18FNa-fluoride has a higher extraction with respect to 99mTc

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Rev Esp Med Nucl Imagen Mol. 2014;33(1):52–53
Interesting image
18
FNa-fluoride has a higher extraction with respect to 99m Tc-methylene
diphosphonate: Mismatch in a case of meningioma
El 18 F-fluoruro sódico (18 FNa) muestra una mayor extracción que el
99m
Tc-metilen-difosfonato: discordancia en un meningioma
G.L. Cascini a , V. Cuccurullo b , L. Mansi b,∗
a
b
Department of Radiological Sciences, University of Catanzaro, Catanzaro, Italy
Department of Radiological Sciences, Second University of Naples, Naples, Italy
a r t i c l e
i n f o
Article history:
Received 21 January 2013
Accepted 2 April 2013
Available online 31 August 2013
A 47-year-old patient, operated for breast cancer and with a
previous negative bone scintigraphy, underwent a CT for lumbar
pain, which identified a L1 vertebral collapse, suspected for metastasis. A PET-CT with 18 FNa-fluoride (NaF) showed a faint uptake
at L1 level, interpreted as benign, and a focal and avid lesion in
the right parietal region, diagnosed as suspicious meningioma by
CT. A bone scan resulted negative, also at the level of the skull
lesion. The parietal lesion, monitored for one year, was surgically
removed and histologically confirmed as benign meningioma. Differences in pharmacokinetic and not only technical issues may
be the explanation for MDP/NaF mismatch in bone abnormalities,
being significantly higher the early radiotracer’s extraction of NaF
respect to 99m Tc-diphosphonates.1 This case supports the evidence
that the higher sensitivity of NaF with respect to MDP is dependent
not only on technical factors, but also on a higher extraction determining a possible higher uptake.2,3 Moreover, in the presence of
focal NaF uptake at level of the skull, CT is pivotal to differentiate
benign lesions from bone metastases (Figs. 1–3).
Fig. 1. PET-CT with 18 FNa-fluoride: a faint uptake at L1, interpreted as benign, was
seen together with an unexpected focal intense uptake in the right parietal region.
The skull lesion was clearly evident at MIP images (A) as well as at trans-axial plane
(B). At 90 min after i.v. administration SUV max was 9.2. The uptake corresponded
to an extra-axial calcified lesion of the right parietal lobe at co-registered CT planes
(C). The histology after kyphoplasty confirmed the absence of neoplasm at L1.
∗ Corresponding author.
E-mail address: luigi.mansi@unina2.it (L. Mansi).
2253-654X/$ – see front matter © 2013 Elsevier España, S.L. and SEMNIM. All rights reserved.
http://dx.doi.org/10.1016/j.remn.2013.04.004
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Fig. 2. Diagnostic CT with bone (A) and brain (B) window at level of the lesion identified by 18 FNa-fluoride PET-CT. The small calcified lesion appears rounded and elongated
with a broad attachment to the dura. Density was homogeneous in pre-contrast images (C) with a mild contrast enhancement in arterial phase (D). A meningioma with
benign features was suspected, confirmed by histology at surgery performed one year later.
Fig. 3. Bone scintigraphy 6 months after 18 FNa-fluoride PET-CT and before surgery. Whole body (A) acquisition demonstrated the absence of focal uptake in the skull. Only in
dynamic vascular phase in anterior view (B) a mild transitory and progressive uptake appeared in the right parietal region (arrow), in agreement with a vascularized lesion
showing a higher blood pool non accompanied by a significant deposition of MDP in the delayed osteoblastic phase, because of a low extraction. The corresponding axial
planes on 18 FNa-fluoride PET (C) and 99m Tc-MDP-SPECT (D).
Conflict of interest
The authors have no conflicts of interest to declare.
References
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