Both a visual and a semiquantitative analysis for differentiating benign from malignant chondrogenic bone tumors using Tc-99m (V) DMSA scintigraphy: a prospective study

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.].

Preliminary clinical assessment of dynamic carbon-11 methionine positron-emission tomography/computed tomography for the diagnosis of the pathologies in patients with musculoskeletal lesions: a prospective study

Background

This study prospectively assessed the diagnostic capacity of dynamic carbon-11 methionine (C-11 MET) positron-emission tomography (PET)/computed tomography for the diagnosis of pathologies in patients with primary unknown musculoskeletal lesions (MSLs). In total, 13 patients with MSLs underwent dynamic scans (5–10 [phase 1], 10–15 [phase 2], 15–20 [phase 3], 20–25 [phase 4], 25–30 [phase 5], and 30–35 [phase 6] min post-injection of C-11 MET). We statistically compared the maximum standardised uptake values (SUVmax) and corresponding retention index for dynamic scans (RI-SUV) for five benign MSLs (BMSLs), five primary malignant musculoskeletal tumours (PMMSTs), four metastatic musculoskeletal tumours (MMSTs), and three malignant lymphoma (ML) cases and explored their diagnostic capacities using receiver operating characteristic (ROC) curve analyses.

Results

SUVmax gradually decreased or remained similar with minimal fluctuations in all BMSL cases and four of five PMMST cases. In contrast, SUVmax increased over time in one case of PMMST and in all cases of MMST and ML. Significant differences were observed in SUVmax for all time phases and RI-SUV between BMSLs and MMSLs, in SUVmax for all time phases between PMMSTs and BMSLs, in SUVmax for all time phases and RI-SUV between non-PMMST-malignant tumours and BMSL, and in RI-SUV between non-PMMST-malignant tumours and PMMST. In ROC analyses, the areas under the curve yielded the highest values at 1.00 for differentiating most intergroup comparisons.

Conclusions

Dynamic C-11 MET PET scans have the potential to be good predictors of discriminating MSLs in patients with primary unknown MSLs in clinical practice.

Simplified dual time point FDG-PET/computed tomography for determining dignity of pancreatic lesions

BACKGROUND

Predicting the dignity of pancreatic lesions is still a diagnostic challenge. The differentiation between benign changes in chronic pancreatitis from pancreatic cancer remains difficult. Therefore, the aim of this study was to evaluate whether early dual time point kinetics of pancreatic lesions in 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) may be helpful to differentiate pancreatic lesions.

METHODS

We prospectively analyzed 64 patients (pancreatic cancer n = 45 and chronic pancreatitis n = 19) scheduled for dual time point FDG-PET/computed tomography scan for pancreatic lesions from 2005 to 2014. Studies were performed 60 and 90 minutes after application of F-FDG. Histological samples were collected for all patients, either by resection or by biopsy. Semiquantitative analysis was performed using the minimum, the maximum, and the average standardized uptake value (SUV) from the two different sets of images. To increase sensitivity and specificity, a formula addressing the weighting of standardized uptake values was created.

RESULTS

With a sensitivity of 82.6%, specificity of 77.8%, accuracy of 79.7%, positive predictive value of 90.5%, and negative predictive value of 63.6% SUVmax@time1 > 3.45 was the most reliable single quantitative parameter for malignancy of the pancreatic lesions. Weighting of standardized uptake values produced a formula that showed an even better profile.

CONCLUSIONS

In patients with suspicious pancreatic lesions, the simplified dual time point FDG-PET/computed tomography may represent a valuable diagnostic tool in characterizing pancreatic lesions.

The role of Thallium-201 scintigraphy and Tc-99m pentavalent dimercaptosuccinic acid in diagnosis and grading of chondrosarcoma

PURPOSE

Distinguishing between enchondromas and low-grade (grade 1) chondrosarcomas can be challenging. The aim of this study was to investigate the role of Thallium-201 scintigraphy and Technetium-99 m pentavalent dimercaptosuccinic acid (Tc-99 m DMSA (V)) in the diagnosis and grading of chondrosarcomas.

METHODS

232 consecutive patients with pathologically proven cartilaginous tumours between the years 2000 and 2018 were evaluated. We included 197 patients (101 males and 96 females; median age 50 years; range 15-86 years) who underwent Thallium-201(n = 193) and/or Tc-99 m DMSA (V) scanning (n = 67). Increased uptake was defined as uptake greater than background. The reference standard was the histopathological assessment based on a grading system (grade 1-3). Data was analysed using multivariate modelling.

RESULTS

There were 46 patients with enchondromas and 151 with chondrosarcomas. Of those, 64 (enchondroma n = 21, chondrosarcoma n = 43) underwent both Thallium-201 and Tc-99 m DMSA (V). Thallium-201 uptake had 7.92 times greater odds of grade 1 chondrosarcomas than enchondromas. Thallium-201 uptake was significantly associated with the odds of a higher grade chondrosarcoma (grade 2-3). DMSA (V) positivity was associated with 4.75 times the odds of a chondrosarcoma diagnosis over enchondroma (p = 0.024). DMSA (V) uptake revealed no association with chondrosarcoma grading.

CONCLUSION

Low-grade chondrosarcomas continue to pose a diagnostic dilemma. Thallium-201 scans may identify malignancy in benign appearing tumours as well as differentiate between low-grade and high-grade chondrosarcomas in said malignancies. DMSA (V) may be useful in distinguishing between benign and malignant entities as a whole.

Diagnostic accuracy of functional imaging modalities for chondrosarcoma: A systematic review and meta-analysis

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Functional imaging modalities may have an important role in diagnosing chondrosarcomas.

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PET is a sensitive and specific test for differentiating chondrosarcomas and benign chondroid tumours.

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Thallium-201 scintigraphy has a high positive predictive value for chondrosarcomas.

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DMSA (V) has a 100% negative predictive value and can be used to rule out chondrosarcomas.

Introduction

The distinction between low-grade (grade 1) chondrosarcoma and its benign counterparts can be challenging. This systematic review aims to quantify the diagnostic accuracies of all functional imaging modalities used in the diagnosis of chondrosarcoma.

Methods

Medline and Embase were searched in February 2019. We included studies of either retrospective or prospective design if the results of functional scans were compared with pre-determined reference standards. Studies had to be primary diagnostic reports on patients with chondral tumours at first diagnosis. Two review authors independently performed study selection, extracted data and assessed the methodological quality. We calculated diagnostic accuracy measures for each included study.

Results

Four functional imaging modalities were identified across thirteen studies that met the inclusion criteria. 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) was a sensitive and specific test. Technetium-99 m with methylene diphosphonate (Tc-99 m MDP) had an overall low specificity of 4%. Thallium-201 scintigraphy demonstrated high positive predictive values across the studies. The negative predictive values of Technetium-99 m pentavalent dimercaptosuccinic acid (Tc-99 m DMSA (V)) were consistently 100%.

Conclusions

Low-grade chondrosarcomas continue to pose a diagnostic dilemma. FDG-PET demonstrated superior diagnostic accuracy compared to Tc-99 m MDP, Thallium-201 and Tc-99 m DMSA (V). Characteristic uptake patterns of Thallium-201 and Tc-99 m DMSA (V) may provide additional metabolic information to guide the diagnosis in this challenging group of tumours.