Daily IM q/a - happy_studying

[ArchivalUser]

Q. 59 yo f is evaluated for a 1 week h/o increasing pain of right foot.She recalls stepping on a nail about 1 month ago.patient has a 5 year h/o heart failure secondary to dilated cardiomyopathy and has implantable cardioverter-defibrillator,her meds are lisinopril,furosemide,spironolactone,carvedilol. On p/e vitals are normal,exam of foot reveals tenderness and warmth directly below proximal 5th metatarsal bone.radiograph of R foot is normal.which of the following is most appropriate next step to establish diagnosis?
A.MRI
B.CT scan
C.Gallium scan
D.Three phase bone scan

[ArchivalUser]

BB

I KNOW MRI is CI for sure with ICD and gallium is CI with Renal disease
not much info for other

[ArchivalUser]

change my answer to DD

[ArchivalUser]

me too
am confused between B & D!!

[ArchivalUser]

B but only because of ICD, otherwise MRI for sure.

[ArchivalUser]

What if there was an option for biopsy
Wouldn't that be the most accurate ???

How's three phase bone scan different from
Gallium scan

[ArchivalUser]

CT..

[ArchivalUser]

Ans: CT scan
For clinical suspicion of osteomyelitis ,MRI is indicated but here the patient is in defibrillator and hence MRI C/I.
When to order which test is always a puzzle in osteomyelitis
But as far as i have known
1.Radiographs always!!
2.MRI-acute and active cases, MRI show changes within days of infection and can detect soft tissue abscesses so it remains the mainstay for diagnosing acute/active cases unless contraindicated..
The patient in the vignette is in ICD and hence C/I,so dont do MRI in this case
3.CT-scan is the choice where MRI cannot be done.
Also,CT is best in chronic cases to visualize calcified ---involucrum,sequestrum etc

About nuclear study
Bone scan has same sensitivity as MRI but MRI is more specific than bone scan
Hence,use bone scan when MRI specificity is decreased s/a
Infected hardware
Neuropathic feet

About gallium scan ,it may still be used to visualize inflammation and chronic infections but leukocyte labeled nuclear scan have replaced this imaging technique!!

Key point in this vignette ::
CT scan is the imaging study of choice for suspected osteomyelitis when MRI cannot be done!!

Please correct me if i am wrong or if somebody else has better explanations !!

Thank you all for the discussion

[ArchivalUser]

@arjun
Bone biopsy is the most accurate but when u have noninvasive procedure like MRI with higher specificity for diagnosis and thereby reducing exposure to invasive procedures i think we will we go with the imaging modality as the diagnostic tool . Also, the question above asks about next appropriate step ,not most accurate!
I have not encountered any questions regarding biopsy so far,
Will let u know if i come across such clinical scenarios .