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Published on: February 7, 2025
Early radiation-induced bone marrow injury: serial MR imaging during initial 4 weeks after irradiation
Wencai Huang1, Yiheng Yang, Zhiqiang Sun
1Department of Radiology, Wuhan General Hospital of Guangzhou Command, 627 Wuluolu Ave, Wuhan, Hubei 430070, China. sudahwc@sina.com
Rationale And Objectives:
Magnetic resonance (MR) imaging has been widely used to detect bone marrow (BM) changes after radiotherapy. However, little information about the dynamic MR appearance of early radiation-induced BM injury is available. This experimental study was designed to determine the MR appearance of irradiated BM during the initial 4 weeks after irradiation.
Materials And Methods:
After focal BM irradiation (20 Gy, single dose, x-ray), 12 of 20 rabbits underwent serial MR studies weekly from days 7 to 28; eight rabbits were used for histologic investigation on days 7, 14, 21, and 28 after irradiation.
Results:
Under microscopy, early BM changes after irradiation consisted of sinusoid dilatation and congestion, followed by a progressive decrease in cellularity and later fat degeneration. All irradiated BM showed relative hyperintensity on short-inversion time inversion recovery (STIR) imaging from days 7 to 21 after irradiation and increased enhancement with gadolinium diethylenetriamine pentaacetic acid (DTPA) administration from days 7 to 28 after irradiation. However, on STIR imaging and gadolinium DTPA enhancement, the relative signal intensity of irradiated BM appeared to decline in a time-dependent way. On fast spin-echo (FSE) T1-weighted imaging, relative hyperintensity was detected in irradiated BM from day 21 after irradiation. On fat-suppressed FSE T1-weighted imaging, a slight increase in signal intensity was shown in some irradiated BM (in five of 12 rabbits) on day 7 after irradiation.
Conclusion:
STIR imaging was sensitive to early BM congestion and sinusoidal dilatation, spin-echo T1-weighted imaging was effective in detecting later fatty degeneration in irradiated BM, and gadolinium DTPA enhancement may contribute to the evaluation of BM vascular injury in response to irradiation.
Insights
Magnetic resonance (MR) imaging reveals early bone marrow (BM) changes after radiation therapy. Short-inversion time inversion recovery (STIR) and gadolinium contrast show dynamic BM injury, aiding in treatment response assessment.
Area of Science:
- Radiology
- Oncology
- Experimental Medicine
Background:
- Magnetic resonance (MR) imaging is crucial for assessing bone marrow (BM) changes post-radiotherapy.
- Limited data exists on the dynamic MR appearance of early radiation-induced BM injury.
Purpose of the Study:
- To characterize the serial MR imaging appearance of irradiated bone marrow (BM) within the first four weeks post-irradiation.
- To correlate MR findings with histological changes in radiation-induced BM injury.
Main Methods:
- Focal bone marrow (BM) irradiation (20 Gy, single dose) was administered to rabbits.
- Serial MR imaging (STIR, FSE T1-weighted, fat-suppressed FSE T1-weighted, and gadolinium DTPA enhancement) was performed weekly from day 7 to 28.
- Histological analysis of BM was conducted on days 7, 14, 21, and 28 post-irradiation.
Main Results:
- Early BM changes included sinusoid dilatation and congestion, followed by decreased cellularity and fat degeneration.
- Irradiated BM showed hyperintensity on STIR imaging (days 7-21) and increased gadolinium DTPA enhancement (days 7-28), both declining over time.
- Hyperintensity on FSE T1-weighted imaging was observed from day 21; early signal increase on fat-suppressed FSE T1-weighted imaging was noted in some cases on day 7.
Conclusions:
- STIR imaging effectively detects early BM congestion and sinusoidal dilatation post-irradiation.
- FSE T1-weighted imaging is useful for identifying later fatty degeneration in irradiated BM.
- Gadolinium DTPA enhancement aids in evaluating radiation-induced BM vascular injury.
