Segmental Imaging of the Trochlear Nerve: Anatomic and Pathologic Considerations.

BACKGROUND: The trochlear nerve (the fourth cranial nerve) is the only cranial nerve that arises from the dorsal aspect of the midbrain. The nerve has a lengthy course making it highly susceptible to injury. It is also the smallest cranial nerve and is often difficult to identify on neuroimaging. EVIDENCE ACQUISITION: High-resolution 3-dimensional skull base MRI allows for submillimeter isotropic acquisition and is optimal for cranial nerve evaluation. In this text, the detailed anatomy of the fourth cranial nerve applicable to imaging will be reviewed. RESULTS: Detailed anatomic knowledge of each segment of the trochlear nerve is necessary in patients with trochlear nerve palsy. A systematic approach to identification and assessment of each trochlear nerve segment is essential. Pathologic cases are provided for each segment. CONCLUSIONS: A segmental approach to high-resolution 3-dimensional MRI for the study of the trochlear nerve is suggested.

Differentiation of Benign and Malignant Head and Neck Lesions With Diffusion Tensor Imaging and DWI.

OBJECTIVE: The purpose of this study was to determine whether diffusion tensor imaging (DTI) can be used to differentiate between benign and malignant head and neck lesions. MATERIALS AND METHODS: This retrospective study included patients with head and neck lesions who underwent clinical MRI at 1.5 or 3 T with DWI or DTI parameters. ROI analysis was performed, with lesion-to-medulla apparent diffusion coefficient (ADC) ratios generated. RESULTS: Sixty-five patients with head and neck lesions were included (71 benign, 40 malignant). Twenty-one patients had multiple lesions. Statistically significant differences (p < 0.001) were seen in the mean ADC values ± SD of malignant and benign lesions (0.55 × 10-3 ± 0.14 × 10-3 mm2/s vs 0.89 × 10-3 ± 0.29 × 10-3 mm2/s, respectively) and in the mean ADC ratios of malignant and benign lesions (0.88 ± 0.21 vs 1.40 ± 0.44, respectively) with DTI parameters. DTI and DWI parameters produced similar mean ADC ratio values for malignant (0.88 ± 0.21 and 0.92 ± 0.54, respectively) and benign lesions (1.40 ± 0.44 and 1.79 ± 0.52, respectively). ADC ratio thresholds for predicting malignancy for DTI (ADC ratio ≤ 1) and DWI (ADC ratio ≤ 0.94) were also similar. CONCLUSION: DTI is a useful predictor of malignancy for head and neck lesions, with ADC values of malignant lesions significantly lower than those of benign lesions. DTI ADC values were lower than DWI ADC values for all head and neck lesions in our study group, often below reported malignant DWI threshold values. Normalization of ADC values to an internal control resulted in similar ADC ratios on DWI and DTI.

Do Superior or Inferior Interlaminar Approach or Bevel Orientation Predispose to Nonepidural Needle Penetration?

OBJECTIVE: There is a paucity of evidence-based literature regarding the advantages and disadvantages of the interlaminar approach and needle bevel orientation for performing a lumbar interlaminar epidural steroid injection (ESI). The purpose of this study was to determine if superior versus inferior lamina approach, needle bevel tip orientation, or both may predispose to inadvertent nonepidural penetration during lumbar interlaminar ESI. SUBJECTS AND METHODS: A prospective study was performed of patients with low back pain with or without radicular pain or neurogenic claudication referred for lumbar interlaminar ESI. Two hundred eleven patients were randomized by interlaminar approach (superior vs inferior) and bevel tip orientation (cranial vs caudal). Lumbar interlaminar ESI was performed by six interventionalists of varying levels of experience using fluoroscopic guidance with curved tip epidural needles, using loss-of-resistance technique and confirmation with contrast opacification. Exact Poisson regression was used to model the study outcome. RESULTS: Two hundred twenty-one lumbar interlaminar ESIs were performed on 211 patients, randomized to a superior (n = 121) or inferior lamina approach (n = 100) and to a cranial (n = 103) or caudal (n = 118) orientation of the bevel tip. Epidural needle placement was confirmed in 96.4% (n = 213) of cases. Nonepidural needle placement was most commonly associated with superior lamina approach and caudal bevel tip orientation, which was marginally significant (adjusted risk ratio, 6.88; 95% CI, 0.93-∞; p = 0.059). CONCLUSION: Inadvertent nonepidural needle penetration during fluoroscopically guided lumbar interlaminar ESI appears to be affected by approach, with superior lamina approach and caudal bevel tip orientation being the least favorable technique.

Acute traumatic intraosseous fluid sign predisposes to dynamic fracture mobility.

The intraosseous fluid sign (IFS) in chronic osteoporotic vertebral fractures is attributed to fluid accumulation within non-healing intervertebral clefts. IFS can also be seen in acute traumatic fractures, not previously described. We hypothesize a pathophysiological mechanism for the acute traumatic intraosseous fluid sign (ATIFS) and its predisposition to dynamic fracture mobility with axial loading on upright radiographs. Retrospective analysis was performed of 41 acute thoracic and lumbar compression or stable burst fractures with both supine CT and upright plain films completed within 1 week of each other. The presence of an intravertebral cleft with fluid attenuation and vertebral body height loss was assessed on CT scans. Changes in the fractured vertebral body height and angulation were measured on upright radiographs. The ATIFS was identified in 18 (44%) of the 41 acute fractures. Mean kyphotic angle increase was significantly greater (p = 0.000) for ATIFS fractures (8.2°, SD ±4.2) than fractures without ATIFS (1.6°, SD ±3.4). There was significantly greater mean anterior (p = 0.0009) and central (p = 0.026) height loss in ATIFS fractures (4.3 mm, SD ±3.76 and 1.89 mm, SD ±4.44, respectively) compared to fractures without ATIFS (0.59 mm, SD ±2.24 and -0.52 mm, SD ±2.01, respectively). The IFS can be seen in acute traumatic vertebral fractures and show dynamic mobility. These ATIFS fractures show statistically significant greater mean height loss ratio differences and have significantly greater changes in kyphotic angulation on upright imaging when compared to fractures without ATIFS.

Inflammatory Lesions of the Jaws.

This article defines the fascial and spatial anatomy of the suprahyoid neck region, delineates the role of CT and MR imaging, discusses the inflammatory conditions of the jaws and adjacent spaces and their clinical symptomatology, and illustrates the appearance of these conditions.

RadDiscord's Big Bang: Perspectives and Impact of Creation of a Successful Radiology Education Community.

The COVID-19 pandemic brought unprecedented challenges in radiology education. RadDiscord, a digital, open-access radiology educational platform now with over 4100 members internationally, emerged as a COVID-era innovation that has transformed radiology education, broken down institutional silos, and equalized access to high-quality education. This special report will discuss the origin of RadDiscord, overcoming early barriers, building an organization and community, innovation and impact, and the future of radiological education. This may offer helpful perspectives to trainees and educators who are interested in innovating in the realm of radiology education.

Perspectives From the RadDiscord Annual Survey: Overview of the Top Study Tools and Evaluation of Study Time and Various Resources.

RATIONALE AND OBJECTIVES: Each year, senior radiology residents take the American Board of Radiology Qualifying (Core) exam to evaluate competency. Approximately 10% of first-time examinees will fail this exam (1). Understanding factors that contribute to success will help residency program directors and trainees prepare for future exams. RadDiscord (www.raddiscord.org), an international radiology educational community, is in the unique position to evaluate different study materials and resources. The goal of this paper is to report the results from the RadDiscord survey and analyze the factors that correlate with higher exam performance and passing. MATERIALS AND METHODS: Following the February 2021, June 2021, and June 2022 exams, RadDiscord members were provided an anonymous survey, collecting information on study resources and exam scores. The collected data were analyzed using various statistical methods. Both descriptive and inferential analyses were performed. RESULTS: A total of 318 residents responded (95% passed). Significant variability in Qualifying (Core) exam performance and perceived quality of internal didactics existed between program types. Residents who did less than 2000 practice questions performed lower on the exam. The Diagnostic Radiology In-Training (DXIT) exam was the most predictive for passing and performance. Qualifying (Core) exam performance negatively correlated with study time, though certain residents did receive some benefit from study time. CONCLUSION: Many factors correlate with passing and Qualifying (Core) exam performance. Residency programs with fewer resources should consider alternative ways to support residents beyond offering study time. Residents who complete at least 2000 practice questions are more likely to pass and DXIT results can be a useful gauge to identify exam readiness.