Utility of Early Postoperative High-Resolution Volumetric Magnetic Resonance Imaging After Transsphenoidal Pituitary Tumor Surgery

Abstract

Objective Controversy exists over the utility of early post-operative magnetic resonance imaging (MRI) after transsphenoidal pituitary surgery for macroadenomas. We investigate whether valuable information can be derived from current higher resolution scans. Methods Volumetric MRI scans were obtained in the early (<10 days) and late (>30 days) post-operative periods in a series of patients undergoing transsphenoidal pituitary surgery. The volume of the residual tumor, resection cavity, and corresponding visual field tests were recorded at each time point. Statistical analyses of changes in tumor volume and cavity size were calculated using the late MRI as the gold standard. Results 40 patients met the inclusion criteria. Pre-operative tumor volume averaged 8.8 cm3. Early postoperative assessment of average residual tumor volume (1.18 cm3) was quite accurate and did not differ statistically from late post-operative volume (1.23 cm3, p=.64), indicating the utility of early scans to measure residual tumor. Early scans were 100% sensitive and 91% specific for predicting ≥ 98% resection (p<.001, Fisher’s exact test). The average percent decrease in cavity volume from pre-operative MRI (tumor volume) to early post-operative imaging was 45% with decreases in all but 3 patients. There was no correlation between the size of the early cavity and the visual outcome. Conclusions Early high resolution volumetric MRI is valuable in determining the presence or absence of residual tumor. Cavity volume almost always decreases after surgery and a lack of decrease should alert the surgeon to possible persistent compression of the optic apparatus that may warrant re-operation.

What is the current clinical practice in pituitary adenoma surgery in Europe? European Pituitary Adenoma Surgery Survey (EU-PASS) results—technical part

“…Early postoperative MRI scans are performed routinely in 36 centres (13.4%), for selected cases in 120 centres (47.2%), while 96 centres (37.8) do not perform early MR scanning at all. The role of early imaging is often questioned, mainly because of di culty in identifying residual tumours and interpreting early postoperative changes, such as persistent cavity enlargement, accumulation of haemorrhagic material and fat packing [27]. Stofko et al showed that early postoperative MRI scan provides accurate and reliable information regarding residual tumor presence compared with reconstruction and packing materials with sensitivity 100% and speci city 97.9% [33].…”

Non-functioning pituitary adenomas: indications for pituitary surgery and post-surgical management

“…Therefore, MRI is usually performed 3–6 months after surgery, when most of the postoperative changes have disappeared [7, 52, 109, 110]. According to recent studies, early MRI has nowadays significantly higher sensitivity and specificity for detecting residual tumor than previously reported, providing valuable information to guide future care [111, 112]. The intervals for further radiological follow-up should be decided based on individual characteristics such as residual tumor size and distance from the optic chiasm.…”

Early postoperative MRI and detection of residual adenoma after transsphenoidal pituitary surgery

“…More recent studies using modern MR techniques that are now the standard of care in pituitary imaging have indicated that EPO MRI is very accurate, with efficacy similar to that of LPO MRI at 3 months. 29,34 However, these studies used LPO MRI as the gold standard by which EPO MRI was judged, and neither study addressed the consideration that EPO MRI may, in fact, be more accurate than LPO MRI. As a result, neither study used an external gold standard, such as reresection or long-term follow-up, to determine whether LPO MRI findings were accurate.…”

“…2,17,18,21,31 More recent studies have suggested that EPO MRI is as accurate as late postoperative (LPO) MRI at 3 months. 29,34 However, these studies have failed to compare both imaging tests against an independent gold standard.…”