MRI and proton-NMR relaxation times in diagnosis and therapeutic monitoring of squamous cell carcinoma

Abstract

The potential application of MRI and proton nuclear magnetic resonance (NMR) relaxation times to predict tumor growth and tumor response to therapy is investigated in 91 patients with various head and neck tumors. Of the 91 patients 38 underwent surgery and 53 underwent combined modality treatment (radiochemotherapy; RCT). The MRI morphology parameters and proton-NMR relaxation times before, during, and after therapy were evaluated. The spin-lattice T1 relaxation time of squamous cell carcinoma (SCC) primary tumors is 815 ±128 ms. The following is the SCC primary tumor's behavior during therapy: Following the first RCT course 21 patients showed a complete tumor remission by volumetric morphological, and relaxometric parameters due to normalization; 32 patients showed a significant reduction in T1 relaxation time in the primary SCC tumor region (712 ± 117 ms); 19 showed residual tumors and 13 showed reactive inflammation in biopsy. In 24 cases a morphological normalization was determined following the second RCT course; in 29 cases MR morphology showed residual signal-intensity pathology and an elevation of T1-time values (787 ± 139 ms), but histology verified residual tumors in only 6 of these patients. Reactive edema and inflammation overlies MRI's morphology and relaxometry parameters in further controls. The histological verification shows a spin-lattice T1 relaxation time of 549 ± 181 ms for hyperplastic lymph nodes, 924 ± 116 ms for malignant SCC lymph nodes, and 854 ± 23 ms for inflammation. The sensitivity of the spin lattice relaxation time is 82%, and the specificity is 93%. The negative predictive value is 85% and the positive predictive value is 93%. The T1 relaxation time of hypothetical malignant lymph nodes changes during combined modality treatment: Following the first RCT course in residual lymph nodes the spin-lattice relaxation time is reduced significantly (P < 0.01; T1 = 785 ± 116 ms). After the second course the reduction is more pronounced (P < 0.01; T1 = 731 ± 71 ms), reaching values of hyperplastic lymph nodes expressing a normalization. We conclude that the spin-lattice relaxation time improves lymph nodes classification, and the T1 relaxation time is useful as a predictive assay indicating favorable therapeutic changes.