Author: Sandeep Panwar Jogi, Nancy Lee, Ricardo Otazo, Ramesh Paudyal, Qi Peng, Akash Shah, Amita Shukla-Dave, Can Wu 👨🔬
Affiliation: Department of Radiology, Memorial Sloan Kettering Cancer Center, Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, Department of Medical Physics, Memorial Sloan Kettering Cancer Center, Department of Radiology, Albert Einstein College of Medicine and Montefiore Medical Center 🌍
Purpose: Quantitative T1ρ imaging provides enhanced tissue characterization beyond standard T1 and T2 parameters, potentially supporting early-stage longitudinal monitoring of head and neck cancer. This study aimed to evaluate the test-retest repeatability of quantitative 3D T1ρ imaging for head and neck squamous cell carcinoma (HNSCC) to establish its clinical utility.
Methods: Ten HNSCC patients undergoing radiotherapy consented to this IRB-approved study. Fifteen test-retest data pairs were acquired using a 3D T1ρ imaging sequence on a 3.0T MRI (Philips Healthcare) with a 16-channel head-and-neck coil. Eight data sets were collected before treatment and seven during the second week of radiotherapy. Each test-retest scan included a 10-minute interval, during which patients were removed from the table for rest and then repositioned for the second scan. T1ρ maps were generated offline using mono-exponential fitting. An expert radiologist delineated regions of interest (ROIs) for primary tumors (PT), metastatic lymph nodes (MLN), and contralateral muscles (CM) to evaluate T1ρ values. Repeatability was assessed using intra-class correlation coefficients (ICCs), within-subject coefficients of variation (wCoVs), repeatability coefficients (RCs), and Bland-Altman analysis (bias and 95% confidence interval) for each ROI.
Results: The ICCs for T1ρ values were 0.92 for PT, 0.97 for MLN, and 0.68 for CM. The mean wCoVs were 5.54% for PT, 2.42% for MLN, and 3.71% for CM. The mean RCs were 14.88 ms for PT, 7.07 ms for MLN, and 5.37 ms for CM. Bland-Altman analysis revealed biases (-1.96 SD, 1.96 SD) of -5.89 ms (-20.11 ms, 8.33 ms) for PT, -1.31 ms (-9.80 ms, 7.17 ms) for MLN, and 0.31 ms (-7.21 ms, 7.84 ms) for CM.
Conclusion: This study demonstrated high repeatability of T1ρ values for primary tumors, metastatic lymph nodes, and contralateral muscles. These findings highlight the potential of quantitative 3D T1ρ imaging for longitudinal monitoring of head and neck cancer.