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Open Access Publications from the University of California

Scholarly Works (25 results)

  • Thesis
  • Peer Reviewed
UC San Francisco Electronic Theses and Dissertations (2018)

Objective: The primary objective of this study is to investigate the performance of augmented reality (AR) in representing and displaying 3D holographic models derived from 3D MR acquisitions. In addition, the existing picture archiving and communication system (PACS) will be examined as well.

Methods: A compatible phantom model for the 3.0T standard bore GE MRI scanner was used and fiducial markers set at various known distances were placed on the surface of the model. The distances were measured using a digital caliper, establishing the reference gold standard. Five separate configurations were created using the same phantom model by rearranging the fiducial markers. A set of six total measurements between fiducial markers were made in each configuration: two along the x-direction, two along the y-direction, and two along the z-direction. Four different 3D MR sequences were implemented to scan each configuration. The resulting 3D MR images of each sequence for every configuration were stored as digital imaging and communications in medicine (DICOM) files and sent to PACS. The corresponding six distances were then measured using the built-in PACS ruler tool. Open-source 3D rendering software programs were used to translate the DICOM files into 3D models, which were then loaded onto an AR platform. The 3D models were displayed as holograms and the overlaid distances between the fiducial markers were measured using a physical digital caliper. Since the assumptions for parametric statistical analysis were violated, the nonparametric statistical method was adopted to examine the statistical differences among the three groups (gold standard, PACS, and AR).

Results: The results showed no statistically significant difference between AR measurements and gold standard measurements (p = 0.6208). However, a statistically significant difference between PACS measurements and gold standard measurements (p = 0.0118) was present.

Conclusion: Distance measurements in AR models derived from MRI scans show no statistically significant difference compared to gold standard measurements. AR can be used to accurately measure distance for surgical planning and clinical use.

    Cover page: Evaluating the Performance of Augmented Reality in Displaying 3D Holographic Models Derived from MR Techniques
    • Article
    • Peer Reviewed
    UC San Francisco Previously Published Works (2020)
    BACKGROUND: Picture archiving and communication systems (PACS) are ubiquitously used to store, share, and view radiological information for preoperative planning across surgical specialties. Although traditional PACS software has proven reliable in terms of display accuracy and ease of use, it remains limited by its inherent representation of medical imaging in 2 dimensions. Augmented reality (AR) systems present an exciting opportunity to complement traditional PACS capabilities. OBJECTIVE: This study aims to evaluate the technical feasibility of using a novel AR platform, with holograms derived from computed tomography (CT) imaging, as a supplement to traditional PACS for presurgical planning in complex surgical procedures. METHODS: Independent readers measured objects of predetermined, anthropomorphically correlated sizes using the circumference and angle tools of standard-of-care PACS software and a newly developed augmented reality presurgical planning system (ARPPS). RESULTS: Measurements taken with the standard PACS and the ARPPS showed no statistically significant differences. Bland-Altman analysis showed a mean difference of 0.08% (95% CI -4.20% to 4.36%) for measurements taken with PACS versus ARPPS circumference tools and -1.84% (95% CI -6.17% to 2.14%) for measurements with the systems angle tools. Lins concordance correlation coefficients were 1.00 and 0.98 for the circumference and angle measurements, respectively, indicating almost perfect strength of agreement between ARPPS and PACS. Intraclass correlation showed no statistically significant difference between the readers for either measurement tool on each system. CONCLUSIONS: ARPPS can be an effective, accurate, and precise means of 3D visualization and measurement of CT-derived holograms in the presurgical care timeline.
      Cover page: Comparing Computed Tomography-Derived Augmented Reality Holograms to a Standard Picture Archiving and Communication Systems Viewer for Presurgical Planning: Feasibility Study.
      • Article
      • Peer Reviewed
      UC San Francisco Previously Published Works (2013)

      Background

      Computed-tomography-guided interventions are attractive for tissue sampling of pediatric bone lesions; however, it comes with exposure to ionizing radiation, inherent to CT and magnified by multiple passes during needle localization.

      Objective

      We evaluate a method of CT-guided bone biopsy that minimizes ionizing radiation exposure by lowering CT scanner tube current (mAs) and voltage (kVp) during each localization scan.

      Materials and methods

      We retrospectively reviewed all CT-guided bone biopsies (n = 13) over a 1-year period in 12 children. Three blinded readers identified the needle tip on the reduced-dose CT images (mAs = 50, kVp = 80) during the final localization scan at biopsy and rated the image quality as high, moderate or low.

      Results

      The image quality of the reduced-dose scans during biopsy was rated as either high or moderate, with needle tip visualized in 12 out of 13 biopsies. Twelve of 13 biopsies also returned sufficient sample for a pathological diagnosis. The average savings in exposure using the dose-reduction technique was 87%.

      Conclusion

      Our results suggest that a low mAs and kVp strategy for needle localization during CT-guided bone biopsy yields a large dose reduction and produces acceptable image quality without sacrificing yield for biopsy diagnosis.
        Cover page: Radiation dose reduction in pediatric CT-guided musculoskeletal procedures
        • Article
        • Peer Reviewed
        UC San Francisco Previously Published Works (2013)
        We report a case of a patient with anal duplication discovered incidentally at 1 year of age. Pre-operative evaluation excluded any complications or associated anomalies. She underwent surgical excision with an excellent outcome.
          Cover page: Anal duplication in a one-year-old girl
          • Article
          • Peer Reviewed
          UC San Francisco Previously Published Works (2018)
          Medical errors are a leading cause of morbidity and mortality in the medical field and are substantial contributors to medical costs. Radiologists play an integral role in the diagnosis and care of patients and, given that those in this field interpret millions of examinations annually, may therefore contribute to diagnostic errors. Errors can be categorized as a "miss" when a primary or critical finding is not observed or as a "misinterpretation" when errors in interpretation lead to an incorrect diagnosis. In this article, the authors describe the cognitive causes of such errors in diagnostic medicine, specifically in radiology. Recognizing the cognitive processes that radiologists use while interpreting images should improve one's awareness of the inherent biases that can impact decision making. The authors review the common biases that impact clinical decisions, as well as strategies to counteract or minimize the potential for misdiagnosis. System-level processes that can be implemented to minimize cognitive errors are reviewed, as well as ways to implement personal changes to minimize cognitive errors in daily practice. ©RSNA, 2017.
            Cover page: Bias in Radiology: The How and Why of Misses and Misinterpretations.
            • Article
            • Peer Reviewed
            UC San Francisco Previously Published Works (2014)
            Magnetic resonance imaging (MRI) is often used to diagnose and monitor treatment effects of juvenile spondyloarthropathy (SpA). Our objective was to describe MRI findings in juvenile SpA and determine predictors of active sacroiliitis and response to treat
              • Article
              • Peer Reviewed
              UC San Francisco Previously Published Works (2015)
              Discovery of scrotal swelling in a neonate can be a source of anxiety for parents, clinicians, and sonologists alike. This pictorial essay provides a focused review of commonly encountered scrotal masses and mimics specific to the neonatal setting. Although malignancy is a concern, it is very uncommon, as most neonatal scrotal masses are benign. Key discriminating features and management options are highlighted to improve the radiologist's ability to diagnose neonatal scrotal conditions and guide treatment decisions. Neonatal scrotal processes ranging from common to uncommon will be discussed.
                Cover page: Scrotal swelling in the neonate.
                • Article
                • Peer Reviewed
                UC San Francisco Previously Published Works (2022)

                Background

                Premature infants are at risk for multiple types of intracranial injury with potentially significant long-term neurological impact. The number of screening head ultrasounds needed to detect such injuries remains controversial.

                Objective

                To determine the rate of abnormal findings on routine follow-up head ultrasound (US) performed in infants born at ≤ 32 weeks' gestational age (GA) after initial normal screening US.

                Materials and methods

                A retrospective study was performed on infants born at ≤ 32 weeks' GA with a head US at 3-5 weeks following a normal US at 3-10 days at a tertiary care pediatric hospital from 2014 to 2020. Exclusion criteria included significant congenital anomalies, such as congenital cardiac defects necessitating surgery, congenital diaphragmatic hernia or spinal dysraphism, and clinical indications for US other than routine screening, such as sepsis, other risk factors for intracranial injury besides prematurity, or clinical neurological abnormalities. Ultrasounds were classified as normal or abnormal based on original radiology reports. Images from initial examinations with abnormal follow-up were reviewed.

                Results

                Thirty-three (14.2%) of 233 infants had 34 total abnormal findings on follow-up head US after normal initial US. Twenty-seven infants had grade 1 germinal matrix hemorrhage, and four had grade 2 intraventricular hemorrhage. Two had periventricular echogenicity and one had a focus of cerebellar echogenicity that resolved and was determined to be artifactual.

                Conclusion

                When initial screening head ultrasounds in premature infants are normal, follow-up screening ultrasounds are typically also normal. Abnormal findings are usually limited to grade 1 germinal matrix hemorrhage.
                  Cover page: Rate of head ultrasound abnormalities at one month in very premature and extremely premature infants with normal initial screening ultrasound
                  • Article
                  • Peer Reviewed
                  UC San Francisco Previously Published Works (2014)

                  Rationale and objectives

                  Modern radiology clerkships require a rigorous, in-depth curriculum usually involving a variety of educational activities. With increasingly constrained faculty time and departmental resources, finding activities that are easy to implement and of high educational value can be a challenge.

                  Materials and methods

                  We introduced a novel educational activity to our radiology clerkship in which students created independent learning modules (ILMs) that were reviewed by their classmates. Feedback surveys were used to assess the activity and guide a revision to the program. Feedback surveys after the revision were used to assess the overall perceived value of the program.

                  Results

                  Twenty-seven students in two successive sessions of our elective radiology clerkship completed the ILM activity and provided feedback. Sixty-four students in five subsequent sessions completed a modified version of the activity and provided feedback. Students in this final group rated the activity's educational value at 8.3/10, with most describing both the creation and reviewing of the ILMs as similarly or more educationally valuable than lectures (41 of 64 [64%], 48 of 64 [75%], respectively). Students indicated the target ILM length of 15 minutes was "about right" (61 of 64 [95%]), and that the overall proportion of the course dedicated to the ILM activity was appropriate (49 of 64 [77%]).

                  Conclusions

                  A novel student-created ILM activity was highly reviewed by radiology elective students, both with regard to the educational value of creating and taking the ILMs. Clerkship directors wishing to supplement their curricula with an easy-to-implement high-value activity may consider adding a student-created ILM assignment.
                    Cover page: Student-created independent learning modules: An easy high-value addition to radiology clerkships.
                    • Article
                    • Peer Reviewed
                    We reviewed the sonographic and MRI findings of tracheolaryngeal obstruction in the fetus. Conditions that can cause tracheolaryngeal obstruction include extrinsic causes such as lymphatic malformation, cervical teratoma and vascular rings and intrinsic causes such as congenital high airway obstruction syndrome (CHAOS). Accurate distinction of these conditions by sonography or MRI can help facilitate parental counseling and management, including the decision to utilize the ex utero intrapartum treatment (EXIT) procedure.
                      Cover page: Fetal tracheolaryngeal airway obstruction: prenatal evaluation by sonography and MRI
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