Time window for postoperative reactive enhancement after resection of brain tumors: less than 72 hours

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Early postoperative MRI within 72 hours after brain tumor surgery is commonly used to assess residual contrast-enhancing tumor. The 72-hour window is commonly accepted because previous 1.5-T MRI studies have not found confounding postoperative reactive contrast enhancement in this time frame. The sensitivity to detect contrast enhancement increases with the field strengths. Therefore, the authors aimed to assess whether the 72-hour window is also appropriate for the MRI scanner with a field strength of 3 T.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The authors retrospectively analyzed findings on early postsurgical MR images acquired in 46 patients treated for high-grade gliomas. They performed 3-T MRI within 7 days before surgery and within 72 hours thereafter. The appearance of enhancement was categorized as postoperative reactive enhancement or tumoral enhancement by comparison with the pattern and location of presurgical enhancing tumor.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Postoperative reactive enhancement was present in 15 patients (32.6%). This enhancement, not seen on presurgical MRI, had a marginal or leptomeningeal/dural pattern. In 13 patients (28.3%) postsurgical enhancement was found within the first 72 postoperative hours, with the earliest seen 22:57 hours after surgery. Subsequent MR scans in patients with postoperative reactive enhancement did not reveal tumor recurrence in these regions.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Postoperative reactive enhancement earlier than 72 hours after brain tumor surgery can be expected in about one-third of the cases in which a 3-T scanner is used. This might be due to the higher enhancement-to-brain contrast at higher field strengths. Therefore, the time window of 72 hours does not prevent reactive enhancement, which, however, can be recognized as such comparing it with presurgical enhancing tumor.</jats:p></jats:sec>

Modified Criteria for Radiographic Response Assessment in Glioblastoma Clinical Trials

“…At the time of study entry, two scans to confirm progression should be submitted consisting of at least one scan at the time of progression and one scan at Nadir or baseline. If the patient undergoes surgery (optional), then the post - surgical , pre - treatment MRI can be used as the baseline [MRI(1)], assuming it is obtained < 72 hours from surgery to reduce post-operative reactive enhancement [91, 98]. (Note: If the post-operative MRI scan is used as the baseline reference, the standardized MRI protocols must be used.)…”

Consensus recommendations on standardized magnetic resonance imaging protocols for multicenter canine brain tumor clinical trials

“…However, the MRI field strength needs to be a factor when optimizing timing of early postoperative imaging, as the degree of contrast‐enhancement of brain tumors is dependent on magnetic field strength . With the more widespread use of 3T MRI units in the clinical setting, reactive contrast‐enhancement may be detected in a significant number of patients imaged within this previously recommended 72 h early postoperative window, and may be observed as early as 24 h post‐operatively . Discrimination between the etiologies of postoperative contrast‐enhancement may also be facilitated by assessment of the location, pattern, and margination of early postoperative contrast enhancement.…”

The use of amino acid PET and conventional MRI for monitoring of brain tumor therapy

“…A recent study suggests that findings on early postoperative MRI (24–72 h) can be falsely positive (i.e., due to reactive changes, ischemia, infarctions) or even falsely-negative, particularly when a 3T MR scanner is used (Lescher et al, 2014). In line with Lescher et al, a case series with high-grade glioma patients (n = 25) compared the early postoperative MRI performed within the first 72 h after surgery with an early FET PET scan within the same time frame.…”