This study demonstrates a quantitative MRI sequence able to detect signal differences in articular cartilage in asymptomatic athletes.

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Background Iatrogenic worsening of spinal injury can result in significant harm to American football players and complicate management when equipment is removed in the acute setting by inexperienced personnel. Spine imaging before removal of protective equipment mitigates this risk. There is no consensus regarding the ideal timing of equipment removal or whether current diagnostic imaging modalities are effective to detect such injuries without equipment removal. Prior data suggest that CT is a diagnostic modality for this purpose; however, radiologists’ accuracy in detecting fractures in the presence of protective equipment requires additional study. Questions/purposes (1) Does the introduction of American football equipment result in a significant reduction in sensitivity for cervical spine fracture detection? (2) Absent specific guidance as to parameters needed to establish diagnostic quality, can a radiologist determine whether such CTs are of diagnostic quality by subjectively relying on the ability to identify anatomic landmarks? Methods A pendulum device was engineered to deliver a measured axial load to the crown of cadavers to produce a variety of cervical spine fractures in 13 cadaver specimens. The cadavers were then imaged using a standardized CT protocol first without and then with protective football equipment. The images were presented to three board-certified, fellowship-trained radiologists to (1) identify all fractures from the occiput to T1 and (2) subjectively assess the diagnostic quality of the resulting CTs. A sensitivity analysis was performed against a reference standard of fractures produced by the consensus of all radiologists in this study to determine whether there was any reduction in radiologists’ ability to detect fractures once football equipment was in place. Results We found that CT scans obtained with football protective equipment in place resulted in lower sensitivity in diagnosing cervical spine injuries than CT scans obtained without pads. A total of 42 fractures were identified in the reference standard, allowing for a combined 126 possible fracture identifications between the three interpreters. Without football equipment, a combined 98 fractures were identified, whereas a combined 65 fractures were identified once the equipment was introduced. Overall, the sensitivity was reduced by 26% (52% [65 of 126] versus 78% [98 of 126] [95% CI 14.8% to 37.5%]; p < 0.001). Of the 78 total CT series imaged with football equipment, 92% (72 of 78) were considered to be of diagnostic quality. However, the study radiologists failed to identify 50% (53 of 105) of fractures present in those CT images. Conclusion The sensitivity of cervical spine fracture detection using CT is diminished in the setting of protective American football equipment. Future studies in live subjects with cervical spine fracture may be warranted to support these conclusions. Clinical Relevance These findings contradict previous studies that determined CT to be a diagnostic imaging modality to image the cervical spine through equipment. Although the interpreting radiologists consistently deemed CTs performed in the presence of helmets and shoulder pads to have subjectively diagnostic quality, numerous fractures that had been detected in the absence of equipment were missed in their presence. Furthermore, this study established that subjective approval of the appearance of an imaging study based on the ability to recognize anatomic landmarks is insufficient to reliably determine the diagnostic quality of a CT study.

Background: Fourth ventricular outlet obstruction is an infrequent but well-established cause of tetraventricular hydrocephalus characterized by marked dilatation of the ventricular system with ballooning of the foramina of Monro, Magendie, and Luschka. Multiple processes including inflammation, infection, hemorrhage, neoplasms, or congenital malformations are known to cause this pathological obstruction. However, true idiopathic fourth ventricular outlet obstruction is a rare phenomenon with only a limited number of cases reported in the literature. Case Description: A 61-year-old female presented with several months of unsteady gait, intermittent headaches, confusion, and episodes of urinary incontinence. Conventional magnetic resonance imaging demonstrated tetraventricular hydrocephalus without transependymal flow, but with ventral displacement of the brainstem and dorsal displacement of the cerebellum without an obvious obstructive lesion on pre- or post-contrast imaging prompting a diagnosis of normal pressure hydrocephalus. However, constructive interference in steady state (CISS) and half-Fourier acquisition single-shot turbo spin echo (HASTE) sequences followed by fluoroscopic dynamic cisternography suggested encystment of the fourth ventricle with thin margins of arachnoid membrane extending through the foramina of Luschka bilaterally into the pontocerebellar cistern. Operative intervention was pursued with resection of an identified arachnoid web. Postoperative imaging demonstrated marked reduction in the size of ventricular system, especially of the fourth ventricle. The patient’s symptomatology resolved a few days after the procedure. Conclusion: Here, we describe an idiopathic case initially misdiagnosed as normal pressure hydrocephalus. The present case emphasizes the necessity of CISS sequences and fluoroscopic dynamic cisternography for suspected cases of fourth ventricular outlet obstruction as these diagnostic tests may guide surgical management and lead to superior patient outcomes.