NI-15 Comparison of amide proton transfer imaging with perfusion imaging of using arterial spin-labeling for evidence of tumor cells in glioma

BACKGROUND: Infiltrative gliomas show cerebral edema and tumor infiltration as areas of hyperintensity in FLAIR image. Amide proton transfer (APT) and cerebral blood flow (CBF) are useful for evaluating the tumor invasion. In this study, arterial spin-labeling (ASL)-CBF and APT were compared to determine which method was superior for predicting tumor infiltration in gliomas, pathologically. METHODS: Fifteen specimens from 5 glioma patients with confirmed selective sampling were obtained. Based on APT signal intensity (SI), regions of interests (ROIs) were selected for biopsy. Same regions of these ROIs were marked on the same slice of ASL imaging. Samples were pathologically assessed for cell density and vessel density. APT SI and ASL-CBF were analyzed for each specimen. RESULTS: APT signal intensity (SI) showed a strong correlation with cell density (R = 0.887, P < 0.0001). ASL-CBF showed no correlation with cell density (R = 0.240; P = 0.3836) but a correlation with vessel density (R = 0.697; P = 0.0038). In linear regression analysis, APT SI showed a positive relationship with cell density (R2 = 0.787, P < 0.0001, linear regression; y = 30.70 + 6.24E-3*x). CONCLUSIONS: APT imaging was superior in predicting cellular proliferation than ASL-CBF and a powerful predictor of cell density. APT imaging allowed revelation of novel clues reflecting tumor proliferation in brain tumor; to date, this is the first known report to assess cell density among various brain tumors and conditions after treatment.

Amide proton transfer imaging in differentiation of type II and type I endometrial carcinoma: a pilot study

Purpose This study aimed at evaluating the efficacy of amide proton transfer (APT) imaging in differentiation of type II and type I uterine endometrial carcinoma. Materials and methods Thirty-three patients diagnosed with uterine endometrial carcinoma, including 24 with type I and 9 with type II carcinomas, underwent APT imaging. Two readers evaluated the magnetization transfer ratio at 3.5 ppm [MTRasym (3.5 ppm)] in each type of carcinoma. The average MTRasym (APTmean) and the maximum MTRasym (APTmax) were analyzed. The receiver operating characteristic (ROC) curve analysis was performed. Results The APTmax was significantly higher in type II carcinomas than in type I carcinomas (reader1, p = 0.004; reader 2, p = 0.014; respectively). However, APTmean showed no significant difference between type I and II carcinomas. Based on the results reported by reader 1, the area under the curve (AUC) pertaining to the APTmax for distinguishing type I from type II carcinomas was 0.826, with a cut-off, sensitivity, and specificity of 9.90%, 66.7%, and 91.3%, respectively. Moreover, based on the results reported by reader 2, the AUC was 0.750, with a cut-off, sensitivity, and specificity of 9.80%, 62.5%, and 87.5%, respectively. Conclusion APT imaging has the potential to determine the type of endometrial cancer.

Comparison of Diffusion Kurtosis Imaging and Amide Proton Transfer Imaging in the Diagnosis and Risk Assessment of Prostate Cancer

ObjectivesThis study aims to evaluate and compare the diagnostic value of DKI and APT in prostate cancer (PCa), and their correlation with Gleason Score (GS).Materials and MethodsDKI and APT imaging of 49 patients with PCa and 51 patients with benign prostatic hyperplasia (BPH) were collected and analyzed, respectively. According to the GS, the patients with PCa were divided into high-risk, intermediate-risk and low-risk groups. The mean kurtosis (MK), mean diffusion (MD) and magnetization transfer ratio asymmetry (MTRasym, 3.5 ppm) values among PCa, BPH, and different GS groups of PCa were compared and analyzed respectively. The diagnostic accuracy of each parameter was evaluated by using the receiver operating characteristic (ROC) curve. The correlation between each parameter and GS was analyzed by using Spearman’s rank correlation.ResultsThe MK and MTRasym (3.5 ppm) values were significantly higher in PCa group than in BPH group, while the MD value was significantly lower than in BPH group. The differences of MK/MD/MTRasym (3.5 ppm) between any two of the low-risk, intermediate-risk, and high-risk groups were all statistically significant (p <0.05). The MK value showed the highest diagnostic accuracy in differentiating PCa and BPH, BPH and low-risk, low-risk and intermediate-risk, intermediate-risk and high-risk (AUC = 0.965, 0.882, 0.839, 0.836). The MK/MD/MTRasym (3.ppm) values showed good and moderate correlation with GS (r = 0.844, −0.811, 0.640, p <0.05), respectively.ConclusionDKI and APT imaging are valuable in the diagnosis of PCa and demonstrate strong correlation with GS, which has great significance in the risk assessment of PCa.

Amide proton transfer MRI can accurately stratify gliomas according to their IDH mutation and 1p/19q co-deletion status.

2561 Background: Amide proton transfer (APT) MRI provides sensitive metrics at the amides and amines offsets from the water resonance and has been shown in small cohorts to differentiate low from high grade gliomas with better diagnostic performance than diffusion- and perfusion-weighted MRI. The purpose of our study was to assess APT-MRI performance to stratify gliomas according to their IDH mutation and 1p/19q status. Methods: Forty-five patients with primary gliomas and diffuse astrocytomas (26 WHO grade II, 11 WHO grade III, 8 WHO grade IV) underwent prospectively multi-parametric MRI with APT imaging at 3T scanner. The molecular classification identified 9 patients with IDH-wildtype, 1p/19q retained and 36 with IDH-mutant (22 had 1p/19q-retained, 14 had 1p/19q-codeleted). Tumour segmentations were manually created and the masks were superimposed on the calculated magnetisation transfer ratio asymmetry (MTRasym) spectra and proton transfer ratio APT maps. Individual and group analysis was conducted to analyse the statistical differences between quantitative imaging parameters for the IDH mutation and 1p/19q codeletion statuses. Results: The MTRasym spectra showed a clear difference between IDH-wildtype and IDH-mutant gliomas, with the IDH-mutant gliomas presenting a stronger contribution in the amines (p < 0.001). In IDH-mutant 1p/19q-retained and IDH-mutant 1p/19q-codeleted, the MTRasym spectra showed similarities in shape with higher intensity (approx. 60%) for the IDH-mutant 1p/19q-retained gliomas over the entire spectrum indicating an increased content in amines and amides in IDH-mutant 1p/19q-retained (p < 0.01). Notably, the latter entities showed higher amides levels than the IDH-wildtype gliomas (p < 0.03). Conclusions: APT-MRI shows a remarkable potential to disentangle the protein metabolism in gliomas, to link metabolic patterns to the IDH and 1p/19q status and hence provide robust surrogate biomarkers for non-invasive histomolecular classification with potential use as treatment monitoring tools.

NI-10 AVAILABILITY OF AMIDE PROTON TRANSFER-WEIGHTED MRI METRICS IN GLIOMA

OBJECTIVE Chemical exchange saturation transfer (CEST) is a novel MR imaging contrast technique that relies on the molecular characteristics of the sample. Amide proton transfer (APT) imaging is an emerging CEST-based MR imaging technique that is sensitive to mobile proteins and peptides in the tissue. APT imaging has become increasingly recognized as a promising imaging modality for glioma. Several reports suggest that APT signals are a promising imaging biomarker for glioma grading and prediction of molecular marker status. In this study, we assessed the utility of APT imaging in glioma by evaluating the relationship between APT signals and clinical parameters in glioma. METHODS We enrolled 23 glioma patients (25 lesions) who underwent preoperative MRI with APT imaging and surgery at our institution between May 2018 and July 2019. The median age of patients was 64 years old (range, 14–84). 2 patients had Grade 2, 1 patient had Grade 3, and 22 patients had Grade 4. APT signals were measured inside the ROI that was manually placed in the solid portion of tumor that best represented the entire tumor signal on raw APT images. RESULTS We could see that the high APT signals seemed to be related to IDH wild status and high glioma grading (IDH status; p=0.171, Grade; p=0.113). Moreover, the high APT signals were significantly strong related to high Mib-1 LI (p=0.0068, cutoff: 3.295%, sensitivity: 83%, specificity: 71%). CONCLUSIONS APT imaging might be associated with IDH mutation status and glioma grading. Especially, high APT signal was a great predictor of high MIB-1 LI in glioma.