Publications by authors named "Joseph J Gemmete"

229 Publications

Skull Base Neurointerventional Techniques.

Neuroimaging Clin N Am 2021 Nov;31(4):649-664

Department of Radiology, University of Michigan, 1500 E. Medical Center Dr, B1D330A, Ann Arbor, MI 48109, USA.

Neurodiagnostic and neurointerventional radiology (NIR) play a central role in the diagnosis and treatment of skull base disorders. Noninvasive imaging modalities, including computed tomography and magnetic resonance imaging, are important in lesion localization, evaluation of lesion extent, and diagnosis, but cannot always be definitive. Image-guided skull base biopsy and percutaneous and endovascular treatment options are important tools in the diagnosis and treatment of head, neck, and skull base disorders. NIR plays an important role in the treatment of vascular disorders of the skull base. This article summarizes the imaging evaluation and interventional therapies pertinent to the skull base.
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http://dx.doi.org/10.1016/j.nic.2021.06.007DOI Listing
November 2021

Thrombus Histology as It Relates to Mechanical Thrombectomy: A Meta-Analysis and Systematic Review.

Neurosurgery 2021 Nov;89(6):1122-1131

Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.

Background: Appropriate thrombus-device interaction is critical for recanalization. Histology can serve as a proxy for mechanical properties, and thus inform technique selection.

Objective: To investigate the value of histologic characterization, we conducted a systematic review and meta-analysis on the relationship between thrombus histology and recanalization, technique, etiology, procedural efficiency, and imaging findings.

Methods: In this meta-analysis, we identified studies published between March 2010 and March 2020 reporting findings related to the histologic composition of thrombi in large vessel occlusion stroke. Studies with at least 10 patients who underwent mechanical thrombectomy using stent retriever or aspiration were considered. Only studies in which retrieved thrombi were histologically processed were included. Patient-level data were requested when data could not be directly extracted. The primary outcome assessed was the relationship between thrombus histology and angiographic outcome.

Results: A total of 22 studies encompassing 1623 patients met inclusion criteria. Clots associated with good angiographic outcome had higher red blood cell (RBC) content (mean difference [MD] 9.60%, 95% CI 3.85-15.34, P = .008). Thrombi retrieved by aspiration had less fibrin (MD -11.39, 95% CI -22.50 to -0.27, P = .046) than stent-retrieved thrombi. Fibrin/platelet-rich clots were associated with longer procedure times (MD 13.20, 95% CI 1.30-25.10, P = .037). Hyperdense artery sign was associated with higher RBC content (MD 14.17%, 95% CI 3.07-25.27, P = .027). No relationship was found between composition and etiology.

Conclusion: RBC-rich thrombi were associated with better recanalization outcomes and shorter procedure times, suggesting that preinterventional compositional characterization may yield important prognostic and therapeutic guidance.
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http://dx.doi.org/10.1093/neuros/nyab366DOI Listing
November 2021

Endoscopic and fluoroscopic-guided closure of the eustachian tube using a biliary cytology brush and liquid embolic agent for a persistent CSF leak after schwannoma resection.

BMJ Case Rep 2021 Aug 10;14(8). Epub 2021 Aug 10.

Radiology, University of Michigan Michigan Medicine, Ann Arbor, Michigan, USA.

Vestibular schwannoma is a known cause of progressive sensorineural hearing loss. Treatment options include observation, radiation therapy and surgical resection. Cerebrospinal fluid (CSF) fistula is a known postsurgical complication that can lead to CSF otorrhoea, rhinorrhoea or CSF leakage from the surgical wound. We present a case report of a patient who underwent vestibular schwannoma resection and postoperatively developed CSF rhinorrhoea, which was refractory to multiple attempts at surgical repair. This was successfully treated under endoscopic and fluoroscopic guidance using a biliary cytology brush to disrupt the surface of the eustachian tube followed by injection of n-Butyl cyanoacrylate.
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http://dx.doi.org/10.1136/bcr-2021-241861DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8356153PMC
August 2021

Survey of Interventional Radiologists Providing Endovascular Stroke Therapy in the United States.

J Vasc Interv Radiol 2021 Oct 26;32(10):1492-1494. Epub 2021 Jul 26.

Department of CardioVascular and Interventional Radiology, Inova Alexandria Hospital, Alexandria, Virginia.

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http://dx.doi.org/10.1016/j.jvir.2021.07.010DOI Listing
October 2021

Commentary: Neuroendovascular Management of Acute Ischemic Basilar Strokes: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 09;21(4):E348-E349

Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.

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http://dx.doi.org/10.1093/ons/opab251DOI Listing
September 2021

White Matter Survival within and around the Hematoma: Quantification by MRI in Patients with Intracerebral Hemorrhage.

Biomolecules 2021 06 18;11(6). Epub 2021 Jun 18.

Department of Neurosurgery, University of Michigan, Ann Arbor, MI 48109, USA.

White matter (WM) injury and survival after intracerebral hemorrhage (ICH) has received insufficient attention. WM disruption surrounding the hematoma has been documented in animal models with histology, but rarely in human ICH with noninvasive means, like magnetic resonance imaging (MRI). A few human MRI studies have investigated changes in long WM tracts after ICH remote from the hematoma, like the corticospinal tract, but have not attempted to obtain an unbiased quantification of WM changes within and around the hematoma over time. This study attempts such quantification from 3 to 30 days post ictus. Thirteen patients with mild to moderate ICH underwent diffusion tensor imaging (DTI) MRI at 3, 14, and 30 days. Fractional anisotropy (FA) maps were used to calculate the volume of tissue with FA > 0.5, both within the hematoma (lesion) and in the perilesional tissue. At day 3, the percentages of both lesional and perilesional tissue with an FA > 0.5 were significantly less than contralateral, unaffected, anatomically identical tissue. This perilesional contralateral difference persisted at day 14, but there was no significant difference at day 30. The loss of perilesional tissue with FA > 0.5 increased with increasing hematoma size at day 3 and day 14. All patients had some tissue within the lesion with FA > 0.5 at all time points. This did not decrease with duration after ictus, suggesting the persistence of white matter within the hematoma/lesion. These results outline an approach to quantify WM injury, both within and surrounding the hematoma, after mild to moderate ICH using DTI MRI. This may be important for monitoring treatment strategies, such as hematoma evacuation, and assessing efficacy noninvasively.
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http://dx.doi.org/10.3390/biom11060910DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234588PMC
June 2021

Mechanical Thrombectomy Improves Outcome for Large Vessel Occlusion Stroke after Cardiac Surgery.

J Stroke Cerebrovasc Dis 2021 Aug 19;30(8):105851. Epub 2021 May 19.

Departments of Neurosurgery, University of Michigan, Ann Arbor, Michigan. Electronic address:

Background: Stroke is a feared complication of cardiac surgery. Modern clot-retrieval techniques provide effective treatment for large vessel occlusion (LVO) strokes. The purpose of this study was to 1) report the incidence of LVO stroke after cardiac surgery at a large academic center, and 2) describe outcomes of postoperative LVO strokes.

Methods: All patients experiencing stroke within 30 days after undergoing cardiac surgery at a single center in 2014-2018 were reviewed. LVOs were identified through review of imaging and medical records, and their characteristics and clinical courses were examined.

Results: Over the study period, 7,112 cardiac surgeries, including endovascular procedures, were performed. Acute ischemic stroke within 30 days after surgery was noted in 163 patients (2.3%). Among those with a stroke, 51/163 (31.3%) had a CTA or MRA, and 15/163 (9.2%) presented with LVO stroke. For all stroke patients, the median time from surgery to stroke was 2 days (interquartile range, IQR, 0-6 days), and for patients with LVO, the median time from surgery to stroke was 4 days (IQR 0-6 days). The overall rate of postoperative LVO was 0.2% (95% CI 0.1-0.4%), though only 6/15 received thrombectomy. LVO patients receiving thrombectomy were significantly more likely to return to independent living compared to those managed medically (n = 4/6, 66.6% for mechanical thrombectomy vs. n = 0/9, 0% for medical management, P = .01). Of the 9 patients who did not get thrombectomy, 6 may currently be candidates for thrombectomy given new expanded treatment windows.

Conclusions: The rate of LVO after cardiac surgery is low, though substantially elevated above the general population, and the majority do not receive thrombectomy currently. Patients receiving thrombectomy had improved neurologic outcomes compared to patients managed medically. Optimized postoperative care may increase the rate of LVO recognition, and cardiac surgery patients and their caregivers should be aware of this effective therapy.
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http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2021.105851DOI Listing
August 2021

Intranodal lymphangiography and interstitial lymphatic embolization to treat chyluria caused by a lymphatic malformation in a pediatric patient.

Pediatr Radiol 2021 Aug 27;51(9):1762-1765. Epub 2021 Feb 27.

Department of Radiology, University of Michigan, 1500 E. Medical Center Dr., UH B1 328, Ann Arbor, MI, 48109, USA.

Chyluria is characterized by chyle in the urinary tract and often presents as milky-white urine. We present a case of chyluria from a lymphatic malformation in a 13-year-old boy diagnosed using dynamic intranodal contrast-enhanced magnetic resonance (MR) lymphangiography. This report demonstrates the utility of intranodal lymphangiography and interstitial lymphatic embolization to treat a pediatric patient presenting with persistent chyluria. Glue migration into the urinary collecting system is a potential complication of this procedure that can be mitigated by adjusting the n-butyl cyanoacrylate dilution with Lipiodol.
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http://dx.doi.org/10.1007/s00247-021-05007-wDOI Listing
August 2021

Stent-assisted coiling of cerebral aneurysms: Head to head comparison between the Neuroform Atlas and EZ stents.

Interv Neuroradiol 2021 Jun 28;27(3):353-361. Epub 2021 Jan 28.

Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.

Background: The Neuroform Atlas stent is thought to have features allowing for an improved stent delivery system. We aimed to provide a comparison of the Atlas and Neuroform EZ stents in patients treated with stent-assisted coiling.

Methods: Seventy-seven aneurysms treated with the Atlas stent and 77 aneurysms with similar characteristics treated with the EZ stent were retrospectively compared. Outcomes included angiographic occlusion per the Raymond-Roy (RR) scale, recanalization, retreatment and procedural complications.

Results: With the Atlas stent, technical success was 100% and immediate RR1 occlusion was 81.8%. Follow-up RR1 was achieved in 83.7%. The recanalization rate was 7% and the retreatment rate was 4.6%. The complication rate was 6.5% (new neurological deficit in 1.3%). With the EZ stent, technical success was 96%, immediate RR1 occlusion was 67.6% and follow-up RR1 was 67.6%. The recanalization rate was 12.7% and the retreatment rate was 14.1%. The complication rate was 10.4% (new neurological deficit in 2.6%). The rate of immediate RR1 occlusion was significantly higher with the Atlas stent ( = 0.03), and the rate of follow-up RR1 was nonsignificantly higher with the Atlas stent ( = 0.08). The retreatment rate was significantly lower with the Atlas stent ( = 0.009). There were no significant differences in the rates of recanalization ( = 0.5) and complications ( = 0.6).

Conclusions: Stent-assisted coiling with the Atlas stent is safe and effective and shows better immediate results as compared to the EZ stent, with improved overall follow-up outcomes.
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http://dx.doi.org/10.1177/1591019921989476DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8190941PMC
June 2021

Retrieval of Bard Simon Nitinol inferior vena cava filters: Approaches, technical successes, complications, and clinical outcomes.

Phlebology 2021 Aug 26;36(7):555-561. Epub 2021 Jan 26.

Department of Radiology, Division of Interventional Radiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.

Objective: The Simon Nitinol filter is a bi-level filtration device designed for permanent implantation that is no longer commercially available, but may result in similar complications to current commercially available long term indwelling temporary or permanent filters. Complications related to indwelling inferior vena cava filters include inferior vena cava thrombosis, inferior vena cava penetration, filter migration, and filter fracture. There is a paucity of reports describing the technical aspects related to retrieval of Simon Nitinol filters.

Materials And Methods: This study consisted of five patients with Simon Nitinol filters and describes the indication for retrieval, the retrieval techniques used to remove the filters, technical success, complications, and clinical course.

Results: The indications for retrieval included: abdominal pain ( = 2; 40%), iliocaval thrombosis ( = 1; 20%), identification of an intracardiac filter fragment ( = 1; 20%), and recurrent venous thromboembolic events ( = 1; 20%). Retrieval techniques included: biopsy forceps ( = 3; 60%), excimer laser extraction sheaths ( = 3; 60%), hangman modified loop snares ( = 3; 60%), rigid endobronchial forceps ( = 2; 40%), and balloon deflection ( = 2; 40%). All filters were successfully retrieved. One patient developed a post-procedural intramuscular hematoma near the site of right internal jugular sheath placement.

Conclusions: Simon Nitinol filters may be retrieved safely and effectively using advanced inferior vena cava filter retrieval techniques.
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http://dx.doi.org/10.1177/0268355520925986DOI Listing
August 2021

Society of Interventional Radiology Guidelines and Statements Division 2020 Midyear Document Review.

J Vasc Interv Radiol 2021 01;32(1):144-145

Department of Radiology, University of California, Los Angeles, Medical Center, Los Angeles, California.

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http://dx.doi.org/10.1016/j.jvir.2020.09.001DOI Listing
January 2021

Abdominal aortic aneurysm is associated with subarachnoid hemorrhage.

J Neurointerv Surg 2021 Aug 6;13(8):716-721. Epub 2020 Nov 6.

Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA

Background: Although intracranial aneurysms (IA) and abdominal aortic aneurysms (AAA) share similar risk factors, little is known about the relationship between them. Previous studies have shown an increased incidence of IA in patients with AAA, though the rate of subarachnoid hemorrhage (SAH) in patients with AAA has not been described.

Objective: To use claims data with longitudinal follow-up, to evaluate the incidence of aneurysmal SAH in patients diagnosed with AAA.

Methods: We examined longitudinally linked medical claims data from a large private insurer to determine rates of aneurysmal SAH (aSAH) and secured aSAH (saSAH) in 2004-2014 among patients with previously diagnosed AAA.

Results: We identified 62 910 patients diagnosed with AAA and compared them 5:1 with age- and sex-matched controls. Both populations were predominantly male (70.9%), with an average age of 70.8 years. Rates of hypertension (69.7% vs 50.6%) and smoking (12.8% vs 4.1%) were higher in the AAA group (p<0.0001) than in controls. Fifty admissions for aSAH were identified in patients with AAA (26/100 000 patient-years, 95% CI 19 to 44) and 115 admissions for aSAH in controls (7/100 000 years, 95% CI 6 to 9), giving an incidence rate ratio (IRR) of 3.6 (95% CI 2.6 to 5.0, p<0.0001) and a comorbidity-adjusted incidence rate ratio (IRR) of 2.8 (95% CI 1.9 to 3.9) for patients with AAA. The incidence of secured aneurysmal SAH was proportionally even higher in patients with AAA, 7 vs 2/100 000 years, IRR 4.5 (95% CI 3.2 to 6.3, p<0.0001).

Conclusion: SAH rate was elevated in patients with AAA, even after adjustment for comorbidities. Among risk factors evaluated, AAA was the strongest predictor for SAH. The relative contributions of common genetic and environmental risk factors to both diseases should be investigated.
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http://dx.doi.org/10.1136/neurintsurg-2020-016757DOI Listing
August 2021

Gianturco Z-stent placement for the treatment of chronic central venous occlusive disease: implantation of 208 stents in 137 symptomatic patients.

Diagn Interv Radiol 2021 01;27(1):72-78

Department of Radiology, Division of Vascular and Interventional Radiology, University of Washington Medical Center, Seattle, Washington, USA.

Purpose: To report the technical successes, adverse events, and long-term stent patency rates of Gianturco Z-stents for management of chronic central venous occlusive disease.

Methods: Overall, 137 patients, with mean age 48.6±16.1 years (range, 16-89 years), underwent placement of Gianturco Z-stents for chronic central venous occlusions. Presenting symptoms included lower extremity edema (n=66, 48.2%), superior vena cava syndrome (n=30, 21.9%), unilateral upper extremity swelling (n=20, 14.6%), hemodialysis fistula or catheter dysfunction (n=11, 8.0%), ascites (n=8, 5.8%), and both ascites and lower extremity edema (n=2, 1.5%). Most common etiologies of central venous occlusion were prior central venous access placement (n=58, 42.3%), extrinsic compression (n=29, 21.2%), and post-surgical anastomotic stenosis (n=27, 19.7%). Number of stents placed, stent implantation location, stent sizes, technical successes, adverse events, need for re-intervention, follow-up evaluation, stent patencies, and mortality were recorded. Technical success was defined as recanalization and stent reconstruction with restoration of in-line venous flow. Adverse events were defined by the Society of Interventional Radiology Adverse Event Classification criteria. Primary and primary-assisted stent patencies were analyzed using Kaplan-Meier analysis.

Results: In total, 208 Z-stents were placed. The three most common placement sites were the inferior vena cava (n=124, 59.6%), superior vena cava (n=44, 21.2%), and brachiocephalic veins (n=27, 13.0%). Technical success was achieved in 133 patients (97.1%). There were two (1.5%) severe adverse events (two cases of stent migration to the right atrium), one (0.7%) moderate adverse event, and one (0.7%) mild adverse event. Mean follow-up was 43.6±52.7 months. Estimated 1-, 3-, and 5-year primary stent patency was 84.2%, 84.2%, and 82.1%, respectively. Estimated 1-, 3-, and 5-year primary-assisted patency was 92.3%, 89.6%, and 89.6%, respectively. The 30- and 60- day mortality rates were 2.9% (n=4) and 5.1% (n=7), none of which were directly attributable to Z-stent placement.

Conclusion: Gianturco Z-stent placement is safe and effective for the treatment for chronic central venous occlusive disease with durable short- and long-term patencies.
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http://dx.doi.org/10.5152/dir.2020.19282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7837711PMC
January 2021

Endovascular Treatment of Arteriovenous Malformations of the Head and Neck: Focus on the Yakes Classification and Outcomes.

J Vasc Interv Radiol 2020 Nov 18;31(11):1810-1816. Epub 2020 Sep 18.

Department of Radiology, University of Michigan, Ann Arbor, Michigan; Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan. Electronic address:

Purpose: To evaluate endovascular treatment of head and neck arteriovenous malformations (AVMs) based on the Yakes AVM classification and correlate treatment approach with clinical and angiographic outcomes.

Materials And Methods: A retrospective single-center study was performed in patients who underwent endovascular treatment of head and neck AVMs between January 2005 and December 2017. Clinical and operative records, imaging, and postoperative courses of patients were reviewed. Clinical stage was determined according to the Schobinger classification. AVM architecture and treatment approaches were determined according to the Yakes classification. Primary outcomes were clinical and angiographic treatment success rates and complication rates, with analysis according to the Yakes classification.

Results: A total of 29 patients (15 females) were identified, with a mean age of 30.6 years. Downgrading of the Schobinger clinical classification was achieved in all patients. Lesions included 8 Yakes type IIa, 5 type IIb, 1 type IIIa and IIIb, and 14 type IV. Lesions were treated using an intra-arterial, nidal, or transvenous approach, using ethanol and liquid embolic agents. Arteriovenous shunt eradication of >90% was achieved in 22 of 28 patients (79%), including 9 of 13 (69%) of Yakes type IV lesions and 13 of 15 (87%) of the other types. There were 5 significant complications in 79 procedures (6%), including 4 of 50 (8%) in Yakes type IV lesions.

Conclusions: Schobinger stage was downgraded in all patients. Arteriovenous shunt eradication of >90% was achieved in most patients. Yakes type IV lesions required more sessions, and shunt eradication was higher in the Yakes II and III groups.
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http://dx.doi.org/10.1016/j.jvir.2020.01.036DOI Listing
November 2020

Drivers of variation in 90-day episode payments after mechanical thrombectomy for acute ischemic stroke.

J Neurointerv Surg 2021 Jun 31;13(6):519-523. Epub 2020 Jul 31.

Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA

Background: Although mechanical thrombectomy for acute ischemic stroke from a large vessel occlusion is now the standard of care, little is known about cost variations in stroke patients following thrombectomy and factors that influence these variations.

Methods: We evaluated claims data for 2016 to 2018 for thrombectomy-performing hospitals within Michigan through a registry that includes detailed episode payment information for both Medicare and privately insured patients. We aimed to analyze price-standardized and risk-adjusted 90-day episode payments in patients who underwent thrombectomy. Hospitals were grouped into three payment terciles for comparison. Statistical analysis was carried out using unpaired -test, Chi-square, and ANOVA tests.

Results: 1076 thrombectomy cases treated at 16 centers were analyzed. The average 90-day episode payment by hospital ranged from $53 046 to $81,767, with a mean of $65 357. A $20 467 difference (35.1%) existed between the high and low payment hospital terciles (P<0.0001), highlighting a significant payment variation across hospital terciles. The primary drivers of payment variation were related to post-discharge care which accounted for 38% of the payment variation (P=0.0058, inter-tercile range $11,977-$19,703) and readmissions accounting for 26% (P=0.016, inter-tercile range $3,315-$7,992). This was followed by professional payments representing 20% of the variation (P<0.0001, inter-tercile range $7525-$9,922), while index hospitalization payment was responsible for only 16% of the 90-day episode payment variation (P=0.10, inter-tercile range $35,432-$41,099).

Conclusions: There is a wide variation in 90-day episode payments for patients undergoing mechanical thrombectomy across centers. The main drivers of payment variation are related to differences in post-discharge care and readmissions.
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http://dx.doi.org/10.1136/neurintsurg-2020-016389DOI Listing
June 2021

Treatment Strategies for Tandem Occlusions in Acute Ischemic Stroke.

Semin Intervent Radiol 2020 Jun 14;37(2):207-213. Epub 2020 May 14.

Department of Radiology, Michigan Medicine, Ann Arbor, Michigan.

There is no consensus for the treatment of a tandem occlusion (TO) in a patient presenting with an acute ischemic stroke. In this review article, we will focus on the controversial treatment strategies for TOs. First, we will discuss treatment options including retrograde, antegrade, and delayed approaches. Second, the role of carotid stent placement versus balloon angioplasty for the extracranial occlusion will be presented. Third, anticoagulation and antiplatelet regimens for the treatment TOs published in the literature will be reviewed. Finally, we will discuss whether there is a role for coil occlusion of the cervical carotid artery or whether staged carotid revascularization days after mechanical thrombectomy of the intracranial occlusion maybe appropriate. The optimal treatment strategy of TO has not been established and further larger trials need to be performed to answer the question.
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http://dx.doi.org/10.1055/s-0040-1709207DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224971PMC
June 2020

Analysis of human emboli and thrombectomy forces in large-vessel occlusion stroke.

J Neurosurg 2020 Feb 28;134(3):893-901. Epub 2020 Feb 28.

Departments of3Neurosurgery and.

Objective: This study's purpose was to improve understanding of the forces driving the complex mechanical interaction between embolic material and current stroke thrombectomy devices by analyzing the histological composition and strength of emboli retrieved from patients and by evaluating the mechanical forces necessary for retrieval of such emboli in a middle cerebral artery (MCA) bifurcation model.

Methods: Embolus analogs (EAs) were generated and embolized under physiological pressure and flow conditions in a glass tube model of the MCA. The forces involved in EA removal using conventional endovascular techniques were described, analyzed, and categorized. Then, 16 embolic specimens were retrieved from 11 stroke patients with large-vessel occlusions, and the tensile strength and response to stress were measured with a quasi-static uniaxial tensile test using a custom-made platform. Embolus compositions were analyzed and quantified by histology.

Results: Uniaxial tension on the EAs led to deformation, elongation, thinning, fracture, and embolization. Uniaxial tensile testing of patients' emboli revealed similar soft-material behavior, including elongation under tension and differential fracture patterns. At the final fracture of the embolus (or dissociation), the amount of elongation, quantified as strain, ranged from 1.05 to 4.89 (2.41 ± 1.04 [mean ± SD]) and the embolus-generated force, quantified as stress, ranged from 63 to 2396 kPa (569 ± 695 kPa). The ultimate tensile strain of the emboli increased with a higher platelet percentage, and the ultimate tensile stress increased with a higher fibrin percentage and decreased with a higher red blood cell percentage.

Conclusions: Current thrombectomy devices remove emboli mostly by applying linear tensile forces, under which emboli elongate until dissociation. Embolus resistance to dissociation is determined by embolus strength, which significantly correlates with composition and varies within and among patients and within the same thrombus. The dynamic intravascular weakening of emboli during removal may lead to iatrogenic embolization.
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http://dx.doi.org/10.3171/2019.12.JNS192187DOI Listing
February 2020

The Predictive Value of the HOSPITAL Score and LACE Index for an Adult Neurosurgical Population: A Prospective Analysis.

World Neurosurg 2020 05 27;137:e166-e175. Epub 2020 Jan 27.

Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA. Electronic address:

Objective: The HOSPITAL score (HS) and LACE index (LI) are 2 validated methods for quantifying the risk of 30-day unplanned readmission after discharge. However, neither score has been validated in the neurosurgical population. This study evaluated the HS and LI in the neurosurgical population as effective predictors for 30-day unplanned readmission.

Methods: We performed a prospective, cohort analysis of all consecutive adult patients admitted to the neurosurgical service between October 1, 2018 and May 1, 2019. Patient medical records were used to calculate HS and LI. HS defined groups as low risk (0-4), intermediate (5-6), and high (7-12); LI defined risk as low (1-4), moderate (5-9), and high (10-19). Data analysis used univariate and multivariate logistic regressions.

Results: The 1242 patients included 626 women (50.4%). The average age was 57.9 years, and most patients (86.5%) underwent surgery during their admission. In multivariate logistic regression, intermediate-risk HS was not predictive of 30-day readmission (odds ratio [OR], 1.04; 95% confidence interval [CI], 0.57-1.88; P = 0.53), whereas high-risk HS did predict readmission (OR, 2.87; 95% CI, 1.49-5.54; P = 0.002). Likewise, moderate-risk LI was not predictive of 30-day unplanned readmission or mortality (OR, 1.59; 95% CI, 0.88-2.85; P = 0.12); however, high-risk LI did predict unplanned readmission or mortality (OR, 2.58; 95% CI, 1.16-5.73; P = 0.02). Both HS and LI showed poor to moderate discrimination (C = 0.62 and 0.60, respectively).

Conclusions: A high-risk HS and high-risk LI were predictive of 30-day unplanned readmission. Although neither score is ideal for predicting moderate risk for 30-day unplanned readmission in neurosurgical patients, both have some predictiveness that may be clinically valuable.
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http://dx.doi.org/10.1016/j.wneu.2020.01.117DOI Listing
May 2020

Percutaneous Radiofrequency Ablation Is Ready for Prime Time in the Treatment of Colorectal Pulmonary Metastases.

Authors:
Joseph J Gemmete

Radiology 2020 Mar 14;294(3):696-697. Epub 2020 Jan 14.

From the Department of Radiology, Neurosurgery, Neurology, and Otolaryngology, Michigan Medicine, 1500 E Medical Center Dr, UH B1 328, Ann Arbor, MI 48109.

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http://dx.doi.org/10.1148/radiol.2020192558DOI Listing
March 2020

Scholarly Activities and Indices Among Academic Endovascular Specialists: A Comparative Analysis Between Interventional Radiologists and Vascular Surgeons.

Curr Probl Diagn Radiol 2021 Mar-Apr;50(2):132-136. Epub 2019 Oct 31.

Department of Radiology, Division of Interventional Radiology, University of Washington, Seattle, WA. Electronic address:

Purpose: To report scholarly metrics amongst academic endovascular specialists.

Material And Methods: Faculty pages identified interventional radiologists and vascular surgeons at academic institutions. Members were classified as assistant, associate, or full professors. Scopus was used to extract publication and citation records. Data extracted included: number of publications, number of citations, h-index, i-10 index, hc-index, m-quotient, e-index, and g-index.

Results: Two hundred seventy six interventional radiologists and 266 vascular surgeons were included. Mean publications for interventional radiology assistant, associate, and full professors were 17.81, 48.77, and 131.65 and the citation counts were 311.45, 1051.08, and 3981.71, respectively. Mean publications for vascular surgeon assistant, associate, and full professors were 24.00, 48.7, and 161.37 and the citation counts were 414.33, 1147.89, and 5747.00, respectively. Multivariable proportional odds model for interventional radiologists showed a positive correlation between the academic rank and publication count (c = 0.028), h-index (c = 0.090), i10-index (c = 0.014), hc-index (c = 0.052), e-index (c = 0.016), and g-index (0.037). There was a negative correlation between m-quotient (c = -1.745) and citations (c = -0.001) and academic rank. Multivariable proportional odds model for vascular surgeons showed a positive correlation between the academic rank and publication count (c = 0.037) and g-index (c = 0.083). There was a negative correlation between m-quotient (c = -2.232) and hc-index (c = -0.065) and academic rank.

Conclusion: Citation count and h-index are positively correlated while m-quotient is negatively correlated with academic performance for endovascular specialists.
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http://dx.doi.org/10.1067/j.cpradiol.2019.10.010DOI Listing
October 2021

Percutaneous Transesophageal Access for Enteral Feeding Tube Placement.

Cardiovasc Intervent Radiol 2020 Jan 21;43(1):155-161. Epub 2019 Aug 21.

Department of Radiology, Division of Vascular and Interventional Radiology, University of Michigan Health Systems, 1500 East Medical Center Drive, Ann Arbor, MI, 48109, USA.

Background: The purpose of this study was to describe our experience with percutaneous transesophageal enteral feeding tube placement when percutaneous gastrostomy tube placement is not feasible.

Materials And Methods: A retrospective review was performed from July 2018 to March 2019. Thirteen patients (9 females, 4 males), (age range 22-80 years; mean age, 55 years; mean body mass index of 24.6) underwent placement of 14 percutaneous transesophageal enteral feeding tubes. Relative contraindications to standard gastrostomy tube placement included: prior gastric surgery (5 patients), severe contractures/large body habitus (2), abdominal mesh (1), high riding stomach (1), interposition of bowel (1), ascites (1), and refractory gastrostomy tract leak (1). Patients were evaluated for functionality of the tube, complications, and patients' satisfaction with physical examination at 24 h, review of electronic medical record and phone interviews at 1 month, and 3-month follow-up. Complications were classified according to the CIRSE guidelines.

Results: Technical success rate was 100% with placement of seven percutaneous transesophageal gastrostomy tubes and seven percutaneous transesophageal jejunostomy tubes. One patient underwent tube placement twice after dislodgement. At 3-month follow-up, two patients had died, one patient was lost to follow-up, and 11 patients had properly working tubes. No major complications occurred. Minor complication rate was 43% (6/14). Patient's satisfaction scores ranged from "poor" 2/11 (18%) or "neutral" 4/11 (36.4%) to "satisfied/very satisfied" 5/11 (45.3%).

Conclusion: Percutaneous transesophageal enteral feeding tube placement is feasible with a low complication rate. A majority of patients were either satisfied or neutral with the transesophageal enteral tube.
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http://dx.doi.org/10.1007/s00270-019-02315-5DOI Listing
January 2020

Neuroprotection for ischemic stroke in the endovascular era: A brief report on the future of intra-arterial therapy.

J Clin Neurosci 2019 Nov 17;69:289-291. Epub 2019 Aug 17.

Department of Neurosurgery, University of Michigan, Ann Arbor, MI, United States. Electronic address:

Mechanical thrombectomy is now at the forefront of the treatment of large vessel acute ischemic stroke (AIS). Selective intra-arterial (IA) access has opened a new avenue for neuroprotection in AIS that has the potential to maximize local benefit while minimizing systemic effects. On a cellular level, neuroprotective strategies are aimed at reducing inflammation and free-radical formation, maintaining blood-brain barrier fidelity, and preventing cellular death. Strategies under investigation include IA infusion of neuroprotective agents, IA administration of stem cells, and selective IA hypothermia. In this technical report, we briefly discuss pathologic mechanisms in AIS and highlight potential neuroprotective strategies that are administered selectively via the IA route.
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http://dx.doi.org/10.1016/j.jocn.2019.08.001DOI Listing
November 2019

Burnout among Interventional Radiologists.

J Vasc Interv Radiol 2020 Apr 22;31(4):607-613.e1. Epub 2019 Jul 22.

Cardiovascular and Interventional Radiology, Inova Alexandria Hospital, 4320 Seminary Road, Alexandria, VA 22304. Electronic address:

Purpose: To characterize burnout, as defined by high emotional exhaustion (EE) or depersonalization (DP), among interventional radiologists using a validated assessment tool.

Materials And Methods: An anonymous 34-question survey was distributed to interventional radiologists. The survey consisted of demographic and practice environment questions and the 22-item Maslach Burnout Inventory-Human Services Survey (MBI). Interventional radiologists with high scores on EE (≥ 27) or DP (≥ 10) MBI subscales were considered to have a manifestation of career burnout.

Results: Beginning on January 7, 2019, 339 surveys were completed over 31 days. Of respondents, 263 (77.6%) identified as male, 75 (22.1%) identified as female, and 1 (0.3%) identified as trans-male. The respondents were interventional radiology attending physicians (298; 87.9%), fellows (20; 5.9%), and residents (21; 6.2%) practicing at academic (136; 40.1%), private (145; 42.8%), and hybrid (58; 17.1%) centers. Respondents worked < 40 hours (15; 4.4%), 40-60 hours (225; 66.4%), 60-80 hours (81; 23.9%), and > 80 hours (18; 5.3%) per week. Mean MBI scores for EE, DP, and personal achievement were 30.0 ± 13.0, 10.6 ± 6.9, and 39.6 ± 6.6. Burnout was present in 244 (71.9%) participants. Identifying as female (odds ratio 2.4; P = .009) and working > 80 hours per week (odds ratio 7.0; P = .030) were significantly associated with burnout.

Conclusions: Burnout is prevalent among interventional radiologists. Identifying as female and working > 80 hours per week were strongly associated with burnout.
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http://dx.doi.org/10.1016/j.jvir.2019.06.002DOI Listing
April 2020

Aspiration Thrombectomy-Assisted Endovascular Retrieval of an Embolized Angio-Seal Device Causing Claudication.

Ann Vasc Surg 2019 Oct 8;60:476.e7-476.e11. Epub 2019 May 8.

Division of Interventional Radiology, Department of Radiology, University of California Los Angeles, Los Angeles, CA.

The Angio-Seal vascular closure device is used to reduce time to hemostasis after femoral artery puncture. Although rare, complications associated with Angio-Seal are significant, including infection, pseudoaneurysm formation, symptomatic femoral artery stenosis, and separation and embolization, leading to limb-threatening ischemia. This report describes Angio-Seal polymer anchor embolization to the tibioperoneal trunk successfully retrieved using the 8-French Indigo Aspiration System.
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http://dx.doi.org/10.1016/j.avsg.2019.02.047DOI Listing
October 2019

Intraoperative Proximal Left Pulmonary Artery Injury during Thoracotomy Salvaged with VIABAHN VBX Balloon-Expandable Endoprosthesis.

J Vasc Interv Radiol 2019 May;30(5):724-725

Department of Radiology, Division of Vascular and Interventional Radiology, University of Michigan Health Systems, 1500 E. Medical Center Dr., Ann Arbor, MI 48109. Electronic address:

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http://dx.doi.org/10.1016/j.jvir.2018.04.021DOI Listing
May 2019

Computed Tomography Myelosimulation Versus Magnetic Resonance Imaging Registration to Delineate the Spinal Cord During Spine Stereotactic Radiosurgery.

World Neurosurg 2019 02 26;122:e655-e666. Epub 2018 Oct 26.

Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan, USA.

Background: Underestimation of the spinal cord's volume or position during spine stereotactic radiosurgery can lead to severe myelopathy, whereas overestimation can lead to tumor underdosage. Spinal cord delineation is commonly achieved by registering a magnetic resonance imaging (MRI) study with a computed tomography (CT) simulation scan or by performing myelography during CT simulation (myelosim). We compared treatment planning outcomes for these 2 techniques.

Methods: Twenty-three cases of spine stereotactic radiosurgery were analyzed that had both a myelosim and corresponding MRI study for registration. The spinal cord was contoured on both imaging data sets by 2 independent blinded physicians, and Dice similarity coefficients were calculated to compare their spatial overlap. Two treatment plans (16 Gy and 18 Gy) were created using the MRI and CT contours (92 plans total). Dosimetric parameters were extracted and compared by modality to assess tumor coverage and spinal cord dose.

Results: No differences were found in the partial spinal cord volumes contoured on MRI versus myelosim (4.71 ± 1.09 vs. 4.55 ± 1.03 cm; P = 0.34) despite imperfect spatial agreement (mean Dice similarity coefficient, 0.68 ± 0.05). When the registered MRI contours were used for treatment planning, significantly worse tumor coverage and greater spinal cord doses were found compared with myelosim planning. For the 18-Gy plans, 10 of 23 MRI cases (43%) exceeded the spinal cord or cauda dose constraints when using myelosim as the reference standard.

Conclusions: Significant spatial, rather than volumetric, differences were found between the MRI- and myelosim-defined spinal cord structures. Tumor coverage was compromised with MRI-based planning, and the high spinal cord doses were a concern. Future work is necessary to compare thin-cut, volumetric MRI registration or MRI simulation with myelosim.
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http://dx.doi.org/10.1016/j.wneu.2018.10.118DOI Listing
February 2019
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