Imaging of Skull Base Tumors.

The skull base provides a platform for supporting the brain while serving as a conduit for major neurovascular structures. In addition to malignant lesions originating in the skull base, there are many benign entities and developmental variants that may simulate disease. Therefore, a basic understanding of the relevant embryology is essential. Lesions centered in the skull base can extend to the adjacent intracranial and extracranial compartments; conversely, the skull base can be secondarily involved by primary extracranial and intracranial disease. CT and MRI are the mainstay imaging methods and are complementary in the evaluation of skull base lesions. Advances in cross-sectional imaging have been crucial in the management of patients with skull base pathology, as this represents a complex anatomical area that is hidden from direct clinical exam. Furthermore, the clinician must rely on imaging studies for therapy planning and to monitor treatment response. It is crucial to have a thorough understanding of skull base anatomy and its various pathologies, as well as to recognize the appearance of treatment-related changes. In this review, we aim to describe skull base tumors and tumor-like lesions in an anatomical compartmental approach and present imaging methods that aid in diagnosis, management, and follow-up.

Editorial Comment: Estimation of venous sinus pressure drop in patients with idiopathic intracranial hypertension using 4D-flow MRI.

KEY POINTS: • Work-energy equation using 4D-flow MRI is a promising technique for non-invasive estimation of trans-stenotic pressure drop in patients with idiopathic intracranial hypertension.• Additional research with larger and multicentric prospective cohorts is needed to validate the results, along with improvement of the segmentation process with automated techniques and shortening of scanning times to allow for practical clinical use.

Demonstration of technical feasibility and viability of whole eye transplantation in a rodent model.

INTRODUCTION: Whole eye transplantation (WET) holds promise for vision restoration in devastating/disabling visual loss (congenital or traumatic) not amenable to surgical or neuroprosthetic treatment options. The eye includes multiple tissues with distinct embryonic lineage and differential antigenicity. Anatomically and immunologically, the eye is unique due to its avascular (cornea) and highly vascular (retina) components. Our goal was to establish technical feasibility, demonstrate graft viability, and evaluate histologic changes in ocular tissues/adnexae in a novel experimental model of WET that included globe, adnexal, optic nerve (ON), and periorbital soft tissues. METHODS: Outbred Sprague-Dawley rats (n = 5) received heterotopic vascularized WET from donors. Each WET included the entire globe, adnexa, ON, and periorbital soft tissues supplied by the common carotid artery and external jugular vein. Viability and perfusion were confirmed by clinical examination, angiography and magnetic resonance imaging (MRI). Globe, adnexal, and periorbital tissues were analyzed for histopathologic changes, and the ON was examined for neuro-regeneration at study endpoint (30 days) or Banff Grade 3 rejection in the periorbital skin (whichever was earlier). RESULTS: Gross examination confirmed transplant viability and corneal transparency. Average operative duration was 64.0 ±â€¯5.8 min. Average ischemia time was 26.0 ±â€¯4.2 min. MRI revealed loss of globe volume by 36.0 ±â€¯2.8% after transplantation. Histopathology of globe and adnexal tissues showed unique and differential patterns of inflammatory cell infiltration. The ON revealed a neurodegeneration pattern. CONCLUSION: The present study is the first in the literature to establish an experimental model of WET. This model holds significant potential in investigating mechanistic pathways, monitoring strategies or developing management approaches involving ocular viability, immune rejection, and ON regeneration after WET.

The value of qualitative and quantitative assessment of lesion to cerebral cortex signal ratio on double inversion recovery sequence in the differentiation of demyelinating plaques from non-specific T2 hyperintensities.

OBJECTIVES: To assess the usefulness of the visual assessment and to determine diagnostic value of the lesion-to-cerebral cortex signal ratio (LCSR) measurement in the differentiation of demyelinating plaques and non-specific T2 hyperintensities on double inversion recovery (DIR) sequence. MATERIAL AND METHODS: DIR and fluid-attenuated inversion recovery (FLAIR) sequences of 25 clinically diagnosed multiple sclerosis (MS) patients and 25 non-MS patients with non-specific T2-hyperintense lesions were evaluated visually and LCSRs were measured by two observers independently. RESULTS: On DIR sequence, the calculated mean LCSR ± SD for demyelinating plaques and non-specific T2-hyperintense lesions were 1.60 ± 0.26 and 0.75 ± 0.19 for observer1, and 1.61 ± 0.27 and 0.74 ± 0.19 for observer2. LCSRs of demyelinating plaques were significantly higher than other non-specific T2-hyperintense lesions on DIR sequence. By using the visual assessment demyelinating plaques were differentiated from non-specific T2-hyperintensities with 92.8 % sensitivity, 97.5 % specificity and 95.1 % accuracy for observer1 and 92.8 % sensitivity, 95 % specificity and 93.9 % accuracy for observer2. CONCLUSION: Visual assessment and LCSR measurement on DIR sequence seems to be useful for differentiating demyelinating MS plaques from supratentorial non-specific T2 hyperintensities. This feature can be used for diagnosis of MS particularly in patients with only supratentorial T2-hyperintense lesions who are categorized as radiologically possible MS. KEY POINTS: • Demyelinating plaques and non-specific T2-hyperintensities have different SI on DIR images. • These differences can be assessed by LCSR measurement or visual assessment. • There is an excellent inter-observer agreement for both methods. • This feature can be used in radiologically possible MS cases.

An Extremely Rare Intersection: Neurolymphomatosis in a Patient with Burkitt Lymphoma Detected by 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography.

Neurolymphomatosis (NL) is a rarely seen neurologic involvement of the systematic lymphoma. Its diagnosis is challenging, and requires biopsy. In cases where biopsy is not appropriate, 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) may aid in diagnosis. Here, we present a 54-year old male patient diagnosed with Burkitt lymphoma who underwent FDG-PET/CT in order to evaluate the treatment response after chemotherapy and radiotherapy. On viewing PET/CT images of the patient who complained of pain and weakness in his upper extremities after therapy, linear FDG uptake was observed in bilateral cervical 5 (C5), left cervical 6 (C6), bilateral cervical 7 (C7), and right lumbar 4 (L4) nerve roots. Magnetic resonance imaging (MRI) revealed dilation and thickening of nerve roots consisted with FDG uptake observed on PET/CT images. Since biopsy was not performed, histopathological diagnosis could not be established. However, overlapping of clinical, PET/CT, and MRI findings strongly suggested the presence of NL. As is the case of this patient, in cases with non-Hodgkin lymphoma, a combined evaluation of FDG-PET/CT and MRI modalities aid in the establishment of the diagnosis of NL.

Brain herniations into the dural venous sinus or calvarium: MRI findings, possible causes and clinical significance.

OBJECTIVES: To determine frequency, imaging features and clinical significance of herniations of brain parenchyma into dural venous sinuses (DVS) and/or calvarium found on MRI. METHODS: A total of 6160 brain MRI examinations containing at least one high-resolution T1- or T2-weighted sequence were retrospectively evaluated to determine the presence of incidental brain herniations into the DVS or calvarium. MRI sequences available for review were evaluated according to their capability to demonstrate these herniations. Patients' symptoms and clinical findings were recorded. RESULTS: Twenty-one (0.32 %) brain parenchyma herniations into the DVS (n = 18) or calvarium (n = 3) in 20 patients were detected. The most common locations of the herniations were the transverse sinuses (n = 13) and those involving inferior gyrus of the temporal lobe (n = 9). High-resolution T1- and T2-weighted sequences were equally useful in the detection of these brain herniations. According to clinical symptoms, brain herniations were considered to be incidental but headaches were present in nine patients. CONCLUSION: Brain herniations with surrounding cerebrospinal fluid (CSF) into the DVS and/or calvarium are incidental findings and not proven to be associated with any symptoms. Although rare, these herniations are more common than previously recognized and should not be confused with arachnoid granulations, clots or tumours. KEY POINTS: • Brain herniations into the DVS are more common than previously assumed. • The most frequent locations are the transverse sinus. • These herniations are incidental findings. • The relationship between brain herniation into DVS and headache is uncertain. • High-resolution MR sequences are most useful in detection of brain herniations.

Malformations of cortical development: 3T magnetic resonance imaging features.

Malformation of cortical development (MCD) is a term representing an inhomogeneous group of central nervous system abnormalities, referring particularly to embriyological aspect as a consequence of any of the three developmental stages, i.e., cell proliferation, cell migration and cortical organization. These include cotical dysgenesis, microcephaly, polymicrogyria, schizencephaly, lissencephaly, hemimegalencephaly, heterotopia and focal cortical dysplasia. Since magnetic resonance imaging is the modality of choice that best identifies the structural anomalies of the brain cortex, we aimed to provide a mini review of MCD by using 3T magnetic resonance scanner images.

Split-bolus MR urography: synchronous visualization of obstructing vessels and collecting system in children.

Several vascular abnormalities related with urinary system such as crossing accessory renal vessels, retroiliac ureters, retrocaval ureters, posterior nutcracker syndrome, and ovarian vein syndrome may be responsible for urinary collecting system obstruction. Split-bolus magnetic resonance urography (MRU) using contrast material as two separate bolus injections provides superior demonstration of the collecting system and obstructing vascular anomalies simultaneously and enables accurate preoperative radiologic diagnosis. In this pictorial review we aimed to outline the split-bolus MRU technique in children, list the coexisting congenital collecting system and vascular abnormalities, and exhibit the split-bolus MRU appearances of concurrent urinary collecting system and vascular abnormalities.

A case of tension pneumothorax during hyperbaric oxygen therapy in an earthquake survivor with crush injury complicated by ARDS (adult respiratory distress syndrome).

Pneumothorax (PTX) is rarely reported in patients receiving hyperbaric oxygen (HBO2) therapy. Patients with air-trapping lesions in the lungs and those with a history of spontaneous PTX, lung disease, mechanical ventilation or chest trauma are at an increased risk for PTX during HBO2 therapy. A 28-year-old male earthquake survivor was referred to our center for multiple wounds 21 days after being rescued from the debris. He had been intubated and put on mechanical ventilation for three days because of adult respiratory distress syndrome (ARDS). At initial presentation, he was conscious, well-oriented and hemodynamically stable. The initial six HBO2 treatments were uneventful. On the seventh HBO2 treatment, the patient lost consciousness and developed cardiopulmonary arrest near the end of decompression. The HBO2 specialist accompanying the patient inside the chamber immediately initiated CPR. A diagnosis of tension PTX was made. After the patient was removed from the chamber, a chest tube was inserted, which improved the symptoms. Although rare, tension PTX can occur during HBO2 therapy. Early diagnosis and intervention are crucial for saving a patient's life. Increased vigilance is required during treatment of patients with risk factors for PTX.

MRI diagnosis of dural sinus - Cortical venous thrombosis: Immediate post-contrast 3D GRE T1-weighted imaging versus unenhanced MR venography and conventional MR sequences.

OBJECTIVE: Primary aim is to compare the diagnostic value of contrast-enhanced 3D GRE T1-weighted sequences with unenhanced MR venography and conventional magnetic resonance imaging (MRI), in detection of dural venous sinus (DVS) and cortical venous thrombosis; secondary aim is to determine the relationship between DVS thrombosis/site and gender, age, infarction or hemorrhage. METHODS: We retrospectively reviewed conventional MR images, unenhanced MR venography and immediate post-contrast 3D GRE T1-weighted MR images in 30 patients (17 male and 13 female, 21-70 years old, mean age 40.1) with clinically suspected DVS thrombosis. MR examinations had been performed with 1.5T or 3T MR Scanners. DVSs were evaluated in 10 sub-segments, including cortical veins. Each set of MR images were examined separately, blinded to the final diagnosis. Associated findings were also noted and sensitivity, specificity and accuracy of each MRI technique were calculated. RESULTS: Final diagnosis of cortical venous and/or dural sinus thrombosis was established in 24 (80%) of 30 cases and 67 (22.3%) out of 300 segments. For detection of the thrombotic segment, sensitivity, specificity, and accuracy were 83.6%, 95.3%, and 92.7% by conventional MR sequences, 89.6%, 91.8%, and 91.3% by unenhanced MR venography, and 92.5%, 100%, and 98.3% by contrast-enhanced 3D GRE T1-weighted sequence, respectively. Infarction and hemorrhage were more frequent in cases with cortical venous thrombosis, while gender and age had no significant relation with DVS thrombosis or its site. Conventional MR sequences and unenhanced MR venography were helpful due to additional information they provided in some cases with isolated cortical venous thrombosis, with hyperintense thrombus material and with associated hemorrhage or infarction. CONCLUSION: Contrast-enhanced 3D GRE T1-weighted MRI is the most accurate imaging method for the detection of DVS and/or cortical venous thrombosis. Infarction and hemorrhage were more frequent in cases with cortical venous thrombosis.

Complete currarino syndrome recognized in adulthood.

Currarino syndrome is a hereditary pathology that is characterized by sacrococcygeal bone defect, presacral mass, and anorectal malformation. Sacrococcygeal bone defect is almost always a part of the syndrome. The complete form of this entity displays all three abnormalities and is very uncommon. In this report, we present the magnetic resonance imaging findings of a case with complete form of Currarino syndrome recognized in adulthood.

Hepatocellular carcinoma review: current treatment, and evidence-based medicine.

We read with great interest the recent article entitled "Hepatocellular carcinoma review: Current treatment, and evidence-based medicine" by Raza et al, published in World Journal of Gastroenterology. Authors evaluated treatments for early and advanced stage hepatocellular carcinoma based on an extensive review of the relevant literature. They reported that radiofrequency ablation is the most effective local ablative therapy. They concluded that RF ablation is equivalent to surgical resection in well selected patients with early stage hepatocellular carcinoma. In addition, we want to mention microwave ablation besides RF ablation.