Radiation fibrosis: differentiation from recurrent tumor by MR imaging.

Abstract

Magnetic resonance (MR) images of 21 patients who had undergone radiation therapy were analyzed and compared with those of 15 patients who had untreated tumors. T2-weighted images (TR = 1,500 msec, TE = 90 msec) were most helpful in distinguishing recurrent tumor from radiation fibrosis. Radiation fibrosis, like muscle, usually remained low in signal intensity on T2-weighted images, while tumor demonstrated higher signal intensity. In no patient was the signal intensity of tumor the same or less than muscle on the T2-weighted images. However, relatively high signal intensity on T2-weighted images is not specific for tumor recurrence and may be seen in acute radiation pneumonitis, infection, hemorrhage, and even pulmonary radiation fibrosis.

Use of positron emission tomography in evaluation of brachial plexopathy in breast cancer patients

“…Indeed, in the largest published study to date on MRI imaging of brachial plexopathy in cancer patients, the overall MRI diagnosis was in disagreement with the clinicopathological diagnosis in 21% of patients (Thyagaragan et al, 1995). Regarding the distinction between radiation and neoplastic plexopathy using MRI, there are encouraging data that tumour recurrence has a higher signal intensity than radiation fibrosis on T2-weighted images (Glazer et al, 1985;Rapaport et al, 1988), although other authors have reported increased T2 signal in both metastatic and radiation plexopathy patients (Thyagaragan et al, 1995).…”

T2-Weighted MR Imaging Early after Chemoradiotherapy to Evaluate Treatment Response in Head and Neck Squamous Cell Carcinoma

“…10 On the contrary, the T2 signal is of potential value because scar tissue typically displays very low T2 signal intensity, whereas a tumor displays higher T2 signal intensity. [11][12][13][14][15][16] Although this difference in T2 signal intensity has been known for many years, there is a paucity of published data on the use of T2-weighted images in the early posttreatment period and, to our knowledge, none that combine this information with the scoring system based on the size of a residual mass.…”

Thoracic positron emission tomography using18F-fluorodeoxyglucose for the evaluation of residual mediastinal Hodgkin disease

“…MRI has been reported to provide prognostic information by discriminating between active malignant tissue and fibrosis/normal tissue in T2-weighted images. [17][18][19] However, MRI has a low sensitivity and is therefore not useful for lymphoma. 20 67 Gallium scintigraphy is a metabolic imaging technique to detect active tumor tissue, but it has disadvantages such as a low spatial resolution, lack of specificity, and difficulty in quantification of uptake.…”