Hounsfield unit change in metastatic abdominal lymph nodes treated with combined hyperthermia and radiotherapy.

Objective: Hyperthermia has been safely employed in conjunction with low to moderate doses of radiotherapy (RT) to achieve notable tumor responses in cases of previously treated and recurrent malignancies. However, the radiologic monitoring of combined hyperthermia and RT (HTRT) is not extensively documented. This study aimed to assess radiological changes, including alterations in Hounsfield units (HU), in patients undergoing treatment with either HTRT or RT alone for metastatic abdominal lymph nodes.

Methods: CT images were acquired from consecutive 40 patients who received HTRT or RT alone for metastatic abdominal lymph nodes. Target regions were delineated and pre- and post-treatment HU measurements were extracted from these targets. An additional independent t-test was performed to compare the change in mean HU values between the two groups.

Results: The study included 40 patients, 20 patients in the HTRT group and 20 in the RT alone group. In the HTRT group, the average HU after treatment was 58.95 HU, while in the RT-only group, it was 71.42 HU. In the HTRT-treated group, the average HU value of the tumor was lower by 9.05%, with an average of -8.47 HU. (p =  0.011), while in the RT-only treated group, it declined by 0.57% with an average of -0.41 HU.

Conclusion: The HTRT group showed a greater decrease in HU both pre- and post-treatment, indicating a possible indirect marker of tumor necrosis. Sequential trends and survival analyses for comparing the two groups are warranted in subsequent investigations.