Transcript Diagnostic accuracy of 201Thallium-SPECT and 18F-FDG

Diagnostic accuracy of 201Thallium-SPECT and
18F-FDG-PET
in the clinical assessment of glioma recurrence
Manuel Gómez-Río & Antonio Rodríguez-Fernández &
Carlos Ramos-Font & Escarlata López-Ramírez &
José Manuel Llamas-Elvira
JOURNAL CLUB PRESENTER
KUMAR
This study aimed to test the hypothesis that
incorporation of 18-fluoro-deoxy-glucose
positron emission tomography (FDG-PET)
increases the accuracy of this differential
diagnosis obtained with 201Tl chloridesinglephoton emission computed
tomography (201Tl-SPECT
Seventy-six patients (mean age47.72±16.19
years) under suspicion of glioma
recurrence,42% with low-grade and 58% with
high-grade lesions, were studied by 201TlSPECT and FDG-PET,
Materials and methods
• prospective cohort study at neuro-oncology reference centre
between March 2002 and March 2005 for suspicion of tumour
recurrence.
• Clinical management of patients with glial tumour (WHO
classification is established by the hospital Brain Tumours and
Radio surgery Committee
• Tumour progression is defined according to McDonalds , based
on both clinical (unequivocal relapse of neurological status
after progression-free interval of >3 months) and MRI
(appearance of new enhancing abnormalities or enlargement of
enhanced zone in posttreatmentgliosis area) criteria.
• When examinations yield inconclusive results or suggest
tumour recurrence, the patient is referred to NM Department for
201Tl-SPECTand FDG-PET examinations on the same day
Materials and methods
•
MRI was performed using an 0.5 Tesla General Electric with and
without Gadolinium. Images were analyzed byneuroradiology
specialists, who focused on the appearanceof new enhancing
abnormalities and enlargement of enhanced zone in posttreatment
gliosis area
SPECT
• All patients were examined within 15 min of the i.v. injection of 3–5
mCi 201Tl chloride. Images were acquired using a Triple Head Camera
(Prism 3000; Picker-International) Significantly higher 201Tl uptake
was considered postive.
PET
• All patients fasted for ≥6 h before tracer injection and had a blood
glucose concentration <120 mg/dl at the examination. A standard i.v.
(weight-independent) dose of 185 MBqwas administered using a
Siemens ECAT EXAT 47 PET tomograph.Examinations were
considered positive if unexplainable metabolic activity was observed
demonstrated by increased FDG uptake relative to immediately
adjacent tissue
Assessment of diagnostic accuracy
• The gold standard for tumour recurrence was
based on histological confirmation, recurrence
was considered absent if patient was clinically
stable and showed no MRI changes during >3
months for high-grade and >6 months for lowgrade lesions
• The significance of differences in results among
procedures was analyzed using the Mc Nemar
test for paired samples.
.
Assessment of diagnostic accuracy
Results
• The mean follow-up period for our study cohort was 2.6 years
• The 76 patients studied had a mean age of 47.7 years (SD=16.2)
and 57% were males.
• Histology of the primary lesion is exposed in 32 tumours (42.10%)
were low-grade gliomas, and the remaining 44 were high-grade
gliomas.
• During the study period, three of the low-grade diffuse astrocytomas
(G-II) converted to high-grade forms. The prevalence of tumour
recurrence (72.4%) was similar between low- (62.5%) and highgrade (79.5%) lesions.
• No diagnostic errors were observed in the subgroup of patients with
histological confirmation (23 in our series),with tumour recurrence
confirmed in all cases.
• Table 2 shows the internal and external accuracy parameters and
values estimated for the whole cohort and for each
Results
• subgroup (patients with low or high-grade tumours).Sensitivity
values were similar among the whole cohort and subgroups, with
201Tl-SPECT + MRI always showing higher sensitivity (>95% in
cohort and subgroups) vs FDGPET (70 and 83% in low-grade and
high-grade subgroups,respectively).
• In the high-grade subgroup, specificity was 100% for all procedures,
with no false-positive examinations.
• In the low-grade subgroup, specificity values for 201Tl-SPECT,
201Tl-SPECT + MRI and FDG-PET were 75,83 and 92%,
respectively.
• Accordingly, the likelihood ratio for a positive result was always
higher with FDG-PET
• Conversely, the likelihood ratio for a negative result was lower with
201Tl-SPECT + MRI (0.04)
Discussion
• FDG-PET did not prove to be clearly superior to 201TlSPECT (with or without MRI) for the clinical diagnosis of
glial tumour recurrence,
• The specificity and positive predictive value of FDG-PET
were slightly higher, but its sensitivity and negative
predictive value were appreciably lower.
• Hence, it appears that FDG-PET is slightly better for
confirming tumour recurrence
• 201Tl-SPECT is better for ruling out a possible
recurrence, which was detected in 38% of FDGPET
negative explorations.
Advantages
Limitations
• good quality cohort study
•prospective Cohort study with
reasonable follow-up
• Methodological biases:
Two different gold standard
procedures, especially the follow-up
•reporting results under blinded
conditions using visual analysis.
•There were interpretational error
during radiological analysis
•All images were analysed by
Neuroradiologist
•Reference standards might vary with
imaging tool hence applicability can
be questionable
• Good reference standards had been
used
• Not a multicenter research
•criteria to be established for FDGPET, 201Tl-SPECT, MRI and
combinations of these examinations
WHAT IS ALREADY KNOWN ON THIS TOPIC
Background:
TCS may complement CT and MRI in the postoperative follow-up
of patients with high-grade gliomas. Because none of these
modalities alone is both sensitive and specific, an integrated
analysis of imaging findings is useful. Neurosurgery. 1999
Mar;44(3):469-77; discussion 477-8
(201)Tl-SPECT is a valuable and noninvasive diagnostic procedure
to detect recurrence or progression disease for treated gliomas
and ependymomas. (201)Tl-SPECT has a good correlation with
short term prognosis with excellent diagnostic accuracy.
Clin Transl Oncol. 2006 Oct;8(10):750-4.
The inclusion of diffusion-weighted sequences in postoperative
MR imaging is essential, as is MR imaging immediately before
radiation therapy to monitor disease progression.
J Neurosurg. 2005 Sep;103(3):428-38
WHAT THIS STUDY ADDS
• 201Tl-SPECT should remain as a routine clinical
procedure for the diagnosis of glioma recurrence.
• In high-grade lesions 201Tl-SPECT data had been
useful & MRI did not add
• In Low-grade lesions MRI appears to be useful to
establish the physiologic structures that take up Tl201
• FDG-PET did not prove to be clearly superior to
201Tl-SPECT (with or without MRI) for the clinical
diagnosis of glial tumour recurrence
THANKS