What’s new in Neuroimaging – January 2021

1 year ago
Characteristics of Large-Vessel Occlusion Associated with COVID-19 and Ischemic Stroke.

John, P. Kesav, V.A. Mifsud, B. Piechowski-Jozwiak, J. Dibu, A. Bayrlee, H. Elkambergy, F. Roser, M.S. Elhammady, K. Zahra, and S.I. Hussain

Clinical question

To identify associations and predictors of severity, morbidity, and mortality in patients with ischemic stroke and COVID-19, especially in the large vessel obstruction (LVO) subgroup.

Methods

This was a single-center, retrospective, observational study of all consecutive patients admitted to the hospital with a diagnosis of COVID-19 and ischemic stroke with LVO from March 1 to May 25, 2020, were identified.

Baseline institutional stroke data within and outside the COVID-19 pandemic was also collected: all consecutive ischemic stroke and TIA admissions (COVID and non-COVID) seen at the hospital during a 10-week period from March 1 to May 10, 2020 and also data from the same time period in 2019. These data were used as comparison.

Data collected included demographics, stroke risk factors, clinical presentation, stroke scales, imaging results and laboratory investigations, acute treatments including intravenous thrombolysis and endovascular thrombectomy, time metrics, stroke classification and etiology, ischemic stroke subtype classification based on the Trial of Org 10172 in Acute Stroke Treatment (TOAST), clinical outcomes, and discharge disposition.

Findings and results

There were significantly more ischemic strokes in 2020 compared to the prior year (103 versus 76). LVO, including ICA, M1 and M2 segments of the MCA, and basilar artery, significantly increased in 2020 compared to the prior year (33.8% versus 18.3%).

Among the 673 patients with COVID-19 in 2020, 2.97%presented with acute ischemic stroke. Of these patients, 15 (75%) had documented LVO.

These patients were relatively young (mean age, 46.5 years), male (93%), without traditional cardiovascular risk factors, and had a severe stroke presentation. Average C-reactive protein (CRP) and D-dimer levels closest to time of stroke were in normal ranges.

LVO were observed in multiple vessels (40%), uncommonly affected vessels, and atypical locations with a large thrombus burden. Systemic thrombosis separate from large-vessel occlusion was common (26%). At short-term follow-up, stroke etiology remained undetermined in 46% of patients and functional outcome was poor.

Conclusion

These findings suggest stroke developing in the context of COVID-19 infection is more common. COVID-19 patients with stroke tend to have LVO with a more severe presentation with worse prognosis. Coagulopathy and/or endothelial dysfunction are posited as possible contributors (as reported in prior studies), although there was no specific evidence for it in this study. The authors speculate that worse outcomes may be related to systemic disease from pneumonia and acute respiratory distress syndrome compounding cerebral oxygenation and hemodynamic dysregulation.

Implications

This study raises awareness of the severe presentation and worse outcomes of LVO in COVID-19 ischemic stroke.

Senior editor comments

The presence of thrombi, especially if bulky, in multiple or atypical vessels and/or with systemic thrombotic complications appear to be hallmarks of COVID-19 related ischemic stroke to watch for.

 

Diagnostic Yield of Staging Brain MRI in Patients with Newly Diagnosed Non–Small Cell Lung Cancer

Minjae Kim, MD, Chong Hyun Suh, MD, Sang Min Lee, MD, PhD, Ho Cheol Kim, MD, Ayal A. Aizer, MD, Ted K. Yanagihara, MD, PhD, Harrison X. Bai, MD, Jeffrey P. Guenette, MD, Raymond Y. Huang, MD, PhD, Ho Sung Kim, MD, PhD

Clinical question

This study attempts to answer two questions: First, what is the diagnostic yield of staging brain MRI in patients with newly diagnosed non-small cell lung cancer (NSCLC) based on stage group? Second, does the presence of epidermal growth factor receptor (EGFR) mutation or anaplastic lymphoma kinase (ALK) rearrangement in pulmonary adenocarcinoma change the diagnostic yield of brain metastases on staging MRI?

Methods

This was a retrospective, observational, single-institution study. Patients with newly diagnosed and pathologically confirmed NSCLC were retrospectively identified from the electronic medical records of a tertiary referral hospital from November 2017 to October 2018. Inclusion criteria required enhanced staging chest CT with a formal radiology report and enhanced brain MRI performed at initial staging.

Radiology reports and clinical staging were reviewed. Diagnostic yield was defined as the proportion of patients with brain metastases among all patients. Yield was stratified into clinical stage groups per AJCC 8 guidelines, based on staging chest CT and in adenocarcinoma with epidermal growth factor receptor (EGFR) gene mutation and anaplastic lymphoma kinase (ALK) gene rearrangement.

Findings and results:

The overall diagnostic yield of staging brain MRI in newly diagnosed NSCLC was 11.9%. Broken down by lower clinical stage IA, IB, and II disease, the diagnostic yield of MRI was 0.3%, 3.8% and 4.7%, respectively.

The diagnostic yield was significantly higher in patients with adenocarcinoma (13.6%) than in patients with squamous cell carcinoma (5.9%), with an odds ratio of 1.3.

Diagnostic yield of staging brain MRI was significantly higher in patients with EGFR mutation-positive adenocarcinoma (17.5%) than EGFR mutation-negative adenocarcinoma (10.6%), (p<.001).

The overall diagnostic yield in patients with ALK-rearranged adenocarcinoma was 23.4% compared to 15.2% in patients without ALK rearrangement, but the difference was not significant.

Conclusion

The diagnostic yield of staging brain MRI in clinical stage IA NSCLC was low, but staging brain MRI had high diagnostic yield in clinical stage IB and in EGFR mutation–positive adenocarcinoma.

Implications

The particularly low diagnostic yield of staging brain MRI in clinical stage IA disease provides evidence that staging brain MRI in patients with clinical stage IA NSCLC may not be needed. Staging MRI brain appears warranted in clinical stage IB (and above) disease and in EGFR mutation-positive lung adenocarcinoma.

Senior editor comments

These findings should be useful to help guide the development of evidence-based recommendations for when to perform screening brain MRI in patients with newly diagnosed NSCLC. It may be interesting to see if larger multi-institutional studies could demonstrate a significant difference in brain metastasis detection in adenocarcinoma with ALK rearrangement.

 

Why does unilateral pulsatile tinnitus occur in patients with idiopathic intracranial hypertension?

Pengfei Zhao, Chenyu Jiang, Han Lv, Tong Zhao, Shusheng Gong, Zhenchang Wang

Clinical question

This study aims to ask the question: Is pulsatile tinnitus (PT) in patients with idiopathic intracranial hypertension (IIH) associated with identifiable vascular and osseous findings on CT scan? Specifically, are transverse sinus stenosis (TSS), venous outflow laterality (VOL), sigmoid sinus wall dehiscence (SSWD), and sigmoid sinus diverticulum (SSD) associated with PT in IIH?

Methods

This was a retrospective case control study of IIH and control subjects. Consecutive patients meeting modified Dandy criteria of IIH were screened over a 4 year period. Inclusion criteria: unilateral pulse-synchronous sound in the ear, disappearance or obvious alleviation of PT after ipsilateral neck compression, the performance of CT arteriography/venography (CTA/V) prior to therapy, and PT without arterial or neoplastic causes.

Control subjects were age and gender matched, without PT or IIH, with head and neck CTA demonstrating transverse sinus density greater than 150 HU and having no structural abnormality.

CTA characteristics reviewed included transverse sinus stenosis (TSS), venous outflow laterality (VOL), sigmoid sinus wall dehiscence (SSWD), and sigmoid sinus diverticulum (SSD). VOL was compared between the symptomatic and non-symptomatic side in IIH patients with PT and between the dominant and non-dominant side of IIH patients without PT and in controls. TSS, SSWD, and SSD were compared between the symptomatic side of IIH patients with PT, and both sides of the latter two groups.

Findings and results

The prevalence of TSS was significantly higher in IIH patients than controls (p = 0.000), but TSS had no correlation with PT within IIH patients. The prevalence of SSWD successively decreased in IIH patients with PT, IIH without PT, and controls, with significant differences between each two of three groups. The VOL and prevalence of SSD were larger in IIH patients with PT than in IIH without PT or controls. All SSDs in IIH patients with PT were accompanied with SSWD.

Conclusion

TSS prevalence in IIH patients is higher than in controls, but did not correlate with PT in IIH patients. However, the side of low VOL and the presence of ipsilateral SSWD with/without SSD correlated significantly with unilateral PT in IIH patients.

Implications

These results may facilitate better understanding of the pathophysiology and treatment of PT in IIH.

Senior editor comments

These data suggest that TSS alone is not sufficient to cause PT in IIH patients. While as radiologists we frequently look for and comment on the presence of TSS in IIH patients, we need to correlate the symptomatic side of involvement in IIH patients having unilateral PT with ipsilateral reduced VOL, SSWD and/or SSD. While the cause and effect relationship remains unknown (and difficult to establish), future studies could evaluate the effects of treatments aimed at improving venous outflow on the symptomatic side. Notably, optimal identification of SSWD and SSD requires high resolution imaging (0.6 mm axial datasets that would be obtained with temporal bone and/or CTA/CTV studies) using a bone algorithm, as done here for accurate assessment.

 

Non-EPI versus Multi-Shot EPI DWI in Cholesteatoma Detection: Correlation with Operative Findings

J.C. Benson, M.L. Carlson, and J.I. Lane

American Journal of Neuroradiology December 2020, DOI: https://doi.org/10.3174/ajnr.A6911

Clinical question:

Is readout-segmented EPI better for evaluating cholesteatoma then HASTE DWI.

What was done:

A retrospective review was completed of consecutive patients who had suspected cholesteatoma on MRI and confirmed pathology on the subsequent operation. Only included patients had MR imaging examinations that included both HASTE and readout-segmented EPI sequences.

How was it done:

A retrospective review was completed of consecutive patients who underwent high-resolution MR imaging of the temporal bone between September 20, 2011, and March 9, 2020; patients were identified using an institutional electronic medical record search engine. Inclusion criteria encompassed patients who had preoperative MR imaging, including dedicated HASTE and RESOLVE sequences for evaluating cholesteatoma. Two board-certified neuroradiologists reviewed all MR imaging examinations. All discrepancies were resolved by consensus.

Findings and results:

Every patient in the cohort had cholesteatoma confirmed at surgery. All lesions were detected on preoperative HASTE imaging. On RESOLVE sequences, 16 (69.6%) were positive, 5 (21.8%) were equivocal, and 2 (8.7%) were falsely negative. Excellent interobserver agreement was noted between reviews of both HASTE and RESOLVE sequences.

Conclusion:

The results of this study indicate that HASTE outperforms RESOLVE in the detection of primary and recidivistic cholesteatoma. HASTE imaging correctly identified lesions in all cases, while RESOLVE results were equivocal in more than one-fifth of cases and falsely negative in 2 patients.

The discrepancy between sequences may be related to the greater relative intralesional signal intensity and size on HASTE images. Because cholesteatomas appear smaller and less hyperintense on RESOLVE images, such sequences are more likely to provide equivocal and sometimes falsely negative results.

Implications:

This study’s results are in agreement with previous analyses that have found non-EPI (e.g., HASTE) sequences to be both sensitive and specific for cholesteatoma detection. HASTE is superior to RESOLVE in the detection of both primary and residual/recurrent cholesteatomas.

 

Spinal CSF-Venous Fistulas in Morbidly and Super Obese Patients with Spontaneous Intracranial Hypotension

W.I. Schievink, M. Maya, R.S. Prasad, V.S. Wadhwa, R.B. Cruz, and F.G. Moser

American Journal of Neuroradiology December 2020, DOI: https://doi.org/10.3174/ajnr.A6895

What was done:

A review was undertaken of all patients with spontaneous intracranial hypotension and a body mass index of >40 who underwent digital subtraction myelography in the lateral decubitus position to look for CSF-venous fistulas to describe the challenges in the care of patients with CSF-venous fistulas who are morbidly or super obese.

How was it done:

All patients underwent brain MR imaging and MR myelography. Also, DSM is performed with the patient under general endotracheal anesthesia with deep paralysis and suspended respiration for maximal detail and temporal resolution. A fluoroscopically guided lumbar puncture is performed at the L2–3 level with a 22-ga needle, and an opening pressure is obtained.

Findings and results:

Out of eight patients, four presented with isolated orthostatic headaches; 3, with orthostatic headaches with Valsalva-induced worsening; and 1, with isolated Valsalva induced headaches. Fundoscopic examination findings were normal in all eight patients. Brain MR imaging showed brain sagging in 7 patients and meningeal enhancement in 5 patients.

All patients had undergone spine MR imaging. Five had undergone a conventional CT myelogram, three had undergone dynamic CT myelography, and two had undergone DSMs (using general or local anesthesia). None of these investigations had shown extradural CSF collections or clear evidence of a CSF-venous fistula.

Using DSM with the patient in the lateral decubitus position, we could detect a CSF-venous fistula in 6 of the eight patients (75%). All fistulas were located in the thoracic spine, three on the right side and three on the left side.

Conclusion:

In patients with SIH due to a spinal CSF-venous fistula who are morbidly or super obese, CSF pressure often is elevated, and the risk of posttreatment rebound high-pressure headache and papilledema is increased. The yield of finding a CSF-venous fistula in this patient population using DSM is similar to that in patients who are not obese.

The detection of CSF-venous fistulas requires sophisticated imaging, and we have been using lateral decubitus DSM with the patient under general anesthesia for this purpose with excellent results.

Implications:

Although the body habitus of morbidly and super obese patients may be intimidating, it should not result in a defeatist attitude. In the present study, we detected CSF-venous fistulas in three-fourths of morbidly and super obese patients with SIH and no extradural CSF collections on spinal imaging, thus demonstrating that the yield of identifying such fistulas in this patient population can approach that of the nonobese patient population.

References
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