“What Test is Best” Choosing Radiology Exams in Emergency Settings Dr. C. Freeman PGY-4 Dr. A. Olivier

Objectives To provide a guide to selecting the appropriate imaging studies in common emergency settings Please note: the goal of this talk is NOT to review how to read radiological exams.

Modalities Plain Films Ultrasound Based on differential attenuation of X-rays by different tissues Ultrasound Uses sound waves Real time Very accessible No radiation

CT Computer reconstruction of 2 dimensional X-ray data reconstructions in any plane Accessible, fast

WHAT IS A “SPIRAL CT”?????? Helical movement (patient and gantry move at the same time) Almost all modern CT’s are helical Exceptions: Head CT, High Resolution CT of the chest

Soft tissue differentiation (e.g. Soft tissue tumors) MRI Soft tissue differentiation (e.g. Soft tissue tumors) many other specialized indications (e.g. acute stroke) limited accessibility, expensive Expanding role in many clinical situations

CHEST “the patient who is short of breath” Common Causes… CHF, atelectasis, pneumonia, pneumothorax, pulmonary embolus start with a Chest X Ray

Atelectasis Left diaphragm silhouetted Left diaphragm now seen

Complete Collapse

Inspiration-expiration may increase sensitivity Pneumothorax Inspiration-expiration may increase sensitivity

Pneumothorax

Tension pneumothorax ***EMERGENCY place needle in 2nd intercostal space (mid clavicular line)

Pneumonia Air bronchograms Silhouette sign

Pneumonia: Air Bronchogram

Congestive Heart Failure

Pulmonary Emboli CXR V/Q Scan CT Pulmonary Angiogram non specific, non sensitive V/Q Scan useful if high probability or low probability CT Pulmonary Angiogram

CXR: HAMPTON’S HUMP Chest X-ray not useful to rule in or rule out PE BUT may help to find other cause of SOB (e.g. CHF)

V/Q Scan VENTILATION POSTERIOR PERFUSION LATERAL High probability: Treat (anticoagulate) Low probability: unlikely to have PE Intermediate Probability: ??? CT Angiogram

CT ANGIOGRAPHY ACUTE THROMBOEMBOLI

Aortic Dissection CT Trans-esophageal echo

CT Reconstruction: Aortic Dissection

GI/GU Again, begin with a plain film Remember utility of upright and decubitus films for identifying free air and air fluid levels Often move on to another exam depending on plain film findings

Free Air ^^^ ^ Upright Chest X-Ray is the most sensitive test for free air

Free Air: Decubitus View

FREE AIR we see both sides of the bowel wall “Riegler’s sign”

Plain Films CT IVP (ultrasound sometimes useful…e.g. if pregnant) Renal Colic Plain Films CT IVP (ultrasound sometimes useful…e.g. if pregnant)

Ureteric calculus note how well a calcified stone is seen on plain films.

IVP Shows function and obstruction HOWEVER…largely replaced by CT “Left flank pain” IVP Shows function and obstruction HOWEVER…largely replaced by CT

Renal Colic: CT Now Preferred Modality

RLQ Pain, Fever, WBC ……? Appendicitis Plain film of limited utility may see appendicolith Ultrasound No radiation In females, can also see adnexa Especially good in thin patients CT If overweight

..? Appendicitis RLQ PAIN appendicolith

Appendicitis: CT

“distended abdomen with obstipation and peritoneal signs” Bowel Obstruction start with a plain film supine and upright views lateral decubitus if upright not possible

Small Bowel Obstruction Multiple air-fluid levels distended bowel loops note the value of upright (or decubitus) view

Large Bowel Obstruction: Contrast Enema Confirms the site of abrupt narrowing at the splenic flexure (large arrow)

Bowel Obstruction…after the plain film Depends on the clinical scenario May monitor patient May go directly to the Operating Room May proceed to CT helps to define location and cause of obstruction

Pancreatitis Clinical/Biochemical Diagnosis Ultrasound to identify cause (i.e. biliary stones) CT is used to identify and follow complications ***NOT TO DIAGNOSE Will MISS diagnosis in 30% of cases

Scrotal Pain History and Physical first May proceed directly to the OR Ultrasound is the modality of choice Can identify status of blood supply

Testicular Ultrasound

RUQ Pain Ultrasound is the modality of choice CT can miss acute cholecystitis or cholelithiasis

Ultrasound: Cholelithiasis

Neuroradiological Emergencies Start with a CT **Except cord compression May ultimately need an MRI

Clinical Settings Seizures Trauma Headache Stroke

Seizures: CT---Neoplasm

Seizure: MRI---Neoplasm

CT: Stroke Some advanced CT techniques …”CT Perfusion” helpful In the USA, many centers MRI is the initial exam Some specialized MRI Techniques can identify brain at risk (“penumbra”) vs. dead brain

CT Intra - Cranial Bleeds Subarachnoid Hemorrhage Subdural Hemorrhage Epidural Hemorrhage

CT: Subarachnoid Hemorrhage

Epidural Hematoma

Subdural Hematoma

SPINE Emergencies

C-Spine Trauma Plain films: CT MRI If minor trauma, plain films including flexion and extension views can suffice CT For significant injury From skull base to T1 Sagital and coronal reconstructions MRI Unexplained neurologic deficit Unconscious for prolonged period of time

Normal C-Spine with CT Axial Sagital Coronal

Hangman’s # Axial Sagital

C5-6 dislocation Axial Sagital

MR Angiogram C5-6 dislocation with Left Vertebral Artery dissection

Suspected Spine Infection Plain films may be diagnostic Do not demonstrate compression of thecal sac MRI is optimal CT can be adequate Fluoroscopic or CT guided aspiration/biopsy We follow these cases with MRI

Discitis Discitis, Sagital Coronal Axial

Discitis, osteomyelitis prevertebral & epidural phlegmon

Cord Compression: MRI Metastatic Melanoma

Spine Emergencies: Summary MRI is generally the best exam for the spine CT is excellent in many indications Plain films have a limited role MRI access is quite limited, so we compromise and do a lot more CT

MSK

Fractures Remember that acute fractures may not be seen on plain films for up to 7- 10 days. Bone scan is more sensitive

Plain Film: Ankle Fracture

Sacral Fracture: CT

? Septic Joint Plain film may be suggestive MUST aspirate joint This is a medical emergency

Necrotizing Fasciitis Ultimately a clinical diagnosis Plain Films Gas in the soft tissues MRI For surgical planning CT may give a false negative (not sufficient to rule out diagnosis)

Summary Almost always start with the plain film There are some exceptions Neurological Emergencies If you are unsure as to what test is appropriate…talk to the Radiologist

Thank you!! Dr. C. Freeman Dr. A. Olivier