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MAKE YOUR STUDIES COUNT Pearls for Effective Lab/Imaging Consults James L. Fanelli, OD, FAAO Introduction Why Order Imaging Test Co-Management vs. Direct Involvement Clinical Confirmation refer vs. orchestrate confirmatory diagnosis Adjunct to Thorough Examination covering the bases What is the Right Radiology Test? Plain Film X-Ray Computed Tomography (CT) Magnetic Resonance Imaging (MRI) Magnetic Resonance Angiography (MRA) Other? Clinical Indications for CT over MRI Assessment of Bony Abnormalities Detection of Lesion Calcification i.e.. Retinoblastoma; Chronic Sinusitis Detection of Bony Destruction i.e.. Fractures i.e.. Metastatic Disease Assessment of Sinuses i.e.. Blowout Orbital Emphysema Clinical Indications for CT over MRI Assessment of Hyperacute Hemorrhage Orbital or Intracranial Orbital Lesions unless Surface Coil Technology is used Where MRI is Contraindicated MRI Contraindications Ferromagnetic Ocular or Orbital Foreign Body Pacemakers Metallic Cardiac Valves Non-MRI Compatible Intracranial Aneurysm Clips Patient Limitations time of testing and postural demands size of the patient Common Errors in Neuro-Imaging The Wrong Scan for the Problem The Wrong Area Imaged The Wrong Technique Requested (or the correct technique not requested) Poor Communication between Clinician and Radiologist Lack of recognition of Clinical Situations not Requiring Imaging When NOT to Order Imaging Typical Migraine Headache Patient with Typical Microvascular Cranial Mononeuropathy (i.e.. VI N Palsy with Diabetes) Patient with Clear Evidence of MG Hysterical or Malingering Patients Include Contrast Material in MRI??? Always Include Gadolinium Contrast with MRI of Brain and Orbits EXCEPT: Trauma where CT is better choice Known vascular malformations Stroke (Infarction or Hemorrhage) Previous Hypersensitivity to Gad or other Contrast Media Has MRA Replaced Conventional Angiography? MRA is Safe and Non-Invasive can screen for arterial stenosis, venous occlusions, AV malformations, and aneurysms MRA Fails to Demonstrate 20% of Cerebral Aneurysms Conventional Angiography remains the “Gold Standard” for: Exclusion of Aneurysms Surgical Planning Accurate Diagnosis Are All MRI Scanners Equal? Quality Determined By: strength of magnetic field size of the magnet gradient coil strength and technology surface coil technology software Are All MRI Scanners Equal? Open MRI Scanners are Not as Good as Conventional Scanners low field strength therefore lower spatial resolution image capture time increased therefore more susceptible to motion do not allow orbital coils Still Better than CT for Soft Tissue Analysis What About Fat Suppression? Structures that are Hyper-Intense (blood, contrast material) can be hidden when juxtaposed to orbital fat Used in conjunction with gadolinium Mandatory on any MRI study of the optic nerves Clinical Case: SUSPECTED PATHOLOGY Optic Neuritis PREFERRED SCAN MRI Brain and Orbits Pearls... MRI of Brain and Orbits with and w/o Gadolinium, with fat suppression. 2 mm sections DX: Left Optic Neuritis R/O: Optic Nerve Mass or Compression R/O: Demyelination Clinical Case: SUSPECTED PATHOLOGY Orbital Tumor PREFERRED SCAN MRI/CT Orbits Pearls... MRI of Orbits, with gadolinium, with fat suppression, 2 mm sections R/O Tumor/Mass CT in lieu of MRI if mass is believed to be of bony origin Clinical Case: SUSPECTED PATHOLOGY Orbital Trauma PREFERRED SCAN CT Orbits Pearls... CT Orbits, axial and coronal views, without contrast DX: left orbital trauma RO: orbital floor (or medial wall) Fx. Clinical Case: SUSPECTED PATHOLOGY Pituitary Tumor PREFERRRED SCAN MRI Brain Pearls... MRI of Brain, with attention to sella, with and w/o gadolinium DX: bitemporal visual field defects RO: Pituitary abnormality Clinical Case SUSPECTED PATHOLOGY III N. Palsy PREFERRED SCANS MRI & MRA Brain Pearls... MRI/MRA Brain with gadolinium DX: Left Third Nerve Palsy RO: aneurysm at junction of Posterior Communicating A. and Internal Carotid A. Clinical Case: SUSPECTED PATHOLOGY Homonymous Hemianopsia (asymptomatic) PREFERRED SCAN MRI Brain Pearls... MRI of Brain with and w/o gadolinium DX: Left Homonymous Hemianopia RO: Lesion in Right Post-Chiasmal Visual Pathways Clinical Case: SUSPECTED PATHOLOGY Homonymous Hemianopsia (acute and in distress) PREFERRED SCAN CT Brain Pearls... CT Brain with and w/o enhancement DX: Left Homonymous Hemianopia RO: Right Post-Chiasmal Visual Pathway Lesion, Acute Infarction Suspected Clinical Case: SUSPECTED PATHOLOGY IV or VI N. Palsy (non-traumatic) PREFERRED SCAN MRI Brain Pearls... MRI of Brain with and w/o gadolinium, with emphasis on midbrain and Ventricular System DX: Isolated IV or VI Palsy RO: Posterior Fossa Mass or Mass Effect Clinical Case: SUSPECTED PATHOLOGY Bilateral Optic Atrophy (Progressive Pallor) PREFERRED SCAN CT Brain Pearls... CT Brain with and w/o contrast, 5 mm axial and coronal sections DX: Progressive Optic Atrophy RO: Organic Brain Syndrome (don’t forget the heavy metal screening) Clinical Case: Suspected Pathologies: Multiple Diagnostic Lab Studies Required Anemia Hyperlipidemia Wegener’s Collagen Vascular Pearls Pearls for each lab study discussed Concluding Pearls Communicate Clinical History Communicate Suspected Pathology Ask for Attention to Specific Anatomical Areas Specify Preferred Views (eg. 2mm coronal views) Specify Preferred Technique (eg. Fat suppression) Concluding Pearls Don’t Be Afraid to Ask Don’t Be Afraid to Tell Questions?
