Download PET Scanning for Solid Malignancies

PET Scanning for Solid Malignancies:
What to Image, What Not
Andrew Quon, M.D.
MIPS
Molecular Imaging
Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Different Tumors have different affinities
for glucose
SUV is an approximation of Glucose Metabolism
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Hot, Medium Hot, Not so Hot
SUV
15
10
Melanoma
Hodgkin’s/NHL
Colorectal CA
Non-Small Cell
Lung Cancer
Esophageal CA
Head/Neck CA
5
Hot
Infiltrating ductal CA
Poorly diff - thyroid
Testicular CA
Pancreas
Bronchoalveolar CA
Cervical CA
Renal cell CA
Medium Hot
Lobular Breast CA
Prostate CA
Primary ovarian CA
Well diff - thyroid
Not So Hot
Most Common Tumors Evaluated by FDG PET/CT
1.
2.
3.
4.
5.
6.
Lung cancer
Melanoma
Esophageal cancer
Colorectal cancer
Head and neck cancer
Lymphoma
Cervical cancer
Breast cancer
Thyroid cancer
GIST
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Lung Cancer
• Diagnosis/Detection: Histologic type
Pitfalls
• Staging:
Primary Tumor (T-staging)
Mediastinal Lymph Nodes (N-staging)
Extrathoracic metastases (M-staging)
• Restaging/Treatment Monitoring:
Evaluation of therapy response
Detection recurrence & metastases
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Primary Detection of Lung Cancer
Histology and pitfalls
1. Be wary of patients with prior history of granulomatous disease or
active infection
2. Bronchioloalveolar Carcinoma and typical Carcinoid tumors have a
higher false negative rate than other lung carcinomas
Sensitivity >93%, specificity 80%
MIPS
Molecular Imaging
Program at Stanford
Stanford University
School of Medicine
Department of Radiology
PET for T-Staging Lung Cancer
n = 40
All cases were histopathologically correlated
MIPS
Imaging Method
Correct T-Staging (%)
CT alone
58%
PET alone
40%
Visual Correlation of
PET and CT
65%
Fusion PET-CT
88%
Lardinois 2003 N Engl J Med
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
PET for Mediastinal Staging in NSCLCa
Meta-analysis of 39 studies
MIPS
Gould 2003 Ann Intern Med
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Extrathoracic Metastases
• PET detects an unexpected distant metastasis in
10-20% of lung cancer cases
• PET is more accurate than CT for evaluating
adrenal and liver metastases
• Because of greater specificity, PET may be more
accurate than bone scanning for metastases
(~95% vs 85%)
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Melanoma
• Detection: FDG avidity in Histologic types
Size limitations
• Staging: Comparison to SLN staging
Staging in clinically advanced cases
• Restaging/Treatment Monitoring:
Detection recurrence & metastases
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Melanoma Primary Detection
• Melanoma is amongst the most FDG avid malignancies
- Also avid in Ocular and Mucosal Melanoma subtypes
- Scarce data on Desmoplastic and Clear Cell Melanoma
• A 2000 study on size and lesion detectability in melanoma:
Size of Metastases (mm)
% Metastases Found by PET (n=114)
(23)
(83)
(100)
(100)
(100)
(100)
≤5
6-10
11-15
16-20
21-25
> 25
• PET has limited role in primary melanoma detection/screening
MIPS
Crippa J Nucl Med 2000
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
• 144 prospectively recruited patients with early stage melanoma
• A direct comparison between using FDG PET initial staging versus SLN
biopsy with complete histologic correlation
• FDG PET sensitivity for local metastatic lymph nodes was 21% (PPV 67%)
MIPS
Wagner 2005 Cancer
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
PET for Initial Melanoma Staging
• PET has a limited role in staging patients with early disease
(i.e. patients negative for suspected adenopathy: Stage I and II)
• Sentinel lymph node (SLN) dissection is superior to PET for
detecting locoregional lymph node spread (particularly
micrometastases)
• PET is limited in detecting brain metastases and
micrometastases
• PET is used primarily for evaluating suspected distant
metastases where it is superior to conventional imaging (patients
with stage III and IV disease)
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Surveillance and Restaging Melanoma
•
High risk (Stage III and IV) patients should be
evaluated periodically by PET imaging after treatment
•
Patients with established recurrence should have a
restaging exam to evaluate additional metastatic
disease
•
FDG PET is the single best diagnostic exam for this
clinical scenario
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Esophageal Cancer
Histologic type
• Diagnosis/Detection Comparison to EUS
Primary Tumor (vs. EUS)?
• Staging Local Lymph Nodes
Distant metastases
• Restaging/Treatment Monitoring
Evaluation of neoadjuvant therapy
Detection recurrence & metastases
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Esophageal Cancer Primary Detection
• Histology: Squamous cell carcinoma and adenocarcinoma perform equally well
on FDG PET and moderate to high avidity
• Be wary of false negative PET in adenocarcinoma with high mucin content
• Current practice: The initial diagnosis of esophageal cancer remains the realm
of endoscopy, endoscopic ultrasound and CT; PET may be used adjunctively
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
PET for Esophageal CA Initial Staging
• For PET has no role in T-staging the primary tumor
(Endoscopic Ultrasound)
• The primary staging role of PET is to evaluate distant
metastases and as an adjunct to EUS for locoregional lymph
nodes
• PET appears better than CT overall for detecting distant
disease
• Mixed results regarding FDG PET and evaluation of liver
metastases
MIPS
Hustinx 2004 Rad Clin NA
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
FDG PET for Evaluation of Neoadjuvant Chemo
•
The goal of neoadjuvant treatment is to diminish primary tumor volume
and extent of disease prior to surgical resection
•
PET is useful for evaluating chemotherapy response and selecting
eligible candidates for subsequent surgery
•
Growing data that PET provides strong predictive data: PET responders
may expect significantly longer overall survival vs. non-responders
Weber J Clin Oncol 2004
Colorectal Cancer
• Diagnosis/Detection: Histology
Screening
• Staging:
Primary Tumor (T-staging)?
Lymph Nodes (N-staging)
Distant metastases (M-staging)
• Restaging/Treatment Monitoring:
Evaluation of therapy: Hepatic vs. Extrahepatic
Detection of recurrence & metastases
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Colorectal Cancer Primary Detection
• FDG PET is very avid for colorectal adenocarcinoma;
- May be only 50% sensitive for mucinous subtype
- Little data on squamous and signet ring subtypes
• Some studies report PET is capable of detecting both
pre-malignant and malignant lesions incidentally
• However, the cost is still prohibitive and effectiveness
is unclear in a screening population
• Current practice: Periodic colonoscopy and
evaluation through occult blood tests are still standard
for primary detection
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
PET for Initial Staging Colorectal Cancer
• Limited role in initial staging
• Most patients undergo surgery for staging of the primary tumor
• Not effective for T-staging colorectal cancer
• Poor sensitivity for evaluating locoregional nodal spread
• PET has good accuracy in evaluating liver metastases but liver
ultrasound commonly performed preoperatively
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Primary Role of FDG PET in Colorectal CA:
Restaging and Surveillance
•
Restaging: PET is more accurate than ultrasound for evaluating the liver and
superior to CT for detecting abdominal metastases
•
PET particularly effective for detecting extrahepatic disease prior to resection
of recurrent liver metastases
•
Surveillance: Pooled data shows PET has a sensitivity of greater than 90%
and specificity of ~75% in detecting recurrence
•
PET particularly emphasized in patients at high risk for recurrence (by initial
staging) and/or rising CEA levels
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Head and Neck Cancer
Tumor types/histology
• Diagnosis/Detection: Use for unknown primary H/N
Primary Tumor (T-staging) vs. MRI?
• Staging Mediastinal Lymph Nodes (N-staging)
Distant metastases (M-staging)
• Restaging/Treatment Monitoring
Evaluation of therapy response
Detection recurrence & metastases
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Tumor types/Histology
•
Most work has been done on squamous cell carcinoma (SCC)
•
Other pathologies
–
–
–
–
–
Thyroid carcinoma
Lymphoma
Mucosal melanoma
Salivary gland tumors
Sinonasal undifferentiated CA (SNUC)?
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Clinical Utility of PET:
Unknown Primary Head and Neck Cancer
• Some patients present with nodal SCC and the 1o site is unknown
• Diagnostic work-up:
- Cross-sectional imaging (MR)
- Panendoscopy with “blind” bx of several sites + tonsillectomy
• Empiric XRT to likely sites with neck dissection of no primary site is found
• PET may be used adjunctively to identify primary site, best done prior to
panendoscopy
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Sample Case: Unknown Primary
• Multiple necrotic nodes on CT, FNA showed squamous cell carcinoma
• No 1o site seen; no MR due to pacemaker
• Endoscopy with biopsies 3 wks earlier was reported as negative,
tonsillectomy had not been done
MIPS
Case courtesy of Nancy Fischbein, MD
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
FDG PET Nodal Staging: Studies
Author
Adams
Benchaou
Braams
Kau
Laubenbacher
McGuirt
Myers
Pai
Paulus
Stoeckli
Stokkel
Stokkel
Stuckensen
Year
1998
1996
1995
1999
1995
1995
1998
1999
1998
2002
1999
2000
2000
Sens
90%
72%
91%
87%
90%
83%
78%
82%
50%
25%
100%
96%
70%
Spec
94%
99%
88%
94%
96%
82%
100%
100%
100%
88%
90%
90%
82%
No. pts
60*
48
12
70
22
45
14
7
25
12
20
54
106
Comment
N0-N2c
N0-N2
N0-N3
Neck sides evaluated
N0-N3
N0-N2
N0
Mostly NPC
Micromets in 5 FN
All N0 patients
Neck sides
Dual head PET
Prospective
Sensitivity: ~90%; Specificity 82-100%
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
PET for Staging for Head/Neck Cancer
• PET does not have enough anatomical detail for adequate T-staging
of H/N cancer
• PET is useful for detecting additional nodal and distant metastases
• The sensitivity of PET for lymph node staging is remarkably variable:
- Poor sensitivity in patients with clinically staged N0 disease
- Excellent sensitivity in patients with established nodal disease
- Good specificity overall
• PET also valuable for detecting second primary lesions (e.g. lung)
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Strength of PET in Head/Neck Cancer:
Post Treatment Evaluation of Residual/Recurrent Disease
•
Clinical and imaging follow-up are limited: tissue edema, fibrosis,
distortion
•
FDG-PET sensitivity 80-100%, specificity 43-100%
•
High negative predictive value: disease is unlikely to be present
if test is negative (very few false negatives)
•
Mixed evidence that PET may have considerably less accuracy
(~70%) after XRT, particularly within 12 weeks (although some
authors report 6 weeks)
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
Sample Case: PET post-treatment
•
Patient s/p XRT and chemotherapy for base
of tongue cancer
•
Questionable residual disease on MRI
•
FNA biopsy confirmed all focal sites on PET
Summary of Clinical Role of PET:
Key Points for Each Tumor Type
1. Lung Cancer
• Primary role: Initial staging (particularly N and M staging), evaluation of
therapy, early prediction of prognosis, restaging/surveillance
• Be wary of: Bronchioloalveolar CA (BAC) false negatives, granulomatous
false positives
2. Melanoma
• Primary role: Initial staging of patients with stage III & IV disease,
restaging/surveillance
• Weakness: Poorly evaluates locoregional lymph node spread, i.e.
sentinel lymph node (SLN) dissection is better
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology
1.
2.
3.
4.
i Summary of Clinical Role of PET (con’t):
i
Key Points for Each Tumor Type
i
Esophageal
• Primary role: Initial staging of distant disease (M staging), evaluation of
neoadjuvant chemotherapy response, restaging/surveillance, early
prediction of prognosis
• Note: Endoscopic ultrasound (EUS) likely better for initial staging of
locoregional lymph nodes and the primary lesion
5. Colorectal
• Primary role: Detection of recurrence (particularly in patients with rising
CEA), restaging recurrent disease,
• Note: PET mainly adjunctive role for initial T and N staging
6. Head and Neck
• Primary role: Initial staging of patients with suspected nodal disease by
physical exam & MRI, evaluation of therapy, restaging/surveillance
• Be wary of: PET utility questionable for initial staging of patients with
negative nodal disease (N0) by exam & MRI, poor T-staging, accuracy
diminished after XRT
MIPS
Molecular Imaging Program at Stanford
Stanford University
School of Medicine
Department of Radiology