How to Order and Interpret Radiology Studies

How to Order and Interpret Radiology Studies 

Thomas Howard, MD 

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Musculoskeletal Imaging in Sports Medicine 

Thomas Howard, MD, FACSM 

Garry W. K. Ho, MD 

Objectives 

1. Review the 

musculoskeletal 

imaging modalities 

available 

2. Discuss radiographic 

evaluation of specific 

musculoskeletal 

injuries 

Plain Film X-Ray X 

Radiography 

Ionizing-radiation x-ray x 

emitter 

Detector 

– Photographic plate 

– Photostimulable phosphor 

– Others 

Radio-opacity opacity / radio-lucency 

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Radiography 

Advantages 

– Inexpensive 

– Readily available 

– Excellent spatial resolution 

– “Real-time” availability as 

fluoroscopy 

Limitations 

– Two-dimensional 

Need > two orthogonal views 

– Relatively poor soft tissue 

contrast resolution 

Useful for radio-opaque 

opaque 

foreign bodies 

Useful if emphysema 

or free air present 

– Ionizing radiation exposure 


Radiography 

– Contraindications 

Pregnancy 

– More of concern for 

L-spine & pelvis XR 

– Minimal radiation 

exposure to fetus 

with shielding when 

imaging other areas 

Computed Tomography 

CT uses an array of x-raysx 

X-ray beams directed at several 

different angles 

Processed by computer to 

produce cross sectional images 

Findings are described as 

radio-opaque opaque or radio-lucent 

329


Images reconstructed - 2D or 3D 

Kinematic CT - imaging of joint motion 


Advantages 

– High contrast resolution of images 

– Excellent images of bones and lungs 

IV contrast infrequently needed for 

orthopedic trauma 

– Wide availability 

– Faster than MRI 


Limitations 

– Can produce artifacts (motion, metal) 

– Less soft-tissue tissue contrast than MRI 

– Exposure to ionizing 

radiation 

Radiation dose much higher 

than for conventional 

radiography 

– Higher cost than 

conventional x-rayx 

330


Contraindications 

– Pregnant women should not have CT 

scans 

Except in life-threatening 

emergencies 

Can be scanned with 

shielding depending 

on body part (minimal 

radiation exposure to 

fetus if ankle or knee 

is scanned) 

– Scanner weight-limits for obese patients 

Bone Scan (Scintigraphy( 

Scintigraphy) 

Biologically active 

drugs are labeled 

with radioisotopes 

Radioisotope 

administered 

Giving off gamma 

rays 

Detected by 

gamma camera 

Processed by 

computer 


Scintigraphy) 

Forms a functional image 

of soft tissues and bone 

Two main types: 

– Planar (“traditional( 

bone scan”) 

Three phase bone scan 

– SPECT – cross- 

sectional and 

reconstructed bone 

scans 

331


Scintigraphy) 

Triple phase bone scan: 

– Flow (perfusion) study 

60 seconds after injection 

Blood flow 

– Blood Pool 

Increased circulation, blood 

vessel dilation 

– Delayed 

2 -33 hrs after injection 

Bone uptake 

– Clearance from extraosseous 

tissues 

Scintigraphy - SPECT Imaging 

(Single Photon Emission Computed Tomography) 

Three-dimensional imaging technique used in 

conjunction with radioisotope injection 

Enhanced tissue contrast 

Improved sensitivity and specificity of lesion 

detection & localization 


Scintigraphy) 

Advantages 

– Images metabolic activity 

of osteoblasts 

Very sensitive for acute 

fractures & tumors 

Old, less metabolically 

active fractures & tumors 

may not show up 

– Less radiation exposure 

than chest x-ray x 

& CT 

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Scintigraphy) 

Limitations 

– Lacks significant detail 

– Poor spatial resolution 

– Poor specificity 

– Displays activity of osteoblasts 

Old fractures (eg( 

eg. . pars defects) may not show up 

Certain tumors with little osteoblastic activity (eg( 

eg. 

multiple myeloma and lytic mets) ) not reliably seen 


– Exposes patient to ionizing radiation 

– Children & pregnant women should be carefully 

shielded 

Magnetic Resonance 

Imaging (MRI) 

Majority of clinical MRI utilizes the magnetic 

moment of hydrogen nuclei (protons) 

Magnetic Resonance Imaging 

Magnetic field protons excited alignment 

Protons snap back into original alignment 

detectable rotating magnetic field 

Protons in different tissues realign at different 

speeds detected as differing signal intensities 

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MRI studies – many different type of studies, 

sequences, and protocols 

Basically two types: 

– T1 

Ideal for studying anatomy 

Fat is white 

– T2 

More valuable in studying 

pathology 

Water is white (H2O) 

Contrast studies 

– Highlight certain structures 

& abnormalities 


Advantages 

– Excellent contrast 

resolution 

Especially for 

soft tissue pathology 

– High sensitivity in 

bone marrow 

diseases 

– Electromagnetic radiation instead of 

ionizing radiation 


Limitations 

– Most sensitive to artifact from motion & metal 

– Claustrophobia 

– Some findings are subtle 

Dependent upon 

interpretation 

Eg. labral tears 

– High cost; lower availability 

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– Pacemakers 

(under investigation) 

Pracically, , an absolute 

contraindication 

– Prosthetic cardiac valves 

safe after 6 weeks 

– Stents & grafts 

Non-ferromagnetic are safe 

Ferromagnetic are safe after 6 weeks 

– Due to epithelialization 

Abdominal aortic aneurysm stents check with 

radiologist 

– Pumps – check with radiologist 

– Other devices may malfunction or be contraindicated 


Contraindications (continued) 

– Metal objects 

Can migrate, heat up, torque 

Foreign bodies, body piercings, jewelry 

Situational clearance 

– Fragment in brain or 

eye contraindicated 

– Bullet in femur or 

muscle likely OK 

– Tattoos & cosmetics can 

heat up 

Metallic dyes 


Contraindications (continued) 

– Obese patients 

Scanner table weight limits 

Gantry opening might be 

too small 

– Pregnancy 

Animal studies conflicting 

Avoid during 1 st trimester 

No gadolinium unless 

absolutely necessary 

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Ultrasonography 

Uses high-frequency sound 

waves to produce images 

Can define masses, fluid, & 

localize foreign bodies 

Findings are described as 

hyperechoic, hypoechoic, , or 

anisotropy 

Allows for dynamic 

evaluation 

Newer systems are more 

compact with higher 

resolution 

Ultrasonography - Tendons 

Bright structure with longitudinally oriented bundles 

Ultrasonography - Tendons 

Blurring, thickening, loss of normal architecture 

336

Ultrasonography - Muscles 

Gastrocnemius 

with hematoma 

Complete disruption 

of fibers on dynamic 

evaluation of rectus 

femoris 

Low Back Pain 

Who do you image 

Ask yourself: 

– Do you have a 

pathoanatomic 

diagnosis 

– Do you need to rule out 

tumor, infection, or 

fracture 

– Will imaging change 

your treatment 

“Red Flags” for imaging: 

– major trauma 

– age > 50 

– unrelenting pain at 

rest or night pain 

– fever, chills, sweats 

– unexplained weight loss 

– history of cancer 

Low Back Pain 

– incontinence of bowel or bladder 

– progressive weakness 

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Low Back Pain 

Conventional x-rayx 

(plain films) 

– AP 

– Lateral 

– Lumbosacral (LS) spot view 

L5 centered view 

Minimizes potential for over-read 

read 

of disk space narrowing 

– Disk space narrowing, 

osteophytes, , fracture, tumor, 

or spondylolisthesis 

Low Back Pain 

Conventional x-rayx 

– Oblique views 

Best if concern for 

pars interarticularis 

fracture 

(spondylolysis) 

– Pars interarticularis 

narrow portion of 

bone between 

superior & inferior 

articular facets 

Low Back Pain 

Bone Scan / Scintigraphy 

– Suspected spondylolysis not seen on plain 

film x-raysx 

– Determine old versus new spondylolysis 

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Low Back Pain 

Lumbar Spine MRI 

– Excellent for 

Disc disease & herniation 

Cord compression 

– Also will demonstrate: 

Spinal cord anomalies 

Tumors 

Discitis 

Vertebral osteomyelitis 

Low Back Pain 

CT Scan 

– Excellent bone study for vertebral fracture 

Usually done in conjunction with MRI 

– Useful for spondylolysis 

Chronic non-union / fibrous union 

Chronic Low Back Pain 

Consider guided injections 

– Fluoroscopic SI, facet injections, 

epidural steroids 

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Cervical Spine Injuries 

Initial C-spine C 

trauma series 

– Cross-table lateral 

– Anteroposterior (AP) 

– Open-mouth 

odontoid 


Lateral view 

All vertebrae on the 

lateral 

Presence of lordosis 

Vertebral alignment 

– Anterior vertebral line 

– Posterior vertebral line 

– Spinolaminal line 

– Posterior spinous line 

Soft tissue examination 


Anterior soft tissue 

– “66 at 2 and 2 at 6” 6 rule 

< 6 mm at C2 

< 2 cm (20 mm) at C6 

– C1-C3 C3 < 5-7mm5 

– C4-C7 C7 = 14-22 mm 

– Increased soft tissue 

space suggests occult 

fracture 

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AP view 

– Spinous processes 

should line up 

midline 

– Vertebral bodies & 

articular pillars also 

line up 

– Vertebral body 

height 


Odontoid view 

– C1-2 2 articulation 

– Alignment 

Gaps between C1 

lateral masses & 

C2 dens (odontoid( 

odontoid) 

Lateral margins of 

C2 articulating 

facet & C1 lateral 

masses 

– Fractures 

Dens 

Jefferson fracture – ring of C1 broken 

from axial loading 


Dynamic flexion-extension 

extension 

– Active voluntary test 

– Undetected 

ligament 

disruption or 

instability 

– Requires alert, 

cooperative 

patient 

stopping for 

pain or 

paresthesias 

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Widening of the predental space from rupture of 

the transverse ligament 


CT scan 

– Suspect bony injury 

despite normal plain 

films 

– Suspect instability on 

plain films 

– Better visualize 

fracture, evaluate for 

displacement 

MRI 

– Evaluate spinal canal, 

nerve roots, and/or 

soft tissue injury 

Shoulder Injury 

“Standard” series 

– AP in external rotation 

& internal rotation 

– Axillary lateral view 

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Scapular Y view 

– AKA: supraspinatus outlet view, 

scapular lateral view 

– Dislocation & angulation of 

proximal humerus fractures 

– Acromial morphology 

– Good lateral view when patient 

cannot tolerate an axillary view 


MRI and MRI arthrography 

– Nonsurgical diagnostic test of choice for 

internal derangements and structural 

instability assessment 

– Soft tissue and bone lesions well demonstrated 


Ultrasound 

– Non-invasive 

– Allows for dynamic 

evaluation 

– Both operator & 

equipment 

dependent 

343

Standard views 

– PA view: 

2 mm intercarpal 

joint space 

3 arcs 

– Lateral view: 

4 Cs 

Wrist Injury 

Wrist Injury 

Complex joints may 

require additional views 

Scaphoid fracture: 

– Scaphoid views 

– If initially negative 

Immobilize x 2 - 3 weeks 

Repeat plain films 

– If still negative and 

symptomatic MRI 

Chronic Wrist Pain 

Hamate Fracture 

– CT scan 

Keinbock’s Disease 

– X-ray, bone scan, MRI 

Carpal Instability 

– X-ray angles, 

MR arthrogram 

TFCC Injury 

– MR arthrogram 

Occult Ganglion 

– MR arthrogram 

Complex Regional Pain 

Syndrome, Type I 

– Bone scan 

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Plain film X-raysX 

Hip Pain/Injury 

– Good initial study 

– Arthritis 

– Late avascular necrosis 

– Initial evaluation for 

femoral neck stress 

fracture 

– Can miss grade 4 

cartilage damage 


MRI 

– At least 1.5 T magnet 

– Surface coil 

– Poor for for IA cartilaginous injuries 

– Good for evaluation of femoral neck 

stress fractures 

MR Arthrogram 

– Labral pathology 

Increased sensitivity, but also 

increased false positive 

– Gad sequences can obscure bone 

– Diagnostic anesthetic injection 

Bone Scan 

– Good study for stress fractures 

Ultrasound 


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X-rays 

AP 

view 

Knee Injuries 

Lateral 

view 

Sunrise / 

Merchant view 

Tunnel / 

Notch view 

Advanced imaging 

Knee Injuries 

– CT scan – more detailed evaluation of bony injuries 

– MRI -- imaging modality of choice for soft tissue 

Exertional Leg Pain 

Shin splints (MTSS) vs. stress fracture 

Shin Splints 

– Clinical diagnosis 

– Plain films: look for stress fracture 

– Triple Phase Bone Scan 

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• Stress fractures 


• Initial radiograph: 

normal in up to 70% 

• Fluffy, ill-defined 

sclerotic line 

perpendicular to major 

trabecular lines 

• Periosteal reaction 

Stress Fractures 

• Thin incomplete lucent line 

• May proceed to completion 

• Beware of the “DBL” 

• Bone scan helpful 

Imaging of Early Stress Fractures 

• MRI and bone scan near 100% sensitivity 

• MRI improved specificity 

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Exertional Compartment 

Syndrome 

– Routine MRI & bone 

scan not helpful 

– Compartment pressure 

testing 

Popliteal Artery 

Entrapment 

– MRA 

– Angiography 

Acute Ankle Trauma 

When do you x-ray x 

– Ottawa Ankle Rules: 

Stiell IG, McKnight RD, Greenberg GH, McDowell I, Nair RC, Wells GA, et al. Implementation of the 

Ottawa ankle rules. JAMA 1994;271:827-32. 

Ankle Injuries 

Normal ankle 

(AP view) 

Normal ankle 

(Lateral view) 

Normal ankle 

(Mortise view) 

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Don’t t forget the foot films! 

AP, lateral and oblique 

Contralateral foot films 

Weight-bearing views 

Lateral view 

– Metatarsal shafts & 

tarsal bones align 

AP and obliques 

– 2nd met medial 

border & middle 

cuneiform align 

Chronic Ankle Pain 

MRI 

– Imaging modality of choice for soft-tissue tissue and 

osteochondral lesions 

CT 

– Ankle fractures & bony pathology 

Bone scan 

– Diffuse, non-specific pain 

– F/U CT if needed for further evaluation of stress 

fractures 

Conclusions 

Initial imaging of choice: plain radiography 

– Image before injection 

– Image all trauma 

CT: good for bone 

MRI: good for soft tissue 

– T1: anatomy; T2: pathology 

Scintigraphy: : good for metabolic activity 

Ultrasound: great potential 

– Operator / interpreter & technology dependent 

Imaging selection 

– Based on history and physical 

– Know your specialists’ imaging preferences 

– Consult radiologist as needed 

349

Thank You 

350

How to Order and Interpret Radiology Studies

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