Richardson M L, Zink-Brody G C, Patten R M, Koh W J, Conrad E U
Department of Radiology SB-05, University of Washington, Seattle 98195, USA.
Skeletal Radiol. 1996 Aug;25(6):537-43. doi: 10.1007/s002560050131.
Radiation therapy is often used to treat bone und soft tissue neoplasms, and commonly results in soft tissue edema in the radiation field. However, the time course, distribution and degree of this edema have not been well characterized. Our study was carried out to better define these features of the edema seen following neutron and photon radiation therapy.
Two hundred and twenty-six patients underwent radiation therapy as part of combined modality management for musculoskeletal sarcomas between 1985 and 1993. Of these, 15 had surgical resection of their neoplasm, had no clinical evidence of recurrent disease, and had adequate MR follow-up that allowed sequential assessment of soft tissue following irradiation. Ten patients received photons with an average dose of 52.8 Gy. Five patients received neutrons with an average dose of 17.3 nGy. Sequential MR follow-up was available in these patients for an average of 22.8 months following radiation therapy. On each of the serial MR imaging studies, subcutaneous fat, muscle, and the intramuscular septa/fascial planes were graded subjectively as to size and signal intensity.
In general, soft tissue signal intensity in the radiation field initially increased over time, peaking at about 6 months for neutron-treated patients and at about 12-18 months for photon-treated patients. Signal intensity then decreased slowly over time. However, at the end of the follow-up period, signal intensity remained elevated for most patients in both groups. Signal intensity in a particular tissue was greater and tended to persist longer on STIR sequences than on T2-weighted sequences. Survival analysis of signal intensity demonstrated much longer edema survival times for neutron-treated patients than for photon-treated patients. Signal intensity increase in the intramuscular septa persisted for much longer than for fat or muscle. A mild increase in size was noted in the subcutaneous fat and intramuscular septa. Muscle, on the other hand, showed a decrease in size following treatment. This was mild for the photon-treated group and more marked for the neutron-treated group.
There is a relatively wide variation in the duration and degree of post-irradiation edema in soft tissues. This edema seems to persist longer in the intramuscular septa than in fat or muscle. Although the duration of follow-up was limited, our study suggests that this edema resolves in roughly half the photon-treated patients within 2-3 years post-treatment and in less than 20% of neutron-treated patients by 3-4 years post-treatment. Muscle atrophy was seen in both photon- and neutron-treated patients, but was more severe in the neutron-treated group.
放射治疗常用于治疗骨骼和软组织肿瘤，通常会导致放射野内的软组织水肿。然而，这种水肿的时间进程、分布和程度尚未得到很好的描述。我们开展这项研究是为了更好地明确中子和光子放射治疗后出现的水肿的这些特征。
1985年至1993年间，226例患者接受了放射治疗，作为肌肉骨骼肉瘤综合治疗模式的一部分。其中，15例患者的肿瘤接受了手术切除，没有复发性疾病的临床证据，并且有足够的磁共振成像（MR）随访资料，能够对放疗后的软组织进行连续评估。10例患者接受光子放疗，平均剂量为52.8 Gy。5例患者接受中子放疗，平均剂量为17.3 nGy。这些患者在放疗后平均22.8个月可获得连续的MR随访资料。在每一次系列MR成像研究中，对皮下脂肪、肌肉以及肌间隔/筋膜平面的大小和信号强度进行主观分级。
一般来说，放射野内的软组织信号强度最初随时间增加，中子治疗患者在约6个月时达到峰值，光子治疗患者在约12 - 18个月时达到峰值。然后信号强度随时间缓慢下降。然而，在随访期末，两组大多数患者的信号强度仍保持升高。在短TI反转恢复（STIR）序列上，特定组织的信号强度比在T2加权序列上更大，且持续时间更长。信号强度的生存分析表明，中子治疗患者的水肿存活时间比光子治疗患者长得多。肌间隔内的信号强度增加持续的时间比脂肪或肌肉长得多。皮下脂肪和肌间隔的大小有轻度增加。另一方面，肌肉在治疗后大小减小。光子治疗组这种情况较轻，中子治疗组更明显。
放疗后软组织水肿的持续时间和程度存在相对较大的差异。这种水肿在肌间隔中似乎比在脂肪或肌肉中持续时间更长。尽管随访时间有限，但我们的研究表明，在治疗后2 - 3年内，约一半接受光子治疗的患者水肿消退，而在治疗后3 - 4年，接受中子治疗的患者中不到20%的患者水肿消退。光子和中子治疗的患者均出现肌肉萎缩，但中子治疗组更严重。
