Flow Void Research Articles

Evolutionary multi-target neural network architectures for flow void analysis in optical coherence tomography angiography

Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality used to evaluate the retinal microvasculature. Recent advances in OCTA allows to visualize the blood flow within the choriocapillaris region, where a granular image is obtained showing a pattern of small dark regions, called flow voids (FVs). Given its relevance, numerous clinical studies have linked the changes in FVs distribution to multiple diseases. The granular structure of these images makes accurate labeling and segmentation difficult, which can be overcome by using a multi-target perspective. However, manually designing a neural architecture that can accurately predict all targets in a balanced way is a major challenge. In this work, we propose a novel methodology based on evolutionary multi-target optimized networks that, through a set of evolutionary operators, traverses a search space of architectures in a deep but efficient way. This methodology allows us to discover efficient and accurate multi-target architectures tailored to our problem, but which are also adaptable to other tasks due to their robustness. To validate and analyze our methodology and the discovered network model, we performed extensive experimentation with cases from a real clinical study, achieving better results than the state of the art and manually designed architectures.

Endoscopic treatment of patients with idiopathic hydrocephalus with extraventricular cisternal obstruction of the cerebrospinal tract

The possibility of developing extraventricular CSF pathways obstruction was demonstrated in the mid-20th century. The development of neuroimaging (mainly MRI) and endoscopic techniques made it possible to plan and perform minimally invasive surgeries in a narrow anatomical corridor and achieve the regression of neurological symptoms. Purpose of the study: to determine the effectiveness of endoscopic surgery for hydrocephalus due to idiopathic extraventricular CSF pathways obstruction. Materials and methods. Sixty-five patients with signs of extraventricular obstruction underwent examination and surgical treatment at the Center of Neurosurgery from 2007 to 2020. The preoperative Kiefer Scale score was 6.8±3.3 (0-15) points, and the Rankin Scale score — 2.2±1 (0-5) points. Endoscopic third ventriculocisternostomy was performed as the first operation in 42 (64.6 %) patients. Ventriculoperitoneal shunting was performed in 17 (26.1 %) patients. Six (9.2 %) patients were not operated on. Results. After endoscopic surgery, the condition of the patients significantly improved (p < 0.001) after 2 and 12 months. Complete or partial regression of symptoms was noted in 85 % of the patients 1 year after surgery. After shunt surgery, the trend was comparable. The only radiological parameter that changes and correlates with the patients’ condition is the position of the premammillary membrane and the flow void. The remaining indicators of the CSF system of the brain did not actually change. In all cases of the endoscopic surgery, an additional membrane conglomerate that corresponded to preoperative tomograms was found under the premammillary membrane. Conclusion. The high efficiency of endoscopic third ventriculocisternostomy allows recommending this technique as the primary one in patients with extraventricular CSF pathways obstruction, with the exception of cases of anatomy abnormalities of the third ventricular fundus area (short premammillary membrane in combination with a high-lying basilar bifurcation) and cisterns of the posterior cranial fossa base (narrow cisterns, whose dimensions do not allow inserting an endoscope under the premamillary membrane).

Computed tomography imaging characteristics of neck paragangliomas: A retrospective analysis

Background/Aim: Paragangliomas are rare neuroendocrine tumours arising from paraganglia of the autonomic nervous system. Computed to-mography (CT) imaging plays a crucial role in the evaluation and character-isation of neck paragangliomas. This retrospective study aimed to analyse the CT imaging features of neck paragangliomas to enhance diagnostic accuracy and delineate the radiological characteristics associated with these tumours. Methods: A retrospective review of CT imaging studies of patients diagnosed with neck paragangliomas from March 2021 to October 2023 was conducted. Imaging characteristics including tumour location, size, enhancement pattern, vascularity, calcifications, adjacent tissue involvement and relationship with surrounding structures were analysed. Results: A total of 87 patients with histologically confirmed neck paragangliomas were included in the study. CT imaging revealed typical findings of neck paragangliomas ie well-defined hyper-vascular masses with avid contrast enhancement, commonly located at the carotid bifurcation or along the carotid sheath. In addition, characteristic flow voids and the presence of feeding vessels were observed on CT angiography in a significant number of cases. The imaging analysis also identified calcifications and encasement of adjacent structures as frequent features of advanced stage paragangliomas. Conclusions: CT imaging of neck paragangliomas demonstrated consistent radiological features, including hypervascularity, contrast enhancement and distinct anatomic locations. Knowledge of these imaging characteristics is essential for accurate diagnosis and preoperative planning. Recognition of these features on CT imaging can aid in differentiating paragangliomas from other neck masses and facilitate appropriate management strategies.

Multimodal Retinal Imaging Reveals New Pathogenic Insights in Central Areolar Choroidal Dystrophy: A Case Series.

To describe novel imaging findings in a family affected by central areolar choroidal dystrophy (CACD). Case series with multimodal retinal imaging assessment. A 19-year-old asymptomatic woman was referred for bilateral macular defects of the retinal pigment epithelium (RPE). Blue-light autofluorescence (BAF) of her right eye revealed a speckled pattern in the macular area with a ring of decreased autofluorescence using near-infrared autofluorescence (NIR-AF). Multimodal assessment of her left eye disclosed a single parafoveal spot of decreased pigmentation that was clearly visible as hyper-autofluorescent using BAF and as hypo-autofluorescent using NIR-AF. Optical coherence tomography angiography (OCT-A) revealed several tiny areas of flow voids in correspondence of the RPE alterations of both eyes.Three family members were recently diagnosed with presumed age-related macular degeneration and demonstrated well-demarcated areas of RPE atrophy surrounded by yellowish deposits and a hypo-pigmented halo.Next-generation genetic analysis for inherited macular dystrophies was performed on the index case and the affected family members and revealed a p.Arg172Gln missense mutation in PRPH2 gene, leading to the diagnosis of CACD. Multimodal imaging can reveal new pathogenic insights in CACD. Of notice, NIR-AF and OCT-A are able to detect RPE hypopigmentation and choriocapillaris rarefaction, respectively, since the earliest stages of the disease.

Association between intratumoral flow void and intraoperative blood loss in metastatic spinal tumor surgery

Association between intratumoral flow void and intraoperative blood loss in metastatic spinal tumor surgery

Multiple dural arteriovenous fistulas showing isolated subcortical white matter T2 hyperintensity with gadolinium enhancement

We describe a 44-year-old man with a complaint of atonic seizures of the left upper limb, followed by generalized seizures. Brain MRI showed isolated juxtacortical white matter T2 hyperintensity with gadolinium (Gd) enhancement of the adjacent cortical gray matter and subcortical white matter in the right frontal convexity. Treatment with levetiracetam was effective for seizure suppression, and he had no other neurological abnormalities. Human leukocyte antigen typing revealed B54 and Cw1, which indicated the possibility of neuro-Sweet disease. However, a general examination, which included vital signs and eye and skin findings, was normal. A cerebrospinal fluid test showed a mild elevation in protein levels without pleocytosis and a normal range of interleukin-6. Electroencephalography showed intermittent slow waves without epileptic discharge in the bilateral temporal lobes. We detected subtle flow voids in the pia mater of the left frontal lobe, which suggested cerebrovascular disease, and specifically, the possibility of dural arteriovenous fistulas. Computed tomography angiography showed abnormally dilated perimedullary veins in the left frontal lobe. Cerebral angiography confirmed the existence of four dural arteriovenous fistulas, which included two retrograde leptomeningeal venous drainages in the right frontal cortical veins supplied by the anterior branch of the right middle meningeal artery. The other dural arteriovenous fistulas were retrograde leptomeningeal venous drainages in the left frontal cortical veins supplied by the anterior and posterior convexity branches of the left middle meningeal artery. The patient underwent successful endovascular embolization of all dural arteriovenous fistulas with Onyx injection. A follow-up MRI showed gradual improvement of the T2 hyperintensity and Gd enhancement. He remained seizure-free for 2 years following endovascular embolization.

A giant infiltrating angiolipoma of the thigh: a case report

Background: Common vascular lipoma variants, such as angiolipoma, comprise 5–17% of all lipomas. They are categorized into two types: noninfiltrating and rare, deeper infiltrating forms that affect deep soft tissues and skeletal muscle. Young adults with the noninfiltrating type typically have it on their trunk and extremities, most frequently on the forearm. The World Health Organization (WHO) has identified deep infiltrating angiolipomas as intramuscular hemangiomas. The purpose of this case report was to describe a unique instance of a giant thigh angiolipoma that had infiltrated. Case report: A 9-year-old boy patient complained of a lump on the left thigh that was felt about 3 years ago. The lump has grown larger and painful in the last 6 months. He had no history of illness related to her current lump complaint of the thigh. In addition, he also denied any history of trauma. Magnetic Resonance Imaging (M.R.I.) displays hyperintense heterogeny mass with fat and flow void components on T1WI/T2WI/T2STIR. Histopathology signifies mature fat cells that penetrate the surrounding blood vessels, which are accompanied by fibrous connective tissue, indicating an intramuscular-infiltrating angiolipoma. Conclusion: We present a unique instance of a giant infiltrating thigh angiolipoma. Since angiolipoma is an uncommon histological type of giant lipoma, it should be considered in the differential diagnosis.

Flow Void Analysis Using Different Thresholding Methods on a Choriocapillaris Optical Coherence Tomography Angiography Image Complemented with a Structural En Face Image.

To investigate the flow characteristics using different thresholding methods on a choriocapillaris optical coherence tomography angiography (OCTA) image complemented with a structural En Face image. The 42 choriocapillaris OCTA images from healthy subjects were obtained with swept-source OCTA device and the 3 × 3-mm area OCTA images were processed with ImageJ. Using a raw choriocapillaris OCTA image and structural En Face image, we adjusted the different structural signal intensity. Then, the raw images and adjusted images were binarized with a global threshold and an auto local threshold using the Phansalkar method at 1- or 2-intercapillary distance. Then, the mean area, number, and size of the flow void, were compared among the images using different thresholding methods. Mean flow void area, number, and size were different according to the different binarization method both in raw and adjusted images (all p < 0.001). The mean flow void area analyzed with global threshold method were well correlated with those with auto local threshold method both in raw and adjusted images (all intraclass correlations, >0.929). Flow void features varied according to the different binarization methods but showed good correlation. The flow void characteristics according to the different binarization methods should be considered for the analysis of the choriocapillaris OCTA images complemented with a structural En Face image.

Smooth muscle tumours of the uterus: MR imaging malignant predictive features-a 12-year analysis in a referral hospital in Portugal.

To evaluate the magnetic resonance imaging (MRI) features that may help distinguish leiomyosarcomas from atypical leiomyomas (those presenting hyperintensity on T2-W images equal or superior to 50% compared to the myometrium). The authors conducted a retrospective single-centre study that included a total of 57 women diagnosed with smooth muscle tumour of the uterus, who were evaluated with pelvic MRI, between January 2009 and March 2020. All cases had a histologically proven diagnosis (31 Atypical Leiomyomas-ALM; 26 Leiomyosarcomas-LMS). The MRI features evaluated in this study included: age at presentation, dimension, contours, intra-tumoral haemorrhagic areas, T2-WI heterogeneity, T2-WI dark areas, flow voids, cyst areas, necrosis, restriction on diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) values, signal intensity and heterogeneity after contrast administration in T1-WI, presence and location of unenhanced areas. The association between the MRI characteristics and the histological subtype was evaluated using Chi-Square and ANOVA tests. The MRI parameters that showed a statistically significance correlation with malignant histology and thus most strongly associated with LMS were found to be: irregular contours (p < 0.001), intra-tumoral haemorrhagic areas (p = 0.028), T2-WI dark areas (p = 0.016), high signal intensity after contrast administration (p = 0.005), necrosis (p = 0.001), central location for unenhanced areas (p = 0.026), and ADC value lower than 0.88 × 10-3 mm2/s (p = 0.002). With our work, we demonstrate the presence of seven MRI features that are statistically significant in differentiating between LMS and ALM.

Localization of spinal dural arteriovenous fistulas from the spatial relationships of perimedullary vessels on standard MRI.

The goal in this study was to explore the spatial relationship of perimedullary vessels visualized on MRI to localize the side and the site of spinal dural arteriovenous fistula (SDAVF). A retrospective analysis of 30 consecutive patients diagnosed with SDAVF on MRI was undertaken. Two experienced reviewers blinded to all reports and angiographic images analyzed T2-weighted as well as postcontrast T1-weighted sequences. A focal prominent zone of perimedullary vessels with lateralization to one side in the thecal space was evaluated to locate the side and the site of the fistula. Spinal digital subtraction angiography served as the gold standard technique. Good interrater agreement (κ = 0.77) was shown for the diagnosis of SDAVF with perimedullary vessels on T2-weighted MRI. Flow voids on T2-weighted MRI demonstrated a sensitivity of 1.0 (95% CI 1.0-1.0) and an accuracy of 0.87 (95% CI 0.79-0.95) to identify the presence of fistula. The flow voids on T2-weighted MRI also demonstrated 0.88 (95% CI 0.71-1.03) sensitivity and 0.81 (95% CI 0.70-0.92) accuracy to identify the side of SDAVF. Furthermore, flow voids on T2-weighted MRI showed 0.87 (95% CI 0.71-1.03) sensitivity and 0.87 (95% CI 0.79-0.95) accuracy to identify the site of SDAVF within 3 vertebral levels above or below the actual site. Area under the receiver operating characteristic curve demonstrated significant results (0.87 [95% CI 0.73-1.0]; p < 0.001) for flow voids on T2-weighted MRI to identify the site of shunts within 3 vertebral levels in the cranial or caudal direction. Spatial distribution of perimedullary vessels observed on standard MRI show promise to locate the side and the site of fistula in patients with SDAVF.

SS OCT and OCT-A Findings in Convalescent Inactive Vogt-Koyanagi-Harada Disease

ABSTRACT Purpose This study aimed to determine predictive factors for low final visual acuity in patients with inactive Vogt-Koyanagi-Harada (VKH) disease using Swept-source OCT and OCT-angiography (OCT-A). Methods We conducted a prospective longitudinal study, including 21 patients (42 eyes), who were followed up for the first 24 months after disease onset. Patients were included at the acute phase and subsequently treated. Sequential qualitative and quantitative changes in OCT and OCT-A were assessed. Analytical statistical methods were employed to determine predictive factors for final visual acuity. Results Structural alterations including focal parafoveal outer nuclear layer atrophy, ellipsoid zone disruption, interdigitation zone disruption, and irregular and thickened retinal pigment epithelium line were observed in 57.1% of eyes at month 3, with no significant improvement over time. The presence of flow voids at months 6, 12, and 24 was significantly associated with low final visual acuity. Serous retnal detachment at presentation emerged as an independent risk factor for structural changes detected by SS-OCT during the first 2 years of the disease. Optic disc edema was predictive factor for both structural SS-OCT and OCT-A changes. Conclusion This study underscores the importance of monitoring flow voids to predict final visual acuity and highlights the impact of serous retinal detachment at presentation on structural changes in patients with inactive VKH disease.

Abstract 081: Clinical Presentation and Treatment of 26 Spinal Epidural Arteriovenous Fistulas: A Single Center Experience

Introduction Spinal epidural arteriovenous fistulas (SEAVFs) are rarely diagnosed vascular malformations that can cause spinal cord compression and congestive myelopathy. Methods This is a single center, retrospective case series of patients with SEAVF who underwent observation or treatment at UCLA medical center from 1993 to 2023. Results A total of 26 patients were found to have a SEAVF at UCLA from 1993 to 2023. The median age at treatment was 59 years (range 4 months to 91 years). 16 of 26 patients (55.2%) were male. 12 were located in the cervical spine, 2 in the thoracic spine, 11 in the lumbar spine, and 1 in the sacral spine. Sacral, lumbar, and thoracic SEAVFs demonstrated a strong male predominance (12 of 14, 85.7%), while cervical SEAVFs were more common in women (8 of 12, 66.7%). The median duration of symptoms prior to treatment was 6.5 months (range 1 day to 8 years). Possible triggers included prior spinal surgery (n=3), turning neck (n=1), trauma to the neck (n=1), lifting a heavy box (n=1), prolonged period of bending over (n=1). The remaining patients did not have any particular trigger. All patients with lumbar and thoracic SEAVFs (except the 3‐month‐old) demonstrated flow voids and cord edema. Patients with cervical SEAVF did not demonstrate cord edema and only 5 of 12 explicitly mentioned flow voids. 22 patients were treated strictly endovascularly, 1 patient endovascularly and then surgically, 1 patient surgically, and 2 patients refused treatment. No patients treated endovascularly experienced complications. 19 of 23 patients (82.6%) treated endovascularly received complete cure after the first treatment. 1 patient had a successful subsequent embolization 2 days later. Of the 3 other incomplete treatments, one patient received subsequent successful surgery, one patient was a 3‐month‐old patient with Parkes‐Weber syndrome who subsequently died of other medical issues, and one was lost to follow‐up. One patient underwent surgical treatment alone due to the feeding arteries being too small to catheterize and unfortunately experienced a failed surgery on the first attempt and developed a surgical site infection after the second successful attempt at treatment. Onyx was used in 10 cases (9 of 10 successful). 2 cases treated with NBCA were unsuccessful. Cervical and Sacral SEAVFs were treated successfully (mostly prior to 2006) with coils and/or detachable balloons. Conclusion SEAVF is a rare disease that can be treated effectively and safely with endovascular embolization in most cases. Pre‐operative MRI demonstrated abnormalities in all cases. We found a strong male predominance in our cohort.

Unveiling the Hidden: Early Manifestations of Extensive Macular Atrophy with Pseudodrusen-like appearance.

To describe novel microperimetry and imaging findings in two patients affected by extensive macular atrophy with pseudodrusen-like appearance (EMAP) without signs of retinal pigment epithelium (RPE) atrophy. Case series. Both patients underwent mesopic and dark-adapted two-color scotopic microperimetry, followed by multimodal imaging assessment including ultra-widefield photography, fundus autofluorescence (AF), high-resolution optical coherence tomography (Hi-Res OCT), OCT angiography and high-magnification module (HMM). Albeit normal visual acuity, both patients had a significant reduction of retinal sensitivity - especially under scotopic cyan conditions. One patient had macular pigment abnormalities, while the combination of blue and near-infrared AF modalities highlighted different patterns of pseudodrusen-like lesions.Of notice, Hi-Res OCT revealed a marked separation between the RPE and Bruch's membrane, containing a hyperreflective material with two different reflectivities. OCT angiography excluded the presence of macular neovascularization and documented several choriocapillaris flow voids. HMM images showed severe alteration of photoreceptors' mosaic in the perifovea. Our comprehensive assessment of two stage 1 EMAP patients revealed a predominant damage of perifoveal rods over areas of RPE-Bruch's membrane separation. These findings underscore the importance of basal laminar deposits in the initial stages of EMAP, contributing to a deeper understanding of its underlying mechanisms.

Abstract 093: Carotid Stump Syndrome: an Insidious Source of Recurrent Ischemic Strokes

Introduction Carotid stump syndrome (CSS) is a paradoxical phenomenon that occurs when there are repeated ischemic events in the carotid vascular territory despite demonstrated occlusion of the ipsilateral internal carotid artery (ICA). It is thought to be caused by turbulent blood flow in the patent stump of the occluded ICA creating microemboli which reach the brain through anastomotic channels and retrograde flow. We present a case of recurrent infarctions in setting of known ipsilateral ICA occlusion, who was diagnosed with carotid stump syndrome. Methods A male veteran in his 60s with a medical history of DVTs on apixaban, PVD, and ischemic stroke with residual right‐sided weakness, presented with worsening right‐sided weakness and difficulty with ambulation. Two months prior to the presentation he was diagnosed with acute infarcts in left frontal, parietal, and temporal lobes due to thromboembolism from left ICA occlusion. On presentation his neurological exam revealed right‐sided hemiparesis. MRI brain showed multiple acute and chronic cortical and subcortical infarcts in the left frontotemporoparietal lobes and lack of flow void in the left distal ICA. To further evaluate the dynamics of blood flow patient underwent a cerebral angiogram which confirmed the diagnosis of complete occlusion of left ICA and demonstrated reconstitution of the intracranial ICA through retrograde filling via the ophthalmic artery and anastomotic branches with the internal maxillary artery (IMax). For secondary prevention he was started on statin and aspirin while his home Apixaban was continued. Surgical and endovascular treatment approaches were discussed but the patient declined any intervention. In his four months follow up clinic visit he had no further concerns of recurrent strokes or new symptoms. Results Carotid stump syndrome is a rare cause of cerebral and retinal ischemia; however, it must be considered in patients with recurrent ischemic strokes and chronic ipsilateral ICA occlusion. Due to the patent proximal, or perhaps in some cases distal, carotid stump, there’s turbulent flow and hence the thrombus formation can occur. Hemodynamic and embolic factors attribute towards the microembolization from the proximal carotid stump through the external carotid artery (ECA), into the facial artery and IMax and their distal branches which anastomose with the ophthalmic artery, causing the emboli to end up in the major branches of the carotid terminus. If a distal stump is symptomatic, then the microemboli can readily end up in the distal ICA branches. In addition to medical management with DAPT or anticoagulation and high intensity statin, our literature review supports endovascular or surgical interventions due to reportedly good outcomes. Interventional approaches may include ECA‐ICA stenting with a covered stent or stent‐assisted coil embolization of the proximal stump. Surgical procedures include an endarterectomy on the ipsilateral ECA or contralateral ICA to increase collateral circulation. ECA‐ICA bypass is another option. Conclusion Carotid stump syndrome is a rare and underrecognized cause of recurrent ischemic strokes, though it is a potentially treatable entity. The therapeutic goals include medical management along with endovascular or surgical treatment whenever possible.

Choroidal features in non-neovascular and neovascular pachychoroid diseases.

To evaluate choroidal findings on multimodal imaging in eyes within pachychoroid spectrum diseases and to compare quantitative and qualitative choroidal features between non-neovascular (NNV-PDS) and neovascular (NV-PDS) pachychoroid diseases. Retrospective cross-sectional study comparing between NV-PDS and NNV-PDS. All patients underwent multimodal imaging including infracyanine green angiography (IFCGA) and swept source optical coherence tomography (OCT) and angiography (OCT-A). The following parameters were analyzed: subfoveal choroidal thickness (SFCT), choroidal vascular index (CVI), presence of pachyvessels and choroidal vascular interconnections (CVIC), presence of choroidal neovascularization and choriocapillaris density. Of the 87 eyes included in the study, 63 eyes (73%) had NNV-PDS and 24 eyes (27%) had NV-PDS. Mean SFCT and CVI were significantly higher in NNV-PDS group (p = 0.01; p = 0.022). Pachyvessels were more diffusely distributed in NNV-PD group and more focally distributed in NV-PDS group (p = 0.029). CVIC were more frequently noted in NV-PDS group (p = 0.024). A higher CVI was associated to a thicker choroid (p < 0.001), with significant negative correlations between the presence of CVIC and both SFCT (p = 0.015) and CVI (p = 0.002). We also observed a lower choriocapillaris vascular density and higher number of choriocapillaris flow voids in eyes with NNV-PDS (p = 0.24; p = 0.61). NNV-PDS eyes had a significantly thicker SFCT, higher CVI and a lower rate of detected CVIC than eyes with NV-PDS. These highlighted choroidal vascular changes might lead to a better understanding of pachychoroid disease pathophysiology. More frequently observed in NV-PDS group, CVIC are believed to assess the development of vortex vein anastomoses as a remodelling process for vascular decongestion.

Imaging Features of Alveolar Soft Part Sarcoma: Single Institution Experience and Literature Review.

Alveolar soft part sarcoma (ASPS) is an extremely rare and aggressive soft-tissue sarcoma (STS) subtype with poor prognosis and limited response to radiation therapy and chemotherapy. Prompt recognition and referral to sarcoma centers for appropriate management are crucial for patients' survival. The purpose of this study was to report ASPS pre-treatment imaging features and to examine the existing literature on this topic. Twelve patients (7 women, 5 men-mean age 27.1 ± 10.7 years) were included from our single-center experience. Ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) available were reviewed according to an analysis grid incorporating features from the latest research on STS. Clinical, histological, and outcome data were collected. MRI was available in 10 patients (83.3%), US in 7 patients (58.3%), and CT in 3 patients (25%). Mean longest tumor diameter was 7.6 ± 2.9 cm, and all tumors were deeply seated. Large peritumoral feeding vessels were systematically found and identified on ultrasonography (7/7), MRI (10/10), and CT (3/3). US revealed a well-defined heterogeneous hypoechoic pattern, with abundant flow signals in all patients (7/7). In all patients, MRI showed mildly high signal intensity (SI) on T1-WI and high SI on T2-WI and peritumoral edema. Moreover, flow-voids (due to arteriosus high-flow) into the peritumoral/intratumoral feeding vessels were detected in the MRI fluid-sensitive sequences of all patients. At baseline, whole-body contrast-enhanced CT revealed metastases in 8/12 (66.7%) patients. A pre-treatment longest diameter > 5 cm was significantly associated with distant metastases at diagnosis (p = 0.01). A maximum diameter > 5 cm represents a risk of metastatic disease at diagnosis (odds ratio = 45.0000 (95% CI: 1.4908-1358.3585), p = 0.0285). In the comprehensive literature review, we found 14 articles (case series or original research) focusing on ASPS imaging, with a total of 151 patients included. Merging our experience with the data from the existing literature, we conclude that the hallmark of ASPS imaging at presentation are the following characteristics: deep location, a slight hyperintense MRI SI on T1-WI and a hyperintense SI on T2-WI, numerous MRI flow voids, high internal vascularization, and large peritumoral feeding vessels.

Surgical aspects of classification and neuroimaging characteristics of idiopathic hydrocephalus in adults

Background. Hydrocephalus can be developing by a traumatic brain injury, intracranial hemorrhage, tumor, meningitis of congenital malformation of the central nervous system. When the cause of the hydrocephalus is unclear it is supposed as idiopathic hydrocephalus. The most important classification features are the etiology and level of CSF obstruction. The classification was improved and developed with diagnostic and surgical methods simultaneously. Currently, the neurosurgeons have the possibility for usage of various methods and techniques of surgical treatment with their advantages and disadvantages. Systematization of radiological parameters is necessary to make a decision about the type of the surgery.Aim. To analyze and systematize the neuroimaging characteristics of various forms of idiopathic hydrocephalus in adults, to assess the possible classification of idiopathic hydrocephalus.Materials and methods. Between October 2011 and March 2021 290 patients with idiopathic adult hydrocephalus were operated at the N.N. Burdenko National Medical Research Center of Neurosurgery of the Ministry of Health of Russia: onset of symptoms in adulthood; no indications of the etiology of hydrocephalus and congenital hydrocephalus. The age of the patients was 50 ± 18.2 (18–85) years. The magnetic resonance images of patients were evaluated for the size of the ventricles, condition of convexital and basal subarachnoid spaces, obstruction of the CSF pathways, and changes in the position of the premamillary membrane, septum pellucidum, the roof of the 3rd ventricle and the tonsils of the cerebellum, the size of the sella turcica, the angle of the corpus callosum. The frequency of each of these parameters is statistically estimated for each form of idiopathic hydrocephalus.Results. Aqueduct stenosis has become the most frequent form of idiopathic hydrocephalus. Hydrocephalus in obstruction of the foramen of Monroe, aqueduct, foramen of Magendie, and cisterns of the posterior cranial fossa was significantly more characteristic of young people (p &lt;0.05). Hydrocephalus with obstruction of convexital CSF spaces can be called hydrocephalus of the elderly (p &lt;0.001). Hydrocephalus without verified signs of occlusion CSF pathways occurs equally in all age groups. The FOHR index was significantly more important, and only in case of cisternal obstruction. Enlargement one or both lateral ventricles and flattening of the roof of the 3rd ventricle is characterized for Monro’s foramen obstruction (p &lt;0.001). The membrane at the outlet of the 4th ventricle and the absence of the “flow void” was typically only for patients with obstruction of the foramen of Magendie (p &lt;0.001). Ventral dislocation of the premamillary membrane was characteristic of obstruction of the cerebral aqueduct, the foramen of Magendie, and cisterns of the posterior cranial fossa. Compression of the convexital CSF spaces occurred in case of obstruction of the aqueduct, the foramen of Magendie, but CSF spaces of the posterior cranial fossa – only with obstruction of the foramen of Magendie. Dilation of the 4th ventricle was significantly associated with obstruction of the foramen of Magendie and cisterns of the posterior cranial fossa (p &lt;0.05). DESH symptom was significantly associated with obstruction of convexital CSF spaces (p &lt;0.001). Additional membranes in the cisterns of the posterior fossa were found only in cases of cisternal obstruction (p &lt;0.001). Cerebellar tonsils herniation was observed with obstruction of the foramen of Monroe, cerebral aqueduct, and foramina of Magendie.Conclusion. Because of statistical analysis, general signs found in all types of hydrocephalus, and private ones, characterizing only specific signs of the type of the disease, both were found. The classification is logical and justified, it is well applicable in neurosurgical and radiological practice. It allows rational planning of diagnostic evaluation and treatment of patients. A modern magnetic resonance imaging protocol should include T2 scans (with “flow void”) and FIESTA/CISS scans in the required planes, axial FLAIR scans.

The value of 3D T2-weighted SPACE sequence in the differential diagnosis of spinal arteriovenous fistula and acute transverse myelitis.

Spinal arteriovenous fistulas (SAVF) was often neglected and misdiagnosed as acute transverse myelitis (ATM) due to its insidious onset and non-specific clinical symptoms. This study aims to investigate the differential diagnostic value of high-resolution T2-weighted volumetric sequence (3D sampling perfection with application-optimized contrasts using different flip-angle evolutions [SPACE]) in patients with SAVF and ATM. Retrospectively analyzed the clinical and radiological findings of 32 SDAVF patients and 32 ATM patients treated at our institutions from May 2018 to January 2023. They all underwent conventional spinal MRI and T2-SPACE examination, compared their performance in identifying lesions, to estimate the value of T2 SPACE sequence in the diagnosis of SAVF and ATM patients. The clue of cauda equina area change (CEAC) in conventional MRI and T2-SPACE sequences is specific for the diagnosis of SAVF. The diagnostic model composed of perimedullary flow voids (PFV) and CEAC has good diagnostic performance (AUCMRI = 0.95; AUCSPACE = 0.935). Compared with conventional MRI, the T2-SPACE sequence has a higher detection rate, sensitivity, and negative predictive value for PFV and CEAC in SAVF patients, but lower specificity and positive predictive value. In T2-SPACE images, there are significant differences in the distribution range, quadrant, and maximum diameter of PFV vessels between SAVF and ATM patients. Moreover, T2-SPACE sequence can determine the site of fistula in most SAVF patients preferably, and the inter-rater agreement was good in the assessment of the fistula. The CEAC is a new and useful clue for the diagnosis of thoracolumbar SAVF. And T2-SPACE sequence can more intuitively observe the lesions of SAVF, has good differential diagnostic value for SAVF and ATM patients.

The dynamic contrast enhanced-magnetic resonance imaging and diffusion-weighted imaging features of alveolar soft part sarcoma.

Alveolar soft part sarcoma (ASPS) is a rare type of soft tissue sarcoma that predominantly affects adolescents and young adults. Early diagnosis of ASPS is crucial for optimal therapeutic planning and improving prognosis, but its diagnostic features are not well delineated. This study aimed to retrospectively analyze the imaging features of ASPS with an emphasis on the dynamic contrast-enhanced-magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) findings to identify imaging findings that might suggest the diagnosis to radiologists. The imaging features of 34 patients with pathologically proven limb ASPS were retrospectively analyzed. A total of 23 underwent DCE-MRI, and 12 underwent DWI. Among the 34 cases of ASPS, 31 tumors were in the lower extremities, and 3 were in the upper extremities. The maximum tumor diameters ranged from 3.0 to 19.4 cm (mean, 8.7±3.96 cm). A total of 28 cases had well-defined borders. The masses demonstrated heterogeneous high signal intensity on T2-weighted imaging (T2WI) and the fat-suppressed (FS) T2WI sequence and slight hyperintensity on T1-weighted imaging (T1WI). A total of 25 lesions had thin hypointense bands on T1WI and T2WI. Intra- and peri-tumoral tubular areas of flow void were exhibited on both T1WI and T2WI in all cases. A total of 12 cases showed a high signal on DWI, and the mean apparent diffusion coefficient (ADC) value was (0.86±0.07)×10-3 mm2/s [range, (0.6-1.4)×10-3 mm2/s]. Persistent remarkable enhancement of the lesion was displayed on contrast-enhanced scans. The time-intensity curves (TICs) of 23 masses showed early arterial enhancement and slow washout of contrast. ASPS most commonly presents in the lower extremities of adolescents or young adults. Hyperintense T1WI, T2WI, and DWI signals, low ADC, flow voids, early arterial enhancement are frequent MRI features.

Two-phase flow structures in a helically coiled microchannel: An experimental investigation

At the microfluidic scale, the utilization of helically coiled channels (HCCs), also known as a spiral channel, for two-phase flow offers numerous advantages in various applications. Existing articles mainly focus on the macro-scale transport, examining secondary flows induced in curved channels. The increasing demand, however, for innovative miniature equipment for thermal energy management emphasizes the importance of comprehending gas–liquid micro-scale flow in curved channels. Unfortunately, despite a vast body of literature on this paradigm, there is still a lack of systematic investigations into the underlying facets of two-phase micro-scale transport in HCCs. To address this gap, our study conducted experiments on adiabatic two-phase air–water flow inside an up-flow helical micro-scale tube. The tube had a hydraulic diameter of 0.87 mm, a coil diameter of 50 mm, and a helical pitch of 20 mm. The primary aim was to explore the impact of centrifugal force on flow pattern, void fraction, and frictional pressure drop characteristics. Additionally, we carefully examined the phase separation phenomenon influenced by the secondary flows induced by the curved channel. In particular, we compared the gas-core flow pattern (either throat-annular flow or annular flow), void fraction, and frictional pressure drop obtained from our experiments on the helical tube with corresponding results based on straight micro-scale channel configurations for an Eötvös number of approximately 0.01. In summary, this study delves deep into the crucial aspects of two-phase micro-scale transport in HCCs, contributing to a better understanding of these systems for future advancements in micro-channel applications.