osteosarcomas

PURPOSE

Many studies had demonstrated that MRI T1-weighted imaging was the most accurate method to evaluate the intramedullary extent of extremity osteosarcoma. However, we found that after neoadjuvant chemotherapy new low signal of MRI T1 imaging was detected near tumor, which mimicked the tumor progression. The aim of this study was to describe the incidence and type of this new signal, to reveal the pathological correlation with this imaging change.

METHODS

We included 74 extremity osteosarcomas managed between June 2011 and November 2012 in this retrospective study. The T1-weighted MRI images of the affected extremity before and after neoadjuvant chemotherapy were reviewed and compared. The subjects were then classified according to the appearance of the border between the area involved by osteosarcoma and the normal marrow with attention paid to whether the border was continuous and the width of the zone of transition. The study population was classified into one of four classifications: 'clear', 'continuous diffuse', 'discontinuous island-like' and 'discontinuous diffuse'. 11 patients underwent MRI of bilateral extremities, and for these patients we assessed the appearance of the uninvolved extremity with that with osteosarcoma. Following surgical resection of the tumor, the pathologic appearance was compared with the pre-operative MRI findings.

RESULTS

According to our classification system, all 74 subjects were 'clear' before neoadjuvant chemotherapy. After neoadjuvant chemotherapy, 30 subjects (40.5%) were still clear. Of the 44 subjects (59.5%) not classified as 'clear', 22 (29.7%) were classified as 'continuous diffuse', 4 (5.4%) as 'discontinuous island-like', and 18 (24.3%) as 'discontinuous diffuse'. Of the subjects with MRI of bilateral femurs, no radiologic difference was noted in the normal marrow bilaterally. No significant difference in overall survival and relapse free survival was noted between patients grouped according to the subtypes of MRI noted.

CONCLUSIONS

Neoadjuvant chemotherapy for extremity osteosarcoma can result in a variety of changes of the MRI appearance of tumor and adjacent bone and marrow. Areas of signal change beyond the tumor that represent marrow conversion and not tumor progression appear on T1 weighted imaging to be lower in signal than subcutaneous fat and higher in signal than muscle. Recognizing the existence of the effect of neoadjuvant chemotherapy on the MR appearance of the tumor and surrounding bone and myeloid elements is important so as to plan for oncological sound tumor resections while avoiding resecting more normal bone than necessary.

Does Microwave Ablation of the Tumor Edge Allow for Joint-sparing Surgery in Patients With Osteosarcoma of the Proximal Tibia?

BACKGROUND

Joint-sparing surgery of a patient's native joint for osteosarcoma likely affords better function and comparable survival. However, it sometimes is challenging to resect a juxtaarticular osteosarcoma in a way that preserves the affected epiphysis because wide margins are necessary to minimize the risk of local recurrence. If there was a method to resect a tumor close to the joint and treat a potentially positive margin to prevent recurrence, it might allow salvage of a joint that otherwise might be lost.

QUESTIONS/PURPOSES

We therefore asked (1) whether joint-preserving tumor resection could be performed for juxtaarticular osteosarcoma after microwave ablation of the tumor edge under navigation without leading to local recurrences, (2) what is the resulting function, and (3) what are the complications associated with this procedure.

METHODS

Between 2009 and 2011, we treated 11 patients who had juxtaarticular osteosarcoma of the proximal tibia (mean age, 12 years; range, 9-16 years) with joint-preserving surgery by transepiphysis tumor resection after navigation-assisted microwave ablation of the tumor edge; they were followed a minimum of 37 months (mean, 48 months; range 37-62 months), and none was lost to followup. Patients were considered eligible for this procedure if they had a distance from the tumor edge to the articular surface between 10 to 15 mm, good chemotherapy responses, no pathologic fracture and no tumor involvement of major neurovascular structures. Allograft in combination with a vascularized fibula flap was used for segmental reconstruction. We recorded local tumor control, complications, and functional outcomes using the Musculoskeletal Tumor Society score, which ranges from 0 to 30, with higher scores indicating better function.

RESULTS

There were no local recurrences. Major complications included osteonecrosis of part of the epiphysis in two patients and deep infection in one. The Musculoskeletal Tumor Society score ranged from 26 to 30 with a mean of 29.

CONCLUSIONS

In selected patients with osteosarcoma invading the epiphysis, navigated resection facilitates performing joint-sparing surgery, and in our small series, the adjuvant microwave ablation seemed to provide adequate local tumor control. Although more experience and longer followup are needed, this approach may make it possible to salvage more native joints when performing limb salvage for osteosarcoma.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Influence of bony resection margins and surgicopathological factors on outcomes in limb-sparing surgery for extremity osteosarcoma

BACKGROUND

Limb-sparing surgery for osteosarcoma requires taking wide bony resection margins while maximizing preservation of native bone and joint. However, the optimal bony margin and factors associated with recurrence and survival outcomes in these patients are not well established.

PROCEDURE

We conducted a retrospective review of outcomes in children and adolescents with newly diagnosed osteosarcoma from 1986 to 2012, where bony resection margins for limb-sparing surgeries were decreased serially from 5 to 1.5 cm. The association between bony margins and other surgicopathological factors with survival and recurrence outcomes was determined.

RESULTS

In 181 limb-sparing surgeries in 173 patients, planned and actual bony resection margins were not significantly associated with local recurrence-free survival (LRFS), event-free survival (EFS), and overall survival (OS)-at median 5.8 years follow-up, decreasing planned bony resection margins from 5 to 1.5 cm did not significantly decrease survival outcomes. Multivariable analysis showed that the presence of distant metastases at diagnosis was associated with decreased LRFS, EFS, and OS (P = 0.002, 0.005, and <0.0001, respectively). Post-chemotherapy tumor necrosis ≤90% was associated with decreased EFS and OS (P = 0.001 and 0.022, respectively). Earlier years of treatment and pathologic fractures were associated with decreased OS only (P = 0.018 and 0.008, respectively); previous cancer history and male gender were associated with decreased EFS only (P = 0.043 and 0.023, respectively).

CONCLUSION

We did not observe significant increase in adverse survival outcomes with reduction of longitudinal bony resection margins to 1.5 cm. Established prognostic factors, particularly histologic response to chemotherapy and metastases at diagnosis, remain relevant in limb-sparing patients. Pediatr Blood Cancer 2015;62:246-251. © 2014 Wiley Periodicals, Inc.

Accuracy of magnetic resonance imaging in planning the osseous resection margins of bony tumours in the proximal femur: based on coronal T1-weighted versus STIR images

OBJECTIVE

Assessment of the extent of tumours using magnetic resonance imaging (MRI) is the basis for bone resection in limb-salvage surgery. We aimed to compare the accuracy of T1-weighted MRI and STIR sequences in measuring the extent of proximal femoral tumours, using the macroscopic specimens as the gold standard for comparison.

MATERIALS AND METHODS

We compared single coronal T1-weighted with STIR sequences in 34 proximal femoral tumours, using bivalved resected macroscopic tumours for comparison. After randomisation, four observers measured longitudinal osseous tumour extent using MRI and specimen photographs on two separate occasions, 3 weeks apart.

RESULTS

There were 25 metastatic tumours, 8 chondrosarcomas and 1 myeloma. Eight patients presented with pathological fractures. The Pearson's correlation coefficient for comparison of T1 with macroscopic tumours was 0.91 (95% confidence interval [CI]: 0.83 to 0.96) for all observers and 0.90 (95% CI: 0.81 to 0.95) for STIR images. This difference was not statistically significant, and T1 and STIR sequence measurements had similar precision and accuracy. Bland-Altman plots showed T1-weighted imaging to be unbiased, whereas STIR sequences were biased and had systematic error. Moreover, STIR measurements overestimated tumour size by 6.4 mm (95% CI: -26.9 to 39.7 mm) and 2 patients were outliers. T1 measurements were closer to the macroscopic measurements with a mean difference of 1.3 mm (95% CI: -28.9 mm to 31.5 mm), with 3 patients falling outside of this. The variance was greater for STIR measurements. This difference between T1 and STIR measurements was statistically significant (p = 0.000003). The intra-observer reliability between separate measurements for MRI and specimen photographs achieved interclass correlation coefficients of 0.97, 0.96 and 0.95 (T1, STIR and macroscopic tumour respectively). T1 had greater interobserver correlation than for STIR and macroscopic tumour measurements (0.88 vs 0.85 and 0.85 respectively). These differences in interclass correlation were not statistically significant.

CONCLUSION

This study has shown T1-weighted MRI sequences to be unbiased compared with STIR sequences at determining intra-osseous tumour extent. STIR overestimates the length of bone tumours. T1 is therefore preferred for pre-operative planning for the resection of bone tumours.

Chondroblastic osteosarcoma of the left zygomatic bone: Rare case report and review of the literature

Chondroblastic osteosarcoma (COS), a subgroup of intramedullary osteosarcoma (OS), is the most common osteosarcoma that occurs in adolescents and early adulthood. The COS has similar clinical and radiological features to those of conventional OS. We present a case of 20-year-old male patient with the chief complaint of pain and swelling in the left zygomatic region. The computed tomography (CT) and three-dimensional (3D) CT face showed erosion, calcific foci, sunray type of spicules suggestive of OS. On fine-needle aspiration cytology (FNAC) examination, initial diagnosis was malignant chondroid lesion, with differential diagnosis of mesenchymal chrondrosarcoma, COS on incisional biopsy and finally COS on excisional biopsy. The patient underwent radical resection of left zygomatic arch, followed by chemotherapy. Although clinically unsuspected in this unusual site, histopathology along with immunohistochemistry (IHC) results confirmed the COS. Because zygomatic location of COS is very rare, this report aimed to discuss clinical, radiographic, histopathologic, IHC findings and diagnostic pitfalls of COS in light of the literature.

Chemical shift imaging: preliminary experience as an alternative sequence for defining the extent of a bone tumor

OBJECTIVE

To investigate chemical shift imaging (CSI) with in-phase and opposed-phase (OP) gradient-echo sequences as an alternative sequence to spin-echo T1 imaging for defining intra-medullary skeletal tumor extent.

METHODS AND MATERIALS

This retrospective HIPAA-compliant study was approved by our institutional institutional review board (IRB). Twenty-three subjects with histologically-proven tumors (17 appendicular, 6 axial) underwent magnetic resonance imaging (MRI) with T1-weighted spin echo (T1SE), fluid-sensitive, CSI, and contrast-enhanced T1 sequences. One observer recorded intra-medullary tumor extent (millimeters), with 153 total measurements on each sequence. Red marrow grade [0 (none), 1 (<50%), 2 (50-75%) and 3 (>75%)] in each bone was recorded. Tumor extent on different sequences was compared (Student's t-test); the impact of red marrow grade on measurements was assessed (Spearman's correlation coefficient).

RESULTS

There was good agreement between measurements of tumor extent on T1SE and CSI sequences in all cases (T1SE-CSI measurement difference range 0-13.2 mm, P>0.05). Measurements from other sequences were significantly different from those of T1SE (P<0.05). As red marrow grade in the bone increased, a significant increase in measurement difference obtained on T1SE and CSI sequences was observed (P<0.001).

CONCLUSIONS

CSI is a potential alternative technique to T1SE imaging for defining the intra-medullary extent of a bone tumor, possibly especially useful in regions with abundant red marrow.

ADVANCE IN KNOWLEDGE

CSI could be an alternative technique to T1SE imaging for defining the intra-medullary extent of bone tumor by abundant red marrow in the surrounding bone.

Imaging of primary bone tumors: determination of tumor extent by non-contrast sequences

Magnetic resonance imaging (MRI) is the modality of choice for determining the extent of a primary bone tumor. This article will discuss the MRI techniques needed to accurately define the intramedullary extent of a bone sarcoma, emphasizing the need for non-contrast T1-weighted sequences and highlighting the role of chemical shift imaging.

Joint-preserving tumor resection and reconstruction using image-guided computer navigation

BACKGROUND

Joint-preserving surgery is performed in select patients with bone sarcomas of extremities and allows patients to retain the native joint with better joint function. However, recurrences may relate to achieving adequate margins and there is frequently little room for error in tumors close to the joint surface. Further, the tumor margin on preoperative CT and/or MR images is difficult to transpose to the actual extent of tumor in the bone in the operating room.

QUESTIONS/PURPOSES

We therefore determined whether joint-preserving tumor surgery could be performed accurately under image-guided computer navigation and determined local recurrences, function, and complications.

METHODS

We retrospectively studied eight patients with bone sarcoma of extremities treated surgically by navigation with fused CT-MR images. We assessed the accuracy of resection in six patients by comparing the cross sections at the resection plane with complementary prosthesis templates. Mean age was 17 years (range, 6-46 years). Minimum followup was 25 months (mean, 41 months; range, 25-60 months).

RESULTS

The achieved resection was accurate, with a difference of 2 mm or less in any dimension compared to that planned in patients with custom prostheses. We noted no local recurrence at latest followup. The mean Musculoskeletal Tumor Society score was 29 (range, 28-30). There were no complications related to navigation planning and procedures. There was no failure of fixation at the remaining epiphysis.

CONCLUSIONS

In selected patients, the computer-assisted approach facilitates precise planning and execution of joint-preserving tumor resection and reconstruction. Further followup assessment in a larger study population is required in these patients.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Effects of neoadjuvant chemotherapy on image-directed planning of surgical resection for distal femoral osteosarcoma

BACKGROUND

Standard therapy for localized osteosarcoma includes neoadjuvant chemotherapy preceding local control surgery, followed by adjuvant chemotherapy. When limb-salvage procedures were being developed, preoperative chemotherapy allowed a delay in definitive surgery to permit fabrication of custom endoprosthetic reconstruction implants. One rationale for its continuation as the care standard has been the perception that it renders surgery easier and safer. Our objective was to compare surgical procedures planned on the basis of magnetic resonance images (MRIs) of distal femoral osteosarcomas acquired before neoadjuvant chemotherapy with surgical procedures planned on the basis of MRIs acquired after neoadjuvant chemotherapy as a measure of the surgically critical anatomic effects of the chemotherapy.

METHODS

Twenty-four consecutive patients with distal femoral osteosarcoma had available digital MRIs preceding and following neoadjuvant chemotherapy. Thorough questionnaires were used to catalogue surgically critical anatomic details of MRI-directed surgical planning. Four faculty musculoskeletal oncologic surgeons and two musculoskeletal radiologists evaluated the blinded and randomly ordered MRIs. Interrater and intrarater reliabilities were calculated with intraclass correlation coefficients. The Student t test and chi-square test were used to compare pre-chemotherapy and post-chemotherapy continuous and categorical variables on the questionnaire. Mixed-effect regression models were employed to compare surgical procedures planned on the basis of pre-chemotherapy MRIs and with those planned on the basis of post-chemotherapy MRIs.

RESULTS

The blinded reviews generated strong intraclass correlation coefficients for both interrater (0.772) and mean intrarater (0.778) reliability. The MRI-planned resections for the majority of tumors changed meaningfully after chemotherapy, but in inconsistent directions. On the basis of mixed-effect regression modeling, it appeared that more amputations were planned on the basis of post-chemotherapy MRIs. No other parameters differed in a significant and clinically meaningful fashion. Surgeons demonstrated their expectation that neoadjuvant chemotherapy would improve resectability by planning more radical surgical procedures on the basis of scans that they predicted had been obtained pre-chemotherapy.

CONCLUSIONS

Surgeons can reliably record the anatomic details of a planned resection of an osteosarcoma. Such methods may be useful in future multi-institutional clinical trials or registries. The common belief that neoadjuvant chemotherapy increases the resectability of extremity osteosarcomas remains anecdotally based. Rigorous assessment of this phenomenon in larger cohorts and at other anatomic sites as well as re-evaluation of other arguments for neoadjuvant chemotherapy should be considered.

Magnetic resonance imaging is appropriate for determining the osteotomy plane for appendicular osteosarcoma after neoadjuvant chemotherapy

There are no standard criteria for determining a sufficient resection margin in the treatment of osteosarcoma. The purposes of this study are to evaluate clinical outcomes using T1-weighted magnetic resonance imaging (MRI) for determining the margin of resection and to compare that with the results of different imaging modalities. Seventeen patients diagnosed with osteosarcoma who underwent en bloc resection with a margin of 2-3 cm based on T1-weighted MRI following chemotherapy were studied. Imaging modalities including conventional radiography, MRI, computed tomography (CT), visual assessment, and histopathological examination were performed and compared. Survival rates were determined. After follow-up of 45.5 ± 13.8 months, no local tumor recurrence was observed in any patient. The 1-, 3-, and 5-year survival rates were 94.1, 82.3, and 76.5%, respectively. The differences in the measurement errors among the five methods were analyzed using pathology as the gold standard. Errors were smallest using T1-weighted and fat-suppressed MRI. There were no significant differences between the measurement results of postoperative histopathological examination and that of T1-weighted imaging or T2 fat-suppressed imaging. The measurement results of radiography and CT were significantly different from that of postoperative pathological findings (P < 0.05). Thus, MRI examination is superior to radiography and CT for determining tumor invasion in patients with osteosarcoma. A resection margin of 2-3 cm determined by MRI provides adequate treatment, while minimizing tissue removal.

Joint-sparing or physeal-sparing diaphyseal resections: the challenge of holding small fragments

BACKGROUND

Joint-sparing or physeal-sparing diaphyseal resections are technically challenging when only a small length of bone is available for implant purchase.

QUESTIONS/PURPOSES

We describe a series of cases with the aim of generating some guidelines as to the choice of reconstruction method and the implant used.

METHODS

We retrospectively reviewed 25 patients with diaphyseal resections in which the remaining epiphyseal or metaphyseal segment provided 3 cm or less of purchase. Reconstruction was performed with bone (allograft, extracorporeally radiated autograft, or vascularized fibula) in 19 cases or a custom diaphyseal implant (CDI) in six. The implants used for holding the bone construct varied from standard plates to custom plates. The presence of union, function, complications, and disease status at last followup was recorded.

RESULTS

Sixteen of the 25 patients are disease-free and alive with the original construct at a median followup of 34 months (range, 12-66 months). Implant-related complications such as plate breakage (four) and angulation (three) happened more frequently when weak plates such as reconstruction plates were used. Local recurrence with pulmonary metastases occurred in two cases. The two deep infections required an amputation or rotationplasty for control. Custom plates were successful in three of four patients.

CONCLUSIONS

Weak plates such as reconstruction plates are best avoided for these reconstructions. Custom plates allow secure fixation with technical ease. CDIs allow immediate weightbearing and ability to lengthen with predictable good functional short-term outcome.

The influence of tumor- and treatment-related factors on the development of local recurrence in osteosarcoma after adequate surgery. An analysis of 1355 patients treated on neoadjuvant Cooperative Osteosarcoma Study Group protocols

BACKGROUND

Local recurrence (LR) in osteosarcoma is associated with very poor prognosis. We sought to evaluate which factors correlate with LR in patients who achieved complete surgical remission with adequate margins.

PATIENTS AND METHODS

We analyzed 1355 patients with previously untreated high-grade central osteosarcoma of the extremities, the shoulder and the pelvis registered in neoadjuvant Cooperative Osteosarcoma Study Group trials between 1986 and 2005. Seventy-six patients developed LR.

RESULTS

Median follow-up was 5.56 years. No participation in a study, pelvic tumor site, limb-sparing surgery, soft tissue infiltration beyond the periosteum, poor response to neoadjuvant chemotherapy, failure to complete the planned chemotherapy protocol and biopsy at a center other than the one performing the tumor resection were significantly associated with a higher LR rate. No differences were found for varying surgical margin widths. Surgical treatment at centers with small patient volume and additional surgery in the primary tumor area, other than biopsy and tumor resection, were significantly associated with a higher rate of ablative surgery.

CONCLUSIONS

Patient enrollment in clinical trials and performing the biopsy at experienced institutions capable of undertaking the tumor resection without compromising the oncological and functional outcome should be pursued in the future.

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.

Surgical management of pelvic sarcoma in children

Survival rates of children with pelvic sarcoma have demonstrated unprecedented improvement during the past few decades, with a corresponding increase in the number of limb-sparing surgical procedures being performed. This increase may be attributed to earlier detection with advanced imaging techniques, the availability of a wider armamentarium of surgical techniques of reconstruction and limb salvage, and advances achieved in neoadjuvant chemotherapy and radiation therapy. Undertaking reconstruction after resection of pelvic sarcoma while preserving function of the hip and limb can be extremely challenging; this is especially true in children, who invite concern regarding growth potential and limb-length discrepancy. Decisions for surgery and reconstruction are individualized based on tumor type, size, and location as well as the probability of achieving a wide resection with negative margins and acceptable morbidity.

Osteosarcoma near joints: assessment and implications

BACKGROUND

The choice of performing surgery when tumors encroach onto joints remains a challenging and controversial issue. Pre-operative assessment by magnetic resonance imaging (MRI) is of critical importance in dictating surgical management and subsequent functional outcome.

METHODS

We examined archival samples from 27 patients with osteosarcoma, adjacent to synovial joints for the incidence and mechanism of osteosarcoma extension into the joint space. Histopathologic findings were correlated with pre-operative MRI findings and choice of operation.

RESULTS

There was no evidence of penetration across the entire thickness of articular cartilage into the joint cavity in all of the 27 cases. When pre-operative MRI confidently excluded joint involvement by tumor, enabling an intra-articular surgical approach, histopathologic correlation confirmed the absence of joint involvement in all cases. The low incidence of joint involvement was despite the presence of extensive bone and soft tissue involvement in most cases, a tendency for peripheral extension of tumor around the articular margin of the bone, and evidence of joint effusions pre-operatively in more than one-third of cases.

CONCLUSIONS

Joint involvement by osteosarcoma is uncommon, with articular cartilage being a relative barrier to tumor invasion. If pre-operative MRI does not show definite evidence of intra-articular tumor involvement, it is likely to be safe to proceed with intra-articular resection.

Biology and therapeutic advances for pediatric osteosarcoma

Osteosarcoma is the most common malignant bone tumor in children and adolescents. Survival for these patients was poor with the use of surgery and/or radiotherapy. The introduction of multi-agent chemotherapy dramatically improved the outcome for these patients and the majority of modern series report 3-year disease-free survival of 60%-70%. This paper describes current strategies for treating patients with osteosarcoma as well as review of the clinical features, radiologic and diagnostic work-up, and pathology. The authors review the state of the art management for patients with osteosarcoma in North America and Europe including the use of limb-salvage procedures and reconstruction as well as discuss the etiologic and biologic factors associated with tumor development. Therapy-related sequelae and future directions in the biology and therapy for these patients are also discussed.

Imaging of periosteal osteosarcoma: radiologic-pathologic comparison

PURPOSE

To review the imaging appearance of periosteal osteosarcoma, with pathologic comparison.

MATERIALS AND METHODS

Data for 40 pathologically confirmed periosteal osteosarcomas were retrospectively reviewed. Patient demographic data were recorded, and radiographs (n = 40), bone scintigrams (n = 10), angiograms (n = 2), and computed tomographic (CT) (n = 11) and magnetic resonance (MR) (n = 12) images were evaluated for lesion location and size, cortical changes, marrow involvement, and intrinsic characteristics by two musculoskeletal radiologists, with agreement by consensus. Pathology reports were reviewed for presence and predominance of histologic components (fibrous, chondroid, and osteoid), tumor grade, and marrow involvement.

RESULTS

There were 25 male (62%) and 15 female (38%) patients with an age range of 10-37 years (average age, 20 years). The most frequent lesion locations were the diaphysis of the tibia (16 patients) or of the femur (15 patients). Radiographs showed a broad-based soft-tissue mass that was attached to the cortex (all patients) and showed cortical thickening (33 patients), cortical scalloping/erosion (37 patients), and/or perpendicular periosteal reaction (38 patients) extending into the soft-tissue mass. Soft-tissue masses were well defined in 91%-100% of cases and surrounded a median of 50%-55% of the cortex. Lesions commonly showed low attenuation at CT (10 patients) and high signal intensity on T2-weighted MR images (10 patients), reflecting the high water content of these largely chondroblastic lesions. Focal areas of adjacent marrow replacement were common at MR imaging (nine patients) but represented reactive changes unless they were in direct continuity with the overlying soft-tissue mass (this was rare, occurring in only one patient, and represented marrow invasion). Review of pathology reports revealed that all lesions contained chondroid tissue, which predominated in 34 patients.

CONCLUSION

The radiologic appearance of periosteal osteosarcoma is a broad-based surface soft-tissue mass causing extrinsic erosion of thickened underlying diaphyseal cortex and perpendicular periosteal reaction extending into the soft-tissue component. Reactive marrow changes are commonly seen at MR imaging, but true marrow invasion is rare.

Imaging of malignant tumours of the long bones in children: monitoring response to neoadjuvant chemotherapy and preoperative assessment

This review focuses on imaging of osteosarcoma and Ewing's sarcoma of the long bones in children during preoperative neoadjuvant chemotherapy. Morphological criteria on plain films and conventional static MRI are insufficiently correlated with histological response. We review the contribution of dynamic MRI, diffusion-weighted MR and nuclear medicine (18FDG-PET) to monitor tumoural necrosis. MRI is currently the best method to evaluate local extension prior to tumour resection, especially to assess the feasibility of conservative surgery. Quantitative models in dynamic MRI and 18FDG-PET are currently being developed in order to find new early prognostic criteria, but for the time being, treatment protocols are still based on the gold standard of histological response.

Limb sparing surgery for pediatric musculoskeletal tumors

There has been an unprecedented improvement in the survival outcome of children with extremity sarcoma as well as a corresponding increase in percentage of limb-sparing surgeries being performed over the past many decades. This has been, in part, due to the improved imaging modalities, newer surgical techniques, and advences in neoadjuvant chemotherapy. Limb-sparing surgery for primary bone and soft-tissue malignancies in children is becoming an acceptable option of surgical treatment in most cases today. This article outlines the demographics, classification, clinical presentation, imaging, and molecular genetics of pediatric mosculoskeletal tumors and discusses the current treatment principles with emphasis on the state-of-the-art surgical management and limb-sparing techniques for children with extremity sarcoma.

Accuracy of magnetic resonance imaging for estimating intramedullary osteosarcoma extent in pre-operative planning of canine limb-salvage procedures

The objective of this work was to compare the accuracy of radiographs and magnetic resonance imaging (MRI) for estimating appendicular osteosarcoma margins. The accuracy of computed tomography (CT) and bone scintigraphy was also assessed when these studies were available. Eight dogs with appendicular osteosarcoma underwent radiographic and MRI of affected limbs. In addition, bone scintigraphy was performed in six dogs and CT examination was performed in five dogs. Two observers jointly measured tumor length on all imaging studies. Correlative gross and histologic evaluation of all affected limbs was performed to determine tumor extent as measured from the nearest articular surface. Results from imaging studies were compared to gross and microscopic morphometry findings to determine the accuracy of each modality for determining tumor boundaries. MRI images were accurate with a mean overestimation of actual tumor length of 3 +/- 13%. T1-weighted non-contrast images were superior in identifying intramedullary tumor margins in most instances whereas contrast-enhanced images provided supplemental information in two dogs. Lateromedial and craniocaudal radiographs overestimated tumor length by 17 +/- 28% and 4 +/- 26%, respectively. Scintigraphy and CT overestimated tumor margins by 14 +/- 28% and 27 +/- 36%, respectively. MRI appears to be an accurate diagnostic imaging modality in determining intramedullary osteosarcoma boundaries. MRI should be considered as part of a pre-operative assessment of appendicular osteosarcoma, particularly when a limb-sparing procedure is contemplated.

Primary bone tumors of the lower extremities

The key to adequate and accurate evaluation, diagnosis, and treatment of bone tumors is an organized and integrated approach involving the surgeon, radiologist, and pathologist. The radiologist plays not only a valuable role in the diagnosis and preoperative staging of bone tumors but may also play a role in biopsy and treatment. Despite the wide variety of imaging modalities available today, radiographs remain the mainstay in the evaluation of osseous neoplasms. Advanced imaging is. however. very useful for staging purposes and for characterization of the internal characteristics of tumors and may aid significantly in limiting the differential diagnosis. Although a detailed discussion of all ofthe various bone tumors of the lower extremities is beyond the scope of this article, an attempt is made to provide a framework for a rational and comprehensive approach to these complicated but relatively uncommon lesions. Certain lesions with unique characteristics are discussed to facilitate the diagnostic process.

Accuracy of radiography, nuclear scintigraphy, and histopathology for determining the proximal extent of distal radius osteosarcoma in dogs

OBJECTIVE

To compare the accuracy of radiography, nuclear scintigraphy, and histopathology for determining the proximal extent of distal radius osteosarcoma in dogs.

STUDY DESIGN

Retrospective clinical study.

SAMPLE POPULATION

Twenty client-owned dogs taken to Colorado State University with osteosarcoma of the distal radius.

METHODS

Medical records of 20 dogs with confirmed osteosarcoma that underwent a limb-salvage procedure were reviewed. Measurements were performed directly from the lateral view of each radius, from both the scintigram and the radiograph, to determine the length of the radius and the distance from the proximal extent of the tumor to the distal radiographic or scintographic extent of the radius. The ratio of distal radial involvement to total radius length was calculated. A similar ratio was also determined using the macroslide, which included the entire portion of bone that was excised during the limb-salvage procedure. All 3 methods of measurement were compared.

RESULTS

Nuclear scintigraphy significantly overestimated tumor length when compared with macroslide specimen measurements. Radiography also overestimated tumor length, but these results were not significantly different from macroslide specimen measurements.

CONCLUSIONS

Both radiography and nuclear scintigraphy overestimate the extent of distal radius osteosarcoma in dogs when compared with histopathologic macroslides of the same lesions. Nuclear scintigraphy overestimated tumor extent to a larger degree than did radiography.

CLINICAL RELEVANCE

Although radiography is a more accurate method of measurement of the extent of distal radius osteosarcoma, because nuclear scintigraphy overestimates tumor length to a greater degree, scintigraphy may provide a larger margin of safety for determining the site of proximal osteotomy during a limb-salvage procedure. However, caution should be taken when utilizing scintigraphy, because this method may overestimate length of radius involved to such an extent as to cause the surgeon to believe that a patient is not a suitable limb-salvage candidate.

[Osteogenic exostosis of the capitate bone. Case report and review of the literature]

The occurrence of an osteochondroma in the carpus is very rare and its excision is indicated in the case of significant symptoms or change in its appearance. The diagnosis is often made in adulthood due to the onset of a functional problem even though development of the tumour occurs during skeletal growth. We report the case of a 38 year old patient, with no antecedent trauma, who presents with simultaneous exostoses on the dorsal and palmar surfaces of the capitate, which has not been previously described in the literature. The existence of a bipolar lesion extending anteriorly and posteriorly in the carpus is a possibility which may not be apparent and renders plain radiograph insufficient in the investigation of such a lesion. CT scan and MRI scan are indispensable in the investigation of this kind of carpal lesions, allowing better visualization of the base of the tumour, the expansion of the tumour and relation to the neighbouring soft tissues and the presence of malignant degeneration.

Epiphyseal plate involvement in osteosarcoma

Fourteen boys (56%) and 11 girls (44%) 4 to 17 years of age (mean, 12.2 years) who had osteosarcoma and open epiphyseal plates were studied. A possible correlation between transepiphyseal spread of osteosarcoma and radiologic and histopathologic findings was investigated. Epiphyseal plate invasion was detected radiologically in only 11 patients (44%), whereas histopathologic examination showed transepiphyseal extension in 21 patients (84%). The authors conclude that the epiphyseal plate is not a barrier against tumor growth and strongly recommend that limb salvage surgery preserving the epiphysis be planned carefully.

Sarcoma and metastatic carcinoma

Primary tumors of the bone and soft tissue of the pelvis are rare. Proper surgical treatment requires a fundamental knowledge of the biology of malignant musculoskeletal neoplasms. This understanding allows stratification of sarcomas into a staging system. In addition to prognostic value, the careful staging of the neoplasms dictates the type of surgical margins necessary and guides in the use of adjuvant therapy. Limb salvage techniques developed for the reconstruction of major extremity structural deficits can be used for reconstruction of the pelvis. This review first addresses the biologic behavior and staging of malignant musculoskeletal neoplasms. The surgical techniques employed for the resection and the reconstruction of the pelvis are then discussed.

Magnetic resonance imaging of the musculoskeletal system. Part 9. Primary Tumors

Magnetic resonance imaging, because of its exquisite soft tissue contrast, has dramatically improved the ability to preoperatively stage primary osseous and soft tissue neoplasms. This technique also has allowed the monitoring of the effects of chemotherapy and the screening for recurrence of neoplasms. The role of magnetic resonance imaging in the preoperative evaluation of the patient with a suspected primary osseous or soft tissue neoplasm is outlined, instances where magnetic resonance imaging potentially may make a specific diagnosis are outlined, the importance of gadolinium enhancement as an adjunct to native magnetic resonance imaging is stressed, and an algorithm for followup of patients after chemotherapy or definitive surgical treatment is presented. In all cases, the magnetic resonance images should be correlated with the plain film, which is still an important aspect of the diagnosis of osseous lesions.

Imaging the child with a limp

A great many pathologic conditions can cause a child to limp. Prior to imaging, it is necessary to complete a thorough history and physical examination in order to limit the differential diagnosis to a few possible causes. The selection of imaging modalities should then be guided by the history and physical examination findings. Because of their sensitivity and specificity for detecting a wide range of bone pathology, radiographs should be obtained first. Plain radiographs often are diagnostic. The choice of sonography, CT, bone scintigraphy, or MR imaging is made while keeping in mind the strengths of each imaging modality.

Does magnetic resonance imaging make a difference for patients with musculoskeletal sarcoma?

MR imaging has had an unparalleled impact on the treatment of patients with musculoskeletal sarcoma. Basically, the high accuracy of local staging has made the introduction of reconstructive and limb salvage procedures instead of amputation of disarticulation available to the majority of patients with musculoskeletal sarcoma. Pre-operative work-up with MRI is not only more accurate, but also much faster and cheaper than the conventional work-up. Staging is the single most important reason for performing MR imaging in patients with musculoskeletal tumours. The impact of MR specificity is less dramatic but the benefit to the patient is an increased safety margin. When diagnostic errors with devastating consequences are made nowadays, it is usually because the proper protocol has not been followed. A patient with a potentially malignant, or equivocal, musculoskeletal mass deserves to have a combined radiographic-MRI examination prior to invasive procedures. MRI does not currently have a major impact on chemotherapy decisions and colour Doppler ultrasound has a higher accuracy than MRI. However, selected cases, i.e. intraosseous tumours, dynamic Gd-enhanced MRI, can replace colour Doppler ultrasound.