Utility and accuracy of 18F FDG-PET/CT in the detection of cerebral melanoma metastases Sylvia Deryk, Bart Neyns, Mark De Ridder, Frederik Vandenbroucke, Axel Bossuyt, Christian Vanhove, Hendrik Everaert

Objective To investigate the benefit of including the brain in the FOV in FDG-PET/CT scan in MM Sensitivity, specificity and accuracy in the identification of brainM+ 2

Material and methods (1) local database of 18F FDG PET/CT scan: cutaneous MM between 1-4-2008 and 30-11-2009 inclusion of entire brain in FOV CT after IV contrast administration (contrast enhanced-CE) in the venous phase THZ CT PART WAS ACQUIRED AFTER IV CONTRAST ADMINISTRATION IN THE VENOUS PHASE 3

Material and methods (2) Gadolinium-enhanced MRI brain within 3 months time period of PET/CT MRI = golden standard T1,T2,FLAIR sequences Mean ΔT paired PET/CT and MRI= 15.8 days

Material and methods (3) Total of 49 PET/CT and subsequent MRI in 34 patients: 17 Male, 17 Female Age (years) : range 26-80 , mean 52 Clinical stage grouping (AJCC): 24 IV with 12 brain (M1c) - 3 II - 7 I

Results FDG-PET/CT: 73 lesions 3 only on PET + as hypermetabolic 36 only on CE CT + 34 on both PET and CE CT : - 8 hypermetabolic - 26 hypometabolic 3 only seen on PET as hypermetabolic spots and 36 lesions were only identified on CT 6

MRI-Gd: 133 lesions  In detecting individual brain Metastasis on FDG-PET/CT: Sensitivity and accuracy of 55% Specificity: /  no true negative lesions present

On scan basis: FDG-PET/CT : 22/49: + - MRI-Gd: 23/49 + in 18 cases : + on PET and CE CT 4 only on CE CT +  all cases confirmed by MRI - MRI-Gd: 23/49 + = PET-CT SCAN DEMONSTRATED THE PRESENCE OF BRAIN METASTASES IN 22 SCANS 8

In determining the existence of CNS involvement in MM on FDG-PET/CT: Sensitivity: 96% Accuracy: 98% Specificity: 100%

1hypometabolic meta in the left frontal cortex, periferic contrast captation and perilesional oedema 02/2009 2nd milimetric lesion right frontal on MRI CECT PET Koster (melanoma at the back, lung –and brain M+) T2 T1 -Gd T1+Gd

PT 1 04/2009 CECT PET/CT Increase in number and volume of M+. Largest M+ in the right frontal cortex (max.  4,5 cm) is now hypermetabolic with perilesional hypometabolism = increase in surrounding oedema. PT 1 04/2009 CECT PET/CT Koster T2 T1+Gd

PT 2 3 Known brainmetastases : in the right superior frontal, left frontal and right temporal cortex, all with surrounding oedema T1+Gd CECT PET Van eeckhout : hypermetabolic meta in right upper frontal cortex, 1 hypometabolic in the left frontal cortex and 1 hypermetabolic in the right temporal cortex. Perilesional oedema, most pronounced in the left frontal cortex. CECT PET T1+Gd

Conclusions Including the brain in the FOV for screening or FU of MM with FDG-PET/CT is usefull. FDG-PET/CT relatively low sensitivity for identifying all individual brainM+ (55%) with the use of CE CT and acquisition in venous phase FDG-PET/CT performs well in detecting the presence of brainM+ in known MM

Discussion  Advantage of including the brain in FDG-PET/CT: Potentially earlier detection of brainmetastases Faster and more efficient treatment Decreasing/preventing the related morbidity In case of negative FDG PET/CT and suspected clinical findings a CE MRI remains mandatory

Selection of paired PET/CT and MRIscans: SELECTION BIAS Overrepresentation of cases with brain metastases compared to whole melanoma population MRIscans were not performed for ALL the patients with known MM in our hospital: Routine baseline/ follow-up Suspicious clinical findings Therapeutic monitoring of cerebral M+