imaging: when to get mri, ct or pet-ct?
TRANSCRIPT
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Imaging:When to get MRI, CT
or PET-CT?
Alina Uzelac, D.O.Assistant Clinical Professor Neuroradiology
UCSF Department of Radiology and Biomedical Imaging
San Francisco General Hospital
Overview
CT
MRI
PET-CT
Advanced Imaging Techniques
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Imaging Studies
Initial Assessment Head and Neck Ca:
degree of local infiltration
regional lymph nodes involvement
presence of distant metastases second primary tumors
Local Infiltration/Tumor Extent
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59 F w/ trauma.
Inseparable medial rectus
muscle
*
Orbital and Intracranial Extension Sinonasal Undifferentiated Carcinoma
Ax CT
Orbital and Intracranial Extension Sinonasal Undifferentiated Carcinoma
Floor of anterior cranial fossa
Medial rectus
Cor CT
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CT or MRI
All Pts. – initial staging MRI or CT for HEAD and NECK SCCa.
particularly useful in Pts. with clinically N0 neck.
CT vs MRI
CT and MRI are complementary to the clinical examination.
…and may also be complementary to each other.
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Bone window
CT = superior for cortical
bone erosion
Bone window
33 M with an inverted papilloma degenerated into SCCa
Local Invasion
Paraglottic fatextension
56 F w/ epiglottic mass
Ax CT w/
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Ax CT w/ Ax T1
Preepiglottic Space ExtensionBase of Tongue SCCa
CT versus MRI ?CT MRI
Sag CT w/ Sag T1
Preepiglottic Space ExtensionSupraglottic SCCa
CT versus MRI ?
*** *
Motion
CT MRI
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Prevertebral ExtensionPyriform Sinus SCCa
Imaging Studies
Initial Assessment Head and Neck Ca:
degree of local infiltration
regional lymph nodes involvement
presence of distant metastases second primary tumors
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Small Abnormal LNs
**
* * *
Ethmoid Sinus SCCaRecurrence
CT versus MRI ?
Preserved fatty hilum
Thickened cortex
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Clinical N0 neck can be PET negative, given small node volume (<1mL).
PET-CT
PET-CT Tongue SCCA
*
Small LN for PET
Ax CT
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**
CT adequate for ossified cartilage
Thyroid Cartilage InvasionLaryngeal SCCa
Ax CT w/ Ax CT w/
Ax T1 Ax T1 w/ Gd
Thyroid Cartilage InvasionLaryngeal SCCa
MRI superior for marrow infiltration
**
*
**
*
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Ax T1 Ax T1 w/ Gd
Thyroid Cartilage InvasionLaryngeal SCCa
MRI superior for marrow infiltration
**
*
**
*
Loss of nl fat bright signal Abnormal enhancement
Ax T2
MRI superior marrow infiltration
**
*
Thyroid Cartilage InvasionLaryngeal SCCaLoss of fat suppression
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MRI Cor T2 MRI Cor T1 w/
MRI > CT for distinguishing malignancy from mucus
33 M w/ sinonasal SCCa s/p resection returns w/ brain abscess
MRI Cor T2 MRI Cor T1 w/
MRI > CT for distinguishing malignancy from mucus
SCCa recurrence
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Returns w/ erythema and swellingax CT w/ cor CT w/
SCCa recurrence
perineuralspread cavernous sinus
SCCa recurrence
Ax CT
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Perineural spread of tumor
(use thinner slice thickness - 3 mm)
Intracranial extension
Nasopharyngeal Ca (initial staging and follow up).
MRI over CT
Intracranial ExtensionNasopharyngeal Ca
bone erosion along vidian canal
ax CT Ax T1 w/
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Dural invasion
Cor T1 Gd
Intracranial Direct ExtensionSNUC
*
MRI Staging of NPC
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PET-CT
? Routine PET for initial staging, unless:
Equivocal findings on CT or MRI.
High risk of distant metastatic disease.
Search for 2nd primary.
Nodal SCCa unknown primary.
To be done before Bx: Guide to area of highest yield
Bx can result in high uptake.
PET-CT
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PET-CT Superior to CT
ax CT
Cor PET-CT
Cricoid Cartilage InvasionSubglottic SCCa
Treatment Response
MRI
PET-CT Done 3 months post treatment completion
(prevent false positives).
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Nonsurgical Treatment Response
- radiologic resolution = cure- reduction in size < 50% = failure- 50–75% reduction = indeterminate
(close surveillance)
Advanced Imaging TechniquesPredicting Tumor Response
PET: High SUV = poor response
Diffusion (DWI) MRI.
Dynamic perfusion MRI (vs CT): Tumor hypoxia = radioresistance (and
chemoresistance).
Increased tumor perfusion => improved locoregional control.
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MRIDiffusion Weighted Sequence for
Tx response prediction
Nodal metastasis
*
Staging MRI tongue SCCa
ax DWI ax ADC
*
MRIDiffusion Weighted Sequence for
Tx response prediction
MRIDiffusion Weighted Sequence for
Tx response
Nodal metastasis
*
Staging MRI Follow up
resolution of abnl diffusion
= Tx response
*
ax DWI ax DWI
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Recurrence Imaging
MRI (extent of tumor)
PET-CT (metastases)
MRIDiffusion Weighted Sequence for
recurrenceax DWI ax ADC
Hx mod diff SCCa tongue p-hemiglossectomy, chemoRT, followed by LND. Recurrence, then radical neck dissection w/ pectoralis
flap.
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52 M w/ Hx NPCA s/p XRT in China 4 years prior
RecurrenceMRI for extent of tumor
Solitary NPC metastasis biopsy-proven.
RecurrencePET for metastases
35 M presents with back pain 2 years after NPC treatment
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64-year-old male status post left totalmaxillectomy and free ALT flap for SCCa, post
chemo and radiation therapy.
*flap
RecurrencePET for flap
Treatment ComplicationsImaging
Complications occasionally incidentally imaged.
MRI
PET-CT
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44yo s/p XRT for NPC.
Post XRT ComplicationsSkull base XRT changes
PET negative
44yo s/p XRT for NPC.
Post XRT ComplicationsSkull base XRT changes
PET negative
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Bitemporal XRT necrosisAx T1 w/ Gd Cor FLAIR
Post XRT Complications
Bitemporal XRT necrosisAx T1 w/ Gd Cor FLAIR Ax PET
Post XRT ComplicationsNo abnormal
hypermetabolism
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Brain necrosis 5 years post XRT for NPC
Post XRT Complications
Ax Gd perfusion
Post XRT Complications
Bitemporal XRT necrosis
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Returns 12/2013 w/ L jaw pain and trismus
Oxaliplatin and CyberKnifeCompleted 07/2013 for recurrent
NPC
XRT necrosis central skull base and nasopharynx
*
Oxaliplatin and CyberKnifeCompleted 07/2013 for recurrent
NPC
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XRT necrosis central skull base and NP
*Masticator mm. acute
denervation
Acute Muscle Denervation P-XRT
PET PitfallAcute Muscle Denervation = High Uptake
Right extraocular mucles acute denervation
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PET PitfallAcute Muscle Denervation = High Uptake
84 M recurrent parotid malignancy
perineural spread
cavernous sinus.Right extraocular mucles
acute denervation
Whole BodyPET-MRI
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Whole BodyPET-MRI
Siemens integrated
PET-MRI
= simultaneous imaging
= superior registration
PET-MRI Siemens integrated
PET-MRI
= simultaneous imaging
= superior registration
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Initial Staging: CT or MRI. MRI for NPC
Consider PET-CT:Distant metastases
Positive neck nodes without identifiable primary
Look for second primary
TAKE HOME POINTSHead and Neck Ca Imaging
TAKE HOME POINTSHead and Neck Ca Imaging Predicting response – ADVANCED
imaging:
MRI Diffusion and Perfusion – tumor oxygenation
PET
MRI-PET!
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TAKE HOME POINTSHead and Neck Ca Imaging
Surveillance: MRI
Recurrence: MRI and PET
Thank you!