Diagnostic Yield of Decubitus CT Myelography for Detection of CSF-Venous Fistulas.

BACKGROUND AND PURPOSE: Various imaging techniques have been described to detect CSF-Venous Fistulas (CVFs) in the setting of Spontaneous Intracranial Hypotension (SIH), including decubitus CT myelography (dCTM). The expected diagnostic yield of dCTM for CVF detection is not fully established. The purpose of this study was to assess the yield of dCTM among consecutive patients presenting for evaluation of possible SIH, and to examine what impact brain MRI findings of SIH had on diagnostic yield. MATERIALS AND METHODS: Single-center, retrospective cohort of consecutive patients presenting over a one-year period who underwent CTM and had no CSF identified in the epidural space. Patients with epidural CSF leaks were included in a secondary cohort. Subjects were grouped according to positioning for the myelogram, either decubitus or prone, and the presence of imaging findings of SIH on pre-procedure brain MRI. Diagnostic yields for each subgroup were calculated, and the yield of dCTM was compared to prone CTM. RESULTS: The study cohort included 302 subjects, including 247 patients with no epidural fluid. Diagnostic yield of dCTM for CVF detection among subjects with positive brain MRI and no epidural fluid was 73%. No CVFs were identified among subjects with negative brain imaging. Among subjects with epidural leak, brain MRI was negative for signs of SIH in 22%. Prone CTM identified a CVF less commonly than dCTM (43% vs. 73%, p=0.19), although the difference was not statistically significant in this small subgroup. CONCLUSIONS: We found a diagnostic yield of dCTM to be similar to the yield previously reported for digital subtraction myelography among patients with positive brain imaging. No CVFs were identified in patients with negative brain imaging; epidural CSF leaks accounted for all cases of patients who had SIH with negative brain imaging. This study provides useful data for counseling patients and helps establish a general benchmark for dCTM yield for CVF detection.ABBREVIATIONS: SIH = spontaneous intracranial hypotension; CVF = CSF-Venous Fistula; CTM = CT Myelography; dCTM = decubitus CT myelography; EBP = epidural blood patch.

Use of augmented reality for image-guided spine procedures.

PURPOSE: Because of its ability to superimpose imaging data on a patient, while anchoring the user's view to the immediate surroundings, augmented reality (AR) has the potential to dramatically improve the accuracy and reduce the time required for preoperative planning and performance of minimally invasive spine surgeries and procedures. Described and reported herein is the direct clinical application of AR navigation on a series of common percutaneous image-guided spine procedures. MATERIALS AND METHODS: AR, including a "virtual needle" (VN) asset, was used to guide and navigate a total of 18 procedures performed on 10 patients. Comparative control data were generated using a phantom model (n = 32). These data are used to determine the accuracy of AR for federal drug administration submissions. Optical codes were implemented to allow automatic and real-time registration. A manual process was used when the use of optical codes was not available. Target error, distance to the target and target size were measured for both phantom and clinical groups. Mean errors between the two groups were compared. RESULTS: Target error between the control and clinical data sets showed no significant difference. Moreover, the distance to the target site and the target size had no effect on target acquisition. CONCLUSIONS: This data set suggests that AR navigation, utilizing a VN, is an emerging, accurate, valuable additive method for surgical and procedural planning for percutaneous image-guided spinal procedures and has potential to be applied to a broad range of clinical and surgical applications.

Head-mounted display augmented reality to guide pedicle screw placement utilizing computed tomography.

PURPOSE: Augmented reality has potential to enhance surgical navigation and visualization. We determined whether head-mounted display augmented reality (HMD-AR) with superimposed computed tomography (CT) data could allow the wearer to percutaneously guide pedicle screw placement in an opaque lumbar model with no real-time fluoroscopic guidance. METHODS: CT imaging was obtained of a phantom composed of L1-L3 Sawbones vertebrae in opaque silicone. Preprocedural planning was performed by creating virtual trajectories of appropriate angle and depth for ideal approach into the pedicle, and these data were integrated into the Microsoft HoloLens using the Novarad OpenSight application allowing the user to view the virtual trajectory guides and CT images superimposed on the phantom in two and three dimensions. Spinal needles were inserted following the virtual trajectories to the point of contact with bone. Repeat CT revealed actual needle trajectory, allowing comparison with the ideal preprocedural paths. RESULTS: Registration of AR to phantom showed a roughly circular deviation with maximum average radius of 2.5 mm. Users took an average of 200 s to place a needle. Extrapolation of needle trajectory into the pedicle showed that of 36 needles placed, 35 (97%) would have remained within the pedicles. Needles placed approximated a mean distance of 4.69 mm in the mediolateral direction and 4.48 mm in the craniocaudal direction from pedicle bone edge. CONCLUSION: To our knowledge, this is the first peer-reviewed report and evaluation of HMD-AR with superimposed 3D guidance utilizing CT for spinal pedicle guide placement for the purpose of cannulation without the use of fluoroscopy.

Whole-Body Computed Tomography-Based Body Mass and Body Fat Quantification: A Comparison to Hydrostatic Weighing and Air Displacement Plethysmography.

OBJECTIVE: We correlate and evaluate the accuracy of accepted anthropometric methods of percent body fat (%BF) quantification, namely, hydrostatic weighing (HW) and air displacement plethysmography (ADP), to 2 automatic adipose tissue quantification methods using computed tomography (CT). METHODS: Twenty volunteer subjects (14 men, 6 women) received head-to-toe CT scans. Hydrostatic weighing and ADP were obtained from 17 and 12 subjects, respectively. The CT data underwent conversion using 2 separate algorithms, namely, the Schneider method and the Beam method, to convert Hounsfield units to their respective tissue densities. The overall mass and %BF of both methods were compared with HW and ADP. RESULTS: When comparing ADP to CT data using the Schneider method and Beam method, correlations were r = 0.9806 and 0.9804, respectively. Paired t tests indicated there were no statistically significant biases. Additionally, observed average differences in %BF between ADP and the Schneider method and the Beam method were 0.38% and 0.77%, respectively. The %BF measured from ADP, the Schneider method, and the Beam method all had significantly higher mean differences when compared with HW (3.05%, 2.32%, and 1.94%, respectively). CONCLUSIONS: We have shown that total body mass correlates remarkably well with both the Schneider method and Beam method of mass quantification. Furthermore, %BF calculated with the Schneider method and Beam method CT algorithms correlates remarkably well with ADP. The application of these CT algorithms have utility in further research to accurately stratify risk factors with periorgan, visceral, and subcutaneous types of adipose tissue, and has the potential for significant clinical application.

Volumetric analysis of central body fat accurately predicts incidence of diabetes and hypertension in adults.

BACKGROUND: Central adipose tissue is appreciated as a risk factor for cardiometabolic disorders. The purpose of this study was to determine the efficacy of a volumetric 3D analysis of central adipose tissue in predicting disease. Full body computerized tomography (CT) scans were obtained from 1225 female (518) and male (707) subjects, aged 18-88. Percent central body fat (%cBF) was determined by quantifying the adipose tissue volume from the dome of the liver to the pubic symphysis. Calcium score was determined from the calcium content of coronary arteries. Relationships between %cBF, BMI, and several cardiometabolic disorders were assessed controlling for age, sex, and race. RESULTS: Higher %cBF was significantly greater for those with type 2 diabetes and hypertension, but not stroke or hypercholesterolemia. Simple anthropometric determination of BMI equally correlated with diabetes and hypertension as central body fat. Calcium scoring significantly correlated with all measurements of cardiovascular health, including hypertension, hypercholesterolemia, and heart disease. CONCLUSIONS: Central body fat and BMI equally and highly predict incidence of hypertension and type 2 diabetes.