Radio-guided surgery for lymph node recurrences of differentiated thyroid cancer.

The objectives of this study were to assess the reliability of radio-iodine (131I) and a gamma probe for radio-guided surgery (RGS) to detect and then radically dissect lymph node recurrences (LNRs) in 10 patients with differentiated thyroid cancer (DTC). The major inclusion criterion was the presence of an iodine-positive LNR after previous total thyroidectomy and at least two ineffective 131I treatments. The protocol was designed as follows. Day 0: all patients were hospitalized and received 3.7 GBq of 131I in the hypothyroid condition. Day 3: presurgery whole-body scan with a therapeutic dose (TxWBS). Day 5: neck surgery using a gamma probe (Navigator GPS, AutoSuture, Italy), recording the absolute counts and the lesion/background (L/B) counts ratio. Day 7: post-surgery TxWBS performed using the remaining radioactivity. The presurgery TxWBS was positive in all patients, and the post-surgery TxWBS showed a negative pattern in 7 of 10 patients, suggesting the efficacy of the surgical procedure in most of the patients. After RGS the mean decrease in the absolute counts and the L/B counts ratio were 77.6% (52.7% minimum, 94.6% maximum) and 77.4% (52.3% minimum, 94.8% maximum), respectively. After operation the surgeon judged the procedure to be decisive in two patients, favorable in six, and irrelevant in two. The final histologic examination showed the presence of 78 lymph node metastases (mean of 8 per patient). There were 33 neoplastic lesions found by both TxWBS and gamma probe evaluations; 41 were shown only by gamma probe, and 4 were negative by both TxWBS and gamma probe evaluations. This protocol permitted us to look for neoplastic foci with high sensitivity and specificity, and we were able to remove lymph node metastases resistant to radioiodine therapy at a single session. The protocol also allowed detection of some additional tumoral foci in sclerotic areas or behind vascular structures that are difficult to identify and were not seen at the presurgery TxWBS evaluation. However, because of the possible false-negative results, complete excision must be undertaken in high risk patients with a local recurrence to eradicate the largest number of lymph nodes, independent of the counts measured by the gamma probe.

Ictal brain SPET during seizures pharmacologically provoked with pentylenetetrazol: a new diagnostic procedure in drug-resistant epileptic patients.

Functional brain imaging plays an important role in seizure focus localisation. However, truly ictal single-photon emission tomography (SPET) studies are not routinely performed owing to technical problems associated with the use of tracers and methodological and logistical difficulties. In this study we tried to resolve both of these issues by means of a new procedure: technetium-99m ethyl cysteinate dimer (ECD) brain SPET performed during seizures pharmacologically provoked with pentylenetetrazol, a well-known central and respiratory stimulant. We studied 33 drug-resistant epileptic patients. All patients underwent anamnestic evaluation, neuropsychological and psychodynamic assessment, magnetic resonance imaging, interictal and ictal video-EEG monitoring, and interictal and ictal SPET with (99m)Tc-ECD. In order to obtain truly ictal SPET, 65 mg of pentylenetetrazol was injected every 2 minutes and, immediately the seizure began, 740 MBq of (99m)Tc-ECD was injected. The scintigraphic findings were considered abnormal if a single area of hyperperfusion was present and corresponded to the site of a single area of hypoperfusion at interictal SPET: the "hypo-hyperperfusion" SPET pattern. In 27 of the 33 patients (82%), interictal-ictal SPET showed the hypo-hyperperfusion SPET pattern. Video-EEG showed a single epileptogenic zone in 21/33 patients (64%), and MRI showed anatomical lesions in 19/33 patients (57%). Twenty-two of the 27 patients with hypo-hyperperfusion SPET pattern underwent ablative or palliative surgery and were seizure-free at 3 years of follow-up. No adverse effects were noted during pharmacologically provoked seizure. It is concluded that ictal brain SPET performed during pharmacologically provoked seizure provides truly ictal images because (99m)Tc-ECD is injected immediately upon seizure onset. Using this feasible procedure it is possible to localise the focus, to avoid the limitations due to the unpredictability of seizures, to avoid pitfalls due to late injection, to avoid intracranial EEG recording and to minimise costs. The clinical value of our method is confirmed by the good outcome after 3 years of follow-up in those patients submitted to ablative or palliative surgery.