Dynamic contrast-enhanced MR imaging for differentiation between enchondroma and chondrosarcoma

Combining morphological and functional imaging parameters to diagnose primary bone neoplasms in the skull base, spine and sacrum

PURPOSE

Morphological magnetic resonance (MR) and computed tomography (CT) features are used in combination with histology for diagnosis and treatment selection of primary bone neoplasms. Isolated functional MRI parameters have shown potential in diagnosis. Our goal is to facilitate diagnosis of primary bone neoplasms of the skull base, mobile spine and sacrum, by a comprehensive approach, combining morphological and functional imaging parameters.

MATERIALS AND METHODS

Pre-treatment MR of 80 patients with histologically proven diagnosis of a primary bone neoplasm of the skull base, mobile spine and sacrum were retrospectively analyzed for morphological and functional MRI parameters. Functional parameters were measured in 4 circular regions of interest per tumor placed on non-adjacent scan slices. Differences in values of functional parameters between different histologies were analyzed with Dunn's test.

RESULTS

Chordomas were the predominant histology (60.0%). Most neoplasms (80.0%) originated in the midline and had geographical (78.2%) bone destruction. Amorphous-type calcification (pre-existing bone) was seen only in chordomas. Homogeneous contrast enhancement pattern was seen only in chondrosarcoma and plasmacytoma. Ktrans and Kep were significantly lower in both chordoma, and chondrosarcoma compared to giant cell tumor of the bone (p = 0.006 - 0.011), and plasmacytoma (p = 0.004 - 0.014). Highest diffusion-weighted MRI apparent diffusion coefficient (ADC) values corresponded to chondrosarcoma and were significantly higher to those of chordoma (p = 0.008).

CONCLUSION

We identified the most discriminating morphological parameters and added functional MR parameters based on histopathological features that are useful in making a confident diagnosis of primary bone neoplasms in the skull base, mobile spine and sacrum.

Evaluation of the value of dynamic contrast-enhanced MRI for the diagnosis and follow-up of central cartilage tumors

OBJECTIVES

To evaluate the value of (dynamic) contrast-enhanced MRI for the diagnosis and follow-up of central cartilage tumors (CCT) of the proximal humerus, distal femur and proximal tibia.

MATERIALS & METHODS

97 patients (44 ± 11 years, 31men) with a CCT (histopathologically proven and/or > 2 years follow-up (5 ± 3 years)) were retrospectively/consecutively included at the Ghent University Hospital (Belgium, 2003-2021). Thickness of the enhancing rim and dynamic contrast-enhanced MRI parameters of the entire tumor were calculated. Tumor volumes were calculated to assess tumor growth. Significant differences between enchondromas, atypical cartilaginous tumors, high-grade chondrosarcomas, tumors with and without growth at follow-up were evaluated and ROC-curves were analyzed.

RESULTS

A significant difference (p = 0.015) existed in enhancing rim thickness between high-grade chondrosarcomas and other groups. A ROC-curve with an AUC of 0.89 and cut-off value of 1.2 mm had a sensitivity of 100 % and a specificity of 64 % to identify high-grade chondrosarcomas. A significant correlation was found between the relative maximal enhancement (Rel-Emax) of the whole tumor compared to muscle and the absolute growth rate (ρ = 0.75, p < 0.001). Lesions with a Rel-Emax < 1 remained stable or showed regression during follow-up (mean -0.1 ± 0.3 ml/year). Lesions with a Rel-Emax between 1 and 2 showed little growth (mean + 0.2 ± 0.2 ml/year), and lesions with a Rel-Emax > 2 had the highest growth rate (mean 0.4 ± 0.2 ml/year).

CONCLUSION

A thick enhancing rim > 1.2 mm has a high sensitivity to detect high-grade chondrosarcomas. The higher the Rel-Emax of the whole tumor compared to muscle, the higher the growth rate of a CCT.

A retrospective external validation study of the Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP) for the management of solitary central cartilage tumours of the proximal humerus and around the knee

OBJECTIVES

This study aimed to externally validate the Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP) recommendations for differentiation/follow-up of central cartilage tumours (CCTs) of the proximal humerus, distal femur, and proximal tibia and to propose BACTIP adaptations if the results provide new insights.

METHODS

MRIs of 123 patients (45 ± 11 years, 37 men) with an untreated CCT with MRI follow-up (n = 62) or histopathological confirmation (n = 61) were retrospectively/consecutively included and categorised following the BACTIP (2003-2020 / Ghent University Hospital/Belgium). Tumour length and endosteal scalloping differences between enchondroma, atypical cartilaginous tumour (ACT), and high-grade chondrosarcoma (CS II/III/dedifferentiated) were evaluated. ROC-curve analysis for differentiating benign from malignant CCTs and for evaluating the BACTIP was performed.

RESULTS

For lesion length and endosteal scalloping, ROC-AUCs were poor and fair-excellent, respectively, for differentiating different CCT groups (0.59-0.69 versus 0.73-0.91). The diagnostic performance of endosteal scalloping and the BACTIP was higher than that of lesion length. A 1° endosteal scalloping cut-off differentiated enchondroma from ACT + high-grade chondrosarcoma with a sensitivity of 90%, reducing the potential diagnostic delay. However, the specificity was 29%, inducing overmedicalisation (excessive follow-up). ROC-AUC of the BACTIP was poor for differentiating enchondroma from ACT (ROC-AUC = 0.69; 95%CI = 0.51-0.87; p = 0.041) and fair-good for differentiation between other CCT groups (ROC-AUC = 0.72-0.81). BACTIP recommendations were incorrect/unsafe in five ACTs and one CSII, potentially inducing diagnostic delay. Eleven enchondromas received unnecessary referrals/follow-up.

CONCLUSION

Although promising as a useful tool for management/follow-up of CCTs of the proximal humerus, distal femur, and proximal tibia, five ACTs and one chondrosarcoma grade II were discharged, potentially inducing diagnostic delay, which could be reduced by adapting BACTIP cut-off values.

CLINICAL RELEVANCE STATEMENT

Mostly, Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP) assesses central cartilage tumours of the proximal humerus and the knee correctly. Both when using the BACTIP and when adapting cut-offs, caution should be taken for the trade-off between underdiagnosis/potential diagnostic delay in chondrosarcomas and overmedicalisation in enchondromas.

KEY POINTS

• This retrospective external validation confirms the Birmingham Atypical Cartilage Tumour Imaging Protocol as a useful tool for initial assessment and follow-up recommendation of central cartilage tumours in the proximal humerus and around the knee in the majority of cases. • Using only the Birmingham Atypical Cartilage Tumour Imaging Protocol, both atypical cartilaginous tumours and high-grade chondrosarcomas (grade II, grade III, and dedifferentiated chondrosarcomas) can be misdiagnosed, excluding them from specialist referral and further follow-up, thus creating a potential risk of delayed diagnosis and worse prognosis. • Adapted cut-offs to maximise detection of atypical cartilaginous tumours and high-grade chondrosarcomas, minimise underdiagnosis and reduce potential diagnostic delay in malignant tumours but increase unnecessary referral and follow-up of benign tumours.

Application of microwave ablation assisted degradation therapy in surgical treatment of intramedullary chondrosarcoma of extremities

AIM

Clinical diagnosis and surgical treatment of chondrosarcoma (CS) are continuously improving. The purpose of our study is to evaluate the effectiveness of microwave ablation (MWA) assisted degradation therapy in the surgical treatment of intramedullary chondrosarcoma of the extremities, to provide a new reference and research basis for the surgical treatment of CS.

METHODS

We recruited 36 patients with intramedullary CS who underwent MWA assisted extended curettage. Preoperative patient demographics and clinical data were recorded. Surgery was independently assisted by a medical team. Patients were followed up strictly and evaluated for oncological prognosis, radiological results, limb joint function, pain, and complications.

RESULTS

We included 15 men and 21 women (mean age: 43.5 ± 10.1). The average length of the lesion was 8.1 ± 2.5 cm. Based on preoperative radiographic, clinical manifestations, and pathological results of puncture biopsy, 28 patients were preliminarily diagnosed with CS-grade I and eight patients with CS-grade II. No recurrence or metastasis occurred in the postoperative follow-up. The average Musculoskeletal Tumor Society score was 28.8 ± 1.0, significantly better than presurgery. Secondary shoulder periarthritis and abduction dysfunction occurred in early postoperative stage CS of the proximal humerus in some, but returned to normal after rehabilitation exercise. Secondary bursitis occurred at the knee joint in some due to the internal fixation device used in treatment; however, secondary osteoarthritis and avascular necrosis of the femoral head were not observed. Overall, oncological and functional prognoses were satisfactory.

CONCLUSIONS

The application of MWA assisted degradation therapy in intramedullary CS can achieve satisfactory oncology and functional prognosis, providing a new option for the limited treatment of CS.

Classification of Chondrosarcoma: From Characteristic to Challenging Imaging Findings

Chondrosarcomas can be classified into various forms according to the presence or absence of a precursor lesion, location, and histological subtype. The new 2020 World Health Organization (WHO) Classification of Tumors of Soft Tissue and Bone classifies chondrogenic bone tumors as benign, intermediate (locally aggressive), or malignant, and separates atypical cartilaginous tumors (ACTs) and chondrosarcoma grade 1 (CS1) as intermediate and malignant tumors. respectively. Furthermore, the classification categorizes chondrosarcomas (including ACT) into eight subtypes: central conventional (grade 1 vs. 2–3), secondary peripheral (grade 1 vs. 2–3), periosteal, dedifferentiated, mesenchymal, and clear cell chondrosarcoma. Most chondrosarcomas are the low-grade, primary central conventional type. The rarer subtypes include clear cell, mesenchymal, and dedifferentiated chondrosarcomas. Comprehensive analysis of the characteristic imaging findings can help differentiate various forms of chondrosarcomas. However, distinguishing low-grade chondrosarcomas from enchondromas or high-grade chondrosarcomas is radiologically and histopathologically challenging, even for experienced radiologists and pathologists.

Development and validation of a MRI-based combined radiomics nomogram for differentiation in chondrosarcoma

Objective

This study aims to develop and validate the performance of an unenhanced magnetic resonance imaging (MRI)-based combined radiomics nomogram for discrimination between low-grade and high-grade in chondrosarcoma.

Methods

A total of 102 patients with 44 in low-grade and 58 in high-grade chondrosarcoma were enrolled and divided into training set (n=72) and validation set (n=30) with a 7:3 ratio in this retrospective study. The demographics and unenhanced MRI imaging characteristics of the patients were evaluated to develop a clinic-radiological factors model. Radiomics features were extracted from T1-weighted (T1WI) images to construct radiomics signature and calculate radiomics score (Rad-score). According to multivariate logistic regression analysis, a combined radiomics nomogram based on MRI was constructed by integrating radiomics signature and independent clinic-radiological features. The performance of the combined radiomics nomogram was evaluated in terms of calibration, discrimination, and clinical usefulness.

Results

Using multivariate logistic regression analysis, only one clinic-radiological feature (marrow edema OR=0.29, 95% CI=0.11-0.76, P=0.012) was found to be independent predictors of differentiation in chondrosarcoma. Combined with the above clinic-radiological predictor and the radiomics signature constructed by LASSO [least absolute shrinkage and selection operator], a combined radiomics nomogram based on MRI was constructed, and its predictive performance was better than that of clinic-radiological factors model and radiomics signature, with the AUC [area under the curve] of the training set and the validation set were 0.78 (95%CI =0.67-0.89) and 0.77 (95%CI =0.59-0.94), respectively. DCA [decision curve analysis] showed that combined radiomics nomogram has potential clinical application value.

Conclusion

The MRI-based combined radiomics nomogram is a noninvasive preoperative prediction tool that combines clinic-radiological feature and radiomics signature and shows good predictive effect in distinguishing low-grade and high-grade bone chondrosarcoma, which may help clinicians to make accurate treatment plans.

Differentiation of Skull Base Chondrosarcomas, Chordomas, and Metastases: Utility of DWI and Dynamic Contrast-Enhanced Perfusion MR Imaging

BACKGROUND AND PURPOSE

Differentiation of skull base tumors, including chondrosarcomas, chordomas, and metastases, on conventional imaging remains a challenge. We aimed to test the utility of DWI and dynamic contrast-enhanced MR imaging for skull base tumors.

MATERIALS AND METHODS

Fifty-nine patients with chondrosarcomas, chordomas, or metastases between January 2015 and October 2021 were included in this retrospective study. Pretreatment normalized mean ADC and dynamic contrast-enhanced MR imaging parameters were calculated. The Kruskal-Wallis H test for all tumor types and the Mann-Whitney U test for each pair of tumors were used.

RESULTS

Fifteen chondrosarcomas (9 men; median age, 62 years), 14 chordomas (6 men; median age, 47 years), and 30 metastases (11 men; median age, 61 years) were included in this study. Fractional plasma volume helped distinguish all 3 tumor types (P = .003, <.001, and <.001, respectively), whereas the normalized mean ADC was useful in distinguishing chondrosarcomas from chordomas and metastases (P < .001 and P < .001, respectively); fractional volume of extracellular space, in distinguishing chondrosarcomas from metastases (P = .02); and forward volume transfer constant, in distinguishing metastases from chondrosarcomas/chondroma (P = .002 and .002, respectively) using the Kruskal-Wallis H test. The diagnostic performances of fractional plasma volume for each pair of tumors showed areas under curve of 0.86-0.99 (95% CI, 0.70-1.0); the forward volume transfer constant differentiated metastases from chondrosarcomas/chordomas with areas under curve of 0.82 and 0.82 (95% CI, 0.67-0.98), respectively; and the normalized mean ADC distinguished chondrosarcomas from chordomas/metastases with areas under curve of 0.96 and 0.95 (95% CI, 0.88-1.0), respectively.

CONCLUSIONS

DWI and dynamic contrast-enhanced MR imaging sequences can be beneficial for differentiating the 3 common skull base tumors.

The influence of site on the incidence and diagnosis of solitary central cartilage tumours of the femur. A 21st century perspective

OBJECTIVE

To determine the incidence of central cartilage tumours (CCTs) in the femur and the impact of site (proximal, mid and distal thirds) on tumour grade. To compare study results with historically published data.

MATERIALS AND METHODS

Retrospective review of solitary CCTs arising in the femur over the past 13 years. Data collected included location (proximal, mid and distal thirds) and final diagnosis in terms of tumour grade based on imaging features ± histology. Case material collected from three bone tumour textbooks provided historical data.

RESULTS

430 solitary CCTs were included in the femur. 73% cases arose in the distal, 3.7% in the mid and 23% in the proximal femur. The ratio of "benign" (combining enchondroma and atypical cartilaginous tumour (ACT)) to higher grade chondrosarcoma (CS) was 11:1 in the distal, 1:1 in the mid and 1:1.5 in the proximal femur, the distribution of benign to malignant tumours being significantly different between the regions (F test, p < 0.05). Comparison with historical data showed a reversal of the benign (enchondroma) to malignant (ACT and higher grade CS) of 30%:70%-84%:16% in the current series.

CONCLUSIONS

The site of origin of a CCT in the femur has an impact on final diagnosis with CS uncommon in the distal as compared with the mid and proximal femur. This is in contradistinction to historical data where the incidence of CS exceeded that of enchondroma at all sites.

Dynamic Contrast Enhanced Study in Multiparametric Examination of the Prostate—Can We Make Better Use of It?

We sought to investigate whether quantitative parameters from a dynamic contrast-enhanced study can be used to differentiate cancer from normal tissue and to determine a cut-off value of specific parameters that can predict malignancy more accurately, compared to the obturator internus muscle as a reference tissue. This retrospective study included 56 patients with biopsy proven prostate cancer (PCa) after multiparametric magnetic resonance imaging (mpMRI), with a total of 70 lesions; 39 were located in the peripheral zone, and 31 in the transition zone. The quantitative parameters for all patients were calculated in the detected lesion, morphologically normal prostate tissue and the obturator internus muscle. Increase in the K_trans value was determined in lesion-to-muscle ratio by 3.974368, which is a cut-off value to differentiate between prostate cancer and normal prostate tissue, with specificity of 72.86% and sensitivity of 91.43%. We introduced a model to detect prostate cancer that combines K_trans lesion-to-muscle ratio value and iAUC lesion-to-muscle ratio value, which is of higher accuracy compared to individual variables. Based on this model, we identified the optimal cut-off value with 100% sensitivity and 64.28% specificity. The use of quantitative DCE pharmacokinetic parameters compared to the obturator internus muscle as reference tissue leads to higher diagnostic accuracy for prostate cancer detection.

Update on the imaging features of the enchondromatosis syndromes

Ollier disease and Maffucci syndrome are the commonest enchondromatosis subtypes, arising from non-hereditary mutations in the IDH1 and IDH2 genes, presenting in childhood and being characterised by multiple enchondromas. Maffucci syndrome also includes multiple soft tissue haemangiomas. Aside from developing bony masses, osseous deformity and pathological fracture, ~ 40% of these patients develop secondary central chondrosarcoma, and there is increased risk of non-skeletal malignancies such as gliomas and mesenchymal ovarian tumours. In this review, we outline the molecular genetics, pathology and multimodality imaging features of solitary enchondroma, Ollier disease and Maffucci syndrome, along with their associated skeletal complications, in particular secondary chondrosarcoma. Given the lifelong risk of malignancy, imaging follow-up will also be explored. Metachondromatosis, a rare enchondromatosis subtype characterised by enchondromas and exostoses, will also be briefly outlined.

Assessment of central cartilaginous tumor of the appendicular bone: inter-observer and intermodality agreement and comparison of diagnostic performance of CT and MRI

BACKGROUND

Diagnostic performance, inter-observer agreement, and intermodality agreement between computed tomography (CT) and magnetic resonance imaging (MRI) in the depiction of the major distinguishing imaging features of central cartilaginous tumors have not been investigated.

PURPOSE

To determine the inter-observer and intermodality agreement of CT and MRI in the evaluation of central cartilaginous tumors of the appendicular bones, and to compare their diagnostic performance.

MATERIAL AND METHODS

Two independent radiologists retrospectively reviewed preoperative CT and MRI. Inter-observer and intermodality agreement between CT and MRI in the assessment of distinguishing imaging features, including lesion size, deep endosteal scalloping, cortical expansion, cortical disruption, pathologic fracture, soft tissue extension, and peritumoral edema, were evaluated. The agreement with histopathology and the accuracy of the radiologic diagnoses made with CT and MRI were also analyzed.

RESULTS

A total of 72 patients were included. CT and MRI showed high inter-observer and intermodality agreements with regard to size, deep endosteal scalloping, cortical expansion, cortical disruption, and soft tissue extension (ICC = 0.96-0.99, k = 0.60-0.90). However, for the evaluation of pathologic fracture, MRI showed only moderate inter-observer agreement (k = 0.47). Peritumoral edema showed only fair intermodality agreement (k = 0.28-0.33) and moderate inter-observer agreement (k = 0.46) on CT. Both CT and MRI showed excellent diagnostic performance, with high agreement with the histopathology (k = 0.89 and 0.87, respectively) and high accuracy (91.7% for both CT and MRI).

CONCLUSION

CT and MRI showed high inter-observer and intermodality agreement in the assessment of several distinguishing imaging features of central cartilaginous tumors of the appendicular bones and demonstrated comparable diagnostic performance.

Benign Hand Tumors (Part I): Cartilaginous and Bone Tumors

Background: Benign tumors of the hand present in a wide array of histological subtypes and compose most of the bony tissue tumors in the hand. This study evaluates the characteristics and treatment of benign bone tumors in light of one institution's experience. Methods: Histologically confirmed benign tumors of the hand were retrospectively identified using International Classification of Diseases codes from 1992 to 2015. A medical chart review was conducted to collect patient characteristics and tumor epidemiology and treatment. Results: A total of 155 benign bone tumors were identified. The median age of patients at the time of surgery was 39.9 ± 12.8 years. All bone tumors were located in the digits, and most were treated by intralesional curettage (n = 118, 76%). Pathologic fractures occurred in 79 bone tumors (51%). Conclusion: Enchondromas (n = 118, 76%) were the most common bone tumor in this series, whereas giant cell tumors were the most destructive and also had the highest recurrence rate (40%). Awareness of tumor features may help physicians with diagnosis, and awareness of recurrence rates is important when counseling patients.

Atypical Cartilaginous Tumors: Trends in Management

INTRODUCTION

Chondrosarcomas are the most common primary bone malignancy in adults within the United States. Low-grade chondrosarcomas of the long bones, now referred to as atypical cartilaginous tumors (ACTs), have undergone considerable changes in recommended management over the past 20 years, although controversy remains. Diagnostic needle biopsy is recommended only in ambiguous lesions that cannot be clinically diagnosed with a multidisciplinary team. Local excision is preferred due to better functional and equivalent oncologic outcomes. We sought to determine whether these changes are reflected in reported management of ACTs.

METHODS

The National Cancer Database (NCDB) 2004 to 2016 was queried for ACTs of the long bones. Reported patient demographics and tumor clinicopathologic findings were extracted and compared between patients who underwent local excision versus wide resection.

RESULTS

We identified 1174 ACT patients in the NCDB. Of these, 586 underwent local excision and 588 underwent wide resection. No significant differences were found in patient demographics. No significant change was found in the reported percentage of diagnostic biopsies or wide resections performed over time. After multivariate regression, the single greatest predictor of performing wide resection on an ACTs was presenting tumor size.

DISCUSSION

Evaluation of the NCDB demonstrated that despite changes in the recommended management of ACTs, there has not been a significant change in surgical treatment over time. Surgeons have been performing diagnostic biopsies and wide resections at similar to historical rates. Persistency of these practices may be due to presenting tumor size, complex anatomic location, uncertainty of underlying tumor grade, or patient choice as part of clinical shared decision making. The authors anticipate that the rate of biopsies and wide resections performed will decrease over time as a result of improvements in advanced imaging and the implementation of recently updated clinical practice guidelines.

Diagnostic Value of CT- and MRI-Based Texture Analysis and Imaging Findings for Grading Cartilaginous Tumors in Long Bones

Objective

To confirm the diagnostic performance of computed tomography (CT)-based texture analysis (CTTA) and magnetic resonance imaging (MRI)-based texture analysis for grading cartilaginous tumors in long bones and to compare these findings to radiological features.

Materials and Methods

Twenty-nine patients with enchondromas, 20 with low-grade chondrosarcomas and 16 with high-grade chondrosarcomas were included retrospectively. Clinical and radiological information and 9 histogram features extracted from CT, T1WI, and T2WI were evaluated. Binary logistic regression analysis was performed to determine predictive factors for grading cartilaginous tumors and to establish diagnostic models. Another 26 patients were included to validate each model. Receiver operating characteristic (ROC) curves were generated, and accuracy rate, sensitivity, specificity and positive/negative predictive values (PPV/NPV) were calculated.

Results

On imaging, endosteal scalloping, cortical destruction and calcification shape were predictive for grading cartilaginous tumors. For texture analysis, variance, mean, perc.01%, perc.10%, perc.99% and kurtosis were extracted after multivariate analysis. To differentiate benign cartilaginous tumors from low-grade chondrosarcomas, the imaging features model reached the highest accuracy rate (83.7%) and AUC (0.841), with a sensitivity of 75% and specificity of 93.1%. The CTTA feature model best distinguished low-grade and high-grade chondrosarcomas, with accuracies of 71.9%, and 80% in the training and validation groups, respectively; T1-TA and T2-TA could not distinguish them well. We found that the imaging feature model best differentiated benign and malignant cartilaginous tumors, with an accuracy rate of 89.2%, followed by the T1-TA feature model (80.4%).

Conclusions

The imaging feature model and CTTA- or MRI-based texture analysis have the potential to differentiate cartilaginous tumors in long bones by grade. MRI-based texture analysis failed to grade chondrosarcomas.

Effects of Interobserver Variability on 2D and 3D CT- and MRI-Based Texture Feature Reproducibility of Cartilaginous Bone Tumors

This study aims to investigate the influence of interobserver manual segmentation variability on the reproducibility of 2D and 3D unenhanced computed tomography (CT)- and magnetic resonance imaging (MRI)-based texture analysis. Thirty patients with cartilaginous bone tumors (10 enchondromas, 10 atypical cartilaginous tumors, 10 chondrosarcomas) were retrospectively included. Three radiologists independently performed manual contour-focused segmentation on unenhanced CT and T1-weighted and T2-weighted MRI by drawing both a 2D region of interest (ROI) on the slice showing the largest tumor area and a 3D ROI including the whole tumor volume. Additionally, a marginal erosion was applied to both 2D and 3D segmentations to evaluate the influence of segmentation margins. A total of 783 and 1132 features were extracted from original and filtered 2D and 3D images, respectively. Intraclass correlation coefficient ≥ 0.75 defined feature stability. In 2D vs. 3D contour-focused segmentation, the rates of stable features were 74.71% vs. 86.57% (p < 0.001), 77.14% vs. 80.04% (p = 0.142), and 95.66% vs. 94.97% (p = 0.554) for CT and T1-weighted and T2-weighted images, respectively. Margin shrinkage did not improve 2D (p = 0.343) and performed worse than 3D (p < 0.001) contour-focused segmentation in terms of feature stability. In 2D vs. 3D contour-focused segmentation, matching stable features derived from CT and MRI were 65.8% vs. 68.7% (p = 0.191), and those derived from T1-weighted and T2-weighted images were 76.0% vs. 78.2% (p = 0.285). 2D and 3D radiomic features of cartilaginous bone tumors extracted from unenhanced CT and MRI are reproducible, although some degree of interobserver segmentation variability highlights the need for reliability analysis in future studies.

7 Tesla Chlorine (35Cl) and Sodium (23Na) MR Imaging of an Enchondroma

We demonstrated the feasibility of 7 Tesla sodium (²³Na) and chlorine (³⁵Cl) MRI of a solitary enchondroma. For this, we established dedicated sequences on a 7-Tesla whole-body system with the following key parameters for ³⁵Cl MRI: TE/TR = 0.35/60 ms, T_RO = 5 ms, α = 90°, Δx³ = (6 mm)³, 3 averages, T_acq = 30 min and for ²³Na MRI: TE/TR = 0.4/101 ms, T_RO = 10ms; α = 90°; Δx³ = (1.9 mm)³, 3 averages, T_acq = 30 min 18 s. The measured apparent Na⁺ concentration was 255 mmol/l and was approximately 7-fold higher than the apparent Cl^- concentration with about 36 mmol/l. Additionally, repeated proton MRI examinations demonstrated constant but subtle growth (≈ 0.65 ml/year) over 14 years. In conclusion, enchondromas obviously have a high contrast-to-noise ratio when compared with the normal bone marrow in ²³Na and ³⁵Cl MRI, which may contribute to detection and differentiation in unclear or subtle cases. KEY POINTS:: · High magnetic field strengths (e. g., 7 Tesla) enable sodium (23Na) and chlorine (35Cl) MRI of solitary cartilage-forming tumors like enchondromas with nominal spatial resolutions of (1.9 mm)3 (23Na MRI) and (6 mm)3 (35Cl MRI).. · Measured median tumoral apparent Na+ and Cl- concentrations were nearly 13 times higher and 3 times higher than in normal muscle tissue, respectively.. · Enchondromas have a high contrast-to-noise-ratio when compared with the normal bone marrow in 23Na and 35Cl MRI, which may contribute to detection and differentiation in unclear or subtle cases.. CITATION FORMAT: · Weber M, Seyler L, Nagel AM. 7 Tesla Chlorine (35Cl) and Sodium (23Na) MR Imaging of an Enchondroma. Fortschr Röntgenstr 2021; DOI: 10.1055/a-1472-6730.

MRI features of low-grade and high-grade chondrosarcoma in enchondromatosis

OBJECTIVE

To identify magnetic resonance imaging (MRI) features which aid differentiation of low-grade chondral tumours (LGCT-enchondroma and grade 1 chondrosarcoma) from high-grade chondral tumours (HGCT) in patients with enchondromatosis.

MATERIALS AND METHOD

Approval from our local Research and Innovation Centre of The Institute of Orthopaedics was gained. Patients with enchondromatosis who had biopsy and/or resection of chondral lesions over a 13-year period were identified. The pre-biopsy MRI study was assessed by two experienced musculoskeletal radiologists for tumour origin (intramedullary or surface), cortical expansion, cortical destruction, bone marrow oedema, periosteal reaction, soft tissue mass and soft tissue oedema. MRI features were compared with the final histopathological diagnosis.

RESULTS

The study group comprised 25 males and 16 females, with a mean age of 34.9 years (range 6-81 years). Fifty-nine lesions were assessed (12 patients had > 1 tumour treated), including 43 LGCT and 16 HGCT. Significant MRI features suggesting malignant transformation to HGCT for both observers included bone oedema (p = < 0.001 and 0.002), periosteal reaction (p = 0.01) and soft tissue oedema (p = 0.001 and 0.05). Cortical destruction and soft tissue mass were predictors of HGCT in major long bones, but no significant differentiating features were identified in the hands and feet.

CONCLUSION

The presence of bone oedema, periosteal reaction and soft tissue oedema on MRI may indicate a high-grade malignant transformation of chondral tumours in patients with enchondromatosis.

Chondrosarcoma-from Molecular Pathology to Novel Therapies

Chondrosarcoma (CHS) is the second most common primary malignant bone sarcoma. Overall survival and prognosis of this tumor are various and often extreme, depending on histological grade and tumor subtype. CHS treatment is difficult, and surgery remains still the gold standard due to the resistance of this tumor to other therapeutic options. Considering the role of differentiation of CHS subtypes and the need to develop new treatment strategies, in this review, we introduced a multidisciplinary characterization of CHS from its pathology to therapies. We described the morphology of each subtype with the role of immunohistochemical markers in diagnostics of CHS. We also summarized the most frequently mutated genes and genome regions with altered pathways involved in the pathology of this tumor. Subsequently, we discussed imaging methods and the role of currently used therapies, including surgery and the limitations of chemo and radiotherapy. Finally, in this review, we presented novel targeted therapies, including those at ongoing clinical trials, which can be a potential future target in designing new therapeutics for patients with CHS.

Conventional Cartilaginous Tumors: Evaluation and Treatment

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Enchondromas are benign cartilaginous lesions that rarely require surgical intervention.

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Atypical cartilaginous tumors (ACTs), also referred to as grade-1 chondrosarcomas, may be managed without any intervention or with extended intralesional curettage and bone-void filling.

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High-grade chondrosarcomas, or grade-2 and 3 chondrosarcomas, should be managed aggressively with wide resection.

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Chemotherapy and radiation do not currently play a role in the treatment of chondrosarcomas.

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Differentiating an enchondroma from an ACT and an ACT from a high-grade chondrosarcoma can be difficult and requires clinical experience, radiographic and advanced imaging, and possibly a biopsy. Ultimately, a multidisciplinary team that includes a musculoskeletal oncologist, a radiologist, and a pathologist is needed to make the most appropriate diagnosis and treatment plan for each patient.

MRI-histopathological correlation in paediatric conventional central chondrosarcoma: a report of 17 cases

OBJECTIVE

To describe the MRI features of paediatric conventional central chondrosarcoma (CC-CS) and correlate with histological grade.

MATERIALS AND METHODS

A retrospective review of children/adolescents with histologically confirmed CC-CS. Data collected included age, sex, skeletal location, and histology from needle biopsy or resection, which was classified as atypical cartilaginous tumours/grade 1 CS (ACT/Gd 1 CS), high-grade chondrosarcoma (HGCS), and dedifferentiated chondrosarcoma (DD-CS). MRI studies were reviewed independently by 2 radiologists blinded to the histology grade, who graded the tumours as ACT/Gd 1 CS, HGCS, and DD-CS based on MRI features.

RESULTS

The study included 7 males and 10 females with mean age 13.9 years (range 6-18 years). Tumours were located in the femur (n = 6), humerus (n = 3), tibia, ilium, scapula, and ulna (n = 1 each), and the small bones of the hands or feet (n = 4). Final histology grade was ACT/Gd 1 CS in 15 cases and HGCS in 2 (both grade 1 CS with focal transition to grade 2), 15 based on surgical specimens, 1 based on open biopsy, and 1 on needle biopsy alone. Predicted MRI grade for the 2 readers was ACT/Gd 1 CS in 11 cases each and HGCS in 6 cases each, indicating a mismatch between predicted MRI grade and histological grade in 8 (47%) cases (4 cases with one reader mismatch and 4 cases with both).

CONCLUSIONS

MRI findings in paediatric CC-CS may be misleading, showing features suggestive of HGCS 7 of 17 (41.2%) of cases. This should be taken into consideration when planning surgical treatment.

The role of imaging in differentiating low-grade and high-grade central chondral tumours

Chondrosarcoma is a malignant cartilage matrix-producing tumour. Those arising de novo are called primary chondrosarcomas and are the second commonest primary malignant bone tumours. Numerous types of primary chondrosarcoma exist, namely conventional central (intramedullary), periosteal (juxta-cortical), clear cell, mesenchymal, and dedifferentiated. The biologic aggressiveness, prognosis and thus management of chondrosarcoma are dependent on the histological sub-type and grade. Accurate pre-operative diagnosis is therefore essential in determining management and outcome which requires a multidisciplinary approach taking into account clinical features, imaging findings and histopathology. In this review, we present the pertinent multimodality imaging features which aid in the differentiation of low-grade and high-grade conventional central chondrosarcoma.

Solitary enchondromas-diagnosis and surveillance : Danish guidelines

Enchondromas (EC) are frequent incidental findings on magnetic resonance imaging (MRI) performed for the diagnosis of joint pathology, especially observed on MRI examinations of the knee and shoulder. Enchondroma has potential for malignant transformation to chondrosarcoma (CS), and it may be difficult to distinguish EC from low-malignant CS on the basis of imaging or histopathology studies. Therefore, EC is mostly followed up to monitor any growth and/or changes indicating aggressive tumor.There is no consensual evidence on when and how to follow up patients with EC with regard to potential malignant transformation. Therefore, the Danish Multidisciplinary Cancer Groups initiated and supported the elaboration of Danish guidelines in 2020 based on a literature review. The guidelines are presented here, in addition to a summary of the background literature.

Chondrogenic Bone Tumors: The Importance of Imaging Characteristics

BACKGROUND

 Chondrogenic tumors are the most frequent primary bone tumors. Malignant chondrogenic tumors represent about one quarter of malignant bone tumors. Benign chondrogenic bone tumors are frequent incidental findings at imaging. Radiological parameters may be helpful for identification, characterization, and differential diagnosis.

METHODS

 Systematic PubMed literature research. Identification and review of studies analyzing and describing imaging characteristics of chondrogenic bone tumors.

RESULTS AND CONCLUSIONS

 The 2020 World Health Organization (WHO) classification system differentiates between benign, intermediate (locally aggressive or rarely metastasizing), and malignant chondrogenic tumors. On imaging, typical findings of differentiated chondrogenic tumors are lobulated patterns with a high signal on T2-weighted magnetic resonance imaging (MRI) and ring- and arc-like calcifications on conventional radiography and computed tomography (CT). Depending on the entity, the prevalence of this chondrogenic pattern differs. While high grade tumors may be identified due to aggressive imaging patterns, the differentiation between benign and intermediate grade chondrogenic tumors is challenging, even in an interdisciplinary approach.

KEY POINTS

  · The WHO defines benign, intermediate, and malignant chondrogenic bone tumors. · Frequent benign tumors: osteochondroma and enchondroma; Frequent malignant tumor: conventional chondrosarcoma. · Differentiation between enchondroma versus low-grade chondrosarcoma is challenging for radiologists and pathologists. · Pain, deep scalloping, cortical destruction, bone expansion, soft tissue component: favor chondrosarcoma. · Potential malignant transformation of osteochondroma: progression after skeletal maturity, cartilage cap thickness (> 2 cm adult; > 3 cm child). · Potentially helpful advanced imaging methods: Dynamic MRI, texture analysis, FDG-PET/CT.

CITATION FORMAT

· Engel H, Herget GW, Füllgraf H et al. Chondrogenic Bone Tumors: The Importance of Imaging Characteristics. Fortschr Röntgenstr 2021; 193: 262 - 274.

Bone Scans Have Little Utility in the Evaluation of Well-Differentiated Cartilaginous Lesions of the Humerus

In the humerus, pain is a poor guide for differentiating between benign enchondromas and malignant well-differentiated chondrosarcomas. Radionuclide bone scans often are used, and chondrosarcomas reliably show increased uptake. However, it remains to be seen whether enchondromas consistently have negative findings on bone scans, which would provide reliable differentiation from malignant lesions. Imaging and medical records were reviewed for patients who underwent radionuclide bone scans for enchondroma of the humerus at one academic medical center over a period of 7 years. Bivariate logistic regression was used to determine the association of bone scan results with the finding of endosteal scalloping on radiographs and magnetic resonance imaging (MRI) scans. During initial evaluation, 25 patients who had enchondroma of the humerus underwent radionuclide bone scans. No patients showed progression of lesions during an average follow-up of 69 weeks. On bone scan, 18 (72%) had significantly positive findings, 5 (20%) had mildly positive findings, and 2 (8%) had negative findings. Of the 22 patients who underwent MRI scans, 4 showed endosteal scalloping and none showed aggressive features. No statistically significant association was seen between significantly positive (P=.299) or mildly positive findings on bone scans (P=.810) and the finding of endosteal scalloping on radiographs or MRI scans. Enchondromas rarely showed negative findings on bone scans, and bone scan findings did not correlate with the findings on radiographs or MRI scans. The diagnosis of enchondroma can be made based on clinical and radiographic findings, and the added utility of bone scans does not justify their regular use. [Orthopedics. 2020;43(6):e498-e502.].

Revisiting the WHO classification system of bone tumours: emphasis on advanced magnetic resonance imaging sequences. Part 2

Similarly to soft tissue tumours, the World Health Organisation (WHO) classification categorises bone tumours based on their similarity to normal adult tissue. The most recent WHO classification provides an updated classification scheme that integrates the biological behaviour of bone tumours, particularly cartilage-forming tumours, and tumours are now further subdivided as benign, intermediate (locally aggressive or rarely metastasising), and malignant. Radiologists play an important role in the detection and initial characterisation of bone tumours, with careful analysis of their matrix mineralisation, location, and overall anatomic extent including extra-compartmental extension and neurovascular invasion. Radiography remains central to the detection and characterisation of bone tumours; however, magnetic resonance imaging (MRI) is the ideal modality for local staging. This review will discuss the most recent updates to the WHO classification of bone tumours that are relevant to radiologists in routine clinical practice. The utility of advanced MRI sequences such as diffusion-weighted imaging, dynamic contrast enhanced sequences, and magnetic resonance spectroscopy that may provide insight into the biological behaviour of various bone tumours is highlighted.

An imaging protocol for the management of central cartilage tumours of the proximal fibula

AIM

To retrospectively review a series of solitary central cartilage tumours (CCTs) of the proximal fibula and propose an imaging protocol for their management.

MATERIALS AND METHODS

Over 11 years, 48 patients were identified with a CCT of the proximal fibula. The initial magnetic resonance imaging (MRI) and follow-up imaging were assessed for tumour length, endosteal scalloping, or aggressive/malignant features. Each case was categorised according to the Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP). The final diagnosis and outcome were reviewed to establish an appropriate imaging protocol for the management of similar cases in the future.

RESULTS

The final diagnosis based on imaging alone or imaging and histopathology was enchondroma in 46 cases (96%) and atypical cartilage tumour (ACT)/low-grade chondrosarcoma in two (4%). Using the BACTIP classification, the majority were type IC (48%) with type IA the second commonest (24%). Of 19 that underwent follow-up MRI, only two revealed any increase in length, neither of which was shown to be malignant. No cases re-presented later with evidence of malignant transformation.

CONCLUSION

There has been a significant increase in the number of CCTs of the proximal fibula referred to Royal Orthopaedic Hospital, Birmingham, over the past decade. This can largely be attributed to the increased use of MRI. The majority were benign with only 4% classified as an ACT. A modified BACTIP, the Fibular Atypical Cartilage Tumour Imaging Protocol (FACTIP) is presented, indicating which cases would benefit from follow-up imaging and which require referral to a specialist orthopaedic oncology service.

Quantitative SPECT/CT for differentiating between enchondroma and grade I chondrosarcoma

Although differentiation between central chondroid tumors is important, their parallelism makes it a diagnostic conundrum for clinicians and radiologists. The objective of this study was to evaluate the efficiency of quantitative single photon emission computed tomography (SPECT)/computed tomography (CT) in differentiating grade I chondrosarcomas from enchondromas. We reviewed SPECT/CT images of patients with enchondromas and grade I chondrosarcomas arising in the long bones. Volume, mean standardized uptake value (SUVmean), and maximum standardized uptake value (SUVmax) of tumors were calculated from SPECT/CT images. In addition, clinical characteristics and radiological information were assessed. Of a total of 34 patients, 14 had chondrosarcomas. Chondrosarcoma group had significantly larger volume, and higher SUVmean and SUVmax of tumors than enchondroma group. There was no significant difference in age and tumor size between two groups. Areas under the receiver-operating characteristic curve (AUCs) for tumor volume, SUVmean, and SUVmax were 0.727, 0.757, and 0.875. In pairwise analyses, SUVmax had larger AUC than SUVmean (p = 0.0216). With a cut-off value of 15.6 for SUVmax, its sensitivity and specificity were 86% and 75% for differentiating between enchondroma and grade I chondrosarcoma. Quantitative SPECT/CT is a potential method to differentiate grade I chondroarcomas from enchondromas in patients with central chondroid tumors.

MRI radiomics-based machine-learning classification of bone chondrosarcoma

PURPOSE

To evaluate the diagnostic performance of machine learning for discrimination between low-grade and high-grade cartilaginous bone tumors based on radiomic parameters extracted from unenhanced magnetic resonance imaging (MRI).

METHODS

We retrospectively enrolled 58 patients with histologically-proven low-grade/atypical cartilaginous tumor of the appendicular skeleton (n = 26) or higher-grade chondrosarcoma (n = 32, including 16 appendicular and 16 axial lesions). They were randomly divided into training (n = 42) and test (n = 16) groups for model tuning and testing, respectively. All tumors were manually segmented on T1-weighted and T2-weighted images by drawing bidimensional regions of interest, which were used for first order and texture feature extraction. A Random Forest wrapper was employed for feature selection. The resulting dataset was used to train a locally weighted ensemble classifier (AdaboostM1). Its performance was assessed via 10-fold cross-validation on the training data and then on the previously unseen test set. Thereafter, an experienced musculoskeletal radiologist blinded to histological and radiomic data qualitatively evaluated the cartilaginous tumors in the test group.

RESULTS

After feature selection, the dataset was reduced to 4 features extracted from T1-weighted images. AdaboostM1 correctly classified 85.7 % and 75 % of the lesions in the training and test groups, respectively. The corresponding areas under the receiver operating characteristic curve were 0.85 and 0.78. The radiologist correctly graded 81.3 % of the lesions. There was no significant difference in performance between the radiologist and machine learning classifier (P = 0.453).

CONCLUSIONS

Our machine learning approach showed good diagnostic performance for classification of low-to-high grade cartilaginous bone tumors and could prove a valuable aid in preoperative tumor characterization.

Evaluating the scope of intramedullary invasion of malignant bone tumor by DCE-MRI quantitative parameters in animal study

The purpose was to analyze the value of quantitative parameters of DCE-MRI in evaluating micro-infiltration of malignant bone tumors.

METHODS

Thirty-nine New Zealand white rabbits were used to establish malignant bone tumor models by implanting VX2 tumor fragments into the right tibiae. After three weeks, models were examined by conventional MRI and DCE-MRI; then the right tibiae were cut into sagittal sections and partitioned into histology slices for comparison with microscopic findings. Micro-infiltration groups were selected and the range of infiltration was determined under the microscope, and corresponding DCE images analyzed to obtain the quantitative parameters include Ktrans, Kep, v_e and v_p in parenchyma areas, micro-infiltration areas and simple edema areas. One-way ANOVA was used to compare the differences of the parameters between the three areas. Receiver operating characteristic curves (ROCs) were plotted to determine the accuracy of different parameters by area under curves (AUCs).

RESULTS

22 cases (22/39, 56.4%) were included in the micro-infiltration group and the infiltration depth ranged from 1.3 mm to 4.6 mm, with an average depth of 3.2 mm ± 0.8 mm. The statistical results of quantitative parameters in the three areas were as follows: Ktrans values were (0.494 ± 0.052), (0.403  ±  0.049), (0.173 ± 0.047) min^-1 (p = =0.000), Kep values were (1.959 ± 0.65), (1.528 ± 0.372), (1.174 ± 0.486) min^-1 (p = =0.000), v_e values were (0.247 ± 0.068), (0.283 ± 0.057), (0.168 ± 0.062) min^-1 (p = =0.000), v_p values were (0.125 ± 0.036), (0.108 ± 0.033), (0.098 ± 0.025) min^-1 (p = =0.022), respectively. Ktrans and Kep values had significant difference in the three areas after comparing between-groups, respectively. However, there were no significant difference in v_p values between parenchyma and micro-infiltration areas (p = =0.078), micro-infiltration and simple edema areas (p = =0.315), and v_e values between parenchyma and micro-infiltration areas (p = =0.056). The v_e values were higher in parenchyma and micro-infiltration areas then simple edema areas. Ktrans had highest accuracy in differentiating different areas (AUC > 0.9), respectively.

CONCLUSION

Quantitative parameters Ktrans, Kep and v_e can assess the extent of intramedullary invasion of malignant bone tumors. Ktrans have highest accuracy in differentiating different regions.

Can clinical radiomics nomogram based on 3D multiparametric MRI features and clinical characteristics estimate early recurrence of pelvic chondrosarcoma?

BACKGROUND

Chondrosarcoma (CS) is the second most common primary malignant bone tumor, with a relatively high recurrence rate. However, an effective method that estimates whether pelvic CS will recur after surgery, which influences the formulation of a clinical treatment plan, remains lacking.

PURPOSE

To develop and validate a clinical radiomics nomograms based on 3D multiparametric magnetic resonance imaging (mpMRI) features and clinical characteristics that could estimate early recurrence (ER) (≤1 year) of pelvic CS.

STUDY TYPE

Retrospective.

POPULATION

In all, 103 patients (ER = 41, non-ER = 62) with histologically proven CS were retrospectively analyzed and divided into a training set (n = 72) and a validation set (n = 31).

FIELD STRENGTH/SEQUENCE

3.0T axial T₁ -weighted (T₁ -w), T₂ -weighted (T₂ -w), diffusion weighted imaging (DWI), contrast-enhanced T₁ -weighted (CET₁ -w).

ASSESSMENT

Risk factors (sex, age, type, grade, resection margins, etc.) associated with ER were evaluated. Five individual models based on T₁ -w, T₂ -w, DWI, CET₁ -w, and clinical data were built. Then we compared the performance of models based on T₁ -w, T₂ -w, CET₁ -w and their combination. Lastly, two nomograms based on the best model + clinical data and DWI + clinical data were built.

STATISTICAL TESTS

The area under the receiver operating characteristic curve (AUC) and accuracy (ACC) were used to evaluate different models.

RESULTS

Grade was the most important univariate clinical predictor of ER of pelvic CS patients (odds ratio [OR]1 = 4.616, OR2 = 8.939, P < 0.05). T₁ -w + T₂ -w + CET₁ -w had a significantly higher performance than CET₁ -w in the training set (P = 0.01). Radiomics features are more important than clinical characteristics in clinical radiomics nomograms, especially for multisequence combined features (OR = 3.208, P < 0.01). Clinical radiomics nomogram based on combined features (T₁ -w + T₂ -w + CET₁ -w) + clinical data achieved an AUC of 0.891 and ACC of 0.857, followed by DWI + clinical data (AUC = 0.882, ACC = 0.760) in the validation set.

DATA CONCLUSION

The clinical radiomics nomogram had good performance in estimating ER of pelvic CS patients, which would be helpful in clinical decision-making.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:435-445.

Outcome of conservative and surgical treatment of enchondromas and atypical cartilaginous tumors of the long bones: retrospective analysis of 228 patients

Background

Sufficient data on outcome of patients with clinically and radiologically aggressive enchondromas and atypical cartilaginous tumors (ACT) is lacking. We therefore analyzed both conservatively and surgically treated patients with lesions, which were not distinguishable between benign enchondroma and low-grade malignant ACT based upon clinical and radiologic appearance.

Methods

The series included 228 consecutive cases with a follow-up > 24 months to assess radiological, histological, and clinical outcome including recurrences and complications. Pain, satisfaction, functional limitations, and the musculoskeletal tumor society (MSTS) score were evaluated to judge both function and emotional acceptance at final follow-up.

Results

Follow-up took place at a mean of 82 (median 75) months. The 228 patients all had comparable clinical and radiological findings. Of these, 153 patients were treated conservatively, while the other 75 patients underwent intralesional curettage. Besides clinical and radiological aggressiveness, most lesions were histologically judged as benign enchondromas. 9 cases were determined to be ACT, while the remaining 7 cases had indeterminate histology. After surgery, three patients developed a recurrence, and a further seven had complications of which six were related to osteosynthesis. Both groups had excellent and almost equal MSTS scores of 96 and 97%, respectively, but significantly less functional limitations were found in the non-surgery group. Further sub-analyses were performed to reduce selection bias. Sub-analysis of histologically diagnosed enchondromas in the surgery group found more pain, less function, and worse MSTS score compared to the non-surgery group. Sub-analysis of smaller lesions (< 4.4 cm) did not show significant differences. In contrast, larger lesions displayed significantly worse results after surgery compared to conservative treatment (enchondromas > 4.4 cm: MSTS score: 94.0% versus 97.3%, p = 0.007; pain 2.3 versus 0.8, p = 0.001). The majority of lesions treated surgically was filled with polymethylmethacrylate bone-cement, while the remainder was filled with cancellous-bone, without significant difference in clinical outcome.

Conclusion

Feasibility of intralesional curettage strategies for symptomatic benign to low-grade malignant chondrogenic tumors was supported. Surgery, however, did not prove superior compared to conservative clinical and radiological observation. Due to the low risk of transformation into higher-grade tumors and better functional results, more lesions might just be observed if continuous follow-up is assured.

Dynamic contrast-enhanced MRI perfusion of normal muscle in adult hips: Variation of permeability and semi-quantitative parameters

The purpose of this prospective study was to ascertain the degree of variation of semi-quantitative and permeability parameters on DCE-MRI of normally appearing striated muscles. Dynamic contrast-enhanced MRI of the right hip was performed in 20 women and 24 men. Mean age was 39.1 ± 12.4 years. Two regions of interest (ROI) were drawn in twelve muscles of anterior, medial and gluteal compartments: a free-form ROI covering the largest muscle section and a smaller elliptical ROI. Semi-quantitative and permeability parameters were calculated using the extended Tofts model. Statistical analysis was performed with a linear mixed model to assess perfusion parameters variation. Intra- and inter-observer agreements were assessed. The intra-observer agreement was considered to be good for free-form ROI (minimum Intra-Class Coefficient (ICC) = 0.72) and moderate for elliptical ROI (minimum ICC = 0.51), while the inter-observer agreement was considered to be bad in both cases (minimum ICC = 0.11). There was a high inter-individual variation in most of the perfusion parameters evaluated. The average coefficients of variation were: Time To Peak = 9%, Area Under the Curve = 44%, V_e = 61%, K_ep = 90%, Initial Slope = 99%, and K^trans = 128%. A considerable variation in resting muscle perfusion parameters was seen. This could lead to errors in the analysis of muscle DCE-MRI studies or oncologic/non oncologic studies using muscle as a referential. Further studies targeted on acquisition protocols and post-processing software are necessary to improve the performance of muscle MR perfusion.

Enchondromas and atypical cartilaginous tumors at the proximal humerus treated with intralesional resection and bone cement filling with or without osteosynthesis: retrospective analysis of 42 cases with 6 years mean follow-up

Background

Enchondromas and atypical cartilaginous tumors (ACT) are often located at the proximal humerus. Most lesions can be followed conservatively, but surgical resection may alleviate pain, avoid pathological fractures, and prevent transformation into higher grade chondrosarcomas. Rigorous intralesional resection and filling with polymethylmethacrylate bone cement has been proposed for enchondromas but also for ACT, as an alternative for extralesional resection. We intended to analyze radiological, clinical, and functional outcome of this strategy and compare bone cement without osteosynthesis to bone cement compound osteosynthesis, which has not been analyzed so far.

Methods

We retrospectively analyzed 42 consecutive patients (mean follow-up 73 months; range 8–224) after curettage and bone cement filling with or without osteosynthesis. Exclusion criteria were Ollier’s disease and cancellous bone filling. Twenty-five patients only received bone cement. Seventeen patients received additional proximal humerus plate for compound osteosynthesis to increase stability after curettage. Demographics and radiological and clinical outcome were analyzed including surgery time, blood loss, hospitalization, recurrences, and complications. An additional telephone interview at the final follow-up assessed postoperative satisfaction, pain, and function in the quick disabilities of the arm, shoulder, and hand (DASH) score and the Musculoskeletal Tumor Society (MSTS) score. Statistics included the Student T tests, Mann-Whitney U tests, and chi-square tests.

Results

No osteosynthesis compared to compound osteosynthesis showed smaller tumors (4.2 (± 1.5) cm versus 6.6 (± 3.0) cm; p = 0.005) and smaller bone cement fillings after curettage (5.7 (± 2.1) cm versus 9.6 (± 3.2) cm; p = 0.0001). A score evaluating preoperative scalloping and soft-tissue extension did not significantly differ (1.9 (± 0.9) versus 2.0 (± 1.0); rating scale 0–4; p = 0.7). Both groups showed high satisfaction (9.2 (± 1.5) versus 9.2 (± 0.9); p = 0.5) and low pain (1.0(±1.7) versus 1.9(±1.8); p = 0.1) in a rating scale from 0 to 10. Clinical and functional outcome was excellent for both groups in the DASH score (6.0 (± 11.8) versus 11.0 (± 13.2); rating scale 0–100; p = 0.2) and the MSTS score (29.0 (± 1.7) versus 28.7 (± 1.1); rating scale 0–30; p = 0.3). One enchondroma recurrence was found in the group without osteosynthesis. Complications (one fracture and one intra-articular screw) were only detected after osteosynthesis. Osteosynthesis had longer surgery time (70 (± 21) min versus 127 (± 22) min; p < 0.0001), more blood loss (220 (± 130) ml versus 460 (± 210) ml; p < 0.0001), and longer stay in the hospital (6 (± 2) days versus 8 (± 2) days; p = 0.004).

Conclusions

Intralesional tumor resection was oncologically safe and clinically successful with or without osteosynthesis. Osteosynthesis did not reduce the risk for fracture but was more invasive.

Intralesional vs. extralesional procedures for low-grade central chondrosarcoma: a systematic review of the literature

INTRODUCTION

Chondroid lesions are very common bone tumors. In most cases, they are benign enchondromas (EC) and, in a minor percentage, chondrosarcomas (CSs), the malignant counterpart. In the latter cases, surgery is the mainstay treatment, because they are chemo- and radio-resistant unless dedifferentiation occurs. If resection is recognized as the gold standard for intermediate-, high-grade tumors, and for low-grade chondrosarcoma (LG-CS) located in the spine and pelvis to reduce the risk of local recurrence, there is still no consensus in literature on the treatment of central low-grade chondrosarcoma (cLG-CS) located in the limbs. Our aim is to perform a review of literature on evidence supporting this approach or not.

MATERIALS AND METHODS

An electronic research of the medical archives was carried out in March 2017 seeking papers evaluating the results of curettage and resection in cLG-CS.

RESULTS

We selected 13 studies corresponding to our criteria. Unfortunately, they were descriptive, retrospective, non-randomized studies. We identified a population of 471 patients for a total of 473 low-grade chondrosarcomas. Two hundred and ninety-nine lesions were treated with curettage and 174 with wide surgery. The two groups were not homogeneous for diagnosis, size and staging, so no comparison between resection and curettage was possible. The global weighted average percentage of local recurrence was 6.7% (20 cases) and 10.9% (19 cases) after curettage and resection, respectively. No cases of metastasis were reported in the group treated with intralesional surgery, compared to five cases reported in the group treated with resection. Indications for surgery were given in most cases based on symptoms and imaging.

CONCLUSIONS

The absence of a preoperative histological diagnosis and the lack of a scientific method to conduct the studies do not sufficiently support curettage for low-grade chondrosarcomas. In the absence of this, resection must be considered a general rule for every malignancy. In our opinion, based on the low biological growth rate of low-grade chondrosarcoma, every chondromatous lesion can be followed-up. Biopsies must be performed based on clinical and radiological suspicions such as pain, scalloping or increase in size, rather than on performing a PET scan to evidence more informative high metabolic areas.

How to Diagnose Enchondroma, Bone Infarct, and Chondrosarcoma

Enchondromas are among the most common benign tumors seen in the skeleton. They are encountered frequently in routine clinical practice. The purpose of this review is to help radiologists confidently diagnose enchondroma and distinguish it from other entities, such as bone infarct, bone graft, and low-grade chondrosarcoma.

T1-Weighted Dynamic Contrast-Enhanced MR Perfusion Imaging Characterizes Tumor Response to Radiation Therapy in Chordoma

BACKGROUND AND PURPOSE

Chordomas notoriously demonstrate a paucity of changes following radiation therapy on conventional MR imaging. We hypothesized that dynamic contrast-enhanced MR perfusion imaging parameters of chordomas would change significantly following radiation therapy.

MATERIALS AND METHODS

Eleven patients with pathology-proved chordoma who completed dynamic contrast-enhanced MR perfusion imaging pre- and postradiation therapy were enrolled. Quantitative tumor measurements were obtained by 2 attending neuroradiologists. ROIs were used to calculate vascular permeability and plasma volume and generate dynamic contrast-enhancement curves. Quantitative analysis was performed to determine mean and maximum plasma volume and vascular permeability values, while semiquantitative analysis on averaged concentration curves was used to determine the area under the curve. A Mann-Whitney U test at a significance level of P < .05 was used to assess differences of the above parameters between pre- and postradiation therapy.

RESULTS

Plasma volume mean (pretreatment mean = 0.82; posttreatment mean = 0.42), plasma volume maximum (pretreatment mean = 3.56; posttreatment mean = 2.27), and vascular permeability mean (pretreatment mean = 0.046; posttreatment mean = 0.028) in the ROIs significantly decreased after radiation therapy (P < .05); this change thereby demonstrated the potential for assessing tumor response. Area under the curve values also demonstrated significant differences (P < .05).

CONCLUSIONS

Plasma volume and vascular permeability decreased after radiation therapy, suggesting that these dynamic contrast-enhanced MR perfusion parameters may be useful for monitoring chordoma growth and response to radiation therapy. Additionally, the characteristic dynamic MR signal intensity-time curve of chordoma may provide a radiographic means of distinguishing chordoma from other spinal lesions.

Bone marrow perfusion measured with dynamic contrast enhanced magnetic resonance imaging is correlated to body mass index in adults

Bone marrow metabolism is complex and far from being fully understood. Novel aspects, such as the roles of bone marrow adiposity and vascularisation in bone metabolism currently attract attention. There is also a growing interest in the influence obesity might have on bone metabolism. Our objective was to determine the effect of BMI on bone marrow perfusion parameters using dynamic contrast-enhanced magnetic resonance imaging. This prospective monocentric study was approved by our local Ethics committee. Written consent was obtained. The right hip of 59 adults under 60years old (mean age 37.5) was imaged with a dynamic 3D T1 spoiled gradient echo magnetic resonance imaging sequence. Mean BMI was 24.8 (+/-4.4). Perfusion parameters were measured in the acetabulum and femoral neck, in the greater trochanter, in the femoral head epiphysis and in the subcutaneous adipose tissue. Associations between perfusion parameters and BMI were studied using a linear mixed model adjusted for age and sex effects. Our results showed that as the BMI increased, the exchanges between blood and bone marrow appeared more important (increased K_trans and K_ep values, p=0.018 and p=0.002 respectively) and the intramedullary blood flow appeared increased (lower time to peak values, p=0.0002). In the subcutaneous fat, as the BMI increased, the vascularization decreased (lower area under the curve and initial slope values, p=0.019 and p=0.013 respectively). These results suggest that there is a relation between bone marrow perfusion and BMI, and that subcutaneous fat and bone marrow fat have different microvascular behaviours. Researchers must be aware of the effect of BMI on bone marrow perfusion parameters when they build a MR research protocol and analyse their data. A better understanding of these findings may provide the basis for the management of obesity-related bone changes.

Diagnostic value of combined diffusion-weighted imaging with dynamic contrast enhancement MRI in differentiating malignant from benign bone lesions

AIM

To determine the diagnostic value of combined diffusion-weighted imaging (DWI) with dynamic contrast enhancement magnetic resonance imaging (DCE-MRI) in differentiating malignant from benign bone lesions.

MATERIALS AND METHODS

DWI and DCE-MRI were performed in 36 patients (14 were benign and 22 were malignant). The mean apparent diffusion coefficient (ADC) values and signal enhanced extent (SEE), slope value, and time-signal intensity curve (TIC) type were recorded by two observers. Between-group comparison was made using the independent sample t-test and receiver-operating characteristic (ROC) analysis.

RESULTS

There was a significant difference between the mean ADC value of the benign ([1.75±0.50]×10^-3 mm²/s) and malignant ([1.11±0.47]×10^-3 mm²/s) groups (p=0.001). The threshold ADC value of ≤1.10×10^-3 mm²/s resulted in a sensitivity of 77.3%, a specificity of 92.9%, and an accuracy of 85.1%. A type III curve was found in 23 cases (21 malignant and two benign), a type II curve was seen in six cases (one malignant and five benign), and a type I curve in seven cases (all were benign). The SEE and slope values in the benign and malignant groups were 227.96±172.08, 325.60±125.86 (p=0.058); 0.97±0.67%/s, 3.19±3.20%/s (p=0.016), respectively. ROC analysis showed a sensitivity of 95.5%, a specificity of 85.7%, and an accuracy of 90.6% for malignancy, based on a slope cut-off value of >1.46%/s. Combining ADC and slope values resulted in a sensitivity of 100%, a specificity of 85.7%, and an accuracy of 92.9%.

CONCLUSIONS

Both DWI and DCE-MRI showed promising results for differentiating malignant from benign bone lesions. A combination of DWI and DCE-MRI was the most valuable of the three.

[Cartilage tumors : Pathology and radiomorphology]

Primary cartilage-forming tumors of the bone are frequent entities in the daily work of skeletal radiologists. This article describes the correlation of pathology and radiology in cartilage-forming skeletal tumors, in particular, enchondroma, osteochondroma, periosteal chondromas, chondroblastoma and various forms of chondrosarcoma. After reading, the radiologist should be able to deduce the different patterns of cartilage tumors on radiographs, CT, and MRI from the pathological aspects. Differentiation of enchondroma and chondrosarcoma is a frequent diagnostic challenge. Some imaging parameters, e. g., deep cortical scalloping (more than two thirds of the cortical thickness), cortical destruction, or a soft-tissue mass, are features of a sarcoma. Osteochondromas are bony protrusions with a continuous extension of bone marrow from the parent bone, the host cortical bone runs continuously from the osseous surface of the tumor into the shaft of the osteochondroma and the osteochondroma has a cartilage cap. Chondromyxoid fibromas are well-defined lytic and eccentric lesions of the metaphysis of the long bones, with nonspecific MRI findings. Chondroblastomas have a strong predilection for the epiphysis of long tubular bones and develop an intense perifocal bone marrow edema. Dedifferentiated chondrosarcomas are bimorphic lesions with a low-grade chondrogenic component and a high-grade noncartilaginous component. Most chondrogenic tumors have a predilection with regard to site and age at manifestation.