Date Published: April 24, 2019
Publisher: Public Library of Science
Author(s): Jitender Saini, Rakesh Kumar Gupta, Manoj Kumar, Anup Singh, Indrajit Saha, Vani Santosh, Manish Beniwal, Thennarasu Kandavel, Marc Van Cauteren, Quan Jiang.
To assess the inter-technique agreement of relative cerebral blood volume (rCBV) measurements obtained using T1- and T2*-perfusion MRI on 3T scanner in glioma patients.
A total of 49 adult patients with gliomas underwent both on T1- and T2*-perfusion in the same scanning session, and rCBV maps were estimated using both methods. For the quantitative analysis; Two independent observers recorded the rCBV values from the tumor as well as contralateral brain tissue from both T1- and T2*-perfusion. Inter-observer and inter-technique rCBV measurement agreement were determined by using 95% Bland-Altman limits of agreement and intra-class correlation coefficient (ICC) statistics.
Qualitative analysis of the conventional and perfusion images showed that 16/49 (32.65%) tumors showed high susceptibility, and in these patients T2*-perfusion maps were suboptimal. Bland-Altman plots revealed an agreement between two independent observers recorded rCBV values for both T1- and T2*-perfusion. The ICC demonstrated strong agreement between rCBV values recorded by two observers for both T2* (ICC = 0.96, p = 0.040) and T1 (ICC = 0.97, p = 0.026) perfusion and similarly, good agreement was noted between rCBV estimated using two methods (ICC = 0.74, P<0.001). ROC analysis showed that rCBV estimated using T1- and T2*-perfusion methods were able to discriminate between grade-III and grade-IV tumors with AUC of 0.723 and 0.767 respectively. Comparison of AUC values of two ROC curves did not show any significant difference. In the current study, T1- and T2*-perfusion showed similar diagnostic performance for discrimination of grade III and grade IV gliomas; however, T1-perfusion was found to be better for the evaluation of tumors with intratumoral hemorrhage, postoperative recurrent tumors, and lesions near skull base. We conclude that T1-perfusion MRI with a single dose of contrast could be used as an alternative to T2*-perfusion to overcome the issues associated with this technique in brain tumors for reliable perfusion quantification.
Perfusion-MRI is used in the daily clinical practice for the evaluation of hemodynamic changes in brain tumors for more than a decade and serves as a surrogate marker for tumor angiogenesis [1,2]. Two most common techniques used for contrast-enhanced perfusion-MRI are; a T2*-based dynamic susceptibility contrast (DSC) perfusion MRI, and T1-based dynamic contrast-enhanced (DCE) MRI. In DCE/T1-perfusion, contrast causes an increase in signal intensity proportional to the tissue contrast concentration, while in DSC/T2*-perfusion, first pass of gadolinium-based contrast material through the vasculature causes signal drop due to the susceptibility effects caused by contrast bolus [3–5]. A relative cerebral blood volume (rCBV) map, which provides a measure of the tumor neovascularization, is the most widely used quantitative hemodynamic perfusion metrics . The rCBV maps serve as an important imaging biomarker and extensively used for brain tumor grading, post-surgical tumor assessment, and treatment response [5,7,8].
A total of 49 patients with supratentorial gliomas were included in this study. All patients were histopathologically confirmed and classified according to the latest WHO classification . Six patients had low-grade lesions; thirty-one had grade-III, and twelve harbored grade-IV tumors (Table 1). Out of 49 cases, there were 6 cases with post-surgery tumor recurrence.
In this study, we compared the rCBV values derived independently using T1- and T2*-perfusion MRI in the patients with gliomas, and both techniques showed a good agreement with the comparable diagnostic performance for the discrimination of grade III and grade IV glioma. T2*-perfusion data was suboptimal in 32.63% of the patients due to the presence of significant intratumoral susceptibility arising from blood products, adjacent bone or sinuses in case of tumors located near to the skull base or post-surgical changes; on the other hand, all these tumors could be evaluated entirely by using T1-perfusion MRI.
We conclude that T1-perfusion with a single dose of contrast could be used as an alternative to T2*-perfusion to overcome the issues associated with this technique in brain tumors for reliable perfusion quantification. This is especially true for hemorrhagic, and post-treatment follow-up cases of gliomas.