A new versatile MR-guided high-intensity focused ultrasound (HIFU) device for the treatment of musculoskeletal tumors.

Magnetic Resonance (MR) Imaging-guided High Intensity focused Ultrasound (MRgHIFU) is a non-invasive, non-ionizing thermal ablation therapy that is particularly interesting for the palliative or curative treatment of musculoskeletal tumors. We introduce a new modular MRgHIFU device that allows the ultrasound transducer to be positioned precisely and interactively over the body part to be treated. A flexible, MR-compatible supporting structure allows free positioning of the transducer under MRI/optical fusion imaging guidance. The same structure can be rigidified using pneumatic depression, holding the transducer rigidly in place. Targeting accuracy was first evaluated in vitro. The average targeting error of the complete process was found to be equal to 5.4 ± 2.2 mm in terms of focus position, and 4.7° ± 2° in terms of transducer orientation. First-in-man feasibility is demonstrated on a patient suffering from important, uncontrolled pain from a bone metastasis located in the forearm. The 81 × 47 × 34 mm3 lesion was successfully treated using five successive positions of the transducer, under real-time monitoring by MR Thermometry. Significant pain palliation was observed 3 days after the intervention. The system described and characterized in this study is a particularly interesting modular, low-cost MRgHIFU device for musculoskeletal tumor therapy.

Bilateral posterior cerebral artery territory infarction in a SARS-Cov-2 infected patient: discussion about an unusual case.

In time of SARS-Cov2 pandemic, neurologists need to be vigilant for cerebrovascular complications of Covid-19. We present a case of bilateral occipito-temporal infarction revealed by a sudden cortical blindness with haemorrhagic transformation after intravenous thrombolysis in a diabetic patient infected by Covid-19. Differential diagnoses are discussed in front of this unusual presentation and evolution.

Accuracy of a CT-Ultrasound Fusion Imaging Guidance System Used for Hepatic Percutaneous Procedures.

PURPOSE: To evaluate the accuracy of a fusion imaging guidance system using ultrasound (US) and computerized tomography (CT) as a real-time imaging modality for the positioning of a 22-gauge needle in the liver. MATERIALS AND METHODS: The spatial coordinates of 23 spinal needles placed at the border of hepatic tumors before radiofrequency thermal ablation were determined in 23 patients. Needles were inserted up to the border of the tumor with the use of CT-US fusion imaging. A control CT scan was carried out to compare real (x, y, z) and virtual (x', y', z') coordinates of the tip of the needle (D for distal) and of a point on the needle located 3 cm proximally to the tip (P for proximal). RESULTS: The mean Euclidian distances were 8.5 ± 4.7 mm and 10.5 ± 5.3 mm for D and P, respectively. The absolute value of mean differences of the 3 coordinates (|x' - x|, |y' - y|, and |z' - z|) were 4.06 ± 0.9, 4.21 ± 0.84, and 4.89 ± 0.89 mm for D and 3.96 ± 0.60, 4.41 ± 0.86, and 7.66 ± 1.27 mm for P. X = |x' - x| and Y = |y' - y| coordinates were <7 mm with a probability close to 1. Z = |z' - z| coordinate was not considered to be larger nor smaller than 7 mm (probability >7 mm close to 50%). CONCLUSIONS: Positioning errors with the use of US-CT fusion imaging used in this study are not negligible for the insertion of a 22-gauge needle in the liver. Physicians must be aware of such possible errors to adapt the treatment when used for thermal ablation.

Targetability of osteoid osteomas and bone metastases by MR-guided high intensity focused ultrasound (MRgHIFU).

PURPOSE: To retrospectively evaluate the suitability of MRgHIFU for osteoid osteomas (OOs) and bone metastases in patients who underwent minimally-invasive percutaneous thermal ablation. MATERIALS AND METHODS: One hundred and sixty-seven lesions (115 metastases and 52 OOs) treated percutaneously between October 2014 and June 2017 were retrospectively analyzed. Tumors were located in the spine or sacrum (54), pelvis (43), limbs (50), ribs (17) and sternum (3). Tumor volume, matrix, anatomical environment and need for protection of surrounding structures or consolidation were assessed. Cases were classified into three categories: (a) lesions suitable for MRgHIFU therapy alone; (b) lesions suitable for MRgHIFU if protection of surrounding structures and/or bone consolidation is performed; (c) lesions not suitable for MRgHIFU. RESULTS: Twenty-six (50%) of OOs were classified as suitable for MRgHIFU alone and 17 (32.7%) as suitable for MRgHIFU with hydro-dissection. Matrix of treatable OOs was sclerotic (19), lytic (15) or mixed (9), with mean volume 0.56 cm3. Forty-one (35.7%) of metastases were classified as suitable for MRgHIFU alone and 43 (37.4%) as suitable with hydro-dissection and/or consolidation. Matrix of metastases was sclerotic (13), lytic (37) or mixed (34), with mean volume 71.9 cm3. Mean depth of targetable lesions was 50.9 ± 28.4 mm. 97.7% of pelvic lesions and 94% of peripheral bone lesions were targetable by HIFU. 66.6% of spinal or sacral lesions were considered untreatable. CONCLUSION: MRgHIFU cannot be systematically performed non-invasively on bone tumors. Combination with minimally-invasive thermo-protective techniques may increase the number of eligible cases.

Bipolar radiofrequency ablation of aneurysm remnants after coil embolization can improve endovascular treatment of experimental bifurcation aneurysms.

OBJECTIVE Endovascular treatment of aneurysms may result in incomplete initial occlusion and aneurysm recurrence at angiographic follow-up studies. This study aimed to assess the feasibility and efficacy of bipolar radiofrequency ablation (RFA) of aneurysm remnants after coil embolization. METHODS Bipolar RFA was accomplished using the coil mass as 1 electrode, while the second electrode was a stent placed across the aneurysmal neck. After preliminary experiments and protocol approval from the Animal Care committee, wide-necked bifurcation aneurysms were constructed in 24 animals. Aneurysms were allocated to 1 of 3 groups: partial intraoperative coil embolization, followed by RFA (n = 12; treated group) or without RFA (n = 6; control group 1); or attempted complete endovascular coil embolization 2-4 weeks later (n = 6; control group 2). Angiographic results were compared at baseline, immediately after RFA, and at 12 weeks, using an ordinal scale. Pathological results and neointima formation at the neck were compared using a semiquantitative grading scale. RESULTS Bipolar RFA was able to reliably target the aneurysm neck when the coil mass and stent were used as electrodes. RFA improved angiographic results immediately after partial coiling (p = 0.0024). Two RFA-related complications occurred, involving transient occlusion of 1 carotid artery and 1 hemorrhage from an adventitial arterial blister. At 12 weeks, angiographic results were improved with RFA (median score of 0), when compared with controls (median score of 2; p = 0.0013). Neointimal closure of the aneurysm neck was better with RFA compared with controls (p = 0.0003). CONCLUSIONS Bipolar RFA can improve results of embolization in experimental models by selectively ablating residual lesions after coil embolization.

Cortical Thickness in Dementia with Lewy Bodies and Alzheimer's Disease: A Comparison of Prodromal and Dementia Stages.

OBJECTIVES: To assess and compare cortical thickness (CTh) of patients with prodromal Dementia with Lewy bodies (pro-DLB), prodromal Alzheimer's disease (pro-AD), DLB dementia (DLB-d), AD dementia (AD-d) and normal ageing. METHODS: Study participants(28 pro-DLB, 27 pro-AD, 31 DLB-d, 54 AD-d and 33 elderly controls) underwent 3Tesla T1 3D MRI and detailed clinical and cognitive assessments. We used FreeSurfer analysis package to measure CTh and investigate patterns of cortical thinning across groups. RESULTS: Comparison of CTh between pro-DLB and pro-AD (p<0.05, FDR corrected) showed more right anterior insula thinning in pro-DLB, and more bilateral parietal lobe and left parahippocampal gyri thinning in pro-AD. Comparison of prodromal patients to healthy elderly controls showed the involvement of the same regions. In DLB-d (p<0.05, FDR corrected) cortical thinning was found predominantly in the right temporo-parietal junction, and insula, cingulate, orbitofrontal and lateral occipital cortices. In AD-d(p<0.05, FDR corrected),the most significant areas affected included the entorhinal cortices, parahippocampal gyri and parietal lobes. The comparison of AD-d and DLB-d demonstrated more CTh in AD-d in the left entorhinal cortex (p<0.05, FDR corrected). CONCLUSION: Cortical thickness is a sensitive measure for characterising patterns of grey matter atrophy in early stages of DLB distinct from AD. Right anterior insula involvement may be a key region at the prodromal stage of DLB and needs further investigation.

Imaging-guided percutaneous cryotherapy of bone and soft-tissue tumors: what is the impact on the muscles around the ablation site?

OBJECTIVE: The objectives of our study were to evaluate the incidence of muscular injury after cryoablation of bone and soft-tissue tumors, to relate MRI findings to the size of the intramuscular ice ball, and to determine the clinical significance of postcryotherapy myositis. MATERIALS AND METHODS: Between January 2010 and October 2012, 24 bone and soft-tissue lesions (16 pelvic lesions, three shoulder lesions, and five paravertebral lesions) in 21 patients treated by imaging-guided percutaneous cryoablation and followed up with MRI were retrospectively analyzed. Muscular hyperintensity on T2 STIR images was graded as follows: grade 0, no myositis; grade 1, local myositis; grade 2, myositis in less than half of the volume of the muscle; or grade 3, myositis in half of the volume of the muscle or more. The presence of T2 STIR hyperintensity in the muscles surrounding the cryoablation site was correlated with the volume of the intramuscular ice ball. RESULTS: Muscular T2 STIR hyperintensity was observed in 87.5% of cases (grade 0 in 12.5%, grade 1 in 45.8%, grade 2 in 20.8%, and grade 3 in 20.8%). The volume of the intramuscular ice ball and grade of myositis (mean volume: grade 0, 2.8 cm(3); grade 1, 9.2 cm(3); grade 2, 17.1 cm(3); grade 3, 42.9 cm(3)) were positively correlated in the 24 lesions in the study cohort (r = 0.64, p < 0.001). Only two cases of myositis (grade 3) were symptomatic, and antiinflammatory drugs promoted pain resolution in both cases. CONCLUSION: Muscular injury around the cryoablation site is commonly observed and is correlated with the volume of the ice ball. When muscular injury around the cryoablation site causes pain, the symptoms differ from the initial tumoral pain and can be treated with antiinflammatory drugs.

Type A acute aortic dissection: why does the false channel remain patent after surgery?

PURPOSE: To understand why the false channel (FC) remains patent after surgery of type A acute aortic dissection (TAAAD). MATERIALS AND METHODS: Postoperative contrast-enhanced computed tomography scans of 129 patients operated for TAAAD were analyzed, and a color-Doppler ultrasound examination (CDUS) of the supra-aortic vessels (SAVs) was performed in 12 patients. RESULTS: The FC remained patent in 107 (82.9%) patients. The entry site was situated near the distal anastomosis in 43 (40.2%) patients and far from it in 44 (41.1%) patients. In 10 (9.35%) patients, an entry site was observed only in the SAVs. In 10 (9.35%) patients, no entry site was seen. Of the 12 patients explored with CDUS, a retrograde filling of the FC was observed in 11 patients. CONCLUSION: The frequent postoperative circulating aortic FC can be explained by the persistence of the primary entry tear, the presence of iatrogenic tears, and/or a retrograde filling in the SAVs.

Flow diversion of giant curved sidewall and bifurcation experimental aneurysms with very-low-porosity devices.

OBJECTIVE: Flow diverters (FDs) are increasingly used to treat difficult intracranial aneurysms. The objective of this study was to test whether treatment challenges posed by giant curved sidewall (cSW) and endwall bifurcation (EwB) aneurysms can be overcome with the use of very-low-porosity devices. METHODS: Large and giant EwB (n = 12) and cSW aneurysms (n = 5) were constructed in 17 dogs. EwB aneurysms were treated with 48 (n = 4), 64 (n = 4), or two overlapping 64-wire low-porosity devices (n = 4), whereas all cSW aneurysms were treated with single 64-wire devices. Angiographic results were recorded immediately and at 12 weeks before euthanasia. Pathologic specimens were photographed and neointimal coverage of devices measured and scored. RESULTS: By 12 weeks, 1 of 12 EwB and 1 of 5 cSW aneurysms were occluded. All other aneurysms were patent. Device-related arterial stenoses occurred in 13 of 17 animals, hemodynamically significant in two. All branches jailed by the FDs remained patent. There was a significant correlation between angiographic scores and the degree of neointima formation on the device (Rho = 0.527; P = 0.04). Failures of aneurysm occlusion could be explained by holes, sometimes barely visible, in the neointima that formed over FDs. CONCLUSION: Low-porosity FDs fail to reliably occlude experimental giant EwB and cSW aneurysms.

Endovascular treatment with flow diverters may fail to occlude experimental bifurcation aneurysms.

INTRODUCTION: Animal models may explain how stents and flow diverters (FDs) may succeed or fail to treat bifurcation aneurysms. METHODS: In vitro studies were designed to anticipate device deformations in bifurcations. Large, wide-necked bifurcation aneurysms were constructed in 21 animals and treated 4-8 weeks later using stents and FDs in various combinations, forming four main groups: parent artery to right branch flow diversion (RBFD, n = 6), parent artery to left branch flow diversion (LBFD, n = 6), Y flow diversion (YFD, n = 4), and compared with high-porosity Y-stenting (YHPS, n = 4). The results include immediate and follow-up angiography at 3 months, followed by grading of the extent of neointimal coverage of devices at pathology. RESULTS: In vitro, all braided devices showed varying porosities according to characteristic zones. FDs can be compacted to decrease porosities, but a limiting factor is the constant presence of a more porous transition zone. In vivo, 3/6 RBFD, 4/6 LBFD, and 2/4 YFD treated aneurysms had decreased in size by 3 months, while those treated with YHPS increased in size (P = 0.15). There was a significant correlation between device porosities and extent of neointimal coverage (r = 0.639, P = 0.002), and between porosities and angiographic evolution (r = -0.655, P = 0.002), but not between neointima formation and angiographic evolution (r = -0.278, P = 0.235). Failures could be explained in all cases by the presence of leaks or holes in the neointima at the level of the transition zones. CONCLUSION: FDs did not successfully treat most bifurcation aneurysms, at least in this animal model.

Stents and flow diverters in the treatment of aneurysms: device deformation in vivo may alter porosity and impact efficacy.

INTRODUCTION: High-porosity (HP) and flow-diverting (FD) stents are increasingly used to treat intracranial aneurysms. In vivo device deformations and their impact on the porosity of the segment of device lying over the aneurysm neck remain inadequately characterized. METHODS: Porosities of different braided FDs were studied in straight and 90° curved glass tubes. In vivo, 11 experimental lateral wall aneurysms were treated with FD (n = 7) or HP (n = 4) stents. At 3 months, the segment of FDs and HP stents over the aneurysm neck was analyzed, paying attention to changes in device diameter, metallic porosity, and neointimal closure of pores over the aneurysm or branch ostia. Device deformations were reproduced with benchtop experiments. RESULTS: In 90° curved tubes, FD porosity was higher (P = 0.025) and pore density was lower (P = 0.01) on convex compared to concave surfaces, but variations remained within 5-10 %. After in vivo deployment, a spindle-shaped deformation of FDs occurred, with focal expansion at the level of the aneurysm neck (P = 0.004). This deformation translated into an accordion-like distribution of stent struts across the aneurysm neck, where porosity was not uniform. The midsection of the aneurysm ostium had more metal coverage than adjacent ostial areas (P = 0.002). Mean porosity over the aneurysm neck was 78 ± 9.4 and 32.6 ± 12.1 % for HP and FD stents, respectively (P = 0.008), decreasing to 13.0 ± 10.1 and 1.4 ± 0.6 % (P = 0.022) following neointimal coverage, respectively. Spindle-shaped deformations and accordion effects were reproduced with benchtop manipulations; fluctuations in porosity and diameter changes correlated closely (R = 0.81; P = 0.005). CONCLUSION: Alterations in porosity may occur following in vivo implantation.

Flow diversion to treat aneurysms: the free segment of stent.

PURPOSE: Flow diverters (FDs) have led to spectacular results in otherwise untreatable aneurysm cases, but complications can occur. There is a pressing need to study factors that might predict their safety and efficacy. METHODS: The anatomical constraints that may impact on the ability of FDs to redirect blood flow and provide a scaffold for neointima formation across the aneurysm or branch ostia are explored and classified. A nomenclature is needed to identify the key factors that should be taken into account before contemplating the use of FDs in clinical aneurysms, and that should be reproduced in experimental models, if they are to guide safe clinical use. RESULTS: The free stent segment (FSS), the portion of the device that covers an aneurysm or branch origin, dictates whether aneurysms or branches will remain patent. Three levels of increasing complexity must be taken into account to anticipate what will occur at the FSS level. (1) Virtual models can provide basic principles; (2) in vitro studies allow testing FSS deformations that may occur in various anatomical circumstances and impact on efficacy and safety; (3) but only in vivo studies can provide key information on neointimal closure following implantation that will differentiate success from failure. CONCLUSIONS: A nomenclature is necessary to determine the optimal or suboptimal conditions for FDs and to design the virtual, in vitro and in vivo studies that will allow a better understanding of the factors involved in the success or failure of this novel treatment.

Flow diverters failing to occlude experimental bifurcation or curved sidewall aneurysms: an in vivo study in canines.

OBJECT: Flow diverters (FDs) are increasingly used to treat complex intracranial aneurysms, but preclinical studies that could guide clinical applications are lacking. The authors designed a modular aneurysm model in canines to address this problem. METHODS: Three variants of one modular aneurysm model were constructed in 21 animals. Sidewall (n=5), curved sidewall (n=5), and end-wall bifurcation (n=7) aneurysms were treated with prototype 36-wire FDs. Four more end-wall bifurcation aneurysms were treated with prototype 48-wire lower-porosity FDs. Angiographic results postimplantation and at 3 months were scored with an ordinal scale. Animals were euthanized at 3 (n=17) or 6 (n=3) months, and the FD covering the aneurysm ostium was photographed to analyze metallic porosity and amount of neointima formation. RESULTS: Straight sidewall aneurysms were better occluded than curved sidewall and end-wall bifurcation aneurysms at the 3-month angiography follow-up (p=0.010). Flow diverters failed to occlude curved sidewall aneurysms (n=0/5) and all but one (n=1/7) end-wall bifurcation aneurysm. Angiographic results were no better (n=0/4) using a 48-wire FD (p=0.788). Branches jailed by the FD (n=16) remained patent in all cases. Metallic porosity was decreased (p=0.014) and neointimal closure of the aneurysm ostium was more complete (p=0.040) in sidewall aneurysms than in curved or bifurcation variants of the model. CONCLUSIONS: Flow diverters may succeed in treating straight sidewall aneurysms, but the same device repeatedly fails to occlude curved sidewall and end-wall bifurcation aneurysms. In vivo studies can be designed to test basic principles that, once validated, may serve to guide clinical use of new devices.

Primary intracranial extra-axial and supratentorial atypical rhabdoid tumor.

An atypical teratoid/rhabdoid tumor of the central nervous system is an aggressive infantile embryonal neoplasm, usually presenting as an infratentorial and intraparenchymatous lesion. We report on magnetic resonance imaging findings of a 22-month-old boy with a biopsy-proven primary rhabdoid tumor, presenting as a single intracranial supratentorial extra-axial mass. Based on the patient's age and imaging features (perfusion, diffusion magnetic resonance imaging, and magnetic resonance spectroscopy), a diagnosis of atypical teratoid/rhabdoid tumor was more accurate than diagnoses of meningioma and primitive neuroectodermal tumor. Although this entity is relatively rare, it should be considered in the differential diagnosis of dural-based, space-occupying central nervous system lesions.

An acute ischemic stroke secondary to sphenoid sinusitis.

Acute isolated sphenoid sinusitis is a relatively uncommon entity. Because its symptoms and clinical findings are nonspecific, it can be easily misdiagnosed. Left unrecognized and untreated, it can lead to several well-known and severe complications, including meningitis, cerebral abscess, cavernous sinus thrombosis, and epidural or subdural empyema. We report the case of a 28-year-old woman with acute sphenoid sinusitis complicated by ischemic stroke in the left caudate nucleus, lentiform nucleus, and posterior part of the internal capsule. The stroke was diagnosed on magnetic resonance imaging. Also, magnetic resonance angiography showed a narrowing of the internal carotid artery and a narrowing of the first part of the left anterior and middle cerebral arteries (A1 and M1 segments). The patient was treated with medical therapy, including antibiotics, and surgical drainage of the sphenoid sinus via an endoscopic approach. Her outcome was good, and she experienced minimal neurologic sequelae. We discuss the possible explanations for this rare complication.

Internal carotid false aneurysm after thermocoagulation of the gasserian ganglion.

OBJECTIVE: To identify petrous internal carotid bleeding aneurysm as a complication of gasserian ganglion thermocoagulation. PATIENTS: A single case presenting with epistaxis and otorrhagia 1 month after gasserian ganglion thermocoagulation in the treatment of refractory trigeminal neuralgia. INTERVENTION(S): Gasserian ganglion thermocoagulation, computed tomographic scan, and angiocomputed tomographic scan revealing petrous internal carotid ruptured aneurysm and internal carotid embolization. MAIN OUTCOME MEASURE(S): Radiologic diagnosis of the vascular injury after gasserian ganglion thermocoagulation. RESULTS: Radiologic identification of ruptured internal carotid artery as the cause of simultaneous epistaxis and otorrhagia. CONCLUSION: Gasserian ganglion thermocoagulation may cause aneurysm and rupture of the petrous portion of the internal carotid artery.