A Study of the Correlation of Perfusion Parameters in High-Resolution GRASP MRI With Microvascular Density in Lung Cancer

Background: The histological count of microvascular density (MVD) is the current clinical standard for assessing tumor angiogenesis. Although it is hypothesized that perfusion MRI can be a noninvasive alternative to MVD, there have been few studies to validate their correlations, particularly in lung cancer. Purpose: To investigate the correlation between MVD and perfusion parameters obtained from high-resolution GRASP (Golden-angle RAdial Sparse Parallel) dynamic contrast-enhanced (DCE)-MRI in a cohort of lung cancer patients, and to validate that GRASP MRI can serve as a free-breathing, noninvasive imaging approach for studying tumor angiogenesis. Study Type: Prospective. Population: Twenty-five lung cancer patients (16 male, 9 female, mean age = 57.3 ± 11.7 years). Field Strength/Sequence: 3T MRI; a prototype golden-angle stack-of-stars sequence. Assessment: Contrast-enhanced MR data were acquired during free breathing and were reconstructed using GRASP with a temporal resolution of ∼3 sec/phase. For all data, perfusion analysis was performed using a standard Tofts model to generate the volume transfer coefficient (K ^trans ) and the interstitial volume (V _e ). The MVD of corresponding tumor specimens, obtained from Computed Tomography-guided biopsies, were counted with CD34 staining. Statistical Tests: Pearson correlation analysis; one-way analysis of variance analysis; least significant difference-t method of multiple comparisons. Results: The correlation coefficient was 0.983 and 0.972 for the measurement and remeasurement of K ^trans and V _e . The mean values of K ^trans , V _e , and MVD were 0.33 ± 0.22 min ^-1 , 0.25 ± 0.12, and 49.68 ± 27.08 vessels/0.723 mm ² , respectively, in all patients (n = 25); 0.36 ± 0.26 min ^-1 , 0.27 ± 0.13, and 49.09 ± 29.84 vessels/0.723 mm ² , respectively, in adenocarcinoma (n = 15); 0.34 ± 0.17 min ^-1 , 0.26 ± 0.12, and 53.85 ± 23.53 vessels/0.723 mm ² , respectively, in squamous cell carcinoma (n = 8); and 0.13 ± 0.15 min ^-1 , 0.14 ± 0.06, and 37.20 ± 28.28 vessels/0.723 mm ² , respectively, in small-cell carcinoma (n = 2). There was a positive relationship between the K ^trans and MVD in all patients (r = 0.738, P < 0.001). Data Conclusion: High spatiotemporal resolution DCE-MRI using GRASP is a promising noninvasive alternative to the histological count of MVD for assessing tumor angiogenesis in lung cancer. Level of Evidence: 1. Technical Efficacy: Stage 2. J. Magn. Reson. Imaging 2019;49:1186–1194.