3D T2-weighted turbo spin-echo MR sequence for identifying cerebrospinal fluid leak after endoscopic endonasal pituitary surgery

Quantitative magnetic resonance imaging for evaluating of the cerebrospinal fluid kinetics with 17O-labeled water tracer: A preliminary report

The aim of this study was to evaluate the feasibility of kinetic analysis of cerebrospinal fluid (CSF) using ¹⁷O-labeled water tracer. Four subjects (two idiopathic normal pressure hydrocephalus (iNPH) and two possible AD dementia patients) were prospectively included. Injectable formulation of ¹⁷O-labeled water containing 10 mol% of H₂¹⁷O (PSO17), was intrathecally administered to the subjects with the lateral decubitus position between the 3rd and 4th lumbar vertebrae. MRI acquisitions were performed in four-time points, before PSO17 administration, 1, 8, and 24 h after PSO17 administration. The 3-dimensional fast spin echo sequence was used. After image registration for all four-time points data, polygonal regions of interest (ROIs) were set in the 14 regions to obtain the signal intensity of CSF. Each signal intensity within the ROI was converted to ¹⁷O concentration [%]. The peak concentration at one hour after administration, the slope of concentration changes after PSO17 administration [%/s], and the root mean square error (RMSE) for evaluating the performance of a fitting were calculated. There was no significant difference in peak concentration between the iNPH and AD group. The slope in the AD group (-2.25 ± 1.62 × 10^-3 [%/h]) was significantly smaller than in the iNPH group (-1.21 ± 2.31 × 10^-3 [%/h]), which suggests the speed of CSF clearance in the iNPH group was slower than AD group. The RMSE indicating the fit to the concentration change in the AD group (4.86 ± 4.74 × 10^-3) was also significantly smaller than in the iNPH group (8.64 ± 7.56 × 10^-3). The kinetic evaluation of CSF using ¹⁷O-labeled water was feasible, and this preliminary study suggests that the differentiation of iNPH and possible AD dementia can be achieved using this method.

Economic implications of localization strategies for cerebrospinal fluid rhinorrhea

BACKGROUND

The direct costs associated with different diagnostic algorithms to localize cerebrospinal fluid (CSF) rhinorrhea have not been described.

METHODS

A decision-tree analysis of imaging modalities used to localize CSF rhinorrhea was performed to compare associated direct costs. The primary outcome was cost, which was determined based on reimbursement data published by the Centers for Medicare and Medicaid Services in 2018. The model was parameterized after a literature review of published studies was performed from 1990 to 2018 to estimate the sensitivity CSF rhinorrhea localization of the following radiographic modalities: high-resolution computed tomography (HRCT), magnetic resonance cisternography (MRC), and CT cisternography (CTC). In addition to base case analysis, 1-way sensitivity analyses were also performed to evaluate the robustness of results to changes in model parameters.

RESULTS

Among patients with a high suspicion for CSF rhinorrhea, use of HRCT followed by exploration in the operating room if preliminary HRCT was negative was found to be the optimal localization modality from a cost perspective ($172.25). The next least costly algorithm was HRCT followed by MRC ($294.10). Imaging algorithms beginning with CTC were the next least costly modality ($727.37). Sensitivity analyses generally supported HRCT to be the optimal initial radiographic strategy over a wide range of parameter values.

CONCLUSION

This work advocates HRCT as first-line modality to localize CSF rhinorrhea from a cost perspective. Although algorithms beginning with MRC were on average $35 more expensive than those starting with CTC, associated risks of CTC were not modeled and may play a role in decision making.

Detection of Cerebrospinal Fluid Leaks: Is There a Radiologic Standard of Care? A Systematic Review

INTRODUCTION

Diagnosis of cerebrospinal fluid (CSF) leaks traditionally involves laboratory testing of markers and appropriate imaging. Surgical localization can be difficult, and the inability to accurately localize skull base defects leads to increased rates of repair failure and complications. Many imaging techniques localizing and identifying CSF leaks have been proposed. Comparisons of current and investigational imaging techniques used to localize CSF leaks are reviewed.

METHODS

A comprehensive and systematic search through PubMed, Scopus, and reference lists from relevant articles was completed to identify literature on sensitivities of different imaging methods for localization and detection of CSF leaks. Prospective, retrospective, and case series published since 1995 that addressed imaging techniques for CSF leaks confined to the skull base were included. Sensitivities of each major imaging technique proposed were recorded and analyzed.

RESULTS

In total, 133 studies initially were screened from 2125 studies on preliminary search. Of these, 38 studies were included based on inclusion criteria. Studies were segregated by imaging modality. A total of 1000 patients with CSF leaks subsequently were evaluated.

CONCLUSIONS

Although radionuclide cisternography has been the historical standard, recent imaging techniques have emerged considering the low sensitivity. Computed tomography cisternography with contrast also has low sensitivity, even in active leaks. Although high-resolution computed tomography is commonly the initial study of choice, magnetic resonance imaging methods, particularly 3-dimensional imaging, may prove to be a more sensitive study of choice. Computed tomography/magnetic resonance imaging combination methods may show promise in localizing CSF leaks. Stratifying by status and etiology may be an important determinant. Further studies investigating various imaging techniques for localizing CSF leaks are needed.

Anatomical Risk Factors for Intraoperative Cerebrospinal Fluid Leaks During Transsphenoidal Surgery for Pituitary Adenomas

BACKGROUND

Cerebrospinal fluid (CSF) fistulas are among the most clinically important and frequent complications of transsphenoidal surgery for pituitary adenomas. Between the adenoma and the CSF, a "barrier" exists that consists of ≤3 elements. These, from cephalad to caudad, are the arachnoid, dura mater (sellar diaphragm), and pituitary glandular tissue. The objective of the present study was to determine whether the presence or absence of any of these 3 anatomical elements would be associated with the development of an intraoperative CSF fistula.

METHODS

From November 2016 to June 2018, 40 patients with pituitary adenomas underwent surgery, by transsphenoidal endonasal access, under a microscope. All procedures were filmed in 3 dimensions. The intraoperative findings and preoperative magnetic resonance images were analyzed and compared. The patients who had developed a fistula were compared against those who had not.

RESULTS

In 20 patients, glandular tissue was identified between the tumor and subarachnoid space. In 13, dura mater was evident, and in 7, only the arachnoid was noted. An intraoperative CSF fistula occurred in 6 patients, all of whom had the arachnoid as the only barrier. The presence of a fistula was significantly more likely statistically for patients with an arachnoid-only barrier than for those with any other barrier composition (P < 0.001).

CONCLUSIONS

The anatomical architecture forming the roof of the pituitary fossa is an important determinant of intraoperative CSF fistula risk. When the barrier consists of only the arachnoid, the risk will be significantly greater than when the barrier contains additional elements. Preoperative magnetic resonance imaging would be useful to determine the type of the existing barrier.