Publications by authors named "Fadi El Merhi"

Article Synopsis
  • The study aimed to evaluate how different forms of iodinated contrast media (monomer vs. dimer) affect iodine detection in CT scans using a vascular-specific phantom that mimicked human blood vessel sizes.
  • Researchers tested this by filling cylinders of various sizes with different concentrations of two types of ICM (Iohexol and Iodixanol) and scanned them under varying conditions (tube potential, current, and reconstruction methods).
  • Results indicated that while monomer generally provided better opacification in most cases, the dimer showed superior contrast-to-noise ratios, especially at higher kVp settings, suggesting complex interactions between ICM type and imaging parameters.
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Purpose: The aim of our study is to investigate the impact of iodine quantification on image reconstruction when employing a vascular-specific contrast media phantom with varying iodine concentrations.

Materials And Methods: A 30-cm phantom simulating arterial and venous blood vessel diameters was manufactured. Small (9 mm) and medium (12 mm) cylinders contained iodine concentrations from 10 to 100% while large (21 mm) cylinders were in quartiles from 25 to 100% diluted in blood equivalent medium.

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Background And Study Aims: Bowel wall thickening (BWT) on computed tomography (CT) has been frequently reported by radiologists. There are no clear guidelines regarding the level of thickening that is correlated with definite pathology. Radiologists usually rely on their overall subjective impression, and studies on inter-observer agreement (IOA) are lacking.

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Article Synopsis
  • *A retrospective analysis involved 179 patients, measuring lung density in relation to the lesion and needle path, using statistical tests to analyze variables.
  • *Results indicated that lower lung density and more pleural passes increased the risk of pneumothorax, suggesting these factors could help predict complications during PNLB procedures.
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A 58-year-old male patient, previously healthy, presented with right flank pain of few hours duration. Initial workup showed an elevated creatinine and right hydroureteronephrosis. Computed tomography imaging revealed a retroperitoneal soft tissue mass encasing the right common iliac artery which is a first reported case in its anatomical distribution.

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Aim: To investigate the frequency of different etiologies of acute scrotal pain in males presenting to the emergency department at American University of Beirut Medical Center in Beirut, Lebanon.

Materials And Methods: In all, 94 patients between the ages 18 and 40 years presenting to the emergency room at American University of Beirut Medical Center with acute scrotum were recruited. The scrotum was inspected with palpation, and Doppler Ultrasound of the testicle was performed by a radiology resident to confirm the diagnosis.

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Purpose: This hybrid retrospective and prospective study performed on 200 consecutive patients undergoing renal CTA, investigates the opacification of renal vasculature, radiation dose, and reader confidence.

Materials And Methods: 100 patients were assigned retrospectively to protocol A and the other 100 were allocated prospectively to protocol B. Both protocols implemented a contrast material and saline flow rate of 4.

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Article Synopsis
  • Coronary anomalies affect roughly 1% of the population and can sometimes result in sudden cardiac death.
  • Advanced imaging techniques like coronary computed tomography angiography and magnetic resonance imaging effectively identify these anomalies without invasive procedures.
  • The article aims to provide a detailed classification system for recognizing different types of coronary artery anomalies.
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Human hydatid cyst disease is an international public health issue that particularly affects the developing countries. In this article, we discuss the epidemiology of hydatid disease in third world countries, the life cycle of echinococcus granulosus and how to make the clinical diagnosis of the disease, including laboratory tests and imaging modalities as well as uncommon presentation of this entity that we have encountered at the American University of Beirut Medical Center (AUBMC). We emphasize on the new World Health Organization classification of hepatic echinococcosis with examples from our clinical practice at AUBMC, and finally we describe the treatment, including medical and interventional therapies.

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Objective: To investigate the visualization of mediastinal lymph nodes during thoracic CT employing a multiphasic contrast media (CM) protocol.

Methods: Institutional review board approved retrospective study consisting of 300 patients with known chest malignancy. Patients were allocated to one of two CM protocols: Protocol A, consisted of dual bolus (Phase 1:100 ml CM followed by 100 ml saline chaser) i.

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Crossed unfused ectopia constitutes a very rare variant of ectopic kidneys, with an approximate incidence of 1 : 75000. We hereby describe a rare case of an incidental finding of crossed unfused ectopic kidneys, in a 45-year-old gentleman incidentally found to have a bladder lesion. The unique blood supply of his kidneys has also been described.

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Purpose: The aim of this article was to investigate the opacification of the renal vasculature and the urogenital system during computed tomography urography by using a quadruple-phase contrast media in a triphasic scan protocol.

Materials And Methods: A total of 200 patients with possible urinary tract abnormalities were equally divided between 2 protocols. Protocol A used the conventional single bolus and quadruple-phase scan protocol (pre, arterial, venous, and delayed), retrospectively.

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Objective: To evaluate the performance of non-contrast computed tomography (CT) by reporting the difference in attenuation between normal and inflamed renal parenchyma in patients clinically diagnosed with acute pyelonephritis (APN).

Material And Methods: This is a retrospective study concerned with non-contrast CT evaluation of 74 patients, admitted with a clinical diagnosis of APN and failed to respond to 48h antibiotics treatment. Mean attenuation values in Hounsfield units (HU) were measured in the upper, middle and lower segments of the inflamed and the normal kidney of the same patient.

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Coronary CT angiography (CCTA) has the advantage over invasive coronary angiography in that its non-invasive nature and minimal risk on patients. CCTA enables accurate assessment of the entire heart, coronary artery system and thorax, displaying three-dimensional information about the spatial relations of the anomalous vessels and surrounding intraluminal and extraluminal anatomy, and thereby contributing clinically important prognostic information. Dual left anterior descending (LAD) coronary artery consists of of two LAD arteries within the anterior interventricular sulcus (AIVS).

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Renal pseudoaneurysm (PSA) is a rare complication post kidney transplant biopsy that accounts for less than 1% of allograft dysfunction. Imaging guidelines in the diagnosis of renal PSA have not yet been developed owing to the low occurrence and limited data availability. However, contrast-enhanced CT and magnetic resonance angiography (MRA) are the preferred modalities in detecting PSA owing to the high contrast and spatial resolution.

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Clinical Relevance Statement: Caudocranial scan direction and contrast injection timing based on measured patient vessel dynamics can significantly improve arterial and aneurysmal opacification and reduce both contrast and radiation dose in the assessment of thoracic aortic aneurysms (TAA) using helical thoracic computed tomography angiography (CTA).

Objectives: To investigate opacification of the thoracic aorta and TAA using a caudocranial scan direction and a patient-specific contrast protocol.

Materials And Methods: Thoracic aortic CTA was performed in 160 consecutive patients with suspected TAA using a 256-slice computed tomography scanner and a dual barrel contrast injector.

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This article evaluates the most relevant state-of-the-art magnetic resonance (MR) techniques that are clinically available to investigate multiple sclerosis (MS). The presence of hypo- and hyperintense lesions on T1- and T2-weighted magnetic resonance imaging (MRI) sequences in white matter (WM) is a common finding that is occasionally a diagnostic challenge for the radiologist. The technical requirements and how they may help to understand, classify or follow-up these pathologies are briefly summarized.

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Article Synopsis
  • - A patient with a history of mitral valve issues experienced a new heart problem, diagnosed as an anomalous left coronary artery, which was repaired surgically.
  • - To evaluate the patient's condition before surgery, a specialized imaging technique called coronary computed tomography angiography (CTA) was used, which required careful timing of contrast media for clear visuals of different coronary arteries.
  • - The study concluded that using a test-bolus technique for contrast media significantly enhanced the imaging quality and matched better with the patient’s unique cardiovascular dynamics during CTA.
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Background: Urosepsis is a rare but life-threatening complication following transrectal ultrasound (TRUS) guided needle prostate biopsy. Despite the technological and pharmacological improvements, the problem of bacterial urosepsis after prostate biopsy remains. A strategy for preventing urosepsis following TRUS prostate biopsy in áreas with high prevalence of resistant strains or patients presenting risk factors is lacking.

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Clinical Relevance: Matching contrast injection timing with vessel dynamics significantly improves vessel opacification and reduces contrast dose in the assessment of pulmonary embolism during computed tomography (CT) pulmonary angiography.

Purpose: The aim of this study was to investigate opacification of the pulmonary vasculature (PV) during CT pulmonary angiography using a patient-specific contrast formula (PSCF) and exponentially decelerated contrast media (EDCM) injection rate.

Materials And Methods: Institutional review board approved this retrospective study.

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Over the last decade, exponential advances in computed tomography (CT) technology have resulted in improved spatial and temporal resolution. Faster image acquisition enabled renal CT angiography to become a viable and effective noninvasive alternative in diagnosing renal vascular pathologies. However, with these advances, new challenges in contrast media administration have emerged.

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Article Synopsis
  • The study aimed to compare two CT scan protocols for visualizing head and neck blood vessels during imaging of supraclavicular lymph nodes, focusing on how effectively they enhance vascular opacification.
  • Involving 180 patients, the research tested protocol A (a single-bolus injection) against protocol B (a quadruple-phase dual-injection of contrast and saline), measuring the clarity of arteries and veins.
  • Results showed protocol B significantly improved arterial visibility by 20%, reduced venous visibility by 75%, and provided better overall image quality (higher contrast ratios) while also reducing the effective radiation dose for patients.
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Background: The use of the Coronary Artery Calcium Score (CACS) for risk categorization instead of the Framingham Risk Score (FRS) or European Heart SCORE (EHS) to improve classification of individuals is well documented. However, the impact of reclassifying individuals using CACS on initiating lipid lowering therapy is not well understood. We aimed to determine the percentage of individuals not requiring lipid lowering therapy as per the FRS and EHS models but are found to require it using CACS and vice versa; and to determine the level of agreement between CACS, FRS and EHS based models.

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Multifocal basal ganglia T2-weighted hypointensities are believed to arise mainly from mineralization in and around penetrating arteries and perivascular spaces within gray and white matter structures. Recently, it has been proposed that these hypointensities can serve as a biomarker for small-vessel disease and aging in magnetic resonance imaging when using T2-weighted sequences. With advances in digital coil technology and parameter applications, there has been an increase in image quality and faster examination times.

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