Mucosal emphysematous head and neck infections: Scoping review and a case of emphysematous tonsillitis.

Objective: This scoping review seeks to understand the existing research in otolaryngological mucosal emphysematous infections and to elucidate gaps in knowledge in the field. We also present a case of bilateral necrotizing tonsillitis in an immunocompromised patient with the first reported imaging findings of emphysematous abscess of the tonsils. Data Sources: PubMed, Embase, Web of Science. Review Methods: We conducted our review according to the Preferred Reporting Items for Systematic Reviews extension for Scoping Reviews. Patient presentation, management, and outcomes were summarized. We also describe the case of a patient with aplastic anemia found to have emphysematous tonsillitis, managed with intubation, broad spectrum intravenous antibiotics and bilateral tonsillectomy. Results: We identified seven case reports or series, involving nine total patients, who presented with emphysematous epiglottitis, supraglottitis, or tonsillitis. The hallmark imaging characteristic was submucosal "gas bubble" on computed tomography. Presenting symptoms included dysphagia, odynophagia, dysphonia, cough, and fever. Both immunocompetent and immunocompromised patients were affected. All patients were treated with broad spectrum antibiotics, and most with steroids. Patients at risk of airway compromise also underwent intubation and surgical drainage or debridement of the emphysematous infection. Conclusion: Emphysematous pharyngeal infections are rare but potentially life-threatening infections that can progress rapidly, resulting in airway compromise and sepsis in both immunocompetent and immunocompromised individuals. We highlight the importance of swift intervention, with intubation and surgical intervention often required for severe cases. More research is needed on common pathogens and patient risk factors to guide future medical and surgical management.

4D CT Parathyroid for the General Radiologist: A Pictorial Essay of Illustrative Cases.

Primary hyperparathyroidism is a morbid disease that affects multiple organ systems and causes a multitude of debilitating symptoms if not properly diagnosed and treated. Minimally invasive parathyroidectomy is now the standard of care for the treatment of primary hyperparathyroidism. In the hands of experienced high-volume surgeons, the success rate of this treatment is approximately 95%. Preoperative planning with 4-dimensional computed tomography (4DCT) is becoming increasingly common as a first line imaging modality. It is important for general radiologists to become familiar with this type of study in order to better assist their surgical colleagues. This image-rich review will discuss hyperparathyroidism, benefits, and weaknesses of different imaging modalities, 4DCT imaging protocol, relevant anatomy, expected appearance, and location of parathyroid adenomas, ectopic and atypical appearances, multigland disease and important mimics.

24/7/365 Neuroradiologist Coverage Improves Resident Perception of Educational Experience, Referring Physician Satisfaction, and Turnaround Time.

PURPOSE: To quantitatively and qualitatively assess the impact of attending neuroradiology coverage on radiology resident perceptions of the on-call experience, referring physician satisfaction, and final report turnaround times. MATERIALS AND METHODS: 24/7/365 attending neuroradiologist coverage began in October 2016 at our institution. In March 2017, an online survey of referring physicians, (emergency medicine, neurosurgery, and stroke neurology) and radiology residents was administered at a large academic medical center. Referring physicians were queried regarding their perceptions of patient care, report accuracy, timeliness, and availability of attending radiologists before and after the implementation of overnight neuroradiology coverage. Radiology residents were asked about their level of independence, workload, and education while on-call. Turnaround time (TAT) was measured over a 5-month period before and after the implementation of overnight neuroradiology coverage. RESULTS: A total of 28 of 64 referring physicians surveyed responded, for a response rate of 67%. Specifically, 19 of 23 second (junior resident on-call) and third year radiology residents (senior resident on-call) replied, 4 of 4 stroke neurology fellows replied, 8 of 21 neurosurgery residents, and 16 of 39 emergency medicine residents replied. Ninety-five percent of radiology residents stated they had adequate independence on call, 100% felt they have enough faculty support while on call, and 84% reported that overnight attending coverage has improved the educational value of their on-call experience. Residents who were present both before and after the implementation of TAT metrics thought their education, and independence had been positively affected. After overnight neuroradiology coverage, 85% of emergency physicians perceived improved accuracy of reports, 69% noted improved timeliness, and 77% found that attending radiologists were more accessible for consultation. The surveyed stroke neurology fellows and neurosurgery residents reported positive perception of the TAT, report quality, and availability of accessibility of attending radiologist. CONCLUSIONS: In concordance with prior results, overnight attending coverage significantly reduced turnaround time. As expected, referring physicians report increased satisfaction with overnight attending coverage, particularly with respect to patient care and report accuracy. In contrast to some prior studies, radiology residents reported both improved educational value of the on-call shifts and preserved independence. This may be due to the tasking the overnight neuroradiology attending with dual goals of optimized TAT, and trainee growth. Unique implementation including subspecialty trained attendings may facilitate radiology resident independence and educational experience with improved finalized report turnaround.

On the relationship of minimum detectable contrast to dose and lesion size in abdominal CT.

CT dose optimization is typically guided by pixel noise or contrast-to-noise ratio that does not delineate low contrast details adequately. We utilized the statistically defined low contrast detectability to study its relationship to dose and lesion size in abdominal CT. A realistically shaped medium sized abdomen phantom was customized to contain a cylindrical void of 4 cm diameter. The void was filled with a low contrast (1% and 2%) insert containing six groups of cylindrical targets ranging from 1.2 mm to 7 mm in size. Helical CT scans were performed using a Siemens 64-slice mCT and a GE Discovery 750 HD at various doses. After the subtractions between adjacent slices, the uniform sections of the filtered backprojection reconstructed images were partitioned to matrices of square elements matching the sizes of the targets. It was verified that the mean values from all the elements in each matrix follow a Gaussian distribution. The minimum detectable contrast (MDC), quantified by the mean signal to background difference equal to the distribution's standard deviation multiplied by 3.29, corresponding to 95% confidence level, was found to be related to the phantom specific dose and the element size by a power law (R^2 > 0.990). Independent readings on the 5 mm and 7 mm targets were compared to the measured contrast to the MDC ratios. The results showed that 93% of the cases were detectable when the measured contrast exceeds the MDC. The correlation of the MDC to the pixel noise and target size was also identified and the relationship was found to be the same for the scanners in the study. To quantify the impact of iterative reconstructions to the low contrast detectability, the noise structure was studied in a similar manner at different doses and with different ASIR blending fractions. The relationship of the dose to the blending fraction and low contrast detectability is presented.

Spontaneous retroclival hematoma in pituitary apoplexy: case series.

OBJECT: Pituitary apoplexy is a rare and potentially life-threatening disorder that is most commonly characterized by a combination of sudden headache, visual disturbance, and hypothalamic/hormonal dysfunction. In many cases, there is hemorrhagic infarction of an underlying pituitary adenoma. The resulting clinical symptoms are due to compression of the remaining pituitary, cavernous sinuses, or cranial nerves. However, there are only 2 case reports in the literature describing spontaneous retroclival expansion of hemorrhage secondary to pituitary apoplexy. Ten cases of this entity with a review of the literature are presented here. METHODS: This is a single-institution retrospective review of 2598 patients with sellar and parasellar masses during the 10-year period between 1999 and 2009. The pituitary and brain MRI and MRI studies were reviewed by 2 neuroradiologists for evidence of apoplexy, with particular attention given to retroclival extension. RESULTS: Eighteen patients (13 men and 5 women; mean age 54 years) were identified with presenting symptoms of sudden onset of headache and ophthalmoplegia, and laboratory findings consistent with pituitary apoplexy. Ten of these patients (8 men and 2 women; mean age 55 years) had imaging findings consistent with retroclival hematoma. CONCLUSIONS: Retroclival hemorrhage was seen in the majority of cases of pituitary apoplexy (56%), suggesting that it is more common than previously thought.

Differentiation of benign angiomatous and microcystic meningiomas with extensive peritumoral edema from high grade meningiomas with aid of diffusion weighted MRI.

OBJECTIVE: To determine whether angiomatous and microcystic meningiomas which mimic high grade meningiomas based on extent of peritumoral edema can be reliably differentiated as low grade tumors using normalized apparent diffusion coefficient (ADC) values. METHODS: Preoperative magnetic resonance imaging (MRI) of seventy patients with meningiomas was reviewed. Morphologically, the tumors were divided into 3 groups. Group 1 contained 12 pure microcystic, 3 pure angiomatoid and 7 mixed angiomatoid and microcystic tumors. Group 2 included World Health Organization (WHO) grade II and WHO grade III tumors, of which 28 were atypical and 9 were anaplastic meningiomas. Group 3 included WHO grade I tumors of morphology different than angiomatoid and microcystic. Peritumoral edema, normalized ADC, and cerebral blood volume (CBV) were obtained for all meningiomas. RESULTS: Edema index of tumors in group 1 and group 2 was significantly higher than in group 3. Normalized ADC value in group 1 was higher than in group 2, but not statistically significant between groups 1 and 3. CBV values showed no significant group differences. CONCLUSION: A combination of peritumoral edema index and normalized ADC value is a novel approach to preoperative differentiation between true aggressive meningiomas and mimickers such as angiomatous and microcystic meningiomas.

Anti-NMDA encephalitis: an uncommon, autoimmune mediated form of encephalitis.

We report an interesting case of a 19 year old female with findings on MRI suggestive of viral encephalitis. An extensive workup was negative for infectious causes and she was subsequently diagnosed with anti-NMDA encephalitis. Anti-NMDA encephalitis is a highly lethal but treatable form of autoimmune encephalitis that has recently been characterized. It is frequently found in young women and associated with an underlying teratoma. Although rare, this diagnosis should be considered in young females for whom a rapid onset of encephalitis cannot be explained by more common causes.

The cause of the imbalance in the neuronal network leading to seizure activity can be predicted by the electrographic pattern of the seizure onset.

This study investigates the temporal dynamics of ictal electrical activity induced by injection of the GABA(A) receptor antagonist bicuculline, and the glutamate agonist kainic acid, into the CA3 area of hippocampus. Experiments were conducted in freely moving adult Wistar rats implanted with microelectrodes in multiple brain areas. Wide-band electrical activity (0.1-3000 Hz) was recorded, and the latency of seizure onset as well as the pattern of electrical activity were investigated for each drug. The latencies between injection and the occurrence of first epileptiform events were 3.93 +/- 2.76 (+/-STD) min for bicuculline and 6.37 +/- 7.66 min for kainic acid, suggesting the existence of powerful seizure-suppressive mechanisms in the brain. Bicuculline evoked high-amplitude rhythmic epileptiform events at the site of injection which resembled interictal EEG spikes and rapidly propagated to adjacent and remote brain areas. Kainic acid evoked a completely different pattern with a gradual increase in the amplitude of 30-80 Hz activity. Whereas there was strong temporal correlation between EEG events at the site of bicuculline injection and discharges in distant areas, much less correlation was seen with kainic acid injection. Both patterns were followed by generalized ictal EEG discharges and behavioral seizures. Our results illustrate that the same area of the brain can trigger seizures with different electrographic patterns. The knowledge of the network mechanisms underlying these two distinct electrographic patterns might be helpful in designing differential strategies for preventing seizure occurrence.

Analysis of chronic seizure onsets after intrahippocampal kainic acid injection in freely moving rats.

PURPOSE: The goal of this study was to analyze the transition period between interictal and ictal activity in freely moving rats with recurrent spontaneous seizures after unilateral intrahippocampal kainic acid (KA) injection. METHODS: Pairs of tungsten electrodes (50 microm O/D) were implanted bilaterally under anesthesia at symmetrical points in the dentate gyrus (DG) and CA1 regions of anterior and posterior hippocampi and entorhinal cortex of adult Wistar rats. Stimulating electrodes were placed in the right angular bundle and KA was injected into the right posterior CA3 area of hippocampus after 1 week of baseline EEG recording. Beginning 24 h after injection, electrographic activity was recorded with video monitoring for seizures every day for 8 h/day for 60 days. RESULTS: Seventy percent of seizures started locally in the DG ipsilateral to injection, with an increase in frequency of interictal EEG spikes (hypersynchronous type, HYP), and 26% of seizures started with a decrease of EEG amplitude with parallel increase in frequency (low-voltage fast type, LVF). During HYP seizures, a significant increase was observed in amplitude of beta-gamma range frequencies, ripple frequency, and fast ripple (FR) frequency, whereas during LVF seizure, an increase was noted only in the beta-gamma range. In all cases but one, an EEG wave preceded ripple and FR oscillations. Before seizure onset, the amplitude of DG-evoked responses to single pulses decreased, whereas the amplitude of the response to the second pulse delivered at 30-ms interval increased. CONCLUSIONS: If ripple and FR oscillations indicate the seizure-generating neuronal substrate, these areas must be small and widespread, so that the probability of recording from them directly is very low. The decreased response to electrical stimulation before seizures could indicate a protective inhibitory mechanism that contains or prevents seizure occurrence. The presence of decreased paired-pulse suppression could indicate a network predisposition to follow an external input with a certain frequency.