Jean Yves Devaux

Psychogenic parkinsonism: A combination of clinical, electrophysiological, and [123I]-FP-CIT SPECT scan explorations improves diagnostic accuracy

We evaluated the concordance between independent clinical, electrophysiological, and [123I]‐FP‐CIT SPECT scan explorations as a staged procedure for an accurate diagnosis in 9 patients referred with a diagnosis of suspected psychogenic parkinsonism. Three patients were reclassified as pure psychogenic parkinsonism (PP), 6 with a form of combined psychogenic parkinsonism and Parkinsons disease (PP + PD), and none with pure Parkinsons disease (PD). Electrophysiological recordings showed the characteristics of psychogenic tremor in 5 of 7 patients with tremor. In two of these 5, PD tremor was also recorded. SPECT scan results were abnormal in five of 9 patients. In one case of clinically suspected PP + PD, SPECT scan results were normal. Long‐term follow‐up supported the final diagnosis of PP (initial clinical misdiagnosis). Electrophysiology contributes to the clinical diagnosis of psychogenic tremor and may help confirm associated organic PD tremor. [123I]‐FP‐CIT SPECT is a robust test to ascertain dopaminergic denervation and increase the confidence of the clinical and electrophysiological diagnosis of associated PD. A combination of clinical, electrophysiological, and [123I]‐FP‐CIT SPECT scan explorations improves diagnostic accuracy in order to distinguish PP from PP + PD.

Bone metastases of differentiated thyroid cancer: impact of early 131I-based detection on outcome

Bone is the second most frequent target of distant metastases in patients with differentiated thyroid cancer, and such forms carry a very poor prognosis. The impact of (131)I therapy in this setting is controversial. We describe the diagnostic circumstances and outcome of patients with bone metastases recently managed in two institutions. Among 921 consecutive thyroid cancer patients who had total thyroidectomy and (131)I ablation between January 2000 and December 2004 and who were subsequently monitored, bone metastases had been diagnosed in 16 patients. In three cases, the bone metastases were non-functioning (negative (131)I uptake) . These patients were treated with surgery and radiotherapy but progressed rapidly. The other 13 patients had functioning (positive (131)I uptake) bone metastases. In five of them, thyroid cancer was revealed by signs of distant involvement (bone pain, n = 4; dyspnea, n = 1). The bone metastases progressed in these five patients, despite local therapy and multiple courses of (131)I. The bone metastases in the remaining eight patients were discovered on the post-surgery (131)I therapy scan. Complementary radiological studies were negative except in one patient in whom one of the metastases (a 5 mm lesion of the right humerus) was visible on magnetic resonance imaging (MRI). Six of these patients showed a good response to (131)I therapy, with (131)I uptake and Tg levels becoming undetectable or showing a sharp fall. One patient refused (131)I therapy; bone metastases became visible on MRI within 1 year and the Tg level rose tenfold. The disease progressed in one patient despite (131)I therapy. Post-surgical (131)I ablation can contribute to early detection of bone metastases at a time when the Tg level may be only moderately elevated, when other radiological studies are negative, and when the disease is potentially curable by (131)I therapy.

[123I]-FP-CIT and [99mTc]-HMPAO single photon emission computed tomography in a new sporadic case of rapid-onset dystonia–parkinsonism

UNLABELLED Rapid-onset dystonia-parkinsonism (RDP) is a rare, autosomal-dominantly inherited syndrome characterized by abrupt onset, over hours to days, of dystonic and parkinsonian symptoms. To date, RDP has been described in a small number of families, and in only four sporadic cases. METHODS We here report a new sporadic case of RDP who has a novel de novo mutation in the ATP1A3 gene. Striatal dopamine transporters have been assessed quantitatively using [123I]-FP-CIT SPECT. A volume of interest (VOI) was drawn within the occipital cortex to obtain non-specific activity and specific to non-specific binding ratios (BR) were calculated. A single template of predefined VOI 3D-drawn on right and left caudate nucleus and putamen was applied to the spatially normalized BR images. BR values were compared to those obtained from an age-matched control group and from a group of patients suffering from Parkinsons disease (Hoehn and Yahr score 2 or 3). A [99mTc]-HMPAO cerebral blood flow study was also performed. RESULTS In the control group, BR values (mean+/-Standard Deviation) were 3.5+/-0.4 for the left striatum and 3.3+/-0.3 for the right one. RDP patients values were 3 and 2.7, respectively. In the Parkinson group, values were 1.6+/-0.3 and 1.7+/-0.4, respectively. [99mTc]-HMPAO scan showed homogeneous cortical and sub-cortical perfusion. CONCLUSION Quantification of striatal [123I]-FP-CIT uptake in a new sporadic case of RDP with a novel mutation in the ATP1A3 gene showed values just within the range of normality. [99mTc]-HMPAO scan was normal.

Estimation of the β+ Dose to the Embryo Resulting from 18F-FDG Administration During Early Pregnancy

Although 18F-FDG examinations are widely used, data are lacking on the dose to human embryo tissues in cases of exposure in early pregnancy. Although the photon component can easily be estimated from available data on the pharmacokinetics of 18F-FDG in female organs and from phantom measurements (considering the uterus as the target organ), the intensity of embryo tissue uptake, which is essential for deriving the β+ dose, is not known. We report the case of a patient who underwent 18F-FDG PET/CT for tumor surveillance and who was later found to have been pregnant at the time of the examination (embryo age, 8 wk). Methods: The patient received 320 MBq of 18F-FDG. Imaging started with an unenhanced CT scan 1 h after the injection, followed by PET acquisition. PET images were used to compute the total number of β+ emissions in embryo tissues per unit of injected activity, from standardized uptake value (SUV) measurements corrected for partial-volume effects. A Monte Carlo track structure code was then used to derive the β+ self-dose and the β+ cross-dose from amniotic fluid. The photon and CT doses were added to obtain the final dose received by the embryo. Results: The mean SUV in embryo tissues was 2.7, after correction for the partial-volume effect. The mean corrected SUV of amniotic fluid was 1.1. Monte Carlo simulation showed that the β+ dose to the embryo (self-dose plus cross-dose from amniotic fluid) was 1.8E−2 mGy per MBq of injected 18F-FDG. Based on MIRD data for the photon dose to the uterus, the estimated photon dose to the embryo was 1.5E−2 mGy/MBq. Thus, the specific 18F-FDG dose to the embryo was 3.3E−2 mGy/MBq (10.6 mGy in this patient). The CT scan added a further 8.3 mGy. Conclusion: The dose to the embryo is 3.3E−2 mGy/MBq of 18F-FDG. The β+ dose contributes 55% of the total dose. This value is higher than previous estimates in late nonhuman-primate pregnancies.

Increased serum thyroglobulin levels and negative imaging in thyroid cancer patients: are there sources of benign secretion? A speculative short review.

After thyroidectomy and 131I ablation for differentiated thyroid cancer (DTC), serum thyroglobulin (Tg) became a sensitive marker of residual disease. It is not uncommon to find patients at follow-up with persistent serum Tg levels and no other clinical or imaging evidence for the disease. The vast majority of these patients, most probably, have occult foci of disease, often in minute cervical lymph nodes. A review of the literature including papers published on PubMed/Medline until June 2010 was made. In this study we speculated that a minority of patients who had undergone surgery for differentiated thyroid cancer might have benign sources of Tg secretion at follow-up. These sources may be foci of radio-resistant ectopic thyroid tissue or a thyroid stimulating hormone-stimulated thymus.

In vivo quantification of 18f-fdg uptake in human placenta during early pregnancy.

18F-FDG is the most widely used PET radiopharmaceutical. Nevertheless, no data for 18F-FDG uptake in the human placenta have been reported. We recently reported on embryo dosimetry in a woman who underwent an 18F-FDG PET/CT scan during early pregnancy. In the present work we attempt an in vivo quantification of the 18F-FDG uptake by the placenta. The 27-y-old woman received 320 MBq of 18F-FDG for a follow-up study for Hodgkin’s lymphoma and was later discovered to be pregnant (embryo age = 8 wk). Imaging started 1 h after injection. The maximum placental tissue uptake (SUVmax) was 2.5. This value was conservatively attributed to the entire placental volume, i.e., 45 mL, a value representative of the average dimensions of a normal placenta at 8 wk. On the basis of these measurements, placenta 18F-FDG uptake in our patient was 0.19% of the injected activity. A Monte Carlo simulation was used to derive the photon dose to the embryo from the placenta (0.022 × 10−2 mGy per MBq of injected 18F-FDG) and from the surrounding amniotic fluid (0.017 × 10−2 mGy MBq−1). This increases our previously calculated dose (3.3 × 10−2 mGy MBq−1) by only a small fraction (1.18%), which does not justify modifying the previous estimate given the overall uncertainties.

Should 'low-risk' thyroid cancer patients with residual thyroglobulin be re-treated with iodine 131?

Objective  The American consensus statement on patients with low‐risk thyroid cancer, published in 2003, suggests repeat 131I therapy if the thyroglobulin value is elevated at first follow‐up. We evaluated this strategy in our practice.

Scintigraphic visualization of glossal thyroid tissue during the follow-up of thyroid cancer patients.

Purpose: Nests of thyroid tissue in the tongue are described in about 10% of necropsies. This ectopic thyroid tissue usually lies dormant, but may manifest itself during times of increased stimulation. The aim of our study was to assess the frequency of lingual thyroid visualization on I-131 diagnostic whole-body scan during the follow-up of thyroid cancer patients. Material and Methods: We reviewed the files of 548 consecutive patients who underwent a diagnostic whole-body scan with 200 MBq of I-131 between January 2000 and December 2005, as part of the follow-up for a differentiated thyroid cancer. Every patient had been previously treated with a total thyroidectomy and had received 3.7 GBq (100 mCi) of I-131 for remnant ablation. Results: A focus of uptake located between the 2 submandibular salivary glands, suggestive of ectopic thyroid tissue in the tongue or in the upper part of the thyroglossal duct, was found in 5 of the 548 patients (0.9%). In only one of these patients was the uptake visible at the time of postsurgery thyroid remnant ablation scan. Thyroglobulin (Tg) levels were positive under stimulation in 3 of the 5 patients, and another patient had undetectable Tg, but positive anti-Tg antibodies. Radiologic imaging (MRI and/or ultrasound) was performed in 3 patients and confirmed the presence of a mass suggestive of ectopic thyroid tissue in two. Invasive lingual biopsy was not performed to verify the benign nature. Conclusion: When examining whole-body scans (therapeutic or diagnostic) in a patient with persistent Tg detection after thyroid ablation, one should carefully search for any uptake between the submandibular glands that may be suggestive of ectopic tissue.

18F-FDG PET/CT visualisation of tumor seeding after percutaneous radiofrequency ablation of metastases

Percutaneous radiofrequency ablation (PRFTA) of intrahepatic tumours is a minimally invasive procedure. It may, however, result in needle-track tumor seeding. Here we present the case of a metastatic lesion of the thoracoabdominal wall after PRFTA of a liver metastasis, discovered by F-FDG PET/CT. The patient was a 59year-old man who had had PRFTA for a liver metastasis of colonic cancer 6 months previously and was referred for F-FDG PET/CTevaluation of the treatment response. No residual hypermetabolism was seen in the treated metastasis, but transaxial PET/CT images clearly showed a metastatic lesion in the percutaneous access track. The lesion was treated by surgical resection and radiotherapy. Tumour seeding after PRFTA, first reported by Llovet [1], is a rare complication, occurring after between 0% and 2.8% of procedures [2–6]. Several mechanisms may contribute to tumour seeding after PRFTA. For example, viable tumour cells may adhere to the needle during its retraction, or may be forced into the track with a little blood or by sudden intratumoural hyperpressure [7]. The lesion we describe was missed on a CT scan performed a few days previously, probably because the thoraco-abdominal wall is sometimes overlookedwhen interpreting CTscans. F-FDG PET (a) clearly identified the needle track metastasis, and its combination with CT (b, c) provided precise topographic localisation of the lesion and ruled out bone and liver metastasis. References

La TEP dans le cancer de la glande thyroïde

Points essentiels La TEP au FDG peut permettre de deceler un cancer de la thyroide chez des patients adresses pour l’exploration d’un autre cancer. En revanche, elle n’est pas indiquee, faute d’une specificite suffisante, pour caracteriser un nodule thyroidien : l’echographie et la cytoponction permettent le diagnostic histologique, et peuvent etre completees par la scintigraphie a l’iode-123 en cas de suspicion de nodule autonome. Il n’existe pas d’etude rapportant l’interet de la TEP lors de la stadification peoperatoire. Dans le suivi du patient thyroidectomise pour adenocarcinome thyroidien, la TEP au FDG est utile pour localiser la recidive en cas d’augmentation de la thyroglobulinemie alors qu’aucun foyer fixant l’iode-131 n’est retrouve ; un geste chirurgical peut parfois etre indique. Cependant, la TEP au FDG meriterait a notre avis d’etre utilisee bien plus largement et bien plus tot dans l’evolution : il a ete montre que la fixation initiale du FDG avait une valeur pronostique sur la survie et que la plupart des lesions cancereuses fixaient soit l’iode-131 soit le FDG. Dans le suivi du cancer medullaire de la thyroide, la TEP au FDG est superieure a toutes les scintigraphies pour deceler le tissu residuel, en particulier dans les formes evolutives ou la concentration plasmatique d’antigene carcinoembryonnaire (ACE) augmente rapidement. La TEP a la FDopa semble de meilleure sensibilite, et merite d’etre utilisee en cas de recidive occulte ; trois exemples sont fournis.