Accuracy of MR imaging for estimating intraosseous extent of osteosarcoma

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.

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

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

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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.

Determination of skeletal tumor extent: is an isotropic T1-weighted 3D sequence adequate?

OBJECTIVES

To test the hypothesis that an accelerated, T1-weighted 3D CAIPIRINHA SPACE sequence with isotropic voxel size offers a similar performance to conventional T1-weighted 2D TSE (turbo spin echo) for the evaluation of bone tumor extent and characteristics.

METHODS

Thirty-four patients who underwent 3-T MRI with 3DT1 (CAIPIRINHA SPACE TSE) and 2DT1 (TSE) were included. Sequence acquisition time was reported. Two radiologists independently evaluated each technique for tumor location, size/length, tumor-to-joint distance, signal intensity, margin/extraosseous extension, and signal-to-noise (SNR) and contrast-to-noise (CNR) ratios.

RESULTS

Tumors were located in long (20/36, 55.5%) and pelvic (16/36, 44.4%) bones. 3DT1 sequence required an average acquisition time of 235 s (± 42 s, range 156-372), while two plane 2DT1 sequences combined (coronal and axial) had an average acquisition time of 381 s (± 73 s, range 312-523). There was no difference in the measurements of tumor length and tumor-to-joint distance (p = 0.95) between 3DT1 and 2DT1 images. Tumors were hypointense (17/36, 47.2% vs 17/36, 47.2%), isointense (12/36, 33.3% vs 12/36, 33.3%), or hyperintense (7/36, 19.4% vs 7/36, 19.4%) on 3DT1 vs 2DT1, respectively. Assessment of tumor margins and extraosseous extension was similar, and there was no difference in tumor SNR or CNR (p > 0.05).

CONCLUSIONS

An accelerated 3D CAIPIRINHA SPACE T1 sequence provides comparable assessments of intramedullary bone tumor extent and similar tumor characteristics to conventional 2DT1 MRI. For the assessment of bone tumors, the isotropic volume acquisition and multiplanar reformation capability of the 3DT1 datasets can obviate the need for 2DT1 acquisitions in multiple planes.

KEY POINTS

• 3DT1 offers an equivalent performance to 2DT1 for the assessment of bone tumor characteristics, with faster and higher resolution capability, obviating the need for acquiring 2DT1 in multiple planes. • There was no difference in the measurements of tumor length and tumor-to-joint distance obtained on 3DT1 and 2DT1 images. • There was no difference in signal-to-noise ratio (SNR) or contrast-to-noise ratio (CNR) measures between 3DT1 and 2DT1.

Imaging Analyses of Bone Tumors

Despite the evolution in imaging, especially the introduction of advanced imaging technologies, radiographs still are the key for the initial assessment of a bone tumor. Important aspects to be considered in radiographs are the location, shape and size or volume, margins, periosteal reaction, and internal mineralization of the tumor's matrix; careful evaluation of these may provide for accurate diagnosis in >80% of cases. Computed tomography and magnetic resonance imaging are often diagnostic for lesions with typical findings such as the nidus of osteoid osteoma and bone destruction such as in Ewing sarcoma and lymphoma that may be difficult to detect with radiographs; they may also be used for surgical planning. Magnetic resonance imaging accurately determines the intraosseous extent and articular and vascular involvement by the tumor. This article summarizes the diagnostic accuracy of imaging analyses in bone tumors and emphasizes the specific radiographic findings for optimal radiographic diagnosis of the patients with these tumors.

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.

Transition from Tumor Tissue to Bone Marrow in Patients with Appendicular Osteosarcoma after Neoadjuvant Chemotherapy

Background:

Limb-salvage surgery is the standard procedure for the treatment of appendicular osteosarcoma. Precise resection is the trend in limb-salvage surgery. The aim of this study was to evaluate a large series of cases to identify the histological relationship between the tumor and marrow and determine the intramedullary transition type and width from the tumor to normal marrow in patients with osteosarcoma after neoadjuvant chemotherapy.

Methods:

One hundred and six osteosarcoma specimens were evaluated. The tissue specimens were sectioned through the coronal axis by an electronic saw. The tissue was immersed in formalin solution for fixation and subsequently decalcified. The interface between the tumor and normal bone marrow was grossly determined and submitted for microscopic evaluation to detect the relationship between the tumor and bone marrow and identify the transition type and width. All histological slides were examined by experienced orthopedic pathologists.

Results:

Histologically, the interface between the tumor and normal bone marrow was classified into two patterns: “clear” and “infiltrated.” The clear pattern, characterized by a clear boundary between the tumor and marrow, was identified in sixty cases (56.6%). A subtype of the clear type, characterized by fibrous bands between the tumor and marrow, was found in 13 cases (12.3%). The infiltrated pattern, characterized by a boundary with tumor cell clusters embedded in the marrow, was found in 46 cases (43.4%). The infiltrating depth varied from 1 to 4 mm (mean, 2.6 ± 0.7 mm). No tumor cells were observed in the normal bone marrow areas next to the interface.

Conclusions:

The transition from osteosarcoma tissue to bone marrow after neoadjuvant chemotherapy can be divided into two histological patterns: clear and infiltrated. The greatest infiltration width was 4 mm from tumor to normal marrow in this study. This depth should be considered in the presurgical plan.

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.

Resurfaced Allograft-Prosthetic Composite for Proximal Tibial Reconstruction in Children

Introduction

Reconstruction of the proximal part of the tibia in children with use of an unconstrained tibial component cemented in an allograft-prosthetic composite after proximal tibial resection spares the distal femoral physis and articular cartilage, maintains the bone stock of the tibia, and allows the allograft to be adapted to the small tibial dimension in very young patients.

Step 1 Make the Incision

Make a longitudinal incision medially or laterally, depending on the side of the biopsy (usually medial), encompassing and encircling the biopsy site.

Step 2 Perform the Arthrotomy

A parapatellar arthrotomy is performed, and the cruciate ligaments are cut close to the femoral attachment.

Step 3 Isolate the Vascular Bundle

Retract the medial gastrocnemius muscle and then isolate and protect the popliteal and posterior tibial vessels.

Step 4 Perform an Osteotomy of the Tibia

Perform an osteotomy of the tibiofibular joint and the tibial shaft at the appropriate level as determined on the basis of the preoperative imaging, and then complete the resection.

Step 5 Prepare the Allograft on a Separate Table

Cut and prepare the allograft according to the specimen dimensions.

Step 6 Prepare the Composite Device

Cement the tibial component of an unconstrained total knee prosthesis in the allograft and place the trial device.

Step 7 Fix the Composite Device and Suture the Capsule and Ligaments

Place the trial composite device and then fix the composite device to the host tibia and suture the capsule and ligaments.

Step 8 Postoperative Care

Immobilize the knee with an above-the-knee plaster cast, which is worn for six weeks, and then have the patient perform progressive functional rehabilitation.

Results

The rate of postoperative infection after proximal tibial reconstruction with a resurfaced allograft composite in children has been found to be no higher than that with other reconstructive techniques for the proximal part of the tibia; our series had a 5% rate of deep infection.IndicationsContraindicationsPitfalls & Challenges.

Survival, recurrence, and function after epiphyseal preservation and allograft reconstruction in osteosarcoma of the knee

BACKGROUND

Bone tumor resections for limb salvage have become the standard treatment. Recently, intercalary tumor resection with epiphyseal sparing has been used as an alternative in patients with osteosarcoma. The procedure maintains normal joint function and obviates some complications associated with osteoarticular allografts or endoprostheses; however, long-term studies analyzing oncologic outcomes are scarce, and to our knowledge, the concern that a higher local recurrence rate may be an issue has not been addressed.

QUESTIONS/PURPOSES

We wanted to assess (1) the overall survival in patients treated with this surgical technique; (2) the percentage of local recurrence and limb survival, specifically the incidence of recurrence in the remaining epiphysis; (3) the frequency of orthopaedic complications, and, (4) the functional outcomes in patients who have undergone intercalary tumor resection.

METHODS

We analyzed all 35 patients with osteosarcomas about the knee (distal femur and proximal tibia) treated at our center between 1991 and 2008 who had resection preserving the epiphysis and reconstruction with intercalary allografts. Minimum followup was 5 years, unless death occurred earlier (mean, 9 years; range, 1-16 years), and no patients were lost to followup. During the study period, our indications for this approach included patients without metastases, with clinical and imaging response to neoadjuvant chemotherapy, that a residual epiphysis of at least 1 cm thickness could be available after a surgical margin width in bone of 10 mm was planned, and 16% of patients (35 of 223) meeting these indications were treated using this approach. Using a chart review, we ascertained overall survival of patients, oncologic complications such as local recurrence and tumor progression, limb survival, and orthopaedic complications including infection, fracture, and nonunion. Survival rates were estimated using the Kaplan-Meier method. Patient function was evaluated using the Musculoskeletal Tumor Society (MSTS)-93 scoring system.

RESULTS

Overall survival rate of the patients was 86% (95% CI, 73%-99%) at 5 and 10 years. Five patients died of disease. No patient had a local recurrence in the remaining bony epiphysis, but three patients (9%; 95% CI, 0%-19%) had local recurrence in the soft tissue. The limb survival rate was 97% (95% CI, 89%-100%) at 5 and 10 years. Complications treated with additional surgical procedures were recorded for 19 patients (54%), including three local recurrences, two infections, 11 fractures, and three nonunions. In 10 of these 19 patients, the allograft was removed. Only five of the total 35 study patients (14%) lost the originally preserved epiphysis owing to complications. The mean functional score was 26 points (range, 10-30 points, with a higher score representing a better result) at final followup.

CONCLUSIONS

Although the recurrence rate was high in this series, the small sample size means that even one or two fewer recurrences might have resulted in a much more favorable percentage. Because of this, future, larger studies will need to determine whether this is a safe approach, and perhaps should compare epiphyseal preservation with other possible approaches, including endoprosthetic reconstruction and/or osteoarticular allografts.

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.

[Benign bone tumors and tumor-like lesions. What must clinicians know about imaging?]

PURPOSE

Benign bone tumors are relatively seldom compared to degenerative and inflammatory skeletal diseases. There are usually diagnostic difficulties because of their markedly high differential diagnostic potential. This leads to problems regarding the further procedure.

PROBLEM

Evaluation of the significance of radiology in the management of benign skeletal lesions.

MATERIAL AND METHODS

Significant diagnostic elements of benign bone tumors are presented by means of data from the well-known literature and personal experiences.

RESULTS

The tasks in radiology when diagnosing primary bone tumors or tumor-like lesions are firstly, detection or exclusion of a lesion, secondly, limiting the differential diagnostic possibilities or reaching a certain diagnosis and thirdly, staging of bone tumors in cases where the disease needs further diagnostic measures. In particular circumstances the diagnostics of disease recurrence can additionally be necessary.

CONCLUSION

The diagnostics of primary and secondary benign (and malignant) bone tumors requires a specialized osteoradiological expertise because of their rarity and the differential diagnostic and differential therapeutic potential. Radiology and pathology are the basis of diagnosing bone tumors and tumor-like lesions. Benign bone tumors and tumor-like lesions can often be diagnosed radiologically; therefore, the choice between a conservative (surveillance) or interventional (surgery) procedure will be correct in most cases.

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.

Is [F-18]-fluorodeoxy-D-glucose positron emission tomography of value in the management of patients with craniofacial bone sarcomas undergoing neo-adjuvant treatment?

Background

We evaluated the role of ¹⁸FDG PET/CT used to assess response to preoperative chemotherapy in patients with primary craniofacial bone sarcomas.

Methods

Fourteen patients with craniofacial bone sarcomas (13 osteosarcoma, 1 spindle cell sarcoma) were retrospectively evaluated. All patients received up to 6 cycles of preoperative chemotherapy followed by resection of the primary tumour. Response to treatment was assessed using MRI (RECIST criteria) and ¹⁸FDG PET/CT (EORTC guidelines), performed at least at baseline, after 2-4 cycles and pre-operatively.

Results

The median baseline ¹⁸FDG PET/CT SUV was 10.2 (range 0-41); in 2 patients no uptake was detected. The preoperative ¹⁸FDG PET/CT, compared with the baseline, demonstrated a partial metabolic response in 7 patients (59%), complete metabolic response in 2 (16%) and stable metabolic disease in 3 (25%). In contrast, only two patients achieved a RECIST response on MRI: 10 (83%) had stable disease. One patient underwent early resection due to clinical progression after an initial response to treatment. This was confirmed by PET (SUV from 21 to 42) but not on MRI. Twelve of 14 patients (86%) had <90% histological necrosis in the resected tumour. At a median follow-up 23 months, 11 patients (79%) remain disease free, two had metastatic progression (14%) and 1 a local relapse (7%). The median DFS was 17 months. For those patients who achieved a response to preoperative ¹⁸FDG PET/CT the median DFS was 19 months (range: 1-66) compared with 3 months (range: 3-13) in those who did not (p = 0.01). In contrast, the median disease free survival (DFS) did not differ according to histological response (19 versus 17 months, >90% versus <90% necrosis, p = 0.45) or resection margins (19 months for R0 versus 18 months for R1, p = 0.2).

Conclusion

¹⁸FDG PET/CT is more reliable than standard imaging in evaluating response to neo-adjuvant chemotherapy in craniofacial bone sarcomas, changed management in one patient, and in this small series, correlated better with patient outcome than histological response and resection margins. These results warrant prospective validation in a larger cohort of patients.

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.

Haptic robot-assisted surgery improves accuracy of wide resection of bone tumors: a pilot study

BACKGROUND

Accurate reproduction of the preoperative plan at the time of surgery is critical for wide resection of primary bone tumors. Robotic technology can potentially help the surgeon reproduce a given preoperative plan, but yielding control of cutting instruments to a robot introduces potentially serious complications. We developed a novel passive ("haptics") robot-assisted resection technique for primary bone sarcomas that takes advantage of robotic accuracy while still leaving control of the cutting instrument in the hands of the surgeon.

QUESTIONS/PURPOSES

We asked whether this technique would enable a preoperative resection plan to be reproduced more accurately than a standard manual technique.

METHODS

A joint-sparing hemimetaphyseal resection was precisely outlined on the three-dimensionally reconstructed image of a representative Sawbones femur. The indicated resection was performed on 12 Sawbones specimens using the standard manual technique on six specimens and the haptic robotic technique on six specimens. Postresection images were quantitatively analyzed to determine the accuracy of the resections compared to the preoperative plan, which included measuring the maximum linear deviation of the cuts from the preoperative plan and the angular deviation of the resection planes from the target planes.

RESULTS

Compared with the manual technique, the robotic technique resulted in a mean improvement of 7.8 mm of maximum linear deviation from the preoperative plan and 7.9° improvement in pitch and 4.6° improvement in roll for the angular deviation from the target planes.

CONCLUSIONS

The haptic robot-assisted technique improved the accuracy of simulated wide resections of bone tumors compared with manual techniques.

CLINICAL RELEVANCE

Haptic robot-assisted technology has the potential to enhance primary bone tumor resection. Further bench and clinical studies, including comparisons with recently introduced computer navigation technology, are warranted.

Correlation between MRI appearances and serum alkaline phosphatase levels in Osteogenic sarcoma

INTRODUCTION

Magnetic resonance imaging is a pictorial depiction of the patho-anatomy of a bony lesion. As different parts of the tumor in Osteogenic sarcoma concurrently undergo various biological processes i.e. osteoblastic new bone formation, cell death, necrosis, bony destruction and revascularization etc., we hypothesized that the image seen in MRI could be used to assess the tumor behavior at that time. This study was done as a preliminary study with the aim to find whether the MRI pictures can have identifiable patterns and if present whether they can be linked to biological behavior. We could identify 2 distinct patterns in T2 weighted images which correlated well with serum alkaline phosphatase a serum marker and the duration of symptoms and so we are reporting our observations.

MATERIAL AND METHOD

T2 weighted MRI pictures of 15 cases of Osteogenic sarcoma were studied for identifiable patterns in matrix. These patterns if found were to be linked to biological behavior in the form of serum alkaline phosphatase levels and duration of symptoms.

RESULTS

We could identify 2 unique patterns named by us as Group 1 Heterogeneous type (4 cases) which had a raised serum alkaline phosphatase level and had a history at presentation of less than 3 months duration. In Group 2 homogenous type (5 cases) the serum alkaline phosphatase levels were low and the cases presented after 6 months. As we could not identify any logical pattern in rest of the cases we labeled them as miscellaneous.

DISCUSSION

MRI patterns can be used as markers of disease activity as there are 2 clear poles correlating well with serum alkaline phosphatase levels (high or low). Intermediate patterns may be the natural biological behavior and waxing and waning of the tumor disease activity.

Correlation of non-mass-like abnormal MR signal intensity with pathological findings surrounding pediatric osteosarcoma and Ewing's sarcoma

OBJECTIVE

The aim of this work was to determine the role of MRI in interpreting abnormal signals within bones and soft tissues adjacent to tumor bulk of osteosarcoma and Ewing's sarcoma in a pediatric population by correlating MR findings with histopathology.

MATERIALS AND METHODS

Thirty patients met the inclusion criteria, which included (1) osteosarcoma or Ewing's sarcoma, (2) MR studies no more than 2 months prior to surgery, (3) presence of abnormal MR signal surrounding the tumor bulk, (4) pathological material from resected tumor. The patients received standard neoadjuvant chemotherapy. Using grid maps on gross pathology specimens, the abnormal MR areas around the tumor were matched with the corresponding grid sections. Histopathology slides of these sections were then analyzed to determine the nature of the regions of interest. The MR/pathological correlation was evaluated using Mann-Whitney U test and Fisher's exact test.

RESULTS

Twenty-seven patients had osteosarcoma and three patients had Ewing's sarcoma. Of the studied areas, 17.4% were positive for tumor (viable or necrotic). There was no statistically significant correlation between areas positive for tumor and age, gender, signal extent and intensity on MRI, or tissue type. There was, however, a statistically significant correlation between presence of tumor and the appearance of abnormal soft tissue signals. A feathery appearance correlated with tumor-negative areas whereas a bulky appearance correlated with tumor-positive regions.

CONCLUSIONS

MR imaging is helpful in identifying the nature of abnormal signal areas surrounding bone sarcomas that are more likely to be tumor-free, particularly when the signal in the soft tissues surrounding the tumor is feathery and edema-like in appearance.

The results of total humeral replacement following excision for primary bone tumour

Rarely, the extent of a malignant bone tumour may necessitate resection of the complete humerus to achieve adequate oncological clearance. We present our experience with reconstruction in such cases using a total humeral endoprosthesis (THER) in 20 patients (12 male and eight female) with a mean age of 22 years (6 to 59). We assessed the complications, the oncological and functional outcomes and implant survival. Surgery was performed between June 2001 and October 2009. The diagnosis included osteosarcoma in nine, Ewing's sarcoma in eight and chondrosarcoma in three. One patient was lost to follow-up. The mean follow-up was 41 months (10 to 120) for all patients and 56 months (25 to 120) in survivors. There were five local recurrences (26.3%) and 11 patients were alive at time of last follow-up, with overall survival for all patients being 52% (95% confidence interval (CI) 23.8 to 74) at five years. The mean Musculoskeletal Tumor Society score for the survivors was 22 (73%; 16 to 23). The implant survival was 95% (95% CI 69.5 to 99.3) at five years. The use of a THER in the treatment of malignant tumours of bone is oncologically safe; it gives consistent and predictable results with low rates of complication.

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.

Imaging pediatric bone sarcomas

Primary malignant bone tumors are rare and account for about 6% of all new pediatric cancer cases per year in the United States. Identification of the lesion not uncommonly occurs as a result of imaging performed for trauma. Clinical and standard imaging characteristics of the various tumor types are evolving in concert with treatment advancements and clinical trial regimens. This article reviews the 3 most common pediatric bone sarcomas-osteosarcoma, Ewing sarcoma, and chondrosarcoma-and their imaging as applicable to contemporary disease staging and monitoring, and explores the roles of evolving imaging techniques.

How can survival be improved in localized osteosarcoma?

Despite numerous chemotherapy trials and the introduction of novel agents, survival in localized osteosarcoma, which plateaued in the mid-1980s, has been recalcitrant to our best efforts. The authors considered that a review of previous and current strategies that target survival might provide a direction for research efforts. Here, the focus is placed mainly on the reappraisal of previous mass chemotherapy trials and prognostic factors, in the hope of contriving a strategy to overcome the current stasis.

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.

Ressonância magnética na avaliação das reações periosteais

O objetivo deste ensaio iconográfico é estimular a avaliação cuidadosa das reações periosteais nas imagens de ressonância magnética. A abordagem inicial das lesões ósseas é realizada por meio das radiografias simples e pela avaliação destas se faz a classificação das reações periosteais em subtipos clássicos. Embora a ressonância magnética seja considerada o padrão ouro para o estadiamento regional das neoplasias ósseas, seu uso no estudo das reações periosteais relacionadas às lesões ósseas focais tem sido relativamente pouco enfatizado. A revisão da literatura evidencia um modelo experimental animal de osteomielite que sugere que a ressonância magnética seja superior às outras técnicas de imagem na identificação precoce das reações periosteais. Outro estudo encontrado na literatura sugere boa correlação entre as radiografias simples e as imagens de ressonância magnética na identificação e na classificação das reações periosteais no osteossarcoma. Neste ensaio foram ilustrados casos de reações periosteais observadas pela ressonância magnética, correlacionado-as com as radiografias convencionais ou com outros métodos de diagnóstico por imagem.

Assessment of histological response of paediatric bone sarcomas using FDG PET in comparison to morphological volume measurement and standardized MRI parameters

PURPOSE

The objective of this study was to evaluate positron emission tomography (PET) using (18)F-fluoro-2-deoxy-D-glucose (FDG) in comparison to volumetry and standardized magnetic resonance imaging (MRI) parameters for the assessment of histological response in paediatric bone sarcoma patients.

METHODS

FDG PET and local MRI were performed in 27 paediatric sarcoma patients [Ewing sarcoma family of tumours (EWS), n = 16; osteosarcoma (OS), n = 11] prior to and after neoadjuvant chemotherapy before local tumour resection. Several parameters for assessment of response of the primary tumour to therapy by FDG PET and MRI were evaluated and compared with histopathological regression of the resected tumour as defined by Salzer-Kuntschik.

RESULTS

FDG PET significantly discriminated responders from non-responders using the standardized uptake value (SUV) reduction and the absolute post-therapeutic SUV (SUV2) in the entire patient population (SUV, p = 0.005; SUV2, p = 0.011) as well as in the subgroup of OS patients (SUV, p = 0.009; SUV2, p = 0.028), but not in the EWS subgroup. The volume reduction measured by MRI/CT did not significantly discriminate responders from non-responders either in the entire population (p = 0.170) or in both subgroups (EWS, p = 0.950; OS, p = 1.000). The other MRI parameters alone or in combination were unreliable and did not improve the results. Comparing diagnostic parameters of FDG PET and local MRI, metabolic imaging showed high superiority in the subgroup of OS patients, while similar results were observed in the population of EWS.

CONCLUSION

FDG PET appears to be a useful tool for non-invasive response assessment in the group of OS patients and is superior to MRI. In EWS patients, however, neither FDG PET nor volumetry or standardized MRI criteria enabled a reliable response assessment to be made after neoadjuvant treatment.

Growth patterns of osteosarcoma predict patient survival

INTRODUCTION

In this retrospective study, we assessed tumor growth patterns as visualized on MR images, and examined whether tumor growth patterns correlate with clinicopathologic variables. In addition, we also evaluated the relationship between patient outcome and tumor growth pattern in the whole study cohort and in subsets of AJCC IIA and IIB patients.

MATERIALS AND METHODS

We retrospectively reviewed 347 patients with Enneking stage IIB and AJCC stage II osteosarcoma that was treated with surgery and neoadjuvant chemotherapy at our institute. Patients were divided into three groups based on tumor growth pattern, namely, concentric, eccentric, and longitudinal groups. Fisher's exact test was performed to analyze correlations between tumor growth patterns and clinicopathological variables. Five-year metastasis-free survival and overall survival were evaluated using univariate and multivariate analyses.

RESULTS

In terms of tumor growth patterns, 225 patients (64.8%) had a concentric, 71 (20.5%) an eccentric and 51 (14.7%) a longitudinal tumor. Eccentric tumors were usually small and responded well to chemotherapy, whereas concentric tumors were large and responded poorly. The prognostic significances of tumor growth patterns were confirmed by univariate and multivariate analyses. Among AJCC stage IIA patients, no survival difference was found according to growth pattern, whereas in AJCC stage IIB patients, longitudinal tumors were associated with significantly better survival than concentric tumors.

CONCLUSIONS

Tumor growth pattern was found to be an independent prognostic factor in stage II osteosarcoma. Moreover, longitudinally growing tumors were associated with better survival in AJCC stage IIB patients. Our results suggest that tumor growth pattern could be used as an indicator of risk-adapted therapy when combined with other prognostic factors.

Effect of increases in tumor volume after neoadjuvant chemotherapy on the outcome of stage II osteosarcoma regardless of histological response

BACKGROUND

We assessed volume changes after neoadjuvant chemotherapy and evaluated relations between tumor size changes and clinical characteristics. In addition, we sought to determine whether tumor size change influences patient outcome.

METHODS

The records of 127 patients with stage II osteosarcoma who showed more than a 15% volume change after chemotherapy were retrospectively reviewed. Patients were divided into two groups depending on whether tumors increased or decreased in size. Fisher's exact test was performed to analyze correlations between tumor size changes and clinicopathological variables. Five-year metastasis-free survival and overall survival were evaluated using univariate and multivariate analyses.

RESULTS

A total of 71 patients (55.9%) showed a decrease in tumor volume, and 56 patients (44.1%) showed an increase. An increase in tumor volume after neoadjuvant chemotherapy was found to be positively correlated with a poor histological response and subsequent metastasis. Univariate analysis identified the following parameters as poor prognostic factors: age < or = 15 years (P = 0.03), American Joint Committee on Cancer (AJCC) stage IIB (P = 0.02), a subtype other than osteoblastic (P < 0.01), a poor histological response (P < 0.001), and increased tumor volume after preoperative chemotherapy (P < 0.0001). Multivariate analysis revealed that AJCC stage IIB (P = 0.006) and an increase in tumor volume after preoperative chemotherapy (P < 0.001) both independently shortened metastasis-free survival. However, a poor histological response lost its prognostic significance (P = 0.34).

CONCLUSIONS

Increased tumor volume after neoadjuvant chemotherapy independently shortened metastasis-free and overall survival in AJCC stage II osteosarcoma patients. Tumor volume changes may serve as a basis for risk-adapted therapy when used in combination with other prognostic factors.

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.

Epiphyseal preservation and an intercalary vascularized fibular graft with hydroxyapatite composites. Reconstruction in metaphyseal osteosarcoma of the proximal tibia: a case report

BACKGROUND DATA AND OBJECTIVES: We present here a case report of a patient with metaphyseal osteosarcoma with a preserved epiphysis and reconstructed by a vascularized fibular graft and hydroxyapatite composites.

METHODS

The case was a 14-year-old boy, who had osteosarcoma in the proximal tibia. After the diagnosis was confirmed by biopsy, the patient immediately received preoperative chemotherapy including high-dose Methotrexate, Cisplatin and Doxrubicin. Imagings after preoperative chemotherapy including MRI and contrasted enhanced CT confirmed no tumor penetration into the physis. Subsequently, we performed transepiphyseal resection of the proximal tibia to reserve the joint surface. The intercalary twin-barreled vascularized fibular graft was placed with hydroxyapatite composites. The patella tendon was reattached to the grafted fibular to biologically reconstruct the knee extensor mechanism. Postoperative chemotherapy was completed with the same regime as preoperative chemotherapy.

OUTCOMES

The bony union was completed at 10 months after the operation. The Enneking's functional evaluation score was 28 out of 30 points (93%). There was no evidence of local recurrence and no metastatic disease during the 42 months follow-up after initial diagnosis.

CONCLUSION

An accurate evaluation of MRI and CT can give a reliable assessment of intraphyseal penetration of metaphyseal osteosarcoma. In case of no involvement of the tumor in the physis, transepiphyseal osteotomy is the optimal procedure to preserve the joint surface and superior function of the joint, especially in the proximal tibia.

Tumor necrosis rate adjusted by tumor volume change is a better predictor of survival of localized osteosarcoma patients

BACKGROUND

We assessed whether new parameter that considers both tumor volume change and necrosis rate predicts metastasis-free survival of localized osteosarcoma patients. We also evaluated relationship between tumor volume change and necrosis rate or metastasis-free survival.

METHODS

We retrospectively reviewed 151 patients with stage II osteosarcoma who were treated with surgery and neoadjuvant chemotherapy. The tumor volume change was measured and calculated based on pre- and postchemotherapy magnetic resonance images. The mean metastasis-free interval was 83.1 months. We calculated adjusted tumor necrosis rate as following formula: 100 - (100 - necrosis rate) x postchemotherapy/prechemotherapy tumor volume. Survival and logistic regression analyses were used to evaluate the correlation among size parameters, tumor necrosis rate and survival.

RESULTS

The 5-year metastasis-free survival rate of 151 patients was 71.4% (95% CI, 67.7-75.1%). American Joint Committee on Cancer (AJCC) stage IIB (RR 2.27; 95% CI, 1.11-4.62; P = 0.025) and poor adjusted tumor necrosis rate (RR 2.02; 95% CI, 1.05-3.89; P = 0.035) independently correlated with metastasis-free survival period. Further, tumor volume change independently correlated with necrosis rate. Decreased tumor volume could predict good response, with sensitivity of 80.2%, specificity of 68.6%, and positive predictive value (PPV) of 74.7%. Increased or stable tumor volume could predict poor response, with sensitivity of 68.6%, specificity of 80.2%, and PPV of 75.0 %.

CONCLUSION

The necrosis rate adjusted by the tumor volume change is an independent prognostic factor in osteosarcoma. This adjusted tumor necrosis rate may serve as a basis for risk-adapted therapy in combination with other prognostic factors.

Partial epiphyseal preservation and intercalary allograft reconstruction in high-grade metaphyseal osteosarcoma of the knee

BACKGROUND

The purpose of this study was to analyze a series of patients with a high-grade metaphyseal osteosarcoma of the knee who had been treated with a transepiphyseal resection, with preservation of the distal femoral and the proximal tibial (articular) portions of the epiphysis, and an intercalary allograft reconstruction.

METHODS

The cases of thirteen patients with a high-grade metaphyseal osteosarcoma around the knee who had transepiphyseal resection and reconstruction with an intercalary allograft were retrospectively reviewed at a mean of sixty-three months. Complications, disease-free survival of the patient, final preservation of the limb and epiphysis, and functional results according to the Musculoskeletal Tumor Society scoring system were documented at the time of the latest follow-up.

RESULTS

At the final follow-up examination, eleven of the thirteen patients continued to be disease-free. One patient died of bone and pulmonary metastases with no evidence of local recurrence, and the remaining patient had no evidence of disease after resection of a local recurrence of the tumor in the soft tissues. No patient had a local recurrence in the remaining epiphysis. Seven patients had complications that included a fracture (three patients), diaphyseal nonunion (two), deep infection (one), and a local recurrence in the soft tissues (one). The allograft was removed in only four of these patients. At the latest follow-up examination, twelve patients were alive with preserved limbs. In one patient, the epiphysis, which originally had been preserved, was resected because of a metaphyseal fracture, and the limb was reconstructed with an osteoarticular allograft. The patients with a preserved epiphysis had an average functional score of 27 points (maximum, 30 points).

CONCLUSIONS

Preservation of the epiphysis in high-grade metaphyseal osteosarcoma at the knee is an alternative in carefully selected patients. Crucial factors needed to obtain local tumor control and achieve an acceptable functional result are a positive response to chemotherapy, accurate preoperative assessment of tumor extension to the epiphysis, and appropriate fixation techniques for intercalary allografts.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

Tumor size as a predictor of outcome in pediatric non-metastatic osteosarcoma of the extremity

BACKGROUND

Better predictors of outcome would allow improved risk-adapted therapy for pediatric nonmetastatic osteosarcoma of the extremity. We investigated the predictive value of MR imaging-based measures of absolute and relative tumor size and volume at the time of diagnosis. We also assessed the relation of tumor size to age and histologic response.

METHODS

We retrospectively abstracted demographic, treatment history, and outcome information of patients treated on a single institutional protocol. A single pediatric oncologic radiologist manually measured each primary lesion and the affected native bone in three dimensions on MR images obtained at the time of diagnosis. Eight parameters of tumor size were analyzed for their value in predicting overall survival (OS) and event-free survival (EFS).

RESULTS

The median age of the 42 patients was 13.5 years (range: 5.9-18.7 years); 50% were female and 74% were Caucasian. Absolute tumor volume was an important predictor of OS (P < 0.05); absolute tumor depth (analyzed as a continuous variable) was a significant predictor of OS (P = 0.018) and EFS (P = 0.036). Relative measures of tumor size were not found to predict outcome. No relation was seen between tumor size and histologic response.

CONCLUSIONS

Absolute tumor size at the time of diagnosis is significantly predictive of OS and EFS. If validated in a larger study, this indicator should be used in the design of risk-adapted treatment protocols for osteosarcoma.

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.

Comparison of whole-body STIR-MRI and 99mTc-methylene-diphosphonate scintigraphy in children with suspected multifocal bone lesions

The study was performed to compare whole-body short time inversion recovery (STIR) MR imaging and (99m)Tc-methylene diphosphonate planar scintigraphy in the examination of children with suspected multifocal skeletal malignant lesions. Sixteen patients with known or suspected malignant skeletal disease underwent both whole-body STIR MR imaging and bone scintigraphy. The lesions were described and numbered according to scintigraphic evaluation criteria. Thus, 16 regions were analyzed in each patient for the comparison between the two modalities. Histology was proven in the primary malignant regions. Follow-up MRIs were registered. Scintigraphy and MRI follow-up were evaluated as gold standard. A total of 139 different lesions was observed by both modalities. Baseline whole-body MRI revealed 119 bone lesions in 256 possible sites (46.5%); scintigraphy revealed only 58 lesions (22.6%). Congruence was observed in only four patients (25%). According to the location of the lesion, correlation was observed in 39/139 lesions (28%). In all, 57.5% of the lesions were detected only by MRI and 14.5% of the lesions were detected only by scintigraphy. Whole-body MRI was more sensitive (P<0.001). Of all lesions numbered which could be separated in the initial MRI, whole-body MRI detected 178 lesions in the patients. The results suggest that whole-body MRI using a STIR sequence is an effective radiation free method for examination of children with suspected multifocal bone lesions. MRI showed more lesions than conventional (99m)Tc-methylene diphosphonate scintigraphy. Therefore, whole-body MRI may be feasible as a screening modality for metastatic and skip lesions in osteosarcoma, PNET, Ewing sarcoma and Langerhans cell histiocytosis in children.

Whole-body magnetic resonance imaging: a useful additional sequence in paediatric imaging

BACKGROUND

Whole-body MR (WBMR) imaging allows the acquisition of images of the entire body in a matter of minutes. Its use has primarily been in the evaluation of possible metastases in the setting of a known primary tumour.

OBJECTIVE

To document the value of WBMR imaging in ten children in whom this was added as an additional sequence when the primary diagnosis had not yet been made.

MATERIALS AND METHODS

Ten children, age range 4 months-15 years (mean 7 years 4 months) had WBMR imaging after initial MR showed an abnormality that raised the possibility of systemic disease. Initial scanning was of the brain (n=1), spine (n=2), retroperitoneum (n=4), hips (n=1), femur (n=1) and wrist (n=1).

RESULTS

Abnormalities were detected in eight patients. Two patients had acute lymphoblastic leukaemia, and another had an anaplastic lymphoma, unsuspected prior to the WBMR. Two patients had a previously undiagnosed neuroblastoma with bone marrow metastases. Two patients had Langerhans' cell histiocytosis. Another had multiple bone lesions due to cystic angiomatosis.

CONCLUSIONS

WBMR imaging may be a useful additional sequence in children in whom a systemic and especially a bone marrow abnormality is suspected.

The role of imaging in the staging and treatment planning of primary malignant bone tumors in children

The accurate staging of primary bone tumors in children is critical for treatment planning. Limb salvage operations can now be performed with excellent outcomes in suitable patients. The purpose of this article is to review the current state of imaging techniques and their roles in enabling accurate staging and treatment planning to be performed in pediatric patients with primary bone tumors.

Osseous Invasion by Soft-Tissue Sarcoma: Assessment with MR Imaging

PURPOSE

To assess magnetic resonance (MR) imaging signs and overall accuracy of MR imaging for detection of osseous invasion by soft-tissue sarcoma, with histopathologic correlation as the reference standard.

MATERIALS AND METHODS

Preoperative MR images (1.5 T, transverse and longitudinal planes, T1 and T2 weighted) of 56 osseous sites in 51 patients who underwent bone resection at surgery for soft-tissue sarcoma were assessed retrospectively for signs of osseous invasion, by consensus of two readers who were blinded to clinical and histopathologic findings. Delay between MR imaging and surgery averaged 34 days (range, 2-112 days). MR signs assessed included osseous abutment by tumor, maximal diameter of osseous abutment, extent of circumferential abutment of long bones (<25%, 25%-50%, >50%), cortical destruction, and cortical and medullary signal intensity change on T1- and T2-weighted images. Imaging findings were correlated with histopathologic findings. Sensitivities, specificities, positive and negative predictive values (PPV, NPV), and P values were calculated.

RESULTS

Eleven sites (20%) showed osseous invasion histologically (two, cortical; nine, both cortical and medullary). Tumor abutted bone at 44 lesion sites (sensitivity, 100%; specificity, 27%). Maximal diameter of osseous abutment and extent of circumferential abutment did not significantly affect osseous invasion (P =.09 and.11, respectively). On T1- and T2-weighted images, 13 lesion sites showed cortical signal intensity change (sensitivity, 100%; specificity, 96%) and 10 showed cortical destruction (sensitivity, 82%; specificity, 98%). Eleven sites showed decreased medullary T1 signal intensity (sensitivity, 100%; specificity, 96%), and 12 showed increased medullary T2 signal intensity (sensitivity, 100%; specificity, 94%). MR imaging overall had a sensitivity of 100%, specificity of 93%, PPV of 79%, and NPV of 100% for detection of osseous invasion on the basis of any finding of cortical destruction or cortical or medullary signal intensity change on T1- or T2-weighted images (P <.001).

CONCLUSION

On T1- and T2-weighted MR images, findings of cortical and medullary signal intensity change and cortical destruction were sensitive and specific for detection of osseous invasion by soft-tissue 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.

Malignant and benign bone tumors

The authors have intentionally included some confusing examples to demonstrate that the imaging findings of benign and malignant pediatric bone lesions are not always pathognomonic. The radiologist's role is to recognize malignant bone lesions and encourage the prompt referral of these patients to an appropriate institution for biopsy and treatment. The radiologist must also be able to identify benign lesions and help determine whether these lesions require biopsy and intervention or simply observation.