{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,27]],"date-time":"2026-01-27T13:54:21Z","timestamp":1769522061214,"version":"3.49.0"},"reference-count":28,"publisher":"Journal of Neurosurgery Publishing Group (JNSPG)","issue":"Supplement","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JNS"],"published-print":{"date-parts":[[2006,12]]},"abstract":"<jats:sec><jats:title>Object<\/jats:title><jats:p>Gamma Knife surgery (GKS) is often the sole treatment for brain metastases. The authors hypothesized that early post-GKS measures of the relative apparent diffusion coefficient (rADC) could predict therapeutic response, recurrence, and radionecrosis prior to changes in tumor volume.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Magnetic resonance (MR) images of 25 metastatic tumors in 15 patients were reviewed. Inclusion criteria included a history of surgery or GKS, a minimum tumor diameter of 5 mm at treatment, and a minimum of two follow-up MR images. Tumor volumes were normalized to baseline, and tumor ADC values were normalized to normal-appearing white matter (rADC). A successful therapeutic response (STR) was defined by a monotonically decreasing tumor volume throughout the follow-up period. Magnetic resonance spectroscopy was used to classify non-STRs as radionecrosis or tumor recurrence.<\/jats:p><jats:p>All tumors exhibited a decreased normalized volume (mean 37%) at the first follow-up examination (range 33\u2013124 days after GKS, mean 54 days), and three distinct rADC patterns subsequently evolved: Group 1 (STR [10 cases]), monotonically decreasing volume with gradually increasing rADC; Group 2 (radionecrosis [three cases]), initial volume reduction followed by gradual increase, with initial rapidly increasing rADC followed by more gradual increase or plateau; and Group 3 (recurrent tumor [12 cases]), initial volume decrease followed by increase, with a preceding gradual decrease in the rADC.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p> The rADC patterns outperform initial post-GKS tumor volume in predicting the long-term response to treatment. Decreasing tumor volume with an increasing rADC predicts an STR. For lesions with increasing volume, antecedent rADC reduction predicts recurrence, whereas a rapidly increasing rADC predicts radionecrosis. Evaluation of the rADC at the initial post-GKS follow-up examination appears to be a useful prognostic measure of metastatic tumor response.<\/jats:p><\/jats:sec>","DOI":"10.3171\/sup.2006.105.7.175","type":"journal-article","created":{"date-parts":[[2018,11,16]],"date-time":"2018-11-16T02:24:52Z","timestamp":1542335092000},"page":"175-182","source":"Crossref","is-referenced-by-count":20,"title":["Utility of apparent diffusion coefficient in predicting the outcome of Gamma Knife\u2013treated brain metastases prior to changes in tumor volume: a preliminary study"],"prefix":"10.3171","volume":"105","author":[{"given":"Marc","family":"Goldman","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jerrold L.","family":"Boxerman","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jeffrey 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