Chest and Oncology

Discussion

25-year-old male with Hodgkin’s lymphoma in remission, annual follow-up CT.

Help to evaluate the viability of a mediastinal mass in Hodgkin’s lymphoma in a patient in remission and help to monitor response to therapy.

Axial and coronal images

Conventional follow-up CT scan with contrast demonstrated an anterior mediastinal mass with calcifications, stable in size compared to previous CT examinations. Iodine density and Z effective images showed lack of iodine within the lesion indicative of nonviable/ fibrous residue rather than recurrence. Virtual non-contrast images demonstrated calcification within the mass and attenuation value of the mass (57.3 HU) similar to contrast enhanced images (57.2 HU and 59.8 HU). PET/CT at initial diagnosis, which took place 2.5 years prior, showed high metabolic activity within the enlarged mediastinal mass. After chemotherapy and radiotherapy, PET/CT performed one year later demonstrated significant decrease in size and lack of metabolic activity within the lesion, indicating good response to treatment.

Iodine density and Z effective spectral images may help to evaluate the viability of a mass seen on follow-up CT imaging in lymphoma patients and help to differentiate residual nonviable/fibrous mass from recurrence. Dual-energy CT could have a role in monitoring response to therapy and follow up in lymphoma patients with comparable images to PET/CT.

Conventional CT coronal image, mediastinal window: anterior mediastinal mass with attenuation value of 59.8 HU (arrow).

Virtual non-contrast image: attenuation value of the mass is 57.3 HU and similar to contrast enhanced images (59.8 HU).

Iodine density image: iodine density within the mass (0.42 mg/ml) is below threshold (0.5 mg/ml).

Z effective image: mass shown without iodine content is color coded in yellow.