David Joyner

Cross-modal deactivations during modality-specific selective attention

BackgroundProcessing stimuli in one sensory modality is known to result in suppression of other sensory-specific cortices. Additionally, behavioral experiments suggest that the primary consequence of paying attention to a specific sensory modality is poorer task performance in the unattended sensory modality. This study was designed to determine how focusing attention on the auditory or visual modality impacts neural activity in cortical regions responsible for processing stimuli in the unattended modality.MethodsFunctional MRI data were collected in 15 participants who completed a cued detection paradigm. This task allowed us to assess the effects of modality-specific attention both during the presence and the absence of targets in the attended modality.ResultsThe results of this experiment demonstrate that attention to a single sensory modality can result in decreased activity in cortical regions that process information from an unattended sensory modality (cross-modal deactivations). The effects of attention are likely additive with stimulus-driven effects with the largest deactivations being observed during modality-specific selective attention, in the presence of a stimulus in that modality.ConclusionModality-specific selective attention results in behavioral decrements in unattended sensory modalities. The imaging results presented here provide a neural signature (cross-modal deactivation) for modality-specific selective attention.

Balamuthia Mandrillaris Meningoencephalitis associated with Solid Organ Transplantation - Review of Cases

We report the first identified transmission of Balamuthia mandrillaris through solid organ transplantation. Kidneys were transplanted from a donor with presumptive diagnosis of autoimmune encephalitis. Shortly after, the recipients developed neurologic symptoms. Magnetic Resonance Imaging of the brain from the donor and both kidney recipients demonstrated multiple ring enhancing lesions with surrounding edema and adjacent leptomeningeal extension. In addition most of the lesions demonstrated signal changes suggesting central hemorrhagic foci. Specimens were tested locally and at the Centers for Disease Control and Prevention. Histopathology revealed B. mandrillaris in either brain tissue and/or cerebral spinal fluid in the donor and recipients.

An unusual cause of acute headache: subarachnoid free air secondary to spontaneous bronchopleurodurosubarachnoid fistula from a Pancoast tumor

Pneumocephalus and pneumorrhachis are related to transgression of the barriers to the central nervous system. We present a patient with a Pancoast tumor treated with palliative chemoradiation who developed symptomatic spinal and intracranial air caused by spontaneous bronchopleurodurosubarachnoid fistula secondary to direct tumor invasion into the thecal sac.

Liposarcoma of the glottis: A report of an unusual diagnosis in an unusual location

Liposarcoma of the larynx is a rare entity, typically well differentiated with a good prognosis. We present a patient who presented to ENT clinic with a 3-month history of hoarseness. Contrast-enhanced computed tomography of the neck demonstrated a 2.5-cm mass of the true vocal cord, which biopsy demonstrated to be dedifferentiated liposarcoma of the larynx. The patient went on to total laryngectomy with planned adjuvant radiation therapy. The presentation and imaging findings of laryngeal liposarcoma are nonspecific, but this neoplasm should be considered in the differential of masses in the head and neck.

Lethal disseminated dysembryoplastic neuroepithelial tumor following West Nile virus: Report of a very unusual combination

Dysembryoplastic neuroepithelial tumors (DNETs) are typically benign World Health Organization (WHO) grade I tumors of the cortical or deep gray matter with a favorable prognosis. We encountered a patient with DNET who has been evaluated and treated for West Nile encephalitis 7 months before presentation. Over the course of 2 years, the patient developed diffuse leptomeningeal carcinomatosis. As the disease burden increased, the patient eventually became quadriparetic. The patient elected for hospice care and expired shortly thereafter. Autopsy revealed DNET (WHO grade I) with extensive involvement of the cervical, thoracic, and lumbar spinal cord, bilateral cerebellar hemispheres, brainstem, the cortex of the right frontal and temporal lobes, and meningeal carcinomatosis of the brain and spinal cord. Mortality from DNET is rare, and as per our extensive literature search, there has been only 1 case reported of death attributed to seizures from this diagnosis. To the best of our knowledge, this is the only case of disseminated DNET with meningeal infiltration or carcinomatosis resulting in mortality.

Glioblastoma Presenting with Acute Middle Cerebral Artery Territory Infarct

Acute ischemic stroke caused by a malignant mass has been described in the literature in few case reports. We describe an unusual case of acute ischemic middle cerebral artery distribution infarction secondary to glioblastoma.

Opportunistic bone density screening for the abdominal radiologist using colored CT images: a pilot retrospective study

PurposeThe purpose of the study was to develop an accurate and reproducible method for detecting low spinal bone density on abdominal CT images.MethodsFor this IRB-approved HIPAA-compliant single-center retrospective study, nonenhanced CT images of the lower abdomen were obtained in 631 African-American participants. Mean attenuation of L3/L4 was associated with quantitative CT bone density (QCT) in a randomly selected training cohort (N = 511), and receiver operating characteristics analysis was used to identify the optimal mean attenuation threshold for differentiating normal from low bone density. Custom image processing software was used to generate grayscale and colored CT images of the midline spine, with green for normal and red for low bone density. Five radiologists independently assessed bone density at L3/L4 in a validation cohort (N = 120) using various methods: QCT, visual assessment of sagittal grayscale images (Grayscale), quantitative measurement of mean attenuation on a midline sagittal image (Attenuation), and visual assessment of a midline sagittal colored image (Color). Accuracy was calculated using the average QCT bone density as a reference standard. Inter-observer agreement was assessed using intraclass correlation coefficient (ICC).ResultsThe optimal mean attenuation threshold for differentiating normal from low bone density at L3/L4 was 145 Hounsfield Units. The average accuracy of Grayscale, Attenuation, and Color methods was 58, 87, and 91% (p < 0.001), respectively. Inter-observer agreement was poor for Grayscale (ICC: 0.20; 95% CI 0.12, 0.28) and excellent for both Attenuation (ICC: 0.85; 95% CI 0.73, 0.91) and Color methods (ICC: 0.87; 95% CI 0.83, 0.90).ConclusionDetection of low spinal bone density using colored abdominal CT images was highly accurate and reproducible.

SU-E-I-69: Magnetic Resonance Metal Artifact Evaluation with Routine Clinical Cardiac Sequences

PURPOSE To examine schemes to grade the severity of metal susceptibility artifacts on image quality using cardiac MRI pulse sequences. METHODS A post-thoracotomy patient was simulated with a stainless steel sternal wire (Syneture,MA; size=6, diameter=48mm), placed securely on an ACR MRI phantom. Phantom was scanned on a 1.5-T Siemens using cardiac MRI sequences:1)TrueFISP, 2)Gradient-Recalled-Echo (GRE), 3)Turbo-Spin- Echo (TSE), 4)Turbo-Inversion-Recovery-Magnitude (TIRM), 5)Dark- blood-IR-FS (DBFS) with and without the wire (FOV=30×30cm, slice- thickness/slice-gap=7.0/1.5mm, matrix size=192×192, slices=17). Image quality degradation was assessed in terms of signal loss and spatial deformation; signal loss by a) measuring the largest diameter of signal drop and b) number of slices with a signal drop and spatial deformation in VelocityAI (Atlanta,GA) by computing the rigid transformation indices between the phantoms internal grid with and without the metal. RESULTS Image quality was evaluated in terms of signal loss, spatial deformation and ring artifacts. Signal loss: TruFISP and GRE showed the largest signal drop diameter (13 and 16cm respectively). GRE sequence showed a signal drop in -12 slices where as signal drop occurred in only ∼4-5 slices with other sequences. Spatial deformation: GRE sequence showed the maximum with a ∼9mm grid deflection followed by TSE and DBFS (∼8mm). An average deflection of 5.4mm was observed on most of the sequences except T rueFISP and TIRM (Omm). Rigid body transformation showed a maximum x,y,z-translation of -4.7, 0.3 and 1.69 mm and x,y,z-angular rotation of 0.2, - 1.5 and 0.5° for GRE sequence followed by TSE and DBFS confirming the spatial distortion results. Concentric ring artifacts with signal loss were also observed on TrueFISP and DBFS images. CONCLUSIONS Quantification of cardiac MR sequences to metal tolerance and the impact on image quality has shown that GRE and TrueFISP are the most metal-susceptible and TIRM is the most metal-tolerant sequence in terms of both signal loss and spatial deformation. This study helped in creating a separate cardiac metal protocol comprising of mainly metal-tolerant sequences thus reducing scan time and patient discomfort.