• Shielding Anatomy Outside of the Direct Radiation Beam: Appropriate Practice or More Harm than Good?

      Sitton, Zach; The University of Arizona College of Medicine - Phoenix; Gridley, Daniel (The University of Arizona., 2021)
      Introduction/Background: Lead shields have been used for decades to reassure patients and clinicians that radiosensitive areas (e.g., gonads, thyroid) are protected during radiography. Despite this common practice, supporting data have been limited and conflicting. Further examination of this practice is warranted to improve patient safety. The purpose of this study was to measure the effect of a pelvic lead shield on radiation dose during a chest radiograph. Methods: For 50 consecutive pediatric chest radiographs, 2 nanoDot™ dosimeters were affixed to either side of the pelvic lead shield, which was placed according to existing protocols. After the exam, dosimeters were labeled with the position (in front of or behind the shield) and a patient identifier. Radiation doses from the dosimeters were measured and recorded along with the patient’s age, gender, weight, exam type (anteroposterior or posteroanterior), and technologist identifier. For a small subset of the exams, the mA and kVp were recorded. Results: The median radiation dose measured in the front of the shield was 33.7 mrad, while the median radiation dose measured behind the shield was 33.4 mrad. The median absolute dose reduction demonstrated a statistically significant decrease of 1.01 mrad (p=0.02) behind the shield, with an interquartile range of -0.93 to 2.79 mrad. The trend did not significantly vary by technologist. There were no statistically significant trends based on patient age, weight, weight percentile for age, exam type, mA, or kVp. Discussion/Conclusion: Using a pelvic shield results in a statistically significant reduction in radiation dose behind the shield during chest radiography. However, the median dose reduction of 1.01 mrad was 3% of the total median dose and is equivalent to 1 day of natural background radiation exposure. Therefore, the difference in radiation dose in front of and behind the lead shield may be statistically but not clinically significant. Additionally, the variation between exams was large, with approximately 1/3 of the exams recording an increased dose behind the lead shield. The long-held assumption that lead shielding provides marked radiation dose reduction should be reconsidered, as the effective dose difference may be negligible and not clinically
    • Shift in electrocorticography electrode locations after surgical implantation in children

      Munter, Bryce; The University of Arizona College of Medicine - Phoenix; Foldes, Stephen (The University of Arizona., 2021)
      Interpreting electrocorticography (ECoG) in the context of neuroimaging requires that multimodal information be integrated accurately. However, the implantation of ECoG electrodes can shift the brain impacting the spatial interpretation of electrode locations in the context of pre-implant imaging. We characterized the amount of shift in ECoG electrode locations immediately after implant in a pediatric population. Electrode-shift was quantified as the difference in the electrode locations immediately after surgery (via post-operation CT) compared to the brain surface before the operation (preimplant T1 MRI). A total of 1140 ECoG contracts were assessed across 18 patients ranging from 3 to 19 (12.1 ± 4.8) years of age who underwent intracranial monitoring in preparation for epilepsy resection surgery. Patients had an average of 63 channels assessed with an average of 5.64 ± 3.27 mm shift from the pre-implant brain surface within 24 h of implant. This shift significantly increased with estimated intracranial volume, but not age. Shift also varied significantly depending of the lobe the contact was over; where contacts on the temporal and frontal lobe had less shift than the parietal. Furthermore, contacts on strips had significantly less shift than those on grids. The shift in the brain surface due to ECoG implantation could lead to a misinterpretation of contact location particularly in patients with larger intracranial volume and for grid contacts over the parietal lobes.
    • Should Gastrojejunostomy Tubes be Changed Every Three Months? A Two-Year Single Institution Retrospective Analysis of Unscheduled Gastrojejunostomy Tube Changes

      Kaur, Manroop; The University of Arizona College of Medicine - Phoenix; Wong, Kevin (The University of Arizona., 2021)
      Background: To date there is a significant lack of data on the best practices for maintaining gastrojejunostomy tubes (GJ) in pediatric medicine. Purpose: To determine the average longevity of a GJ tube, the reasons for GJ tube change, and the cumulative radiation dose associated changes. Methods: A single institution retrospective chart review of patient data over a two-year period was performed utilizing an MPower database to identify GJ exchanges/replacements. An exchange was defined as a correctly positioned GJ tube and replacement as a mispositioned GJ tube. The patients’ age, fluoroscopy time, time between change, brand of tube, and reason for replacement were recorded and statistical analysis performed. Results: 143 patients were identified, with a total of 534 GJ changes performed. There were 331 exchanges and 203 replacements. The average length between procedures was 140.6 days with an average fluoroscopy time of 1.76 minutes. Cumulative fluoroscopy time annually was significantly higher if a patient needed a replacement (11.4 minutes) versus an exchange (0.92 minutes). G-JET® brand was more likely to malfunction (8.9%) due to a valve issues compared to MIC-KEY® (3.3%), p = 0.03. MIC-KEY® was three times more likely (OR = 3.01) to be replaced for malposition or leaking, p= 0.009. Conclusion: Current guidelines set by manufacturers can be extended from 3 months to nearly 5 months. Tube replacements result in significantly higher radiation exposure compared to exchanges. Further studies are needed to ascertain whether scheduling has a lower rate of exchanges vs not scheduling.
    • Validation of PI-RADS v2 Scores at Various Non-University Radiology Practices

      Austin, Evan; The University of Arizona College of Medicine - Phoenix; Chang, John (The University of Arizona., 2021)
      Purpose: Validate the second version of the Prostate Imaging Reporting and Data System (PIRADSv2) scores in predicting positive in-bore MRI guided targeted prostate biopsy results across different non-university related institutions. Materials and Methods: This was a retrospective review of 147 patients who underwent multiparametric magnetic resonance imaging followed by in-bore MRI guided targeted prostate biopsy from 2014-2018. Lesions were rated according to PI-RADS v2 criteria. Scores were compared to MR-guided biopsy results and pre-biopsy PSA values. Results: Prostate Cancer (PCa) was detected in 54% (80/147) of patients, with more prostate cancer being detected with each increase in PI-RADS scores. Biopsy results with PI-RADS 3, 4, and 5 lesions resulted in PCa in 25.6% (10/39), 58.1% (33/55), and 86.0% (37/43) respectively. Clinically significant PCa (Gleason score ≥7) was detected in 17.9% (7/39), 52.7% (29/55), and 72% (31/43) of cases for PI-RADS 3, 4, and 5 lesions respectively. When PI-RADS scoring/biopsy results were compared across different institutions, there was no difference in the PI-RADS scoring or in positive biopsy rates.. The sensitivity, specificity, PPV, and NPV for PIRADS 3-4 were not statistically different across the institutions for detecting Gleason 7 or greater lesions. Conclusion: Our results agree with prior studies that higher PI-RADS scores are associated with clinically significant PCa and suggest lesions with PI-RADS 3-5 have sufficient evidence to warrant biopsy. Comparison of PI-RADS across different types of non-university practices revealed no difference in scoring/biopsy outcome, suggesting that PI-RADS v2 can be easily applied outside of the university medical center setting.
    • What do individuals experiencing homelessness want for their care?: A needs assessment survey

      Zeien, Justin; The University of Arizona College of Medicine - Phoenix; Hartmark-Hill, Jennifer (The University of Arizona., 2021)
      The homeless population is growing across the United States, particularly in urban areas. Homelessness has a detrimental impact on health and quality of life, especially among the unsheltered homeless population. Oftentimes, there is a disconnect between existing community services and actual needs of individuals experiencing homelessness. The purpose of this study was to identify prioritized needs in an urban unsheltered homeless population and measure associations with self-reported health. We conducted a needs assessment from April-June 2018 of 144 unsheltered homeless individuals in metro Phoenix, Arizona. The 16-question survey investigated perceptions of priority needs, sources of medical care, health literacy, and health status. Survey results were analyzed using Wilcoxon Rank Sum Test, Chi-squared analysis, and multivariable logistic regression. Most respondents (91.6%) identified food as a top need. The majority (64.1%) utilized emergency departments (EDs) as their primary source of care, and 40.1% reported suboptimal health. Suboptimal health was more likely to be reported in those who expressed transportation (OR 3.03, 95% CI: 1.30-7.07) or medical care (OR 2.47, 95% CI: 0.99-6.14) as a top priority need. Health illiteracy (OR 3.68, 95% CI: 0.76-17.9) was associated with suboptimal health, as was obtaining care at an ED (OR 2.05, 95% CI: 0.81-5.25). The data demonstrate that food security was the top priority need of this urban unsheltered population. Interventions improving accessibility to transportation, high-quality medical care, and health education should be implemented to improve the health of this population. Such interventions may also decrease care sought in ED settings. These conclusions are likely generalizable to other unsheltered homeless populations in large urban cities; however, regional and cultural differences exist. Our needs assessment may serve as a template for future needs assessments of other urban unsheltered homeless populations.