Change in Postsurgical Cavity Size Within the First 30 Days Correlates With Extent of Surrounding Edema

Abstract

Objective Resection cavity diameter of <40 mm is required to be eligible for stereotactic radiosurgery (SRS), following gross total resection of brain metastasis at our institution. Our study evaluates the correlation between vasogenic edema and change in cavity size over 30 days. Methods Cavity size was measured on the post-operative and follow-up MRIs. Vasogenic edema was quantified as the largest axial measurement of T2 hyperintensity surrounding the resection cavity (post-operative MRI). Results Thirty-nine resection cavities (37 patients) were reviewed. There was statistically significant (Pearson coefficient=-0.35, P=0.02) negative correlation between edema and change in cavity size. An arbitrary cut-off value of 15 mm edema yielded a sensitivity of 96% and specificity of 65% (P<0.001) to predict 10% decrease in cavity size. Conclusions In patients with cavity size close to the size cutoff for SRS, rescanning closer to the date of SRS should be considered, especially if there is significant edema surrounding the cavity.

Pre-Operative Versus Post-Operative Radiosurgery of Brain Metastases—Volumetric and Dosimetric Impact of Treatment Sequence and Margin Concept

“…For the pre-operative scenario, we added only a small margin of 1 mm to the macroscopic tumor, as is standard operating procedures at our institution and many other centers similarly [24]. In the post-operative scenarios, the approach to safety margins was based on an expansion of at least 3 mm added to the visible cavity.…”

“…Consensus contouring guidelines for postoperative SRS of the resection cavity have recently been compiled [24]. A high level of overall agreement was found for the delineation of the cavity CTV.…”

“…A high level of overall agreement was found for the delineation of the cavity CTV. However, areas of relevant disagreement included the extent to which the surgical tract should be included [24]. By comparing the post-op-I (without surgical tract) and post-op-E (including surgical tract) scenarios, we aimed to evaluate the volumetric and dosimetric impact of including the complete tract, especially with regard to the dose distribution affecting the surrounding healthy brain.…”

Radionécrose cérébrale après irradiation en conditions stéréotaxiques des berges opératoires : analyse de la littérature à partir de quatre cas

“…1-4). En situation postopératoire, la forme du volume cible prévisionnel suit celle de la cavité porencé-phalique, laquelle est le plus souvent non sphérique à la différence du volume cible prévisionnel en cas de traitement de métastases en place [27]. C'était le cas du patient 3.…”

Preoperative Stereotactic Radiosurgery for Brain Metastases

“…Postoperative SRS is more complex, attributable to the need to recreate a tumor bed, correctly interpret the altered appearance of manipulated dural surfaces in superficial cases, and decisions whether or not to include portions of the surgical tract for deeper lesions (Figure 1 ). Furthermore, the tumor bed can evolve postoperatively over time, adding the challenge of delineating residual tumor from postoperative changes, and contouring an irregularly shaped target whilst ensuring coverage of all areas of prior contact for previously resected BrM ( 20 , 21 ). Retrospective analyses have found conflicting results in regards to the likelihood of surgical cavity increase vs. constriction post-operatively ( 22 , 23 ).…”