# CT-like MR images to assess changes after radiotherapy for bone metastasis: a case report

## TL;DR

This case report explores the use of CT-like MRI to assess changes in bone metastasis after radiotherapy, highlighting its potential for monitoring treatment effects.

## Contribution

The study introduces the use of CT-like MRI for evaluating bone metastasis before and after radiotherapy, a previously unexplored application.

## Key findings

- CT-like MRI showed signal changes in bone metastasis 2 months after RT, while T2-weighted MRI and CT showed no changes.
- The study emphasizes the need to examine image changes over time to predict the duration of pain relief from RT.
- Combining CT and MRI modalities may help predict prognosis in bone metastasis patients.

## Abstract

Setting the echo time to zero allows for the acquisition of bone images that were otherwise difficult to obtain with conventional MRI and clear visualization of CT-like MR images. This technique is mainly useful for detecting compression fractures; however, studies examining bone tumours have been lacking. Furthermore, no reports to date have investigated the usefulness of MRI for evaluating images before and after radiotherapy (RT) for bone tumours. Therefore, plain CT and MRI (T1/T2-weighted image and CT-like MRI) were performed under the same conditions before and after radiation therapy (RT) and examined the obtained images. An 86-year-old man received RT (30 Gy/3 fraction) for painful lumbar metastasis from prostate cancer. At 2 months after RT, no changes in T2-weighted images and plain CT scans were noted, but CT-like MRI showed an increase in the signal inside the bone metastasis. Examining how the images change over time is imperative given the difficulty of predicting the duration of the pain relief effects of RT for bone metastases. Therefore, the current case report explored whether combining various modalities, such as CT and MRI, could predict prognosis. We highlight the importance of investigating whether signal changes are correlated with pain symptoms and whether MRI can be a predictor.