Brain metastases are the most common malignancy of the central nervous system with poor median survival (<6 months without treatment and 11-12 months with treatment) (1-5). Radionecrosis (RN) represents tissue death caused by radiation, which can occur after high dose radiotherapy such as stereotactic radiosurgery (SRS) (6). The incidence of RN in lesions treated with SRS has been increasing. It varies from 5-25% and may occur any time after SRS, but it is more commonly observed from 7-11 months post SRS (7-9). Diagnosis of brain...

Patient's Selection 10 consecutive patients with criteria as below were enrolled to this study. a) ≥18 years of age. b) MRI-diagnosed brain metastases that had received SRS at our institution. c) Assessment by standard contrast enhanced MRI being unable to definitively differentiate between tumour recurrence and RN. Each patient went through the process as displayed on diagram 1 below. [Fig 1]

RESULTS TRAMs Analysis (Figure 1) Three regions on TRAMs were identified, based on the correlation with the initial/early contrast-enhanced T1WI (C + T1WI) as displayed on figure 1. [Fig 4] Patient Demographics (Table 1) Median age = 52 (range 41-75); Female (n=7) vs Male (n=3). Histology: Breast cancer (n=6), non-small cell lung cancer (n=3), melanoma (n=1). Tumour location: parietal lobes (n=4), cerebellum (n=3), temporal lobe, occipital lobe and caudate nucleus (n=1 each). [Fig 2] Treatment Details (Table 2) SRS dose regimens were i) 18 or...

Two previous studies (16-18) demonstrated a TRAMs pattern with contrast accumulation (red colour) more than contrast clearance (blue colour) were suggestive of non-tumour tissue and vice versa. Using the analysis method described by the studies above, 6 out of 10 cases (Fig. 3 case 2,3,8,5,9,10) were suggestive of TR, but TR was found in only 3 of these 6 samples (Fig. 3 case 3,8,9). Our findings showed that the TRAMs pattern of TR and RN overlaps (mainly the contrast clearance (blue) in the peripheral region...

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