Transcript Ordering a study - NP/CNM/PA Professional Practice Group

Ordering Radiological
Exams
Alex Rybkin MD
Assistant Clinical Professor of Radiology
SFGH/UCSF
Nancy Omahen RN MSN NP
Referral Coordinator, Radiology SFGH
How to order?
What to order?
(Assumed: imaging is clinically indicated)
Motivation
• “I never give accurate history to
Radiologists: it biases them and makes
me trust them less.”
“Blinded” Radiologist
False Negative Rate
37%
For PCP Pneumonia!
Radiology Studies
Prevalence
(Pre-test
prob)
PPV, NPV
(Post-test
prob)
Sensitivity: x
Specificity: y
PCP Pneumonia
Hx: Hypoxia in an
AIDS patient with
CD4 = 57
Result: PCP Pna
Hx: SOB
Result: ???
Sens & Spec vary!
(And it’s a good thing)
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Clinical situation
Experience
Ability/Training
Adaptation to
technique
– Techs
– Hardware
– Display methods
Why Radiologist is not a tool, but a
CONSULTANT
• Results not binary
• Multiple signs and
findings
• How to combine
prevalence info with
complex results
• Most important:
Radiologist has a brain
Don’t Blind Your Radiologist
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Think Radiologist as a consultant
Invest time and effort
Help us help you
Summarize signs/symptoms/history
– Tell us what you want to know
– ICD9 (so we can bill)
Do we need clinical info?
• 2 schools of thought:
– Radiologists: We need it, but we are not
going to get it
– Non-radiologists: They don’t REALLY need
it
REALITY: Not getting enough specific
information
Status Quo
• Chest study: “CP”, “SOB”
• Abdominal study: “Abdom Pain”
• Brain study: “HA”, “Weakness”
Useless
Example of CT e-referral sent by PCP
(sent the same information for abd/pelvis
CT request)
• Diagnostic Question: R/O malignancy
• History: Constitutional Symptoms
Useless
Status Quo
• Scrotal
Ultrasound:
“R/o Hernia”
Misleading
Why “Rule Outs” are EVIL
• Take us down the wrong path
“R/o Uterine Fibroids vs
Enlarged Prostate”
Crohn’s disease with “creeping fat” producing a subtle mass
Why “Rule Outs” are EVIL
• Take us down the wrong path
• Make us second-guess you
R/o Appendicitis
Why “Rule Outs” are EVIL
• Take us down the wrong path
• Make us second-guess you
• Make Radiologists waffle (cannot
prove a negative)
• Really bad NPV
– Limitations of technique (search)
– “The hardest thing to find is the one
that’s not there”
Why “Rule Outs” are EVIL
They will be rejected by billing &
WE DO NOT GET PAID!!
Diagnosis with:
• R/O diagnosis
• MVA
• GSW
Broken lines of
communication
• Lack of understanding by Providers of
what Radiologists need
• Roadblocks to info access
– Hybrid written/digital ordering
– Lack of unified repository of information
– Lack of continuity of care
Need collaboration within the system!
“But how do I
choose the right
study?”
Heuristic vs Perscriptive
Approach
• “Heuristics are rules of thumb, educated
guesses, intuitive judgements, or simply
common sense” -- Wikipedia
• “Heuristics stand for strategies using
readily accessible, though loosely
applicable, information to control
problem solving” – Perl, J et al
Heuristic #1
• If you don’t know how to proceed, don’t
guess, ask a Radiologist.
• You can also call the Radiology Nurse
Practitioner- x4407
On the Menu:
• Plain Films
• Fluoroscopy
• Ultrasound
• CT (Computerized Tomography)
• MRI (Magnetic Resonance Imaging)
• Nuclear Medicine/PET CT
• Angiography
ACR Appropriateness Criteria
• acsearch.acr.org
Choosing a study
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Comparative studies
Consensus
Usefulness
Do no harm
Availability
Expense
– patient
– system
Heuristic #2
• Use step-wise approach
– Start with inexpensive, less risky studies
– Escalate to more advanced studies as
needed
– No shotgun please!
Imaging Costs (facility fee)
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CXR 1 view
Ultrasound abdominal
CT abdomen with contrast
MRI brain with and w/o gad
$199
$627
$2279
$7875
Plain Films
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Economical
Readily available
Quick
Informative
Good place to start
Chest X-Ray
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First-line study of the chest
Varieties: AP, PA & lateral, decubs
PA & lateral: best quality
AP: standby for immobile patients,
portable studies
• Decubs: eval pleural effusion
Heuristic #3
• Radiological investigation of a Chest
problem should always start with a CXR
KUB & Abd series
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KUB: supine abdominal film
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Abd series: KUB, upright chest, +/decubs
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Evaluation for obstruction
Abnormal calcifications (kidney stones)
Obstruction
Calcifications
Pneumoperitoneum
Further eval: CT
Heuristic #4
• Unless looking for obstruction, don’t
bother with KUB
Extremity Films
• Good for broken bones, lesions
• Very limited Soft Tissue info: effusions,
sq emphysema, foreign bodies
• For better definition of bone: CT
• For better definition of soft tiss: MRI
• For foreign bodies: CT or US
Heuristic #5
• Plain films are more valuable than MRI
for bone problems!
(Known limitations: osteomyelitis, stress
fractures, etc)
General CT considerations
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Quick
Available
Relatively Affordable
Problems:
– Radiation (children, pregnancy)
– Patient Size limit 450 lb
– Patient Motion
– Pt with ESRD
Radiation Exposure
• Up to 2% of cancer estimated due to
CT.
– Brenner et al, NEJM 2007
Heuristic #6
• As Low As Reasonably Attainable
(ALARA)
– US or MRI in children and pregnant women
CT IV Contrast
• Benefits:
– Better contrast in soft
tissues
– Better delineation of tissue
types
– Better sensitivity for
tumors/abscesses
• Risks
– Kidney damage (eGFR <
60)
– Allergic reactions
– Fluid overload
IV Contrast (cont)
• Need eGFR/Cr within 30 days
• eGFR < 15 NO CONTRAST
• eGFR bet 15 and 60
– Consent
– Hydration
– Bicarb (Visipaque, N-AC(mucomyst) not
effective)
Allergic Reactions
• Hx of life-threatening reactions is an
absolute contraindication for contrast
• Important to know if pt has had prior reaction to
intravenous contrast- screen pt for allergies!
• True allergy- anaphylactic (Type I reactions) or mild
(delayed Type 4).
• For mild reactions: premedicate
– Call CT for protocol x8069
Head CT
• Trauma
• Neurosurgical/Neurological
Emergencies
• For detailed exam: MRI
• Contrast:
– to better characterize
abnormalities seen on
noncon
– Suspected tumor, abscess
etc
– HIV
Spine CT
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Trauma
Acute Abnormalities
Chronic Abnormalities: MRI
Spine compression: MRI
CT myelogram when MRI not possible
Chest CT
• Routine Chest CT: noncon, 2.5 mm cuts, no
skips
– Good for masses, nodules, effusions
– Give contrast for better imaging of mediastinum, pleura
• High Res CT (HRCT): noncon, 1mm cuts, 1-2
cm skips
– Interstitial lung disease, airways disease
– Expiratory images, prone images
• PE Protocol CT: with contrast, 1.25 mm cuts,
no skips, bases and apices excluded
– PE, vascular abnormalities
Abdominal CT
• Routine Abd/Pelvis
– Most abdominal indications
– Oral, +/- Rectal and IV
contrast
• Renal Stone protocol
– noncon, thin cuts
• Specialized organ
protocols:
– talk to you friendly
Radiologist
Heuristic #7
• For most abdominal problems requiring
imaging, CT is most bang for the buck
Liver studies
• Liver Protocol CT: 3
phases
– Arterial, Portal, Delayed
• Alternative-- US:
– less radiation, less
sensitivity
– useless in proven cirrhosis
• Alternative MRI:
– better specificity, less
availability
Abdom CT: Enteric Contrast
• Not absorbed
– Minimal risks
• Neutral vs Positive contrast
– Neutral (hypertonic): better bowel wall
definition
– Positive: better for perforation, abscess
MSK CT
• Exquisite definition of fractures
• Usually for preop planning
• For most problems rely on plain films
and MRI (bone vs soft tissue problems)
Ultrasound
• Fast, Cheap, NO RADIATION
• Limitations:
– Operator dependent
– US does not go through bone, air
– Labor intensive
– Small field of view
• Typical indications: RUQ pain, Ob/Gyn
imaging, Thyroid, Vascular imaging
Heuristic #8
• US not good for fishing expeditions
– Use US for specific indications
• If you are going fishing, go with CT
General MRI
• Uses High Strength Magnetic fields
– No ionizing radiation
– Pacemaker absolute contraindication
– Metal in body relative contraindication
• Better for Soft Tissue imaging
• Slow, scheduling difficult, expensive
MRI Contrast
• Gadolinium compounds
• Used for better ST
characterization
• Allergic reactions rare
• Nephrogenic Systemic
Fibrosis (NSF):
– Rare, recently discovered
– Chronic Renal Failure
– Requires consent 15 < eGFR
< 30
NSF- nephrogenic systemic
fibrosis
• Nephrogenic systemic fibrosis is a rare
disease of unknown cause that affects
patients with renal failure. Single cases
led to the suspicion of a causative role
of gadolinium that is used for magnetic
resonance imaging.
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1. Marckmann P, Skov L, Rossen K et al (2006) Nephrogenic systemic fibrosis: suspected
etiological role of gadodiamide used for contrast-enhanced magnetic resonance imaging. J
Am Soc Nephrol 17:2359–2362 [PubMed]
2. Grobner T (2006) Gadolinium—a specific trigger for the development of nephrogenic
fibrosing dermopathy and nephrogenic systemic fibrosis? Nephrol Dial Transplant 21:1104–
1108 [PubMed]
3. Flaten H (GE Healthcare) (2006) Dear Healthcare Professional.
http://www.fda.gov/medwatch/safety/2006/gadolinium_NFD-NSF_dhcp.pdf. Accessed 07
Sept 2006.
Neuro MRI
• Brain: usually second-line
study (following abnl CT)
• Spine: best for cord,
paraspinal pathology,
degenerative processes
• Needs contrast for tumors,
infections
MRA vs CTA
MRA
– Non invasive eval of arterial system
– Images flow, not anatomy-slow flow may mimic
stenosis/occlusion
– Typical applications: intracranial, neck, renal/mesenteric,
peripheral
CTA
Heuristic #9
• There are true MRI emergencies
– Cord compressions
– Posterior fossa infarcts
– Appendicitis in pregnant pt
Abdominal MRI
• Always second-line study
(Except: proven cirrhosis)
• Liver: high specificity for
HCC
• MRCP: Noninvasive
Bile/pancreatic duct
imaging
• Pelvis: GYN pathology
characterization, staging of
GYN tumors.
MSK MRI
• Soft tissue pathology:
tendons, ligaments,
menisci, capsules,
muscles etc.
• Osteomyelitis
• MSK Tumor staging (plain
films for characterization)
Heuristic #10
• MRI is not part of DJD management
– Start with plain films
Osteomyelitis
• Plain Film: sens 43-75% spec 75-83%
(1)
• Triple phase bone scan: sens 94% spec
95%(1)
• MRI ROC meta-analysis: superior to
bone scan (2)
(1) Semin Roentgenol. 2007 Apr;42(2):92-101.
(2) Arch Intern Med. 2007 Jan 22;167(2):125-32.
Conclusion
• Don’t Blind your Radiologist
• “Rule Outs” are EVIL
• Participate! Don’t be discouraged.
Choosing Studies
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Don’t guess, ask Radiologist
Use step-wise approach
For chest problems, start with CXR
KUB is for obstruction
For bone problems start with plain films
ALARA
In abdomen CT is most useful
Ultrasound is not for fishing
There are rare MRI emergencies
MRI is not for DJD
Contact numbers
Urgent (within 14 days) MRI requests:
– NP x4407 Rads (neuro)x5798 Abd Imaging Rads x5898,
Musculoskeletal Rads x8030
Urgent (within 14 days) CT requests:
-NP x4407 CT chief Tech Kevin x8069 (if unable to reach
either of the above, you can contact the numbers above for
Rads.
For Scheduling problems:
MRI-x 5949
CT, PET CT, US, Nuclear Medicine- Mary Cobbins, Supervisor x5498
THANK YOU!