Amide proton transfer-weighted magnetic resonance image-guided stereotactic biopsy in patients with newly diagnosed gliomas

Abstract

Purpose Pathological assessment using WHO criteria is the gold standard for diagnosis of gliomas. However, the accuracy of diagnosis is limited by tissue sampling, particularly for infiltrating, heterogeneous tumors. We assessed the accuracy of amide proton transfer-weighted (APTw) MRI-guided tissue sampling to identify regions of high-grade glioma via radiographic-histopathologic correlation in patients with newly suspected glioma. Patients and methods Twenty-four patients with previously undiagnosed gliomas underwent a volumetric APTw MRI prior to their first neurosurgical procedure. A total of 70 specimens were collected via APTw image-directed stereotactic biopsy. Cellularity, necrosis, proliferation, and glioma WHO grade were analyzed for all specimens and correlated with corresponding APTw signal intensities. Results Thirty-three specimens displayed grade-II pathology, 14 grade-III, 15 grade-IV, and eight specimens revealed only peritumoral edema. Multiple glioma grades were found within a single lesion in six patients. APTw signal intensities of the biopsied sites and the maximum APTw values across all biopsied sites in each patient were significantly higher for high-grade versus low-grade specimens. APTw signal intensities were significantly positively correlated with cellularity (R = 0.757) and proliferation (R = 0.538). Multiple linear regression analysis showed that tumor cellularity and proliferation index were the best predictors of APTw signal intensities. Conclusion APTw imaging identified tumor areas of higher cellularity and proliferation, allowing identification of high-grade regions within heterogeneous gliomas. APTw imaging can be readily translated for more widespread use and assist diagnostic neurosurgical procedures by increasing the accuracy of tumor sampling in patients with infiltrating gliomas

Diagnostic performance of multiparametric MRI in the evaluation of treatment response in glioma patients at 3T

“…Their use for the evaluation of treatment response may be investigated in the future. Nevertheless, the conventional MTR asymmetry analysis has been demonstrated to be applicable in many clinical applications, including tumor identification, glioma grading, treatment response evaluation, and so on, with its feasibility well validated by biopsy or histology . Additionally, it has been demonstrated that the APTw image contrast in the tumor is mostly attributable to the APT contribution under similar RF powers as used here .…”

APT‐weighted MRI: Techniques, current neuro applications, and challenging issues

“…Therefore, it is an important feature that, in cases with high‐grade gliomas without gadolinium enhancement, APTw‐hyperintense foci are still clearly visible within the lesions . Notably, a recent study using APTw image‐guided stereotactic biopsy by Jiang et al suggests that APTw imaging can identify high‐grade regions within heterogeneous gliomas, allowing more precise sampling of the highest‐grade region of a tumor. On the other hand, in patients with pathologically confirmed low‐grade gliomas, including those with gadolinium enhancement, APTw imaging shows isointensity or scattered punctate hyperintensity within the lesion.…”

“…Figures show some examples of these parameters in a human study at 3 T, confirming the minimizing of normal tissue and edema signal into the background and a strong tumor contrast. These saturation parameters were also used in the validation studies with APTw MRI‐directed biopsies . For other applications, the optimal parameters and analysis approaches are still under development.…”

“…Thus, areas of large liquefactive necrosis, hemorrhage, or large vessels would typically demonstrate high APTw signals . It is particularly important to note the inconsistency of APTw signal intensities of coagulative necrosis and liquefactive necrosis in the central regions of malignant gliomas, as identified by T 2 w and FLAIR images . Coagulative necrosis is characterized by the formation of a gelatinous (gel‐like) substance in dead tissues.…”

Fast 3D chemical exchange saturation transfer imaging with variably‐accelerated sensitivity encoding (vSENSE)

“…The CEST method can enhance the detection sensitivity of low‐concentration metabolites in vivo when repeated saturation transfer allows for an accumulation and amplification of the MRI signals derived from metabolite‐specific solute pools. Biomolecules that are detectable by various CEST techniques include polypeptides using amide proton transfer (APT), glycogen with “glycoCEST,” glycosaminoglycan by “gagCEST,” glutamate by “GluCEST,” glucose by “glucoCEST,” and creatine by “CrCEST.” Indeed, CEST MRI has been applied in patients with brain tumors, prostate cancer, breast cancer, and stroke using APT, osteoarthritis using gagCEST, epilepsy using GluCEST, and brain tumors using glucoCEST . Despite its great promise, the clinical use of CEST MRI is limited by the long acquisition times needed to acquire multiple frames at different saturation offset frequencies, and for quantification …”