Why, How Often, and What Happens When We Fail: A Retrospective Analysis of Failed Fluoroscopically Guided Lumbar Punctures.

BACKGROUND AND PURPOSE: Important information regarding fluoroscopically guided lumbar puncture (FGLP) performance and referrals is lacking. The purpose of our study was to elucidate the success rate for initial FGLP attempts and re-attempts, reasons for unsuccessful FGLPs, and the relationship between clinical indications and whether patients will undergo a fluoroscopically guided re-attempt, among others. MATERIALS AND METHODS: This retrospective study analyzed failed FGLP attempts in hospitalized adult patients at an academic hospital between June 2016 and March 2022. Unsuccessful FGLPs were labeled as insufficient CSF egress. FGLP reports and patients' clinical charts were analyzed for pertinent information such as clinical indication, reason for failure, whether patients received IV fluid before fluoroscopically guided spinal puncture attempt, and which patients returned for another FGLP attempt. Patients' ages and sex were analyzed using descriptive statistics. The OR was used to investigate the relationship between the clinical indications to perform FGLP and whether patients returned for a re-attempt. RESULTS: Sixty-three of 1389 (4.5%) patients (median age, 62 years) had failed the initial FGLPs administered by 39 trainees. Twenty-eight of 63 (44.4%) patients (median age, 64 years) underwent a re-attempt within a median of 2 days after the first attempt, and 27/28 (96.4%) re-attempts were successful. A dry tap, no egress of CSF was the top reason (58.7%) for failed FGLP, and 12/13 of patients had a successful FGLP after IV hydration. Twenty-seven of 63 (43%) patients did not undergo a repeat attempt, and 100% were subsequently discharged from the hospital. There was no difference (P > .05) in the likelihood of patients returning for a repeat FGLP based on the clinical indications. CONCLUSIONS: Initial and repeat FGLPs have very high success rates. No difference exists in the likelihood of patients returning for a re-attempt based on clinical indication.

How Are We Handling Fluoroscopy-Guided Lumbar Puncture Requests? A Nationwide Survey of Practice Trends.

BACKGROUND AND PURPOSE: Referrals to perform fluoroscopy-guided lumbar punctures by neuroradiologists have increased. The purpose of our study was to determine the management of fluoroscopy-guided lumbar puncture referrals in different practice settings. MATERIALS AND METHODS: We sent an online questionnaire to neuroradiologists and radiology trainees between May and June 2020 to survey their handling of fluoroscopy-guided lumbar puncture requests, preprocedural work-up, and the use of physician extenders/trainees to perform fluoroscopy-guided lumbar punctures, among other questions. Categories were compared using ORs. RESULTS: Of the 123 US respondents, 81.3% were in combined academic and 18.7% in combined private practice groups. Regarding fluoroscopy-guided lumbar puncture referrals, 27.6% of respondents did not require a bedside lumbar puncture attempt before a fluoroscopy-guided lumbar puncture. Of private practice, 95.7%, and of academic respondents, 85.0%, were often asked to perform fluoroscopy-guided lumbar punctures by clinicians because of the clinician's lack of procedural competence. Of those, 74.8% stated that they always or sometimes agreed to the request. 41.5% of respondents stated that they would always comply with patients' requests for a fluoroscopy-guided lumbar puncture without a bedside lumbar puncture attempt, a 5.26 times higher likelihood (95% CI, 2.04-14.29) for private practice respondents. To perform fluoroscopy-guided lumbar punctures, 32.0% of academic respondents and 47.8% of private practice respondents use physician extenders. 75.0% of academic respondents reported that trainees perform >50% of their fluoroscopy-guided lumbar punctures. CONCLUSIONS: This survey demonstrates that many academic and private practice neuroradiologists engage in practices that may promote an increase in fluoroscopy-guided lumbar puncture referrals including not requiring a non-image-guided lumbar puncture attempt, complying with clinicians' requests for a fluoroscopy-guided lumbar puncture due to lack of competence in performing lumbar punctures, and fulfilling patient requests for fluoroscopy-guided lumbar punctures.

Am I Ready to Be an Independent Neuroradiologist? Objective Trends in Neuroradiology Fellows' Performance during the Fellowship Year.

BACKGROUND AND PURPOSE: Aside from basic Accreditation Council for Graduate Medical Education guidelines, few metrics are in place to monitor fellows' progress. The purpose of this study was to determine objective trends in neuroradiology fellowship training on-call performance during an academic year. MATERIALS AND METHODS: We retrospectively reviewed the number of cross-sectional neuroimaging studies dictated with complete reports by neuroradiology fellows during independent call. Monthly trends in total call cases, report turnaround times, relationships between volume and report turnaround times, and words addended to preliminary reports by attending neuroradiologists were evaluated with regression models. Monthly variation in frequencies of call-discrepancy macros were assessed via χ2 tests. Changes in frequencies of specific macro use between fellowship semesters were assessed via serial 2-sample tests of proportions. RESULTS: From 2012 to 2017, for 29 fellows, monthly median report turnaround times significantly decreased during the academic year: July (first month) = 79 minutes (95% CI, 71-86 minutes) and June (12th month) = 55 minutes (95% CI, 52-60 minutes; P value = .023). Monthly report turnaround times were inversely correlated with total volumes for CT (r = -0.70, F = 9.639, P value = .011) but not MR imaging. Words addended to preliminary reports, a surrogate measurement of report clarity, slightly improved and discrepancy rates decreased during the last 6 months of fellowship. A nadir for report turnaround times, discrepancy errors, and words addended to reports was seen in December and January. CONCLUSIONS: Progress through fellowship correlates with a decline in report turnaround times and discrepancy rates for cross-sectional neuroimaging call studies and slight improvement in indirect quantitative measurement of report clarity. These metrics can be tracked throughout the academic year, and the midyear would be a logical time point for programs to assess objective progress of fellows and address any deficiencies.

Computer-Extracted Texture Features to Distinguish Cerebral Radionecrosis from Recurrent Brain Tumors on Multiparametric MRI: A Feasibility Study.

BACKGROUND AND PURPOSE: Despite availability of advanced imaging, distinguishing radiation necrosis from recurrent brain tumors noninvasively is a big challenge in neuro-oncology. Our aim was to determine the feasibility of radiomic (computer-extracted texture) features in differentiating radiation necrosis from recurrent brain tumors on routine MR imaging (gadolinium T1WI, T2WI, FLAIR). MATERIALS AND METHODS: A retrospective study of brain tumor MR imaging performed 9 months (or later) post-radiochemotherapy was performed from 2 institutions. Fifty-eight patient studies were analyzed, consisting of a training (n = 43) cohort from one institution and an independent test (n = 15) cohort from another, with surgical histologic findings confirmed by an experienced neuropathologist at the respective institutions. Brain lesions on MR imaging were manually annotated by an expert neuroradiologist. A set of radiomic features was extracted for every lesion on each MR imaging sequence: gadolinium T1WI, T2WI, and FLAIR. Feature selection was used to identify the top 5 most discriminating features for every MR imaging sequence on the training cohort. These features were then evaluated on the test cohort by a support vector machine classifier. The classification performance was compared against diagnostic reads by 2 expert neuroradiologists who had access to the same MR imaging sequences (gadolinium T1WI, T2WI, and FLAIR) as the classifier. RESULTS: On the training cohort, the area under the receiver operating characteristic curve was highest for FLAIR with 0.79; 95% CI, 0.77-0.81 for primary (n = 22); and 0.79, 95% CI, 0.75-0.83 for metastatic subgroups (n = 21). Of the 15 studies in the holdout cohort, the support vector machine classifier identified 12 of 15 studies correctly, while neuroradiologist 1 diagnosed 7 of 15 and neuroradiologist 2 diagnosed 8 of 15 studies correctly, respectively. CONCLUSIONS: Our preliminary results suggest that radiomic features may provide complementary diagnostic information on routine MR imaging sequences that may improve the distinction of radiation necrosis from recurrence for both primary and metastatic brain tumors.

Using Body Mass Index to Predict Needle Length in Fluoroscopy-Guided Lumbar Punctures.

BACKGROUND AND PURPOSE: Predicting the appropriate needle length to use in oblique interlaminar-approach fluoroscopy-guided lumbar punctures in patients with a large body mass index is difficult. Using the wrong needle length can lead to an increased radiation dose and patient discomfort. We hypothesized that body mass index could help determine the appropriate needle length to use in patients. MATERIALS AND METHODS: We randomly selected patients who underwent oblique interlaminar-approach fluoroscopy-guided lumbar punctures and had cross-sectional imaging of the lumbar spine within 1 year of imaging (n = 50). The distance from the skin to the midlumbar spinal canal (skin-canal distance) at the level of the lumbar puncture was measured by using an oblique angle of 8.6°, which is an average of angles most often used to perform the procedure. A formula was devised using the skin-canal distance and body mass index to predict the appropriate needle length, subsequently confirmed in 45 patients. RESULTS: The body mass index and skin-canal distance were significantly higher (P < .001) in patients who underwent fluoroscopy-guided lumbar puncture with 5- or 7-inch needles (n = 22) than in patients requiring 3.5-inch needles (n = 28). Using linear regression, we determined the formula to predict the needle length as Skin-Canal Distance (inches) = 0.077 × Body Mass Index + 0.88. We found a strong correlation (P < .001) between the predicted and actual skin canal distance in 45 patients, and our formula better predicted the skin-canal distance than others. CONCLUSIONS: We designed a formula that uses body mass index to predict the appropriate needle length in oblique interlaminar-approach fluoroscopy-guided lumbar punctures and validated it by demonstrating a strong correlation between the predicted and actual skin-canal distance.

Use of Standardized Uptake Value Ratios Decreases Interreader Variability of [18F] Florbetapir PET Brain Scan Interpretation.

BACKGROUND AND PURPOSE: Fluorine-18 florbetapir is a recently developed ß-amyloid plaque positron-emission tomography imaging agent with high sensitivity, specificity, and accuracy in the detection of moderate-to-frequent cerebral cortical ß-amyloid plaque. However, the FDA has expressed concerns about the consistency of interpretation of [(18)F] florbetapir PET brain scans. We hypothesized that incorporating automated cerebral-to-whole-cerebellar standardized uptake value ratios into [(18)F] florbetapir PET brain scan interpretation would reduce this interreader variability. MATERIALS AND METHODS: This randomized, blinded-reader study used previously acquired [(18)F] florbetapir scans from 30 anonymized patients who were enrolled in the Alzheimer's Disease Neuroimaging Initiative 2. In 4 separate, blinded-reading sessions, 5 readers classified 30 cases as positive or negative for significant ß-amyloid deposition either qualitatively alone or qualitatively with additional adjunct software that determined standardized uptake value ratios. A κ coefficient was used to calculate interreader agreement with and without the use of standardized uptake value ratios. RESULTS: There was complete interreader agreement on 20/30 cases of [(18)F] florbetapir PET brain scans by using qualitative interpretation and on 27/30 scans interpreted with the adjunct use of standardized uptake value ratios. The κ coefficient for the studies read with standardized uptake value ratios (0.92) was significantly higher compared with the qualitatively read studies (0.69, P = .006). CONCLUSIONS: Use of standardized uptake value ratios improves interreader agreement in the interpretation of [(18)F] florbetapir images.

Stimulation of in vivo angiogenesis by cytokine-loaded hyaluronic acid hydrogel implants.

Crosslinked hyaluronic acid (HA) hydrogels were evaluated for their ability to elicit new microvessel growth in vivo when preloaded with one of two cytokines, vascular endothelial growth factor (VEGF) or basic fibroblast growth factor (bFGF). HA film samples were surgically implanted in the ear pinnas of mice, and the ears retrieved 7 or 14 days post implantation. Histologic analysis showed that all groups receiving an implant demonstrated significantly more microvessel density than control ears undergoing surgery but receiving no implant (p < 0.01). Moreover, aqueous administration of either growth factor produced substantially more vessel growth than an HA implant with no cytokine. However, the most striking result obtained was a dramatic synergistic interaction between HA and VEGF. Presentation of VEGF in crosslinked HA generated vessel density of NI = 6.7 at day 14, where NI is a neovascularization index defined below, more than twice the effect of the sum of HA alone (NI = 1.8) plus VEGF alone (NI=1.3). This was twice the vessel density generated by co-addition of HA and bFGF (NI=3.4, p<0.001). New therapeutic approaches for numerous pathologies could be notably enhanced by the localized, synergistic angiogenic response produced by release of VEGF from crosslinked HA films.