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Dynamic susceptibility contrast perfusion MR imaging in distinguishing malignant from benign soft tissue tumors in limbs: A pilot study
Yitong Bian1, Guohong Jin2, Yanliang Wang3, Gang Niu1, and Jian Yang1

1Fisrt Affiliated Hospital of Xi'an Jiaotong University, Xian, People's Republic of China, 2General Affiliated Hospital of Ningxia Medical University, Yinchuan, People's Republic of China, 3Luoyang Central Hospital Affiliated to Zhengzhou University

Synopsis

Precise differential and qualitative diagnoses for extremities soft tissue tumors(STTs) are of vital importance. Dynamic susceptibility contrast perfusion MRI(DSC-MRI) enables assessment of overall tumor vascularity, allowing indirect evaluation of the biological aggressiveness of tumors. Therefore, this study aims to discuss the feasibility of DSC-MRI to preliminarily assess in the differentiation between benign and malignant extremities STTs. Our results showed that DSC-MRI might be a non-invasive imaging technique that can play a role in identifying malignant and benign STTs in limbs and provide reliably pathological or physiological information for clinic.

Introduction

Soft tissue tumors(STTs), with low incidence and diagnose rate, are characterized with wide variety and heterogeneity. Therefore, precise differential and qualitative diagnoses are of vital importance for tumor’s treatment strategies and prognosis. The morphology of STTs in regular magnetic resonance imaging(MRI) cannot be distinguished qualitatively between benign and malignant lesions. While the dynamic susceptibility contrast MRI(DSC-MRI), an intravenously administered bolus of contrast agent passes through the intravascular space, which creates local magnetic susceptibility (T2*) effects resulting in signal drop during the first pass of the contrast agent. Studies have showed that DSC-MRI enables assessment of overall tumor vascularity, allowing indirect evaluation of the biological aggressiveness of tumors. To our knowledge, the predictive value of DSC-MRI in patients with STTs has not been investigated yet. Therefore, this study aims to discuss whether DSC-MRI can be used as a biomarker to preliminarily assess the feasibility of DSC-MRI in the differentiation between benign and malignant STTs, and to analyze the best judgement of perfusion parameters.

Methods

A prospective study was done among 33 patients (16 males and 17 females) with STTs in limbs who underwent DSC T2*-weighted perfusion MRI after bolus infusion of gadolinium-DTPA. The signal intensity time curve of the lesion was created and several certain semi-quantitative parameters were analyzed, including negative enhancement integral(NEI)，maximum slope of decrease(MSD), maximum slope of increase(MSI), and mean time to enhance(MTE).NEI represents the relative vascular volume (rBV) of organizational unit volume, MSD and MSI represents respectively TIC maximum signal loss during the descending and ascending scanning segment, which is on behalf of micro-circulatory relative blood flow (rBF). MTE represents the time that the contrast agents go through the organization, which reflect the vascular resistance.Discriminant analyses were performed to reveal parametric differences of benign and malignant lesions. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic efficiency of parameters. All statistical analysis were performed by using SPSS 17.0 (SPSS, Chicago, IL, USA); p<0.05 was considered as statistically significant difference.

Results

Diagnosis of benign (N=13) tumors were Hemangioma(n=4), Lipoma(n=4), Neurilemmoma(n=1), Neurofibroma(n=1), Non-ossifying fibroma(n=2), Giant cell tumor of tendon sheath granuloma(n=1), whereas malignant lesions (N=20) were classified as Liposarcoma(n=5), Fibrosarcoma(n=5), Undifferentiated pleomorphie sarcoma(n=2), Malignant myofibroblastoma(n=1), Malignant melanoma(n=2), Non-Hodgkin lymphoma(n=2), Synovial sarcoma(n=2), Alveolar soft part sarcoma(n=1). Several parameters of perfusion (NEI, MSD, MSI) were significant differences between benign and malignant tumors. But MTE parameter was no significant difference in terms of statistics. The area under the curve (AUC) of NEI, MSD, MSI was 0.915, 0.862, 0.815 respectively. The diagnostic efficiency of NEI was highest for differentiating benign from malignancy in STTs and the sensitivity, specificity, accuracy and positive/negative predictive value(PPV/NPV) were 100%,84.6%,93.9%,90.9% and 100% respectively.

Discussion

In our study, we used this method by analyzing the signal intensity variations in order to create colorimetric maps, without adopting the arterial input. ROIs placement was basically designed on the enhanced substantial component of tumor’s edge according to the theory of different enhancement of edge and center, which reflected the turevascularization of tumor and avoid ingnecrosis, cystic and hemorrhage. Our results showed that there were significant differences between benign and malignant groups in NEI, MSD and MSI. The reason is that malignant tumor has a high micro-vessel density, the abnormality of cell structure and the incomplete basement, it results in a higher blood flow of microcirculation, higher relative blood volume compared the benign tumor. The MTE performance of benign and malignant tumors had overlap and no significant difference. It illustrates that the enhanced time of tumor has no relationship with perfusion of contrast agent. MTE cannot be applied in the diagnosis of benign and malignant tumors. However, the reliability of parameters in evaluating the tumor microcirculation needs further study.

Conclusion

DSC-MRI might be a non-invasive imaging technique that can play a role in identifying malignant and benign STTs in limbs and provide reliably pathological or physiological information for clinic.

Acknowledgements

No acknowledgement found.

References

1. Noebauer-Huhmann, I.M., et al., Use of diagnostic dynamic contrast-enhanced (DCE)-MRI for targeting of soft tissue tumour biopsies at 3T: preliminary results. Eur Radiol, 2015. 25(7): p. 2041-8.

2. Oliveira, A.M. and A.G. Nascimento, Grading in soft tissue tumors: principles and problems. Skeletal Radiol, 2001. 30(10): p. 543-59.

3. Drape, J.L., Advances in magnetic resonance imaging of musculoskeletal tumours. Orthop Traumatol Surg Res, 2013. 99(1 Suppl): p. S115-23.

4. Nguyen, T.B., et al., Comparison of the Diagnostic Accuracy of DSC- and Dynamic Contrast-Enhanced MRI in the Preoperative Grading of Astrocytomas. AJNR Am J Neuroradiol, 2015. 36(11): p. 2017-22.

Figures

Note:STTs, soft tissue tumors; F, female; M, male; D, diameter.

Note: [ ] data presented as ranges;p value <0.05 calculated with Mann-Whitney test indicated a statistically significant difference.

A 59-year-old man with histologically proved liposarcoma. The T2 image (A) showed a heterogeneous mass in the right thigh. The T1 STIR enhancement image (B) showed the mass had an obviously inhomogeneous enhancement, the necrosis and cystic can be seen. The NEI image (C) showed the lesion had a rich blood and high perfusion. The MSD and MSI images (D,E) showed the perfusion of the lesion was higher than the surrounding tissues and the necrosis had no perfusion.The MTE image (F) showed the lesion had no difference with surrounding tissues.

A 27-year-old man with histologically proved schwannoma.The T2 image (A) showed a high signal mass in the leftelbow. The T1 STIR enhancement image (B) showed the mass had an inhomogeneous enhancement, the necrosis and cystic can be seen. The NEI image (C) showed a low perfusion. The MSD and MSI images (D,E) showed the perfusion of the lesion was higher than the surrounding tissues. The MTE image (D) showed the lesion had no difference with surrounding tissues.

Proc. Intl. Soc. Mag. Reson. Med. 25 (2017)
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