Photon counting computed tomography in head and neck squamous cell carcinoma: iodine concentration and...

Head and neck squamous cell carcinoma (HNSCC) is a common malignancy with increasing relevance in oncologic imaging. Photon-counting computed tomography (PCCT) allows for quantitative assessment in iodine concentration (IC) offering new insights into tumor biology. This study aimed to investigate the association between normalized IC (NIC) and histopathological features in HNSCC.

Eighty-four patients with primary untreated HNSCC underwent contrast-enhanced PCCT of the neck in venous phase. Iodine maps were generated to quantify intratumoral IC. NIC was calculated as the ratio of tumoral IC to aortal IC. Histopathological analysis included tumor stage, tumor grade, Ki 67 proliferation index, tumor cell count and human papillomavirus (HPV) status. Group comparison were conducted using Mann-Whitney-U tests. Interreader agreement was assessed via intraclass correlation coefficient (ICC). Receiver operating characteristic (ROC) analysis was performed to evaluate diagnostic performance of NIC for HPV status.

NIC values demonstrated excellent interreader reliability (ICC = 0.96, 95%CI = (0.92; 0.98), p < 0.01). NIC showed an inverse correlation with tumoral cell count (r = -0.24, p = 0.03). Tumors with lymphonodal metastases exhibited lower NIC values compared to N0 tumors (0.42 ± 0.20 vs. 0.54 ± 0.26, p = 0.02). Cell-rich tumors had lower NIC values than cell-poor tumors (0.42 ± 0.18 vs. 0.53 ± 0.26, p = 0.003). HPV negative tumors showed higher NIC values than HPV-positive tumors (0.51 ± 0.23 vs. 0.33 ± 0.18, respectively, p < 0.01). A NIC threshold of ≥ 0.5 predicted HPV negative tumors, demonstrating 54.5% sensitivity and 94.4% specificity, with an AUC of 0.74 (95% CI = 0.62-0.86, p < 0.01).

NIC derived from PCCT is a robust and reproducible imaging parameter in HSNCC. It is moderately associated with tumor cellularity, nodal involvement, and HPV status. Thus, NIC may serve as a valuable adjunct in non-invasive tumor characterization.