Browsing by Author "Amrhein, Timothy J"

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    ItemOpen Access
    Cross-sectional CT Assessment of the Extent of Injectate Spread at CT Fluoroscopy-guided Cervical Epidural Interlaminar Steroid Injections.
    (Radiology, 2019-07-16) Amrhein, Timothy J; Bozdogan, Erol; Vekaria, Sunit; Patel, Prasad; Lerebours, Reginald; Luo, Sheng; Kranz, Peter G
    Background Previous studies analyzed contrast agent spread during cervical interlaminar epidural steroid injections (CILESIs) by using planar fluoroscopy and reported wide variance of the rate of spread to the ventral epidural space (VES). Cross-sectional CT allows for direct viewing of contrast agent in the VES, providing improved spread assessment and thereby informing needle placement decisions when targeting pain generators. Purpose To determine the extent of injectate spread at CT fluoroscopy-guided CILESI, with particular attention to the VES and bilateral neuroforamina, by using cross-sectional CT. Materials and Methods This study reviewed 83 consecutive CT fluoroscopy-guided CILESIs at which a postprocedural cervical spine CT was performed (June 2016 to December 2017). All procedures used the same injectate (2 mL corticosteroid, 3 mL contrast agent). Postprocedural CT scans were reviewed for the presence of contrast within the VES, dorsal epidural space, ipsilateral neuroforamen, and contralateral neuroforamen in every cervical interlaminar level. Descriptive data are presented as frequencies or means. McNemar tests or hierarchical logistic models were used to assess associations between covariates and contrast agent spread to particular locations. Results The study cohort included 73 individual patients (59% women; 43 of 73) (mean patient age, 57.6 years ± 11.5 [standard deviation]). Mean number of levels of cranial spread were 0.6 level for VES, 1.9 levels for contralateral neuroforamen, 2.1 levels for ipsilateral neuroforamen, and 3 levels for dorsal epidural space. No VES spread in any level was found with 35% (29 of 83) of injections. VES spread was more likely to occur in the level of needle placement (43%; 36 of 83) than in other interlaminar levels (19.5%; 97 of 498; P < .001). Spread was more likely to occur in the neuroforamen ipsilateral to the needle approach compared with contralateral (P < .001). Conclusion Cervical interlaminar epidural steroid injections have injectate spreads with a mean of less than one level cranially in the ventral epidural space (VES) and approximately two levels in the neuroforamen. VES spread occurs more frequently at the level of needle placement and within the ipsilateral neuroforamen. © RSNA, 2019.
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    ItemOpen Access
    Myelography Using Energy-Integrating Detector CT Versus Photon-Counting Detector CT for Detection of CSF-Venous Fistulas in Patients With Spontaneous Intracranial Hypotension.
    (AJR. American journal of roentgenology, 2024-01) Schwartz, Fides R; Kranz, Peter G; Malinzak, Michael D; Cox, David N; Ria, Francesco; McCabe, Cindy; Harrawood, Brian; Leithe, Linda G; Samei, Ehsan; Amrhein, Timothy J
    Background: CSF-venous fistulas (CVFs) are an increasingly recognized cause of spontaneous intracranial hypotension (SIH) that are often diminutive in size and exceedingly difficult to detect by conventional imaging. Objective: This study's objective was to compare EID-CT myelography and PCD-CT myelography in terms of image quality and diagnostic performance for detecting CVFs in patients with SIH. Methods: This retrospective study included 38 patients (15 men, 23 women; mean age, 55±10 years) with SIH who underwent both clinically indicated EID-CT myelography (slice thickness, 0.625 mm) and PCD-CT myelography (slice thickness, 0.2 mm; performed in ultrahigh-resolution mode) to assess for CSF leak. Three blinded radiologists reviewed examinations in random order, assessing image noise, discernibility of spinal nerve root sleeves, and overall image quality using 0-100 scales (100=highest quality), and recording locations of CVFs. Definite CVFs were defined as CVFs described in CT myelography reports using unequivocal language and showing attenuation >70 HU. Results: For all readers, PCD-CT myelography, in comparison with EID-CT myelography, showed higher image noise (reader 1: 69±19 vs 38±15; reader 2: 59±9 vs 49±13; reader 3: 57±13 vs 43±15), higher nerve root sleeve discernibility (reader 1: 84±19 vs 30±14; reader 2: 84±19 vs 70±19; reader 3: 60±13 vs 52±12), and higher overall image quality (reader 1: 84±21 vs 40±15; reader 2: 81±10 vs 72±20; reader 3: 58±11 vs 53±11) (all p<.05). Eleven patients had a definite CVF. Sensitivity and specificity for detection of definite CVF for EID-CT myelography and PCD-CT myelography for reader 1 were 45% and 96% versus 64% and 85; for reader 2 were 36% and 100% versus 55% and 96%; and for reader 3 were 45% and 100% versus 55% and 93%. For all readers, PCD-CT myelography, in comparison with EID-CT myelography, showed significantly higher sensitivity (all p<.05), without significant difference in specificity (all p>.05). Conclusion: In comparison with EID-CT myelography, PCD-CT myelography yielded significantly improved image quality with significantly higher sensitivity for CVFs without significant loss of specificity. Clinical Impact: The findings support a potential role of PCD-CT myelography in facilitating earlier diagnosis and targeted treatment of SIH, avoiding high morbidity during potentially prolonged diagnostic workups.
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    The Importance of Planning Ahead: A Three-Dimensional Analysis of the Novel Trans-Facet Corridor for Posterior Lumbar Interbody Fusion Using Segmentation Technology.
    (World neurosurgery, 2024-05) Tabarestani, Troy Q; Drossopoulos, Peter N; Huang, Chuan-Ching; Bartlett, Alyssa M; Paturu, Mounica R; Shaffrey, Christopher I; Chi, John H; Ray, Wilson Z; Goodwin, C Rory; Amrhein, Timothy J; Abd-El-Barr, Muhammad M

    Background

    The rise of minimally invasive lumbar fusions and advanced imaging technologies has facilitated the introduction of novel surgical techniques with the trans-facet approach being one of the newest additions. We aimed to quantify any pathology-driven anatomic changes to the trans-facet corridor, which could thereby alter the ideal laterality of approach to the disc space.

    Methods

    In this retrospective cohort study, we measured the areas and maximum permissible cannula diameters of the trans-facet corridor using commercially available software (BrainLab, Munich, Germany). Exiting and traversing nerve roots, thecal sacs, and lumbar vertebrae were manually segmented on T2-SPACE magnetic resonance imaging. Spondylolisthesis, disc protrusions, and disc space heights were recorded.

    Results

    A total of 118 trans-facet corridors were segmented bilaterally in 16 patients (65.6 ± 12.1 years, 43.8% female, body mass index 29.2 ± 5.1 kg/m2). The mean areas at L1-L2, L2-L3, L3-L4, and L4-L5 were 89.4 ± 24.9 mm2, 124 ± 39.4 mm2, 123 ± 26.6 mm2, and 159 ± 42.7 mm2, respectively. The mean permissible cannula diameter at the same levels were 7.85 ± 1.43 mm, 8.98 ± 1.72 mm, 8.93 ± 1.26 mm, and 10.2 ± 1.94 mm, respectively. Both parameters increased caudally. Higher degrees for spondylolisthesis were associated with larger areas and maximum cannula diameters on regression analysis (P < 0.001).

    Conclusions

    Our results illustrate that pathology, like spondylolisthesis, can increase the area of the trans-facet corridor. By understanding this effect, surgeons can better decide on the optimal approach to the disc while taking into consideration a patient's unique anatomy.