Utility of positron emission tomography for tumour surveillance in children with neurofibromatosis type 1.
OBJECTIVE
There is little consensus regarding optimal surveillance of optic pathway glioma (OPG) and plexiform neurofibroma (PNF) in childhood neurofibromatosis type 1 (NF1). (18)F-2-Fluoro-2-deoxy-D: -glucose (FDG) positron emission tomography and computed tomography (PET/CT) is employed in the surveillance of adult PNFs; but its utility has neither been specifically studied in children with PNFs nor in children with OPG.


METHODS
Review of PET/CT studies was performed in NF1 children with OPG or PNF. FDG-avidity of tumours was semi-quantitatively analysed and graded by calculating the maximum standardised uptake value (SUV(max)) [grade 1: <3 (low), grade 2: >3-<4 (intermediate), grade 3: >4 (intense)].


RESULTS
Eighteen children (ten girls; median age: 8.5-years) had PET/CT. Nineteen OPGs were imaged. The SUV(max) could be measured in 16. Ten were grade 1 and three each were grade 2 and grade 3. FDG-avidity reduced from grade 3 to grade 1 in two symptomatic OPGs following chemotherapy and this was associated with clinical improvement. PET/CT diagnosed symptomatic OPGs with a sensitivity of 0.625 [95% confidence interval (CI): 0.259-0.897] and specificity of 0.875 (95% CI: 0.466-0.993). Sixteen PNFs were imaged. Twelve were grade 1 and two each were grade 2 and grade 3. The two grade 3 PNFs were confirmed malignant peripheral nerve sheath tumours. PET/CT diagnosed malignant transformation with a sensitivity of 1.0 (95% CI: 0.197-1.0) and specificity of 0.857 (95% CI: 0.561-0.974).


CONCLUSIONS
PET/CT may contribute useful information to the surveillance of OPG in childhood NF1-particularly to identify progressive, symptomatic tumours. As in adults, PET/CT is useful for the detection of malignant transformation in PNFs in children with NF1.
Moharir
Mahendranath
M
Division of Neurology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada. mahendranath.moharir@sickkids.ca
London
Kevin
K
Howman-Giles
Robert
R
North
Kathryn
K
D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D018318:Neurofibroma, Plexiform / Q000000981:diagnostic imaging; D009456:Neurofibromatosis 1 / Q000000981:diagnostic imaging*; D020339:Optic Nerve Glioma / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
D019788:Fluorodeoxyglucose F18