Defining the timing and role of acute postoperative imaging in pituitary adenoma surgery: clinical study

BACKGROUND

The ideal timing of postoperative imaging after pituitary adenoma surgery has yet to be determined. We reviewed our pituitary database to determine whether timing of routine postoperative imaging has significantly changed patients' clinical course or outcomes.

METHODS

Retrospective chart review of patients undergoing resection of pituitary adenoma at our university center between 2012 and 2017 was performed. Timing and indication for postoperative imaging, findings of immediate and delayed postoperative imaging, as well as re-operations and radiosurgery details were recorded. Visual functions such as acuity and visual fields were used as clinical outcome indicators. Statistical analysis was run using Microsoft Excel.

RESULTS

Five hundred and nineteen patients were identified; 443 had imaging data in our system and were included in the study. Early (< 90 days) MRIs were obtained in 71 patients and late (≥ 90 days) in 372 patients. We found statistical differences in our demographic groups including larger tumors in the early MRI group (early mean 12.33 cm³, late mean 4.64 cm³, p < 0.001) and higher Knosp grade (p = 0.0006). We found a significant difference in rates of return to the OR (16.9% in the early group and 4.84% in the late group; p < 0.001). There was a significant difference in the rate of residual identified on first postoperative MRI: 52.11% in the early group and 29.57% in the late group (p < 0.001). There was no difference in visual outcomes between the patient cohorts.

CONCLUSION

After surgical treatment of pituitary adenoma, MRI obtained before 3 months is associated with higher rates of return to OR but no difference in long-term clinical outcomes. Due to cost efficiency, we argue for a delayed first postoperative MRI. The timing of MRI should also be governed by other factors such as large pituitary macroadenomas or postoperative complications. We recommend a consistent institutional protocol for determining the most cost-effective follow-up of postoperative pituitary patients.

Post-operative imaging assessment of non-functioning pituitary adenomas

BACKGROUND

Non-functioning pituitary adenomas (NFAs) are the most common pituitary tumors. There is significant variability in clinical practice in terms of post-operative imaging evaluation. The objective of this manuscript is to provide an exhaustive review of published articles pertaining to the post-operative imaging evaluation of NFAs.

METHODS

The MEDLINE database was queried for studies investigating imaging for the post-operative evaluation of pituitary adenomas. From an initial search of 5589 articles, 37 articles were evaluated in detail and included in this review.

RESULTS

Magnetic resonance imaging (MRI) is the gold standard for post-operative monitoring of NFAs, although functional imaging modalities may improve identification of residual tumor in conjunction with MRI. The residual tumor can be distinguished from post-operative changes by experienced practitioners using high-resolution MRI in the immediate post-operative setting (within 1 week of surgery). However, continued imaging evolution in the appearance of residual tumor or resection cavity is expected up to 3 months post-operatively.

CONCLUSIONS

Post-operative imaging appearance of the pituitary gland, optic apparatus, and pneumocephalus patterns, correlated with the clinical outcomes. Long-term, lifetime follow-up is warranted for NFA patients who underwent surgical resection.

MR Imaging of Pituitary Region Lesions with Gadodiamide Injection

Twelve patients with known or suspected pituitary lesions underwent MR imaging with gadodiamide injection at a dose of 0.1 (n = 5) or 0.3 (n = 7) mM/kg. Six of the patients were also studied with 0.1 mM/kg gadopentetate dimeglumine. Consistent with previous reports gadodiamide injection was found to be a safe and effective contrast medium for MR imaging of the pituitary region. No additional diagnostic information was obtained using 0.3 mM/kg gadodiamide injection compared to 0.1 mM/kg gadopentetate dimeglumine in the same patients. The high dose (0.3 mM/kg) gadodiamide injection in 7 patients did not shorten the T2 value sufficiently to overwhelm the T1 shortening and leave pathologic lesions hypointense compared to precontrast studies. With the comparable relaxivities of gadodiamide injection and gadopentetate dimeglumine, similarities in results have to be expected when using these media for MR image enhancement.

Pre- and postoperative MR imaging of craniopharyngiomas

PURPOSE

To compare the pre- and postoperative MR appearance of craniopharyngiomas with respect to lesion size, tumour morphology and identification of surrounding normal structures.

MATERIAL AND METHODS

MR images obtained prior to and following craniopharyngioma resection were evaluated retrospectively in 10 patients. Tumour signal characteristics, size and extension with particular reference to the optic chiasm, the pituitary gland, the pituitary stalk and the third ventricle were evaluated.

RESULTS

Following surgery, tumour volume was reduced in all patients. In 6 patients there was further tumour volume reduction between the first and second postoperative images. Two of these patients received radiation therapy between the 2 postoperative studies, while 4 had no adjuvant treatment to the surgical intervention. There was improved visualization of the optic chiasm in 3, the pituitary stalk in one, and the third ventricle in 9 of the 10 patients. The pituitary gland was identified preoperatively only in one patient, postoperatively only in another, pre- and postoperatively in 5, and neither pre- nor postoperatively in 3 patients. In 3 patients MR imaging 0-7 days postoperatively identified tumour remnants not seen at the end of the surgical procedure. The signal intensities of solid and cystic tumour components were stable from pre- to the first postoperative MR images. Optic tract increased signal prior to surgery was gone 28 days postoperatively in one patient, but persisted on the left side for 197 days after surgery in another.

CONCLUSION

Postoperative MR imaging of craniopharyngiomas demonstrated tumour volume reduction and tumour remnants not seen at surgery. Early postoperative MR imaging of craniopharyngiomas may overestimate the size of residual tumour. Improved visualization of peritumoral structures may be achieved.