J Rhinol.  2020 May;27(1):28-33. 10.18787/jr.2019.00297.

Sphenoid Sinus Fat Packing in Transsphenoidal Surgery: Long-Term Fate Assessment Using Magnetic Resonance Imaging

• Hwang CS
• Whang K
• Chae HS
• Lee HS
• Lee CS
• Seo YJ
• Park DJ

• KMID: 2502791
• DOI: http://doi.org/10.18787/jr.2019.00297

Abstract

Background and Objectives
Following the transsphenoidal approach (TSA), appropriate sphenoid sinus fat packing has been preferred to prevent postoperative cerebrospinal fluid leakage; however, studies on the behavior of fat tissue transplanted in the sphenoid sinus are lacking. This study aimed to determine the long-term fate of these fat grafts using magnetic resonance imaging (MRI).
Subjects and Method
A total of 139 postoperative MRI scans of 41 patients who underwent sphenoid sinus fat packing using the standard TSA were evaluated. Additionally, MRI time series indicating the vital fat volumes were assessed postoperatively.
Results
In 82.9% of cases, the fat volumes measured in the final MRI scans declined to <20% of the initial volumes; only 4.9% of cases exhibited declines to >60% of the initial volume. The fat tissue volume decreased significantly with time, with a median half-life of 18 months. Typically, the sphenoid sinus was eventually almost filled with air rather than transplanted fat. In the subgroup analysis, the fat clearance rate was significantly lower in patients with residual tumors than in those without such remnants (p=0.013).
Conclusion
Long-term MRI surveillance of fat grafts in the sphenoid sinus revealed that the transplanted fat graft had degraded and was gradually eliminated.

Keyword

Fat grafting; Graft survival; Transsphenoidal approach; Pituitary adenomas; Magnetic resonance imaging

Figure

• 

  Fig. 1. The clearance of fat transplanted into the sphenoid sinus using postoperative magnetic resonance imaging (MRI) assessments. A: The overall tendency was for the fat tissue volume to be reduced over time, as measured by postoperative MRI. B: Comparison of the percentage of remaining fat tissue between participants with (gray) and without (black) residual tumors. Each time series was assessed by Kaplan-Meier time-to-event analysis. **: p<0.05.

• 

  Fig. 2. Representative postoperative magnetic resonance images of fat grafts in the sphenoid sinus in the presence and absence of remnant tumors. A: The immediate postoperative coronal T1-weighted magnetic resonance imaging (MRI) scan indicates surviving fat tissues as white areas in the sphenoid sinus. B: While the viable fat tissues have nearly been reabsorbed 17 months after surgery (coronal T1-weighted). C: Neither demonstrable abnormal space-occupying lesions nor signal changes in the operative field can be observed (coronal T1-gadolinium–enhanced image). For cases in which the pituitary tumor was only partially removed. D: The immediate postoperative coronal T1-weighted MRI scan reveals a hyper-intense fat signal protruding from inside the sphenoid sinus and the anterior aspect of the sella turcica. E: Fat contents are visible at 18 months postoperatively (coronal T1-weighted image). F: The postoperative 18-month coronal T1-gadolinium-enhanced MRI scan indicates a heterogeneous enhancing solid mass with extension of the left parasellar extension (asterisk) i.e., a suspected residual adenoma.

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