Imaging of Adult Malignant Soft Tissue Tumors of the Spinal Canal: A Guide for Spine Surgeons.

BACKGROUND: Malignant soft tissue spinal canal tumors compromise 20% of all spinal neoplasms. They may be primary or metastatic lesions, originating from a diverse range of tissues within and surrounding the spinal canal. These masses can present as diverse emergencies such as secondary cauda equina syndrome, vascular compromise, or syringomyelia. Interpretation of malignant soft tissue spinal canal tumors imaging is an essential for non-radiologists in the setting of emergencies. This task is intricate due to a great radiologic pattern overlap among entities. METHODS: We present a step-by-step strategy that can guide nonradiologists identify a likely malignant soft tissue lesion in the spinal canal based on imaging features, as well as a review of the radiologic features of malignant soft tissue spinal canal tumors. RESULTS: Diagnosis of soft tissue spinal canal malignancies starts with the identification of the lesion's spinal level and its relationship to the dura and medulla. The second step consists of characterizing it as likely-malignant based on radiological signs like a larger size, ill-defined margins, central necrosis, and/or increased vascularity. The third step is to identify additional imaging features such as intratumoral hemorrhage or cyst formation that can suggest specific malignancies. The physician can then formulate a differential diagnosis. The most encountered malignant soft tissue tumors of the spinal canal are anaplastic ependymomas, anaplastic astrocytomas, metastatic tumors, lymphoma, peripheral nerve sheath tumors, and central nervous system melanomas. A review of the imaging features of every type/subtype of lesion is presented in this work. Although magnetic resonance imaging remains the modality of choice for spinal tumor assessment, other techniques such as dynamic contrast agent-enhanced perfusion magnetic resonance imaging or diffusion-weighted imaging could guide diagnosis in specific situations. CONCLUSIONS: In this review, diagnostic strategies for several spinal cord tumors were presented, including anaplastic ependymoma, metastatic spinal cord tumors, anaplastic and malignant astrocytoma, lymphoma, malignant peripheral nerve sheath tumors , and primary central nervous system melanoma. Although the characterization of spinal cord tumors can be challenging, comprehensive knowledge of imaging features can help overcome these challenges and ensure optimal management of spinal canal lesions.

Style Transfer-assisted Deep Learning Method for Kidney Segmentation at Multiphase MRI.

Purpose: To develop and validate a semisupervised style transfer-assisted deep learning method for automated segmentation of the kidneys using multiphase contrast-enhanced (MCE) MRI acquisitions. Materials and Methods: This retrospective, Health Insurance Portability and Accountability Act-compliant, institutional review board-approved study included 125 patients (mean age, 57.3 years; 67 male, 58 female) with renal masses. Cohort 1 consisted of 102 coronal T2-weighted MRI acquisitions and 27 MCE MRI acquisitions during the corticomedullary phase. Cohort 2 comprised 92 MCE MRI acquisitions (23 acquisitions during four phases each, including precontrast, corticomedullary, early nephrographic, and nephrographic phases). The kidneys were manually segmented on T2-weighted images. A cycle-consistent generative adversarial network (CycleGAN) was trained to generate anatomically coregistered synthetic corticomedullary style images using T2-weighted images as input. Synthetic images for precontrast, early nephrographic, and nephrographic phases were then generated using the synthetic corticomedullary images as input. Mask region-based convolutional neural networks were trained on the four synthetic phase series for kidney segmentation using T2-weighted masks. Segmentation performance was evaluated in a different cohort of 20 originally acquired MCE MRI examinations by using Dice and Jaccard scores. Results: The CycleGAN network successfully generated anatomically coregistered synthetic MCE MRI-like datasets from T2-weighted acquisitions. The proposed deep learning approach for kidney segmentation achieved high mean Dice scores in all four phases of the original MCE MRI acquisitions (0.91 for precontrast, 0.92 for corticomedullary, 0.91 for early nephrographic, and 0.93 for nephrographic). Conclusion: The proposed deep learning approach achieved high performance in kidney segmentation on different MCE MRI acquisitions.Keywords: Kidney Segmentation, Generative Adversarial Network, CycleGAN, Convolutional Neural Network, Transfer Learning Supplemental material is available for this article. Published under a CC BY 4.0 license.

The burden of Hepatitis E virus in the Middle East and North Africa region: a systematic review.

INTRODUCTION: Hepatitis E virus is a leading cause of hepatitis in the Middle East and North Africa region. Although several countries in this area were shown to be endemic for hepatitis E, little is known about the epidemiology and possible preventive measures. In this manuscript, we present the results of a systematic review addressing the seroprevalence of hepatitis E antibodies in the Middle East and North Africa region. Subsequently, we discuss the main prevention strategies for this virus. METHODOLOGY: We performed a literature review using the PubMed Database of all the Studies reporting data on hepatitis E seroprevalence (Anti-hepatitis E IgM and IgG) among the 20 countries of the Middle East and North Africa region from January 2000 to July 2021. RESULTS: Eighty-nine articles were identified and included in our review. Ten of the MENA countries did not have any study that fits our criteria. Egypt and Iran were the countries with the highest IgG seroprevalence for hepatitis E reaching 85.1% and 68.6% respectively. Concerning acute hepatitis E presentations, Iraq and Egypt were shown to have the highest IgM seroprevalence reaching 38.1% and 35.3% respectively. Hemodialysis and poly-transfused patients as well as patients with concomitant hepatotropic viruses' infections were reported to have a higher seroprevalence than the general population. CONCLUSIONS: Hepatitis E is a major healthcare problem in the endemic Middle East and North Africa region. Even though no definite prevention strategy was described until today, implementing multiple minor precautionary approaches could help reduce the virus spread.

What provokes a disappearing arachnoid cyst? - Case study and literature review.

OBJECTIVE: Intracranial Arachnoid cysts (AC) are stable cerebral spinal fluid (CSF)-filled sacs that can rarely undergo progressive shrinkage or disappearance throughout life. In this manuscript, we present a case of post-traumatic complete resolution of an AC, review the possible triggers of this phenomenon, and discuss the pathophysiological mechanisms behind them. METHODS: After presenting our case, we performed a literature review using the PubMed Database of all the reported cases of AC reduction or resolution (last updated in February 2021). Spontaneous cases were excluded. An analysis of the remaining cases (1985-2021) according to their inciting event, demographical, and clinical characteristics was then presented. RESULTS: 58 patients were identified, 33 of which spontaneously resolved. The remaining 25 were included in the survey in addition to the case we presented. The mean age was 20.2 years, average time to resolution was 25.3 months, with only two third of the cases showing complete disappearance of the AC. A central nervous system infection was the inciting cause of resolution in one infant (4%), a history of head trauma in 16 (62%) patients and an intracranial procedure in 9 (35%) patients. DISCUSSION: AC disappearance is a rare phenomenon that can occur spontaneously or after an inciting event. The cyst wall rupture and CSF flow perturbation theories seem to be the most applicable pathophysiological mechanisms in triggered AC resolution.

PARP inhibitors: a tsunami of indications in different malignancies.

The evolution of precision medicine in the field of oncology has led to a radical change in the course of malignancies. PARP inhibitors are drugs that block the activity of the PARP enzyme responsible for base excision repair and have shown significant positive response when used for tumors lacking homologous recombination, namely high efficacy among BRCA-mutated tumors. Since 2014, when olaparib received an accelerated US FDA approval in ovarian cancer, we witnessed many other FDA approvals for olaparib, rucaparib, niraparib and talazoparib. Additionally, many Phase I, II and III trials were published presenting revolutionizing results. Other ongoing trials combined PARP inhibitors with checkpoint inhibitors. We aimed in this review to state the FDA approvals for PARP inhibitors in breast, ovarian, fallopian tube and primary peritoneal cancers, report the major published trials in high impact medical journals, and mention the ongoing trials combining these drugs with checkpoint inhibitors.